1 /* $OpenBSD: auth2-pubkey.c,v 1.87 2019/01/22 11:26:16 djm Exp $ */
3 * Copyright (c) 2000 Markus Friedl. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 #include <sys/types.h>
57 #include "pathnames.h"
59 #include "auth-options.h"
64 #include "monitor_wrap.h"
68 #include "channels.h" /* XXX for session.h */
69 #include "session.h" /* XXX for child_set_env(); refactor? */
72 extern ServerOptions options;
73 extern u_char *session_id2;
74 extern u_int session_id2_len;
77 format_key(const struct sshkey *key)
79 char *ret, *fp = sshkey_fingerprint(key,
80 options.fingerprint_hash, SSH_FP_DEFAULT);
82 xasprintf(&ret, "%s %s", sshkey_type(key), fp);
88 userauth_pubkey(struct ssh *ssh)
90 Authctxt *authctxt = ssh->authctxt;
91 struct passwd *pw = authctxt->pw;
92 struct sshbuf *b = NULL;
93 struct sshkey *key = NULL;
94 char *pkalg = NULL, *userstyle = NULL, *key_s = NULL, *ca_s = NULL;
95 u_char *pkblob = NULL, *sig = NULL, have_sig;
98 int authenticated = 0;
99 struct sshauthopt *authopts = NULL;
101 if ((r = sshpkt_get_u8(ssh, &have_sig)) != 0 ||
102 (r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 ||
103 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0)
104 fatal("%s: parse request failed: %s", __func__, ssh_err(r));
106 if (log_level_get() >= SYSLOG_LEVEL_DEBUG2) {
108 struct sshbuf *pkbuf;
110 if ((pkbuf = sshbuf_from(pkblob, blen)) == NULL)
111 fatal("%s: sshbuf_from failed", __func__);
112 if ((keystring = sshbuf_dtob64(pkbuf)) == NULL)
113 fatal("%s: sshbuf_dtob64 failed", __func__);
114 debug2("%s: %s user %s %s public key %s %s", __func__,
115 authctxt->valid ? "valid" : "invalid", authctxt->user,
116 have_sig ? "attempting" : "querying", pkalg, keystring);
121 pktype = sshkey_type_from_name(pkalg);
122 if (pktype == KEY_UNSPEC) {
123 /* this is perfectly legal */
124 verbose("%s: unsupported public key algorithm: %s",
128 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
129 error("%s: could not parse key: %s", __func__, ssh_err(r));
133 error("%s: cannot decode key: %s", __func__, pkalg);
136 if (key->type != pktype) {
137 error("%s: type mismatch for decoded key "
138 "(received %d, expected %d)", __func__, key->type, pktype);
141 if (sshkey_type_plain(key->type) == KEY_RSA &&
142 (ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
143 logit("Refusing RSA key because client uses unsafe "
147 if (auth2_key_already_used(authctxt, key)) {
148 logit("refusing previously-used %s key", sshkey_type(key));
151 if (match_pattern_list(pkalg, options.pubkey_key_types, 0) != 1) {
152 logit("%s: key type %s not in PubkeyAcceptedKeyTypes",
153 __func__, sshkey_ssh_name(key));
156 if ((r = sshkey_check_cert_sigtype(key,
157 options.ca_sign_algorithms)) != 0) {
158 logit("%s: certificate signature algorithm %s: %s", __func__,
159 (key->cert == NULL || key->cert->signature_type == NULL) ?
