1 /* $OpenBSD: auth-options.c,v 1.101 2023/07/14 07:44:21 dtucker Exp $ */
2 /*
3 * Copyright (c) 2018 Damien Miller <djm@mindrot.org>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 #include <sys/types.h>
19 #include <sys/queue.h>
20
21 #include <stdlib.h>
22 #include <netdb.h>
23 #include <pwd.h>
24 #include <string.h>
25 #include <stdio.h>
26 #include <stdint.h>
27 #include <stdarg.h>
28 #include <ctype.h>
29 #include <limits.h>
30
31 #include "xmalloc.h"
32 #include "ssherr.h"
33 #include "log.h"
34 #include "sshbuf.h"
35 #include "misc.h"
36 #include "sshkey.h"
37 #include "match.h"
38 #include "ssh2.h"
39 #include "auth-options.h"
40
41 static int
dup_strings(char *** dstp,size_t * ndstp,char ** src,size_t nsrc)42 dup_strings(char ***dstp, size_t *ndstp, char **src, size_t nsrc)
43 {
44 char **dst;
45 size_t i, j;
46
47 *dstp = NULL;
48 *ndstp = 0;
49
50 if (nsrc == 0)
51 return 0;
52 if (nsrc >= SIZE_MAX / sizeof(*src) ||
53 (dst = calloc(nsrc, sizeof(*src))) == NULL)
54 return -1;
55 for (i = 0; i < nsrc; i++) {
56 if ((dst[i] = strdup(src[i])) == NULL) {
57 for (j = 0; j < i; j++)
58 free(dst[j]);
59 free(dst);
60 return -1;
61 }
62 }
63 /* success */
64 *dstp = dst;
65 *ndstp = nsrc;
66 return 0;
67 }
68
69 #define OPTIONS_CRITICAL 1
70 #define OPTIONS_EXTENSIONS 2
71 static int
cert_option_list(struct sshauthopt * opts,struct sshbuf * oblob,u_int which,int crit)72 cert_option_list(struct sshauthopt *opts, struct sshbuf *oblob,
73 u_int which, int crit)
74 {
75 char *command, *allowed;
76 char *name = NULL;
77 struct sshbuf *c = NULL, *data = NULL;
78 int r, ret = -1, found;
79
80 if ((c = sshbuf_fromb(oblob)) == NULL) {
81 error_f("sshbuf_fromb failed");
82 goto out;
83 }
84
85 while (sshbuf_len(c) > 0) {
86 sshbuf_free(data);
87 data = NULL;
88 if ((r = sshbuf_get_cstring(c, &name, NULL)) != 0 ||
89 (r = sshbuf_froms(c, &data)) != 0) {
90 error_r(r, "Unable to parse certificate options");
91 goto out;
92 }
93 debug3("found certificate option \"%.100s\" len %zu",
94 name, sshbuf_len(data));
95 found = 0;
96 if ((which & OPTIONS_EXTENSIONS) != 0) {
97 if (strcmp(name, "no-touch-required") == 0) {
98 opts->no_require_user_presence = 1;
99 found = 1;
100 } else if (strcmp(name, "permit-X11-forwarding") == 0) {
101 opts->permit_x11_forwarding_flag = 1;
102 found = 1;
103 } else if (strcmp(name,
104 "permit-agent-forwarding") == 0) {
105 opts->permit_agent_forwarding_flag = 1;
106 found = 1;
107 } else if (strcmp(name,
108 "permit-port-forwarding") == 0) {
109 opts->permit_port_forwarding_flag = 1;
110 found = 1;
111 } else if (strcmp(name, "permit-pty") == 0) {
112 opts->permit_pty_flag = 1;
113 found = 1;
114 } else if (strcmp(name, "permit-user-rc") == 0) {
115 opts->permit_user_rc = 1;
116 found = 1;
117 }
118 }
119 if (!found && (which & OPTIONS_CRITICAL) != 0) {
120 if (strcmp(name, "verify-required") == 0) {
121 opts->require_verify = 1;
122 found = 1;
123 } else if (strcmp(name, "force-command") == 0) {
124 if ((r = sshbuf_get_cstring(data, &command,
125 NULL)) != 0) {
126 error_r(r, "Unable to parse \"%s\" "
127 "section", name);
128 goto out;
129 }
130 if (opts->force_command != NULL) {
131 error("Certificate has multiple "
132 "force-command options");
133 free(command);
134 goto out;
135 }
136 opts->force_command = command;
137 found = 1;
138 } else if (strcmp(name, "source-address") == 0) {
