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; }
void ssh_packet_get_bignum2(struct ssh *ssh, BIGNUM * value) { int r; if ((r = sshpkt_get_bignum2(ssh, value)) != 0) fatal("%s: %s", __func__, ssh_err(r)); }
static int input_kex_dh_gex_reply(int type, u_int32_t seq, struct ssh *ssh) { Kex *kex = ssh->kex; BIGNUM *dh_server_pub = NULL, *shared_secret = NULL; struct sshkey *server_host_key; u_char *kbuf = NULL, *hash, *signature = NULL, *server_host_key_blob = NULL; size_t klen = 0, slen, sbloblen, hashlen; int kout, r; debug("got SSH2_MSG_KEX_DH_GEX_REPLY"); if (kex->verify_host_key == NULL) { r = SSH_ERR_INVALID_ARGUMENT; goto out; } /* key, cert */ if ((r = sshpkt_get_string(ssh, &server_host_key_blob, &sbloblen)) != 0 || (r = sshkey_from_blob(server_host_key_blob, sbloblen, &server_host_key)) != 0) goto out; if (server_host_key->type != kex->hostkey_type) { r = SSH_ERR_KEY_TYPE_MISMATCH; goto out; } if (kex->verify_host_key(server_host_key, ssh) == -1) { r = SSH_ERR_SIGNATURE_INVALID; goto out; } /* DH parameter f, server public DH key */ if ((dh_server_pub = BN_new()) == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } /* signed H */ if ((r = sshpkt_get_bignum2(ssh, dh_server_pub)) != 0 || (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 || (r = sshpkt_get_end(ssh)) != 0) goto out; #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 if (!dh_pub_is_valid(kex->dh, dh_server_pub)) { sshpkt_disconnect(ssh, "bad server public DH value"); r = SSH_ERR_MESSAGE_INCOMPLETE; goto out; } klen = DH_size(kex->dh); if ((kbuf = malloc(klen)) == NULL || (shared_secret = BN_new()) == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } if ((kout = DH_compute_key(kbuf, dh_server_pub, kex->dh)) < 0 || BN_bin2bn(kbuf, kout, shared_secret) == NULL) { r = SSH_ERR_LIBCRYPTO_ERROR; goto out; } #ifdef DEBUG_KEXDH dump_digest("shared secret", kbuf, kout); #endif if (ssh->compat & SSH_OLD_DHGEX) kex->min = kex->max = -1; /* calc and verify H */ if ((r = kexgex_hash( kex->evp_md, kex->client_version_string, kex->server_version_string, sshbuf_ptr(kex->my), sshbuf_len(kex->my), sshbuf_ptr(kex->peer), sshbuf_len(kex->peer), server_host_key_blob, sbloblen, kex->min, kex->nbits, kex->max, kex->dh->p, kex->dh->g, kex->dh->pub_key, dh_server_pub, shared_secret, &hash, &hashlen)) != 0) goto out; if ((r = sshkey_verify(server_host_key, signature, slen, hash, hashlen, ssh->compat)) != 0) goto out; /* save session id */ if (kex->session_id == NULL) { kex->session_id_len = hashlen; kex->session_id = malloc(kex->session_id_len); if (kex->session_id == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } memcpy(kex->session_id, hash, kex->session_id_len); } if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0) r = kex_send_newkeys(ssh); out: DH_free(kex->dh); kex->dh = NULL; if (server_host_key_blob) free(server_host_key_blob); if (server_host_key) sshkey_free(server_host_key); if (dh_server_pub) BN_clear_free(dh_server_pub); if (kbuf) { bzero(kbuf, klen); free(kbuf); } if (shared_secret) BN_clear_free(shared_secret); if (signature) free(signature); return r; }
