1 /* $OpenBSD: auth-options.c,v 1.70 2015/12/10 17:08:40 mmcc Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * As far as I am concerned, the code I have written for this software
7 * can be used freely for any purpose. Any derived versions of this
8 * software must be clearly marked as such, and if the derived work is
9 * incompatible with the protocol description in the RFC file, it must be
10 * called by a name other than "ssh" or "Secure Shell".
15 #include <sys/types.h>
23 #include "openbsd-compat/sys-queue.h"
25 #include "key.h" /* XXX for typedef */
26 #include "buffer.h" /* XXX for typedef */
37 #include "auth-options.h"
41 /* Flags set authorized_keys flags */
42 int no_port_forwarding_flag = 0;
43 int no_agent_forwarding_flag = 0;
44 int no_x11_forwarding_flag = 0;
47 int key_is_cert_authority = 0;
49 /* "command=" option. */
50 char *forced_command = NULL;
52 /* "environment=" options. */
53 struct envstring *custom_environment = NULL;
55 /* "tunnel=" option. */
56 int forced_tun_device = -1;
58 /* "principals=" option. */
59 char *authorized_principals = NULL;
61 extern ServerOptions options;
64 auth_clear_options(void)
66 no_agent_forwarding_flag = 0;
67 no_port_forwarding_flag = 0;
69 no_x11_forwarding_flag = 0;
71 key_is_cert_authority = 0;
72 while (custom_environment) {
73 struct envstring *ce = custom_environment;
74 custom_environment = ce->next;
79 forced_command = NULL;
80 free(authorized_principals);
81 authorized_principals = NULL;
82 forced_tun_device = -1;
83 channel_clear_permitted_opens();
87 * Match flag 'opt' in *optsp, and if allow_negate is set then also match
88 * 'no-opt'. Returns -1 if option not matched, 1 if option matches or 0
89 * if negated option matches.
90 * If the option or negated option matches, then *optsp is updated to
91 * point to the first character after the option and, if 'msg' is not NULL
92 * then a message based on it added via auth_debug_add().
95 match_flag(const char *opt, int allow_negate, char **optsp, const char *msg)
97 size_t opt_len = strlen(opt);
101 if (allow_negate && strncasecmp(opts, "no-", 3) == 0) {
105 if (strncasecmp(opts, opt, opt_len) == 0) {
106 *optsp = opts + opt_len;
108 auth_debug_add("%s %s.", msg,
109 negate ? "disabled" : "enabled");
111 return negate ? 0 : 1;
117 * return 1 if access is granted, 0 if not.
118 * side effect: sets key option flags
121 auth_parse_options(struct passwd *pw, char *opts, char *file, u_long linenum)
127 auth_clear_options();
132 while (*opts && *opts != ' ' && *opts != '\t') {
133 if ((r = match_flag("cert-authority", 0, &opts, NULL)) != -1) {
134 key_is_cert_authority = r;
137 if ((r = match_flag("restrict", 0, &opts, NULL)) != -1) {
138 auth_debug_add("Key is restricted.");
139 no_port_forwarding_flag = 1;
140 no_agent_forwarding_flag = 1;
141 no_x11_forwarding_flag = 1;
146 if ((r = match_flag("port-forwarding", 1, &opts,
147 "Port forwarding")) != -1) {
148 no_port_forwarding_flag = r != 1;
151 if ((r = match_flag("agent-forwarding", 1, &opts,
152 "Agent forwarding")) != -1) {
153 no_agent_forwarding_flag = r != 1;
156 if ((r = match_flag("x11-forwarding", 1, &opts,
157 "X11 forwarding")) != -1) {
158 no_x11_forwarding_flag = r != 1;
161 if ((r = match_flag("pty", 1, &opts,
162 "PTY allocation")) != -1) {
163 no_pty_flag = r != 1;
166 if ((r = match_flag("user-rc", 1, &opts,
167 "User rc execution")) != -1) {
172 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
174 free(forced_command);
175 forced_command = xmalloc(strlen(opts) + 1);
180 if (*opts == '\\' && opts[1] == '"') {
182 forced_command[i++] = '"';
185 forced_command[i++] = *opts++;
188 debug("%.100s, line %lu: missing end quote",
190 auth_debug_add("%.100s, line %lu: missing end quote",
