*/
#include "includes.h"
-RCSID("$OpenBSD: kex.c,v 1.41 2001/12/28 15:06:00 markus Exp $");
+RCSID("$OpenBSD: kex.c,v 1.60 2004/06/21 17:36:31 avsm Exp $");
#include <openssl/crypto.h>
#include "mac.h"
#include "match.h"
#include "dispatch.h"
+#include "monitor.h"
#define KEX_COOKIE_LEN 16
static void
kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
{
- u_int32_t rand = 0;
int i;
buffer_clear(b);
- for (i = 0; i < KEX_COOKIE_LEN; i++) {
- if (i % 4 == 0)
- rand = arc4random();
- buffer_put_char(b, rand & 0xff);
- rand >>= 8;
- }
+ /*
+ * add a dummy cookie, the cookie will be overwritten by
+ * kex_send_kexinit(), each time a kexinit is set
+ */
+ for (i = 0; i < KEX_COOKIE_LEN; i++)
+ buffer_put_char(b, 0);
for (i = 0; i < PROPOSAL_MAX; i++)
buffer_put_cstring(b, proposal[i]);
buffer_put_char(b, 0); /* first_kex_packet_follows */
/* parse buffer and return algorithm proposal */
static char **
-kex_buf2prop(Buffer *raw)
+kex_buf2prop(Buffer *raw, int *first_kex_follows)
{
Buffer b;
int i;
}
/* first kex follows / reserved */
i = buffer_get_char(&b);
+ if (first_kex_follows != NULL)
+ *first_kex_follows = i;
debug2("kex_parse_kexinit: first_kex_follows %d ", i);
i = buffer_get_int(&b);
debug2("kex_parse_kexinit: reserved %d ", i);
}
static void
-kex_clear_dispatch(void)
+kex_reset_dispatch(void)
{
- int i;
-
- /* Numbers 30-49 are used for kex packets */
- for (i = 30; i <= 49; i++)
- dispatch_set(i, &kex_protocol_error);
+ dispatch_range(SSH2_MSG_TRANSPORT_MIN,
+ SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
+ dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
}
void
kex_finish(Kex *kex)
{
- kex_clear_dispatch();
+ kex_reset_dispatch();
packet_start(SSH2_MSG_NEWKEYS);
packet_send();
/* packet_write_wait(); */
debug("SSH2_MSG_NEWKEYS sent");
- debug("waiting for SSH2_MSG_NEWKEYS");
+ debug("expecting SSH2_MSG_NEWKEYS");
packet_read_expect(SSH2_MSG_NEWKEYS);
+ packet_check_eom();
debug("SSH2_MSG_NEWKEYS received");
kex->done = 1;
void
kex_send_kexinit(Kex *kex)
{
+ u_int32_t rnd = 0;
+ u_char *cookie;
+ int i;
+
if (kex == NULL) {
error("kex_send_kexinit: no kex, cannot rekey");
return;
return;
}
kex->done = 0;
+
+ /* generate a random cookie */
+ if (buffer_len(&kex->my) < KEX_COOKIE_LEN)
+ fatal("kex_send_kexinit: kex proposal too short");
+ cookie = buffer_ptr(&kex->my);
+ for (i = 0; i < KEX_COOKIE_LEN; i++) {
+ if (i % 4 == 0)
+ rnd = arc4random();
+ cookie[i] = rnd;
+ rnd >>= 8;
+ }
packet_start(SSH2_MSG_KEXINIT);
packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
packet_send();
packet_get_char();
for (i = 0; i < PROPOSAL_MAX; i++)
xfree(packet_get_string(NULL));
- packet_get_char();
- packet_get_int();
+ (void) packet_get_char();
+ (void) packet_get_int();
packet_check_eom();
kex_kexinit_finish(kex);
kex->done = 0;
kex_send_kexinit(kex); /* we start */
- kex_clear_dispatch();
- dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
+ kex_reset_dispatch();
return kex;
}
kex_choose_conf(kex);
- switch (kex->kex_type) {
- case DH_GRP1_SHA1:
- kexdh(kex);
- break;
- case DH_GEX_SHA1:
- kexgex(kex);
- break;
- default:
+ if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX &&
+ kex->kex[kex->kex_type] != NULL) {
+ (kex->kex[kex->kex_type])(kex);
+ } else {
fatal("Unsupported key exchange %d", kex->kex_type);
}
}
char *name = match_list(client, server, NULL);
if (name == NULL)
fatal("no matching cipher found: client %s server %s", client, server);
- enc->cipher = cipher_by_name(name);
- if (enc->cipher == NULL)
+ if ((enc->cipher = cipher_by_name(name)) == NULL)
fatal("matching cipher is not supported: %s", name);
enc->name = name;
enc->enabled = 0;
enc->iv = NULL;
enc->key = NULL;
