DH * mm_choose_dh(int min, int nbits, int max) { BIGNUM *p, *g; int success = 0; Buffer m; buffer_init(&m); buffer_put_int(&m, min); buffer_put_int(&m, nbits); buffer_put_int(&m, max); mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_MODULI, &m); debug3("%s: waiting for MONITOR_ANS_MODULI", __func__); mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_MODULI, &m); success = buffer_get_char(&m); if (success == 0) fatal("%s: MONITOR_ANS_MODULI failed", __func__); if ((p = BN_new()) == NULL) fatal("%s: BN_new failed", __func__); if ((g = BN_new()) == NULL) fatal("%s: BN_new failed", __func__); buffer_get_bignum2(&m, p); buffer_get_bignum2(&m, g); debug3("%s: remaining %d", __func__, buffer_len(&m)); buffer_free(&m); return (dh_new_group(g, p)); }
static int input_kex_dh_gex_group(int type, u_int32_t seq, void *ctxt) { struct ssh *ssh = ctxt; struct kex *kex = ssh->kex; BIGNUM *p = NULL, *g = NULL; int r, bits; debug("got SSH2_MSG_KEX_DH_GEX_GROUP"); if ((p = BN_new()) == NULL || (g = BN_new()) == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } if ((r = sshpkt_get_bignum2(ssh, p)) != 0 || (r = sshpkt_get_bignum2(ssh, g)) != 0 || (r = sshpkt_get_end(ssh)) != 0) goto out; if ((bits = BN_num_bits(p)) < 0 || (u_int)bits < kex->min || (u_int)bits > kex->max) { r = SSH_ERR_DH_GEX_OUT_OF_RANGE; goto out; } if ((kex->dh = dh_new_group(g, p)) == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } p = g = NULL; /* belong to kex->dh now */ /* generate and send 'e', client DH public key */ if ((r = dh_gen_key(kex->dh, kex->we_need * 8)) != 0 || (r = sshpkt_start(ssh, SSH2_MSG_KEX_DH_GEX_INIT)) != 0 || (r = sshpkt_put_bignum2(ssh, kex->dh->pub_key)) != 0 || (r = sshpkt_send(ssh)) != 0) goto out; debug("SSH2_MSG_KEX_DH_GEX_INIT sent"); #ifdef DEBUG_KEXDH DHparams_print_fp(stderr, kex->dh); fprintf(stderr, "pub= "); BN_print_fp(stderr, kex->dh->pub_key); fprintf(stderr, "\n"); #endif ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_GROUP, NULL); ssh_dispatch_set(ssh, SSH2_MSG_KEX_DH_GEX_REPLY, &input_kex_dh_gex_reply); r = 0; out: if (p) BN_clear_free(p); if (g) BN_clear_free(g); return r; }
DH * choose_dh(int min, int wantbits, int max) { FILE *f; char line[4096]; int best, bestcount, which; int linenum; struct dhgroup dhg; if ((f = fopen(_PATH_DH_MODULI, "r")) == NULL) { logit("WARNING: could open open %s (%s), using fixed modulus", _PATH_DH_MODULI, strerror(errno)); return (dh_new_group_fallback(max)); } linenum = 0; best = bestcount = 0; while (fgets(line, sizeof(line), f)) { linenum++; if (!parse_prime(linenum, line, &dhg)) continue; BN_clear_free(dhg.g); BN_clear_free(dhg.p); if (dhg.size > max || dhg.size < min) continue; if ((dhg.size > wantbits && dhg.size < best) || (dhg.size > best && best < wantbits)) { best = dhg.size; bestcount = 0; } if (dhg.size == best) bestcount++; } rewind(f); if (bestcount == 0) { fclose(f); logit("WARNING: no suitable primes in %s", _PATH_DH_MODULI); return (dh_new_group_fallback(max)); } linenum = 0; which = arc4random_uniform(bestcount); while (fgets(line, sizeof(line), f)) { if (!parse_prime(linenum, line, &dhg)) continue; if ((dhg.size > max || dhg.size < min) || dhg.size != best || linenum++ != which) { BN_clear_free(dhg.g); BN_clear_free(dhg.p); continue; } break; } fclose(f); if (linenum != which+1) { logit("WARNING: line %d disappeared in %s, giving up", which, _PATH_DH_MODULI); return (dh_new_group_fallback(max)); } return (dh_new_group(dhg.g, dhg.p)); }