139 if ((r = sshbuf_get_cstring(data, &allowed,
140 NULL)) != 0) {
141 error_r(r, "Unable to parse \"%s\" "
142 "section", name);
143 goto out;
144 }
145 if (opts->required_from_host_cert != NULL) {
146 error("Certificate has multiple "
147 "source-address options");
148 free(allowed);
149 goto out;
150 }
151 /* Check syntax */
152 if (addr_match_cidr_list(NULL, allowed) == -1) {
153 error("Certificate source-address "
154 "contents invalid");
155 goto out;
156 }
157 opts->required_from_host_cert = allowed;
158 found = 1;
159 }
160 }
161
162 if (!found) {
163 if (crit) {
164 error("Certificate critical option \"%s\" "
165 "is not supported", name);
166 goto out;
167 } else {
168 logit("Certificate extension \"%s\" "
169 "is not supported", name);
170 }
171 } else if (sshbuf_len(data) != 0) {
172 error("Certificate option \"%s\" corrupt "
173 "(extra data)", name);
174 goto out;
175 }
176 free(name);
177 name = NULL;
178 }
179 /* successfully parsed all options */
180 ret = 0;
181
182 out:
183 free(name);
184 sshbuf_free(data);
185 sshbuf_free(c);
186 return ret;
187 }
188
189 struct sshauthopt *
sshauthopt_new(void)190 sshauthopt_new(void)
191 {
192 struct sshauthopt *ret;
193
194 if ((ret = calloc(1, sizeof(*ret))) == NULL)
195 return NULL;
196 ret->force_tun_device = -1;
197 return ret;
198 }
199
200 void
sshauthopt_free(struct sshauthopt * opts)201 sshauthopt_free(struct sshauthopt *opts)
202 {
203 size_t i;
204
205 if (opts == NULL)
206 return;
207
208 free(opts->cert_principals);
209 free(opts->force_command);
210 free(opts->required_from_host_cert);
211 free(opts->required_from_host_keys);
212
213 for (i = 0; i < opts->nenv; i++)
214 free(opts->env[i]);
215 free(opts->env);
216
217 for (i = 0; i < opts->npermitopen; i++)
218 free(opts->permitopen[i]);
219 free(opts->permitopen);
220
221 for (i = 0; i < opts->npermitlisten; i++)
222 free(opts->permitlisten[i]);
223 free(opts->permitlisten);
224
225 freezero(opts, sizeof(*opts));
226 }
227
228 struct sshauthopt *
sshauthopt_new_with_keys_defaults(void)229 sshauthopt_new_with_keys_defaults(void)
230 {
231 struct sshauthopt *ret = NULL;
232
233 if ((ret = sshauthopt_new()) == NULL)
234 return NULL;
235
236 /* Defaults for authorized_keys flags */
237 ret->permit_port_forwarding_flag = 1;
238 ret->permit_agent_forwarding_flag = 1;
239 ret->permit_x11_forwarding_flag = 1;
240 ret->permit_pty_flag = 1;
241 ret->permit_user_rc = 1;
242 return ret;
243 }
244
245 /*
246 * Parse and record a permitopen/permitlisten directive.
247 * Return 0 on success. Return -1 on failure and sets *errstrp to error reason.
248 */
249 static int
handle_permit(const char ** optsp,int allow_bare_port,char *** permitsp,size_t * npermitsp,const char ** errstrp)250 handle_permit(const char **optsp, int allow_bare_port,
251 char ***permitsp, size_t *npermitsp, const char **errstrp)
252 {
253 char *opt, *tmp, *cp, *host, **permits = *permitsp;
254 size_t npermits = *npermitsp;
255 const char *errstr = "unknown error";
256
257 if (npermits > SSH_AUTHOPT_PERMIT_MAX) {
258 *errstrp = "too many permission directives";
259 return -1;
260 }
261 if ((opt = opt_dequote(optsp, &errstr)) == NULL) {
262 return -1;
263 }
264 if (allow_bare_port && strchr(opt, ':') == NULL) {
265 /*
266 * Allow a bare port number in permitlisten to indicate a
267 * listen_host wildcard.
