1 /* $OpenBSD: auth2-pubkey.c,v 1.77 2018/03/03 03:15:51 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;
93 struct sshkey *key = NULL;
94 char *pkalg, *userstyle = NULL, *key_s = NULL, *ca_s = NULL;
95 u_char *pkblob, *sig, have_sig;
98 int authenticated = 0;
99 struct sshauthopt *authopts = NULL;
101 if (!authctxt->valid) {
102 debug2("%s: disabled because of invalid user", __func__);
105 if ((r = sshpkt_get_u8(ssh, &have_sig)) != 0 ||
106 (r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 ||
107 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0)
108 fatal("%s: parse request failed: %s", __func__, ssh_err(r));
109 pktype = sshkey_type_from_name(pkalg);
110 if (pktype == KEY_UNSPEC) {
111 /* this is perfectly legal */
112 logit("%s: unsupported public key algorithm: %s",
116 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
117 error("%s: could not parse key: %s", __func__, ssh_err(r));
121 error("%s: cannot decode key: %s", __func__, pkalg);
124 if (key->type != pktype) {
125 error("%s: type mismatch for decoded key "
126 "(received %d, expected %d)", __func__, key->type, pktype);
129 if (sshkey_type_plain(key->type) == KEY_RSA &&
130 (ssh->compat & SSH_BUG_RSASIGMD5) != 0) {
131 logit("Refusing RSA key because client uses unsafe "
135 if (auth2_key_already_used(authctxt, key)) {
136 logit("refusing previously-used %s key", sshkey_type(key));
139 if (match_pattern_list(sshkey_ssh_name(key),
140 options.pubkey_key_types, 0) != 1) {
141 logit("%s: key type %s not in PubkeyAcceptedKeyTypes",
142 __func__, sshkey_ssh_name(key));
146 key_s = format_key(key);
147 if (sshkey_is_cert(key))
148 ca_s = format_key(key->cert->signature_key);
151 debug3("%s: have %s signature for %s%s%s",
152 __func__, pkalg, key_s,
153 ca_s == NULL ? "" : " CA ",
154 ca_s == NULL ? "" : ca_s);
155 if ((r = sshpkt_get_string(ssh, &sig, &slen)) != 0 ||
156 (r = sshpkt_get_end(ssh)) != 0)
157 fatal("%s: %s", __func__, ssh_err(r));
158 if ((b = sshbuf_new()) == NULL)
159 fatal("%s: sshbuf_new failed", __func__);
160 if (ssh->compat & SSH_OLD_SESSIONID) {
161 if ((r = sshbuf_put(b, session_id2,
162 session_id2_len)) != 0)
163 fatal("%s: sshbuf_put session id: %s",
164 __func__, ssh_err(r));
166 if ((r = sshbuf_put_string(b, session_id2,
167 session_id2_len)) != 0)
168 fatal("%s: sshbuf_put_string session id: %s",
169 __func__, ssh_err(r));
171 /* reconstruct packet */
172 xasprintf(&userstyle, "%s%s%s", authctxt->user,
173 authctxt->style ? ":" : "",
174 authctxt->style ? authctxt->style : "");
175 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
176 (r = sshbuf_put_cstring(b, userstyle)) != 0 ||
177 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
178 (r = sshbuf_put_cstring(b, "publickey")) != 0 ||
179 (r = sshbuf_put_u8(b, have_sig)) != 0 ||
180 (r = sshbuf_put_cstring(b, pkalg) != 0) ||
181 (r = sshbuf_put_string(b, pkblob, blen)) != 0)
182 fatal("%s: build packet failed: %s",
183 __func__, ssh_err(r));
185 sshbuf_dump(b, stderr);
188 /* test for correct signature */
190 if (PRIVSEP(user_key_allowed(ssh, pw, key, 1, &authopts)) &&
191 PRIVSEP(sshkey_verify(key, sig, slen, sshbuf_ptr(b),
192 sshbuf_len(b), NULL, ssh->compat)) == 0) {
197 auth2_record_key(authctxt, authenticated, key);
199 debug("%s: test pkalg %s pkblob %s%s%s",
200 __func__, pkalg, key_s,
201 ca_s == NULL ? "" : " CA ",
202 ca_s == NULL ? "" : ca_s);
204 if ((r = sshpkt_get_end(ssh)) != 0)
205 fatal("%s: %s", __func__, ssh_err(r));
207 /* XXX fake reply and always send PK_OK ? */
209 * XXX this allows testing whether a user is allowed
210 * to login: if you happen to have a valid pubkey this
211 * message is sent. the message is NEVER sent at all
