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- markus@cvs.openbsd.org 2001/04/03 23:32:12

Browse Source 
[kex.c kex.h packet.c sshconnect2.c sshd.c]
     undo parts of recent my changes: main part of keyexchange does not
     need dispatch-callbacks, since application data is delayed until
     the keyexchange completes (if i understand the drafts correctly).
     add some infrastructure for re-keying.
This commit is contained in:
Ben Lindstrom 2001-04-04 02:00:54 +00:00
parent 9323d96479
commit 2d90e00309
6 changed files with 156 additions and 130 deletions
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8
ChangeLog
View File

@ -13,6 +13,12 @@
- todd@cvs.openbsd.org 2001/04/03 21:19:38
[ssh_config]
id_rsa1/2 -> id_rsa; ok markus@
- markus@cvs.openbsd.org 2001/04/03 23:32:12
[kex.c kex.h packet.c sshconnect2.c sshd.c]
undo parts of recent my changes: main part of keyexchange does not
need dispatch-callbacks, since application data is delayed until
the keyexchange completes (if i understand the drafts correctly).
add some infrastructure for re-keying.
20010403
- OpenBSD CVS Sync
@ -4823,4 +4829,4 @@
- Wrote replacements for strlcpy and mkdtemp
- Released 1.0pre1
$Id: ChangeLog,v 1.1051 2001/04/04 01:58:48 mouring Exp $
$Id: ChangeLog,v 1.1052 2001/04/04 02:00:54 mouring Exp $