160 "(null)" : key->cert->signature_type, ssh_err(r));
163 key_s = format_key(key);
164 if (sshkey_is_cert(key))
165 ca_s = format_key(key->cert->signature_key);
168 debug3("%s: have %s signature for %s%s%s",
169 __func__, pkalg, key_s,
170 ca_s == NULL ? "" : " CA ",
171 ca_s == NULL ? "" : ca_s);
172 if ((r = sshpkt_get_string(ssh, &sig, &slen)) != 0 ||
173 (r = sshpkt_get_end(ssh)) != 0)
174 fatal("%s: %s", __func__, ssh_err(r));
175 if ((b = sshbuf_new()) == NULL)
176 fatal("%s: sshbuf_new failed", __func__);
177 if (ssh->compat & SSH_OLD_SESSIONID) {
178 if ((r = sshbuf_put(b, session_id2,
179 session_id2_len)) != 0)
180 fatal("%s: sshbuf_put session id: %s",
181 __func__, ssh_err(r));
183 if ((r = sshbuf_put_string(b, session_id2,
184 session_id2_len)) != 0)
185 fatal("%s: sshbuf_put_string session id: %s",
186 __func__, ssh_err(r));
188 if (!authctxt->valid || authctxt->user == NULL) {
189 debug2("%s: disabled because of invalid user",
193 /* reconstruct packet */
194 xasprintf(&userstyle, "%s%s%s", authctxt->user,
195 authctxt->style ? ":" : "",
196 authctxt->style ? authctxt->style : "");
197 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
198 (r = sshbuf_put_cstring(b, userstyle)) != 0 ||
199 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
200 (r = sshbuf_put_cstring(b, "publickey")) != 0 ||
201 (r = sshbuf_put_u8(b, have_sig)) != 0 ||
202 (r = sshbuf_put_cstring(b, pkalg)) != 0 ||
203 (r = sshbuf_put_string(b, pkblob, blen)) != 0)
204 fatal("%s: build packet failed: %s",
205 __func__, ssh_err(r));
207 sshbuf_dump(b, stderr);
209 /* test for correct signature */
211 if (PRIVSEP(user_key_allowed(ssh, pw, key, 1, &authopts)) &&
212 PRIVSEP(sshkey_verify(key, sig, slen,
213 sshbuf_ptr(b), sshbuf_len(b),
214 (ssh->compat & SSH_BUG_SIGTYPE) == 0 ? pkalg : NULL,
215 ssh->compat)) == 0) {
218 auth2_record_key(authctxt, authenticated, key);
220 debug("%s: test pkalg %s pkblob %s%s%s",
221 __func__, pkalg, key_s,
222 ca_s == NULL ? "" : " CA ",
223 ca_s == NULL ? "" : ca_s);
225 if ((r = sshpkt_get_end(ssh)) != 0)
226 fatal("%s: %s", __func__, ssh_err(r));
228 if (!authctxt->valid || authctxt->user == NULL) {
229 debug2("%s: disabled because of invalid user",
233 /* XXX fake reply and always send PK_OK ? */
235 * XXX this allows testing whether a user is allowed
236 * to login: if you happen to have a valid pubkey this
237 * message is sent. the message is NEVER sent at all
238 * if a user is not allowed to login. is this an
241 if (PRIVSEP(user_key_allowed(ssh, pw, key, 0, NULL))) {
242 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_PK_OK))
244 (r = sshpkt_put_cstring(ssh, pkalg)) != 0 ||
245 (r = sshpkt_put_string(ssh, pkblob, blen)) != 0 ||
246 (r = sshpkt_send(ssh)) != 0 ||
247 (r = ssh_packet_write_wait(ssh)) != 0)
248 fatal("%s: %s", __func__, ssh_err(r));
249 authctxt->postponed = 1;
253 if (authenticated == 1 && auth_activate_options(ssh, authopts) != 0) {
254 debug("%s: key options inconsistent with existing", __func__);
257 debug2("%s: authenticated %d pkalg %s", __func__, authenticated, pkalg);
260 sshauthopt_free(authopts);
268 return authenticated;
272 match_principals_option(const char *principal_list, struct sshkey_cert *cert)
277 /* XXX percent_expand() sequences for authorized_principals? */
279 for (i = 0; i < cert->nprincipals; i++) {
280 if ((result = match_list(cert->principals[i],
281 principal_list, NULL)) != NULL) {
282 debug3("matched principal from key options \"%.100s\"",
292 * Process a single authorized_principals format line. Returns 0 and sets
293 * authoptsp is principal is authorised, -1 otherwise. "loc" is used as a
294 * log preamble for file/line information.
