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 "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#ifdef HAVE_STDINT_H
28# include <stdint.h>
29#endif
30#include <stdarg.h>
31#include <ctype.h>
32#include <limits.h>
33
34#include "openbsd-compat/sys-queue.h"
35
36#include "xmalloc.h"
37#include "ssherr.h"
38#include "log.h"
39#include "sshbuf.h"
40#include "misc.h"
41#include "sshkey.h"
42#include "match.h"
43#include "ssh2.h"
44#include "auth-options.h"
45
46static int
47dup_strings(char ***dstp, size_t *ndstp, char **src, size_t nsrc)
48{
49	char **dst;
50	size_t i, j;
51
52	*dstp = NULL;
53	*ndstp = 0;
54
55	if (nsrc == 0)
56		return 0;
57	if (nsrc >= SIZE_MAX / sizeof(*src) ||
58	    (dst = calloc(nsrc, sizeof(*src))) == NULL)
59		return -1;
60	for (i = 0; i < nsrc; i++) {
61		if ((dst[i] = strdup(src[i])) == NULL) {
62			for (j = 0; j < i; j++)
63				free(dst[j]);
64			free(dst);
65			return -1;
66		}
67	}
68	/* success */
69	*dstp = dst;
70	*ndstp = nsrc;
71	return 0;
72}
73
74#define OPTIONS_CRITICAL	1
75#define OPTIONS_EXTENSIONS	2
76static int
77cert_option_list(struct sshauthopt *opts, struct sshbuf *oblob,
78    u_int which, int crit)
79{
80	char *command, *allowed;
81	char *name = NULL;
82	struct sshbuf *c = NULL, *data = NULL;
83	int r, ret = -1, found;
84
85	if ((c = sshbuf_fromb(oblob)) == NULL) {
86		error_f("sshbuf_fromb failed");
87		goto out;
88	}
89
90	while (sshbuf_len(c) > 0) {
91		sshbuf_free(data);
92		data = NULL;
93		if ((r = sshbuf_get_cstring(c, &name, NULL)) != 0 ||
94		    (r = sshbuf_froms(c, &data)) != 0) {
95			error_r(r, "Unable to parse certificate options");
96			goto out;
97		}
98		debug3("found certificate option \"%.100s\" len %zu",
99		    name, sshbuf_len(data));
100		found = 0;
101		if ((which & OPTIONS_EXTENSIONS) != 0) {
102			if (strcmp(name, "no-touch-required") == 0) {
103				opts->no_require_user_presence = 1;
104				found = 1;
105			} else if (strcmp(name, "permit-X11-forwarding") == 0) {
106				opts->permit_x11_forwarding_flag = 1;
107				found = 1;
108			} else if (strcmp(name,
109			    "permit-agent-forwarding") == 0) {
110				opts->permit_agent_forwarding_flag = 1;
111				found = 1;
112			} else if (strcmp(name,
113			    "permit-port-forwarding") == 0) {
114				opts->permit_port_forwarding_flag = 1;
115				found = 1;
116			} else if (strcmp(name, "permit-pty") == 0) {
117				opts->permit_pty_flag = 1;
118				found = 1;
119			} else if (strcmp(name, "permit-user-rc") == 0) {
120				opts->permit_user_rc = 1;
121				found = 1;
122			}
123		}
124		if (!found && (which & OPTIONS_CRITICAL) != 0) {
125			if (strcmp(name, "verify-required") == 0) {
126				opts->require_verify = 1;
127				found = 1;
128			} else if (strcmp(name, "force-command") == 0) {
129				if ((r = sshbuf_get_cstring(data, &command,
130				    NULL)) != 0) {
131					error_r(r, "Unable to parse \"%s\" "
132					    "section", name);
133					goto out;
134				}
135				if (opts->force_command != NULL) {
136					error("Certificate has multiple "
137					    "force-command options");
138					free(command);
139					goto out;
140				}
141				opts->force_command = command;
142				found = 1;
143			} else if (strcmp(name, "source-address") == 0) {