int input_kex_dh_init(int type, u_int32_t seq, void *ctxt) { struct ssh *ssh = ctxt; struct kex *kex = ssh->kex; BIGNUM *shared_secret = NULL, *dh_client_pub = NULL; struct sshkey *server_host_public, *server_host_private; u_char *kbuf = NULL, *signature = NULL, *server_host_key_blob = NULL; u_char hash[SSH_DIGEST_MAX_LENGTH]; size_t sbloblen, slen; size_t klen = 0, hashlen; int kout, r; if (kex->load_host_public_key == NULL || kex->load_host_private_key == NULL) { r = SSH_ERR_INVALID_ARGUMENT; goto out; } server_host_public = kex->load_host_public_key(kex->hostkey_type, kex->hostkey_nid, ssh); server_host_private = kex->load_host_private_key(kex->hostkey_type, kex->hostkey_nid, ssh); if (server_host_public == NULL) { r = SSH_ERR_NO_HOSTKEY_LOADED; goto out; } /* key, cert */ if ((dh_client_pub = BN_new()) == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } if ((r = sshpkt_get_bignum2(ssh, dh_client_pub)) != 0 || (r = sshpkt_get_end(ssh)) != 0) goto out; #ifdef DEBUG_KEXDH fprintf(stderr, "dh_client_pub= "); BN_print_fp(stderr, dh_client_pub); fprintf(stderr, "\n"); debug("bits %d", BN_num_bits(dh_client_pub)); #endif #ifdef DEBUG_KEXDH DHparams_print_fp(stderr, kex->dh); fprintf(stderr, "pub= "); BN_print_fp(stderr, kex->dh->pub_key); fprintf(stderr, "\n"); #endif if (!dh_pub_is_valid(kex->dh, dh_client_pub)) { sshpkt_disconnect(ssh, "bad client public DH value"); r = SSH_ERR_MESSAGE_INCOMPLETE; goto out; } klen = DH_size(kex->dh); if ((kbuf = malloc(klen)) == NULL || (shared_secret = BN_new()) == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } if ((kout = DH_compute_key(kbuf, dh_client_pub, kex->dh)) < 0 || BN_bin2bn(kbuf, kout, shared_secret) == NULL) { r = SSH_ERR_LIBCRYPTO_ERROR; goto out; } #ifdef DEBUG_KEXDH dump_digest("shared secret", kbuf, kout); #endif if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob, &sbloblen)) != 0) goto out; /* calc H */ hashlen = sizeof(hash); if ((r = kex_dh_hash( kex->client_version_string, kex->server_version_string, sshbuf_ptr(kex->peer), sshbuf_len(kex->peer), sshbuf_ptr(kex->my), sshbuf_len(kex->my), server_host_key_blob, sbloblen, dh_client_pub, kex->dh->pub_key, shared_secret, hash, &hashlen)) != 0) goto out; /* save session id := H */ if (kex->session_id == NULL) { kex->session_id_len = hashlen; kex->session_id = malloc(kex->session_id_len); if (kex->session_id == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } memcpy(kex->session_id, hash, kex->session_id_len); } /* sign H */ if ((r = kex->sign(server_host_private, server_host_public, &signature, &slen, hash, hashlen, kex->hostkey_alg, ssh->compat)) < 0) goto out; /* destroy_sensitive_data(); */ /* send server hostkey, DH pubkey 'f' and singed H */ if ((r = sshpkt_start(ssh, SSH2_MSG_KEXDH_REPLY)) != 0 || (r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 || (r = sshpkt_put_bignum2(ssh, kex->dh->pub_key)) != 0 || /* f */ (r = sshpkt_put_string(ssh, signature, slen)) != 0 || (r = sshpkt_send(ssh)) != 0) goto out; if ((r = kex_derive_keys_bn(ssh, hash, hashlen, shared_secret)) == 0) r = kex_send_newkeys(ssh); out: explicit_bzero(hash, sizeof(hash)); DH_free(kex->dh); kex->dh = NULL; if (dh_client_pub) BN_clear_free(dh_client_pub); if (kbuf) { explicit_bzero(kbuf, klen); free(kbuf); } if (shared_secret) BN_clear_free(shared_secret); free(server_host_key_blob); free(signature); return r; }