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linux-next/net/bluetooth/smp.c

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/*
BlueZ - Bluetooth protocol stack for Linux
Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License version 2 as
published by the Free Software Foundation;
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.
IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) AND AUTHOR(S) BE LIABLE FOR ANY
CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
ALL LIABILITY, INCLUDING LIABILITY FOR INFRINGEMENT OF ANY PATENTS,
COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS, RELATING TO USE OF THIS
SOFTWARE IS DISCLAIMED.
*/
#include <linux/crypto.h>
#include <linux/scatterlist.h>
#include <crypto/b128ops.h>
#include <net/bluetooth/bluetooth.h>
#include <net/bluetooth/hci_core.h>
#include <net/bluetooth/l2cap.h>
#include <net/bluetooth/mgmt.h>
#include "ecc.h"
#include "smp.h"
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
#define SMP_ALLOW_CMD(smp, code) set_bit(code, &smp->allow_cmd)
/* Keys which are not distributed with Secure Connections */
#define SMP_SC_NO_DIST (SMP_DIST_ENC_KEY | SMP_DIST_LINK_KEY);
#define SMP_TIMEOUT msecs_to_jiffies(30000)
#define AUTH_REQ_MASK(dev) (test_bit(HCI_SC_ENABLED, &(dev)->dev_flags) ? \
0x1f : 0x07)
#define KEY_DIST_MASK 0x07
/* Maximum message length that can be passed to aes_cmac */
#define CMAC_MSG_MAX 80
enum {
SMP_FLAG_TK_VALID,
SMP_FLAG_CFM_PENDING,
SMP_FLAG_MITM_AUTH,
SMP_FLAG_COMPLETE,
SMP_FLAG_INITIATOR,
SMP_FLAG_SC,
SMP_FLAG_REMOTE_PK,
SMP_FLAG_DEBUG_KEY,
SMP_FLAG_WAIT_USER,
SMP_FLAG_DHKEY_PENDING,
};
struct smp_chan {
struct l2cap_conn *conn;
struct delayed_work security_timer;
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
unsigned long allow_cmd; /* Bitmask of allowed commands */
u8 preq[7]; /* SMP Pairing Request */
u8 prsp[7]; /* SMP Pairing Response */
u8 prnd[16]; /* SMP Pairing Random (local) */
u8 rrnd[16]; /* SMP Pairing Random (remote) */
u8 pcnf[16]; /* SMP Pairing Confirm */
u8 tk[16]; /* SMP Temporary Key */
u8 enc_key_size;
u8 remote_key_dist;
bdaddr_t id_addr;
u8 id_addr_type;
u8 irk[16];
struct smp_csrk *csrk;
struct smp_csrk *slave_csrk;
struct smp_ltk *ltk;
struct smp_ltk *slave_ltk;
struct smp_irk *remote_irk;
u8 *link_key;
unsigned long flags;
u8 method;
u8 passkey_round;
/* Secure Connections variables */
u8 local_pk[64];
u8 local_sk[32];
u8 remote_pk[64];
u8 dhkey[32];
u8 mackey[16];
struct crypto_blkcipher *tfm_aes;
struct crypto_hash *tfm_cmac;
};
/* These debug key values are defined in the SMP section of the core
* specification. debug_pk is the public debug key and debug_sk the
* private debug key.
*/
static const u8 debug_pk[64] = {
0xe6, 0x9d, 0x35, 0x0e, 0x48, 0x01, 0x03, 0xcc,
0xdb, 0xfd, 0xf4, 0xac, 0x11, 0x91, 0xf4, 0xef,
0xb9, 0xa5, 0xf9, 0xe9, 0xa7, 0x83, 0x2c, 0x5e,
0x2c, 0xbe, 0x97, 0xf2, 0xd2, 0x03, 0xb0, 0x20,
0x8b, 0xd2, 0x89, 0x15, 0xd0, 0x8e, 0x1c, 0x74,
0x24, 0x30, 0xed, 0x8f, 0xc2, 0x45, 0x63, 0x76,
0x5c, 0x15, 0x52, 0x5a, 0xbf, 0x9a, 0x32, 0x63,
0x6d, 0xeb, 0x2a, 0x65, 0x49, 0x9c, 0x80, 0xdc,
};
static const u8 debug_sk[32] = {
0xbd, 0x1a, 0x3c, 0xcd, 0xa6, 0xb8, 0x99, 0x58,
0x99, 0xb7, 0x40, 0xeb, 0x7b, 0x60, 0xff, 0x4a,
0x50, 0x3f, 0x10, 0xd2, 0xe3, 0xb3, 0xc9, 0x74,
0x38, 0x5f, 0xc5, 0xa3, 0xd4, 0xf6, 0x49, 0x3f,
};
static inline void swap_buf(const u8 *src, u8 *dst, size_t len)
{
size_t i;
for (i = 0; i < len; i++)
dst[len - 1 - i] = src[i];
}
static int aes_cmac(struct crypto_hash *tfm, const u8 k[16], const u8 *m,
size_t len, u8 mac[16])
{
uint8_t tmp[16], mac_msb[16], msg_msb[CMAC_MSG_MAX];
struct hash_desc desc;
struct scatterlist sg;
int err;
if (len > CMAC_MSG_MAX)
return -EFBIG;
if (!tfm) {
BT_ERR("tfm %p", tfm);
return -EINVAL;
}
desc.tfm = tfm;
desc.flags = 0;
crypto_hash_init(&desc);
/* Swap key and message from LSB to MSB */
swap_buf(k, tmp, 16);
swap_buf(m, msg_msb, len);
BT_DBG("msg (len %zu) %*phN", len, (int) len, m);
BT_DBG("key %16phN", k);
err = crypto_hash_setkey(tfm, tmp, 16);
if (err) {
BT_ERR("cipher setkey failed: %d", err);
return err;
}
sg_init_one(&sg, msg_msb, len);
err = crypto_hash_update(&desc, &sg, len);
if (err) {
BT_ERR("Hash update error %d", err);
return err;
}
err = crypto_hash_final(&desc, mac_msb);
if (err) {
BT_ERR("Hash final error %d", err);
return err;
}
swap_buf(mac_msb, mac, 16);
BT_DBG("mac %16phN", mac);
return 0;
}
static int smp_f4(struct crypto_hash *tfm_cmac, const u8 u[32], const u8 v[32],
const u8 x[16], u8 z, u8 res[16])
{
u8 m[65];
int err;
BT_DBG("u %32phN", u);
BT_DBG("v %32phN", v);
BT_DBG("x %16phN z %02x", x, z);
m[0] = z;
memcpy(m + 1, v, 32);
memcpy(m + 33, u, 32);
err = aes_cmac(tfm_cmac, x, m, sizeof(m), res);
if (err)
return err;
BT_DBG("res %16phN", res);
return err;
}
static int smp_f5(struct crypto_hash *tfm_cmac, u8 w[32], u8 n1[16], u8 n2[16],
u8 a1[7], u8 a2[7], u8 mackey[16], u8 ltk[16])
{
/* The btle, salt and length "magic" values are as defined in
* the SMP section of the Bluetooth core specification. In ASCII
* the btle value ends up being 'btle'. The salt is just a
* random number whereas length is the value 256 in little
* endian format.
*/
const u8 btle[4] = { 0x65, 0x6c, 0x74, 0x62 };
const u8 salt[16] = { 0xbe, 0x83, 0x60, 0x5a, 0xdb, 0x0b, 0x37, 0x60,
0x38, 0xa5, 0xf5, 0xaa, 0x91, 0x83, 0x88, 0x6c };
const u8 length[2] = { 0x00, 0x01 };
u8 m[53], t[16];
int err;
BT_DBG("w %32phN", w);
BT_DBG("n1 %16phN n2 %16phN", n1, n2);
BT_DBG("a1 %7phN a2 %7phN", a1, a2);
err = aes_cmac(tfm_cmac, salt, w, 32, t);
if (err)
return err;
BT_DBG("t %16phN", t);
memcpy(m, length, 2);
memcpy(m + 2, a2, 7);
memcpy(m + 9, a1, 7);
memcpy(m + 16, n2, 16);
memcpy(m + 32, n1, 16);
memcpy(m + 48, btle, 4);
m[52] = 0; /* Counter */
err = aes_cmac(tfm_cmac, t, m, sizeof(m), mackey);
if (err)
return err;
BT_DBG("mackey %16phN", mackey);
m[52] = 1; /* Counter */
err = aes_cmac(tfm_cmac, t, m, sizeof(m), ltk);
if (err)
return err;
BT_DBG("ltk %16phN", ltk);
return 0;
}
static int smp_f6(struct crypto_hash *tfm_cmac, const u8 w[16],
const u8 n1[16], u8 n2[16], const u8 r[16],
const u8 io_cap[3], const u8 a1[7], const u8 a2[7],
u8 res[16])
{
u8 m[65];
int err;
BT_DBG("w %16phN", w);
BT_DBG("n1 %16phN n2 %16phN", n1, n2);
BT_DBG("r %16phN io_cap %3phN a1 %7phN a2 %7phN", r, io_cap, a1, a2);
memcpy(m, a2, 7);
memcpy(m + 7, a1, 7);
memcpy(m + 14, io_cap, 3);
memcpy(m + 17, r, 16);
memcpy(m + 33, n2, 16);
memcpy(m + 49, n1, 16);
err = aes_cmac(tfm_cmac, w, m, sizeof(m), res);
if (err)
return err;
BT_DBG("res %16phN", res);
return err;
}
static int smp_g2(struct crypto_hash *tfm_cmac, const u8 u[32], const u8 v[32],
const u8 x[16], const u8 y[16], u32 *val)
{
u8 m[80], tmp[16];
int err;
BT_DBG("u %32phN", u);
BT_DBG("v %32phN", v);
BT_DBG("x %16phN y %16phN", x, y);
memcpy(m, y, 16);
memcpy(m + 16, v, 32);
memcpy(m + 48, u, 32);
err = aes_cmac(tfm_cmac, x, m, sizeof(m), tmp);
if (err)
return err;
*val = get_unaligned_le32(tmp);
*val %= 1000000;
BT_DBG("val %06u", *val);
return 0;
}
static int smp_e(struct crypto_blkcipher *tfm, const u8 *k, u8 *r)
{
struct blkcipher_desc desc;
struct scatterlist sg;
uint8_t tmp[16], data[16];
int err;
if (tfm == NULL) {
BT_ERR("tfm %p", tfm);
return -EINVAL;
}
desc.tfm = tfm;
desc.flags = 0;
/* The most significant octet of key corresponds to k[0] */
swap_buf(k, tmp, 16);
err = crypto_blkcipher_setkey(tfm, tmp, 16);
if (err) {
BT_ERR("cipher setkey failed: %d", err);
return err;
}
/* Most significant octet of plaintextData corresponds to data[0] */
swap_buf(r, data, 16);
sg_init_one(&sg, data, 16);
err = crypto_blkcipher_encrypt(&desc, &sg, &sg, 16);
if (err)
BT_ERR("Encrypt data error %d", err);
/* Most significant octet of encryptedData corresponds to data[0] */
swap_buf(data, r, 16);
return err;
}
static int smp_h6(struct crypto_hash *tfm_cmac, const u8 w[16],
const u8 key_id[4], u8 res[16])
{
int err;
BT_DBG("w %16phN key_id %4phN", w, key_id);
err = aes_cmac(tfm_cmac, w, key_id, 4, res);
if (err)
return err;
BT_DBG("res %16phN", res);
return err;
}
static int smp_ah(struct crypto_blkcipher *tfm, u8 irk[16], u8 r[3], u8 res[3])
{
u8 _res[16];
int err;
/* r' = padding || r */
memcpy(_res, r, 3);
memset(_res + 3, 0, 13);
err = smp_e(tfm, irk, _res);
if (err) {
BT_ERR("Encrypt error");
return err;
}
/* The output of the random address function ah is:
* ah(h, r) = e(k, r') mod 2^24
* The output of the security function e is then truncated to 24 bits
* by taking the least significant 24 bits of the output of e as the
* result of ah.