144				if ((r = sshbuf_get_cstring(data, &allowed,
145				    NULL)) != 0) {
146					error_r(r, "Unable to parse \"%s\" "
147					    "section", name);
148					goto out;
149				}
150				if (opts->required_from_host_cert != NULL) {
151					error("Certificate has multiple "
152					    "source-address options");
153					free(allowed);
154					goto out;
155				}
156				/* Check syntax */
157				if (addr_match_cidr_list(NULL, allowed) == -1) {
158					error("Certificate source-address "
159					    "contents invalid");
160					goto out;
161				}
162				opts->required_from_host_cert = allowed;
163				found = 1;
164			}
165		}
166
167		if (!found) {
168			if (crit) {
169				error("Certificate critical option \"%s\" "
170				    "is not supported", name);
171				goto out;
172			} else {
173				logit("Certificate extension \"%s\" "
174				    "is not supported", name);
175			}
176		} else if (sshbuf_len(data) != 0) {
177			error("Certificate option \"%s\" corrupt "
178			    "(extra data)", name);
179			goto out;
180		}
181		free(name);
182		name = NULL;
183	}
184	/* successfully parsed all options */
185	ret = 0;
186
187 out:
188	free(name);
189	sshbuf_free(data);
190	sshbuf_free(c);
191	return ret;
192}
193
194struct sshauthopt *
195sshauthopt_new(void)
196{
197	struct sshauthopt *ret;
198
199	if ((ret = calloc(1, sizeof(*ret))) == NULL)
200		return NULL;
201	ret->force_tun_device = -1;
202	return ret;
203}
204
205void
206sshauthopt_free(struct sshauthopt *opts)
207{
208	size_t i;
209
210	if (opts == NULL)
211		return;
212
213	free(opts->cert_principals);
214	free(opts->force_command);
215	free(opts->required_from_host_cert);
216	free(opts->required_from_host_keys);
217
218	for (i = 0; i < opts->nenv; i++)
219		free(opts->env[i]);
220	free(opts->env);
221
222	for (i = 0; i < opts->npermitopen; i++)
223		free(opts->permitopen[i]);
224	free(opts->permitopen);
225
226	for (i = 0; i < opts->npermitlisten; i++)
227		free(opts->permitlisten[i]);
228	free(opts->permitlisten);
229
230	freezero(opts, sizeof(*opts));
231}
232
233struct sshauthopt *
234sshauthopt_new_with_keys_defaults(void)
235{
236	struct sshauthopt *ret = NULL;
237
238	if ((ret = sshauthopt_new()) == NULL)
239		return NULL;
240
241	/* Defaults for authorized_keys flags */
242	ret->permit_port_forwarding_flag = 1;
243	ret->permit_agent_forwarding_flag = 1;
244	ret->permit_x11_forwarding_flag = 1;
245	ret->permit_pty_flag = 1;
246	ret->permit_user_rc = 1;
247	return ret;
248}
249
250/*
251 * Parse and record a permitopen/permitlisten directive.
252 * Return 0 on success. Return -1 on failure and sets *errstrp to error reason.
253 */
254static int
255handle_permit(const char **optsp, int allow_bare_port,
256    char ***permitsp, size_t *npermitsp, const char **errstrp)
257{
258	char *opt, *tmp, *cp, *host, **permits = *permitsp;
259	size_t npermits = *npermitsp;
260	const char *errstr = "unknown error";
261
262	if (npermits > SSH_AUTHOPT_PERMIT_MAX) {
263		*errstrp = "too many permission directives";
264		return -1;
265	}
266	if ((opt = opt_dequote(optsp, &errstr)) == NULL) {
267		return -1;
268	}
269	if (allow_bare_port && strchr(opt, ':') == NULL) {
270		/*
271		 * Allow a bare port number in permitlisten to indicate a
272		 * listen_host wildcard.
