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 1.21 2000/06/26 09:22:29 markus Exp $");
27 #include <openssl/rsa.h>
30 int ssh_agent_get_reply(AuthenticationConnection *auth);
32 /* Returns the number of the authentication fd, or -1 if there is none. */
35 ssh_get_authentication_socket()
37 const char *authsocket;
39 struct sockaddr_un sunaddr;
41 authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
45 sunaddr.sun_family = AF_UNIX;
46 strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
48 sock = socket(AF_UNIX, SOCK_STREAM, 0);
53 if (fcntl(sock, F_SETFD, 1) == -1) {
57 if (connect(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
65 * Closes the agent socket if it should be closed (depends on how it was
66 * obtained). The argument must have been returned by
67 * ssh_get_authentication_socket().
71 ssh_close_authentication_socket(int sock)
73 if (getenv(SSH_AUTHSOCKET_ENV_NAME))
78 * Opens and connects a private socket for communication with the
79 * authentication agent. Returns the file descriptor (which must be
80 * shut down and closed by the caller when no longer needed).
81 * Returns NULL if an error occurred and the connection could not be
85 AuthenticationConnection *
86 ssh_get_authentication_connection()
88 AuthenticationConnection *auth;
91 sock = ssh_get_authentication_socket();
94 * Fail if we couldn't obtain a connection. This happens if we
95 * exited due to a timeout.
100 auth = xmalloc(sizeof(*auth));
102 buffer_init(&auth->packet);
103 buffer_init(&auth->identities);
110 * Closes the connection to the authentication agent and frees any associated
115 ssh_close_authentication_connection(AuthenticationConnection *ac)
117 buffer_free(&ac->packet);
118 buffer_free(&ac->identities);
124 * Returns the first authentication identity held by the agent.
125 * Returns true if an identity is available, 0 otherwise.
126 * The caller must initialize the integers before the call, and free the
127 * comment after a successful call (before calling ssh_get_next_identity).
131 ssh_get_first_identity(AuthenticationConnection *auth,
132 BIGNUM *e, BIGNUM *n, char **comment)
134 unsigned char msg[8192];
138 * Send a message to the agent requesting for a list of the
139 * identities it can represent.
145 msg[4] = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
146 if (atomicio(write, auth->fd, msg, 5) != 5) {
147 error("write auth->fd: %.100s", strerror(errno));
150 /* Read the length of the response. XXX implement timeouts here. */
153 l = read(auth->fd, msg + 4 - len, len);
155 error("read auth->fd: %.100s", strerror(errno));
162 * Extract the length, and check it for sanity. (We cannot trust
163 * authentication agents).
165 len = GET_32BIT(msg);
166 if (len < 1 || len > 256 * 1024)
167 fatal("Authentication reply message too long: %d\n", len);
169 /* Read the packet itself. */
170 buffer_clear(&auth->identities);
175 l = read(auth->fd, msg, l);
177 fatal("Incomplete authentication reply.");
178 buffer_append(&auth->identities, (char *) msg, l);
182 /* Get message type, and verify that we got a proper answer. */
183 buffer_get(&auth->identities, (char *) msg, 1);
184 if (msg[0] != SSH_AGENT_RSA_IDENTITIES_ANSWER)
185 fatal("Bad authentication reply message type: %d", msg[0]);
187 /* Get the number of entries in the response and check it for sanity. */
188 auth->howmany = buffer_get_int(&auth->identities);
189 if (auth->howmany > 1024)
190 fatal("Too many identities in authentication reply: %d\n", auth->howmany);
192 /* Return the first entry (if any). */
193 return ssh_get_next_identity(auth, e, n, comment);
197 * Returns the next authentication identity for the agent. Other functions
198 * can be called between this and ssh_get_first_identity or two calls of this
199 * function. This returns 0 if there are no more identities. The caller
200 * must free comment after a successful return.