212 * if a user is not allowed to login. is this an
215 if (PRIVSEP(user_key_allowed(ssh, pw, key, 0, NULL))) {
216 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_PK_OK))
218 (r = sshpkt_put_cstring(ssh, pkalg)) != 0 ||
219 (r = sshpkt_put_string(ssh, pkblob, blen)) != 0 ||
220 (r = sshpkt_send(ssh)) != 0)
221 fatal("%s: %s", __func__, ssh_err(r));
222 ssh_packet_write_wait(ssh);
223 authctxt->postponed = 1;
227 if (authenticated == 1 && auth_activate_options(ssh, authopts) != 0) {
228 debug("%s: key options inconsistent with existing", __func__);
231 debug2("%s: authenticated %d pkalg %s", __func__, authenticated, pkalg);
233 sshauthopt_free(authopts);
240 return authenticated;
244 match_principals_option(const char *principal_list, struct sshkey_cert *cert)
249 /* XXX percent_expand() sequences for authorized_principals? */
251 for (i = 0; i < cert->nprincipals; i++) {
252 if ((result = match_list(cert->principals[i],
253 principal_list, NULL)) != NULL) {
254 debug3("matched principal from key options \"%.100s\"",
264 * Process a single authorized_principals format line. Returns 0 and sets
265 * authoptsp is principal is authorised, -1 otherwise. "loc" is used as a
266 * log preamble for file/line information.
269 check_principals_line(struct ssh *ssh, char *cp, const struct sshkey_cert *cert,
270 const char *loc, struct sshauthopt **authoptsp)
273 char *ep, *line_opts;
274 const char *reason = NULL;
275 struct sshauthopt *opts = NULL;
277 if (authoptsp != NULL)
280 /* Trim trailing whitespace. */
281 ep = cp + strlen(cp) - 1;
282 while (ep > cp && (*ep == '\n' || *ep == ' ' || *ep == '\t'))
286 * If the line has internal whitespace then assume it has
290 if ((ep = strrchr(cp, ' ')) != NULL ||
291 (ep = strrchr(cp, '\t')) != NULL) {
292 for (; *ep == ' ' || *ep == '\t'; ep++)
297 if ((opts = sshauthopt_parse(line_opts, &reason)) == NULL) {
298 debug("%s: bad principals options: %s", loc, reason);
299 auth_debug_add("%s: bad principals options: %s", loc, reason);
302 /* Check principals in cert against those on line */
303 for (i = 0; i < cert->nprincipals; i++) {
304 if (strcmp(cp, cert->principals[i]) != 0)
306 debug3("%s: matched principal \"%.100s\"",
307 loc, cert->principals[i]);
310 if (found && authoptsp != NULL) {
314 sshauthopt_free(opts);
315 return found ? 0 : -1;
319 process_principals(struct ssh *ssh, FILE *f, const char *file,
320 const struct sshkey_cert *cert, struct sshauthopt **authoptsp)
322 char loc[256], line[SSH_MAX_PUBKEY_BYTES], *cp, *ep;
324 u_int found_principal = 0;
326 if (authoptsp != NULL)
329 while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
330 /* Always consume entire input */
334 /* Skip leading whitespace. */
335 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
337 /* Skip blank and comment lines. */
338 if ((ep = strchr(cp, '#')) != NULL)
340 if (!*cp || *cp == '\n')
343 snprintf(loc, sizeof(loc), "%.200s:%lu", file, linenum);
344 if (check_principals_line(ssh, cp, cert, loc, authoptsp) == 0)
347 return found_principal;
350 /* XXX remove pw args here and elsewhere once ssh->authctxt is guaranteed */
353 match_principals_file(struct ssh *ssh, struct passwd *pw, char *file,
354 struct sshkey_cert *cert, struct sshauthopt **authoptsp)
359 if (authoptsp != NULL)
362 temporarily_use_uid(pw);
363 debug("trying authorized principals file %s", file);
364 if ((f = auth_openprincipals(file, pw, options.strict_modes)) == NULL) {
368 success = process_principals(ssh, f, file, cert, authoptsp);
375 * Checks whether principal is allowed in output of command.
376 * returns 1 if the principal is allowed or 0 otherwise.