273		 */
274		if (asprintf(&tmp, "*:%s", opt) == -1) {
275			free(opt);
276			*errstrp = "memory allocation failed";
277			return -1;
278		}
279		free(opt);
280		opt = tmp;
281	}
282	if ((tmp = strdup(opt)) == NULL) {
283		free(opt);
284		*errstrp = "memory allocation failed";
285		return -1;
286	}
287	cp = tmp;
288	/* validate syntax before recording it. */
289	host = hpdelim2(&cp, NULL);
290	if (host == NULL || strlen(host) >= NI_MAXHOST) {
291		free(tmp);
292		free(opt);
293		*errstrp = "invalid permission hostname";
294		return -1;
295	}
296	/*
297	 * don't want to use permitopen_port to avoid
298	 * dependency on channels.[ch] here.
299	 */
300	if (cp == NULL ||
301	    (strcmp(cp, "*") != 0 && a2port(cp) <= 0)) {
302		free(tmp);
303		free(opt);
304		*errstrp = "invalid permission port";
305		return -1;
306	}
307	/* XXX - add streamlocal support */
308	free(tmp);
309	/* Record it */
310	if ((permits = recallocarray(permits, npermits, npermits + 1,
311	    sizeof(*permits))) == NULL) {
312		free(opt);
313		/* NB. don't update *permitsp if alloc fails */
314		*errstrp = "memory allocation failed";
315		return -1;
316	}
317	permits[npermits++] = opt;
318	*permitsp = permits;
319	*npermitsp = npermits;
320	return 0;
321}
322
323struct sshauthopt *
324sshauthopt_parse(const char *opts, const char **errstrp)
325{
326	char **oarray, *opt, *cp, *tmp;
327	int r;
328	struct sshauthopt *ret = NULL;
329	const char *errstr = "unknown error";
330	uint64_t valid_before;
331	size_t i, l;
332
333	if (errstrp != NULL)
334		*errstrp = NULL;
335	if ((ret = sshauthopt_new_with_keys_defaults()) == NULL)
336		goto alloc_fail;
337
338	if (opts == NULL)
339		return ret;
340
341	while (*opts && *opts != ' ' && *opts != '\t') {
342		/* flag options */
343		if ((r = opt_flag("restrict", 0, &opts)) != -1) {
344			ret->restricted = 1;
345			ret->permit_port_forwarding_flag = 0;
346			ret->permit_agent_forwarding_flag = 0;
347			ret->permit_x11_forwarding_flag = 0;
348			ret->permit_pty_flag = 0;
349			ret->permit_user_rc = 0;
350		} else if ((r = opt_flag("cert-authority", 0, &opts)) != -1) {
351			ret->cert_authority = r;
352		} else if ((r = opt_flag("port-forwarding", 1, &opts)) != -1) {
353			ret->permit_port_forwarding_flag = r == 1;
354		} else if ((r = opt_flag("agent-forwarding", 1, &opts)) != -1) {
355			ret->permit_agent_forwarding_flag = r == 1;
356		} else if ((r = opt_flag("x11-forwarding", 1, &opts)) != -1) {
357			ret->permit_x11_forwarding_flag = r == 1;
358		} else if ((r = opt_flag("touch-required", 1, &opts)) != -1) {
359			ret->no_require_user_presence = r != 1; /* NB. flip */
360		} else if ((r = opt_flag("verify-required", 1, &opts)) != -1) {
361			ret->require_verify = r == 1;
362		} else if ((r = opt_flag("pty", 1, &opts)) != -1) {
363			ret->permit_pty_flag = r == 1;
364		} else if ((r = opt_flag("user-rc", 1, &opts)) != -1) {
365			ret->permit_user_rc = r == 1;
366		} else if (opt_match(&opts, "command")) {
367			if (ret->force_command != NULL) {
368				errstr = "multiple \"command\" clauses";
369				goto fail;
370			}
371			ret->force_command = opt_dequote(&opts, &errstr);
372			if (ret->force_command == NULL)
373				goto fail;