+ enc->key_len = cipher_keylen(enc->cipher);
+ enc->block_size = cipher_blocksize(enc->cipher);
}
static void
choose_mac(Mac *mac, char *client, char *server)
if (k->name == NULL)
fatal("no kex alg");
if (strcmp(k->name, KEX_DH1) == 0) {
- k->kex_type = DH_GRP1_SHA1;
+ k->kex_type = KEX_DH_GRP1_SHA1;
+ } else if (strcmp(k->name, KEX_DH14) == 0) {
+ k->kex_type = KEX_DH_GRP14_SHA1;
} else if (strcmp(k->name, KEX_DHGEX) == 0) {
- k->kex_type = DH_GEX_SHA1;
+ k->kex_type = KEX_DH_GEX_SHA1;
} else
fatal("bad kex alg %s", k->name);
}
xfree(hostkeyalg);
}
+static int
+proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
+{
+ static int check[] = {
+ PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
+ };
+ int *idx;
+ char *p;
+
+ for (idx = &check[0]; *idx != -1; idx++) {
+ if ((p = strchr(my[*idx], ',')) != NULL)
+ *p = '\0';
+ if ((p = strchr(peer[*idx], ',')) != NULL)
+ *p = '\0';
+ if (strcmp(my[*idx], peer[*idx]) != 0) {
+ debug2("proposal mismatch: my %s peer %s",
+ my[*idx], peer[*idx]);
+ return (0);
+ }
+ }
+ debug2("proposals match");
+ return (1);
+}
+
static void
kex_choose_conf(Kex *kex)
{
int mode;
int ctos; /* direction: if true client-to-server */
int need;
+ int first_kex_follows, type;
- my = kex_buf2prop(&kex->my);
- peer = kex_buf2prop(&kex->peer);
+ my = kex_buf2prop(&kex->my, NULL);
+ peer = kex_buf2prop(&kex->peer, &first_kex_follows);
if (kex->server) {
cprop=peer;
need = 0;
for (mode = 0; mode < MODE_MAX; mode++) {
newkeys = kex->newkeys[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->enc.key_len)
+ need = newkeys->enc.key_len;
+ if (need < newkeys->enc.block_size)
+ need = newkeys->enc.block_size;
if (need < newkeys->mac.key_len)
need = newkeys->mac.key_len;
}
/* XXX need runden? */
kex->we_need = need;
+ /* ignore the next message if the proposals do not match */
+ if (first_kex_follows && !proposals_match(my, peer) &&
+ !(datafellows & SSH_BUG_FIRSTKEX)) {
+ type = packet_read();
+ debug2("skipping next packet (type %u)", type);
+ }
+
kex_prop_free(my);
kex_prop_free(peer);
}
derive_key(Kex *kex, int id, int need, u_char *hash, BIGNUM *shared_secret)
{
Buffer b;
- EVP_MD *evp_md = EVP_sha1();
+ const EVP_MD *evp_md = EVP_sha1();
EVP_MD_CTX md;
char c = id;
int have;
- int mdsz = evp_md->md_size;
+ int mdsz = EVP_MD_size(evp_md);
u_char *digest = xmalloc(roundup(need, mdsz));
buffer_init(&b);
for (i = 0; i < NKEYS; i++)
keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, shared_secret);
- debug("kex_derive_keys");
+ debug2("kex_derive_keys");
for (mode = 0; mode < MODE_MAX; mode++) {
current_keys[mode] = kex->newkeys[mode];
kex->newkeys[mode] = NULL;
return ret;
}
+void
+derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus,
+ u_int8_t cookie[8], u_int8_t id[16])
+{
+ const EVP_MD *evp_md = EVP_md5();
+ EVP_MD_CTX md;
+ u_int8_t nbuf[2048], obuf[EVP_MAX_MD_SIZE];
+ int len;
+
+ EVP_DigestInit(&md, evp_md);
+
+ len = BN_num_bytes(host_modulus);
+ if (len < (512 / 8) || len > sizeof(nbuf))
+ fatal("%s: bad host modulus (len %d)", __func__, len);
+ BN_bn2bin(host_modulus, nbuf);
+ EVP_DigestUpdate(&md, nbuf, len);
+
+ len = BN_num_bytes(server_modulus);
+ if (len < (512 / 8) || len > sizeof(nbuf))
+ fatal("%s: bad server modulus (len %d)", __func__, len);
+ BN_bn2bin(server_modulus, nbuf);
+ EVP_DigestUpdate(&md, nbuf, len);
+
+ EVP_DigestUpdate(&md, cookie, 8);
+
+ EVP_DigestFinal(&md, obuf, NULL);
+ memcpy(id, obuf, 16);
+
+ memset(nbuf, 0, sizeof(nbuf));
+ memset(obuf, 0, sizeof(obuf));
+ memset(&md, 0, sizeof(md));
+}
+
#if defined(DEBUG_KEX) || defined(DEBUG_KEXDH)
void
dump_digest(char *msg, u_char *digest, int len)
andersk / openssh.git / blobdiff