1/* $OpenBSD: ssh-add.c,v 1.136 2018/09/19 02:03:02 djm Exp $ */
2/*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 *                    All rights reserved
6 * Adds an identity to the authentication server, or removes an identity.
7 *
8 * As far as I am concerned, the code I have written for this software
9 * can be used freely for any purpose.  Any derived versions of this
10 * software must be clearly marked as such, and if the derived work is
11 * incompatible with the protocol description in the RFC file, it must be
12 * called by a name other than "ssh" or "Secure Shell".
13 *
14 * SSH2 implementation,
15 * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
16 *
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
19 * are met:
20 * 1. Redistributions of source code must retain the above copyright
21 *    notice, this list of conditions and the following disclaimer.
22 * 2. Redistributions in binary form must reproduce the above copyright
23 *    notice, this list of conditions and the following disclaimer in the
24 *    documentation and/or other materials provided with the distribution.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36 */
37
38#include "includes.h"
39
40#include <sys/types.h>
41#include <sys/stat.h>
42
43#include <openssl/evp.h>
44#include "openbsd-compat/openssl-compat.h"
45
46#include <errno.h>
47#include <fcntl.h>
48#include <pwd.h>
49#include <stdarg.h>
50#include <stdio.h>
51#include <stdlib.h>
52#include <string.h>
53#include <unistd.h>
54#include <limits.h>
55
56#include "xmalloc.h"
57#include "ssh.h"
58#include "log.h"
59#include "sshkey.h"
60#include "sshbuf.h"
61#include "authfd.h"
62#include "authfile.h"
63#include "pathnames.h"
64#include "misc.h"
65#include "ssherr.h"
66#include "digest.h"
67
68/* argv0 */
69extern char *__progname;
70
71/* Default files to add */
72static char *default_files[] = {
73#ifdef WITH_OPENSSL
74	_PATH_SSH_CLIENT_ID_RSA,
75	_PATH_SSH_CLIENT_ID_DSA,
76#ifdef OPENSSL_HAS_ECC
77	_PATH_SSH_CLIENT_ID_ECDSA,
78#endif
79#endif /* WITH_OPENSSL */
80	_PATH_SSH_CLIENT_ID_ED25519,
81	_PATH_SSH_CLIENT_ID_XMSS,
82	NULL
83};
84
85static int fingerprint_hash = SSH_FP_HASH_DEFAULT;
86
87/* Default lifetime (0 == forever) */
88static int lifetime = 0;
89
90/* User has to confirm key use */
91static int confirm = 0;
92
93/* Maximum number of signatures (XMSS) */
94static u_int maxsign = 0;
95static u_int minleft = 0;
96
97/* we keep a cache of one passphrase */
98static char *pass = NULL;
99static void
100clear_pass(void)
101{
102	if (pass) {
103		explicit_bzero(pass, strlen(pass));
104		free(pass);
105		pass = NULL;
106	}
107}
108
109static int
110delete_file(int agent_fd, const char *filename, int key_only, int qflag)
111{
112	struct sshkey *public, *cert = NULL;
113	char *certpath = NULL, *comment = NULL;
114	int r, ret = -1;
115
116	if ((r = sshkey_load_public(filename, &public,  &comment)) != 0) {
117		printf("Bad key file %s: %s\n", filename, ssh_err(r));
118		return -1;
119	}
120	if ((r = ssh_remove_identity(agent_fd, public)) == 0) {
121		if (!qflag) {
122			fprintf(stderr, "Identity removed: %s (%s)\n",
123			    filename, comment);
124		}
125		ret = 0;
126	} else