374		} else if (opt_match(&opts, "principals")) {
375			if (ret->cert_principals != NULL) {
376				errstr = "multiple \"principals\" clauses";
377				goto fail;
378			}
379			ret->cert_principals = opt_dequote(&opts, &errstr);
380			if (ret->cert_principals == NULL)
381				goto fail;
382		} else if (opt_match(&opts, "from")) {
383			if (ret->required_from_host_keys != NULL) {
384				errstr = "multiple \"from\" clauses";
385				goto fail;
386			}
387			ret->required_from_host_keys = opt_dequote(&opts,
388			    &errstr);
389			if (ret->required_from_host_keys == NULL)
390				goto fail;
391		} else if (opt_match(&opts, "expiry-time")) {
392			if ((opt = opt_dequote(&opts, &errstr)) == NULL)
393				goto fail;
394			if (parse_absolute_time(opt, &valid_before) != 0 ||
395			    valid_before == 0) {
396				free(opt);
397				errstr = "invalid expires time";
398				goto fail;
399			}
400			free(opt);
401			if (ret->valid_before == 0 ||
402			    valid_before < ret->valid_before)
403				ret->valid_before = valid_before;
404		} else if (opt_match(&opts, "environment")) {
405			if (ret->nenv > SSH_AUTHOPT_ENV_MAX) {
406				errstr = "too many environment strings";
407				goto fail;
408			}
409			if ((opt = opt_dequote(&opts, &errstr)) == NULL)
410				goto fail;
411			/* env name must be alphanumeric and followed by '=' */
412			if ((tmp = strchr(opt, '=')) == NULL) {
413				free(opt);
414				errstr = "invalid environment string";
415				goto fail;
416			}
417			if ((cp = strdup(opt)) == NULL) {
418				free(opt);
419				goto alloc_fail;
420			}
421			l = (size_t)(tmp - opt);
422			cp[l] = '\0'; /* truncate at '=' */
423			if (!valid_env_name(cp)) {
424				free(cp);
425				free(opt);
426				errstr = "invalid environment string";
427				goto fail;
428			}
429			/* Check for duplicates; XXX O(n*log(n)) */
430			for (i = 0; i < ret->nenv; i++) {
431				if (strncmp(ret->env[i], cp, l) == 0 &&
432				    ret->env[i][l] == '=')
433					break;
434			}
435			free(cp);
436			/* First match wins */
437			if (i >= ret->nenv) {
438				/* Append it. */
439				oarray = ret->env;
440				if ((ret->env = recallocarray(ret->env,
441				    ret->nenv, ret->nenv + 1,
442				    sizeof(*ret->env))) == NULL) {
443					free(opt);
444					/* put it back for cleanup */
445					ret->env = oarray;
446					goto alloc_fail;
447				}
448				ret->env[ret->nenv++] = opt;
449				opt = NULL; /* transferred */
450			}
451			free(opt);
452		} else if (opt_match(&opts, "permitopen")) {
453			if (handle_permit(&opts, 0, &ret->permitopen,
454			    &ret->npermitopen, &errstr) != 0)
455				goto fail;
456		} else if (opt_match(&opts, "permitlisten")) {
457			if (handle_permit(&opts, 1, &ret->permitlisten,
458			    &ret->npermitlisten, &errstr) != 0)
459				goto fail;
460		} else if (opt_match(&opts, "tunnel")) {
461			if ((opt = opt_dequote(&opts, &errstr)) == NULL)
462				goto fail;
463			ret->force_tun_device = a2tun(opt, NULL);
464			free(opt);
465			if (ret->force_tun_device == SSH_TUNID_ERR) {
466				errstr = "invalid tun device";
467				goto fail;
468			}
469		}
470		/*
471		 * Skip the comma, and move to the next option
472		 * (or break out if there are no more).
