X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/76bf34f1db3a4f70a4614bd848b13ce16d4948ea..bfd17430a8676427695e67e0c0c6d4fe3eaef7ba:/kex.c diff --git a/kex.c b/kex.c index 194a865a..5dce335f 100644 --- a/kex.c +++ b/kex.c @@ -23,7 +23,7 @@ */ #include "includes.h" -RCSID("$OpenBSD: kex.c,v 1.49 2002/03/26 23:14:51 markus Exp $"); +RCSID("$OpenBSD: kex.c,v 1.64 2005/07/25 11:59:39 markus Exp $"); #include @@ -44,11 +44,6 @@ RCSID("$OpenBSD: kex.c,v 1.49 2002/03/26 23:14:51 markus Exp $"); #define KEX_COOKIE_LEN 16 -/* Use privilege separation for sshd */ -int use_privsep; -struct monitor *monitor; - - /* prototype */ static void kex_kexinit_finish(Kex *); static void kex_choose_conf(Kex *); @@ -57,7 +52,7 @@ static void kex_choose_conf(Kex *); static void kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) { - int i; + u_int i; buffer_clear(b); /* @@ -74,7 +69,7 @@ kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) /* parse buffer and return algorithm proposal */ static char ** -kex_buf2prop(Buffer *raw) +kex_buf2prop(Buffer *raw, int *first_kex_follows) { Buffer b; int i; @@ -94,6 +89,8 @@ kex_buf2prop(Buffer *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); @@ -104,7 +101,7 @@ kex_buf2prop(Buffer *raw) static void kex_prop_free(char **proposal) { - int i; + u_int i; for (i = 0; i < PROPOSAL_MAX; i++) xfree(proposal[i]); @@ -135,7 +132,7 @@ kex_finish(Kex *kex) /* 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"); @@ -151,9 +148,9 @@ kex_finish(Kex *kex) 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"); @@ -171,9 +168,9 @@ kex_send_kexinit(Kex *kex) 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)); @@ -186,8 +183,7 @@ 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"); @@ -202,8 +198,8 @@ kex_input_kexinit(int type, u_int32_t seq, void *ctxt) 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); @@ -235,14 +231,10 @@ kex_kexinit_finish(Kex *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); } } @@ -283,10 +275,12 @@ 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); } @@ -299,9 +293,11 @@ choose_kex(Kex *k, 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); } @@ -317,6 +313,30 @@ 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) { @@ -324,12 +344,11 @@ 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; @@ -373,20 +392,31 @@ kex_choose_conf(Kex *kex) /* 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); @@ -428,12 +458,12 @@ void 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); - 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; @@ -454,11 +484,44 @@ kex_get_newkeys(int mode) 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++) {