297 check_principals_line(struct ssh *ssh, char *cp, const struct sshkey_cert *cert,
298 const char *loc, struct sshauthopt **authoptsp)
301 char *ep, *line_opts;
302 const char *reason = NULL;
303 struct sshauthopt *opts = NULL;
305 if (authoptsp != NULL)
308 /* Trim trailing whitespace. */
309 ep = cp + strlen(cp) - 1;
310 while (ep > cp && (*ep == '\n' || *ep == ' ' || *ep == '\t'))
314 * If the line has internal whitespace then assume it has
318 if ((ep = strrchr(cp, ' ')) != NULL ||
319 (ep = strrchr(cp, '\t')) != NULL) {
320 for (; *ep == ' ' || *ep == '\t'; ep++)
325 if ((opts = sshauthopt_parse(line_opts, &reason)) == NULL) {
326 debug("%s: bad principals options: %s", loc, reason);
327 auth_debug_add("%s: bad principals options: %s", loc, reason);
330 /* Check principals in cert against those on line */
331 for (i = 0; i < cert->nprincipals; i++) {
332 if (strcmp(cp, cert->principals[i]) != 0)
334 debug3("%s: matched principal \"%.100s\"",
335 loc, cert->principals[i]);
338 if (found && authoptsp != NULL) {
342 sshauthopt_free(opts);
343 return found ? 0 : -1;
347 process_principals(struct ssh *ssh, FILE *f, const char *file,
348 const struct sshkey_cert *cert, struct sshauthopt **authoptsp)
350 char loc[256], *line = NULL, *cp, *ep;
353 u_int found_principal = 0;
355 if (authoptsp != NULL)
358 while (getline(&line, &linesize, f) != -1) {
360 /* Always consume entire input */
364 /* Skip leading whitespace. */
365 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
367 /* Skip blank and comment lines. */
368 if ((ep = strchr(cp, '#')) != NULL)
370 if (!*cp || *cp == '\n')
373 snprintf(loc, sizeof(loc), "%.200s:%lu", file, linenum);
374 if (check_principals_line(ssh, cp, cert, loc, authoptsp) == 0)
378 return found_principal;
381 /* XXX remove pw args here and elsewhere once ssh->authctxt is guaranteed */
384 match_principals_file(struct ssh *ssh, struct passwd *pw, char *file,
385 struct sshkey_cert *cert, struct sshauthopt **authoptsp)
390 if (authoptsp != NULL)
393 temporarily_use_uid(pw);
394 debug("trying authorized principals file %s", file);
395 if ((f = auth_openprincipals(file, pw, options.strict_modes)) == NULL) {
399 success = process_principals(ssh, f, file, cert, authoptsp);
406 * Checks whether principal is allowed in output of command.
407 * returns 1 if the principal is allowed or 0 otherwise.
410 match_principals_command(struct ssh *ssh, struct passwd *user_pw,
411 const struct sshkey *key, struct sshauthopt **authoptsp)
413 struct passwd *runas_pw = NULL;
414 const struct sshkey_cert *cert = key->cert;
416 int r, ok, found_principal = 0;
417 int i, ac = 0, uid_swapped = 0;
419 char *tmp, *username = NULL, *command = NULL, **av = NULL;
420 char *ca_fp = NULL, *key_fp = NULL, *catext = NULL, *keytext = NULL;
421 char serial_s[16], uidstr[32];
422 void (*osigchld)(int);
424 if (authoptsp != NULL)
426 if (options.authorized_principals_command == NULL)
428 if (options.authorized_principals_command_user == NULL) {
429 error("No user for AuthorizedPrincipalsCommand specified, "
435 * NB. all returns later this function should go via "out" to
436 * ensure the original SIGCHLD handler is restored properly.