268 */
269 if (asprintf(&tmp, "*:%s", opt) == -1) {
270 free(opt);
271 *errstrp = "memory allocation failed";
272 return -1;
273 }
274 free(opt);
275 opt = tmp;
276 }
277 if ((tmp = strdup(opt)) == NULL) {
278 free(opt);
279 *errstrp = "memory allocation failed";
280 return -1;
281 }
282 cp = tmp;
283 /* validate syntax before recording it. */
284 host = hpdelim2(&cp, NULL);
285 if (host == NULL || strlen(host) >= NI_MAXHOST) {
286 free(tmp);
287 free(opt);
288 *errstrp = "invalid permission hostname";
289 return -1;
290 }
291 /*
292 * don't want to use permitopen_port to avoid
293 * dependency on channels.[ch] here.
294 */
295 if (cp == NULL ||
296 (strcmp(cp, "*") != 0 && a2port(cp) <= 0)) {
297 free(tmp);
298 free(opt);
299 *errstrp = "invalid permission port";
300 return -1;
301 }
302 /* XXX - add streamlocal support */
303 free(tmp);
304 /* Record it */
305 if ((permits = recallocarray(permits, npermits, npermits + 1,
306 sizeof(*permits))) == NULL) {
307 free(opt);
308 /* NB. don't update *permitsp if alloc fails */
309 *errstrp = "memory allocation failed";
310 return -1;
311 }
312 permits[npermits++] = opt;
313 *permitsp = permits;
314 *npermitsp = npermits;
315 return 0;
316 }
317
318 struct sshauthopt *
sshauthopt_parse(const char * opts,const char ** errstrp)319 sshauthopt_parse(const char *opts, const char **errstrp)
320 {
321 char **oarray, *opt, *cp, *tmp;
322 int r;
323 struct sshauthopt *ret = NULL;
324 const char *errstr = "unknown error";
325 uint64_t valid_before;
326 size_t i, l;
327
328 if (errstrp != NULL)
329 *errstrp = NULL;
330 if ((ret = sshauthopt_new_with_keys_defaults()) == NULL)
331 goto alloc_fail;
332
333 if (opts == NULL)
334 return ret;
335
336 while (*opts && *opts != ' ' && *opts != '\t') {
337 /* flag options */
338 if ((r = opt_flag("restrict", 0, &opts)) != -1) {
339 ret->restricted = 1;
340 ret->permit_port_forwarding_flag = 0;
341 ret->permit_agent_forwarding_flag = 0;
342 ret->permit_x11_forwarding_flag = 0;
343 ret->permit_pty_flag = 0;
344 ret->permit_user_rc = 0;
345 } else if ((r = opt_flag("cert-authority", 0, &opts)) != -1) {
346 ret->cert_authority = r;
347 } else if ((r = opt_flag("port-forwarding", 1, &opts)) != -1) {
348 ret->permit_port_forwarding_flag = r == 1;
349 } else if ((r = opt_flag("agent-forwarding", 1, &opts)) != -1) {
350 ret->permit_agent_forwarding_flag = r == 1;
351 } else if ((r = opt_flag("x11-forwarding", 1, &opts)) != -1) {
352 ret->permit_x11_forwarding_flag = r == 1;
353 } else if ((r = opt_flag("touch-required", 1, &opts)) != -1) {
354 ret->no_require_user_presence = r != 1; /* NB. flip */
355 } else if ((r = opt_flag("verify-required", 1, &opts)) != -1) {
356 ret->require_verify = r == 1;
357 } else if ((r = opt_flag("pty", 1, &opts)) != -1) {
358 ret->permit_pty_flag = r == 1;
359 } else if ((r = opt_flag("user-rc", 1, &opts)) != -1) {
360 ret->permit_user_rc = r == 1;
361 } else if (opt_match(&opts, "command")) {
362 if (ret->force_command != NULL) {
363 errstr = "multiple \"command\" clauses";
