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linux/net/mac80211/tkip.c
Jouni Malinen 6f60126521 mac80211: Fix TKIP replay protection immediately after key setup 
TKIP replay protection was skipped for the very first frame received
after a new key is configured. While this is potentially needed to avoid
dropping a frame in some cases, this does leave a window for replay
attacks with group-addressed frames at the station side. Any earlier
frame sent by the AP using the same key would be accepted as a valid
frame and the internal RSC would then be updated to the TSC from that
frame. This would allow multiple previously transmitted group-addressed
frames to be replayed until the next valid new group-addressed frame
from the AP is received by the station.

Fix this by limiting the no-replay-protection exception to apply only
for the case where TSC=0, i.e., when this is for the very first frame
protected using the new key, and the local RSC had not been set to a
higher value when configuring the key (which may happen with GTK).

Signed-off-by: Jouni Malinen <j@w1.fi>
Link: https://lore.kernel.org/r/20200107153545.10934-1-j@w1.fi
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2020-01-15 09:52:12 +01:00

324 lines
11 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright 2002-2004, Instant802 Networks, Inc.
* Copyright 2005, Devicescape Software, Inc.
* Copyright (C) 2016 Intel Deutschland GmbH
*/
#include <linux/kernel.h>
#include <linux/bitops.h>
#include <linux/types.h>
#include <linux/netdevice.h>
#include <linux/export.h>
#include <asm/unaligned.h>
#include <net/mac80211.h>
#include "driver-ops.h"
#include "key.h"
#include "tkip.h"
#include "wep.h"
#define PHASE1_LOOP_COUNT 8
/*
* 2-byte by 2-byte subset of the full AES S-box table; second part of this
* table is identical to first part but byte-swapped
*/
static const u16 tkip_sbox[256] =
{
0xC6A5, 0xF884, 0xEE99, 0xF68D, 0xFF0D, 0xD6BD, 0xDEB1, 0x9154,
0x6050, 0x0203, 0xCEA9, 0x567D, 0xE719, 0xB562, 0x4DE6, 0xEC9A,
0x8F45, 0x1F9D, 0x8940, 0xFA87, 0xEF15, 0xB2EB, 0x8EC9, 0xFB0B,
0x41EC, 0xB367, 0x5FFD, 0x45EA, 0x23BF, 0x53F7, 0xE496, 0x9B5B,
0x75C2, 0xE11C, 0x3DAE, 0x4C6A, 0x6C5A, 0x7E41, 0xF502, 0x834F,
0x685C, 0x51F4, 0xD134, 0xF908, 0xE293, 0xAB73, 0x6253, 0x2A3F,
0x080C, 0x9552, 0x4665, 0x9D5E, 0x3028, 0x37A1, 0x0A0F, 0x2FB5,
0x0E09, 0x2436, 0x1B9B, 0xDF3D, 0xCD26, 0x4E69, 0x7FCD, 0xEA9F,
0x121B, 0x1D9E, 0x5874, 0x342E, 0x362D, 0xDCB2, 0xB4EE, 0x5BFB,
0xA4F6, 0x764D, 0xB761, 0x7DCE, 0x527B, 0xDD3E, 0x5E71, 0x1397,
0xA6F5, 0xB968, 0x0000, 0xC12C, 0x4060, 0xE31F, 0x79C8, 0xB6ED,
0xD4BE, 0x8D46, 0x67D9, 0x724B, 0x94DE, 0x98D4, 0xB0E8, 0x854A,
0xBB6B, 0xC52A, 0x4FE5, 0xED16, 0x86C5, 0x9AD7, 0x6655, 0x1194,
0x8ACF, 0xE910, 0x0406, 0xFE81, 0xA0F0, 0x7844, 0x25BA, 0x4BE3,
0xA2F3, 0x5DFE, 0x80C0, 0x058A, 0x3FAD, 0x21BC, 0x7048, 0xF104,
0x63DF, 0x77C1, 0xAF75, 0x4263, 0x2030, 0xE51A, 0xFD0E, 0xBF6D,
0x814C, 0x1814, 0x2635, 0xC32F, 0xBEE1, 0x35A2, 0x88CC, 0x2E39,
