1 /* $OpenBSD: ssh-agent.c,v 1.49 2001/01/29 19:47:31 markus Exp $ */
4 * Author: Tatu Ylonen <ylo@cs.hut.fi>
5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
7 * The authentication agent program.
9 * As far as I am concerned, the code I have written for this software
10 * can be used freely for any purpose. Any derived versions of this
11 * software must be clearly marked as such, and if the derived work is
12 * incompatible with the protocol description in the RFC file, it must be
13 * called by a name other than "ssh" or "Secure Shell".
15 * SSH2 implementation,
16 * Copyright (c) 2000 Markus Friedl. All rights reserved.
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions
21 * 1. Redistributions of source code must retain the above copyright
22 * notice, this list of conditions and the following disclaimer.
23 * 2. Redistributions in binary form must reproduce the above copyright
24 * notice, this list of conditions and the following disclaimer in the
25 * documentation and/or other materials provided with the distribution.
27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
40 RCSID("$OpenBSD: ssh-agent.c,v 1.49 2001/01/29 19:47:31 markus Exp $");
42 #include <openssl/evp.h>
43 #include <openssl/md5.h>
63 AUTH_UNUSED, AUTH_SOCKET, AUTH_CONNECTION
69 u_int sockets_alloc = 0;
70 SocketEntry *sockets = NULL;
82 /* private key table, one per protocol version */
87 /* pid of shell == parent of agent */
88 pid_t parent_pid = -1;
90 /* pathname and directory for AUTH_SOCKET */
91 char socket_name[1024];
92 char socket_dir[1024];
94 #ifdef HAVE___PROGNAME
95 extern char *__progname;
100 int prepare_select(fd_set **, fd_set **, int *);
106 for (i = 0; i <=2; i++){
107 idtable[i].identities = NULL;
108 idtable[i].nentries = 0;
112 /* return private key table for requested protocol version */
114 idtab_lookup(int version)
116 if (version < 1 || version > 2)
117 fatal("internal error, bad protocol version %d", version);
118 return &idtable[version];
121 /* return matching private key for given public key */
123 lookup_private_key(Key *key, int *idx, int version)
126 Idtab *tab = idtab_lookup(version);
127 for (i = 0; i < tab->nentries; i++) {
128 if (key_equal(key, tab->identities[i].key)) {
131 return tab->identities[i].key;
137 /* send list of supported public keys to 'client' */
139 process_request_identities(SocketEntry *e, int version)
141 Idtab *tab = idtab_lookup(version);
146 buffer_put_char(&msg, (version == 1) ?
147 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
148 buffer_put_int(&msg, tab->nentries);
149 for (i = 0; i < tab->nentries; i++) {
150 Identity *id = &tab->identities[i];
151 if (id->key->type == KEY_RSA1) {
152 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
153 buffer_put_bignum(&msg, id->key->rsa->e);
154 buffer_put_bignum(&msg, id->key->rsa->n);
158 key_to_blob(id->key, &blob, &blen);
159 buffer_put_string(&msg, blob, blen);
162 buffer_put_cstring(&msg, id->comment);
164 buffer_put_int(&e->output, buffer_len(&msg));
165 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
171 process_authentication_challenge1(SocketEntry *e)
178 u_char buf[32], mdbuf[16], session_id[16];
182 key = key_new(KEY_RSA1);
183 challenge = BN_new();
185 buffer_get_int(&e->input); /* ignored */
186 buffer_get_bignum(&e->input, key->rsa->e);
187 buffer_get_bignum(&e->input, key->rsa->n);