85
kex.c
View File

@ -23,7 +23,7 @@
*/
#include "includes.h"
RCSID("$OpenBSD: kex.c,v 1.26 2001/04/03 19:53:29 markus Exp $");
RCSID("$OpenBSD: kex.c,v 1.27 2001/04/03 23:32:11 markus Exp $");
#include <openssl/crypto.h>
@ -131,7 +131,7 @@ kex_input_newkeys(int type, int plen, void *ctxt)
for (i = 30; i <= 49; i++)
dispatch_set(i, &kex_protocol_error);
buffer_clear(&kex->peer);
buffer_clear(&kex->my);
/* buffer_clear(&kex->my); */
kex->flags &= ~KEX_INIT_SENT;
}
@ -152,7 +152,6 @@ kex_input_kexinit(int type, int plen, void *ctxt)
int dlen;
Kex *kex = (Kex *)ctxt;
dispatch_set(SSH2_MSG_KEXINIT, &kex_protocol_error);
debug("SSH2_MSG_KEXINIT received");
ptr = packet_get_raw(&dlen);
@ -274,18 +273,20 @@ choose_hostkeyalg(Kex *k, char *client, char *server)
}
void
kex_choose_conf(Kex *k)
kex_choose_conf(Kex *kex)
{
Newkeys *newkeys;
char **my, **peer;
char **cprop, **sprop;
int nenc, nmac, ncomp;
int mode;
int ctos; /* direction: if true client-to-server */
int need;
my = kex_buf2prop(&k->my);
peer = kex_buf2prop(&k->peer);
my = kex_buf2prop(&kex->my);
peer = kex_buf2prop(&kex->peer);
if (k->server) {
if (kex->server) {
cprop=peer;
sprop=my;
} else {
@ -294,42 +295,44 @@ kex_choose_conf(Kex *k)
}
for (mode = 0; mode < MODE_MAX; mode++) {
int nenc, nmac, ncomp;
ctos = (!k->server && mode == MODE_OUT) || (k->server && mode == MODE_IN);
newkeys = xmalloc(sizeof(*newkeys));
memset(newkeys, 0, sizeof(*newkeys));
kex->keys[mode] = newkeys;
ctos = (!kex->server && mode == MODE_OUT) || (kex->server && mode == MODE_IN);
nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
choose_enc (&k->enc [mode], cprop[nenc], sprop[nenc]);
choose_mac (&k->mac [mode], cprop[nmac], sprop[nmac]);
choose_comp(&k->comp[mode], cprop[ncomp], sprop[ncomp]);
choose_enc (&newkeys->enc, cprop[nenc], sprop[nenc]);
choose_mac (&newkeys->mac, cprop[nmac], sprop[nmac]);
choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]);
debug("kex: %s %s %s %s",
ctos ? "client->server" : "server->client",
k->enc[mode].name,
k->mac[mode].name,
k->comp[mode].name);
newkeys->enc.name,
newkeys->mac.name,
newkeys->comp.name);
}
choose_kex(k, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
choose_hostkeyalg(k, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
need = 0;
for (mode = 0; mode < MODE_MAX; mode++) {
if (need < k->enc[mode].cipher->key_len)
need = k->enc[mode].cipher->key_len;
if (need < k->enc[mode].cipher->block_size)
need = k->enc[mode].cipher->block_size;
if (need < k->mac[mode].key_len)
need = k->mac[mode].key_len;
newkeys = kex->keys[mode];
if (need < newkeys->enc.cipher->key_len)
need = newkeys->enc.cipher->key_len;
if (need < newkeys->enc.cipher->block_size)
need = newkeys->enc.cipher->block_size;
if (need < newkeys->mac.key_len)
need = newkeys->mac.key_len;
}
/* XXX need runden? */
k->we_need = need;
kex->we_need = need;
kex_prop_free(my);
kex_prop_free(peer);
}
u_char *
derive_key(int id, int need, u_char *hash, BIGNUM *shared_secret)
derive_key(Kex *kex, int id, int need, u_char *hash, BIGNUM *shared_secret)
{
Buffer b;
EVP_MD *evp_md = EVP_sha1();
@ -346,7 +349,7 @@ derive_key(int id, int need, u_char *hash, BIGNUM *shared_secret)
EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); /* shared_secret K */
EVP_DigestUpdate(&md, hash, mdsz); /* transport-06 */
EVP_DigestUpdate(&md, &c, 1); /* key id */
EVP_DigestUpdate(&md, hash, mdsz); /* session id */
EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
EVP_DigestFinal(&md, digest, NULL);
/* expand */
@ -365,26 +368,36 @@ derive_key(int id, int need, u_char *hash, BIGNUM *shared_secret)
return digest;
}
Newkeys *x_newkeys[MODE_MAX];
#define NKEYS 6
void
kex_derive_keys(Kex *k, u_char *hash, BIGNUM *shared_secret)
kex_derive_keys(Kex *kex, u_char *hash, BIGNUM *shared_secret)
{
int i;
int mode;
int ctos;
Newkeys *newkeys;
u_char *keys[NKEYS];
int i, mode, ctos;
for (i = 0; i < NKEYS; i++)
keys[i] = derive_key('A'+i, k->we_need, hash, shared_secret);
keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, shared_secret);
debug("kex_derive_keys");
for (mode = 0; mode < MODE_MAX; mode++) {
ctos = (!k->server && mode == MODE_OUT) || (k->server && mode == MODE_IN);
k->enc[mode].iv = keys[ctos ? 0 : 1];
k->enc[mode].key = keys[ctos ? 2 : 3];
k->mac[mode].key = keys[ctos ? 4 : 5];
newkeys = kex->keys[mode];
ctos = (!kex->server && mode == MODE_OUT) || (kex->server && mode == MODE_IN);
newkeys->enc.iv = keys[ctos ? 0 : 1];
newkeys->enc.key = keys[ctos ? 2 : 3];
newkeys->mac.key = keys[ctos ? 4 : 5];
x_newkeys[mode] = newkeys;
}
}
Newkeys *
kex_get_newkeys(int mode)
{
return x_newkeys[mode];
}
#if defined(DEBUG_KEX) || defined(DEBUG_KEXDH)
void
dump_digest(char *msg, u_char *digest, int len)