*/
memcpy(res, _res, 3);
return 0;
}
bool smp_irk_matches(struct hci_dev *hdev, u8 irk[16], bdaddr_t *bdaddr)
{
struct l2cap_chan *chan = hdev->smp_data;
struct crypto_blkcipher *tfm;
u8 hash[3];
int err;
if (!chan || !chan->data)
return false;
tfm = chan->data;
BT_DBG("RPA %pMR IRK %*phN", bdaddr, 16, irk);
err = smp_ah(tfm, irk, &bdaddr->b[3], hash);
if (err)
return false;
return !memcmp(bdaddr->b, hash, 3);
}
int smp_generate_rpa(struct hci_dev *hdev, u8 irk[16], bdaddr_t *rpa)
{
struct l2cap_chan *chan = hdev->smp_data;
struct crypto_blkcipher *tfm;
int err;
if (!chan || !chan->data)
return -EOPNOTSUPP;
tfm = chan->data;
get_random_bytes(&rpa->b[3], 3);
rpa->b[5] &= 0x3f; /* Clear two most significant bits */
rpa->b[5] |= 0x40; /* Set second most significant bit */
err = smp_ah(tfm, irk, &rpa->b[3], rpa->b);
if (err < 0)
return err;
BT_DBG("RPA %pMR", rpa);
return 0;
}
static int smp_c1(struct crypto_blkcipher *tfm_aes, u8 k[16], u8 r[16],
u8 preq[7], u8 pres[7], u8 _iat, bdaddr_t *ia, u8 _rat,
bdaddr_t *ra, u8 res[16])
{
u8 p1[16], p2[16];
int err;
memset(p1, 0, 16);
/* p1 = pres || preq || _rat || _iat */
p1[0] = _iat;
p1[1] = _rat;
memcpy(p1 + 2, preq, 7);
memcpy(p1 + 9, pres, 7);
/* p2 = padding || ia || ra */
memcpy(p2, ra, 6);
memcpy(p2 + 6, ia, 6);
memset(p2 + 12, 0, 4);
/* res = r XOR p1 */
u128_xor((u128 *) res, (u128 *) r, (u128 *) p1);
/* res = e(k, res) */
err = smp_e(tfm_aes, k, res);
if (err) {
BT_ERR("Encrypt data error");
return err;
}
/* res = res XOR p2 */
u128_xor((u128 *) res, (u128 *) res, (u128 *) p2);
/* res = e(k, res) */
err = smp_e(tfm_aes, k, res);
if (err)
BT_ERR("Encrypt data error");
return err;
}
static int smp_s1(struct crypto_blkcipher *tfm_aes, u8 k[16], u8 r1[16],
u8 r2[16], u8 _r[16])
{
int err;
/* Just least significant octets from r1 and r2 are considered */
memcpy(_r, r2, 8);
memcpy(_r + 8, r1, 8);
err = smp_e(tfm_aes, k, _r);
if (err)
BT_ERR("Encrypt data error");
return err;
}
static void smp_send_cmd(struct l2cap_conn *conn, u8 code, u16 len, void *data)
{
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp;
struct kvec iv[2];
struct msghdr msg;
if (!chan)
return;
BT_DBG("code 0x%2.2x", code);
iv[0].iov_base = &code;
iv[0].iov_len = 1;
iv[1].iov_base = data;
iv[1].iov_len = len;
memset(&msg, 0, sizeof(msg));
msg.msg_iov = (struct iovec *) &iv;
msg.msg_iovlen = 2;
l2cap_chan_send(chan, &msg, 1 + len);
if (!chan->data)
return;
smp = chan->data;
cancel_delayed_work_sync(&smp->security_timer);
schedule_delayed_work(&smp->security_timer, SMP_TIMEOUT);
}
static u8 authreq_to_seclevel(u8 authreq)
{
if (authreq & SMP_AUTH_MITM) {
if (authreq & SMP_AUTH_SC)
return BT_SECURITY_FIPS;
else
return BT_SECURITY_HIGH;
} else {
return BT_SECURITY_MEDIUM;
}
}
static __u8 seclevel_to_authreq(__u8 sec_level)
{
switch (sec_level) {
case BT_SECURITY_FIPS:
case BT_SECURITY_HIGH:
return SMP_AUTH_MITM | SMP_AUTH_BONDING;
case BT_SECURITY_MEDIUM:
return SMP_AUTH_BONDING;
default:
return SMP_AUTH_NONE;
}
}
static void build_pairing_cmd(struct l2cap_conn *conn,
struct smp_cmd_pairing *req,
struct smp_cmd_pairing *rsp, __u8 authreq)
{
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp = chan->data;
struct hci_conn *hcon = conn->hcon;
struct hci_dev *hdev = hcon->hdev;
u8 local_dist = 0, remote_dist = 0;
if (test_bit(HCI_BONDABLE, &conn->hcon->hdev->dev_flags)) {
local_dist = SMP_DIST_ENC_KEY | SMP_DIST_SIGN;
remote_dist = SMP_DIST_ENC_KEY | SMP_DIST_SIGN;
authreq |= SMP_AUTH_BONDING;
} else {
authreq &= ~SMP_AUTH_BONDING;
}
if (test_bit(HCI_RPA_RESOLVING, &hdev->dev_flags))
remote_dist |= SMP_DIST_ID_KEY;
if (test_bit(HCI_PRIVACY, &hdev->dev_flags))
local_dist |= SMP_DIST_ID_KEY;
if (test_bit(HCI_SC_ENABLED, &hdev->dev_flags)) {
if ((authreq & SMP_AUTH_SC) &&
test_bit(HCI_SSP_ENABLED, &hdev->dev_flags)) {
local_dist |= SMP_DIST_LINK_KEY;
remote_dist |= SMP_DIST_LINK_KEY;
}
} else {
authreq &= ~SMP_AUTH_SC;
}
if (rsp == NULL) {
req->io_capability = conn->hcon->io_capability;
req->oob_flag = SMP_OOB_NOT_PRESENT;
req->max_key_size = SMP_MAX_ENC_KEY_SIZE;
req->init_key_dist = local_dist;
req->resp_key_dist = remote_dist;
req->auth_req = (authreq & AUTH_REQ_MASK(hdev));
smp->remote_key_dist = remote_dist;
return;
}
rsp->io_capability = conn->hcon->io_capability;
rsp->oob_flag = SMP_OOB_NOT_PRESENT;
rsp->max_key_size = SMP_MAX_ENC_KEY_SIZE;
rsp->init_key_dist = req->init_key_dist & remote_dist;
rsp->resp_key_dist = req->resp_key_dist & local_dist;
rsp->auth_req = (authreq & AUTH_REQ_MASK(hdev));
smp->remote_key_dist = rsp->init_key_dist;
}
static u8 check_enc_key_size(struct l2cap_conn *conn, __u8 max_key_size)
{
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp = chan->data;
if ((max_key_size > SMP_MAX_ENC_KEY_SIZE) ||
(max_key_size < SMP_MIN_ENC_KEY_SIZE))
return SMP_ENC_KEY_SIZE;
smp->enc_key_size = max_key_size;
return 0;
}
static void smp_chan_destroy(struct l2cap_conn *conn)
{
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp = chan->data;
bool complete;
BUG_ON(!smp);
cancel_delayed_work_sync(&smp->security_timer);
complete = test_bit(SMP_FLAG_COMPLETE, &smp->flags);
mgmt_smp_complete(conn->hcon, complete);
kfree(smp->csrk);
kfree(smp->slave_csrk);
kfree(smp->link_key);
crypto_free_blkcipher(smp->tfm_aes);
crypto_free_hash(smp->tfm_cmac);
/* If pairing failed clean up any keys we might have */
if (!complete) {
if (smp->ltk) {
list_del_rcu(&smp->ltk->list);
kfree_rcu(smp->ltk, rcu);
}
if (smp->slave_ltk) {
list_del_rcu(&smp->slave_ltk->list);
kfree_rcu(smp->slave_ltk, rcu);
}
if (smp->remote_irk) {
list_del_rcu(&smp->remote_irk->list);
kfree_rcu(smp->remote_irk, rcu);
}
}
chan->data = NULL;
kfree(smp);
hci_conn_drop(conn->hcon);
}
static void smp_failure(struct l2cap_conn *conn, u8 reason)
{
struct hci_conn *hcon = conn->hcon;
struct l2cap_chan *chan = conn->smp;
if (reason)
smp_send_cmd(conn, SMP_CMD_PAIRING_FAIL, sizeof(reason),
&reason);
clear_bit(HCI_CONN_ENCRYPT_PEND, &hcon->flags);
mgmt_auth_failed(hcon, HCI_ERROR_AUTH_FAILURE);
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
if (chan->data)
smp_chan_destroy(conn);
}
#define JUST_WORKS 0x00
#define JUST_CFM 0x01
#define REQ_PASSKEY 0x02
#define CFM_PASSKEY 0x03
#define REQ_OOB 0x04
#define DSP_PASSKEY 0x05
#define OVERLAP 0xFF
static const u8 gen_method[5][5] = {
{ JUST_WORKS, JUST_CFM, REQ_PASSKEY, JUST_WORKS, REQ_PASSKEY },
{ JUST_WORKS, JUST_CFM, REQ_PASSKEY, JUST_WORKS, REQ_PASSKEY },
{ CFM_PASSKEY, CFM_PASSKEY, REQ_PASSKEY, JUST_WORKS, CFM_PASSKEY },
{ JUST_WORKS, JUST_CFM, JUST_WORKS, JUST_WORKS, JUST_CFM },
{ CFM_PASSKEY, CFM_PASSKEY, REQ_PASSKEY, JUST_WORKS, OVERLAP },
};
static const u8 sc_method[5][5] = {
{ JUST_WORKS, JUST_CFM, REQ_PASSKEY, JUST_WORKS, REQ_PASSKEY },
{ JUST_WORKS, CFM_PASSKEY, REQ_PASSKEY, JUST_WORKS, CFM_PASSKEY },
{ DSP_PASSKEY, DSP_PASSKEY, REQ_PASSKEY, JUST_WORKS, DSP_PASSKEY },
{ JUST_WORKS, JUST_CFM, JUST_WORKS, JUST_WORKS, JUST_CFM },
{ DSP_PASSKEY, CFM_PASSKEY, REQ_PASSKEY, JUST_WORKS, CFM_PASSKEY },
};
static u8 get_auth_method(struct smp_chan *smp, u8 local_io, u8 remote_io)
{
/* If either side has unknown io_caps, use JUST_CFM (which gets
* converted later to JUST_WORKS if we're initiators.
*/
if (local_io > SMP_IO_KEYBOARD_DISPLAY ||
remote_io > SMP_IO_KEYBOARD_DISPLAY)
return JUST_CFM;
if (test_bit(SMP_FLAG_SC, &smp->flags))
return sc_method[remote_io][local_io];
return gen_method[remote_io][local_io];
}
static int tk_request(struct l2cap_conn *conn, u8 remote_oob, u8 auth,
u8 local_io, u8 remote_io)
{
struct hci_conn *hcon = conn->hcon;
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp = chan->data;
u32 passkey = 0;
int ret = 0;
/* Initialize key for JUST WORKS */
memset(smp->tk, 0, sizeof(smp->tk));
clear_bit(SMP_FLAG_TK_VALID, &smp->flags);
BT_DBG("tk_request: auth:%d lcl:%d rem:%d", auth, local_io, remote_io);
/* If neither side wants MITM, either "just" confirm an incoming
* request or use just-works for outgoing ones. The JUST_CFM
* will be converted to JUST_WORKS if necessary later in this
* function. If either side has MITM look up the method from the
* table.
*/
if (!(auth & SMP_AUTH_MITM))
smp->method = JUST_CFM;
else
smp->method = get_auth_method(smp, local_io, remote_io);
/* Don't confirm locally initiated pairing attempts */
if (smp->method == JUST_CFM && test_bit(SMP_FLAG_INITIATOR,
&smp->flags))
smp->method = JUST_WORKS;
/* Don't bother user space with no IO capabilities */
if (smp->method == JUST_CFM &&
hcon->io_capability == HCI_IO_NO_INPUT_OUTPUT)
smp->method = JUST_WORKS;
/* If Just Works, Continue with Zero TK */
if (smp->method == JUST_WORKS) {
set_bit(SMP_FLAG_TK_VALID, &smp->flags);
return 0;
}
/* Not Just Works/Confirm results in MITM Authentication */
if (smp->method != JUST_CFM) {
set_bit(SMP_FLAG_MITM_AUTH, &smp->flags);
if (hcon->pending_sec_level < BT_SECURITY_HIGH)
hcon->pending_sec_level = BT_SECURITY_HIGH;
}
/* If both devices have Keyoard-Display I/O, the master
* Confirms and the slave Enters the passkey.