127		fprintf(stderr, "Could not remove identity \"%s\": %s\n",
128		    filename, ssh_err(r));
129
130	if (key_only)
131		goto out;
132
133	/* Now try to delete the corresponding certificate too */
134	free(comment);
135	comment = NULL;
136	xasprintf(&certpath, "%s-cert.pub", filename);
137	if ((r = sshkey_load_public(certpath, &cert, &comment)) != 0) {
138		if (r != SSH_ERR_SYSTEM_ERROR || errno != ENOENT)
139			error("Failed to load certificate \"%s\": %s",
140			    certpath, ssh_err(r));
141		goto out;
142	}
143
144	if (!sshkey_equal_public(cert, public))
145		fatal("Certificate %s does not match private key %s",
146		    certpath, filename);
147
148	if ((r = ssh_remove_identity(agent_fd, cert)) == 0) {
149		if (!qflag) {
150			fprintf(stderr, "Identity removed: %s (%s)\n",
151			    certpath, comment);
152		}
153		ret = 0;
154	} else
155		fprintf(stderr, "Could not remove identity \"%s\": %s\n",
156		    certpath, ssh_err(r));
157
158 out:
159	sshkey_free(cert);
160	sshkey_free(public);
161	free(certpath);
162	free(comment);
163
164	return ret;
165}
166
167/* Send a request to remove all identities. */
168static int
169delete_all(int agent_fd, int qflag)
170{
171	int ret = -1;
172
173	/*
174	 * Since the agent might be forwarded, old or non-OpenSSH, when asked
175	 * to remove all keys, attempt to remove both protocol v.1 and v.2
176	 * keys.
177	 */
178	if (ssh_remove_all_identities(agent_fd, 2) == 0)
179		ret = 0;
180	/* ignore error-code for ssh1 */
181	ssh_remove_all_identities(agent_fd, 1);
182
183	if (ret != 0)
184		fprintf(stderr, "Failed to remove all identities.\n");
185	else if (!qflag)
186		fprintf(stderr, "All identities removed.\n");
187
188	return ret;
189}
190
191static int
192add_file(int agent_fd, const char *filename, int key_only, int qflag)
193{
194	struct sshkey *private, *cert;
195	char *comment = NULL;
196	char msg[1024], *certpath = NULL;
197	int r, fd, ret = -1;
198	size_t i;
199	u_int32_t left;
200	struct sshbuf *keyblob;
201	struct ssh_identitylist *idlist;
202
203	if (strcmp(filename, "-") == 0) {
204		fd = STDIN_FILENO;
205		filename = "(stdin)";
206	} else if ((fd = open(filename, O_RDONLY)) < 0) {
207		perror(filename);
208		return -1;
209	}
210
211	/*
212	 * Since we'll try to load a keyfile multiple times, permission errors
213	 * will occur multiple times, so check perms first and bail if wrong.
214	 */
215	if (fd != STDIN_FILENO) {
216		if (sshkey_perm_ok(fd, filename) != 0) {
217			close(fd);
218			return -1;
219		}
220	}
221	if ((keyblob = sshbuf_new()) == NULL)
222		fatal("%s: sshbuf_new failed", __func__);
223	if ((r = sshkey_load_file(fd, keyblob)) != 0) {
224		fprintf(stderr, "Error loading key \"%s\": %s\n",
225		    filename, ssh_err(r));
226		sshbuf_free(keyblob);
227		close(fd);
228		return -1;
229	}
230	close(fd);
231
232	/* At first, try empty passphrase */
233	if ((r = sshkey_parse_private_fileblob(keyblob, "", &private,
234	    &comment)) != 0 && r != SSH_ERR_KEY_WRONG_PASSPHRASE) {
235		fprintf(stderr, "Error loading key \"%s\": %s\n",
236		    filename, ssh_err(r));
237		goto fail_load;
238	}
239	/* try last */
240	if (private == NULL && pass != NULL) {
241		if ((r = sshkey_parse_private_fileblob(keyblob, pass, &private,