0x9357, 0x55F2, 0xFC82, 0x7A47, 0xC8AC, 0xBAE7, 0x322B, 0xE695,
0xC0A0, 0x1998, 0x9ED1, 0xA37F, 0x4466, 0x547E, 0x3BAB, 0x0B83,
0x8CCA, 0xC729, 0x6BD3, 0x283C, 0xA779, 0xBCE2, 0x161D, 0xAD76,
0xDB3B, 0x6456, 0x744E, 0x141E, 0x92DB, 0x0C0A, 0x486C, 0xB8E4,
0x9F5D, 0xBD6E, 0x43EF, 0xC4A6, 0x39A8, 0x31A4, 0xD337, 0xF28B,
0xD532, 0x8B43, 0x6E59, 0xDAB7, 0x018C, 0xB164, 0x9CD2, 0x49E0,
0xD8B4, 0xACFA, 0xF307, 0xCF25, 0xCAAF, 0xF48E, 0x47E9, 0x1018,
0x6FD5, 0xF088, 0x4A6F, 0x5C72, 0x3824, 0x57F1, 0x73C7, 0x9751,
0xCB23, 0xA17C, 0xE89C, 0x3E21, 0x96DD, 0x61DC, 0x0D86, 0x0F85,
0xE090, 0x7C42, 0x71C4, 0xCCAA, 0x90D8, 0x0605, 0xF701, 0x1C12,
0xC2A3, 0x6A5F, 0xAEF9, 0x69D0, 0x1791, 0x9958, 0x3A27, 0x27B9,
0xD938, 0xEB13, 0x2BB3, 0x2233, 0xD2BB, 0xA970, 0x0789, 0x33A7,
0x2DB6, 0x3C22, 0x1592, 0xC920, 0x8749, 0xAAFF, 0x5078, 0xA57A,
0x038F, 0x59F8, 0x0980, 0x1A17, 0x65DA, 0xD731, 0x84C6, 0xD0B8,
0x82C3, 0x29B0, 0x5A77, 0x1E11, 0x7BCB, 0xA8FC, 0x6DD6, 0x2C3A,
};
static u16 tkipS(u16 val)
{
return tkip_sbox[val & 0xff] ^ swab16(tkip_sbox[val >> 8]);
}
static u8 *write_tkip_iv(u8 *pos, u16 iv16)
{
*pos++ = iv16 >> 8;
*pos++ = ((iv16 >> 8) | 0x20) & 0x7f;
*pos++ = iv16 & 0xFF;
return pos;
}
/*
* P1K := Phase1(TA, TK, TSC)
* TA = transmitter address (48 bits)
* TK = dot11DefaultKeyValue or dot11KeyMappingValue (128 bits)
* TSC = TKIP sequence counter (48 bits, only 32 msb bits used)
* P1K: 80 bits
*/
static void tkip_mixing_phase1(const u8 *tk, struct tkip_ctx *ctx,
const u8 *ta, u32 tsc_IV32)
{
int i, j;
u16 *p1k = ctx->p1k;
p1k[0] = tsc_IV32 & 0xFFFF;
p1k[1] = tsc_IV32 >> 16;
p1k[2] = get_unaligned_le16(ta + 0);
p1k[3] = get_unaligned_le16(ta + 2);
p1k[4] = get_unaligned_le16(ta + 4);
for (i = 0; i < PHASE1_LOOP_COUNT; i++) {
j = 2 * (i & 1);
p1k[0] += tkipS(p1k[4] ^ get_unaligned_le16(tk + 0 + j));
p1k[1] += tkipS(p1k[0] ^ get_unaligned_le16(tk + 4 + j));
p1k[2] += tkipS(p1k[1] ^ get_unaligned_le16(tk + 8 + j));
p1k[3] += tkipS(p1k[2] ^ get_unaligned_le16(tk + 12 + j));
p1k[4] += tkipS(p1k[3] ^ get_unaligned_le16(tk + 0 + j)) + i;
}
ctx->state = TKIP_STATE_PHASE1_DONE;
ctx->p1k_iv32 = tsc_IV32;
}
static void tkip_mixing_phase2(const u8 *tk, struct tkip_ctx *ctx,
u16 tsc_IV16, u8 *rc4key)
{
u16 ppk[6];
const u16 *p1k = ctx->p1k;
int i;
ppk[0] = p1k[0];
ppk[1] = p1k[1];
ppk[2] = p1k[2];
ppk[3] = p1k[3];
ppk[4] = p1k[4];
ppk[5] = p1k[4] + tsc_IV16;
ppk[0] += tkipS(ppk[5] ^ get_unaligned_le16(tk + 0));
ppk[1] += tkipS(ppk[0] ^ get_unaligned_le16(tk + 2));
ppk[2] += tkipS(ppk[1] ^ get_unaligned_le16(tk + 4));
ppk[3] += tkipS(ppk[2] ^ get_unaligned_le16(tk + 6));
ppk[4] += tkipS(ppk[3] ^ get_unaligned_le16(tk + 8));
ppk[5] += tkipS(ppk[4] ^ get_unaligned_le16(tk + 10));
ppk[0] += ror16(ppk[5] ^ get_unaligned_le16(tk + 12), 1);
ppk[1] += ror16(ppk[0] ^ get_unaligned_le16(tk + 14), 1);
ppk[2] += ror16(ppk[1], 1);
ppk[3] += ror16(ppk[2], 1);
ppk[4] += ror16(ppk[3], 1);
ppk[5] += ror16(ppk[4], 1);