*/
if (smp->method == OVERLAP) {
if (hcon->role == HCI_ROLE_MASTER)
smp->method = CFM_PASSKEY;
else
smp->method = REQ_PASSKEY;
}
/* Generate random passkey. */
if (smp->method == CFM_PASSKEY) {
memset(smp->tk, 0, sizeof(smp->tk));
get_random_bytes(&passkey, sizeof(passkey));
passkey %= 1000000;
put_unaligned_le32(passkey, smp->tk);
BT_DBG("PassKey: %d", passkey);
set_bit(SMP_FLAG_TK_VALID, &smp->flags);
}
if (smp->method == REQ_PASSKEY)
ret = mgmt_user_passkey_request(hcon->hdev, &hcon->dst,
hcon->type, hcon->dst_type);
else if (smp->method == JUST_CFM)
ret = mgmt_user_confirm_request(hcon->hdev, &hcon->dst,
hcon->type, hcon->dst_type,
passkey, 1);
else
ret = mgmt_user_passkey_notify(hcon->hdev, &hcon->dst,
hcon->type, hcon->dst_type,
passkey, 0);
return ret;
}
static u8 smp_confirm(struct smp_chan *smp)
{
struct l2cap_conn *conn = smp->conn;
struct smp_cmd_pairing_confirm cp;
int ret;
BT_DBG("conn %p", conn);
ret = smp_c1(smp->tfm_aes, smp->tk, smp->prnd, smp->preq, smp->prsp,
conn->hcon->init_addr_type, &conn->hcon->init_addr,
conn->hcon->resp_addr_type, &conn->hcon->resp_addr,
cp.confirm_val);
if (ret)
return SMP_UNSPECIFIED;
clear_bit(SMP_FLAG_CFM_PENDING, &smp->flags);
smp_send_cmd(smp->conn, SMP_CMD_PAIRING_CONFIRM, sizeof(cp), &cp);
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
if (conn->hcon->out)
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_CONFIRM);
else
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_RANDOM);
return 0;
}
static u8 smp_random(struct smp_chan *smp)
{
struct l2cap_conn *conn = smp->conn;
struct hci_conn *hcon = conn->hcon;
u8 confirm[16];
int ret;
if (IS_ERR_OR_NULL(smp->tfm_aes))
return SMP_UNSPECIFIED;
BT_DBG("conn %p %s", conn, conn->hcon->out ? "master" : "slave");
ret = smp_c1(smp->tfm_aes, smp->tk, smp->rrnd, smp->preq, smp->prsp,
hcon->init_addr_type, &hcon->init_addr,
hcon->resp_addr_type, &hcon->resp_addr, confirm);
if (ret)
return SMP_UNSPECIFIED;
if (memcmp(smp->pcnf, confirm, sizeof(smp->pcnf)) != 0) {
BT_ERR("Pairing failed (confirmation values mismatch)");
return SMP_CONFIRM_FAILED;
}
if (hcon->out) {
u8 stk[16];
__le64 rand = 0;
__le16 ediv = 0;
smp_s1(smp->tfm_aes, smp->tk, smp->rrnd, smp->prnd, stk);
memset(stk + smp->enc_key_size, 0,
SMP_MAX_ENC_KEY_SIZE - smp->enc_key_size);
if (test_and_set_bit(HCI_CONN_ENCRYPT_PEND, &hcon->flags))
return SMP_UNSPECIFIED;
hci_le_start_enc(hcon, ediv, rand, stk);
hcon->enc_key_size = smp->enc_key_size;
set_bit(HCI_CONN_STK_ENCRYPT, &hcon->flags);
} else {
u8 stk[16], auth;
__le64 rand = 0;
__le16 ediv = 0;
smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM, sizeof(smp->prnd),
smp->prnd);
smp_s1(smp->tfm_aes, smp->tk, smp->prnd, smp->rrnd, stk);
memset(stk + smp->enc_key_size, 0,
SMP_MAX_ENC_KEY_SIZE - smp->enc_key_size);
if (hcon->pending_sec_level == BT_SECURITY_HIGH)
auth = 1;
else
auth = 0;
/* Even though there's no _SLAVE suffix this is the
* slave STK we're adding for later lookup (the master
* STK never needs to be stored).
*/
hci_add_ltk(hcon->hdev, &hcon->dst, hcon->dst_type,
SMP_STK, auth, stk, smp->enc_key_size, ediv, rand);
}
return 0;
}
static void smp_notify_keys(struct l2cap_conn *conn)
{
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp = chan->data;
struct hci_conn *hcon = conn->hcon;
struct hci_dev *hdev = hcon->hdev;
struct smp_cmd_pairing *req = (void *) &smp->preq[1];
struct smp_cmd_pairing *rsp = (void *) &smp->prsp[1];
bool persistent;
if (smp->remote_irk) {
mgmt_new_irk(hdev, smp->remote_irk);
/* Now that user space can be considered to know the
* identity address track the connection based on it
* from now on (assuming this is an LE link).
*/
if (hcon->type == LE_LINK) {
bacpy(&hcon->dst, &smp->remote_irk->bdaddr);
hcon->dst_type = smp->remote_irk->addr_type;
queue_work(hdev->workqueue, &conn->id_addr_update_work);
}
/* When receiving an indentity resolving key for
* a remote device that does not use a resolvable
* private address, just remove the key so that
* it is possible to use the controller white
* list for scanning.
*
* Userspace will have been told to not store
* this key at this point. So it is safe to
* just remove it.
*/
if (!bacmp(&smp->remote_irk->rpa, BDADDR_ANY)) {
list_del_rcu(&smp->remote_irk->list);
kfree_rcu(smp->remote_irk, rcu);
smp->remote_irk = NULL;
}
}
if (hcon->type == ACL_LINK) {
if (hcon->key_type == HCI_LK_DEBUG_COMBINATION)
persistent = false;
else
persistent = !test_bit(HCI_CONN_FLUSH_KEY,
&hcon->flags);
} else {
/* The LTKs and CSRKs should be persistent only if both sides
* had the bonding bit set in their authentication requests.
*/
persistent = !!((req->auth_req & rsp->auth_req) &
SMP_AUTH_BONDING);
}
if (smp->csrk) {
smp->csrk->bdaddr_type = hcon->dst_type;
bacpy(&smp->csrk->bdaddr, &hcon->dst);
mgmt_new_csrk(hdev, smp->csrk, persistent);
}
if (smp->slave_csrk) {
smp->slave_csrk->bdaddr_type = hcon->dst_type;
bacpy(&smp->slave_csrk->bdaddr, &hcon->dst);
mgmt_new_csrk(hdev, smp->slave_csrk, persistent);
}
if (smp->ltk) {
smp->ltk->bdaddr_type = hcon->dst_type;
bacpy(&smp->ltk->bdaddr, &hcon->dst);
mgmt_new_ltk(hdev, smp->ltk, persistent);
}
if (smp->slave_ltk) {
smp->slave_ltk->bdaddr_type = hcon->dst_type;
bacpy(&smp->slave_ltk->bdaddr, &hcon->dst);
mgmt_new_ltk(hdev, smp->slave_ltk, persistent);
}
if (smp->link_key) {
struct link_key *key;
u8 type;
if (test_bit(SMP_FLAG_DEBUG_KEY, &smp->flags))
type = HCI_LK_DEBUG_COMBINATION;
else if (hcon->sec_level == BT_SECURITY_FIPS)
type = HCI_LK_AUTH_COMBINATION_P256;
else
type = HCI_LK_UNAUTH_COMBINATION_P256;
key = hci_add_link_key(hdev, smp->conn->hcon, &hcon->dst,
smp->link_key, type, 0, &persistent);
if (key) {
mgmt_new_link_key(hdev, key, persistent);
/* Don't keep debug keys around if the relevant
* flag is not set.
*/
if (!test_bit(HCI_KEEP_DEBUG_KEYS, &hdev->dev_flags) &&
key->type == HCI_LK_DEBUG_COMBINATION) {
list_del_rcu(&key->list);
kfree_rcu(key, rcu);
}
}
}
}
static void sc_add_ltk(struct smp_chan *smp)
{
struct hci_conn *hcon = smp->conn->hcon;
u8 key_type, auth;
if (test_bit(SMP_FLAG_DEBUG_KEY, &smp->flags))
key_type = SMP_LTK_P256_DEBUG;
else
key_type = SMP_LTK_P256;
if (hcon->pending_sec_level == BT_SECURITY_FIPS)
auth = 1;
else
auth = 0;
memset(smp->tk + smp->enc_key_size, 0,
SMP_MAX_ENC_KEY_SIZE - smp->enc_key_size);
smp->ltk = hci_add_ltk(hcon->hdev, &hcon->dst, hcon->dst_type,
key_type, auth, smp->tk, smp->enc_key_size,
0, 0);
}
static void sc_generate_link_key(struct smp_chan *smp)
{
/* These constants are as specified in the core specification.
* In ASCII they spell out to 'tmp1' and 'lebr'.
*/
const u8 tmp1[4] = { 0x31, 0x70, 0x6d, 0x74 };
const u8 lebr[4] = { 0x72, 0x62, 0x65, 0x6c };
smp->link_key = kzalloc(16, GFP_KERNEL);
if (!smp->link_key)
return;
if (smp_h6(smp->tfm_cmac, smp->tk, tmp1, smp->link_key)) {
kfree(smp->link_key);
smp->link_key = NULL;
return;
}
if (smp_h6(smp->tfm_cmac, smp->link_key, lebr, smp->link_key)) {
kfree(smp->link_key);
smp->link_key = NULL;
return;
}
}
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
static void smp_allow_key_dist(struct smp_chan *smp)
{
/* Allow the first expected phase 3 PDU. The rest of the PDUs
* will be allowed in each PDU handler to ensure we receive
* them in the correct order.
*/
if (smp->remote_key_dist & SMP_DIST_ENC_KEY)
SMP_ALLOW_CMD(smp, SMP_CMD_ENCRYPT_INFO);
else if (smp->remote_key_dist & SMP_DIST_ID_KEY)
SMP_ALLOW_CMD(smp, SMP_CMD_IDENT_INFO);
else if (smp->remote_key_dist & SMP_DIST_SIGN)
SMP_ALLOW_CMD(smp, SMP_CMD_SIGN_INFO);
}
static void sc_generate_ltk(struct smp_chan *smp)
{
/* These constants are as specified in the core specification.
* In ASCII they spell out to 'tmp2' and 'brle'.
*/
const u8 tmp2[4] = { 0x32, 0x70, 0x6d, 0x74 };
const u8 brle[4] = { 0x65, 0x6c, 0x72, 0x62 };
struct hci_conn *hcon = smp->conn->hcon;
struct hci_dev *hdev = hcon->hdev;
struct link_key *key;
key = hci_find_link_key(hdev, &hcon->dst);
if (!key) {
BT_ERR("%s No Link Key found to generate LTK", hdev->name);
return;
}
if (key->type == HCI_LK_DEBUG_COMBINATION)
set_bit(SMP_FLAG_DEBUG_KEY, &smp->flags);
if (smp_h6(smp->tfm_cmac, key->val, tmp2, smp->tk))
return;
if (smp_h6(smp->tfm_cmac, smp->tk, brle, smp->tk))
return;
sc_add_ltk(smp);
}
static void smp_distribute_keys(struct smp_chan *smp)
{
struct smp_cmd_pairing *req, *rsp;
struct l2cap_conn *conn = smp->conn;
struct hci_conn *hcon = conn->hcon;
struct hci_dev *hdev = hcon->hdev;
__u8 *keydist;
BT_DBG("conn %p", conn);
rsp = (void *) &smp->prsp[1];
/* The responder sends its keys first */
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
if (hcon->out && (smp->remote_key_dist & KEY_DIST_MASK)) {
smp_allow_key_dist(smp);
return;
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
}
req = (void *) &smp->preq[1];
if (hcon->out) {
keydist = &rsp->init_key_dist;
*keydist &= req->init_key_dist;
} else {
keydist = &rsp->resp_key_dist;
*keydist &= req->resp_key_dist;
}
if (test_bit(SMP_FLAG_SC, &smp->flags)) {
if (hcon->type == LE_LINK && (*keydist & SMP_DIST_LINK_KEY))
sc_generate_link_key(smp);
if (hcon->type == ACL_LINK && (*keydist & SMP_DIST_ENC_KEY))
sc_generate_ltk(smp);
/* Clear the keys which are generated but not distributed */
*keydist &= ~SMP_SC_NO_DIST;
}
BT_DBG("keydist 0x%x", *keydist);
if (*keydist & SMP_DIST_ENC_KEY) {
struct smp_cmd_encrypt_info enc;
struct smp_cmd_master_ident ident;
struct smp_ltk *ltk;
u8 authenticated;
__le16 ediv;
__le64 rand;
get_random_bytes(enc.ltk, sizeof(enc.ltk));
get_random_bytes(&ediv, sizeof(ediv));
get_random_bytes(&rand, sizeof(rand));
smp_send_cmd(conn, SMP_CMD_ENCRYPT_INFO, sizeof(enc), &enc);
authenticated = hcon->sec_level == BT_SECURITY_HIGH;
ltk = hci_add_ltk(hdev, &hcon->dst, hcon->dst_type,
SMP_LTK_SLAVE, authenticated, enc.ltk,
smp->enc_key_size, ediv, rand);
smp->slave_ltk = ltk;
ident.ediv = ediv;
ident.rand = rand;
smp_send_cmd(conn, SMP_CMD_MASTER_IDENT, sizeof(ident), &ident);
*keydist &= ~SMP_DIST_ENC_KEY;
}
if (*keydist & SMP_DIST_ID_KEY) {
struct smp_cmd_ident_addr_info addrinfo;
struct smp_cmd_ident_info idinfo;
memcpy(idinfo.irk, hdev->irk, sizeof(idinfo.irk));
smp_send_cmd(conn, SMP_CMD_IDENT_INFO, sizeof(idinfo), &idinfo);
/* The hci_conn contains the local identity address
* after the connection has been established.
*
* This is true even when the connection has been
* established using a resolvable random address.