204 ssh_get_next_identity(AuthenticationConnection *auth,
205 BIGNUM *e, BIGNUM *n, char **comment)
209 /* Return failure if no more entries. */
210 if (auth->howmany <= 0)
214 * Get the next entry from the packet. These will abort with a fatal
215 * error if the packet is too short or contains corrupt data.
217 bits = buffer_get_int(&auth->identities);
218 buffer_get_bignum(&auth->identities, e);
219 buffer_get_bignum(&auth->identities, n);
220 *comment = buffer_get_string(&auth->identities, NULL);
222 if (bits != BN_num_bits(n))
223 log("Warning: identity keysize mismatch: actual %d, announced %u",
224 BN_num_bits(n), bits);
226 /* Decrement the number of remaining entries. */
233 * Generates a random challenge, sends it to the agent, and waits for
234 * response from the agent. Returns true (non-zero) if the agent gave the
235 * correct answer, zero otherwise. Response type selects the style of
236 * response desired, with 0 corresponding to protocol version 1.0 (no longer
237 * supported) and 1 corresponding to protocol version 1.1.
241 ssh_decrypt_challenge(AuthenticationConnection *auth,
242 BIGNUM* e, BIGNUM *n, BIGNUM *challenge,
243 unsigned char session_id[16],
244 unsigned int response_type,
245 unsigned char response[16])
248 unsigned char buf[8192];
251 /* Response type 0 is no longer supported. */
252 if (response_type == 0)
253 fatal("Compatibility with ssh protocol version 1.0 no longer supported.");
255 /* Format a message to the agent. */
256 buf[0] = SSH_AGENTC_RSA_CHALLENGE;
257 buffer_init(&buffer);
258 buffer_append(&buffer, (char *) buf, 1);
259 buffer_put_int(&buffer, BN_num_bits(n));
260 buffer_put_bignum(&buffer, e);
261 buffer_put_bignum(&buffer, n);
262 buffer_put_bignum(&buffer, challenge);
263 buffer_append(&buffer, (char *) session_id, 16);
264 buffer_put_int(&buffer, response_type);
266 /* Get the length of the message, and format it in the buffer. */
267 len = buffer_len(&buffer);
270 /* Send the length and then the packet to the agent. */
271 if (atomicio(write, auth->fd, buf, 4) != 4 ||
272 atomicio(write, auth->fd, buffer_ptr(&buffer),
273 buffer_len(&buffer)) != buffer_len(&buffer)) {
274 error("Error writing to authentication socket.");
276 buffer_free(&buffer);
280 * Wait for response from the agent. First read the length of the
285 l = read(auth->fd, buf + 4 - len, len);
287 error("Error reading response length from authentication socket.");
293 /* Extract the length, and check it for sanity. */
294 len = GET_32BIT(buf);
295 if (len > 256 * 1024)
296 fatal("Authentication response too long: %d", len);
298 /* Read the rest of the response in tothe buffer. */
299 buffer_clear(&buffer);
304 l = read(auth->fd, buf, l);
306 error("Error reading response from authentication socket.");
309 buffer_append(&buffer, (char *) buf, l);
313 /* Get the type of the packet. */
314 buffer_get(&buffer, (char *) buf, 1);
316 /* Check for agent failure message. */
317 if (buf[0] == SSH_AGENT_FAILURE) {
318 log("Agent admitted failure to authenticate using the key.");
321 /* Now it must be an authentication response packet. */
322 if (buf[0] != SSH_AGENT_RSA_RESPONSE)
323 fatal("Bad authentication response: %d", buf[0]);
326 * Get the response from the packet. This will abort with a fatal
327 * error if the packet is corrupt.
329 for (i = 0; i < 16; i++)
330 response[i] = buffer_get_char(&buffer);
332 /* The buffer containing the packet is no longer needed. */
333 buffer_free(&buffer);
335 /* Correct answer. */
340 * Adds an identity to the authentication server. This call is not meant to
341 * be used by normal applications.