void kexgss_client(Kex *kex) { gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER; gss_buffer_desc recv_tok, gssbuf, msg_tok, *token_ptr; Gssctxt *ctxt; OM_uint32 maj_status, min_status, ret_flags; u_int klen, kout, slen = 0, hashlen, strlen; DH *dh; BIGNUM *dh_server_pub = NULL; BIGNUM *shared_secret = NULL; BIGNUM *p = NULL; BIGNUM *g = NULL; u_char *kbuf, *hash; u_char *serverhostkey = NULL; u_char *empty = ""; char *msg; char *lang; int type = 0; int first = 1; int nbits = 0, min = DH_GRP_MIN, max = DH_GRP_MAX; /* Initialise our GSSAPI world */ ssh_gssapi_build_ctx(&ctxt); if (ssh_gssapi_id_kex(ctxt, kex->name, kex->kex_type) == GSS_C_NO_OID) fatal("Couldn't identify host exchange"); if (ssh_gssapi_import_name(ctxt, kex->gss_host)) fatal("Couldn't import hostname"); if (kex->gss_client && ssh_gssapi_client_identity(ctxt, kex->gss_client)) fatal("Couldn't acquire client credentials"); switch (kex->kex_type) { case KEX_GSS_GRP1_SHA1: dh = dh_new_group1(); break; case KEX_GSS_GRP14_SHA1: dh = dh_new_group14(); break; case KEX_GSS_GEX_SHA1: debug("Doing group exchange\n"); nbits = dh_estimate(kex->we_need * 8); packet_start(SSH2_MSG_KEXGSS_GROUPREQ); packet_put_int(min); packet_put_int(nbits); packet_put_int(max); packet_send(); packet_read_expect(SSH2_MSG_KEXGSS_GROUP); if ((p = BN_new()) == NULL) fatal("BN_new() failed"); packet_get_bignum2(p); if ((g = BN_new()) == NULL) fatal("BN_new() failed"); packet_get_bignum2(g); packet_check_eom(); if (BN_num_bits(p) < min || BN_num_bits(p) > max) fatal("GSSGRP_GEX group out of range: %d !< %d !< %d", min, BN_num_bits(p), max); dh = dh_new_group(g, p); break; default: fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type); } /* Step 1 - e is dh->pub_key */ dh_gen_key(dh, kex->we_need * 8); /* This is f, we initialise it now to make life easier */ dh_server_pub = BN_new(); if (dh_server_pub == NULL) fatal("dh_server_pub == NULL"); token_ptr = GSS_C_NO_BUFFER; do { debug("Calling gss_init_sec_context"); maj_status = ssh_gssapi_init_ctx(ctxt, kex->gss_deleg_creds, token_ptr, &send_tok, &ret_flags); if (GSS_ERROR(maj_status)) { if (send_tok.length != 0) { packet_start(SSH2_MSG_KEXGSS_CONTINUE); packet_put_string(send_tok.value, send_tok.length); } fatal("gss_init_context failed"); } /* If we've got an old receive buffer get rid of it */ if (token_ptr != GSS_C_NO_BUFFER) xfree(recv_tok.value); if (maj_status == GSS_S_COMPLETE) { /* If mutual state flag is not true, kex fails */ if (!(ret_flags & GSS_C_MUTUAL_FLAG)) fatal("Mutual authentication failed"); /* If integ avail flag is not true kex fails */ if (!