*/
bacpy(&addrinfo.bdaddr, &hcon->src);
addrinfo.addr_type = hcon->src_type;
smp_send_cmd(conn, SMP_CMD_IDENT_ADDR_INFO, sizeof(addrinfo),
&addrinfo);
*keydist &= ~SMP_DIST_ID_KEY;
}
if (*keydist & SMP_DIST_SIGN) {
struct smp_cmd_sign_info sign;
struct smp_csrk *csrk;
/* Generate a new random key */
get_random_bytes(sign.csrk, sizeof(sign.csrk));
csrk = kzalloc(sizeof(*csrk), GFP_KERNEL);
if (csrk) {
csrk->master = 0x00;
memcpy(csrk->val, sign.csrk, sizeof(csrk->val));
}
smp->slave_csrk = csrk;
smp_send_cmd(conn, SMP_CMD_SIGN_INFO, sizeof(sign), &sign);
*keydist &= ~SMP_DIST_SIGN;
}
/* If there are still keys to be received wait for them */
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
if (smp->remote_key_dist & KEY_DIST_MASK) {
smp_allow_key_dist(smp);
return;
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
}
set_bit(SMP_FLAG_COMPLETE, &smp->flags);
smp_notify_keys(conn);
smp_chan_destroy(conn);
}
static void smp_timeout(struct work_struct *work)
{
struct smp_chan *smp = container_of(work, struct smp_chan,
security_timer.work);
struct l2cap_conn *conn = smp->conn;
BT_DBG("conn %p", conn);
hci_disconnect(conn->hcon, HCI_ERROR_REMOTE_USER_TERM);
}
static struct smp_chan *smp_chan_create(struct l2cap_conn *conn)
{
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp;
smp = kzalloc(sizeof(*smp), GFP_ATOMIC);
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
if (!smp)
return NULL;
smp->tfm_aes = crypto_alloc_blkcipher("ecb(aes)", 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(smp->tfm_aes)) {
BT_ERR("Unable to create ECB crypto context");
kfree(smp);
return NULL;
}
smp->tfm_cmac = crypto_alloc_hash("cmac(aes)", 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(smp->tfm_cmac)) {
BT_ERR("Unable to create CMAC crypto context");
crypto_free_blkcipher(smp->tfm_aes);
kfree(smp);
return NULL;
}
smp->conn = conn;
chan->data = smp;
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_FAIL);
INIT_DELAYED_WORK(&smp->security_timer, smp_timeout);
hci_conn_hold(conn->hcon);
return smp;
}
static int sc_mackey_and_ltk(struct smp_chan *smp, u8 mackey[16], u8 ltk[16])
{
struct hci_conn *hcon = smp->conn->hcon;
u8 *na, *nb, a[7], b[7];
if (hcon->out) {
na = smp->prnd;
nb = smp->rrnd;
} else {
na = smp->rrnd;
nb = smp->prnd;
}
memcpy(a, &hcon->init_addr, 6);
memcpy(b, &hcon->resp_addr, 6);
a[6] = hcon->init_addr_type;
b[6] = hcon->resp_addr_type;
return smp_f5(smp->tfm_cmac, smp->dhkey, na, nb, a, b, mackey, ltk);
}
static void sc_dhkey_check(struct smp_chan *smp)
{
struct hci_conn *hcon = smp->conn->hcon;
struct smp_cmd_dhkey_check check;
u8 a[7], b[7], *local_addr, *remote_addr;
u8 io_cap[3], r[16];
memcpy(a, &hcon->init_addr, 6);
memcpy(b, &hcon->resp_addr, 6);
a[6] = hcon->init_addr_type;
b[6] = hcon->resp_addr_type;
if (hcon->out) {
local_addr = a;
remote_addr = b;
memcpy(io_cap, &smp->preq[1], 3);
} else {
local_addr = b;
remote_addr = a;
memcpy(io_cap, &smp->prsp[1], 3);
}
memset(r, 0, sizeof(r));
if (smp->method == REQ_PASSKEY || smp->method == DSP_PASSKEY)
put_unaligned_le32(hcon->passkey_notify, r);
smp_f6(smp->tfm_cmac, smp->mackey, smp->prnd, smp->rrnd, r, io_cap,
local_addr, remote_addr, check.e);
smp_send_cmd(smp->conn, SMP_CMD_DHKEY_CHECK, sizeof(check), &check);
}
static u8 sc_passkey_send_confirm(struct smp_chan *smp)
{
struct l2cap_conn *conn = smp->conn;
struct hci_conn *hcon = conn->hcon;
struct smp_cmd_pairing_confirm cfm;
u8 r;
r = ((hcon->passkey_notify >> smp->passkey_round) & 0x01);
r |= 0x80;
get_random_bytes(smp->prnd, sizeof(smp->prnd));
if (smp_f4(smp->tfm_cmac, smp->local_pk, smp->remote_pk, smp->prnd, r,
cfm.confirm_val))
return SMP_UNSPECIFIED;
smp_send_cmd(conn, SMP_CMD_PAIRING_CONFIRM, sizeof(cfm), &cfm);
return 0;
}
static u8 sc_passkey_round(struct smp_chan *smp, u8 smp_op)
{
struct l2cap_conn *conn = smp->conn;
struct hci_conn *hcon = conn->hcon;
struct hci_dev *hdev = hcon->hdev;
u8 cfm[16], r;
/* Ignore the PDU if we've already done 20 rounds (0 - 19) */
if (smp->passkey_round >= 20)
return 0;
switch (smp_op) {
case SMP_CMD_PAIRING_RANDOM:
r = ((hcon->passkey_notify >> smp->passkey_round) & 0x01);
r |= 0x80;
if (smp_f4(smp->tfm_cmac, smp->remote_pk, smp->local_pk,
smp->rrnd, r, cfm))
return SMP_UNSPECIFIED;
if (memcmp(smp->pcnf, cfm, 16))
return SMP_CONFIRM_FAILED;
smp->passkey_round++;
if (smp->passkey_round == 20) {
/* Generate MacKey and LTK */
if (sc_mackey_and_ltk(smp, smp->mackey, smp->tk))
return SMP_UNSPECIFIED;
}
/* The round is only complete when the initiator
* receives pairing random.
*/
if (!hcon->out) {
smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM,
sizeof(smp->prnd), smp->prnd);
if (smp->passkey_round == 20)
SMP_ALLOW_CMD(smp, SMP_CMD_DHKEY_CHECK);
else
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_CONFIRM);
return 0;
}
/* Start the next round */
if (smp->passkey_round != 20)
return sc_passkey_round(smp, 0);
/* Passkey rounds are complete - start DHKey Check */
sc_dhkey_check(smp);
SMP_ALLOW_CMD(smp, SMP_CMD_DHKEY_CHECK);
break;
case SMP_CMD_PAIRING_CONFIRM:
if (test_bit(SMP_FLAG_WAIT_USER, &smp->flags)) {
set_bit(SMP_FLAG_CFM_PENDING, &smp->flags);
return 0;
}
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_RANDOM);
if (hcon->out) {
smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM,
sizeof(smp->prnd), smp->prnd);
return 0;
}
return sc_passkey_send_confirm(smp);
case SMP_CMD_PUBLIC_KEY:
default:
/* Initiating device starts the round */
if (!hcon->out)
return 0;
BT_DBG("%s Starting passkey round %u", hdev->name,
smp->passkey_round + 1);
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_CONFIRM);
return sc_passkey_send_confirm(smp);
}
return 0;
}
static int sc_user_reply(struct smp_chan *smp, u16 mgmt_op, __le32 passkey)
{
struct l2cap_conn *conn = smp->conn;
struct hci_conn *hcon = conn->hcon;
u8 smp_op;
clear_bit(SMP_FLAG_WAIT_USER, &smp->flags);
switch (mgmt_op) {
case MGMT_OP_USER_PASSKEY_NEG_REPLY:
smp_failure(smp->conn, SMP_PASSKEY_ENTRY_FAILED);
return 0;
case MGMT_OP_USER_CONFIRM_NEG_REPLY:
smp_failure(smp->conn, SMP_NUMERIC_COMP_FAILED);
return 0;
case MGMT_OP_USER_PASSKEY_REPLY:
hcon->passkey_notify = le32_to_cpu(passkey);
smp->passkey_round = 0;
if (test_and_clear_bit(SMP_FLAG_CFM_PENDING, &smp->flags))
smp_op = SMP_CMD_PAIRING_CONFIRM;
else
smp_op = 0;
if (sc_passkey_round(smp, smp_op))
return -EIO;
return 0;
}
/* Initiator sends DHKey check first */
if (hcon->out) {
sc_dhkey_check(smp);
SMP_ALLOW_CMD(smp, SMP_CMD_DHKEY_CHECK);
} else if (test_and_clear_bit(SMP_FLAG_DHKEY_PENDING, &smp->flags)) {
sc_dhkey_check(smp);
sc_add_ltk(smp);
}
return 0;
}
int smp_user_confirm_reply(struct hci_conn *hcon, u16 mgmt_op, __le32 passkey)
{
struct l2cap_conn *conn = hcon->l2cap_data;
struct l2cap_chan *chan;
struct smp_chan *smp;
u32 value;
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
int err;
BT_DBG("");
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
if (!conn)
return -ENOTCONN;
chan = conn->smp;
if (!chan)
return -ENOTCONN;
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
l2cap_chan_lock(chan);
if (!chan->data) {
err = -ENOTCONN;
goto unlock;
}
smp = chan->data;
if (test_bit(SMP_FLAG_SC, &smp->flags)) {
err = sc_user_reply(smp, mgmt_op, passkey);
goto unlock;
}
switch (mgmt_op) {
case MGMT_OP_USER_PASSKEY_REPLY:
value = le32_to_cpu(passkey);
memset(smp->tk, 0, sizeof(smp->tk));
BT_DBG("PassKey: %d", value);
put_unaligned_le32(value, smp->tk);
/* Fall Through */
case MGMT_OP_USER_CONFIRM_REPLY:
set_bit(SMP_FLAG_TK_VALID, &smp->flags);
break;
case MGMT_OP_USER_PASSKEY_NEG_REPLY:
case MGMT_OP_USER_CONFIRM_NEG_REPLY:
smp_failure(conn, SMP_PASSKEY_ENTRY_FAILED);
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
err = 0;
goto unlock;
default:
smp_failure(conn, SMP_PASSKEY_ENTRY_FAILED);
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
err = -EOPNOTSUPP;
goto unlock;
}
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
err = 0;
/* If it is our turn to send Pairing Confirm, do so now */
if (test_bit(SMP_FLAG_CFM_PENDING, &smp->flags)) {
u8 rsp = smp_confirm(smp);
if (rsp)
smp_failure(conn, rsp);
}
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
unlock:
l2cap_chan_unlock(chan);
return err;
}
static void build_bredr_pairing_cmd(struct smp_chan *smp,
struct smp_cmd_pairing *req,
struct smp_cmd_pairing *rsp)
{
struct l2cap_conn *conn = smp->conn;
struct hci_dev *hdev = conn->hcon->hdev;
u8 local_dist = 0, remote_dist = 0;
if (test_bit(HCI_BONDABLE, &hdev->dev_flags)) {
local_dist = SMP_DIST_ENC_KEY | SMP_DIST_SIGN;
remote_dist = SMP_DIST_ENC_KEY | SMP_DIST_SIGN;
}
if (test_bit(HCI_RPA_RESOLVING, &hdev->dev_flags))
remote_dist |= SMP_DIST_ID_KEY;
if (test_bit(HCI_PRIVACY, &hdev->dev_flags))
local_dist |= SMP_DIST_ID_KEY;
if (!rsp) {
memset(req, 0, sizeof(*req));
req->init_key_dist = local_dist;
req->resp_key_dist = remote_dist;
req->max_key_size = SMP_MAX_ENC_KEY_SIZE;
smp->remote_key_dist = remote_dist;
return;
}
memset(rsp, 0, sizeof(*rsp));
rsp->max_key_size = SMP_MAX_ENC_KEY_SIZE;
rsp->init_key_dist = req->init_key_dist & remote_dist;
rsp->resp_key_dist = req->resp_key_dist & local_dist;
smp->remote_key_dist = rsp->init_key_dist;
}
static u8 smp_cmd_pairing_req(struct l2cap_conn *conn, struct sk_buff *skb)
{
struct smp_cmd_pairing rsp, *req = (void *) skb->data;
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
struct l2cap_chan *chan = conn->smp;
struct hci_dev *hdev = conn->hcon->hdev;
struct smp_chan *smp;
u8 key_size, auth, sec_level;
int ret;
BT_DBG("conn %p", conn);
if (skb->len < sizeof(*req))
return SMP_INVALID_PARAMS;
if (conn->hcon->role != HCI_ROLE_SLAVE)
return SMP_CMD_NOTSUPP;
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
if (!chan->data)
smp = smp_chan_create(conn);
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
else
smp = chan->data;
if (!smp)
return SMP_UNSPECIFIED;
/* We didn't start the pairing, so match remote */
auth = req->auth_req & AUTH_REQ_MASK(hdev);
if (!test_bit(HCI_BONDABLE, &hdev->dev_flags) &&
(auth & SMP_AUTH_BONDING))
return SMP_PAIRING_NOTSUPP;
if (test_bit(HCI_SC_ONLY, &hdev->dev_flags) && !(auth & SMP_AUTH_SC))
return SMP_AUTH_REQUIREMENTS;
smp->preq[0] = SMP_CMD_PAIRING_REQ;
memcpy(&smp->preq[1], req, sizeof(*req));
skb_pull(skb, sizeof(*req));
/* SMP over BR/EDR requires special treatment */
if (conn->hcon->type == ACL_LINK) {
/* We must have a BR/EDR SC link */
if (!test_bit(HCI_CONN_AES_CCM, &conn->hcon->flags))
return SMP_CROSS_TRANSP_NOT_ALLOWED;
set_bit(SMP_FLAG_SC, &smp->flags);
build_bredr_pairing_cmd(smp, req, &rsp);
key_size = min(req->max_key_size, rsp.max_key_size);
if (check_enc_key_size(conn, key_size))
return SMP_ENC_KEY_SIZE;
/* Clear bits which are generated but not distributed */
smp->remote_key_dist &= ~SMP_SC_NO_DIST;
smp->prsp[0] = SMP_CMD_PAIRING_RSP;
memcpy(&smp->prsp[1], &rsp, sizeof(rsp));
smp_send_cmd(conn, SMP_CMD_PAIRING_RSP, sizeof(rsp), &rsp);
smp_distribute_keys(smp);
return 0;
}
build_pairing_cmd(conn, req, &rsp, auth);
if (rsp.auth_req & SMP_AUTH_SC)
set_bit(SMP_FLAG_SC, &smp->flags);
if (conn->hcon->io_capability == HCI_IO_NO_INPUT_OUTPUT)
sec_level = BT_SECURITY_MEDIUM;
else
sec_level = authreq_to_seclevel(auth);
if (sec_level > conn->hcon->pending_sec_level)
conn->hcon->pending_sec_level = sec_level;
/* If we need MITM check that it can be achieved */
if (conn->hcon->pending_sec_level >= BT_SECURITY_HIGH) {
u8 method;
method = get_auth_method(smp, conn->hcon->io_capability,
req->io_capability);
if (method == JUST_WORKS || method == JUST_CFM)
return SMP_AUTH_REQUIREMENTS;
}
key_size = min(req->max_key_size, rsp.max_key_size);
if (check_enc_key_size(conn, key_size))
return SMP_ENC_KEY_SIZE;
get_random_bytes(smp->prnd, sizeof(smp->prnd));
smp->prsp[0] = SMP_CMD_PAIRING_RSP;
memcpy(&smp->prsp[1], &rsp, sizeof(rsp));
smp_send_cmd(conn, SMP_CMD_PAIRING_RSP, sizeof(rsp), &rsp);
clear_bit(SMP_FLAG_INITIATOR, &smp->flags);
if (test_bit(SMP_FLAG_SC, &smp->flags)) {
SMP_ALLOW_CMD(smp, SMP_CMD_PUBLIC_KEY);
/* Clear bits which are generated but not distributed */
smp->remote_key_dist &= ~SMP_SC_NO_DIST;
/* Wait for Public Key from Initiating Device */
return 0;
} else {
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_CONFIRM);
}
/* Request setup of TK */
ret = tk_request(conn, 0, auth, rsp.io_capability, req->io_capability);
if (ret)
return SMP_UNSPECIFIED;
return 0;
}
static u8 sc_send_public_key(struct smp_chan *smp)
{
struct hci_dev *hdev = smp->conn->hcon->hdev;
BT_DBG("");
if (test_bit(HCI_USE_DEBUG_KEYS, &hdev->dev_flags)) {
BT_DBG("Using debug keys");
memcpy(smp->local_pk, debug_pk, 64);
memcpy(smp->local_sk, debug_sk, 32);
set_bit(SMP_FLAG_DEBUG_KEY, &smp->flags);
} else {
while (true) {
/* Generate local key pair for Secure Connections */
if (!ecc_make_key(smp->local_pk, smp->local_sk))
return SMP_UNSPECIFIED;
/* This is unlikely, but we need to check that
* we didn't accidentially generate a debug key.
