5 * Author: Tatu Ylonen <ylo@cs.hut.fi>
7 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
10 * Created: Wed Mar 29 01:30:28 1995 ylo
12 * Functions for connecting the local authentication agent.
17 RCSID("$OpenBSD: authfd.c,v 1.22 2000/07/16 08:27:20 markus Exp $");
26 #include <openssl/rsa.h>
27 #include <openssl/dsa.h>
28 #include <openssl/evp.h>
34 int ssh_agent_get_reply(AuthenticationConnection *auth);
36 /* Returns the number of the authentication fd, or -1 if there is none. */
39 ssh_get_authentication_socket()
41 const char *authsocket;
43 struct sockaddr_un sunaddr;
45 authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
49 sunaddr.sun_family = AF_UNIX;
50 strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
52 sock = socket(AF_UNIX, SOCK_STREAM, 0);
57 if (fcntl(sock, F_SETFD, 1) == -1) {
61 if (connect(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
69 * Closes the agent socket if it should be closed (depends on how it was
70 * obtained). The argument must have been returned by
71 * ssh_get_authentication_socket().
75 ssh_close_authentication_socket(int sock)
77 if (getenv(SSH_AUTHSOCKET_ENV_NAME))
82 * Opens and connects a private socket for communication with the
83 * authentication agent. Returns the file descriptor (which must be
84 * shut down and closed by the caller when no longer needed).
85 * Returns NULL if an error occurred and the connection could not be
89 AuthenticationConnection *
90 ssh_get_authentication_connection()
92 AuthenticationConnection *auth;
95 sock = ssh_get_authentication_socket();
98 * Fail if we couldn't obtain a connection. This happens if we
99 * exited due to a timeout.
104 auth = xmalloc(sizeof(*auth));
106 buffer_init(&auth->packet);
107 buffer_init(&auth->identities);
114 * Closes the connection to the authentication agent and frees any associated
119 ssh_close_authentication_connection(AuthenticationConnection *ac)
121 buffer_free(&ac->packet);
122 buffer_free(&ac->identities);
128 * Returns the first authentication identity held by the agent.
129 * Returns true if an identity is available, 0 otherwise.
130 * The caller must initialize the integers before the call, and free the
131 * comment after a successful call (before calling ssh_get_next_identity).
135 ssh_get_first_identity(AuthenticationConnection *auth,
136 BIGNUM *e, BIGNUM *n, char **comment)
138 unsigned char msg[8192];
142 * Send a message to the agent requesting for a list of the
143 * identities it can represent.
146 msg[4] = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
147 if (atomicio(write, auth->fd, msg, 5) != 5) {
148 error("write auth->fd: %.100s", strerror(errno));
151 /* Read the length of the response. XXX implement timeouts here. */
154 l = read(auth->fd, msg + 4 - len, len);
156 error("read auth->fd: %.100s", strerror(errno));
163 * Extract the length, and check it for sanity. (We cannot trust
164 * authentication agents).
166 len = GET_32BIT(msg);
167 if (len < 1 || len > 256 * 1024)
168 fatal("Authentication reply message too long: %d\n", len);
170 /* Read the packet itself. */
171 buffer_clear(&auth->identities);
176 l = read(auth->fd, msg, l);
178 fatal("Incomplete authentication reply.");
179 buffer_append(&auth->identities, (char *) msg, l);
183 /* Get message type, and verify that we got a proper answer. */
184 buffer_get(&auth->identities, (char *) msg, 1);
185 if (msg[0] != SSH_AGENT_RSA_IDENTITIES_ANSWER)
186 fatal("Bad authentication reply message type: %d", msg[0]);
188 /* Get the number of entries in the response and check it for sanity. */
189 auth->howmany = buffer_get_int(&auth->identities);
190 if (auth->howmany > 1024)
191 fatal("Too many identities in authentication reply: %d\n", auth->howmany);
193 /* Return the first entry (if any). */
194 return ssh_get_next_identity(auth, e, n, comment);
198 * Returns the next authentication identity for the agent. Other functions
199 * can be called between this and ssh_get_first_identity or two calls of this
200 * function. This returns 0 if there are no more identities. The caller
201 * must free comment after a successful return.