438 osigchld = signal(SIGCHLD, SIG_DFL);
440 /* Prepare and verify the user for the command */
441 username = percent_expand(options.authorized_principals_command_user,
442 "u", user_pw->pw_name, (char *)NULL);
443 runas_pw = getpwnam(username);
444 if (runas_pw == NULL) {
445 error("AuthorizedPrincipalsCommandUser \"%s\" not found: %s",
446 username, strerror(errno));
450 /* Turn the command into an argument vector */
451 if (argv_split(options.authorized_principals_command, &ac, &av) != 0) {
452 error("AuthorizedPrincipalsCommand \"%s\" contains "
453 "invalid quotes", command);
457 error("AuthorizedPrincipalsCommand \"%s\" yielded no arguments",
461 if ((ca_fp = sshkey_fingerprint(cert->signature_key,
462 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
463 error("%s: sshkey_fingerprint failed", __func__);
466 if ((key_fp = sshkey_fingerprint(key,
467 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
468 error("%s: sshkey_fingerprint failed", __func__);
471 if ((r = sshkey_to_base64(cert->signature_key, &catext)) != 0) {
472 error("%s: sshkey_to_base64 failed: %s", __func__, ssh_err(r));
475 if ((r = sshkey_to_base64(key, &keytext)) != 0) {
476 error("%s: sshkey_to_base64 failed: %s", __func__, ssh_err(r));
479 snprintf(serial_s, sizeof(serial_s), "%llu",
480 (unsigned long long)cert->serial);
481 snprintf(uidstr, sizeof(uidstr), "%llu",
482 (unsigned long long)user_pw->pw_uid);
483 for (i = 1; i < ac; i++) {
484 tmp = percent_expand(av[i],
486 "u", user_pw->pw_name,
487 "h", user_pw->pw_dir,
488 "t", sshkey_ssh_name(key),
489 "T", sshkey_ssh_name(cert->signature_key),
498 fatal("%s: percent_expand failed", __func__);
502 /* Prepare a printable command for logs, etc. */
503 command = argv_assemble(ac, av);
505 if ((pid = subprocess("AuthorizedPrincipalsCommand", runas_pw, command,
507 SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD)) == 0)
511 temporarily_use_uid(runas_pw);
513 ok = process_principals(ssh, f, "(command)", cert, authoptsp);
518 if (exited_cleanly(pid, "AuthorizedPrincipalsCommand", command, 0) != 0)
521 /* Read completed successfully */
522 found_principal = ok;
526 signal(SIGCHLD, osigchld);
527 for (i = 0; i < ac; i++)
538 return found_principal;
542 skip_space(char **cpp)
546 for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
552 * Advanced *cpp past the end of key options, defined as the first unquoted
553 * whitespace character. Returns 0 on success or -1 on failure (e.g.
554 * unterminated quotes).
557 advance_past_options(char **cpp)
562 for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
563 if (*cp == '\\' && cp[1] == '"')
564 cp++; /* Skip both */
569 /* return failure for unterminated quotes */
570 return (*cp == '\0' && quoted) ? -1 : 0;
574 * Check a single line of an authorized_keys-format file. Returns 0 if key
575 * matches, -1 otherwise. Will return key/cert options via *authoptsp
576 * on success. "loc" is used as file/line location in log messages.
