xref: /freebsd/crypto/openssh/auth-options.c (revision 093cf790569775b80662926efea6d9d3464bde94)
1 /* $OpenBSD: auth-options.c,v 1.97 2021/07/24 01:55:19 djm 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 "includes.h"
19 
20 #include <sys/types.h>
21 
22 #include <stdlib.h>
23 #include <netdb.h>
24 #include <pwd.h>
25 #include <string.h>
26 #include <stdio.h>
27 #include <stdarg.h>
28 #include <ctype.h>
29 #include <limits.h>
30 
31 #include "openbsd-compat/sys-queue.h"
32 
33 #include "xmalloc.h"
34 #include "ssherr.h"
35 #include "log.h"
36 #include "sshbuf.h"
37 #include "misc.h"
38 #include "sshkey.h"
39 #include "match.h"
40 #include "ssh2.h"
41 #include "auth-options.h"
42 
43 static int
44 dup_strings(char ***dstp, size_t *ndstp, char **src, size_t nsrc)
45 {
46 	char **dst;
47 	size_t i, j;
48 
49 	*dstp = NULL;
50 	*ndstp = 0;
51 	if (nsrc == 0)
52 		return 0;
53 
54 	if ((dst = calloc(nsrc, sizeof(*src))) == NULL)
55 		return -1;
56 	for (i = 0; i < nsrc; i++) {
57 		if ((dst[i] = strdup(src[i])) == NULL) {
58 			for (j = 0; j < i; j++)
59 				free(dst[j]);
60 			free(dst);
61 			return -1;
62 		}
63 	}
64 	/* success */
65 	*dstp = dst;
66 	*ndstp = nsrc;
67 	return 0;
68 }
69 
70 #define OPTIONS_CRITICAL	1
71 #define OPTIONS_EXTENSIONS	2
72 static int
73 cert_option_list(struct sshauthopt *opts, struct sshbuf *oblob,
74     u_int which, int crit)
75 {
76 	char *command, *allowed;
77 	char *name = NULL;
78 	struct sshbuf *c = NULL, *data = NULL;
79 	int r, ret = -1, found;
80 
81 	if ((c = sshbuf_fromb(oblob)) == NULL) {
82 		error_f("sshbuf_fromb failed");
83 		goto out;
84 	}
85 
86 	while (sshbuf_len(c) > 0) {
87 		sshbuf_free(data);
88 		data = NULL;
89 		if ((r = sshbuf_get_cstring(c, &name, NULL)) != 0 ||
90 		    (r = sshbuf_froms(c, &data)) != 0) {
91 			error_r(r, "Unable to parse certificate options");
92 			goto out;
93 		}
94 		debug3("found certificate option \"%.100s\" len %zu",
95 		    name, sshbuf_len(data));
96 		found = 0;
97 		if ((which & OPTIONS_EXTENSIONS) != 0) {
98 			if (strcmp(name, "no-touch-required") == 0) {
99 				opts->no_require_user_presence = 1;
100 				found = 1;
101 			} else if (strcmp(name, "permit-X11-forwarding") == 0) {
102 				opts->permit_x11_forwarding_flag = 1;
103 				found = 1;
104 			} else if (strcmp(name,
105 			    "permit-agent-forwarding") == 0) {
106 				opts->permit_agent_forwarding_flag = 1;
107 				found = 1;
108 			} else if (strcmp(name,
109 			    "permit-port-forwarding") == 0) {
110 				opts->permit_port_forwarding_flag = 1;
111 				found = 1;
112 			} else if (strcmp(name, "permit-pty") == 0) {
113 				opts->permit_pty_flag = 1;
114 				found = 1;
115 			} else if (strcmp(name, "permit-user-rc") == 0) {
116 				opts->permit_user_rc = 1;
117 				found = 1;
118 			}
119 		}
120 		if (!found && (which & OPTIONS_CRITICAL) != 0) {
121 			if (strcmp(name, "verify-required") == 0) {
122 				opts->require_verify = 1;
123 				found = 1;
124 			} else if (strcmp(name, "force-command") == 0) {
125 				if ((r = sshbuf_get_cstring(data, &command,
126 				    NULL)) != 0) {
127 					error_r(r, "Unable to parse \"%s\" "
128 					    "section", name);
129 					goto out;
130 				}
131 				if (opts->force_command != NULL) {
132 					error("Certificate has multiple "
133 					    "force-command options");
134 					free(command);
135 					goto out;
136 				}
137 				opts->force_command = command;
138 				found = 1;