205 ssh_get_next_identity(AuthenticationConnection *auth,
206 BIGNUM *e, BIGNUM *n, char **comment)
210 /* Return failure if no more entries. */
211 if (auth->howmany <= 0)
215 * Get the next entry from the packet. These will abort with a fatal
216 * error if the packet is too short or contains corrupt data.
218 bits = buffer_get_int(&auth->identities);
219 buffer_get_bignum(&auth->identities, e);
220 buffer_get_bignum(&auth->identities, n);
221 *comment = buffer_get_string(&auth->identities, NULL);
223 if (bits != BN_num_bits(n))
224 log("Warning: identity keysize mismatch: actual %d, announced %u",
225 BN_num_bits(n), bits);
227 /* Decrement the number of remaining entries. */
234 * Generates a random challenge, sends it to the agent, and waits for
235 * response from the agent. Returns true (non-zero) if the agent gave the
236 * correct answer, zero otherwise. Response type selects the style of
237 * response desired, with 0 corresponding to protocol version 1.0 (no longer
238 * supported) and 1 corresponding to protocol version 1.1.
242 ssh_decrypt_challenge(AuthenticationConnection *auth,
243 BIGNUM* e, BIGNUM *n, BIGNUM *challenge,
244 unsigned char session_id[16],
245 unsigned int response_type,
246 unsigned char response[16])
249 unsigned char buf[8192];
252 /* Response type 0 is no longer supported. */
253 if (response_type == 0)
254 fatal("Compatibility with ssh protocol version 1.0 no longer supported.");
256 /* Format a message to the agent. */
257 buf[0] = SSH_AGENTC_RSA_CHALLENGE;
258 buffer_init(&buffer);
259 buffer_append(&buffer, (char *) buf, 1);
260 buffer_put_int(&buffer, BN_num_bits(n));
261 buffer_put_bignum(&buffer, e);
262 buffer_put_bignum(&buffer, n);
263 buffer_put_bignum(&buffer, challenge);
264 buffer_append(&buffer, (char *) session_id, 16);
265 buffer_put_int(&buffer, response_type);
267 /* Get the length of the message, and format it in the buffer. */
268 len = buffer_len(&buffer);
271 /* Send the length and then the packet to the agent. */
272 if (atomicio(write, auth->fd, buf, 4) != 4 ||
273 atomicio(write, auth->fd, buffer_ptr(&buffer),
274 buffer_len(&buffer)) != buffer_len(&buffer)) {
275 error("Error writing to authentication socket.");
277 buffer_free(&buffer);
281 * Wait for response from the agent. First read the length of the
286 l = read(auth->fd, buf + 4 - len, len);
288 error("Error reading response length from authentication socket.");
294 /* Extract the length, and check it for sanity. */
295 len = GET_32BIT(buf);
296 if (len > 256 * 1024)
297 fatal("Authentication response too long: %d", len);
299 /* Read the rest of the response in tothe buffer. */
300 buffer_clear(&buffer);
305 l = read(auth->fd, buf, l);
307 error("Error reading response from authentication socket.");
310 buffer_append(&buffer, (char *) buf, l);
314 /* Get the type of the packet. */
315 buffer_get(&buffer, (char *) buf, 1);
317 /* Check for agent failure message. */
318 if (buf[0] == SSH_AGENT_FAILURE) {
319 log("Agent admitted failure to authenticate using the key.");
322 /* Now it must be an authentication response packet. */
323 if (buf[0] != SSH_AGENT_RSA_RESPONSE)
324 fatal("Bad authentication response: %d", buf[0]);
327 * Get the response from the packet. This will abort with a fatal
328 * error if the packet is corrupt.
330 for (i = 0; i < 16; i++)
331 response[i] = buffer_get_char(&buffer);
333 /* The buffer containing the packet is no longer needed. */
334 buffer_free(&buffer);
336 /* Correct answer. */
340 /* Encode key for a message to the agent. */
343 ssh_encode_identity_rsa(Buffer *b, RSA *key, const char *comment)
346 buffer_put_char(b, SSH_AGENTC_ADD_RSA_IDENTITY);
347 buffer_put_int(b, BN_num_bits(key->n));
348 buffer_put_bignum(b, key->n);
349 buffer_put_bignum(b, key->e);
350 buffer_put_bignum(b, key->d);
351 /* To keep within the protocol: p < q for ssh. in SSL p > q */
352 buffer_put_bignum(b, key->iqmp); /* ssh key->u */
353 buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */
354 buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */
355 buffer_put_string(b, comment, strlen(comment));
359 ssh_encode_identity_dsa(Buffer *b, DSA *key, const char *comment)
362 buffer_put_char(b, SSH2_AGENTC_ADD_IDENTITY);
363 buffer_put_cstring(b, KEX_DSS);
364 buffer_put_bignum2(b, key->p);
365 buffer_put_bignum2(b, key->q);
366 buffer_put_bignum2(b, key->g);
367 buffer_put_bignum2(b, key->pub_key);
368 buffer_put_bignum2(b, key->priv_key);
369 buffer_put_string(b, comment, strlen(comment));
373 * Adds an identity to the authentication server. This call is not meant to
374 * be used by normal applications.