473		 */
474		if (*opts == '\0' || *opts == ' ' || *opts == '\t')
475			break;		/* End of options. */
476		/* Anything other than a comma is an unknown option */
477		if (*opts != ',') {
478			errstr = "unknown key option";
479			goto fail;
480		}
481		opts++;
482		if (*opts == '\0') {
483			errstr = "unexpected end-of-options";
484			goto fail;
485		}
486	}
487
488	/* success */
489	if (errstrp != NULL)
490		*errstrp = NULL;
491	return ret;
492
493alloc_fail:
494	errstr = "memory allocation failed";
495fail:
496	sshauthopt_free(ret);
497	if (errstrp != NULL)
498		*errstrp = errstr;
499	return NULL;
500}
501
502struct sshauthopt *
503sshauthopt_from_cert(struct sshkey *k)
504{
505	struct sshauthopt *ret;
506
507	if (k == NULL || !sshkey_type_is_cert(k->type) || k->cert == NULL ||
508	    k->cert->type != SSH2_CERT_TYPE_USER)
509		return NULL;
510
511	if ((ret = sshauthopt_new()) == NULL)
512		return NULL;
513
514	/* Handle options and critical extensions separately */
515	if (cert_option_list(ret, k->cert->critical,
516	    OPTIONS_CRITICAL, 1) == -1) {
517		sshauthopt_free(ret);
518		return NULL;
519	}
520	if (cert_option_list(ret, k->cert->extensions,
521	    OPTIONS_EXTENSIONS, 0) == -1) {
522		sshauthopt_free(ret);
523		return NULL;
524	}
525	/* success */
526	return ret;
527}
528
529/*
530 * Merges "additional" options to "primary" and returns the result.
531 * NB. Some options from primary have primacy.
532 */
533struct sshauthopt *
534sshauthopt_merge(const struct sshauthopt *primary,
535    const struct sshauthopt *additional, const char **errstrp)
536{
537	struct sshauthopt *ret;
538	const char *errstr = "internal error";
539	const char *tmp;
540
541	if (errstrp != NULL)
542		*errstrp = NULL;
543
544	if ((ret = sshauthopt_new()) == NULL)
545		goto alloc_fail;
546
547	/* cert_authority and cert_principals are cleared in result */
548
549	/* Prefer access lists from primary. */
550	/* XXX err is both set and mismatch? */
551	tmp = primary->required_from_host_cert;
552	if (tmp == NULL)
553		tmp = additional->required_from_host_cert;
554	if (tmp != NULL && (ret->required_from_host_cert = strdup(tmp)) == NULL)
555		goto alloc_fail;
556	tmp = primary->required_from_host_keys;
557	if (tmp == NULL)
558		tmp = additional->required_from_host_keys;
559	if (tmp != NULL && (ret->required_from_host_keys = strdup(tmp)) == NULL)
560		goto alloc_fail;
561
562	/*
563	 * force_tun_device, permitopen/permitlisten and environment all
564	 * prefer the primary.
565	 */
566	ret->force_tun_device = primary->force_tun_device;
567	if (ret->force_tun_device == -1)
568		ret->force_tun_device = additional->force_tun_device;
569	if (primary->nenv > 0) {
570		if (dup_strings(&ret->env, &ret->nenv,
571		    primary->env, primary->nenv) != 0)
572			goto alloc_fail;
573	} else if (additional->nenv) {
574		if (dup_strings(&ret->env, &ret->nenv,
575		    additional->env, additional->nenv) != 0)
576			goto alloc_fail;
577	}
578	if (primary->npermitopen > 0) {
579		if (dup_strings(&ret->permitopen, &ret->npermitopen,
580		    primary->permitopen, primary->npermitopen) != 0)
581			goto alloc_fail;
582	} else if (additional->npermitopen > 0) {
583		if (dup_strings(&ret->permitopen, &ret->npermitopen,
584		    additional->permitopen, additional->npermitopen) != 0)
585			goto alloc_fail;
586	}
587
588	if (primary->npermitlisten > 0) {
589		if (dup_strings(&ret->permitlisten, &ret->npermitlisten,
590		    primary->permitlisten, primary->npermitlisten) != 0)
591			goto alloc_fail;
592	} else if (additional->npermitlisten > 0) {
593		if (dup_strings(&ret->permitlisten, &ret->npermitlisten,
594		    additional->permitlisten, additional->npermitlisten) != 0)
595			goto alloc_fail;
596	}
597
598#define OPTFLAG_AND(x) ret->x = (primary->x == 1) && (additional->x == 1)
599#define OPTFLAG_OR(x) ret->x = (primary->x == 1) || (additional->x == 1)
600	/* Permissive flags are logical-AND (i.e. must be set in both) */
601	OPTFLAG_AND(permit_port_forwarding_flag);
602	OPTFLAG_AND(permit_agent_forwarding_flag);
603	OPTFLAG_AND(permit_x11_forwarding_flag);
604	OPTFLAG_AND(permit_pty_flag);
605	OPTFLAG_AND(permit_user_rc);
606	OPTFLAG_AND(no_require_user_presence);
607	/* Restrictive flags are logical-OR (i.e. must be set in either) */
608	OPTFLAG_OR(require_verify);
609#undef OPTFLAG_AND
610
611	/* Earliest expiry time should win */
612	if (primary->valid_before != 0)
613		ret->valid_before = primary->valid_before;
614	if (additional->valid_before != 0 &&
615	    additional->valid_before < ret->valid_before)
616		ret->valid_before = additional->valid_before;
617
618	/*
619	 * When both multiple forced-command are specified, only
620	 * proceed if they are identical, otherwise fail.