139 			} else if (strcmp(name, "source-address") == 0) {
140 				if ((r = sshbuf_get_cstring(data, &allowed,
141 				    NULL)) != 0) {
142 					error_r(r, "Unable to parse \"%s\" "
143 					    "section", name);
144 					goto out;
145 				}
146 				if (opts->required_from_host_cert != NULL) {
147 					error("Certificate has multiple "
148 					    "source-address options");
149 					free(allowed);
150 					goto out;
151 				}
152 				/* Check syntax */
153 				if (addr_match_cidr_list(NULL, allowed) == -1) {
154 					error("Certificate source-address "
155 					    "contents invalid");
156 					goto out;
157 				}
158 				opts->required_from_host_cert = allowed;
159 				found = 1;
160 			}
161 		}
162 
163 		if (!found) {
164 			if (crit) {
165 				error("Certificate critical option \"%s\" "
166 				    "is not supported", name);
167 				goto out;
168 			} else {
169 				logit("Certificate extension \"%s\" "
170 				    "is not supported", name);
171 			}
172 		} else if (sshbuf_len(data) != 0) {
173 			error("Certificate option \"%s\" corrupt "
174 			    "(extra data)", name);
175 			goto out;
176 		}
177 		free(name);
178 		name = NULL;
179 	}
180 	/* successfully parsed all options */
181 	ret = 0;
182 
183  out:
184 	free(name);
185 	sshbuf_free(data);
186 	sshbuf_free(c);
187 	return ret;
188 }
189 
190 struct sshauthopt *
191 sshauthopt_new(void)
192 {
193 	struct sshauthopt *ret;
194 
195 	if ((ret = calloc(1, sizeof(*ret))) == NULL)
196 		return NULL;
197 	ret->force_tun_device = -1;
198 	return ret;
199 }
200 
201 void
202 sshauthopt_free(struct sshauthopt *opts)
203 {
204 	size_t i;
205 
206 	if (opts == NULL)
207 		return;
208 
209 	free(opts->cert_principals);
210 	free(opts->force_command);
211 	free(opts->required_from_host_cert);
212 	free(opts->required_from_host_keys);
213 
214 	for (i = 0; i < opts->nenv; i++)
215 		free(opts->env[i]);
216 	free(opts->env);
217 
218 	for (i = 0; i < opts->npermitopen; i++)
219 		free(opts->permitopen[i]);
220 	free(opts->permitopen);
221 
222 	for (i = 0; i < opts->npermitlisten; i++)
223 		free(opts->permitlisten[i]);
224 	free(opts->permitlisten);
225 
226 	freezero(opts, sizeof(*opts));
227 }
228 
229 struct sshauthopt *
230 sshauthopt_new_with_keys_defaults(void)
231 {
232 	struct sshauthopt *ret = NULL;
233 
234 	if ((ret = sshauthopt_new()) == NULL)
235 		return NULL;
236 
237 	/* Defaults for authorized_keys flags */
238 	ret->permit_port_forwarding_flag = 1;
239 	ret->permit_agent_forwarding_flag = 1;
240 	ret->permit_x11_forwarding_flag = 1;
241 	ret->permit_pty_flag = 1;
242 	ret->permit_user_rc = 1;
243 	return ret;
244 }
245 
246 /*
247  * Parse and record a permitopen/permitlisten directive.
248  * Return 0 on success. Return -1 on failure and sets *errstrp to error reason.
249  */
250 static int
251 handle_permit(const char **optsp, int allow_bare_port,
252     char ***permitsp, size_t *npermitsp, const char **errstrp)
253 {
254 	char *opt, *tmp, *cp, *host, **permits = *permitsp;
255 	size_t npermits = *npermitsp;
256 	const char *errstr = "unknown error";
257 
258 	if (npermits > SSH_AUTHOPT_PERMIT_MAX) {
259 		*errstrp = "too many permission directives";
260 		return -1;
261 	}
262 	if ((opt = opt_dequote(optsp, &errstr)) == NULL) {
263 		return -1;
264 	}
265 	if (allow_bare_port && strchr(opt, ':') == NULL) {
266 		/*
267 		 * Allow a bare port number in permitlisten to indicate a
268 		 * listen_host wildcard.