579 check_authkey_line(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
580 char *cp, const char *loc, struct sshauthopt **authoptsp)
582 int want_keytype = sshkey_is_cert(key) ? KEY_UNSPEC : key->type;
583 struct sshkey *found = NULL;
584 struct sshauthopt *keyopts = NULL, *certopts = NULL, *finalopts = NULL;
585 char *key_options = NULL, *fp = NULL;
586 const char *reason = NULL;
589 if (authoptsp != NULL)
592 if ((found = sshkey_new(want_keytype)) == NULL) {
593 debug3("%s: keytype %d failed", __func__, want_keytype);
597 /* XXX djm: peek at key type in line and skip if unwanted */
599 if (sshkey_read(found, &cp) != 0) {
600 /* no key? check for options */
601 debug2("%s: check options: '%s'", loc, cp);
603 if (advance_past_options(&cp) != 0) {
604 reason = "invalid key option string";
608 if (sshkey_read(found, &cp) != 0) {
609 /* still no key? advance to next line*/
610 debug2("%s: advance: '%s'", loc, cp);
614 /* Parse key options now; we need to know if this is a CA key */
615 if ((keyopts = sshauthopt_parse(key_options, &reason)) == NULL) {
616 debug("%s: bad key options: %s", loc, reason);
617 auth_debug_add("%s: bad key options: %s", loc, reason);
620 /* Ignore keys that don't match or incorrectly marked as CAs */
621 if (sshkey_is_cert(key)) {
622 /* Certificate; check signature key against CA */
623 if (!sshkey_equal(found, key->cert->signature_key) ||
624 !keyopts->cert_authority)
627 /* Plain key: check it against key found in file */
628 if (!sshkey_equal(found, key) || keyopts->cert_authority)
632 /* We have a candidate key, perform authorisation checks */
633 if ((fp = sshkey_fingerprint(found,
634 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
635 fatal("%s: fingerprint failed", __func__);
637 debug("%s: matching %s found: %s %s", loc,
638 sshkey_is_cert(key) ? "CA" : "key", sshkey_type(found), fp);
640 if (auth_authorise_keyopts(ssh, pw, keyopts,
641 sshkey_is_cert(key), loc) != 0) {
642 reason = "Refused by key options";
645 /* That's all we need for plain keys. */
646 if (!sshkey_is_cert(key)) {
647 verbose("Accepted key %s %s found at %s",
648 sshkey_type(found), fp, loc);
655 * Additional authorisation for certificates.
658 /* Parse and check options present in certificate */
659 if ((certopts = sshauthopt_from_cert(key)) == NULL) {
660 reason = "Invalid certificate options";
663 if (auth_authorise_keyopts(ssh, pw, certopts, 0, loc) != 0) {
664 reason = "Refused by certificate options";
667 if ((finalopts = sshauthopt_merge(keyopts, certopts, &reason)) == NULL)
671 * If the user has specified a list of principals as
672 * a key option, then prefer that list to matching
673 * their username in the certificate principals list.
675 if (keyopts->cert_principals != NULL &&
676 !match_principals_option(keyopts->cert_principals, key->cert)) {
677 reason = "Certificate does not contain an authorized principal";
680 if (sshkey_cert_check_authority(key, 0, 0,
681 keyopts->cert_principals == NULL ? pw->pw_name : NULL, &reason) != 0)
684 verbose("Accepted certificate ID \"%s\" (serial %llu) "
685 "signed by CA %s %s found at %s",
687 (unsigned long long)key->cert->serial,
688 sshkey_type(found), fp, loc);
691 if (finalopts == NULL)
692 fatal("%s: internal error: missing options", __func__);
693 if (authoptsp != NULL) {
694 *authoptsp = finalopts;
703 auth_debug_add("%s", reason);
706 sshauthopt_free(keyopts);
707 sshauthopt_free(certopts);
708 sshauthopt_free(finalopts);
714 * Checks whether key is allowed in authorized_keys-format file,
715 * returns 1 if the key is allowed or 0 otherwise.
718 check_authkeys_file(struct ssh *ssh, struct passwd *pw, FILE *f,
719 char *file, struct sshkey *key, struct sshauthopt **authoptsp)
721 char *cp, *line = NULL, loc[256];
726 if (authoptsp != NULL)
729 while (getline(&line, &linesize, f) != -1) {
731 /* Always consume entire file */
735 /* Skip leading whitespace, empty and comment lines. */
738 if (!*cp || *cp == '\n' || *cp == '#')
740 snprintf(loc, sizeof(loc), "%.200s:%lu", file, linenum);
741 if (check_authkey_line(ssh, pw, key, cp, loc, authoptsp) == 0)
748 /* Authenticate a certificate key against TrustedUserCAKeys */
750 user_cert_trusted_ca(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
751 struct sshauthopt **authoptsp)
753 char *ca_fp, *principals_file = NULL;
755 struct sshauthopt *principals_opts = NULL, *cert_opts = NULL;
756 struct sshauthopt *final_opts = NULL;
757 int r, ret = 0, found_principal = 0, use_authorized_principals;
759 if (authoptsp != NULL)
762 if (!sshkey_is_cert(key) || options.trusted_user_ca_keys == NULL)
765 if ((ca_fp = sshkey_fingerprint(key->cert->signature_key,
766 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
769 if ((r = sshkey_in_file(key->cert->signature_key,
770 options.trusted_user_ca_keys, 1, 0)) != 0) {
771 debug2("%s: CA %s %s is not listed in %s: %s", __func__,
772 sshkey_type(key->cert->signature_key), ca_fp,
773 options.trusted_user_ca_keys, ssh_err(r));
777 * If AuthorizedPrincipals is in use, then compare the certificate
778 * principals against the names in that file rather than matching
779 * against the username.