364 goto fail;
365 }
366 ret->force_command = opt_dequote(&opts, &errstr);
367 if (ret->force_command == NULL)
368 goto fail;
369 } else if (opt_match(&opts, "principals")) {
370 if (ret->cert_principals != NULL) {
371 errstr = "multiple \"principals\" clauses";
372 goto fail;
373 }
374 ret->cert_principals = opt_dequote(&opts, &errstr);
375 if (ret->cert_principals == NULL)
376 goto fail;
377 } else if (opt_match(&opts, "from")) {
378 if (ret->required_from_host_keys != NULL) {
379 errstr = "multiple \"from\" clauses";
380 goto fail;
381 }
382 ret->required_from_host_keys = opt_dequote(&opts,
383 &errstr);
384 if (ret->required_from_host_keys == NULL)
385 goto fail;
386 } else if (opt_match(&opts, "expiry-time")) {
387 if ((opt = opt_dequote(&opts, &errstr)) == NULL)
388 goto fail;
389 if (parse_absolute_time(opt, &valid_before) != 0 ||
390 valid_before == 0) {
391 free(opt);
392 errstr = "invalid expires time";
393 goto fail;
394 }
395 free(opt);
396 if (ret->valid_before == 0 ||
397 valid_before < ret->valid_before)
398 ret->valid_before = valid_before;
399 } else if (opt_match(&opts, "environment")) {
400 if (ret->nenv > SSH_AUTHOPT_ENV_MAX) {
401 errstr = "too many environment strings";
402 goto fail;
403 }
404 if ((opt = opt_dequote(&opts, &errstr)) == NULL)
405 goto fail;
406 /* env name must be alphanumeric and followed by '=' */
407 if ((tmp = strchr(opt, '=')) == NULL) {
408 free(opt);
409 errstr = "invalid environment string";
410 goto fail;
411 }
412 if ((cp = strdup(opt)) == NULL) {
413 free(opt);
414 goto alloc_fail;
415 }
416 l = (size_t)(tmp - opt);
417 cp[l] = '\0'; /* truncate at '=' */
418 if (!valid_env_name(cp)) {
419 free(cp);
420 free(opt);
421 errstr = "invalid environment string";
422 goto fail;
423 }
424 /* Check for duplicates; XXX O(n*log(n)) */
425 for (i = 0; i < ret->nenv; i++) {
426 if (strncmp(ret->env[i], cp, l) == 0 &&
427 ret->env[i][l] == '=')
428 break;
429 }
430 free(cp);
431 /* First match wins */
432 if (i >= ret->nenv) {
433 /* Append it. */
434 oarray = ret->env;
435 if ((ret->env = recallocarray(ret->env,
436 ret->nenv, ret->nenv + 1,
437 sizeof(*ret->env))) == NULL) {
438 free(opt);
439 /* put it back for cleanup */
440 ret->env = oarray;
441 goto alloc_fail;
442 }
443 ret->env[ret->nenv++] = opt;
444 opt = NULL; /* transferred */
445 }
446 free(opt);
447 } else if (opt_match(&opts, "permitopen")) {
448 if (handle_permit(&opts, 0, &ret->permitopen,
449 &ret->npermitopen, &errstr) != 0)
450 goto fail;
451 } else if (opt_match(&opts, "permitlisten")) {
452 if (handle_permit(&opts, 1, &ret->permitlisten,
453 &ret->npermitlisten, &errstr) != 0)
454 goto fail;
455 } else if (opt_match(&opts, "tunnel")) {
456 if ((opt = opt_dequote(&opts, &errstr)) == NULL)
457 goto fail;
458 ret->force_tun_device = a2tun(opt, NULL);
459 free(opt);
460 if (ret->force_tun_device == SSH_TUNID_ERR) {
461 errstr = "invalid tun device";
462 goto fail;
463 }
464 }
465 /*
466 * Skip the comma, and move to the next option
467 * (or break out if there are no more).
