+/* $OpenBSD: kex.c,v 1.82 2009/10/24 11:13:54 andreas Exp $ */
/*
* Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
*
*/
#include "includes.h"
-RCSID("$OpenBSD: kex.c,v 1.50 2002/05/15 15:47:49 mouring Exp $");
+
+#include <sys/param.h>
+
+#include <signal.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
#include <openssl/crypto.h>
-#include "ssh2.h"
#include "xmalloc.h"
+#include "ssh2.h"
#include "buffer.h"
-#include "bufaux.h"
#include "packet.h"
#include "compat.h"
#include "cipher.h"
-#include "kex.h"
#include "key.h"
+#include "kex.h"
#include "log.h"
#include "mac.h"
#include "match.h"
#include "dispatch.h"
#include "monitor.h"
-
-#define KEX_COOKIE_LEN 16
-
-/* Use privilege separation for sshd */
-int use_privsep;
-struct monitor *pmonitor;
-
+#include "roaming.h"
+
+#if OPENSSL_VERSION_NUMBER >= 0x00907000L
+# if defined(HAVE_EVP_SHA256)
+# define evp_ssh_sha256 EVP_sha256
+# else
+extern const EVP_MD *evp_ssh_sha256(void);
+# endif
+#endif
/* prototype */
static void kex_kexinit_finish(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;
+ u_int i;
char **proposal;
- proposal = xmalloc(PROPOSAL_MAX * sizeof(char *));
+ proposal = xcalloc(PROPOSAL_MAX, sizeof(char *));
buffer_init(&b);
buffer_append(&b, buffer_ptr(raw), buffer_len(raw));
}
/* 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);
+ debug2("kex_parse_kexinit: reserved %u ", i);
buffer_free(&b);
return proposal;
}
static void
kex_prop_free(char **proposal)
{
- int i;
+ u_int i;
for (i = 0; i < PROPOSAL_MAX; i++)
xfree(proposal[i]);
xfree(proposal);
}
+/* ARGSUSED */
static void
kex_protocol_error(int type, u_int32_t seq, void *ctxt)
{
/* 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");
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->flags |= KEX_INIT_SENT;
}
+/* ARGSUSED */
void
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");
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 *kex;
- kex = xmalloc(sizeof(*kex));
- memset(kex, 0, sizeof(*kex));
+ kex = xcalloc(1, sizeof(*kex));
buffer_init(&kex->peer);
buffer_init(&kex->my);
kex_prop2buf(&kex->my, proposal);
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);
+ fatal("no matching cipher found: client %s server %s",
+ client, server);
if ((enc->cipher = cipher_by_name(name)) == NULL)
fatal("matching cipher is not supported: %s", name);
enc->name = name;
enc->key_len = cipher_keylen(enc->cipher);
enc->block_size = cipher_blocksize(enc->cipher);
}
+
static void
choose_mac(Mac *mac, char *client, char *server)
{
char *name = match_list(client, server, NULL);
if (name == NULL)
- fatal("no matching mac found: client %s server %s", client, server);
- if (mac_init(mac, name) < 0)
+ fatal("no matching mac found: client %s server %s",
+ client, server);
+ if (mac_setup(mac, name) < 0)
fatal("unsupported mac %s", name);
/* truncate the key */
if (datafellows & SSH_BUG_HMAC)
mac->key = NULL;
mac->enabled = 0;
}
+
static void
choose_comp(Comp *comp, char *client, char *server)
{
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);
}
comp->name = name;
}
+
static void
choose_kex(Kex *k, char *client, char *server)
{
k->name = match_list(client, server, NULL);
if (k->name == NULL)
- fatal("no kex alg");
+ fatal("Unable to negotiate a key exchange method");
if (strcmp(k->name, KEX_DH1) == 0) {
- k->kex_type = DH_GRP1_SHA1;
- } else if (strcmp(k->name, KEX_DHGEX) == 0) {