*/
if (memcmp(smp->local_sk, debug_sk, 32))
break;
}
}
BT_DBG("Local Public Key X: %32phN", smp->local_pk);
BT_DBG("Local Public Key Y: %32phN", &smp->local_pk[32]);
BT_DBG("Local Private Key: %32phN", smp->local_sk);
smp_send_cmd(smp->conn, SMP_CMD_PUBLIC_KEY, 64, smp->local_pk);
return 0;
}
static u8 smp_cmd_pairing_rsp(struct l2cap_conn *conn, struct sk_buff *skb)
{
struct smp_cmd_pairing *req, *rsp = (void *) skb->data;
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp = chan->data;
struct hci_dev *hdev = conn->hcon->hdev;
u8 key_size, auth;
int ret;
BT_DBG("conn %p", conn);
if (skb->len < sizeof(*rsp))
return SMP_INVALID_PARAMS;
if (conn->hcon->role != HCI_ROLE_MASTER)
return SMP_CMD_NOTSUPP;
skb_pull(skb, sizeof(*rsp));
req = (void *) &smp->preq[1];
key_size = min(req->max_key_size, rsp->max_key_size);
if (check_enc_key_size(conn, key_size))
return SMP_ENC_KEY_SIZE;
auth = rsp->auth_req & AUTH_REQ_MASK(hdev);
if (test_bit(HCI_SC_ONLY, &hdev->dev_flags) && !(auth & SMP_AUTH_SC))
return SMP_AUTH_REQUIREMENTS;
smp->prsp[0] = SMP_CMD_PAIRING_RSP;
memcpy(&smp->prsp[1], rsp, sizeof(*rsp));
/* Update remote key distribution in case the remote cleared
* some bits that we had enabled in our request.
*/
smp->remote_key_dist &= rsp->resp_key_dist;
/* For BR/EDR this means we're done and can start phase 3 */
if (conn->hcon->type == ACL_LINK) {
/* Clear bits which are generated but not distributed */
smp->remote_key_dist &= ~SMP_SC_NO_DIST;
smp_distribute_keys(smp);
return 0;
}
if ((req->auth_req & SMP_AUTH_SC) && (auth & SMP_AUTH_SC))
set_bit(SMP_FLAG_SC, &smp->flags);
else if (conn->hcon->pending_sec_level > BT_SECURITY_HIGH)
conn->hcon->pending_sec_level = BT_SECURITY_HIGH;
/* If we need MITM check that it can be achieved */
if (conn->hcon->pending_sec_level >= BT_SECURITY_HIGH) {
u8 method;
method = get_auth_method(smp, req->io_capability,
rsp->io_capability);
if (method == JUST_WORKS || method == JUST_CFM)
return SMP_AUTH_REQUIREMENTS;
}
get_random_bytes(smp->prnd, sizeof(smp->prnd));
/* Update remote key distribution in case the remote cleared
* some bits that we had enabled in our request.
*/
smp->remote_key_dist &= rsp->resp_key_dist;
if (test_bit(SMP_FLAG_SC, &smp->flags)) {
/* Clear bits which are generated but not distributed */
smp->remote_key_dist &= ~SMP_SC_NO_DIST;
SMP_ALLOW_CMD(smp, SMP_CMD_PUBLIC_KEY);
return sc_send_public_key(smp);
}
auth |= req->auth_req;
ret = tk_request(conn, 0, auth, req->io_capability, rsp->io_capability);
if (ret)
return SMP_UNSPECIFIED;
set_bit(SMP_FLAG_CFM_PENDING, &smp->flags);
/* Can't compose response until we have been confirmed */
if (test_bit(SMP_FLAG_TK_VALID, &smp->flags))
return smp_confirm(smp);
return 0;
}
static u8 sc_check_confirm(struct smp_chan *smp)
{
struct l2cap_conn *conn = smp->conn;
BT_DBG("");
/* Public Key exchange must happen before any other steps */
if (!test_bit(SMP_FLAG_REMOTE_PK, &smp->flags))
return SMP_UNSPECIFIED;
if (smp->method == REQ_PASSKEY || smp->method == DSP_PASSKEY)
return sc_passkey_round(smp, SMP_CMD_PAIRING_CONFIRM);
if (conn->hcon->out) {
smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM, sizeof(smp->prnd),
smp->prnd);
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_RANDOM);
}
return 0;
}
static u8 smp_cmd_pairing_confirm(struct l2cap_conn *conn, struct sk_buff *skb)
{
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp = chan->data;
BT_DBG("conn %p %s", conn, conn->hcon->out ? "master" : "slave");
if (skb->len < sizeof(smp->pcnf))
return SMP_INVALID_PARAMS;
memcpy(smp->pcnf, skb->data, sizeof(smp->pcnf));
skb_pull(skb, sizeof(smp->pcnf));
if (test_bit(SMP_FLAG_SC, &smp->flags))
return sc_check_confirm(smp);
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
if (conn->hcon->out) {
smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM, sizeof(smp->prnd),
smp->prnd);
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_RANDOM);
return 0;
}
if (test_bit(SMP_FLAG_TK_VALID, &smp->flags))
return smp_confirm(smp);
else
set_bit(SMP_FLAG_CFM_PENDING, &smp->flags);
return 0;
}
static u8 smp_cmd_pairing_random(struct l2cap_conn *conn, struct sk_buff *skb)
{
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp = chan->data;
struct hci_conn *hcon = conn->hcon;
u8 *pkax, *pkbx, *na, *nb;
u32 passkey;
int err;
BT_DBG("conn %p", conn);
if (skb->len < sizeof(smp->rrnd))
return SMP_INVALID_PARAMS;
memcpy(smp->rrnd, skb->data, sizeof(smp->rrnd));
skb_pull(skb, sizeof(smp->rrnd));
if (!test_bit(SMP_FLAG_SC, &smp->flags))
return smp_random(smp);
/* Passkey entry has special treatment */
if (smp->method == REQ_PASSKEY || smp->method == DSP_PASSKEY)
return sc_passkey_round(smp, SMP_CMD_PAIRING_RANDOM);
if (hcon->out) {
u8 cfm[16];
err = smp_f4(smp->tfm_cmac, smp->remote_pk, smp->local_pk,
smp->rrnd, 0, cfm);
if (err)
return SMP_UNSPECIFIED;
if (memcmp(smp->pcnf, cfm, 16))
return SMP_CONFIRM_FAILED;
pkax = smp->local_pk;
pkbx = smp->remote_pk;
na = smp->prnd;
nb = smp->rrnd;
} else {
smp_send_cmd(conn, SMP_CMD_PAIRING_RANDOM, sizeof(smp->prnd),
smp->prnd);
SMP_ALLOW_CMD(smp, SMP_CMD_DHKEY_CHECK);
pkax = smp->remote_pk;
pkbx = smp->local_pk;
na = smp->rrnd;
nb = smp->prnd;
}
/* Generate MacKey and LTK */
err = sc_mackey_and_ltk(smp, smp->mackey, smp->tk);
if (err)
return SMP_UNSPECIFIED;
if (smp->method == JUST_WORKS) {
if (hcon->out) {
sc_dhkey_check(smp);
SMP_ALLOW_CMD(smp, SMP_CMD_DHKEY_CHECK);
}
return 0;
}
err = smp_g2(smp->tfm_cmac, pkax, pkbx, na, nb, &passkey);
if (err)
return SMP_UNSPECIFIED;
err = mgmt_user_confirm_request(hcon->hdev, &hcon->dst, hcon->type,
hcon->dst_type, passkey, 0);
if (err)
return SMP_UNSPECIFIED;
set_bit(SMP_FLAG_WAIT_USER, &smp->flags);
return 0;
}
static bool smp_ltk_encrypt(struct l2cap_conn *conn, u8 sec_level)
{
struct smp_ltk *key;
struct hci_conn *hcon = conn->hcon;
key = hci_find_ltk(hcon->hdev, &hcon->dst, hcon->dst_type, hcon->role);
if (!key)
return false;
if (smp_ltk_sec_level(key) < sec_level)
return false;
if (test_and_set_bit(HCI_CONN_ENCRYPT_PEND, &hcon->flags))
return true;
hci_le_start_enc(hcon, key->ediv, key->rand, key->val);
hcon->enc_key_size = key->enc_size;
/* We never store STKs for master role, so clear this flag */
clear_bit(HCI_CONN_STK_ENCRYPT, &hcon->flags);
return true;
}
bool smp_sufficient_security(struct hci_conn *hcon, u8 sec_level,
enum smp_key_pref key_pref)
{
if (sec_level == BT_SECURITY_LOW)
return true;
/* If we're encrypted with an STK but the caller prefers using
* LTK claim insufficient security. This way we allow the
* connection to be re-encrypted with an LTK, even if the LTK
* provides the same level of security. Only exception is if we
* don't have an LTK (e.g. because of key distribution bits).