188 buffer_get_bignum(&e->input, challenge);
190 /* Only protocol 1.1 is supported */
191 if (buffer_len(&e->input) == 0)
193 buffer_get(&e->input, (char *) session_id, 16);
194 response_type = buffer_get_int(&e->input);
195 if (response_type != 1)
198 private = lookup_private_key(key, NULL, 1);
199 if (private != NULL) {
200 /* Decrypt the challenge using the private key. */
201 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
204 /* The response is MD5 of decrypted challenge plus session id. */
205 len = BN_num_bytes(challenge);
206 if (len <= 0 || len > 32) {
207 log("process_authentication_challenge: bad challenge length %d", len);
211 BN_bn2bin(challenge, buf + 32 - len);
213 MD5_Update(&md, buf, 32);
214 MD5_Update(&md, session_id, 16);
215 MD5_Final(mdbuf, &md);
217 /* Send the response. */
218 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
219 for (i = 0; i < 16; i++)
220 buffer_put_char(&msg, mdbuf[i]);
225 /* Unknown identity or protocol error. Send failure. */
226 buffer_put_char(&msg, SSH_AGENT_FAILURE);
228 buffer_put_int(&e->output, buffer_len(&msg));
229 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
231 BN_clear_free(challenge);
237 process_sign_request2(SocketEntry *e)
239 extern int datafellows;
241 u_char *blob, *data, *signature = NULL;
242 u_int blen, dlen, slen = 0;
249 blob = buffer_get_string(&e->input, &blen);
250 data = buffer_get_string(&e->input, &dlen);
252 flags = buffer_get_int(&e->input);
253 if (flags & SSH_AGENT_OLD_SIGNATURE)
254 datafellows = SSH_BUG_SIGBLOB;
256 key = key_from_blob(blob, blen);
258 private = lookup_private_key(key, NULL, 2);
260 ok = key_sign(private, &signature, &slen, data, dlen);
265 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
266 buffer_put_string(&msg, signature, slen);
268 buffer_put_char(&msg, SSH_AGENT_FAILURE);
270 buffer_put_int(&e->output, buffer_len(&msg));
271 buffer_append(&e->output, buffer_ptr(&msg),
276 if (signature != NULL)
282 process_remove_identity(SocketEntry *e, int version)
284 Key *key = NULL, *private;
292 key = key_new(KEY_RSA1);
293 bits = buffer_get_int(&e->input);
294 buffer_get_bignum(&e->input, key->rsa->e);
295 buffer_get_bignum(&e->input, key->rsa->n);
297 if (bits != key_size(key))
298 log("Warning: identity keysize mismatch: actual %d, announced %d",
299 key_size(key), bits);
302 blob = buffer_get_string(&e->input, &blen);
303 key = key_from_blob(blob, blen);
309 private = lookup_private_key(key, &idx, version);
310 if (private != NULL) {
312 * We have this key. Free the old key. Since we
313 * don\'t want to leave empty slots in the middle of
314 * the array, we actually free the key there and move
315 * all the entries between the empty slot and the end
318 Idtab *tab = idtab_lookup(version);
319 key_free(tab->identities[idx].key);
320 xfree(tab->identities[idx].comment);
321 if (tab->nentries < 1)
322 fatal("process_remove_identity: "
323 "internal error: tab->nentries %d",
325 if (idx != tab->nentries - 1) {
327 for (i = idx; i < tab->nentries - 1; i++)
328 tab->identities[i] = tab->identities[i+1];
330 tab->identities[tab->nentries - 1].key = NULL;
331 tab->identities[tab->nentries - 1].comment = NULL;
337 buffer_put_int(&e->output, 1);
338 buffer_put_char(&e->output,
339 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
343 process_remove_all_identities(SocketEntry *e, int version)