269 		 */
270 		if (asprintf(&tmp, "*:%s", opt) == -1) {
271 			free(opt);
272 			*errstrp = "memory allocation failed";
273 			return -1;
274 		}
275 		free(opt);
276 		opt = tmp;
277 	}
278 	if ((tmp = strdup(opt)) == NULL) {
279 		free(opt);
280 		*errstrp = "memory allocation failed";
281 		return -1;
282 	}
283 	cp = tmp;
284 	/* validate syntax before recording it. */
285 	host = hpdelim(&cp);
286 	if (host == NULL || strlen(host) >= NI_MAXHOST) {
287 		free(tmp);
288 		free(opt);
289 		*errstrp = "invalid permission hostname";
290 		return -1;
291 	}
292 	/*
293 	 * don't want to use permitopen_port to avoid
294 	 * dependency on channels.[ch] here.
295 	 */
296 	if (cp == NULL ||
297 	    (strcmp(cp, "*") != 0 && a2port(cp) <= 0)) {
298 		free(tmp);
299 		free(opt);
300 		*errstrp = "invalid permission port";
301 		return -1;
302 	}
303 	/* XXX - add streamlocal support */
304 	free(tmp);
305 	/* Record it */
306 	if ((permits = recallocarray(permits, npermits, npermits + 1,
307 	    sizeof(*permits))) == NULL) {
308 		free(opt);
309 		/* NB. don't update *permitsp if alloc fails */
310 		*errstrp = "memory allocation failed";
311 		return -1;
312 	}
313 	permits[npermits++] = opt;
314 	*permitsp = permits;
315 	*npermitsp = npermits;
316 	return 0;
317 }
318 
319 struct sshauthopt *
320 sshauthopt_parse(const char *opts, const char **errstrp)
321 {
322 	char **oarray, *opt, *cp, *tmp;
323 	int r;
324 	struct sshauthopt *ret = NULL;
325 	const char *errstr = "unknown error";
326 	uint64_t valid_before;
327 	size_t i, l;
328 
329 	if (errstrp != NULL)
330 		*errstrp = NULL;
331 	if ((ret = sshauthopt_new_with_keys_defaults()) == NULL)
332 		goto alloc_fail;
333 
334 	if (opts == NULL)
335 		return ret;
336 
337 	while (*opts && *opts != ' ' && *opts != '\t') {
338 		/* flag options */
339 		if ((r = opt_flag("restrict", 0, &opts)) != -1) {
340 			ret->restricted = 1;
341 			ret->permit_port_forwarding_flag = 0;
342 			ret->permit_agent_forwarding_flag = 0;
343 			ret->permit_x11_forwarding_flag = 0;
344 			ret->permit_pty_flag = 0;
345 			ret->permit_user_rc = 0;
346 		} else if ((r = opt_flag("cert-authority", 0, &opts)) != -1) {
347 			ret->cert_authority = r;
348 		} else if ((r = opt_flag("port-forwarding", 1, &opts)) != -1) {
349 			ret->permit_port_forwarding_flag = r == 1;
350 		} else if ((r = opt_flag("agent-forwarding", 1, &opts)) != -1) {
351 			ret->permit_agent_forwarding_flag = r == 1;
352 		} else if ((r = opt_flag("x11-forwarding", 1, &opts)) != -1) {
353 			ret->permit_x11_forwarding_flag = r == 1;
354 		} else if ((r = opt_flag("touch-required", 1, &opts)) != -1) {
355 			ret->no_require_user_presence = r != 1; /* NB. flip */
356 		} else if ((r = opt_flag("verify-required", 1, &opts)) != -1) {
357 			ret->require_verify = r == 1;
358 		} else if ((r = opt_flag("pty", 1, &opts)) != -1) {
359 			ret->permit_pty_flag = r == 1;
360 		} else if ((r = opt_flag("user-rc", 1, &opts)) != -1) {
361 			ret->permit_user_rc = r == 1;
362 		} else if (opt_match(&opts, "command")) {
363 			if (ret->force_command != NULL) {
364 				errstr = "multiple \"command\" clauses";
365 				goto fail;
366 			}
367 			ret->force_command = opt_dequote(&opts, &errstr);
368 			if (ret->force_command == NULL)
369 				goto fail;