345 ssh_add_identity(AuthenticationConnection *auth,
346 RSA * key, const char *comment)
349 unsigned char buf[8192];
352 /* Format a message to the agent. */
353 buffer_init(&buffer);
354 buffer_put_char(&buffer, SSH_AGENTC_ADD_RSA_IDENTITY);
355 buffer_put_int(&buffer, BN_num_bits(key->n));
356 buffer_put_bignum(&buffer, key->n);
357 buffer_put_bignum(&buffer, key->e);
358 buffer_put_bignum(&buffer, key->d);
359 /* To keep within the protocol: p < q for ssh. in SSL p > q */
360 buffer_put_bignum(&buffer, key->iqmp); /* ssh key->u */
361 buffer_put_bignum(&buffer, key->q); /* ssh key->p, SSL key->q */
362 buffer_put_bignum(&buffer, key->p); /* ssh key->q, SSL key->p */
363 buffer_put_string(&buffer, comment, strlen(comment));
365 /* Get the length of the message, and format it in the buffer. */
366 len = buffer_len(&buffer);
369 /* Send the length and then the packet to the agent. */
370 if (atomicio(write, auth->fd, buf, 4) != 4 ||
371 atomicio(write, auth->fd, buffer_ptr(&buffer),
372 buffer_len(&buffer)) != buffer_len(&buffer)) {
373 error("Error writing to authentication socket.");
374 buffer_free(&buffer);
377 buffer_free(&buffer);
378 return ssh_agent_get_reply(auth);
382 * Removes an identity from the authentication server. This call is not
383 * meant to be used by normal applications.
387 ssh_remove_identity(AuthenticationConnection *auth, RSA *key)
390 unsigned char buf[5];
393 /* Format a message to the agent. */
394 buffer_init(&buffer);
395 buffer_put_char(&buffer, SSH_AGENTC_REMOVE_RSA_IDENTITY);
396 buffer_put_int(&buffer, BN_num_bits(key->n));
397 buffer_put_bignum(&buffer, key->e);
398 buffer_put_bignum(&buffer, key->n);
400 /* Get the length of the message, and format it in the buffer. */
401 len = buffer_len(&buffer);
404 /* Send the length and then the packet to the agent. */
405 if (atomicio(write, auth->fd, buf, 4) != 4 ||
406 atomicio(write, auth->fd, buffer_ptr(&buffer),
407 buffer_len(&buffer)) != buffer_len(&buffer)) {
408 error("Error writing to authentication socket.");
409 buffer_free(&buffer);
412 buffer_free(&buffer);
413 return ssh_agent_get_reply(auth);
417 * Removes all identities from the agent. This call is not meant to be used
418 * by normal applications.
422 ssh_remove_all_identities(AuthenticationConnection *auth)
424 unsigned char buf[5];
426 /* Get the length of the message, and format it in the buffer. */
428 buf[4] = SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES;
430 /* Send the length and then the packet to the agent. */
431 if (atomicio(write, auth->fd, buf, 5) != 5) {
432 error("Error writing to authentication socket.");
435 return ssh_agent_get_reply(auth);
439 * Read for reply from agent. returns 1 for success, 0 on error
443 ssh_agent_get_reply(AuthenticationConnection *auth)
446 unsigned char buf[8192];
450 * Wait for response from the agent. First read the length of the
455 l = read(auth->fd, buf + 4 - len, len);
457 error("Error reading response length from authentication socket.");
458 buffer_free(&buffer);
464 /* Extract the length, and check it for sanity. */
465 len = GET_32BIT(buf);
466 if (len > 256 * 1024)
467 fatal("Response from agent too long: %d", len);
469 /* Read the rest of the response in to the buffer. */
470 buffer_init(&buffer);
475 l = read(auth->fd, buf, l);
477 error("Error reading response from authentication socket.");
478 buffer_free(&buffer);
481 buffer_append(&buffer, (char *) buf, l);
485 /* Get the type of the packet. */
486 type = buffer_get_char(&buffer);
487 buffer_free(&buffer);
489 case SSH_AGENT_FAILURE:
491 case SSH_AGENT_SUCCESS:
494 fatal("Bad response from authentication agent: %d", type);