346 Idtab *tab = idtab_lookup(version);
348 /* Loop over all identities and clear the keys. */
349 for (i = 0; i < tab->nentries; i++) {
350 key_free(tab->identities[i].key);
351 xfree(tab->identities[i].comment);
354 /* Mark that there are no identities. */
358 buffer_put_int(&e->output, 1);
359 buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
364 generate_additional_parameters(RSA *rsa)
368 /* Generate additional parameters */
372 BN_sub(aux, rsa->q, BN_value_one());
373 BN_mod(rsa->dmq1, rsa->d, aux, ctx);
375 BN_sub(aux, rsa->p, BN_value_one());
376 BN_mod(rsa->dmp1, rsa->d, aux, ctx);
383 process_add_identity(SocketEntry *e, int version)
388 int type, success = 0;
389 Idtab *tab = idtab_lookup(version);
393 k = key_new_private(KEY_RSA1);
394 buffer_get_int(&e->input); /* ignored */
395 buffer_get_bignum(&e->input, k->rsa->n);
396 buffer_get_bignum(&e->input, k->rsa->e);
397 buffer_get_bignum(&e->input, k->rsa->d);
398 buffer_get_bignum(&e->input, k->rsa->iqmp);
400 /* SSH and SSL have p and q swapped */
401 buffer_get_bignum(&e->input, k->rsa->q); /* p */
402 buffer_get_bignum(&e->input, k->rsa->p); /* q */
404 /* Generate additional parameters */
405 generate_additional_parameters(k->rsa);
408 type_name = buffer_get_string(&e->input, NULL);
409 type = key_type_from_name(type_name);
413 k = key_new_private(type);
414 buffer_get_bignum2(&e->input, k->dsa->p);
415 buffer_get_bignum2(&e->input, k->dsa->q);
416 buffer_get_bignum2(&e->input, k->dsa->g);
417 buffer_get_bignum2(&e->input, k->dsa->pub_key);
418 buffer_get_bignum2(&e->input, k->dsa->priv_key);
421 k = key_new_private(type);
422 buffer_get_bignum2(&e->input, k->rsa->n);
423 buffer_get_bignum2(&e->input, k->rsa->e);
424 buffer_get_bignum2(&e->input, k->rsa->d);
425 buffer_get_bignum2(&e->input, k->rsa->iqmp);
426 buffer_get_bignum2(&e->input, k->rsa->p);
427 buffer_get_bignum2(&e->input, k->rsa->q);
429 /* Generate additional parameters */
430 generate_additional_parameters(k->rsa);
433 buffer_clear(&e->input);
438 comment = buffer_get_string(&e->input, NULL);
444 if (lookup_private_key(k, NULL, version) == NULL) {
445 if (tab->nentries == 0)
446 tab->identities = xmalloc(sizeof(Identity));
448 tab->identities = xrealloc(tab->identities,
449 (tab->nentries + 1) * sizeof(Identity));
450 tab->identities[tab->nentries].key = k;
451 tab->identities[tab->nentries].comment = comment;
452 /* Increment the number of identities. */
459 buffer_put_int(&e->output, 1);
460 buffer_put_char(&e->output,
461 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
464 /* dispatch incoming messages */
467 process_message(SocketEntry *e)
472 if (buffer_len(&e->input) < 5)
473 return; /* Incomplete message. */
474 cp = (u_char *) buffer_ptr(&e->input);
475 msg_len = GET_32BIT(cp);
476 if (msg_len > 256 * 1024) {
477 shutdown(e->fd, SHUT_RDWR);
479 e->type = AUTH_UNUSED;
482 if (buffer_len(&e->input) < msg_len + 4)
484 buffer_consume(&e->input, 4);
485 type = buffer_get_char(&e->input);
489 case SSH_AGENTC_RSA_CHALLENGE:
490 process_authentication_challenge1(e);
492 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
493 process_request_identities(e, 1);
495 case SSH_AGENTC_ADD_RSA_IDENTITY:
496 process_add_identity(e, 1);
498 case SSH_AGENTC_REMOVE_RSA_IDENTITY:
499 process_remove_identity(e, 1);
501 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