370 		} else if (opt_match(&opts, "principals")) {
371 			if (ret->cert_principals != NULL) {
372 				errstr = "multiple \"principals\" clauses";
373 				goto fail;
374 			}
375 			ret->cert_principals = opt_dequote(&opts, &errstr);
376 			if (ret->cert_principals == NULL)
377 				goto fail;
378 		} else if (opt_match(&opts, "from")) {
379 			if (ret->required_from_host_keys != NULL) {
380 				errstr = "multiple \"from\" clauses";
381 				goto fail;
382 			}
383 			ret->required_from_host_keys = opt_dequote(&opts,
384 			    &errstr);
385 			if (ret->required_from_host_keys == NULL)
386 				goto fail;
387 		} else if (opt_match(&opts, "expiry-time")) {
388 			if ((opt = opt_dequote(&opts, &errstr)) == NULL)
389 				goto fail;
390 			if (parse_absolute_time(opt, &valid_before) != 0 ||
391 			    valid_before == 0) {
392 				free(opt);
393 				errstr = "invalid expires time";
394 				goto fail;
395 			}
396 			free(opt);
397 			if (ret->valid_before == 0 ||
398 			    valid_before < ret->valid_before)
399 				ret->valid_before = valid_before;
400 		} else if (opt_match(&opts, "environment")) {
401 			if (ret->nenv > SSH_AUTHOPT_ENV_MAX) {
402 				errstr = "too many environment strings";
403 				goto fail;
404 			}
405 			if ((opt = opt_dequote(&opts, &errstr)) == NULL)
406 				goto fail;
407 			/* env name must be alphanumeric and followed by '=' */
408 			if ((tmp = strchr(opt, '=')) == NULL) {
409 				free(opt);
410 				errstr = "invalid environment string";
411 				goto fail;
412 			}
413 			if ((cp = strdup(opt)) == NULL) {
414 				free(opt);
415 				goto alloc_fail;
416 			}
417 			l = (size_t)(tmp - opt);
418 			cp[l] = '\0'; /* truncate at '=' */
419 			if (!valid_env_name(cp)) {
420 				free(cp);
421 				free(opt);
422 				errstr = "invalid environment string";
423 				goto fail;
424 			}
425 			/* Check for duplicates; XXX O(n*log(n)) */
426 			for (i = 0; i < ret->nenv; i++) {
427 				if (strncmp(ret->env[i], cp, l) == 0 &&
428 				    ret->env[i][l] == '=')
429 					break;
430 			}
431 			free(cp);
432 			/* First match wins */
433 			if (i >= ret->nenv) {
434 				/* Append it. */
435 				oarray = ret->env;
436 				if ((ret->env = recallocarray(ret->env,
437 				    ret->nenv, ret->nenv + 1,
438 				    sizeof(*ret->env))) == NULL) {
439 					free(opt);
440 					/* put it back for cleanup */
441 					ret->env = oarray;
442 					goto alloc_fail;
443 				}
444 				ret->env[ret->nenv++] = opt;
445 				opt = NULL; /* transferred */
446 			}
447 			free(opt);
448 		} else if (opt_match(&opts, "permitopen")) {
449 			if (handle_permit(&opts, 0, &ret->permitopen,
450 			    &ret->npermitopen, &errstr) != 0)
451 				goto fail;
452 		} else if (opt_match(&opts, "permitlisten")) {
453 			if (handle_permit(&opts, 1, &ret->permitlisten,
454 			    &ret->npermitlisten, &errstr) != 0)
455 				goto fail;
456 		} else if (opt_match(&opts, "tunnel")) {
457 			if ((opt = opt_dequote(&opts, &errstr)) == NULL)
458 				goto fail;
459 			ret->force_tun_device = a2tun(opt, NULL);
460 			free(opt);
461 			if (ret->force_tun_device == SSH_TUNID_ERR) {
462 				errstr = "invalid tun device";
463 				goto fail;
464 			}
465 		}
466 		/*
467 		 * Skip the comma, and move to the next option
468 		 * (or break out if there are no more).