468 */
469 if (*opts == '\0' || *opts == ' ' || *opts == '\t')
470 break; /* End of options. */
471 /* Anything other than a comma is an unknown option */
472 if (*opts != ',') {
473 errstr = "unknown key option";
474 goto fail;
475 }
476 opts++;
477 if (*opts == '\0') {
478 errstr = "unexpected end-of-options";
479 goto fail;
480 }
481 }
482
483 /* success */
484 if (errstrp != NULL)
485 *errstrp = NULL;
486 return ret;
487
488 alloc_fail:
489 errstr = "memory allocation failed";
490 fail:
491 sshauthopt_free(ret);
492 if (errstrp != NULL)
493 *errstrp = errstr;
494 return NULL;
495 }
496
497 struct sshauthopt *
sshauthopt_from_cert(struct sshkey * k)498 sshauthopt_from_cert(struct sshkey *k)
499 {
500 struct sshauthopt *ret;
501
502 if (k == NULL || !sshkey_type_is_cert(k->type) || k->cert == NULL ||
503 k->cert->type != SSH2_CERT_TYPE_USER)
504 return NULL;
505
506 if ((ret = sshauthopt_new()) == NULL)
507 return NULL;
508
509 /* Handle options and critical extensions separately */
510 if (cert_option_list(ret, k->cert->critical,
511 OPTIONS_CRITICAL, 1) == -1) {
512 sshauthopt_free(ret);
513 return NULL;
514 }
515 if (cert_option_list(ret, k->cert->extensions,
516 OPTIONS_EXTENSIONS, 0) == -1) {
517 sshauthopt_free(ret);
518 return NULL;
519 }
520 /* success */
521 return ret;
522 }
523
524 /*
525 * Merges "additional" options to "primary" and returns the result.
526 * NB. Some options from primary have primacy.
527 */
528 struct sshauthopt *
sshauthopt_merge(const struct sshauthopt * primary,const struct sshauthopt * additional,const char ** errstrp)529 sshauthopt_merge(const struct sshauthopt *primary,
530 const struct sshauthopt *additional, const char **errstrp)
531 {
532 struct sshauthopt *ret;
533 const char *errstr = "internal error";
534 const char *tmp;
535
536 if (errstrp != NULL)
537 *errstrp = NULL;
538
539 if ((ret = sshauthopt_new()) == NULL)
540 goto alloc_fail;
541
542 /* cert_authority and cert_principals are cleared in result */
543
544 /* Prefer access lists from primary. */
545 /* XXX err is both set and mismatch? */
546 tmp = primary->required_from_host_cert;
547 if (tmp == NULL)
548 tmp = additional->required_from_host_cert;
549 if (tmp != NULL && (ret->required_from_host_cert = strdup(tmp)) == NULL)
550 goto alloc_fail;
551 tmp = primary->required_from_host_keys;
552 if (tmp == NULL)
553 tmp = additional->required_from_host_keys;
554 if (tmp != NULL && (ret->required_from_host_keys = strdup(tmp)) == NULL)
555 goto alloc_fail;
556
557 /*
558 * force_tun_device, permitopen/permitlisten and environment all
559 * prefer the primary.
560 */
561 ret->force_tun_device = primary->force_tun_device;
562 if (ret->force_tun_device == -1)
563 ret->force_tun_device = additional->force_tun_device;
564 if (primary->nenv > 0) {
565 if (dup_strings(&ret->env, &ret->nenv,
566 primary->env, primary->nenv) != 0)
567 goto alloc_fail;
568 } else if (additional->nenv) {
569 if (dup_strings(&ret->env, &ret->nenv,
570 additional->env, additional->nenv) != 0)
571 goto alloc_fail;
572 }
573 if (primary->npermitopen > 0) {
574 if (dup_strings(&ret->permitopen, &ret->npermitopen,
575 primary->permitopen, primary->npermitopen) != 0)
576 goto alloc_fail;
577 } else if (additional->npermitopen > 0) {
578 if (dup_strings(&ret->permitopen, &ret->npermitopen,
579 additional->permitopen, additional->npermitopen) != 0)
580 goto alloc_fail;
581 }
582
583 if (primary->npermitlisten > 0) {
584 if (dup_strings(&ret->permitlisten, &ret->npermitlisten,
585 primary->permitlisten, primary->npermitlisten) != 0)
586 goto alloc_fail;
587 } else if (additional->npermitlisten > 0) {
588 if (dup_strings(&ret->permitlisten, &ret->npermitlisten,
589 additional->permitlisten, additional->npermitlisten) != 0)
590 goto alloc_fail;
591 }
592
593 #define OPTFLAG_AND(x) ret->x = (primary->x == 1) && (additional->x == 1)
594 #define OPTFLAG_OR(x) ret->x = (primary->x == 1) || (additional->x == 1)
595 /* Permissive flags are logical-AND (i.e. must be set in both) */
596 OPTFLAG_AND(permit_port_forwarding_flag);
597 OPTFLAG_AND(permit_agent_forwarding_flag);
598 OPTFLAG_AND(permit_x11_forwarding_flag);
599 OPTFLAG_AND(permit_pty_flag);
600 OPTFLAG_AND(permit_user_rc);
601 OPTFLAG_AND(no_require_user_presence);
602 /* Restrictive flags are logical-OR (i.e. must be set in either) */
603 OPTFLAG_OR(require_verify);
604 #undef OPTFLAG_AND
605
606 /* Earliest expiry time should win */
607 if (primary->valid_before != 0)
608 ret->valid_before = primary->valid_before;
609 if (additional->valid_before != 0 &&
610 additional->valid_before < ret->valid_before)
611 ret->valid_before = additional->valid_before;
612
613 /*
614 * When both multiple forced-command are specified, only
615 * proceed if they are identical, otherwise fail.