502 process_remove_all_identities(e, 1);
505 case SSH2_AGENTC_SIGN_REQUEST:
506 process_sign_request2(e);
508 case SSH2_AGENTC_REQUEST_IDENTITIES:
509 process_request_identities(e, 2);
511 case SSH2_AGENTC_ADD_IDENTITY:
512 process_add_identity(e, 2);
514 case SSH2_AGENTC_REMOVE_IDENTITY:
515 process_remove_identity(e, 2);
517 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
518 process_remove_all_identities(e, 2);
521 /* Unknown message. Respond with failure. */
522 error("Unknown message %d", type);
523 buffer_clear(&e->input);
524 buffer_put_int(&e->output, 1);
525 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
531 new_socket(int type, int fd)
534 if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
535 error("fcntl O_NONBLOCK: %s", strerror(errno));
540 for (i = 0; i < sockets_alloc; i++)
541 if (sockets[i].type == AUTH_UNUSED) {
543 sockets[i].type = type;
544 buffer_init(&sockets[i].input);
545 buffer_init(&sockets[i].output);
548 old_alloc = sockets_alloc;
551 sockets = xrealloc(sockets, sockets_alloc * sizeof(sockets[0]));
553 sockets = xmalloc(sockets_alloc * sizeof(sockets[0]));
554 for (i = old_alloc; i < sockets_alloc; i++)
555 sockets[i].type = AUTH_UNUSED;
556 sockets[old_alloc].type = type;
557 sockets[old_alloc].fd = fd;
558 buffer_init(&sockets[old_alloc].input);
559 buffer_init(&sockets[old_alloc].output);
563 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl)
568 for (i = 0; i < sockets_alloc; i++) {
569 switch (sockets[i].type) {
571 case AUTH_CONNECTION:
572 n = MAX(n, sockets[i].fd);
577 fatal("Unknown socket type %d", sockets[i].type);
582 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
583 if (*fdrp == NULL || n > *fdl) {
592 memset(*fdrp, 0, sz);
593 memset(*fdwp, 0, sz);
595 for (i = 0; i < sockets_alloc; i++) {
596 switch (sockets[i].type) {
598 case AUTH_CONNECTION:
599 FD_SET(sockets[i].fd, *fdrp);
600 if (buffer_len(&sockets[i].output) > 0)
601 FD_SET(sockets[i].fd, *fdwp);
611 after_select(fd_set *readset, fd_set *writeset)
617 struct sockaddr_un sunaddr;
619 for (i = 0; i < sockets_alloc; i++)
620 switch (sockets[i].type) {
624 if (FD_ISSET(sockets[i].fd, readset)) {
625 slen = sizeof(sunaddr);
626 sock = accept(sockets[i].fd,
627 (struct sockaddr *) &sunaddr, &slen);
629 perror("accept from AUTH_SOCKET");
632 new_socket(AUTH_CONNECTION, sock);
635 case AUTH_CONNECTION:
636 if (buffer_len(&sockets[i].output) > 0 &&
637 FD_ISSET(sockets[i].fd, writeset)) {
638 len = write(sockets[i].fd,
639 buffer_ptr(&sockets[i].output),
640 buffer_len(&sockets[i].output));
642 shutdown(sockets[i].fd, SHUT_RDWR);
643 close(sockets[i].fd);
644 sockets[i].type = AUTH_UNUSED;
645 buffer_free(&sockets[i].input);
646 buffer_free(&sockets[i].output);
649 buffer_consume(&sockets[i].output, len);
651 if (FD_ISSET(sockets[i].fd, readset)) {
652 len = read(sockets[i].fd, buf, sizeof(buf));
654 shutdown(sockets[i].fd, SHUT_RDWR);
655 close(sockets[i].fd);
656 sockets[i].type = AUTH_UNUSED;
657 buffer_free(&sockets[i].input);
658 buffer_free(&sockets[i].output);
661 buffer_append(&sockets[i].input, buf, len);
662 process_message(&sockets[i]);
666 fatal("Unknown type %d", sockets[i].type);
671 check_parent_exists(int sig)
673 int save_errno = errno;
675 if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
676 /* printf("Parent has died - Authentication agent exiting.\n"); */