rc4key = write_tkip_iv(rc4key, tsc_IV16);
*rc4key++ = ((ppk[5] ^ get_unaligned_le16(tk)) >> 1) & 0xFF;
for (i = 0; i < 6; i++)
put_unaligned_le16(ppk[i], rc4key + 2 * i);
}
/* Add TKIP IV and Ext. IV at @pos. @iv0, @iv1, and @iv2 are the first octets
* of the IV. Returns pointer to the octet following IVs (i.e., beginning of
* the packet payload). */
u8 *ieee80211_tkip_add_iv(u8 *pos, struct ieee80211_key_conf *keyconf, u64 pn)
{
pos = write_tkip_iv(pos, TKIP_PN_TO_IV16(pn));
*pos++ = (keyconf->keyidx << 6) | (1 << 5) /* Ext IV */;
put_unaligned_le32(TKIP_PN_TO_IV32(pn), pos);
return pos + 4;
}
EXPORT_SYMBOL_GPL(ieee80211_tkip_add_iv);
static void ieee80211_compute_tkip_p1k(struct ieee80211_key *key, u32 iv32)
{
struct ieee80211_sub_if_data *sdata = key->sdata;
struct tkip_ctx *ctx = &key->u.tkip.tx;
const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
lockdep_assert_held(&key->u.tkip.txlock);
/*
* Update the P1K when the IV32 is different from the value it
* had when we last computed it (or when not initialised yet).
* This might flip-flop back and forth if packets are processed
* out-of-order due to the different ACs, but then we have to
* just compute the P1K more often.
*/
if (ctx->p1k_iv32 != iv32 || ctx->state == TKIP_STATE_NOT_INIT)
tkip_mixing_phase1(tk, ctx, sdata->vif.addr, iv32);
}
void ieee80211_get_tkip_p1k_iv(struct ieee80211_key_conf *keyconf,
u32 iv32, u16 *p1k)
{
struct ieee80211_key *key = (struct ieee80211_key *)
container_of(keyconf, struct ieee80211_key, conf);
struct tkip_ctx *ctx = &key->u.tkip.tx;
spin_lock_bh(&key->u.tkip.txlock);
ieee80211_compute_tkip_p1k(key, iv32);
memcpy(p1k, ctx->p1k, sizeof(ctx->p1k));
spin_unlock_bh(&key->u.tkip.txlock);
}
EXPORT_SYMBOL(ieee80211_get_tkip_p1k_iv);
void ieee80211_get_tkip_rx_p1k(struct ieee80211_key_conf *keyconf,
const u8 *ta, u32 iv32, u16 *p1k)
{
const u8 *tk = &keyconf->key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
struct tkip_ctx ctx;
tkip_mixing_phase1(tk, &ctx, ta, iv32);
memcpy(p1k, ctx.p1k, sizeof(ctx.p1k));
}
EXPORT_SYMBOL(ieee80211_get_tkip_rx_p1k);
void ieee80211_get_tkip_p2k(struct ieee80211_key_conf *keyconf,
struct sk_buff *skb, u8 *p2k)
{
struct ieee80211_key *key = (struct ieee80211_key *)
container_of(keyconf, struct ieee80211_key, conf);
const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
struct tkip_ctx *ctx = &key->u.tkip.tx;
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
const u8 *data = (u8 *)hdr + ieee80211_hdrlen(hdr->frame_control);
u32 iv32 = get_unaligned_le32(&data[4]);
u16 iv16 = data[2] | (data[0] << 8);
spin_lock(&key->u.tkip.txlock);
ieee80211_compute_tkip_p1k(key, iv32);
tkip_mixing_phase2(tk, ctx, iv16, p2k);
spin_unlock(&key->u.tkip.txlock);
}
EXPORT_SYMBOL(ieee80211_get_tkip_p2k);
/*
* Encrypt packet payload with TKIP using @key. @pos is a pointer to the
* beginning of the buffer containing payload. This payload must include
* the IV/Ext.IV and space for (taildroom) four octets for ICV.