616 */
617 if (primary->force_command != NULL &&
618 additional->force_command != NULL) {
619 if (strcmp(primary->force_command,
620 additional->force_command) == 0) {
621 /* ok */
622 ret->force_command = strdup(primary->force_command);
623 if (ret->force_command == NULL)
624 goto alloc_fail;
625 } else {
626 errstr = "forced command options do not match";
627 goto fail;
628 }
629 } else if (primary->force_command != NULL) {
630 if ((ret->force_command = strdup(
631 primary->force_command)) == NULL)
632 goto alloc_fail;
633 } else if (additional->force_command != NULL) {
634 if ((ret->force_command = strdup(
635 additional->force_command)) == NULL)
636 goto alloc_fail;
637 }
638 /* success */
639 if (errstrp != NULL)
640 *errstrp = NULL;
641 return ret;
642
643 alloc_fail:
644 errstr = "memory allocation failed";
645 fail:
646 if (errstrp != NULL)
647 *errstrp = errstr;
648 sshauthopt_free(ret);
649 return NULL;
650 }
651
652 /*
653 * Copy options
654 */
655 struct sshauthopt *
sshauthopt_copy(const struct sshauthopt * orig)656 sshauthopt_copy(const struct sshauthopt *orig)
657 {
658 struct sshauthopt *ret;
659
660 if ((ret = sshauthopt_new()) == NULL)
661 return NULL;
662
663 #define OPTSCALAR(x) ret->x = orig->x
664 OPTSCALAR(permit_port_forwarding_flag);
665 OPTSCALAR(permit_agent_forwarding_flag);
666 OPTSCALAR(permit_x11_forwarding_flag);
667 OPTSCALAR(permit_pty_flag);
668 OPTSCALAR(permit_user_rc);
669 OPTSCALAR(restricted);
670 OPTSCALAR(cert_authority);
671 OPTSCALAR(force_tun_device);
672 OPTSCALAR(valid_before);
673 OPTSCALAR(no_require_user_presence);
674 OPTSCALAR(require_verify);
675 #undef OPTSCALAR
676 #define OPTSTRING(x) \
677 do { \
678 if (orig->x != NULL && (ret->x = strdup(orig->x)) == NULL) { \
679 sshauthopt_free(ret); \
680 return NULL; \
681 } \
682 } while (0)
683 OPTSTRING(cert_principals);
684 OPTSTRING(force_command);
685 OPTSTRING(required_from_host_cert);
686 OPTSTRING(required_from_host_keys);
687 #undef OPTSTRING
688
689 if (dup_strings(&ret->env, &ret->nenv, orig->env, orig->nenv) != 0 ||
690 dup_strings(&ret->permitopen, &ret->npermitopen,
691 orig->permitopen, orig->npermitopen) != 0 ||
692 dup_strings(&ret->permitlisten, &ret->npermitlisten,
693 orig->permitlisten, orig->npermitlisten) != 0) {
694 sshauthopt_free(ret);
695 return NULL;
696 }
697 return ret;
698 }
699
700 static int
serialise_array(struct sshbuf * m,char ** a,size_t n)701 serialise_array(struct sshbuf *m, char **a, size_t n)
702 {
703 struct sshbuf *b;
704 size_t i;
705 int r = SSH_ERR_INTERNAL_ERROR;
706
707 if (n > INT_MAX)
708 return SSH_ERR_INTERNAL_ERROR;
709
710 if ((b = sshbuf_new()) == NULL) {
711 return SSH_ERR_ALLOC_FAIL;
712 }
713 for (i = 0; i < n; i++) {
714 if ((r = sshbuf_put_cstring(b, a[i])) != 0)
715 goto out;
716 }