621	 */
622	if (primary->force_command != NULL &&
623	    additional->force_command != NULL) {
624		if (strcmp(primary->force_command,
625		    additional->force_command) == 0) {
626			/* ok */
627			ret->force_command = strdup(primary->force_command);
628			if (ret->force_command == NULL)
629				goto alloc_fail;
630		} else {
631			errstr = "forced command options do not match";
632			goto fail;
633		}
634	} else if (primary->force_command != NULL) {
635		if ((ret->force_command = strdup(
636		    primary->force_command)) == NULL)
637			goto alloc_fail;
638	} else if (additional->force_command != NULL) {
639		if ((ret->force_command = strdup(
640		    additional->force_command)) == NULL)
641			goto alloc_fail;
642	}
643	/* success */
644	if (errstrp != NULL)
645		*errstrp = NULL;
646	return ret;
647
648 alloc_fail:
649	errstr = "memory allocation failed";
650 fail:
651	if (errstrp != NULL)
652		*errstrp = errstr;
653	sshauthopt_free(ret);
654	return NULL;
655}
656
657/*
658 * Copy options
659 */
660struct sshauthopt *
661sshauthopt_copy(const struct sshauthopt *orig)
662{
663	struct sshauthopt *ret;
664
665	if ((ret = sshauthopt_new()) == NULL)
666		return NULL;
667
668#define OPTSCALAR(x) ret->x = orig->x
669	OPTSCALAR(permit_port_forwarding_flag);
670	OPTSCALAR(permit_agent_forwarding_flag);
671	OPTSCALAR(permit_x11_forwarding_flag);
672	OPTSCALAR(permit_pty_flag);
673	OPTSCALAR(permit_user_rc);
674	OPTSCALAR(restricted);
675	OPTSCALAR(cert_authority);
676	OPTSCALAR(force_tun_device);
677	OPTSCALAR(valid_before);
678	OPTSCALAR(no_require_user_presence);
679	OPTSCALAR(require_verify);
680#undef OPTSCALAR
681#define OPTSTRING(x) \
682	do { \
683		if (orig->x != NULL && (ret->x = strdup(orig->x)) == NULL) { \
684			sshauthopt_free(ret); \
685			return NULL; \
686		} \
687	} while (0)
688	OPTSTRING(cert_principals);
689	OPTSTRING(force_command);
690	OPTSTRING(required_from_host_cert);
691	OPTSTRING(required_from_host_keys);
692#undef OPTSTRING
693
694	if (dup_strings(&ret->env, &ret->nenv, orig->env, orig->nenv) != 0 ||
695	    dup_strings(&ret->permitopen, &ret->npermitopen,
696	    orig->permitopen, orig->npermitopen) != 0 ||
697	    dup_strings(&ret->permitlisten, &ret->npermitlisten,
698	    orig->permitlisten, orig->npermitlisten) != 0) {
699		sshauthopt_free(ret);
700		return NULL;
701	}
702	return ret;
703}
704
705static int
706serialise_array(struct sshbuf *m, char **a, size_t n)
707{
708	struct sshbuf *b;
709	size_t i;
710	int r = SSH_ERR_INTERNAL_ERROR;
711
712	if (n > INT_MAX)
713		return SSH_ERR_INTERNAL_ERROR;
714
715	if ((b = sshbuf_new()) == NULL) {
716		return SSH_ERR_ALLOC_FAIL;
717	}
718	for (i = 0; i < n; i++) {