192 free(forced_command);
193 forced_command = NULL;
196 forced_command[i] = '\0';
197 auth_debug_add("Forced command.");
201 cp = "principals=\"";
202 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
204 free(authorized_principals);
205 authorized_principals = xmalloc(strlen(opts) + 1);
210 if (*opts == '\\' && opts[1] == '"') {
212 authorized_principals[i++] = '"';
215 authorized_principals[i++] = *opts++;
218 debug("%.100s, line %lu: missing end quote",
220 auth_debug_add("%.100s, line %lu: missing end quote",
222 free(authorized_principals);
223 authorized_principals = NULL;
226 authorized_principals[i] = '\0';
227 auth_debug_add("principals: %.900s",
228 authorized_principals);
232 cp = "environment=\"";
233 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
235 struct envstring *new_envstring;
238 s = xmalloc(strlen(opts) + 1);
243 if (*opts == '\\' && opts[1] == '"') {
251 debug("%.100s, line %lu: missing end quote",
253 auth_debug_add("%.100s, line %lu: missing end quote",
260 if (options.permit_user_env) {
261 auth_debug_add("Adding to environment: "
263 debug("Adding to environment: %.900s", s);
264 new_envstring = xcalloc(1,
265 sizeof(*new_envstring));
266 new_envstring->s = s;
267 new_envstring->next = custom_environment;
268 custom_environment = new_envstring;
275 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
276 const char *remote_ip = get_remote_ipaddr();
277 const char *remote_host = get_canonical_hostname(
279 char *patterns = xmalloc(strlen(opts) + 1);
286 if (*opts == '\\' && opts[1] == '"') {
291 patterns[i++] = *opts++;
294 debug("%.100s, line %lu: missing end quote",
296 auth_debug_add("%.100s, line %lu: missing end quote",
303 switch (match_host_and_ip(remote_host, remote_ip,
307 /* Host name matches. */
310 debug("%.100s, line %lu: invalid criteria",
312 auth_debug_add("%.100s, line %lu: "
313 "invalid criteria", file, linenum);
317 logit("Authentication tried for %.100s with "
318 "correct key but not from a permitted "
319 "host (host=%.200s, ip=%.200s).",
320 pw->pw_name, remote_host, remote_ip);
321 auth_debug_add("Your host '%.200s' is not "
322 "permitted to use this key for login.",
329 cp = "permitopen=\"";
330 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
333 char *patterns = xmalloc(strlen(opts) + 1);
340 if (*opts == '\\' && opts[1] == '"') {
345 patterns[i++] = *opts++;
348 debug("%.100s, line %lu: missing end quote",
350 auth_debug_add("%.100s, line %lu: missing "
351 "end quote", file, linenum);
358 /* XXX - add streamlocal support */
360 if (host == NULL || strlen(host) >= NI_MAXHOST) {
361 debug("%.100s, line %lu: Bad permitopen "
362 "specification <%.100s>", file, linenum,
364 auth_debug_add("%.100s, line %lu: "
365 "Bad permitopen specification", file,
370 host = cleanhostname(host);
371 if (p == NULL || (port = permitopen_port(p)) < 0) {
372 debug("%.100s, line %lu: Bad permitopen port "
373 "<%.100s>", file, linenum, p ? p : "");
374 auth_debug_add("%.100s, line %lu: "
375 "Bad permitopen port", file, linenum);
379 if ((options.allow_tcp_forwarding & FORWARD_LOCAL) != 0)
380 channel_add_permitted_opens(host, port);
385 if (strncasecmp(opts, cp, strlen(cp)) == 0) {
388 tun = xmalloc(strlen(opts) + 1);
396 debug("%.100s, line %lu: missing end quote",
398 auth_debug_add("%.100s, line %lu: missing end quote",
401 forced_tun_device = -1;
405 forced_tun_device = a2tun(tun, NULL);
407 if (forced_tun_device == SSH_TUNID_ERR) {
408 debug("%.100s, line %lu: invalid tun device",
410 auth_debug_add("%.100s, line %lu: invalid tun device",
412 forced_tun_device = -1;
415 auth_debug_add("Forced tun device: %d", forced_tun_device);
421 * Skip the comma, and move to the next option
422 * (or break out if there are no more).