469 		 */
470 		if (*opts == '\0' || *opts == ' ' || *opts == '\t')
471 			break;		/* End of options. */
472 		/* Anything other than a comma is an unknown option */
473 		if (*opts != ',') {
474 			errstr = "unknown key option";
475 			goto fail;
476 		}
477 		opts++;
478 		if (*opts == '\0') {
479 			errstr = "unexpected end-of-options";
480 			goto fail;
481 		}
482 	}
483 
484 	/* success */
485 	if (errstrp != NULL)
486 		*errstrp = NULL;
487 	return ret;
488 
489 alloc_fail:
490 	errstr = "memory allocation failed";
491 fail:
492 	sshauthopt_free(ret);
493 	if (errstrp != NULL)
494 		*errstrp = errstr;
495 	return NULL;
496 }
497 
498 struct sshauthopt *
499 sshauthopt_from_cert(struct sshkey *k)
500 {
501 	struct sshauthopt *ret;
502 
503 	if (k == NULL || !sshkey_type_is_cert(k->type) || k->cert == NULL ||
504 	    k->cert->type != SSH2_CERT_TYPE_USER)
505 		return NULL;
506 
507 	if ((ret = sshauthopt_new()) == NULL)
508 		return NULL;
509 
510 	/* Handle options and critical extensions separately */
511 	if (cert_option_list(ret, k->cert->critical,
512 	    OPTIONS_CRITICAL, 1) == -1) {
513 		sshauthopt_free(ret);
514 		return NULL;
515 	}
516 	if (cert_option_list(ret, k->cert->extensions,
517 	    OPTIONS_EXTENSIONS, 0) == -1) {
518 		sshauthopt_free(ret);
519 		return NULL;
520 	}
521 	/* success */
522 	return ret;
523 }
524 
525 /*
526  * Merges "additional" options to "primary" and returns the result.
527  * NB. Some options from primary have primacy.
528  */
529 struct sshauthopt *
530 sshauthopt_merge(const struct sshauthopt *primary,
531     const struct sshauthopt *additional, const char **errstrp)
532 {
533 	struct sshauthopt *ret;
534 	const char *errstr = "internal error";
535 	const char *tmp;
536 
537 	if (errstrp != NULL)
538 		*errstrp = NULL;
539 
540 	if ((ret = sshauthopt_new()) == NULL)
541 		goto alloc_fail;
542 
543 	/* cert_authority and cert_principals are cleared in result */
544 
545 	/* Prefer access lists from primary. */
546 	/* XXX err is both set and mismatch? */
547 	tmp = primary->required_from_host_cert;
548 	if (tmp == NULL)
549 		tmp = additional->required_from_host_cert;
550 	if (tmp != NULL && (ret->required_from_host_cert = strdup(tmp)) == NULL)
551 		goto alloc_fail;
552 	tmp = primary->required_from_host_keys;
553 	if (tmp == NULL)
554 		tmp = additional->required_from_host_keys;
555 	if (tmp != NULL && (ret->required_from_host_keys = strdup(tmp)) == NULL)
556 		goto alloc_fail;
557 
558 	/*
559 	 * force_tun_device, permitopen/permitlisten and environment all
560 	 * prefer the primary.
561 	 */
562 	ret->force_tun_device = primary->force_tun_device;
563 	if (ret->force_tun_device == -1)
564 		ret->force_tun_device = additional->force_tun_device;
565 	if (primary->nenv > 0) {
566 		if (dup_strings(&ret->env, &ret->nenv,
567 		    primary->env, primary->nenv) != 0)
568 			goto alloc_fail;
569 	} else if (additional->nenv) {
570 		if (dup_strings(&ret->env, &ret->nenv,
571 		    additional->env, additional->nenv) != 0)
572 			goto alloc_fail;
573 	}
574 	if (primary->npermitopen > 0) {
575 		if (dup_strings(&ret->permitopen, &ret->npermitopen,
576 		    primary->permitopen, primary->npermitopen) != 0)
577 			goto alloc_fail;
578 	} else if (additional->npermitopen > 0) {
579 		if (dup_strings(&ret->permitopen, &ret->npermitopen,
580 		    additional->permitopen, additional->npermitopen) != 0)
581 			goto alloc_fail;
582 	}
583 
584 	if (primary->npermitlisten > 0) {
