Ejemplo n.º 1
0
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;
}
Ejemplo n.º 2
0
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));
}
Ejemplo n.º 3
0
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;
}
Ejemplo n.º 4
0
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;
}