781 if ((principals_file = authorized_principals_file(pw)) != NULL) {
782 if (match_principals_file(ssh, pw, principals_file,
783 key->cert, &principals_opts))
786 /* Try querying command if specified */
787 if (!found_principal && match_principals_command(ssh, pw, key,
790 /* If principals file or command is specified, then require a match */
791 use_authorized_principals = principals_file != NULL ||
792 options.authorized_principals_command != NULL;
793 if (!found_principal && use_authorized_principals) {
794 reason = "Certificate does not contain an authorized principal";
797 if (use_authorized_principals && principals_opts == NULL)
798 fatal("%s: internal error: missing principals_opts", __func__);
799 if (sshkey_cert_check_authority(key, 0, 1,
800 use_authorized_principals ? NULL : pw->pw_name, &reason) != 0)
803 /* Check authority from options in key and from principals file/cmd */
804 if ((cert_opts = sshauthopt_from_cert(key)) == NULL) {
805 reason = "Invalid certificate options";
808 if (auth_authorise_keyopts(ssh, pw, cert_opts, 0, "cert") != 0) {
809 reason = "Refused by certificate options";
812 if (principals_opts == NULL) {
813 final_opts = cert_opts;
816 if (auth_authorise_keyopts(ssh, pw, principals_opts, 0,
817 "principals") != 0) {
818 reason = "Refused by certificate principals options";
821 if ((final_opts = sshauthopt_merge(principals_opts,
822 cert_opts, &reason)) == NULL) {
825 auth_debug_add("%s", reason);
831 verbose("Accepted certificate ID \"%s\" (serial %llu) signed by "
832 "%s CA %s via %s", key->cert->key_id,
833 (unsigned long long)key->cert->serial,
834 sshkey_type(key->cert->signature_key), ca_fp,
835 options.trusted_user_ca_keys);
836 if (authoptsp != NULL) {
837 *authoptsp = final_opts;
842 sshauthopt_free(principals_opts);
843 sshauthopt_free(cert_opts);
844 sshauthopt_free(final_opts);
845 free(principals_file);
851 * Checks whether key is allowed in file.
852 * returns 1 if the key is allowed or 0 otherwise.
855 user_key_allowed2(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
856 char *file, struct sshauthopt **authoptsp)
861 if (authoptsp != NULL)
864 /* Temporarily use the user's uid. */
865 temporarily_use_uid(pw);
867 debug("trying public key file %s", file);
868 if ((f = auth_openkeyfile(file, pw, options.strict_modes)) != NULL) {
869 found_key = check_authkeys_file(ssh, pw, f, file,
879 * Checks whether key is allowed in output of command.
880 * returns 1 if the key is allowed or 0 otherwise.
883 user_key_command_allowed2(struct ssh *ssh, struct passwd *user_pw,
884 struct sshkey *key, struct sshauthopt **authoptsp)
886 struct passwd *runas_pw = NULL;
888 int r, ok, found_key = 0;
889 int i, uid_swapped = 0, ac = 0;
891 char *username = NULL, *key_fp = NULL, *keytext = NULL;
892 char uidstr[32], *tmp, *command = NULL, **av = NULL;
893 void (*osigchld)(int);
895 if (authoptsp != NULL)
897 if (options.authorized_keys_command == NULL)
899 if (options.authorized_keys_command_user == NULL) {
900 error("No user for AuthorizedKeysCommand specified, skipping");
905 * NB. all returns later this function should go via "out" to
906 * ensure the original SIGCHLD handler is restored properly.