717 if ((r = sshbuf_put_u32(m, n)) != 0 ||
718 (r = sshbuf_put_stringb(m, b)) != 0)
719 goto out;
720 /* success */
721 r = 0;
722 out:
723 sshbuf_free(b);
724 return r;
725 }
726
727 static int
deserialise_array(struct sshbuf * m,char *** ap,size_t * np)728 deserialise_array(struct sshbuf *m, char ***ap, size_t *np)
729 {
730 char **a = NULL;
731 size_t i, n = 0;
732 struct sshbuf *b = NULL;
733 u_int tmp;
734 int r = SSH_ERR_INTERNAL_ERROR;
735
736 if ((r = sshbuf_get_u32(m, &tmp)) != 0 ||
737 (r = sshbuf_froms(m, &b)) != 0)
738 goto out;
739 if (tmp > INT_MAX) {
740 r = SSH_ERR_INVALID_FORMAT;
741 goto out;
742 }
743 n = tmp;
744 if (n > 0 && (a = calloc(n, sizeof(*a))) == NULL) {
745 r = SSH_ERR_ALLOC_FAIL;
746 goto out;
747 }
748 for (i = 0; i < n; i++) {
749 if ((r = sshbuf_get_cstring(b, &a[i], NULL)) != 0)
750 goto out;
751 }
752 /* success */
753 r = 0;
754 *ap = a;
755 a = NULL;
756 *np = n;
757 n = 0;
758 out:
759 if (a != NULL) {
760 for (i = 0; i < n; i++)
761 free(a[i]);
762 free(a);
763 }
764 sshbuf_free(b);
765 return r;
766 }
767
768 static int
serialise_nullable_string(struct sshbuf * m,const char * s)769 serialise_nullable_string(struct sshbuf *m, const char *s)
770 {
771 int r;
772
773 if ((r = sshbuf_put_u8(m, s == NULL)) != 0 ||
774 (r = sshbuf_put_cstring(m, s)) != 0)
775 return r;
776 return 0;
777 }
778
779 static int
deserialise_nullable_string(struct sshbuf * m,char ** sp)780 deserialise_nullable_string(struct sshbuf *m, char **sp)
781 {
782 int r;
783 u_char flag;
784
785 *sp = NULL;
786 if ((r = sshbuf_get_u8(m, &flag)) != 0 ||
787 (r = sshbuf_get_cstring(m, flag ? NULL : sp, NULL)) != 0)
788 return r;
789 return 0;
790 }
791
792 int
sshauthopt_serialise(const struct sshauthopt * opts,struct sshbuf * m,int untrusted)793 sshauthopt_serialise(const struct sshauthopt *opts, struct sshbuf *m,
794 int untrusted)
795 {
796 int r = SSH_ERR_INTERNAL_ERROR;
797
798 /* Flag options */
799 if ((r = sshbuf_put_u8(m, opts->permit_port_forwarding_flag)) != 0 ||
800 (r = sshbuf_put_u8(m, opts->permit_agent_forwarding_flag)) != 0 ||
801 (r = sshbuf_put_u8(m, opts->permit_x11_forwarding_flag)) != 0 ||
802 (r = sshbuf_put_u8(m, opts->permit_pty_flag)) != 0 ||
803 (r = sshbuf_put_u8(m, opts->permit_user_rc)) != 0 ||
804 (r = sshbuf_put_u8(m, opts->restricted)) != 0 ||
805 (r = sshbuf_put_u8(m, opts->cert_authority)) != 0 ||
806 (r = sshbuf_put_u8(m, opts->no_require_user_presence)) != 0 ||
807 (r = sshbuf_put_u8(m, opts->require_verify)) != 0)
808 return r;
809
810 /* Simple integer options */
811 if ((r = sshbuf_put_u64(m, opts->valid_before)) != 0)
812 return r;
813
814 /* tunnel number can be negative to indicate "unset" */
815 if ((r = sshbuf_put_u8(m, opts->force_tun_device == -1)) != 0 ||
816 (r = sshbuf_put_u32(m, (opts->force_tun_device < 0) ?