*/
if (key_pref == SMP_USE_LTK &&
test_bit(HCI_CONN_STK_ENCRYPT, &hcon->flags) &&
hci_find_ltk(hcon->hdev, &hcon->dst, hcon->dst_type, hcon->role))
return false;
if (hcon->sec_level >= sec_level)
return true;
return false;
}
static u8 smp_cmd_security_req(struct l2cap_conn *conn, struct sk_buff *skb)
{
struct smp_cmd_security_req *rp = (void *) skb->data;
struct smp_cmd_pairing cp;
struct hci_conn *hcon = conn->hcon;
struct hci_dev *hdev = hcon->hdev;
struct smp_chan *smp;
u8 sec_level, auth;
BT_DBG("conn %p", conn);
if (skb->len < sizeof(*rp))
return SMP_INVALID_PARAMS;
if (hcon->role != HCI_ROLE_MASTER)
return SMP_CMD_NOTSUPP;
auth = rp->auth_req & AUTH_REQ_MASK(hdev);
if (test_bit(HCI_SC_ONLY, &hdev->dev_flags) && !(auth & SMP_AUTH_SC))
return SMP_AUTH_REQUIREMENTS;
if (hcon->io_capability == HCI_IO_NO_INPUT_OUTPUT)
sec_level = BT_SECURITY_MEDIUM;
else
sec_level = authreq_to_seclevel(auth);
if (smp_sufficient_security(hcon, sec_level, SMP_USE_LTK))
return 0;
if (sec_level > hcon->pending_sec_level)
hcon->pending_sec_level = sec_level;
if (smp_ltk_encrypt(conn, hcon->pending_sec_level))
return 0;
smp = smp_chan_create(conn);
if (!smp)
return SMP_UNSPECIFIED;
if (!test_bit(HCI_BONDABLE, &hcon->hdev->dev_flags) &&
(auth & SMP_AUTH_BONDING))
Bluetooth: Fix SMP context tracking leading to a kernel crash The HCI_CONN_LE_SMP_PEND flag is supposed to indicate whether we have an SMP context or not. If the context creation fails, or some other error is indicated between setting the flag and creating the context the flag must be cleared first. This patch ensures that smp_chan_create() clears the flag in case of allocation failure as well as reorders code in smp_cmd_security_req() that could lead to returning an error between setting the flag and creating the context. Without the patch the following kind of kernel crash could be observed (this one because of unacceptable authentication requirements in a Security Request): [ +0.000855] kernel BUG at net/bluetooth/smp.c:606! [ +0.000000] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC [ +0.000000] CPU: 0 PID: 58 Comm: kworker/u5:2 Tainted: G W 3.16.0-rc1+ #785 [ +0.008391] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ +0.000000] Workqueue: hci0 hci_rx_work [ +0.000000] task: f4dc8f90 ti: f4ef0000 task.ti: f4ef0000 [ +0.000000] EIP: 0060:[<c13432b6>] EFLAGS: 00010246 CPU: 0 [ +0.000000] EIP is at smp_chan_destroy+0x1e/0x145 [ +0.000709] EAX: f46db870 EBX: 00000000 ECX: 00000000 EDX: 00000005 [ +0.000000] ESI: f46db870 EDI: f46db870 EBP: f4ef1dc0 ESP: f4ef1db0 [ +0.000000] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 [ +0.000000] CR0: 8005003b CR2: b666b0b0 CR3: 00022000 CR4: 00000690 [ +0.000000] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 [ +0.000000] DR6: fffe0ff0 DR7: 00000400 [ +0.000000] Stack: [ +0.000000] 00000005 f17b7840 f46db870 f4ef1dd4 f4ef1de4 c1343441 c134342e 00000000 [ +0.000000] c1343441 00000005 00000002 00000000 f17b7840 f4ef1e38 c134452a 00002aae [ +0.000000] 01ef1e00 00002aae f46bd980 f46db870 00000039 ffffffff 00000007 f4ef1e34 [ +0.000000] Call Trace: [ +0.000000] [<c1343441>] smp_failure+0x64/0x6c [ +0.000000] [<c134342e>] ? smp_failure+0x51/0x6c [ +0.000000] [<c1343441>] ? smp_failure+0x64/0x6c [ +0.000000] [<c134452a>] smp_sig_channel+0xad6/0xafc [ +0.000000] [<c1053b61>] ? vprintk_emit+0x343/0x366 [ +0.000000] [<c133f34e>] l2cap_recv_frame+0x1337/0x1ac4 [ +0.000000] [<c133f34e>] ? l2cap_recv_frame+0x1337/0x1ac4 [ +0.000000] [<c1172307>] ? __dynamic_pr_debug+0x3e/0x40 [ +0.000000] [<c11702a1>] ? debug_smp_processor_id+0x12/0x14 [ +0.000000] [<c1340bc9>] l2cap_recv_acldata+0xe8/0x239 [ +0.000000] [<c1340bc9>] ? l2cap_recv_acldata+0xe8/0x239 [ +0.000000] [<c1169931>] ? __const_udelay+0x1a/0x1c [ +0.000000] [<c131f120>] hci_rx_work+0x1a1/0x286 [ +0.000000] [<c137244e>] ? mutex_unlock+0x8/0xa [ +0.000000] [<c131f120>] ? hci_rx_work+0x1a1/0x286 [ +0.000000] [<c1038fe5>] process_one_work+0x128/0x1df [ +0.000000] [<c1038fe5>] ? process_one_work+0x128/0x1df [ +0.000000] [<c10392df>] worker_thread+0x222/0x2de [ +0.000000] [<c10390bd>] ? process_scheduled_works+0x21/0x21 [ +0.000000] [<c103d34c>] kthread+0x82/0x87 [ +0.000000] [<c1040000>] ? create_new_namespaces+0x90/0x105 [ +0.000000] [<c13738e1>] ret_from_kernel_thread+0x21/0x30 [ +0.000000] [<c103d2ca>] ? __kthread_parkme+0x50/0x50 [ +0.000000] Code: 65 f4 89 f0 5b 5e 5f 5d 8d 67 f8 5f c3 57 8d 7c 24 08 83 e4 f8 ff 77 fc 55 89 e5 57 89 c7 56 53 52 8b 98 e0 00 00 00 85 db 75 02 <0f> 0b 8b b3 80 00 00 00 8b 00 c1 ee 03 83 e6 01 89 f2 e8 ef 09 [ +0.000000] EIP: [<c13432b6>] smp_chan_destroy+0x1e/0x145 SS:ESP 0068:f4ef1db0 Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-07-29 19:18:48 +08:00
return SMP_PAIRING_NOTSUPP;
skb_pull(skb, sizeof(*rp));
memset(&cp, 0, sizeof(cp));
build_pairing_cmd(conn, &cp, NULL, auth);
smp->preq[0] = SMP_CMD_PAIRING_REQ;
memcpy(&smp->preq[1], &cp, sizeof(cp));
smp_send_cmd(conn, SMP_CMD_PAIRING_REQ, sizeof(cp), &cp);
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_RSP);
return 0;
}
int smp_conn_security(struct hci_conn *hcon, __u8 sec_level)
{
struct l2cap_conn *conn = hcon->l2cap_data;
struct l2cap_chan *chan;
Bluetooth: Fix potential NULL pointer dereference in SMP If a sudden disconnection happens the l2cap_conn pointer may already have been cleaned up by the time hci_conn_security gets called, resulting in the following oops if we don't have a proper NULL check: BUG: unable to handle kernel NULL pointer dereference at 000000c8 IP: [<c132e2ed>] smp_conn_security+0x26/0x151 *pde = 00000000 Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC CPU: 1 PID: 673 Comm: memcheck-x86-li Not tainted 3.14.0-rc2+ #437 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 task: f0ef0520 ti: f0d6a000 task.ti: f0d6a000 EIP: 0060:[<c132e2ed>] EFLAGS: 00010246 CPU: 1 EIP is at smp_conn_security+0x26/0x151 EAX: f0ec1770 EBX: f0ec1770 ECX: 00000002 EDX: 00000002 ESI: 00000002 EDI: 00000000 EBP: f0d6bdc0 ESP: f0d6bda0 DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 CR0: 80050033 CR2: 000000c8 CR3: 30f0f000 CR4: 00000690 Stack: f4f55000 00000002 f0d6bdcc c1097a2b c1319f40 f0ec1770 00000002 f0d6bdd0 f0d6bde8 c1312a82 f0d6bdfc c1312a82 c1319f84 00000008 f4d81c20 f0e5fd86 f0ec1770 f0d6bdfc f0d6be28 c131be3b c131bdc1 f0d25270 c131be3b 00000008 Call Trace: [<c1097a2b>] ? __kmalloc+0x118/0x128 [<c1319f40>] ? mgmt_pending_add+0x49/0x9b [<c1312a82>] hci_conn_security+0x4a/0x1dd [<c1312a82>] ? hci_conn_security+0x4a/0x1dd [<c1319f84>] ? mgmt_pending_add+0x8d/0x9b [<c131be3b>] pair_device+0x1e1/0x206 [<c131bdc1>] ? pair_device+0x167/0x206 [<c131be3b>] ? pair_device+0x1e1/0x206 [<c131ed44>] mgmt_control+0x275/0x2d6 Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-03-24 20:39:03 +08:00
struct smp_chan *smp;
__u8 authreq;
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
int ret;
BT_DBG("conn %p hcon %p level 0x%2.2x", conn, hcon, sec_level);
Bluetooth: Fix potential NULL pointer dereference in SMP If a sudden disconnection happens the l2cap_conn pointer may already have been cleaned up by the time hci_conn_security gets called, resulting in the following oops if we don't have a proper NULL check: BUG: unable to handle kernel NULL pointer dereference at 000000c8 IP: [<c132e2ed>] smp_conn_security+0x26/0x151 *pde = 00000000 Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC CPU: 1 PID: 673 Comm: memcheck-x86-li Not tainted 3.14.0-rc2+ #437 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 task: f0ef0520 ti: f0d6a000 task.ti: f0d6a000 EIP: 0060:[<c132e2ed>] EFLAGS: 00010246 CPU: 1 EIP is at smp_conn_security+0x26/0x151 EAX: f0ec1770 EBX: f0ec1770 ECX: 00000002 EDX: 00000002 ESI: 00000002 EDI: 00000000 EBP: f0d6bdc0 ESP: f0d6bda0 DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 CR0: 80050033 CR2: 000000c8 CR3: 30f0f000 CR4: 00000690 Stack: f4f55000 00000002 f0d6bdcc c1097a2b c1319f40 f0ec1770 00000002 f0d6bdd0 f0d6bde8 c1312a82 f0d6bdfc c1312a82 c1319f84 00000008 f4d81c20 f0e5fd86 f0ec1770 f0d6bdfc f0d6be28 c131be3b c131bdc1 f0d25270 c131be3b 00000008 Call Trace: [<c1097a2b>] ? __kmalloc+0x118/0x128 [<c1319f40>] ? mgmt_pending_add+0x49/0x9b [<c1312a82>] hci_conn_security+0x4a/0x1dd [<c1312a82>] ? hci_conn_security+0x4a/0x1dd [<c1319f84>] ? mgmt_pending_add+0x8d/0x9b [<c131be3b>] pair_device+0x1e1/0x206 [<c131bdc1>] ? pair_device+0x167/0x206 [<c131be3b>] ? pair_device+0x1e1/0x206 [<c131ed44>] mgmt_control+0x275/0x2d6 Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-03-24 20:39:03 +08:00
/* This may be NULL if there's an unexpected disconnection */
if (!conn)
return 1;
chan = conn->smp;
if (!test_bit(HCI_LE_ENABLED, &hcon->hdev->dev_flags))
return 1;
if (smp_sufficient_security(hcon, sec_level, SMP_USE_LTK))
return 1;
if (sec_level > hcon->pending_sec_level)
hcon->pending_sec_level = sec_level;
if (hcon->role == HCI_ROLE_MASTER)
if (smp_ltk_encrypt(conn, hcon->pending_sec_level))
return 0;
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
l2cap_chan_lock(chan);
/* If SMP is already in progress ignore this request */
if (chan->data) {
ret = 0;
goto unlock;
}
smp = smp_chan_create(conn);
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
if (!smp) {
ret = 1;
goto unlock;
}
authreq = seclevel_to_authreq(sec_level);
if (test_bit(HCI_SC_ENABLED, &hcon->hdev->dev_flags))
authreq |= SMP_AUTH_SC;
/* Require MITM if IO Capability allows or the security level
* requires it.