585 		if (dup_strings(&ret->permitlisten, &ret->npermitlisten,
586 		    primary->permitlisten, primary->npermitlisten) != 0)
587 			goto alloc_fail;
588 	} else if (additional->npermitlisten > 0) {
589 		if (dup_strings(&ret->permitlisten, &ret->npermitlisten,
590 		    additional->permitlisten, additional->npermitlisten) != 0)
591 			goto alloc_fail;
592 	}
593 
594 #define OPTFLAG_AND(x) ret->x = (primary->x == 1) && (additional->x == 1)
595 #define OPTFLAG_OR(x) ret->x = (primary->x == 1) || (additional->x == 1)
596 	/* Permissive flags are logical-AND (i.e. must be set in both) */
597 	OPTFLAG_AND(permit_port_forwarding_flag);
598 	OPTFLAG_AND(permit_agent_forwarding_flag);
599 	OPTFLAG_AND(permit_x11_forwarding_flag);
600 	OPTFLAG_AND(permit_pty_flag);
601 	OPTFLAG_AND(permit_user_rc);
602 	OPTFLAG_AND(no_require_user_presence);
603 	/* Restrictive flags are logical-OR (i.e. must be set in either) */
604 	OPTFLAG_OR(require_verify);
605 #undef OPTFLAG_AND
606 
607 	/* Earliest expiry time should win */
608 	if (primary->valid_before != 0)
609 		ret->valid_before = primary->valid_before;
610 	if (additional->valid_before != 0 &&
611 	    additional->valid_before < ret->valid_before)
612 		ret->valid_before = additional->valid_before;
613 
614 	/*
615 	 * When both multiple forced-command are specified, only
616 	 * proceed if they are identical, otherwise fail.
617 	 */
618 	if (primary->force_command != NULL &&
619 	    additional->force_command != NULL) {
620 		if (strcmp(primary->force_command,
621 		    additional->force_command) == 0) {
622 			/* ok */
623 			ret->force_command = strdup(primary->force_command);
624 			if (ret->force_command == NULL)
625 				goto alloc_fail;
626 		} else {
627 			errstr = "forced command options do not match";
628 			goto fail;
629 		}
630 	} else if (primary->force_command != NULL) {
631 		if ((ret->force_command = strdup(
632 		    primary->force_command)) == NULL)
633 			goto alloc_fail;
634 	} else if (additional->force_command != NULL) {
635 		if ((ret->force_command = strdup(
636 		    additional->force_command)) == NULL)
637 			goto alloc_fail;
638 	}
639 	/* success */
640 	if (errstrp != NULL)
641 		*errstrp = NULL;
642 	return ret;
643 
644  alloc_fail:
645 	errstr = "memory allocation failed";
646  fail:
647 	if (errstrp != NULL)
648 		*errstrp = errstr;
649 	sshauthopt_free(ret);
650 	return NULL;
651 }
652 
653 /*
654  * Copy options
655  */
656 struct sshauthopt *
657 sshauthopt_copy(const struct sshauthopt *orig)
658 {
659 	struct sshauthopt *ret;
660 
661 	if ((ret = sshauthopt_new()) == NULL)
662 		return NULL;
663 
664 #define OPTSCALAR(x) ret->x = orig->x
665 	OPTSCALAR(permit_port_forwarding_flag);
666 	OPTSCALAR(permit_agent_forwarding_flag);
667 	OPTSCALAR(permit_x11_forwarding_flag);
668 	OPTSCALAR(permit_pty_flag);
669 	OPTSCALAR(permit_user_rc);
670 	OPTSCALAR(restricted);
671 	OPTSCALAR(cert_authority);
672 	OPTSCALAR(force_tun_device);
673 	OPTSCALAR(valid_before);
674 	OPTSCALAR(no_require_user_presence);
675 	OPTSCALAR(require_verify);
676 #undef OPTSCALAR
677 #define OPTSTRING(x) \
678 	do { \
679 		if (orig->x != NULL && (ret->x = strdup(orig->x)) == NULL) { \
680 			sshauthopt_free(ret); \
681 			return NULL; \
682 		} \
683 	} while (0)
684 	OPTSTRING(cert_principals);
685 	OPTSTRING(force_command);
686 	OPTSTRING(required_from_host_cert);
687 	OPTSTRING(required_from_host_keys);
688 #undef OPTSTRING
689 