817 0 : (u_int)opts->force_tun_device)) != 0)
818 return r;
819
820 /* String options; these may be NULL */
821 if ((r = serialise_nullable_string(m,
822 untrusted ? "yes" : opts->cert_principals)) != 0 ||
823 (r = serialise_nullable_string(m,
824 untrusted ? "true" : opts->force_command)) != 0 ||
825 (r = serialise_nullable_string(m,
826 untrusted ? NULL : opts->required_from_host_cert)) != 0 ||
827 (r = serialise_nullable_string(m,
828 untrusted ? NULL : opts->required_from_host_keys)) != 0)
829 return r;
830
831 /* Array options */
832 if ((r = serialise_array(m, opts->env,
833 untrusted ? 0 : opts->nenv)) != 0 ||
834 (r = serialise_array(m, opts->permitopen,
835 untrusted ? 0 : opts->npermitopen)) != 0 ||
836 (r = serialise_array(m, opts->permitlisten,
837 untrusted ? 0 : opts->npermitlisten)) != 0)
838 return r;
839
840 /* success */
841 return 0;
842 }
843
844 int
sshauthopt_deserialise(struct sshbuf * m,struct sshauthopt ** optsp)845 sshauthopt_deserialise(struct sshbuf *m, struct sshauthopt **optsp)
846 {
847 struct sshauthopt *opts = NULL;
848 int r = SSH_ERR_INTERNAL_ERROR;
849 u_char f;
850 u_int tmp;
851
852 if ((opts = calloc(1, sizeof(*opts))) == NULL)
853 return SSH_ERR_ALLOC_FAIL;
854
855 /* Flag options */
856 #define OPT_FLAG(x) \
857 do { \
858 if ((r = sshbuf_get_u8(m, &f)) != 0) \
859 goto out; \
860 opts->x = f; \
861 } while (0)
862 OPT_FLAG(permit_port_forwarding_flag);
863 OPT_FLAG(permit_agent_forwarding_flag);
864 OPT_FLAG(permit_x11_forwarding_flag);
865 OPT_FLAG(permit_pty_flag);
866 OPT_FLAG(permit_user_rc);
867 OPT_FLAG(restricted);
868 OPT_FLAG(cert_authority);
869 OPT_FLAG(no_require_user_presence);
870 OPT_FLAG(require_verify);
871 #undef OPT_FLAG
872
873 /* Simple integer options */
874 if ((r = sshbuf_get_u64(m, &opts->valid_before)) != 0)
875 goto out;
876
877 /* tunnel number can be negative to indicate "unset" */
878 if ((r = sshbuf_get_u8(m, &f)) != 0 ||
879 (r = sshbuf_get_u32(m, &tmp)) != 0)
880 goto out;
881 opts->force_tun_device = f ? -1 : (int)tmp;
882
883 /* String options may be NULL */
884 if ((r = deserialise_nullable_string(m, &opts->cert_principals)) != 0 ||
885 (r = deserialise_nullable_string(m, &opts->force_command)) != 0 ||
886 (r = deserialise_nullable_string(m,
887 &opts->required_from_host_cert)) != 0 ||
888 (r = deserialise_nullable_string(m,
889 &opts->required_from_host_keys)) != 0)
890 goto out;
891
892 /* Array options */
893 if ((r = deserialise_array(m, &opts->env, &opts->nenv)) != 0 ||
894 (r = deserialise_array(m,
895 &opts->permitopen, &opts->npermitopen)) != 0 ||
896 (r = deserialise_array(m,
897 &opts->permitlisten, &opts->npermitlisten)) != 0)
898 goto out;
899
900 /* success */
901 r = 0;
902 *optsp = opts;
903 opts = NULL;
904 out:
905 sshauthopt_free(opts);
906 return r;
907 }
908