(ret_flags & GSS_C_INTEG_FLAG)) fatal("Integrity check failed"); } /* * If we have data to send, then the last message that we * received cannot have been a 'complete'. */ if (send_tok.length != 0) { if (first) { packet_start(SSH2_MSG_KEXGSS_INIT); packet_put_string(send_tok.value, send_tok.length); packet_put_bignum2(dh->pub_key); first = 0; } else { packet_start(SSH2_MSG_KEXGSS_CONTINUE); packet_put_string(send_tok.value, send_tok.length); } packet_send(); gss_release_buffer(&min_status, &send_tok); /* If we've sent them data, they should reply */ do { type = packet_read(); if (type == SSH2_MSG_KEXGSS_HOSTKEY) { debug("Received KEXGSS_HOSTKEY"); if (serverhostkey) fatal("Server host key received more than once"); serverhostkey = packet_get_string(&slen); } } while (type == SSH2_MSG_KEXGSS_HOSTKEY); switch (type) { case SSH2_MSG_KEXGSS_CONTINUE: debug("Received GSSAPI_CONTINUE"); if (maj_status == GSS_S_COMPLETE) fatal("GSSAPI Continue received from server when complete"); recv_tok.value = packet_get_string(&strlen); recv_tok.length = strlen; break; case SSH2_MSG_KEXGSS_COMPLETE: debug("Received GSSAPI_COMPLETE"); packet_get_bignum2(dh_server_pub); msg_tok.value = packet_get_string(&strlen); msg_tok.length = strlen; /* Is there a token included? */ if (packet_get_char()) { recv_tok.value= packet_get_string(&strlen); recv_tok.length = strlen; /* If we're already complete - protocol error */ if (maj_status == GSS_S_COMPLETE) packet_disconnect("Protocol error: received token when complete"); } else { /* No token included */ if (maj_status != GSS_S_COMPLETE) packet_disconnect("Protocol error: did not receive final token"); } break; case SSH2_MSG_KEXGSS_ERROR: debug("Received Error"); maj_status = packet_get_int(); min_status = packet_get_int(); msg = packet_get_string(NULL); lang = packet_get_string(NULL); fatal("GSSAPI Error: \n%.400s",msg); default: packet_disconnect("Protocol error: didn't expect packet type %d", type); } token_ptr = &recv_tok; } else { /* No data, and not complete */ if (maj_status != GSS_S_COMPLETE) fatal("Not complete, and no token output"); } } while (maj_status & GSS_S_CONTINUE_NEEDED); /* * We _must_ have received a COMPLETE message in reply from the * server, which will have set dh_server_pub and msg_tok */ if (type != SSH2_MSG_KEXGSS_COMPLETE) fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it"); /* Check f in range [1, p-1] */ if (!dh_pub_is_valid(dh, dh_server_pub)) packet_disconnect("bad server public DH value"); /* compute K=f^x mod p */ klen = DH_size(dh); kbuf = xmalloc(klen); kout = DH_compute_key(kbuf, dh_server_pub, dh); if (kout < 0) fatal("DH_compute_key: failed"); shared_secret = BN_new(); if (shared_secret == NULL) fatal("kexgss_client: BN_new failed"); if (BN_bin2bn(kbuf, kout, shared_secret) == NULL) fatal("kexdh_client: BN_bin2bn failed"); memset(kbuf, 0, klen); xfree(kbuf); switch (kex->kex_type) { case KEX_GSS_GRP1_SHA1: case KEX_GSS_GRP14_SHA1: kex_dh_hash( kex->client_version_string, kex->server_version_string, buffer_ptr(&kex->my), buffer_len(&kex->my), buffer_ptr(&kex->peer), buffer_len(&kex->peer), (serverhostkey ? serverhostkey : empty), slen, dh->pub_key, /* e */ dh_server_pub, /* f */ shared_secret, /* K */ &hash, &hashlen ); break; case KEX_GSS_GEX_SHA1: kexgex_hash( kex->evp_md, kex->client_version_string, kex->server_version_string, buffer_ptr(&kex->my), buffer_len(&kex->my), buffer_ptr(&kex->peer), buffer_len(&kex->peer), (serverhostkey ? serverhostkey : empty), slen, min, nbits, max, dh->p, dh->g, dh->pub_key, dh_server_pub, shared_secret, &hash, &hashlen ); break; default: fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type); } gssbuf.value = hash; gssbuf.length = hashlen; /* Verify that the hash matches the MIC we just got. */ if (GSS_ERROR(ssh_gssapi_checkmic(ctxt, &gssbuf, &msg_tok))) packet_disconnect("Hash's MIC didn't verify"); xfree(msg_tok.value); DH_free(dh); if (serverhostkey) xfree(serverhostkey); BN_clear_free(dh_server_pub); /* save session id */ if (kex->session_id == NULL) { kex->session_id_len = hashlen; kex->session_id = xmalloc(kex->session_id_len); memcpy(kex->session_id, hash, kex->session_id_len); } if (kex->gss_deleg_creds) ssh_gssapi_credentials_updated(ctxt); if (gss_kex_context == NULL) gss_kex_context = ctxt; else ssh_gssapi_delete_ctx(&ctxt); kex_derive_keys(kex, hash, hashlen, shared_secret); BN_clear_free(shared_secret); kex_finish(kex); }
void kexgex_client(Kex *kex) { BIGNUM *dh_server_pub = NULL, *shared_secret = NULL; BIGNUM *p = NULL, *g = NULL; Key *server_host_key; u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL; u_int klen, slen, sbloblen, hashlen; int kout; int min, max, nbits; DH *dh; nbits = dh_estimate(kex->dh_need * 8); if (datafellows & SSH_OLD_DHGEX) { /* Old GEX request */ packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST_OLD); packet_put_int(nbits); min = DH_GRP_MIN; max = DH_GRP_MAX; debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD(%u) sent", nbits); } else { /* New GEX request */ min = DH_GRP_MIN; max = DH_GRP_MAX; packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST); packet_put_int(min); packet_put_int(nbits); packet_put_int(max); debug("SSH2_MSG_KEX_DH_GEX_REQUEST(%u<%u<%u) sent", min, nbits, max); } #ifdef DEBUG_KEXDH fprintf(stderr, "\nmin = %d, nbits = %d, max = %d\n", min, nbits, max); #endif packet_send(); debug("expecting SSH2_MSG_KEX_DH_GEX_GROUP"); packet_read_expect(SSH2_MSG_KEX_DH_GEX_GROUP); if ((p = BN_new()) == NULL) fatal("BN_new"); packet_get_bignum2(p); if ((g = BN_new()) == NULL) fatal("BN_new"); packet_get_bignum2(g); packet_check_eom(); if (BN_num_bits(p) < min || BN_num_bits(p) > max) fatal("DH_GEX group out of range: %d !< %d !< %d", min, BN_num_bits(p), max); dh = dh_new_group(g, p); dh_gen_key(dh, kex->we_need * 8); #ifdef DEBUG_KEXDH DHparams_print_fp(stderr, dh); fprintf(stderr, "pub= "); BN_print_fp(stderr, dh->pub_key); fprintf(stderr, "\n"); #endif debug("SSH2_MSG_KEX_DH_GEX_INIT sent"); /* generate and send 'e', client DH public key */ packet_start(SSH2_MSG_KEX_DH_GEX_INIT); packet_put_bignum2(dh->pub_key); packet_send(); debug("expecting SSH2_MSG_KEX_DH_GEX_REPLY"); packet_read_expect(SSH2_MSG_KEX_DH_GEX_REPLY); /* key, cert */ server_host_key_blob = packet_get_string(&sbloblen); server_host_key = key_from_blob(server_host_key_blob, sbloblen); if (server_host_key == NULL) fatal("cannot decode server_host_key_blob"); if (server_host_key->type != kex->hostkey_type) fatal("type mismatch for decoded server_host_key_blob"); if (kex->verify_host_key == NULL) fatal("cannot verify server_host_key"); if (kex->verify_host_key(server_host_key) == -1) fatal("server_host_key verification failed"); /* DH parameter f, server public DH key */ if ((dh_server_pub = BN_new()) == NULL) fatal("dh_server_pub == NULL"); packet_get_bignum2(dh_server_pub); #ifdef DEBUG_KEXDH fprintf(stderr, "dh_server_pub= "); BN_print_fp(stderr, dh_server_pub); fprintf(stderr, "\n"); debug("bits %d", BN_num_bits(dh_server_pub)); #endif /* signed H */ signature = packet_get_string(&slen); packet_check_eom(); if (!dh_pub_is_valid(dh, dh_server_pub)) packet_disconnect("bad server public DH value"); klen = DH_size(dh); kbuf = xmalloc(klen); if ((kout = DH_compute_key(kbuf, dh_server_pub, dh)) < 0) fatal("DH_compute_key: failed"); #ifdef DEBUG_KEXDH dump_digest("shared secret", kbuf, kout); #endif if ((shared_secret = BN_new()) == NULL) fatal("kexgex_client: BN_new failed"); if (BN_bin2bn(kbuf, kout, shared_secret) == NULL) fatal("kexgex_client: BN_bin2bn failed"); explicit_bzero(kbuf, klen); free(kbuf); if (datafellows & SSH_OLD_DHGEX) min = max = -1; /* calc and verify H */ kexgex_hash( kex->hash_alg, kex->client_version_string, kex->server_version_string, buffer_ptr(&kex->my), buffer_len(&kex->my), buffer_ptr(&kex->peer), buffer_len(&kex->peer), server_host_key_blob, sbloblen, min, nbits, max, dh->p, dh->g, dh->pub_key, dh_server_pub, shared_secret, &hash, &hashlen ); /* have keys, free DH */ DH_free(dh); free(server_host_key_blob); BN_clear_free(dh_server_pub); if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1) fatal("key_verify failed for server_host_key"); key_free(server_host_key); free(signature); /* save session id */ if (kex->session_id == NULL) { kex->session_id_len = hashlen; kex->session_id = xmalloc(kex->session_id_len); memcpy(kex->session_id, hash, kex->session_id_len); } kex_derive_keys_bn(kex, hash, hashlen, shared_secret); BN_clear_free(shared_secret); kex_finish(kex); }
DH * choose_dh(int min, int wantbits, int max) { FILE *f; char line[2048]; int best, bestcount, which; int linenum; struct dhgroup dhg; if ((f = fopen(_PATH_DH_MODULI, "r")) == NULL && (f = fopen(_PATH_DH_PRIMES, "r")) == NULL) { log("WARNING: %s does not exist, using old modulus", _PATH_DH_MODULI); return (dh_new_group1()); } linenum = 0; best = bestcount = 0; while (fgets(line, sizeof(line), f)) { linenum++; if (!parse_prime(linenum, line, &dhg)) continue; BN_clear_free(dhg.g); BN_clear_free(dhg.p); if (dhg.size > max || dhg.size < min) continue; if ((dhg.size > wantbits && dhg.size < best) || (dhg.size > best && best < wantbits)) { best = dhg.size; bestcount = 0; } if (dhg.size == best) bestcount++; } rewind(f); if (bestcount == 0) { fclose(f); log("WARNING: no suitable primes in %s", _PATH_DH_PRIMES); return (NULL); } linenum = 0; which = arc4random() % bestcount; while (fgets(line, sizeof(line), f)) { if (!parse_prime(linenum, line, &dhg)) continue; if ((dhg.size > max || dhg.size < min) || dhg.size != best || linenum++ != which) { BN_clear_free(dhg.g); BN_clear_free(dhg.p); continue; } break; } fclose(f); if (linenum != which+1) fatal("WARNING: line %d disappeared in %s, giving up", which, _PATH_DH_PRIMES); return (dh_new_group(dhg.g, dhg.p)); }