242		    &comment)) != 0 && r != SSH_ERR_KEY_WRONG_PASSPHRASE) {
243			fprintf(stderr, "Error loading key \"%s\": %s\n",
244			    filename, ssh_err(r));
245			goto fail_load;
246		}
247	}
248	if (private == NULL) {
249		/* clear passphrase since it did not work */
250		clear_pass();
251		snprintf(msg, sizeof msg, "Enter passphrase for %s%s: ",
252		    filename, confirm ? " (will confirm each use)" : "");
253		for (;;) {
254			pass = read_passphrase(msg, RP_ALLOW_STDIN);
255			if (strcmp(pass, "") == 0)
256				goto fail_load;
257			if ((r = sshkey_parse_private_fileblob(keyblob, pass,
258			    &private, &comment)) == 0)
259				break;
260			else if (r != SSH_ERR_KEY_WRONG_PASSPHRASE) {
261				fprintf(stderr,
262				    "Error loading key \"%s\": %s\n",
263				    filename, ssh_err(r));
264 fail_load:
265				clear_pass();
266				sshbuf_free(keyblob);
267				return -1;
268			}
269			clear_pass();
270			snprintf(msg, sizeof msg,
271			    "Bad passphrase, try again for %s%s: ", filename,
272			    confirm ? " (will confirm each use)" : "");
273		}
274	}
275	if (comment == NULL || *comment == '\0')
276		comment = xstrdup(filename);
277	sshbuf_free(keyblob);
278
279	/* For XMSS */
280	if ((r = sshkey_set_filename(private, filename)) != 0) {
281		fprintf(stderr, "Could not add filename to private key: %s (%s)\n",
282		    filename, comment);
283		goto out;
284	}
285	if (maxsign && minleft &&
286	    (r = ssh_fetch_identitylist(agent_fd, &idlist)) == 0) {
287		for (i = 0; i < idlist->nkeys; i++) {
288			if (!sshkey_equal_public(idlist->keys[i], private))
289				continue;
290			left = sshkey_signatures_left(idlist->keys[i]);
291			if (left < minleft) {
292				fprintf(stderr,
293				    "Only %d signatures left.\n", left);
294				break;
295			}
296			fprintf(stderr, "Skipping update: ");
297			if (left == minleft) {
298				fprintf(stderr,
299				   "required signatures left (%d).\n", left);
300			} else {
301				fprintf(stderr,
302				   "more signatures left (%d) than"
303				    " required (%d).\n", left, minleft);
304			}
305			ssh_free_identitylist(idlist);
306			goto out;
307		}
308		ssh_free_identitylist(idlist);
309	}
310
311	if ((r = ssh_add_identity_constrained(agent_fd, private, comment,
312	    lifetime, confirm, maxsign)) == 0) {
313		ret = 0;
314		if (!qflag) {
315			fprintf(stderr, "Identity added: %s (%s)\n",
316			    filename, comment);
317			if (lifetime != 0) {
318				fprintf(stderr,
319				    "Lifetime set to %d seconds\n", lifetime);
320			}
321			if (confirm != 0) {
322				fprintf(stderr, "The user must confirm "
323				    "each use of the key\n");
324			}
325		}
326	} else {
327		fprintf(stderr, "Could not add identity \"%s\": %s\n",
328		    filename, ssh_err(r));
329	}
330
331	/* Skip trying to load the cert if requested */
332	if (key_only)
333		goto out;
334
335	/* Now try to add the certificate flavour too */
336	xasprintf(&certpath, "%s-cert.pub", filename);
337	if ((r = sshkey_load_public(certpath, &cert, NULL)) != 0) {
338		if (r != SSH_ERR_SYSTEM_ERROR || errno != ENOENT)
339			error("Failed to load certificate \"%s\": %s",
340			    certpath, ssh_err(r));
341		goto out;
342	}
343
344	if (!sshkey_equal_public(cert, private)) {