*/
if (hcon->io_capability != HCI_IO_NO_INPUT_OUTPUT ||
hcon->pending_sec_level > BT_SECURITY_MEDIUM)
authreq |= SMP_AUTH_MITM;
if (hcon->role == HCI_ROLE_MASTER) {
struct smp_cmd_pairing cp;
build_pairing_cmd(conn, &cp, NULL, authreq);
smp->preq[0] = SMP_CMD_PAIRING_REQ;
memcpy(&smp->preq[1], &cp, sizeof(cp));
smp_send_cmd(conn, SMP_CMD_PAIRING_REQ, sizeof(cp), &cp);
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_RSP);
} else {
struct smp_cmd_security_req cp;
cp.auth_req = authreq;
smp_send_cmd(conn, SMP_CMD_SECURITY_REQ, sizeof(cp), &cp);
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_REQ);
}
set_bit(SMP_FLAG_INITIATOR, &smp->flags);
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
ret = 0;
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
unlock:
l2cap_chan_unlock(chan);
return ret;
}
static int smp_cmd_encrypt_info(struct l2cap_conn *conn, struct sk_buff *skb)
{
struct smp_cmd_encrypt_info *rp = (void *) skb->data;
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp = chan->data;
BT_DBG("conn %p", conn);
if (skb->len < sizeof(*rp))
return SMP_INVALID_PARAMS;
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
SMP_ALLOW_CMD(smp, SMP_CMD_MASTER_IDENT);
skb_pull(skb, sizeof(*rp));
memcpy(smp->tk, rp->ltk, sizeof(smp->tk));
return 0;
}
static int smp_cmd_master_ident(struct l2cap_conn *conn, struct sk_buff *skb)
{
struct smp_cmd_master_ident *rp = (void *) skb->data;
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp = chan->data;
struct hci_dev *hdev = conn->hcon->hdev;
struct hci_conn *hcon = conn->hcon;
struct smp_ltk *ltk;
u8 authenticated;
BT_DBG("conn %p", conn);
if (skb->len < sizeof(*rp))
return SMP_INVALID_PARAMS;
/* Mark the information as received */
smp->remote_key_dist &= ~SMP_DIST_ENC_KEY;
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
if (smp->remote_key_dist & SMP_DIST_ID_KEY)
SMP_ALLOW_CMD(smp, SMP_CMD_IDENT_INFO);
else if (smp->remote_key_dist & SMP_DIST_SIGN)
SMP_ALLOW_CMD(smp, SMP_CMD_SIGN_INFO);
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
skb_pull(skb, sizeof(*rp));
authenticated = (hcon->sec_level == BT_SECURITY_HIGH);
ltk = hci_add_ltk(hdev, &hcon->dst, hcon->dst_type, SMP_LTK,
authenticated, smp->tk, smp->enc_key_size,
rp->ediv, rp->rand);
smp->ltk = ltk;
if (!(smp->remote_key_dist & KEY_DIST_MASK))
smp_distribute_keys(smp);
return 0;
}
static int smp_cmd_ident_info(struct l2cap_conn *conn, struct sk_buff *skb)
{
struct smp_cmd_ident_info *info = (void *) skb->data;
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp = chan->data;
BT_DBG("");
if (skb->len < sizeof(*info))
return SMP_INVALID_PARAMS;
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
SMP_ALLOW_CMD(smp, SMP_CMD_IDENT_ADDR_INFO);
skb_pull(skb, sizeof(*info));
memcpy(smp->irk, info->irk, 16);
return 0;
}
static int smp_cmd_ident_addr_info(struct l2cap_conn *conn,
struct sk_buff *skb)
{
struct smp_cmd_ident_addr_info *info = (void *) skb->data;
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp = chan->data;
struct hci_conn *hcon = conn->hcon;
bdaddr_t rpa;
BT_DBG("");
if (skb->len < sizeof(*info))
return SMP_INVALID_PARAMS;
/* Mark the information as received */
smp->remote_key_dist &= ~SMP_DIST_ID_KEY;
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
if (smp->remote_key_dist & SMP_DIST_SIGN)
SMP_ALLOW_CMD(smp, SMP_CMD_SIGN_INFO);
skb_pull(skb, sizeof(*info));
/* Strictly speaking the Core Specification (4.1) allows sending
* an empty address which would force us to rely on just the IRK
* as "identity information". However, since such
* implementations are not known of and in order to not over
* complicate our implementation, simply pretend that we never
* received an IRK for such a device.
*/
if (!bacmp(&info->bdaddr, BDADDR_ANY)) {
BT_ERR("Ignoring IRK with no identity address");
goto distribute;
}
bacpy(&smp->id_addr, &info->bdaddr);
smp->id_addr_type = info->addr_type;
if (hci_bdaddr_is_rpa(&hcon->dst, hcon->dst_type))
bacpy(&rpa, &hcon->dst);
else
bacpy(&rpa, BDADDR_ANY);
smp->remote_irk = hci_add_irk(conn->hcon->hdev, &smp->id_addr,
smp->id_addr_type, smp->irk, &rpa);
distribute:
if (!(smp->remote_key_dist & KEY_DIST_MASK))
smp_distribute_keys(smp);
return 0;
}
static int smp_cmd_sign_info(struct l2cap_conn *conn, struct sk_buff *skb)
{
struct smp_cmd_sign_info *rp = (void *) skb->data;
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp = chan->data;
struct smp_csrk *csrk;
BT_DBG("conn %p", conn);
if (skb->len < sizeof(*rp))
return SMP_INVALID_PARAMS;
/* Mark the information as received */
smp->remote_key_dist &= ~SMP_DIST_SIGN;
skb_pull(skb, sizeof(*rp));
csrk = kzalloc(sizeof(*csrk), GFP_KERNEL);
if (csrk) {
csrk->master = 0x01;
memcpy(csrk->val, rp->csrk, sizeof(csrk->val));
}
smp->csrk = csrk;
smp_distribute_keys(smp);
return 0;
}
static u8 sc_select_method(struct smp_chan *smp)
{
struct l2cap_conn *conn = smp->conn;
struct hci_conn *hcon = conn->hcon;
struct smp_cmd_pairing *local, *remote;
u8 local_mitm, remote_mitm, local_io, remote_io, method;
/* The preq/prsp contain the raw Pairing Request/Response PDUs
* which are needed as inputs to some crypto functions. To get
* the "struct smp_cmd_pairing" from them we need to skip the
* first byte which contains the opcode.
*/
if (hcon->out) {
local = (void *) &smp->preq[1];
remote = (void *) &smp->prsp[1];
} else {
local = (void *) &smp->prsp[1];
remote = (void *) &smp->preq[1];
}
local_io = local->io_capability;
remote_io = remote->io_capability;
local_mitm = (local->auth_req & SMP_AUTH_MITM);
remote_mitm = (remote->auth_req & SMP_AUTH_MITM);
/* If either side wants MITM, look up the method from the table,
* otherwise use JUST WORKS.
*/
if (local_mitm || remote_mitm)
method = get_auth_method(smp, local_io, remote_io);
else
method = JUST_WORKS;
/* Don't confirm locally initiated pairing attempts */
if (method == JUST_CFM && test_bit(SMP_FLAG_INITIATOR, &smp->flags))
method = JUST_WORKS;
return method;
}
static int smp_cmd_public_key(struct l2cap_conn *conn, struct sk_buff *skb)
{
struct smp_cmd_public_key *key = (void *) skb->data;
struct hci_conn *hcon = conn->hcon;
struct l2cap_chan *chan = conn->smp;
struct smp_chan *smp = chan->data;
struct hci_dev *hdev = hcon->hdev;
struct smp_cmd_pairing_confirm cfm;
int err;
BT_DBG("conn %p", conn);
if (skb->len < sizeof(*key))
return SMP_INVALID_PARAMS;
memcpy(smp->remote_pk, key, 64);
/* Non-initiating device sends its public key after receiving
* the key from the initiating device.
*/
if (!hcon->out) {
err = sc_send_public_key(smp);
if (err)
return err;
}
BT_DBG("Remote Public Key X: %32phN", smp->remote_pk);
BT_DBG("Remote Public Key Y: %32phN", &smp->remote_pk[32]);
if (!ecdh_shared_secret(smp->remote_pk, smp->local_sk, smp->dhkey))
return SMP_UNSPECIFIED;
BT_DBG("DHKey %32phN", smp->dhkey);
set_bit(SMP_FLAG_REMOTE_PK, &smp->flags);
smp->method = sc_select_method(smp);
BT_DBG("%s selected method 0x%02x", hdev->name, smp->method);
/* JUST_WORKS and JUST_CFM result in an unauthenticated key */
if (smp->method == JUST_WORKS || smp->method == JUST_CFM)
hcon->pending_sec_level = BT_SECURITY_MEDIUM;
else
hcon->pending_sec_level = BT_SECURITY_FIPS;
if (!memcmp(debug_pk, smp->remote_pk, 64))
set_bit(SMP_FLAG_DEBUG_KEY, &smp->flags);
if (smp->method == DSP_PASSKEY) {
get_random_bytes(&hcon->passkey_notify,
sizeof(hcon->passkey_notify));
hcon->passkey_notify %= 1000000;
hcon->passkey_entered = 0;
smp->passkey_round = 0;
if (mgmt_user_passkey_notify(hdev, &hcon->dst, hcon->type,
hcon->dst_type,
hcon->passkey_notify,
hcon->passkey_entered))
return SMP_UNSPECIFIED;
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_CONFIRM);
return sc_passkey_round(smp, SMP_CMD_PUBLIC_KEY);
}
if (hcon->out)
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_CONFIRM);
if (smp->method == REQ_PASSKEY) {
if (mgmt_user_passkey_request(hdev, &hcon->dst, hcon->type,
hcon->dst_type))
return SMP_UNSPECIFIED;
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_CONFIRM);
set_bit(SMP_FLAG_WAIT_USER, &smp->flags);
return 0;
}
/* The Initiating device waits for the non-initiating device to
* send the confirm value.
*/
if (conn->hcon->out)
return 0;
err = smp_f4(smp->tfm_cmac, smp->local_pk, smp->remote_pk, smp->prnd,
0, cfm.confirm_val);
if (err)
return SMP_UNSPECIFIED;
smp_send_cmd(conn, SMP_CMD_PAIRING_CONFIRM, sizeof(cfm), &cfm);
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_RANDOM);
return 0;
}
static int smp_cmd_dhkey_check(struct l2cap_conn *conn, struct sk_buff *skb)
{
struct smp_cmd_dhkey_check *check = (void *) skb->data;
struct l2cap_chan *chan = conn->smp;
struct hci_conn *hcon = conn->hcon;
struct smp_chan *smp = chan->data;
u8 a[7], b[7], *local_addr, *remote_addr;
u8 io_cap[3], r[16], e[16];
int err;
BT_DBG("conn %p", conn);
if (skb->len < sizeof(*check))
return SMP_INVALID_PARAMS;
memcpy(a, &hcon->init_addr, 6);
memcpy(b, &hcon->resp_addr, 6);
a[6] = hcon->init_addr_type;
b[6] = hcon->resp_addr_type;
if (hcon->out) {
local_addr = a;
remote_addr = b;
memcpy(io_cap, &smp->prsp[1], 3);
} else {
local_addr = b;
remote_addr = a;
memcpy(io_cap, &smp->preq[1], 3);
}
memset(r, 0, sizeof(r));
if (smp->method == REQ_PASSKEY || smp->method == DSP_PASSKEY)
put_unaligned_le32(hcon->passkey_notify, r);
err = smp_f6(smp->tfm_cmac, smp->mackey, smp->rrnd, smp->prnd, r,
io_cap, remote_addr, local_addr, e);
if (err)
return SMP_UNSPECIFIED;
if (memcmp(check->e, e, 16))
return SMP_DHKEY_CHECK_FAILED;
if (!hcon->out) {
if (test_bit(SMP_FLAG_WAIT_USER, &smp->flags)) {
set_bit(SMP_FLAG_DHKEY_PENDING, &smp->flags);
return 0;
}
/* Slave sends DHKey check as response to master */
sc_dhkey_check(smp);
}
sc_add_ltk(smp);
if (hcon->out) {
hci_le_start_enc(hcon, 0, 0, smp->tk);
hcon->enc_key_size = smp->enc_key_size;
}
return 0;
}
static int smp_cmd_keypress_notify(struct l2cap_conn *conn,
struct sk_buff *skb)
{
struct smp_cmd_keypress_notify *kp = (void *) skb->data;
BT_DBG("value 0x%02x", kp->value);
return 0;
}
static int smp_sig_channel(struct l2cap_chan *chan, struct sk_buff *skb)
{
struct l2cap_conn *conn = chan->conn;
struct hci_conn *hcon = conn->hcon;
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
struct smp_chan *smp;
__u8 code, reason;
int err = 0;
if (skb->len < 1)
return -EILSEQ;
if (!test_bit(HCI_LE_ENABLED, &hcon->hdev->dev_flags)) {
reason = SMP_PAIRING_NOTSUPP;
goto done;
}
code = skb->data[0];
skb_pull(skb, sizeof(code));
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
smp = chan->data;
if (code > SMP_CMD_MAX)
goto drop;
if (smp && !test_and_clear_bit(code, &smp->allow_cmd))
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
goto drop;
/* If we don't have a context the only allowed commands are
* pairing request and security request.
