*/
#include "includes.h"
-RCSID("$OpenBSD: kex.c,v 1.52 2002/11/21 22:45:31 markus Exp $");
+RCSID("$OpenBSD: kex.c,v 1.64 2005/07/25 11:59:39 markus Exp $");
#include <openssl/crypto.h>
#define KEX_COOKIE_LEN 16
-/* Use privilege separation for sshd */
-int use_privsep;
-struct monitor *pmonitor;
-
-
/* prototype */
static void kex_kexinit_finish(Kex *);
static void kex_choose_conf(Kex *);
static void
kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
{
- int i;
+ u_int i;
buffer_clear(b);
/*
/* 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_prop_free(char **proposal)
{
- int i;
+ u_int i;
for (i = 0; i < PROPOSAL_MAX; i++)
xfree(proposal[i]);
void
kex_send_kexinit(Kex *kex)
{
- u_int32_t rand = 0;
+ u_int32_t rnd = 0;
u_char *cookie;
- int i;
+ u_int i;
if (kex == NULL) {
error("kex_send_kexinit: no kex, cannot rekey");
cookie = buffer_ptr(&kex->my);
for (i = 0; i < KEX_COOKIE_LEN; i++) {
if (i % 4 == 0)
- rand = arc4random();
- cookie[i] = rand;
- rand >>= 8;
+ rnd = arc4random();
+ cookie[i] = rnd;
+ rnd >>= 8;
}
packet_start(SSH2_MSG_KEXINIT);
packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
{
char *ptr;
- int dlen;
- int i;
+ u_int i, dlen;
Kex *kex = (Kex *)ctxt;
debug("SSH2_MSG_KEXINIT received");
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 comp found: client %s server %s", client, server);
- if (strcmp(name, "zlib") == 0) {
- comp->type = 1;
+ if (strcmp(name, "zlib@openssh.com") == 0) {
+ comp->type = COMP_DELAYED;
+ } else if (strcmp(name, "zlib") == 0) {
+ comp->type = COMP_ZLIB;
} else if (strcmp(name, "none") == 0) {
- comp->type = 0;
+ comp->type = COMP_NONE;
} else {
fatal("unsupported comp %s", name);
}
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)
{
char **my, **peer;
char **cprop, **sprop;
int nenc, nmac, ncomp;
- int mode;
- int ctos; /* direction: if true client-to-server */
- int need;
+ u_int mode, ctos, 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;
/* 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);
}
static u_char *
-derive_key(Kex *kex, int id, int need, u_char *hash, BIGNUM *shared_secret)
+derive_key(Kex *kex, int id, u_int need, u_char *hash, BIGNUM *shared_secret)
{
Buffer b;
const EVP_MD *evp_md = EVP_sha1();
EVP_MD_CTX md;
char c = id;
- int have;
+ u_int have;
int mdsz = EVP_MD_size(evp_md);
- u_char *digest = xmalloc(roundup(need, mdsz));
+ u_char *digest;
+
+ if (mdsz < 0)
+ fatal("derive_key: mdsz < 0");
+ digest = xmalloc(roundup(need, mdsz));
buffer_init(&b);
buffer_put_bignum2(&b, shared_secret);
kex_derive_keys(Kex *kex, u_char *hash, BIGNUM *shared_secret)
{
u_char *keys[NKEYS];
- int i, mode, ctos;
+ u_int i, mode, ctos;
for (i = 0; i < NKEYS; i++)
keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, shared_secret);
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) || (u_int)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) || (u_int)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)
{
- int i;
+ u_int i;
fprintf(stderr, "%s\n", msg);
for (i = 0; i< len; i++) {