719		if ((r = sshbuf_put_cstring(b, a[i])) != 0)
720			goto out;
721	}
722	if ((r = sshbuf_put_u32(m, n)) != 0 ||
723	    (r = sshbuf_put_stringb(m, b)) != 0)
724		goto out;
725	/* success */
726	r = 0;
727 out:
728	sshbuf_free(b);
729	return r;
730}
731
732static int
733deserialise_array(struct sshbuf *m, char ***ap, size_t *np)
734{
735	char **a = NULL;
736	size_t i, n = 0;
737	struct sshbuf *b = NULL;
738	u_int tmp;
739	int r = SSH_ERR_INTERNAL_ERROR;
740
741	if ((r = sshbuf_get_u32(m, &tmp)) != 0 ||
742	    (r = sshbuf_froms(m, &b)) != 0)
743		goto out;
744	if (tmp > INT_MAX) {
745		r = SSH_ERR_INVALID_FORMAT;
746		goto out;
747	}
748	n = tmp;
749	if (n > 0 && (a = calloc(n, sizeof(*a))) == NULL) {
750		r = SSH_ERR_ALLOC_FAIL;
751		goto out;
752	}
753	for (i = 0; i < n; i++) {
754		if ((r = sshbuf_get_cstring(b, &a[i], NULL)) != 0)
755			goto out;
756	}
757	/* success */
758	r = 0;
759	*ap = a;
760	a = NULL;
761	*np = n;
762	n = 0;
763 out:
764	if (a != NULL) {
765		for (i = 0; i < n; i++)
766			free(a[i]);
767		free(a);
768	}
769	sshbuf_free(b);
770	return r;
771}
772
773static int
774serialise_nullable_string(struct sshbuf *m, const char *s)
775{
776	int r;
777
778	if ((r = sshbuf_put_u8(m, s == NULL)) != 0 ||
779	    (r = sshbuf_put_cstring(m, s)) != 0)
780		return r;
781	return 0;
782}
783
784static int
785deserialise_nullable_string(struct sshbuf *m, char **sp)
786{
787	int r;
788	u_char flag;
789
790	*sp = NULL;
791	if ((r = sshbuf_get_u8(m, &flag)) != 0 ||
792	    (r = sshbuf_get_cstring(m, flag ? NULL : sp, NULL)) != 0)
793		return r;
794	return 0;
795}
796
797int
798sshauthopt_serialise(const struct sshauthopt *opts, struct sshbuf *m,
799    int untrusted)
800{
801	int r = SSH_ERR_INTERNAL_ERROR;
802
803	/* Flag options */
804	if ((r = sshbuf_put_u8(m, opts->permit_port_forwarding_flag)) != 0 ||
805	    (r = sshbuf_put_u8(m, opts->permit_agent_forwarding_flag)) != 0 ||
806	    (r = sshbuf_put_u8(m, opts->permit_x11_forwarding_flag)) != 0 ||
807	    (r = sshbuf_put_u8(m, opts->permit_pty_flag)) != 0 ||
808	    (r = sshbuf_put_u8(m, opts->permit_user_rc)) != 0 ||
809	    (r = sshbuf_put_u8(m, opts->restricted)) != 0 ||
810	    (r = sshbuf_put_u8(m, opts->cert_authority)) != 0 ||
811	    (r = sshbuf_put_u8(m, opts->no_require_user_presence)) != 0 ||
812	    (r = sshbuf_put_u8(m, opts->require_verify)) != 0)
813		return r;
814
815	/* Simple integer options */
816	if ((r = sshbuf_put_u64(m, opts->valid_before)) != 0)
817		return r;
818
819	/* tunnel number can be negative to indicate "unset" */
820	if ((r = sshbuf_put_u8(m, opts->force_tun_device == -1)) != 0 ||
821	    (r = sshbuf_put_u32(m, (opts->force_tun_device < 0) ?