679 signal(SIGALRM, check_parent_exists);
701 cleanup_handler(int sig)
710 fprintf(stderr, "ssh-agent version %s\n", SSH_VERSION);
711 fprintf(stderr, "Usage: %s [-c | -s] [-k] [command {args...]]\n",
717 main(int ac, char **av)
719 int sock, c_flag = 0, k_flag = 0, s_flag = 0, ch;
720 struct sockaddr_un sunaddr;
721 #ifdef HAVE_SETRLIMIT
725 char *shell, *format, *pidstr, pidstrbuf[1 + 3 * sizeof pid];
727 fd_set *readsetp = NULL, *writesetp = NULL;
729 __progname = get_progname(av[0]);
732 #ifdef __GNU_LIBRARY__
733 while ((ch = getopt(ac, av, "+cks")) != -1) {
734 #else /* __GNU_LIBRARY__ */
735 while ((ch = getopt(ac, av, "cks")) != -1) {
736 #endif /* __GNU_LIBRARY__ */
758 if (ac > 0 && (c_flag || k_flag || s_flag))
761 if (ac == 0 && !c_flag && !k_flag && !s_flag) {
762 shell = getenv("SHELL");
763 if (shell != NULL && strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
767 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
768 if (pidstr == NULL) {
769 fprintf(stderr, "%s not set, cannot kill agent\n",
770 SSH_AGENTPID_ENV_NAME);
775 fprintf(stderr, "%s=\"%s\", which is not a good PID\n",
776 SSH_AGENTPID_ENV_NAME, pidstr);
779 if (kill(pid, SIGTERM) == -1) {
783 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
784 printf(format, SSH_AUTHSOCKET_ENV_NAME);
785 printf(format, SSH_AGENTPID_ENV_NAME);
786 printf("echo Agent pid %d killed;\n", pid);
789 parent_pid = getpid();
791 /* Create private directory for agent socket */
792 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXX", sizeof socket_dir);
793 if (mkdtemp(socket_dir) == NULL) {
794 perror("mkdtemp: private socket dir");
797 snprintf(socket_name, sizeof socket_name, "%s/agent.%d", socket_dir,
801 * Create socket early so it will exist before command gets run from
804 sock = socket(AF_UNIX, SOCK_STREAM, 0);
809 memset(&sunaddr, 0, sizeof(sunaddr));
810 sunaddr.sun_family = AF_UNIX;
811 strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
812 if (bind(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) {
816 if (listen(sock, 5) < 0) {
822 * Fork, and have the parent execute the command, if any, or present
823 * the socket data. The child continues as the authentication agent.
830 if (pid != 0) { /* Parent - execute the given command. */
832 snprintf(pidstrbuf, sizeof pidstrbuf, "%d", pid);
834 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
835 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
836 SSH_AUTHSOCKET_ENV_NAME);
837 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
838 SSH_AGENTPID_ENV_NAME);
839 printf("echo Agent pid %d;\n", pid);
842 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
843 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
855 #ifdef HAVE_SETRLIMIT
856 /* deny core dumps, since memory contains unencrypted private keys */
857 rlim.rlim_cur = rlim.rlim_max = 0;
858 if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
859 perror("setrlimit rlimit_core failed");
863 if (setsid() == -1) {
867 if (atexit(cleanup_socket) < 0) {
871 new_socket(AUTH_SOCKET, sock);
873 signal(SIGALRM, check_parent_exists);
877 signal(SIGINT, SIG_IGN);
878 signal(SIGPIPE, SIG_IGN);
879 signal(SIGHUP, cleanup_handler);
880 signal(SIGTERM, cleanup_handler);
882 prepare_select(&readsetp, &writesetp, &max_fd);
883 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
888 after_select(readsetp, writesetp);