*/
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
if (!smp && code != SMP_CMD_PAIRING_REQ && code != SMP_CMD_SECURITY_REQ)
goto drop;
switch (code) {
case SMP_CMD_PAIRING_REQ:
reason = smp_cmd_pairing_req(conn, skb);
break;
case SMP_CMD_PAIRING_FAIL:
smp_failure(conn, 0);
err = -EPERM;
break;
case SMP_CMD_PAIRING_RSP:
reason = smp_cmd_pairing_rsp(conn, skb);
break;
case SMP_CMD_SECURITY_REQ:
reason = smp_cmd_security_req(conn, skb);
break;
case SMP_CMD_PAIRING_CONFIRM:
reason = smp_cmd_pairing_confirm(conn, skb);
break;
case SMP_CMD_PAIRING_RANDOM:
reason = smp_cmd_pairing_random(conn, skb);
break;
case SMP_CMD_ENCRYPT_INFO:
reason = smp_cmd_encrypt_info(conn, skb);
break;
case SMP_CMD_MASTER_IDENT:
reason = smp_cmd_master_ident(conn, skb);
break;
case SMP_CMD_IDENT_INFO:
reason = smp_cmd_ident_info(conn, skb);
break;
case SMP_CMD_IDENT_ADDR_INFO:
reason = smp_cmd_ident_addr_info(conn, skb);
break;
case SMP_CMD_SIGN_INFO:
reason = smp_cmd_sign_info(conn, skb);
break;
case SMP_CMD_PUBLIC_KEY:
reason = smp_cmd_public_key(conn, skb);
break;
case SMP_CMD_DHKEY_CHECK:
reason = smp_cmd_dhkey_check(conn, skb);
break;
case SMP_CMD_KEYPRESS_NOTIFY:
reason = smp_cmd_keypress_notify(conn, skb);
break;
default:
BT_DBG("Unknown command code 0x%2.2x", code);
reason = SMP_CMD_NOTSUPP;
goto done;
}
done:
if (!err) {
if (reason)
smp_failure(conn, reason);
kfree_skb(skb);
}
return err;
Bluetooth: Add strict checks for allowed SMP PDUs SMP defines quite clearly when certain PDUs are to be expected/allowed and when not, but doesn't have any explicit request/response definition. So far the code has relied on each PDU handler to behave correctly if receiving PDUs at an unexpected moment, however this requires many different checks and is prone to errors. This patch introduces a generic way to keep track of allowed PDUs and thereby reduces the responsibility & load on individual command handlers. The tracking is implemented using a simple bit-mask where each opcode maps to its own bit. If the bit is set the corresponding PDU is allow and if the bit is not set the PDU is not allowed. As a simple example, when we send the Pairing Request we'd set the bit for Pairing Response, and when we receive the Pairing Response we'd clear the bit for Pairing Response. Since the disallowed PDU rejection is now done in a single central place we need to be a bit careful of which action makes most sense to all cases. Previously some, such as Security Request, have been simply ignored whereas others have caused an explicit disconnect. The only PDU rejection action that keeps good interoperability and can be used for all the applicable use cases is to drop the data. This may raise some concerns of us now being more lenient for misbehaving (and potentially malicious) devices, but the policy of simply dropping data has been a successful one for many years e.g. in L2CAP (where this is the *only* policy for such cases - we never request disconnection in l2cap_core.c because of bad data). Furthermore, we cannot prevent connected devices from creating the SMP context (through a Security or Pairing Request), and once the context exists looking up the corresponding bit for the received opcode and deciding to reject it is essentially an equally lightweight operation as the kind of rejection that l2cap_core.c already successfully does. Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:55 +08:00
drop:
BT_ERR("%s unexpected SMP command 0x%02x from %pMR", hcon->hdev->name,
code, &hcon->dst);
kfree_skb(skb);
return 0;
}
static void smp_teardown_cb(struct l2cap_chan *chan, int err)
{
struct l2cap_conn *conn = chan->conn;
BT_DBG("chan %p", chan);
Bluetooth: Fix locking of the SMP context Before the move the l2cap_chan the SMP context (smp_chan) didn't have any kind of proper locking. The best there existed was the HCI_CONN_LE_SMP_PEND flag which was used to enable mutual exclusion for potential multiple creators of the SMP context. Now that SMP has been converted to use the l2cap_chan infrastructure and since the SMP context is directly mapped to a corresponding l2cap_chan we get the SMP context locking essentially for free through the l2cap_chan lock. For all callbacks that l2cap_core.c makes for each channel implementation (smp.c in the case of SMP) the l2cap_chan lock is held through l2cap_chan_lock(chan). Since the calls from l2cap_core.c to smp.c are covered the only missing piece to have the locking implemented properly is to ensure that the lock is held for any other call path that may access the SMP context. This means user responses through mgmt.c, requests to elevate the security of a connection through hci_conn.c, as well as any deferred work through workqueues. This patch adds the necessary locking to all these other code paths that try to access the SMP context. Since mutual exclusion for the l2cap_chan access is now covered from all directions the patch also removes unnecessary HCI_CONN_LE_SMP_PEND flag (once we've acquired the chan lock we can simply check whether chan->smp is set to know if there's an SMP context). Signed-off-by: Johan Hedberg <johan.hedberg@intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
2014-09-06 03:19:52 +08:00
if (chan->data)
smp_chan_destroy(conn);
conn->smp = NULL;
l2cap_chan_put(chan);
}
static void bredr_pairing(struct l2cap_chan *chan)
{
struct l2cap_conn *conn = chan->conn;
struct hci_conn *hcon = conn->hcon;
struct hci_dev *hdev = hcon->hdev;
struct smp_cmd_pairing req;
struct smp_chan *smp;
BT_DBG("chan %p", chan);
/* Only new pairings are interesting */
if (!test_bit(HCI_CONN_NEW_LINK_KEY, &hcon->flags))
return;
/* Don't bother if we're not encrypted */
if (!test_bit(HCI_CONN_ENCRYPT, &hcon->flags))
return;
/* Only master may initiate SMP over BR/EDR */
if (hcon->role != HCI_ROLE_MASTER)
return;
/* Secure Connections support must be enabled */
if (!test_bit(HCI_SC_ENABLED, &hdev->dev_flags))
return;
/* BR/EDR must use Secure Connections for SMP */
if (!test_bit(HCI_CONN_AES_CCM, &hcon->flags) &&
!test_bit(HCI_FORCE_LESC, &hdev->dbg_flags))
return;
/* If our LE support is not enabled don't do anything */
if (!test_bit(HCI_LE_ENABLED, &hdev->dev_flags))
return;
/* Don't bother if remote LE support is not enabled */
if (!lmp_host_le_capable(hcon))
return;
/* Remote must support SMP fixed chan for BR/EDR */
if (!(conn->remote_fixed_chan & L2CAP_FC_SMP_BREDR))
return;
/* Don't bother if SMP is already ongoing */
if (chan->data)
return;
smp = smp_chan_create(conn);
if (!smp) {
BT_ERR("%s unable to create SMP context for BR/EDR",
hdev->name);
return;
}
set_bit(SMP_FLAG_SC, &smp->flags);
BT_DBG("%s starting SMP over BR/EDR", hdev->name);
/* Prepare and send the BR/EDR SMP Pairing Request */
build_bredr_pairing_cmd(smp, &req, NULL);
smp->preq[0] = SMP_CMD_PAIRING_REQ;
memcpy(&smp->preq[1], &req, sizeof(req));
smp_send_cmd(conn, SMP_CMD_PAIRING_REQ, sizeof(req), &req);
SMP_ALLOW_CMD(smp, SMP_CMD_PAIRING_RSP);
}
static void smp_resume_cb(struct l2cap_chan *chan)
{
struct smp_chan *smp = chan->data;
struct l2cap_conn *conn = chan->conn;
struct hci_conn *hcon = conn->hcon;
BT_DBG("chan %p", chan);
if (hcon->type == ACL_LINK) {
bredr_pairing(chan);
return;
}
if (!smp)
return;
if (!test_bit(HCI_CONN_ENCRYPT, &hcon->flags))
return;
cancel_delayed_work(&smp->security_timer);
smp_distribute_keys(smp);
}
static void smp_ready_cb(struct l2cap_chan *chan)
{
struct l2cap_conn *conn = chan->conn;
struct hci_conn *hcon = conn->hcon;
BT_DBG("chan %p", chan);
conn->smp = chan;
l2cap_chan_hold(chan);
if (hcon->type == ACL_LINK && test_bit(HCI_CONN_ENCRYPT, &hcon->flags))
bredr_pairing(chan);
}
static int smp_recv_cb(struct l2cap_chan *chan, struct sk_buff *skb)
{
int err;
BT_DBG("chan %p", chan);
err = smp_sig_channel(chan, skb);
if (err) {
struct smp_chan *smp = chan->data;
if (smp)
cancel_delayed_work_sync(&smp->security_timer);
hci_disconnect(chan->conn->hcon, HCI_ERROR_AUTH_FAILURE);
}
return err;
}
static struct sk_buff *smp_alloc_skb_cb(struct l2cap_chan *chan,
unsigned long hdr_len,
unsigned long len, int nb)
{
struct sk_buff *skb;
skb = bt_skb_alloc(hdr_len + len, GFP_KERNEL);
if (!skb)
return ERR_PTR(-ENOMEM);
skb->priority = HCI_PRIO_MAX;
bt_cb(skb)->chan = chan;
return skb;
}
static const struct l2cap_ops smp_chan_ops = {
.name = "Security Manager",
.ready = smp_ready_cb,
.recv = smp_recv_cb,
.alloc_skb = smp_alloc_skb_cb,
.teardown = smp_teardown_cb,
.resume = smp_resume_cb,
.new_connection = l2cap_chan_no_new_connection,
.state_change = l2cap_chan_no_state_change,
.close = l2cap_chan_no_close,
.defer = l2cap_chan_no_defer,
.suspend = l2cap_chan_no_suspend,
.set_shutdown = l2cap_chan_no_set_shutdown,
.get_sndtimeo = l2cap_chan_no_get_sndtimeo,
.memcpy_fromiovec = l2cap_chan_no_memcpy_fromiovec,
};
static inline struct l2cap_chan *smp_new_conn_cb(struct l2cap_chan *pchan)
{
struct l2cap_chan *chan;
BT_DBG("pchan %p", pchan);
chan = l2cap_chan_create();
if (!chan)
return NULL;
chan->chan_type = pchan->chan_type;
chan->ops = &smp_chan_ops;
chan->scid = pchan->scid;
chan->dcid = chan->scid;
chan->imtu = pchan->imtu;
chan->omtu = pchan->omtu;
chan->mode = pchan->mode;
/* Other L2CAP channels may request SMP routines in order to
* change the security level. This means that the SMP channel
* lock must be considered in its own category to avoid lockdep
* warnings.
*/
atomic_set(&chan->nesting, L2CAP_NESTING_SMP);
BT_DBG("created chan %p", chan);
return chan;
}
static const struct l2cap_ops smp_root_chan_ops = {
.name = "Security Manager Root",
.new_connection = smp_new_conn_cb,
/* None of these are implemented for the root channel */
.close = l2cap_chan_no_close,
.alloc_skb = l2cap_chan_no_alloc_skb,
.recv = l2cap_chan_no_recv,
.state_change = l2cap_chan_no_state_change,
.teardown = l2cap_chan_no_teardown,
.ready = l2cap_chan_no_ready,
.defer = l2cap_chan_no_defer,
.suspend = l2cap_chan_no_suspend,
.resume = l2cap_chan_no_resume,
.set_shutdown = l2cap_chan_no_set_shutdown,
.get_sndtimeo = l2cap_chan_no_get_sndtimeo,
.memcpy_fromiovec = l2cap_chan_no_memcpy_fromiovec,
};
static struct l2cap_chan *smp_add_cid(struct hci_dev *hdev, u16 cid)
{
struct l2cap_chan *chan;
struct crypto_blkcipher *tfm_aes;
if (cid == L2CAP_CID_SMP_BREDR) {
tfm_aes = NULL;
goto create_chan;
}
tfm_aes = crypto_alloc_blkcipher("ecb(aes)", 0, 0);
if (IS_ERR(tfm_aes)) {
BT_ERR("Unable to create crypto context");
return ERR_PTR(PTR_ERR(tfm_aes));
}
create_chan:
chan = l2cap_chan_create();
if (!chan) {
crypto_free_blkcipher(tfm_aes);
return ERR_PTR(-ENOMEM);
}
chan->data = tfm_aes;
l2cap_add_scid(chan, cid);
l2cap_chan_set_defaults(chan);
bacpy(&chan->src, &hdev->bdaddr);
if (cid == L2CAP_CID_SMP)
chan->src_type = BDADDR_LE_PUBLIC;
else
chan->src_type = BDADDR_BREDR;
chan->state = BT_LISTEN;
chan->mode = L2CAP_MODE_BASIC;
chan->imtu = L2CAP_DEFAULT_MTU;
chan->ops = &smp_root_chan_ops;
/* Set correct nesting level for a parent/listening channel */
atomic_set(&chan->nesting, L2CAP_NESTING_PARENT);
return chan;
}
static void smp_del_chan(struct l2cap_chan *chan)
{
struct crypto_blkcipher *tfm_aes;
BT_DBG("chan %p", chan);
tfm_aes = chan->data;
if (tfm_aes) {
chan->data = NULL;
crypto_free_blkcipher(tfm_aes);
}
l2cap_chan_put(chan);
}
int smp_register(struct hci_dev *hdev)
{
struct l2cap_chan *chan;
BT_DBG("%s", hdev->name);
chan = smp_add_cid(hdev, L2CAP_CID_SMP);
if (IS_ERR(chan))
return PTR_ERR(chan);
hdev->smp_data = chan;
if (!lmp_sc_capable(hdev) &&
!test_bit(HCI_FORCE_LESC, &hdev->dbg_flags))
return 0;
chan = smp_add_cid(hdev, L2CAP_CID_SMP_BREDR);
if (IS_ERR(chan)) {
int err = PTR_ERR(chan);
chan = hdev->smp_data;
hdev->smp_data = NULL;
smp_del_chan(chan);
return err;
}
hdev->smp_bredr_data = chan;
return 0;
}
void smp_unregister(struct hci_dev *hdev)
{
struct l2cap_chan *chan;
if (hdev->smp_bredr_data) {
chan = hdev->smp_bredr_data;
hdev->smp_bredr_data = NULL;
smp_del_chan(chan);
}
if (hdev->smp_data) {
chan = hdev->smp_data;
hdev->smp_data = NULL;
smp_del_chan(chan);
}
}