- k->kex_type = DH_GEX_SHA1;
+ k->kex_type = KEX_DH_GRP1_SHA1;
+ k->evp_md = EVP_sha1();
+ } else if (strcmp(k->name, KEX_DH14) == 0) {
+ k->kex_type = KEX_DH_GRP14_SHA1;
+ k->evp_md = EVP_sha1();
+ } else if (strcmp(k->name, KEX_DHGEX_SHA1) == 0) {
+ k->kex_type = KEX_DH_GEX_SHA1;
+ k->evp_md = EVP_sha1();
+#if OPENSSL_VERSION_NUMBER >= 0x00907000L
+ } else if (strcmp(k->name, KEX_DHGEX_SHA256) == 0) {
+ k->kex_type = KEX_DH_GEX_SHA256;
+ k->evp_md = evp_ssh_sha256();
+#endif
} else
fatal("bad kex alg %s", k->name);
}
+
static void
choose_hostkeyalg(Kex *k, char *client, char *server)
{
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;
sprop=peer;
}
+ /* Check whether server offers roaming */
+ if (!kex->server) {
+ char *roaming;
+ roaming = match_list(KEX_RESUME, peer[PROPOSAL_KEX_ALGS], NULL);
+ if (roaming) {
+ kex->roaming = 1;
+ xfree(roaming);
+ }
+ }
+
/* Algorithm Negotiation */
for (mode = 0; mode < MODE_MAX; mode++) {
- newkeys = xmalloc(sizeof(*newkeys));
- memset(newkeys, 0, sizeof(*newkeys));
+ newkeys = xcalloc(1, sizeof(*newkeys));
kex->newkeys[mode] = newkeys;
- ctos = (!kex->server && mode == MODE_OUT) || (kex->server && mode == MODE_IN);
+ 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;
/* 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, u_int hashlen,
+ BIGNUM *shared_secret)
{
Buffer b;
- const EVP_MD *evp_md = EVP_sha1();
EVP_MD_CTX md;
char c = id;
- int have;
- int mdsz = EVP_MD_size(evp_md);
- u_char *digest = xmalloc(roundup(need, mdsz));
+ u_int have;
+ int mdsz;
+ u_char *digest;
+
+ if ((mdsz = EVP_MD_size(kex->evp_md)) <= 0)
+ fatal("bad kex md size %d", mdsz);
+ digest = xmalloc(roundup(need, mdsz));
buffer_init(&b);
buffer_put_bignum2(&b, shared_secret);
/* K1 = HASH(K || H || "A" || session_id) */
- EVP_DigestInit(&md, evp_md);
+ EVP_DigestInit(&md, kex->evp_md);
if (!(datafellows & SSH_BUG_DERIVEKEY))
EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
- EVP_DigestUpdate(&md, hash, mdsz);
+ EVP_DigestUpdate(&md, hash, hashlen);
EVP_DigestUpdate(&md, &c, 1);
EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
EVP_DigestFinal(&md, digest, NULL);
* Key = K1 || K2 || ... || Kn
*/
for (have = mdsz; need > have; have += mdsz) {
- EVP_DigestInit(&md, evp_md);
+ EVP_DigestInit(&md, kex->evp_md);
if (!(datafellows & SSH_BUG_DERIVEKEY))
EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
- EVP_DigestUpdate(&md, hash, mdsz);
+ EVP_DigestUpdate(&md, hash, hashlen);
EVP_DigestUpdate(&md, digest, have);
EVP_DigestFinal(&md, digest + have, NULL);
}
#define NKEYS 6
void
-kex_derive_keys(Kex *kex, u_char *hash, BIGNUM *shared_secret)
+kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, 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);
+ for (i = 0; i < NKEYS; i++) {
+ keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen,
+ 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;
- ctos = (!kex->server && mode == MODE_OUT) || (kex->server && mode == MODE_IN);
+ ctos = (!kex->server && mode == MODE_OUT) ||
+ (kex->server && mode == MODE_IN);
current_keys[mode]->enc.iv = keys[ctos ? 0 : 1];
current_keys[mode]->enc.key = keys[ctos ? 2 : 3];
current_keys[mode]->mac.key = keys[ctos ? 4 : 5];
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++) {
+ for (i = 0; i < len; i++) {
fprintf(stderr, "%02x", digest[i]);
if (i%32 == 31)
fprintf(stderr, "\n");
andersk / openssh.git / blobdiff