* @payload_len is the length of payload (_not_ including IV/ICV length).
* @ta is the transmitter addresses.
*/
int ieee80211_tkip_encrypt_data(struct arc4_ctx *ctx,
struct ieee80211_key *key,
struct sk_buff *skb,
u8 *payload, size_t payload_len)
{
u8 rc4key[16];
ieee80211_get_tkip_p2k(&key->conf, skb, rc4key);
return ieee80211_wep_encrypt_data(ctx, rc4key, 16,
payload, payload_len);
}
/* Decrypt packet payload with TKIP using @key. @pos is a pointer to the
* beginning of the buffer containing IEEE 802.11 header payload, i.e.,
* including IV, Ext. IV, real data, Michael MIC, ICV. @payload_len is the
* length of payload, including IV, Ext. IV, MIC, ICV. */
int ieee80211_tkip_decrypt_data(struct arc4_ctx *ctx,
struct ieee80211_key *key,
u8 *payload, size_t payload_len, u8 *ta,
u8 *ra, int only_iv, int queue,
u32 *out_iv32, u16 *out_iv16)
{
u32 iv32;
u32 iv16;
u8 rc4key[16], keyid, *pos = payload;
int res;
const u8 *tk = &key->conf.key[NL80211_TKIP_DATA_OFFSET_ENCR_KEY];
struct tkip_ctx_rx *rx_ctx = &key->u.tkip.rx[queue];
if (payload_len < 12)
return -1;
iv16 = (pos[0] << 8) | pos[2];
keyid = pos[3];
iv32 = get_unaligned_le32(pos + 4);
pos += 8;
if (!(keyid & (1 << 5)))
return TKIP_DECRYPT_NO_EXT_IV;
if ((keyid >> 6) != key->conf.keyidx)
return TKIP_DECRYPT_INVALID_KEYIDX;
/* Reject replays if the received TSC is smaller than or equal to the
* last received value in a valid message, but with an exception for
* the case where a new key has been set and no valid frame using that
* key has yet received and the local RSC was initialized to 0. This
* exception allows the very first frame sent by the transmitter to be
* accepted even if that transmitter were to use TSC 0 (IEEE 802.11
* described TSC to be initialized to 1 whenever a new key is taken into
* use).
*/
if (iv32 < rx_ctx->iv32 ||
(iv32 == rx_ctx->iv32 &&
(iv16 < rx_ctx->iv16 ||
(iv16 == rx_ctx->iv16 &&
(rx_ctx->iv32 || rx_ctx->iv16 ||
rx_ctx->ctx.state != TKIP_STATE_NOT_INIT)))))
return TKIP_DECRYPT_REPLAY;
if (only_iv) {
res = TKIP_DECRYPT_OK;
rx_ctx->ctx.state = TKIP_STATE_PHASE1_HW_UPLOADED;
goto done;
}
if (rx_ctx->ctx.state == TKIP_STATE_NOT_INIT ||
rx_ctx->iv32 != iv32) {
/* IV16 wrapped around - perform TKIP phase 1 */
tkip_mixing_phase1(tk, &rx_ctx->ctx, ta, iv32);
}
if (key->local->ops->update_tkip_key &&
key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE &&
rx_ctx->ctx.state != TKIP_STATE_PHASE1_HW_UPLOADED) {
struct ieee80211_sub_if_data *sdata = key->sdata;
if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
sdata = container_of(key->sdata->bss,
struct ieee80211_sub_if_data, u.ap);
drv_update_tkip_key(key->local, sdata, &key->conf, key->sta,
iv32, rx_ctx->ctx.p1k);
rx_ctx->ctx.state = TKIP_STATE_PHASE1_HW_UPLOADED;
}
tkip_mixing_phase2(tk, &rx_ctx->ctx, iv16, rc4key);
res = ieee80211_wep_decrypt_data(ctx, rc4key, 16, pos, payload_len - 12);
done:
if (res == TKIP_DECRYPT_OK) {
/*
* Record previously received IV, will be copied into the
* key information after MIC verification. It is possible
* that we don't catch replays of fragments but that's ok
* because the Michael MIC verication will then fail.
*/
*out_iv32 = iv32;
*out_iv16 = iv16;
}
return res;
}
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