378 ssh_add_identity(AuthenticationConnection *auth, Key *key, const char *comment)
381 unsigned char buf[8192];
384 buffer_init(&buffer);
388 ssh_encode_identity_rsa(&buffer, key->rsa, comment);
391 ssh_encode_identity_dsa(&buffer, key->dsa, comment);
394 buffer_free(&buffer);
399 /* Get the length of the message, and format it in the buffer. */
400 len = buffer_len(&buffer);
403 /* Send the length and then the packet to the agent. */
404 if (atomicio(write, auth->fd, buf, 4) != 4 ||
405 atomicio(write, auth->fd, buffer_ptr(&buffer),
406 buffer_len(&buffer)) != buffer_len(&buffer)) {
407 error("Error writing to authentication socket.");
408 buffer_free(&buffer);
411 buffer_free(&buffer);
412 return ssh_agent_get_reply(auth);
416 * Removes an identity from the authentication server. This call is not
417 * meant to be used by normal applications.
421 ssh_remove_identity(AuthenticationConnection *auth, RSA *key)
424 unsigned char buf[5];
427 /* Format a message to the agent. */
428 buffer_init(&buffer);
429 buffer_put_char(&buffer, SSH_AGENTC_REMOVE_RSA_IDENTITY);
430 buffer_put_int(&buffer, BN_num_bits(key->n));
431 buffer_put_bignum(&buffer, key->e);
432 buffer_put_bignum(&buffer, key->n);
434 /* Get the length of the message, and format it in the buffer. */
435 len = buffer_len(&buffer);
438 /* Send the length and then the packet to the agent. */
439 if (atomicio(write, auth->fd, buf, 4) != 4 ||
440 atomicio(write, auth->fd, buffer_ptr(&buffer),
441 buffer_len(&buffer)) != buffer_len(&buffer)) {
442 error("Error writing to authentication socket.");
443 buffer_free(&buffer);
446 buffer_free(&buffer);
447 return ssh_agent_get_reply(auth);
451 * Removes all identities from the agent. This call is not meant to be used
452 * by normal applications.
456 ssh_remove_all_identities(AuthenticationConnection *auth)
458 unsigned char buf[5];
460 /* Get the length of the message, and format it in the buffer. */
462 buf[4] = SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES;
464 /* Send the length and then the packet to the agent. */
465 if (atomicio(write, auth->fd, buf, 5) != 5) {
466 error("Error writing to authentication socket.");
469 return ssh_agent_get_reply(auth);
473 * Read for reply from agent. returns 1 for success, 0 on error
477 ssh_agent_get_reply(AuthenticationConnection *auth)
480 unsigned char buf[8192];
484 * Wait for response from the agent. First read the length of the
489 l = read(auth->fd, buf + 4 - len, len);
491 error("Error reading response length from authentication socket.");
492 buffer_free(&buffer);
498 /* Extract the length, and check it for sanity. */
499 len = GET_32BIT(buf);
500 if (len > 256 * 1024)
501 fatal("Response from agent too long: %d", len);
503 /* Read the rest of the response in to the buffer. */
504 buffer_init(&buffer);
509 l = read(auth->fd, buf, l);
511 error("Error reading response from authentication socket.");
512 buffer_free(&buffer);
515 buffer_append(&buffer, (char *) buf, l);
519 /* Get the type of the packet. */
520 type = buffer_get_char(&buffer);
521 buffer_free(&buffer);
523 case SSH_AGENT_FAILURE:
524 log("SSH_AGENT_FAILURE");
526 case SSH_AGENT_SUCCESS:
529 fatal("Bad response from authentication agent: %d", type);