822	    0 : (u_int)opts->force_tun_device)) != 0)
823		return r;
824
825	/* String options; these may be NULL */
826	if ((r = serialise_nullable_string(m,
827	    untrusted ? "yes" : opts->cert_principals)) != 0 ||
828	    (r = serialise_nullable_string(m,
829	    untrusted ? "true" : opts->force_command)) != 0 ||
830	    (r = serialise_nullable_string(m,
831	    untrusted ? NULL : opts->required_from_host_cert)) != 0 ||
832	    (r = serialise_nullable_string(m,
833	    untrusted ? NULL : opts->required_from_host_keys)) != 0)
834		return r;
835
836	/* Array options */
837	if ((r = serialise_array(m, opts->env,
838	    untrusted ? 0 : opts->nenv)) != 0 ||
839	    (r = serialise_array(m, opts->permitopen,
840	    untrusted ? 0 : opts->npermitopen)) != 0 ||
841	    (r = serialise_array(m, opts->permitlisten,
842	    untrusted ? 0 : opts->npermitlisten)) != 0)
843		return r;
844
845	/* success */
846	return 0;
847}
848
849int
850sshauthopt_deserialise(struct sshbuf *m, struct sshauthopt **optsp)
851{
852	struct sshauthopt *opts = NULL;
853	int r = SSH_ERR_INTERNAL_ERROR;
854	u_char f;
855	u_int tmp;
856
857	if ((opts = calloc(1, sizeof(*opts))) == NULL)
858		return SSH_ERR_ALLOC_FAIL;
859
860	/* Flag options */
861#define OPT_FLAG(x) \
862	do { \
863		if ((r = sshbuf_get_u8(m, &f)) != 0) \
864			goto out; \
865		opts->x = f; \
866	} while (0)
867	OPT_FLAG(permit_port_forwarding_flag);
868	OPT_FLAG(permit_agent_forwarding_flag);
869	OPT_FLAG(permit_x11_forwarding_flag);
870	OPT_FLAG(permit_pty_flag);
871	OPT_FLAG(permit_user_rc);
872	OPT_FLAG(restricted);
873	OPT_FLAG(cert_authority);
874	OPT_FLAG(no_require_user_presence);
875	OPT_FLAG(require_verify);
876#undef OPT_FLAG
877
878	/* Simple integer options */
879	if ((r = sshbuf_get_u64(m, &opts->valid_before)) != 0)
880		goto out;
881
882	/* tunnel number can be negative to indicate "unset" */
883	if ((r = sshbuf_get_u8(m, &f)) != 0 ||
884	    (r = sshbuf_get_u32(m, &tmp)) != 0)
885		goto out;
886	opts->force_tun_device = f ? -1 : (int)tmp;
887
888	/* String options may be NULL */
889	if ((r = deserialise_nullable_string(m, &opts->cert_principals)) != 0 ||
890	    (r = deserialise_nullable_string(m, &opts->force_command)) != 0 ||
891	    (r = deserialise_nullable_string(m,
892	    &opts->required_from_host_cert)) != 0 ||
893	    (r = deserialise_nullable_string(m,
894	    &opts->required_from_host_keys)) != 0)
895		goto out;
896
897	/* Array options */
898	if ((r = deserialise_array(m, &opts->env, &opts->nenv)) != 0 ||
899	    (r = deserialise_array(m,
900	    &opts->permitopen, &opts->npermitopen)) != 0 ||
901	    (r = deserialise_array(m,
902	    &opts->permitlisten, &opts->npermitlisten)) != 0)
903		goto out;
904
905	/* success */
906	r = 0;
907	*optsp = opts;
908	opts = NULL;
909 out:
910	sshauthopt_free(opts);
911	return r;
912}
913