425 fatal("Bugs in auth-options.c option processing.");
426 if (*opts == ' ' || *opts == '\t')
427 break; /* End of options. */
431 /* Process the next option. */
438 logit("Bad options in %.100s file, line %lu: %.50s",
439 file, linenum, opts);
440 auth_debug_add("Bad options in %.100s file, line %lu: %.50s",
441 file, linenum, opts);
447 #define OPTIONS_CRITICAL 1
448 #define OPTIONS_EXTENSIONS 2
450 parse_option_list(struct sshbuf *oblob, struct passwd *pw,
451 u_int which, int crit,
452 int *cert_no_port_forwarding_flag,
453 int *cert_no_agent_forwarding_flag,
454 int *cert_no_x11_forwarding_flag,
455 int *cert_no_pty_flag,
456 int *cert_no_user_rc,
457 char **cert_forced_command,
458 int *cert_source_address_done)
460 char *command, *allowed;
461 const char *remote_ip;
463 struct sshbuf *c = NULL, *data = NULL;
464 int r, ret = -1, result, found;
466 if ((c = sshbuf_fromb(oblob)) == NULL) {
467 error("%s: sshbuf_fromb failed", __func__);
471 while (sshbuf_len(c) > 0) {
474 if ((r = sshbuf_get_cstring(c, &name, NULL)) != 0 ||
475 (r = sshbuf_froms(c, &data)) != 0) {
476 error("Unable to parse certificate options: %s",
480 debug3("found certificate option \"%.100s\" len %zu",
481 name, sshbuf_len(data));
483 if ((which & OPTIONS_EXTENSIONS) != 0) {
484 if (strcmp(name, "permit-X11-forwarding") == 0) {
485 *cert_no_x11_forwarding_flag = 0;
487 } else if (strcmp(name,
488 "permit-agent-forwarding") == 0) {
489 *cert_no_agent_forwarding_flag = 0;
491 } else if (strcmp(name,
492 "permit-port-forwarding") == 0) {
493 *cert_no_port_forwarding_flag = 0;
495 } else if (strcmp(name, "permit-pty") == 0) {
496 *cert_no_pty_flag = 0;
498 } else if (strcmp(name, "permit-user-rc") == 0) {
499 *cert_no_user_rc = 0;
503 if (!found && (which & OPTIONS_CRITICAL) != 0) {
504 if (strcmp(name, "force-command") == 0) {
505 if ((r = sshbuf_get_cstring(data, &command,
507 error("Unable to parse \"%s\" "
508 "section: %s", name, ssh_err(r));
511 if (*cert_forced_command != NULL) {
512 error("Certificate has multiple "
513 "force-command options");
517 *cert_forced_command = command;
520 if (strcmp(name, "source-address") == 0) {
521 if ((r = sshbuf_get_cstring(data, &allowed,
523 error("Unable to parse \"%s\" "
524 "section: %s", name, ssh_err(r));
527 if ((*cert_source_address_done)++) {
528 error("Certificate has multiple "
529 "source-address options");
533 remote_ip = get_remote_ipaddr();
534 result = addr_match_cidr_list(remote_ip,
543 logit("Authentication tried for %.100s "
544 "with valid certificate but not "
545 "from a permitted host "
546 "(ip=%.200s).", pw->pw_name,
548 auth_debug_add("Your address '%.200s' "
549 "is not permitted to use this "
550 "certificate for login.",
555 error("Certificate source-address "
565 error("Certificate critical option \"%s\" "
566 "is not supported", name);
569 logit("Certificate extension \"%s\" "
570 "is not supported", name);
572 } else if (sshbuf_len(data) != 0) {
573 error("Certificate option \"%s\" corrupt "
574 "(extra data)", name);
580 /* successfully parsed all options */
585 cert_forced_command != NULL &&
586 *cert_forced_command != NULL) {
587 free(*cert_forced_command);
588 *cert_forced_command = NULL;
597 * Set options from critical certificate options. These supersede user key
598 * options so this must be called after auth_parse_options().
601 auth_cert_options(struct sshkey *k, struct passwd *pw)
603 int cert_no_port_forwarding_flag = 1;
604 int cert_no_agent_forwarding_flag = 1;
605 int cert_no_x11_forwarding_flag = 1;
606 int cert_no_pty_flag = 1;
607 int cert_no_user_rc = 1;
608 char *cert_forced_command = NULL;
609 int cert_source_address_done = 0;
611 /* Separate options and extensions for v01 certs */
612 if (parse_option_list(k->cert->critical, pw,
613 OPTIONS_CRITICAL, 1, NULL, NULL, NULL, NULL, NULL,
614 &cert_forced_command,
615 &cert_source_address_done) == -1)
617 if (parse_option_list(k->cert->extensions, pw,
618 OPTIONS_EXTENSIONS, 0,
619 &cert_no_port_forwarding_flag,
620 &cert_no_agent_forwarding_flag,
621 &cert_no_x11_forwarding_flag,
627 no_port_forwarding_flag |= cert_no_port_forwarding_flag;
628 no_agent_forwarding_flag |= cert_no_agent_forwarding_flag;
629 no_x11_forwarding_flag |= cert_no_x11_forwarding_flag;
630 no_pty_flag |= cert_no_pty_flag;
631 no_user_rc |= cert_no_user_rc;
632 /* CA-specified forced command supersedes key option */
633 if (cert_forced_command != NULL) {
634 free(forced_command);
635 forced_command = cert_forced_command;