690 	if (dup_strings(&ret->env, &ret->nenv, orig->env, orig->nenv) != 0 ||
691 	    dup_strings(&ret->permitopen, &ret->npermitopen,
692 	    orig->permitopen, orig->npermitopen) != 0 ||
693 	    dup_strings(&ret->permitlisten, &ret->npermitlisten,
694 	    orig->permitlisten, orig->npermitlisten) != 0) {
695 		sshauthopt_free(ret);
696 		return NULL;
697 	}
698 	return ret;
699 }
700 
701 static int
702 serialise_array(struct sshbuf *m, char **a, size_t n)
703 {
704 	struct sshbuf *b;
705 	size_t i;
706 	int r;
707 
708 	if (n > INT_MAX)
709 		return SSH_ERR_INTERNAL_ERROR;
710 
711 	if ((b = sshbuf_new()) == NULL) {
712 		return SSH_ERR_ALLOC_FAIL;
713 	}
714 	for (i = 0; i < n; i++) {
715 		if ((r = sshbuf_put_cstring(b, a[i])) != 0) {
716 			sshbuf_free(b);
717 			return r;
718 		}
719 	}
720 	if ((r = sshbuf_put_u32(m, n)) != 0 ||
721 	    (r = sshbuf_put_stringb(m, b)) != 0) {
722 		sshbuf_free(b);
723 		return r;
724 	}
725 	/* success */
726 	return 0;
727 }
728 
729 static int
730 deserialise_array(struct sshbuf *m, char ***ap, size_t *np)
731 {
732 	char **a = NULL;
733 	size_t i, n = 0;
734 	struct sshbuf *b = NULL;
735 	u_int tmp;
736 	int r = SSH_ERR_INTERNAL_ERROR;
737 
738 	if ((r = sshbuf_get_u32(m, &tmp)) != 0 ||
739 	    (r = sshbuf_froms(m, &b)) != 0)
740 		goto out;
741 	if (tmp > INT_MAX) {
742 		r = SSH_ERR_INVALID_FORMAT;
743 		goto out;
744 	}
745 	n = tmp;
746 	if (n > 0 && (a = calloc(n, sizeof(*a))) == NULL) {
747 		r = SSH_ERR_ALLOC_FAIL;
748 		goto out;
749 	}
750 	for (i = 0; i < n; i++) {
751 		if ((r = sshbuf_get_cstring(b, &a[i], NULL)) != 0)
752 			goto out;
753 	}
754 	/* success */
755 	r = 0;
756 	*ap = a;
757 	a = NULL;
758 	*np = n;
759 	n = 0;
760  out:
761 	if (a != NULL) {
762 		for (i = 0; i < n; i++)
763 			free(a[i]);
764 		free(a);
765 	}
766 	sshbuf_free(b);
767 	return r;
768 }
769 
770 static int
771 serialise_nullable_string(struct sshbuf *m, const char *s)
772 {
773 	int r;
774 
775 	if ((r = sshbuf_put_u8(m, s == NULL)) != 0 ||
776 	    (r = sshbuf_put_cstring(m, s)) != 0)
777 		return r;
778 	return 0;
779 }
780 
781 static int
782 deserialise_nullable_string(struct sshbuf *m, char **sp)
783 {
784 	int r;
785 	u_char flag;
786 
787 	*sp = NULL;
788 	if ((r = sshbuf_get_u8(m, &flag)) != 0 ||
789 	    (r = sshbuf_get_cstring(m, flag ? NULL : sp, NULL)) != 0)
790 		return r;
791 	return 0;
792 }
793 
794 int
795 sshauthopt_serialise(const struct sshauthopt *opts, struct sshbuf *m,
796     int untrusted)
797 {
798 	int r = SSH_ERR_INTERNAL_ERROR;
799 
800 	/* Flag options */
801 	if ((r = sshbuf_put_u8(m, opts->permit_port_forwarding_flag)) != 0 ||
802 	    (r = sshbuf_put_u8(m, opts->permit_agent_forwarding_flag)) != 0 ||
803 	    (r = sshbuf_put_u8(m, opts->permit_x11_forwarding_flag)) != 0 ||
804 	    (r = sshbuf_put_u8(m, opts->permit_pty_flag)) != 0 ||
805 	    (r = sshbuf_put_u8(m, opts->permit_user_rc)) != 0 ||
806 	    (r = sshbuf_put_u8(m, opts->restricted)) != 0 ||
807 	    (r = sshbuf_put_u8(m, opts->cert_authority)) != 0 ||
808 	    (r = sshbuf_put_u8(m, opts->no_require_user_presence)) != 0 ||
809 	    (r = sshbuf_put_u8(m, opts->require_verify)) != 0)
810 		return r;
811 
812 	/* Simple integer options */
813 	if ((r = sshbuf_put_u64(m, opts->valid_before)) != 0)
814 		return r;
815 
816 	/* tunnel number can be negative to indicate "unset" */
817 	if ((r = sshbuf_put_u8(m, opts->force_tun_device == -1)) != 0 ||
818 	    (r = sshbuf_put_u32(m, (opts->force_tun_device < 0) ?