345		error("Certificate %s does not match private key %s",
346		    certpath, filename);
347		sshkey_free(cert);
348		goto out;
349	}
350
351	/* Graft with private bits */
352	if ((r = sshkey_to_certified(private)) != 0) {
353		error("%s: sshkey_to_certified: %s", __func__, ssh_err(r));
354		sshkey_free(cert);
355		goto out;
356	}
357	if ((r = sshkey_cert_copy(cert, private)) != 0) {
358		error("%s: sshkey_cert_copy: %s", __func__, ssh_err(r));
359		sshkey_free(cert);
360		goto out;
361	}
362	sshkey_free(cert);
363
364	if ((r = ssh_add_identity_constrained(agent_fd, private, comment,
365	    lifetime, confirm, maxsign)) != 0) {
366		error("Certificate %s (%s) add failed: %s", certpath,
367		    private->cert->key_id, ssh_err(r));
368		goto out;
369	}
370	/* success */
371	if (!qflag) {
372		fprintf(stderr, "Certificate added: %s (%s)\n", certpath,
373		    private->cert->key_id);
374		if (lifetime != 0) {
375			fprintf(stderr, "Lifetime set to %d seconds\n",
376			    lifetime);
377		}
378		if (confirm != 0) {
379			fprintf(stderr, "The user must confirm each use "
380			    "of the key\n");
381		}
382	}
383
384 out:
385	free(certpath);
386	free(comment);
387	sshkey_free(private);
388
389	return ret;
390}
391
392static int
393update_card(int agent_fd, int add, const char *id, int qflag)
394{
395	char *pin = NULL;
396	int r, ret = -1;
397
398	if (add) {
399		if ((pin = read_passphrase("Enter passphrase for PKCS#11: ",
400		    RP_ALLOW_STDIN)) == NULL)
401			return -1;
402	}
403
404	if ((r = ssh_update_card(agent_fd, add, id, pin == NULL ? "" : pin,
405	    lifetime, confirm)) == 0) {
406		ret = 0;
407		if (!qflag) {
408			fprintf(stderr, "Card %s: %s\n",
409			    add ? "added" : "removed", id);
410		}
411	} else {
412		fprintf(stderr, "Could not %s card \"%s\": %s\n",
413		    add ? "add" : "remove", id, ssh_err(r));
414		ret = -1;
415	}
416	free(pin);
417	return ret;
418}
419
420static int
421list_identities(int agent_fd, int do_fp)
422{
423	char *fp;
424	int r;
425	struct ssh_identitylist *idlist;
426	u_int32_t left;
427	size_t i;
428
429	if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) {
430		if (r != SSH_ERR_AGENT_NO_IDENTITIES)
431			fprintf(stderr, "error fetching identities: %s\n",
432			    ssh_err(r));
433		else
434			printf("The agent has no identities.\n");
435		return -1;
436	}
437	for (i = 0; i < idlist->nkeys; i++) {
438		if (do_fp) {
439			fp = sshkey_fingerprint(idlist->keys[i],
440			    fingerprint_hash, SSH_FP_DEFAULT);
441			printf("%u %s %s (%s)\n", sshkey_size(idlist->keys[i]),
442			    fp == NULL ? "(null)" : fp, idlist->comments[i],
443			    sshkey_type(idlist->keys[i]));
444			free(fp);
445		} else {
446			if ((r = sshkey_write(idlist->keys[i], stdout)) != 0) {
447				fprintf(stderr, "sshkey_write: %s\n",
448				    ssh_err(r));
449				continue;
450			}
451			fprintf(stdout, " %s", idlist->comments[i]);
452			left = sshkey_signatures_left(idlist->keys[i]);
453			if (left > 0)
454				fprintf(stdout,
455				    " [signatures left %d]", left);
456			fprintf(stdout, "\n");
457		}
458	}
459	ssh_free_identitylist(idlist);
460	return 0;
461}
462
463static int
464lock_agent(int agent_fd, int lock)