75
kex.h
View File

@ -1,4 +1,4 @@
/* $OpenBSD: kex.h,v 1.18 2001/04/03 19:53:29 markus Exp $ */
/* $OpenBSD: kex.h,v 1.19 2001/04/03 23:32:12 markus Exp $ */
/*
* Copyright (c) 2000 Markus Friedl. All rights reserved.
@ -59,64 +59,69 @@ enum kex_exchange {
DH_GEX_SHA1
};
#define KEX_INIT_SENT 0x0001
typedef struct Kex Kex;
typedef struct Mac Mac;
typedef struct Comp Comp;
typedef struct Enc Enc;
typedef struct Newkeys Newkeys;
struct Enc {
char *name;
Cipher *cipher;
int enabled;
char *name;
Cipher *cipher;
int enabled;
u_char *key;
u_char *iv;
};
struct Mac {
char *name;
int enabled;
EVP_MD *md;
int mac_len;
char *name;
int enabled;
EVP_MD *md;
int mac_len;
u_char *key;
int key_len;
int key_len;
};
struct Comp {
int type;
int enabled;
char *name;
int type;
int enabled;
char *name;
};
struct Newkeys {
Enc enc;
Mac mac;
Comp comp;
};
#define KEX_INIT_SENT 0x0001
struct Kex {
Enc enc [MODE_MAX];
Mac mac [MODE_MAX];
Comp comp[MODE_MAX];
int we_need;
int server;
char *name;
int hostkey_type;
int kex_type;
/* used during kex */
Buffer my;
Buffer peer;
int newkeys;
int flags;
void *state;
char *client_version_string;
char *server_version_string;
int (*check_host_key)(Key *hostkey);
Key *(*load_host_key)(int type);
u_char *session_id;
int session_id_len;
Newkeys *keys[MODE_MAX];
int we_need;
int server;
char *name;
int hostkey_type;
int kex_type;
Buffer my;
Buffer peer;
int newkeys;
int flags;
char *client_version_string;
char *server_version_string;
int (*check_host_key)(Key *hostkey);
Key *(*load_host_key)(int type);
};
void kex_derive_keys(Kex *k, u_char *hash, BIGNUM *shared_secret);
void packet_set_kex(Kex *k);
Kex *kex_start(char *proposal[PROPOSAL_MAX]);
void kex_send_newkeys(void);
void kex_send_kexinit(Kex *kex);
void kex_protocol_error(int type, int plen, void *ctxt);
void kex_derive_keys(Kex *k, u_char *hash, BIGNUM *shared_secret);
void kexdh(Kex *);
void kexgex(Kex *);
Newkeys *kex_get_newkeys(int mode);
#if defined(DEBUG_KEX) || defined(DEBUG_KEXDH)
void dump_digest(char *msg, u_char *digest, int len);
#endif

108
packet.c
View File

@ -37,7 +37,7 @@
*/
#include "includes.h"
RCSID("$OpenBSD: packet.c,v 1.56 2001/03/03 21:41:07 millert Exp $");
RCSID("$OpenBSD: packet.c,v 1.57 2001/04/03 23:32:12 markus Exp $");
#include "xmalloc.h"
#include "buffer.h"
@ -121,20 +121,8 @@ static int interactive_mode = 0;
int use_ssh2_packet_format = 0;
/* Session key information for Encryption and MAC */
Kex *kex = NULL;
Newkeys *newkeys[MODE_MAX];
void
packet_set_kex(Kex *k)
{
if( k->mac[MODE_IN ].key == NULL ||
k->enc[MODE_IN ].key == NULL ||
k->enc[MODE_IN ].iv == NULL ||
k->mac[MODE_OUT].key == NULL ||
k->enc[MODE_OUT].key == NULL ||
k->enc[MODE_OUT].iv == NULL)
fatal("bad KEX");
kex = k;
}
void
clear_enc_keys(Enc *enc, int len)
{
@ -150,6 +138,7 @@ packet_set_ssh2_format(void)
{
DBG(debug("use_ssh2_packet_format"));
use_ssh2_packet_format = 1;
newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL;
}
/*
@ -522,6 +511,41 @@ packet_send1(void)
*/
}
void
set_newkeys(int mode)
{
Enc *enc;
Mac *mac;
Comp *comp;
CipherContext *cc;
debug("newkeys: mode %d", mode);
cc = (mode == MODE_OUT) ? &send_context : &receive_context;
if (newkeys[mode] != NULL) {
debug("newkeys: rekeying");
memset(cc, 0, sizeof(*cc));
// free old keys, reset compression cipher-contexts;
}
newkeys[mode] = kex_get_newkeys(mode);
if (newkeys[mode] == NULL)
fatal("newkeys: no keys for mode %d", mode);
enc = &newkeys[mode]->enc;
mac = &newkeys[mode]->mac;
comp = &newkeys[mode]->comp;
if (mac->md != NULL)
mac->enabled = 1;
DBG(debug("cipher_init_context: %d", mode));
cipher_init(cc, enc->cipher, enc->key, enc->cipher->key_len,
enc->iv, enc->cipher->block_size);
clear_enc_keys(enc, enc->cipher->key_len);
if (comp->type != 0 && comp->enabled == 0) {
comp->enabled = 1;
if (! packet_compression)
packet_start_compression(6);
}
}
/*
* Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
*/
@ -540,10 +564,10 @@ packet_send2(void)
Comp *comp = NULL;
int block_size;
if (kex != NULL) {
enc = &kex->enc[MODE_OUT];
mac = &kex->mac[MODE_OUT];
comp = &kex->comp[MODE_OUT];
if (newkeys[MODE_OUT] != NULL) {
enc = &newkeys[MODE_OUT]->enc;
mac = &newkeys[MODE_OUT]->mac;
comp = &newkeys[MODE_OUT]->comp;
}
block_size = enc ? enc->cipher->block_size : 8;
@ -622,22 +646,8 @@ packet_send2(void)
log("outgoing seqnr wraps around");
buffer_clear(&outgoing_packet);
if (type == SSH2_MSG_NEWKEYS) {
if (kex==NULL || mac==NULL || enc==NULL || comp==NULL)
fatal("packet_send2: no KEX");
if (mac->md != NULL)
mac->enabled = 1;
DBG(debug("cipher_init send_context"));
cipher_init(&send_context, enc->cipher,
enc->key, enc->cipher->key_len,
enc->iv, enc->cipher->block_size);
clear_enc_keys(enc, kex->we_need);
if (comp->type != 0 && comp->enabled == 0) {
comp->enabled = 1;
if (! packet_compression)
packet_start_compression(6);
}
}
if (type == SSH2_MSG_NEWKEYS)
set_newkeys(MODE_OUT);
}
void
@ -833,10 +843,10 @@ packet_read_poll2(int *payload_len_ptr)
Mac *mac = NULL;
Comp *comp = NULL;
if (kex != NULL) {
enc = &kex->enc[MODE_IN];
mac = &kex->mac[MODE_IN];
comp = &kex->comp[MODE_IN];
if (newkeys[MODE_IN] != NULL) {
enc = &newkeys[MODE_IN]->enc;
mac = &newkeys[MODE_IN]->mac;
comp = &newkeys[MODE_IN]->comp;
}
maclen = mac && mac->enabled ? mac->mac_len : 0;
block_size = enc ? enc->cipher->block_size : 8;
@ -930,22 +940,8 @@ packet_read_poll2(int *payload_len_ptr)
/* extract packet type */
type = (u_char)buf[0];
if (type == SSH2_MSG_NEWKEYS) {
if (kex==NULL || mac==NULL || enc==NULL || comp==NULL)
fatal("packet_read_poll2: no KEX");
if (mac->md != NULL)
mac->enabled = 1;
DBG(debug("cipher_init receive_context"));
cipher_init(&receive_context, enc->cipher,
enc->key, enc->cipher->key_len,
enc->iv, enc->cipher->block_size);
clear_enc_keys(enc, kex->we_need);
if (comp->type != 0 && comp->enabled == 0) {
comp->enabled = 1;
if (! packet_compression)
packet_start_compression(6);
}
}
if (type == SSH2_MSG_NEWKEYS)
set_newkeys(MODE_IN);
#ifdef PACKET_DEBUG
fprintf(stderr, "read/plain[%d]:\r\n", type);
@ -1339,8 +1335,8 @@ packet_inject_ignore(int sumlen)
have = buffer_len(&outgoing_packet);
debug2("packet_inject_ignore: current %d", have);
if (kex != NULL)
enc = &kex->enc[MODE_OUT];
if (newkeys[MODE_OUT] != NULL)
enc = &newkeys[MODE_OUT]->enc;
blocksize = enc ? enc->cipher->block_size : 8;
padlen = blocksize - (have % blocksize);
if (padlen < 4)