908 osigchld = signal(SIGCHLD, SIG_DFL);
910 /* Prepare and verify the user for the command */
911 username = percent_expand(options.authorized_keys_command_user,
912 "u", user_pw->pw_name, (char *)NULL);
913 runas_pw = getpwnam(username);
914 if (runas_pw == NULL) {
915 error("AuthorizedKeysCommandUser \"%s\" not found: %s",
916 username, strerror(errno));
920 /* Prepare AuthorizedKeysCommand */
921 if ((key_fp = sshkey_fingerprint(key, options.fingerprint_hash,
922 SSH_FP_DEFAULT)) == NULL) {
923 error("%s: sshkey_fingerprint failed", __func__);
926 if ((r = sshkey_to_base64(key, &keytext)) != 0) {
927 error("%s: sshkey_to_base64 failed: %s", __func__, ssh_err(r));
931 /* Turn the command into an argument vector */
932 if (argv_split(options.authorized_keys_command, &ac, &av) != 0) {
933 error("AuthorizedKeysCommand \"%s\" contains invalid quotes",
938 error("AuthorizedKeysCommand \"%s\" yielded no arguments",
942 snprintf(uidstr, sizeof(uidstr), "%llu",
943 (unsigned long long)user_pw->pw_uid);
944 for (i = 1; i < ac; i++) {
945 tmp = percent_expand(av[i],
947 "u", user_pw->pw_name,
948 "h", user_pw->pw_dir,
949 "t", sshkey_ssh_name(key),
954 fatal("%s: percent_expand failed", __func__);
958 /* Prepare a printable command for logs, etc. */
959 command = argv_assemble(ac, av);
962 * If AuthorizedKeysCommand was run without arguments
963 * then fall back to the old behaviour of passing the
964 * target username as a single argument.
967 av = xreallocarray(av, ac + 2, sizeof(*av));
968 av[1] = xstrdup(user_pw->pw_name);
970 /* Fix up command too, since it is used in log messages */
972 xasprintf(&command, "%s %s", av[0], av[1]);
975 if ((pid = subprocess("AuthorizedKeysCommand", runas_pw, command,
977 SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD)) == 0)
981 temporarily_use_uid(runas_pw);
983 ok = check_authkeys_file(ssh, user_pw, f,
984 options.authorized_keys_command, key, authoptsp);
989 if (exited_cleanly(pid, "AuthorizedKeysCommand", command, 0) != 0)
992 /* Read completed successfully */
997 signal(SIGCHLD, osigchld);
998 for (i = 0; i < ac; i++)
1011 * Check whether key authenticates and authorises the user.
1014 user_key_allowed(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
1015 int auth_attempt, struct sshauthopt **authoptsp)
1019 struct sshauthopt *opts = NULL;
1020 if (authoptsp != NULL)
1023 if (auth_key_is_revoked(key))
1025 if (sshkey_is_cert(key) &&
1026 auth_key_is_revoked(key->cert->signature_key))
1029 if ((success = user_cert_trusted_ca(ssh, pw, key, &opts)) != 0)
1031 sshauthopt_free(opts);
1034 if ((success = user_key_command_allowed2(ssh, pw, key, &opts)) != 0)
1036 sshauthopt_free(opts);
1039 for (i = 0; !success && i < options.num_authkeys_files; i++) {
1040 if (strcasecmp(options.authorized_keys_files[i], "none") == 0)
1042 file = expand_authorized_keys(
1043 options.authorized_keys_files[i], pw);
1044 success = user_key_allowed2(ssh, pw, key, file, &opts);
1049 if (success && authoptsp != NULL) {
1053 sshauthopt_free(opts);
1057 Authmethod method_pubkey = {
1060 &options.pubkey_authentication