465{
466	char prompt[100], *p1, *p2;
467	int r, passok = 1, ret = -1;
468
469	strlcpy(prompt, "Enter lock password: ", sizeof(prompt));
470	p1 = read_passphrase(prompt, RP_ALLOW_STDIN);
471	if (lock) {
472		strlcpy(prompt, "Again: ", sizeof prompt);
473		p2 = read_passphrase(prompt, RP_ALLOW_STDIN);
474		if (strcmp(p1, p2) != 0) {
475			fprintf(stderr, "Passwords do not match.\n");
476			passok = 0;
477		}
478		explicit_bzero(p2, strlen(p2));
479		free(p2);
480	}
481	if (passok) {
482		if ((r = ssh_lock_agent(agent_fd, lock, p1)) == 0) {
483			fprintf(stderr, "Agent %slocked.\n", lock ? "" : "un");
484			ret = 0;
485		} else {
486			fprintf(stderr, "Failed to %slock agent: %s\n",
487			    lock ? "" : "un", ssh_err(r));
488		}
489	}
490	explicit_bzero(p1, strlen(p1));
491	free(p1);
492	return (ret);
493}
494
495static int
496do_file(int agent_fd, int deleting, int key_only, char *file, int qflag)
497{
498	if (deleting) {
499		if (delete_file(agent_fd, file, key_only, qflag) == -1)
500			return -1;
501	} else {
502		if (add_file(agent_fd, file, key_only, qflag) == -1)
503			return -1;
504	}
505	return 0;
506}
507
508static void
509usage(void)
510{
511	fprintf(stderr, "usage: %s [options] [file ...]\n", __progname);
512	fprintf(stderr, "Options:\n");
513	fprintf(stderr, "  -l          List fingerprints of all identities.\n");
514	fprintf(stderr, "  -E hash     Specify hash algorithm used for fingerprints.\n");
515	fprintf(stderr, "  -L          List public key parameters of all identities.\n");
516	fprintf(stderr, "  -k          Load only keys and not certificates.\n");
517	fprintf(stderr, "  -c          Require confirmation to sign using identities\n");
518	fprintf(stderr, "  -m minleft  Maxsign is only changed if less than minleft are left (for XMSS)\n");
519	fprintf(stderr, "  -M maxsign  Maximum number of signatures allowed (for XMSS)\n");
520	fprintf(stderr, "  -t life     Set lifetime (in seconds) when adding identities.\n");
521	fprintf(stderr, "  -d          Delete identity.\n");
522	fprintf(stderr, "  -D          Delete all identities.\n");
523	fprintf(stderr, "  -x          Lock agent.\n");
524	fprintf(stderr, "  -X          Unlock agent.\n");
525	fprintf(stderr, "  -s pkcs11   Add keys from PKCS#11 provider.\n");
526	fprintf(stderr, "  -e pkcs11   Remove keys provided by PKCS#11 provider.\n");
527	fprintf(stderr, "  -q          Be quiet after a successful operation.\n");
528}
529
530int
531main(int argc, char **argv)
532{
533	extern char *optarg;
534	extern int optind;
535	int agent_fd;
536	char *pkcs11provider = NULL;
537	int r, i, ch, deleting = 0, ret = 0, key_only = 0;
538	int xflag = 0, lflag = 0, Dflag = 0, qflag = 0;
539
540	ssh_malloc_init();	/* must be called before any mallocs */
541	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
542	sanitise_stdfd();
543
544	__progname = ssh_get_progname(argv[0]);
545	seed_rng();
546
547#ifdef WITH_OPENSSL
548	OpenSSL_add_all_algorithms();
549#endif
550
551	setvbuf(stdout, NULL, _IOLBF, 0);
552
553	/* First, get a connection to the authentication agent. */
554	switch (r = ssh_get_authentication_socket(&agent_fd)) {
555	case 0:
556		break;
557	case SSH_ERR_AGENT_NOT_PRESENT:
558		fprintf(stderr, "Could not open a connection to your "
559		    "authentication agent.\n");
560		exit(2);
561	default:
562		fprintf(stderr, "Error connecting to agent: %s\n", ssh_err(r));
563		exit(2);
564	}
565
566	while ((ch = getopt(argc, argv, "klLcdDxXE:e:M:m:qs:t:")) != -1) {
567		switch (ch) {
568		case 'E':
569			fingerprint_hash = ssh_digest_alg_by_name(optarg);
570			if (fingerprint_hash == -1)
571				fatal("Invalid hash algorithm \"%s\"", optarg);
572			break;
573		case 'k':
574			key_only = 1;
575			break;
576		case 'l':
577		case 'L':
578			if (lflag != 0)
579				fatal("-%c flag already specified", lflag);
580			lflag = ch;
581			break;
582		case 'x':
583		case 'X':
584			if (xflag != 0)
585				fatal("-%c flag already specified", xflag);
586			xflag = ch;
587			break;
588		case 'c':
589			confirm = 1;
590			break;
591		case 'm':
592			minleft = (int)strtonum(optarg, 1, UINT_MAX, NULL);
593			if (minleft == 0) {
594				usage();
595				ret = 1;
596				goto done;
597			}
598			break;
599		case 'M':
600			maxsign = (int)strtonum(optarg, 1, UINT_MAX, NULL);
601			if (maxsign == 0) {
602				usage();
603				ret = 1;
604				goto done;
605			}
606			break;
607		case 'd':
608			deleting = 1;
609			break;
610		case 'D':
611			Dflag = 1;
612			break;
613		case 's':
614			pkcs11provider = optarg;
615			break;
616		case 'e':
617			deleting = 1;
618			pkcs11provider = optarg;
619			break;
620		case 't':
621			if ((lifetime = convtime(optarg)) == -1) {
622				fprintf(stderr, "Invalid lifetime\n");
623				ret = 1;
624				goto done;
625			}
626			break;
627		case 'q':
628			qflag = 1;
629			break;
630		default:
631			usage();
632			ret = 1;
633			goto done;
634		}
635	}
636
637	if ((xflag != 0) + (lflag != 0) + (Dflag != 0) > 1)
638		fatal("Invalid combination of actions");
639	else if (xflag) {
640		if (lock_agent(agent_fd, xflag == 'x' ? 1 : 0) == -1)
641			ret = 1;
642		goto done;
643	} else if (lflag) {
644		if (list_identities(agent_fd, lflag == 'l' ? 1 : 0) == -1)
645			ret = 1;
646		goto done;
647	} else if (Dflag) {
648		if (delete_all(agent_fd, qflag) == -1)
649			ret = 1;
650		goto done;
651	}
652
653	argc -= optind;
654	argv += optind;
655	if (pkcs11provider != NULL) {
656		if (update_card(agent_fd, !deleting, pkcs11provider,
657		    qflag) == -1)
658			ret = 1;
659		goto done;
660	}
661	if (argc == 0) {
662		char buf[PATH_MAX];
663		struct passwd *pw;
664		struct stat st;
665		int count = 0;
666
667		if ((pw = getpwuid(getuid())) == NULL) {
668			fprintf(stderr, "No user found with uid %u\n",
669			    (u_int)getuid());
670			ret = 1;
671			goto done;
672		}
673
674		for (i = 0; default_files[i]; i++) {
675			snprintf(buf, sizeof(buf), "%s/%s", pw->pw_dir,
676			    default_files[i]);
677			if (stat(buf, &st) < 0)
678				continue;
679			if (do_file(agent_fd, deleting, key_only, buf,
680			    qflag) == -1)
681				ret = 1;
682			else
683				count++;
684		}
685		if (count == 0)
686			ret = 1;
687	} else {
688		for (i = 0; i < argc; i++) {
689			if (do_file(agent_fd, deleting, key_only,
690			    argv[i], qflag) == -1)
691				ret = 1;
692		}
693	}
694	clear_pass();
695
696done:
697	ssh_close_authentication_socket(agent_fd);
698	return ret;
699}
700