819 	    0 : (u_int)opts->force_tun_device)) != 0)
820 		return r;
821 
822 	/* String options; these may be NULL */
823 	if ((r = serialise_nullable_string(m,
824 	    untrusted ? "yes" : opts->cert_principals)) != 0 ||
825 	    (r = serialise_nullable_string(m,
826 	    untrusted ? "true" : opts->force_command)) != 0 ||
827 	    (r = serialise_nullable_string(m,
828 	    untrusted ? NULL : opts->required_from_host_cert)) != 0 ||
829 	    (r = serialise_nullable_string(m,
830 	    untrusted ? NULL : opts->required_from_host_keys)) != 0)
831 		return r;
832 
833 	/* Array options */
834 	if ((r = serialise_array(m, opts->env,
835 	    untrusted ? 0 : opts->nenv)) != 0 ||
836 	    (r = serialise_array(m, opts->permitopen,
837 	    untrusted ? 0 : opts->npermitopen)) != 0 ||
838 	    (r = serialise_array(m, opts->permitlisten,
839 	    untrusted ? 0 : opts->npermitlisten)) != 0)
840 		return r;
841 
842 	/* success */
843 	return 0;
844 }
845 
846 int
847 sshauthopt_deserialise(struct sshbuf *m, struct sshauthopt **optsp)
848 {
849 	struct sshauthopt *opts = NULL;
850 	int r = SSH_ERR_INTERNAL_ERROR;
851 	u_char f;
852 	u_int tmp;
853 
854 	if ((opts = calloc(1, sizeof(*opts))) == NULL)
855 		return SSH_ERR_ALLOC_FAIL;
856 
857 	/* Flag options */
858 #define OPT_FLAG(x) \
859 	do { \
860 		if ((r = sshbuf_get_u8(m, &f)) != 0) \
861 			goto out; \
862 		opts->x = f; \
863 	} while (0)
864 	OPT_FLAG(permit_port_forwarding_flag);
865 	OPT_FLAG(permit_agent_forwarding_flag);
866 	OPT_FLAG(permit_x11_forwarding_flag);
867 	OPT_FLAG(permit_pty_flag);
868 	OPT_FLAG(permit_user_rc);
869 	OPT_FLAG(restricted);
870 	OPT_FLAG(cert_authority);
871 	OPT_FLAG(no_require_user_presence);
872 	OPT_FLAG(require_verify);
873 #undef OPT_FLAG
874 
875 	/* Simple integer options */
876 	if ((r = sshbuf_get_u64(m, &opts->valid_before)) != 0)
877 		goto out;
878 
879 	/* tunnel number can be negative to indicate "unset" */
880 	if ((r = sshbuf_get_u8(m, &f)) != 0 ||
881 	    (r = sshbuf_get_u32(m, &tmp)) != 0)
882 		goto out;
883 	opts->force_tun_device = f ? -1 : (int)tmp;
884 
885 	/* String options may be NULL */
886 	if ((r = deserialise_nullable_string(m, &opts->cert_principals)) != 0 ||
887 	    (r = deserialise_nullable_string(m, &opts->force_command)) != 0 ||
888 	    (r = deserialise_nullable_string(m,
889 	    &opts->required_from_host_cert)) != 0 ||
890 	    (r = deserialise_nullable_string(m,
891 	    &opts->required_from_host_keys)) != 0)
892 		goto out;
893 
894 	/* Array options */
895 	if ((r = deserialise_array(m, &opts->env, &opts->nenv)) != 0 ||
896 	    (r = deserialise_array(m,
897 	    &opts->permitopen, &opts->npermitopen)) != 0 ||
898 	    (r = deserialise_array(m,
899 	    &opts->permitlisten, &opts->npermitlisten)) != 0)
900 		goto out;
901 
902 	/* success */
903 	r = 0;
904 	*optsp = opts;
905 	opts = NULL;
906  out:
907 	sshauthopt_free(opts);
908 	return r;
909 }
910