5
sshconnect2.c
View File

@ -23,7 +23,7 @@
*/
#include "includes.h"
RCSID("$OpenBSD: sshconnect2.c,v 1.61 2001/04/03 19:53:29 markus Exp $");
RCSID("$OpenBSD: sshconnect2.c,v 1.62 2001/04/03 23:32:12 markus Exp $");
#include <openssl/bn.h>
#include <openssl/md5.h>
@ -117,6 +117,9 @@ ssh_kex2(char *host, struct sockaddr *hostaddr)
/* start key exchange */
dispatch_run(DISPATCH_BLOCK, &kex->newkeys, kex);
session_id2 = kex->session_id;
session_id2_len = kex->session_id_len;
#ifdef DEBUG_KEXDH
/* send 1st encrypted/maced/compressed message */
packet_start(SSH2_MSG_IGNORE);

5
sshd.c
View File

@ -40,7 +40,7 @@
*/
#include "includes.h"
RCSID("$OpenBSD: sshd.c,v 1.186 2001/04/03 19:53:29 markus Exp $");
RCSID("$OpenBSD: sshd.c,v 1.187 2001/04/03 23:32:12 markus Exp $");
#include <openssl/dh.h>
#include <openssl/bn.h>
@ -1434,6 +1434,9 @@ do_ssh2_kex(void)
/* start key exchange */
dispatch_run(DISPATCH_BLOCK, &kex->newkeys, kex);
session_id2 = kex->session_id;
session_id2_len = kex->session_id_len;
#ifdef DEBUG_KEXDH
/* send 1st encrypted/maced/compressed message */
packet_start(SSH2_MSG_IGNORE);