379 match_principals_command(struct ssh *ssh, struct passwd *user_pw,
380 const struct sshkey *key, struct sshauthopt **authoptsp)
382 struct passwd *runas_pw = NULL;
383 const struct sshkey_cert *cert = key->cert;
385 int r, ok, found_principal = 0;
386 int i, ac = 0, uid_swapped = 0;
388 char *tmp, *username = NULL, *command = NULL, **av = NULL;
389 char *ca_fp = NULL, *key_fp = NULL, *catext = NULL, *keytext = NULL;
391 void (*osigchld)(int);
393 if (authoptsp != NULL)
395 if (options.authorized_principals_command == NULL)
397 if (options.authorized_principals_command_user == NULL) {
398 error("No user for AuthorizedPrincipalsCommand specified, "
404 * NB. all returns later this function should go via "out" to
405 * ensure the original SIGCHLD handler is restored properly.
407 osigchld = signal(SIGCHLD, SIG_DFL);
409 /* Prepare and verify the user for the command */
410 username = percent_expand(options.authorized_principals_command_user,
411 "u", user_pw->pw_name, (char *)NULL);
412 runas_pw = getpwnam(username);
413 if (runas_pw == NULL) {
414 error("AuthorizedPrincipalsCommandUser \"%s\" not found: %s",
415 username, strerror(errno));
419 /* Turn the command into an argument vector */
420 if (argv_split(options.authorized_principals_command, &ac, &av) != 0) {
421 error("AuthorizedPrincipalsCommand \"%s\" contains "
422 "invalid quotes", command);
426 error("AuthorizedPrincipalsCommand \"%s\" yielded no arguments",
430 if ((ca_fp = sshkey_fingerprint(cert->signature_key,
431 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
432 error("%s: sshkey_fingerprint failed", __func__);
435 if ((key_fp = sshkey_fingerprint(key,
436 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
437 error("%s: sshkey_fingerprint failed", __func__);
440 if ((r = sshkey_to_base64(cert->signature_key, &catext)) != 0) {
441 error("%s: sshkey_to_base64 failed: %s", __func__, ssh_err(r));
444 if ((r = sshkey_to_base64(key, &keytext)) != 0) {
445 error("%s: sshkey_to_base64 failed: %s", __func__, ssh_err(r));
448 snprintf(serial_s, sizeof(serial_s), "%llu",
449 (unsigned long long)cert->serial);
450 for (i = 1; i < ac; i++) {
451 tmp = percent_expand(av[i],
452 "u", user_pw->pw_name,
453 "h", user_pw->pw_dir,
454 "t", sshkey_ssh_name(key),
455 "T", sshkey_ssh_name(cert->signature_key),
464 fatal("%s: percent_expand failed", __func__);
468 /* Prepare a printable command for logs, etc. */
469 command = argv_assemble(ac, av);
471 if ((pid = subprocess("AuthorizedPrincipalsCommand", runas_pw, command,
473 SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD)) == 0)
477 temporarily_use_uid(runas_pw);
479 ok = process_principals(ssh, f, "(command)", cert, authoptsp);
484 if (exited_cleanly(pid, "AuthorizedPrincipalsCommand", command, 0) != 0)
487 /* Read completed successfully */
488 found_principal = ok;
492 signal(SIGCHLD, osigchld);
493 for (i = 0; i < ac; i++)
504 return found_principal;
508 skip_space(char **cpp)
512 for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
518 * Advanced *cpp past the end of key options, defined as the first unquoted
519 * whitespace character. Returns 0 on success or -1 on failure (e.g.
520 * unterminated quotes).
523 advance_past_options(char **cpp)
528 for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
529 if (*cp == '\\' && cp[1] == '"')
530 cp++; /* Skip both */
535 /* return failure for unterminated quotes */
536 return (*cp == '\0' && quoted) ? -1 : 0;
540 * Check a single line of an authorized_keys-format file. Returns 0 if key
541 * matches, -1 otherwise. Will return key/cert options via *authoptsp
542 * on success. "loc" is used as file/line location in log messages.
545 check_authkey_line(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
546 char *cp, const char *loc, struct sshauthopt **authoptsp)
548 int want_keytype = sshkey_is_cert(key) ? KEY_UNSPEC : key->type;
549 struct sshkey *found = NULL;
550 struct sshauthopt *keyopts = NULL, *certopts = NULL, *finalopts = NULL;
551 char *key_options = NULL, *fp = NULL;
552 const char *reason = NULL;
555 if (authoptsp != NULL)
558 if ((found = sshkey_new(want_keytype)) == NULL) {
559 debug3("%s: keytype %d failed", __func__, want_keytype);
563 /* XXX djm: peek at key type in line and skip if unwanted */
565 if (sshkey_read(found, &cp) != 0) {
566 /* no key? check for options */
567 debug2("%s: check options: '%s'", loc, cp);
569 if (advance_past_options(&cp) != 0) {
570 reason = "invalid key option string";
574 if (sshkey_read(found, &cp) != 0) {
575 /* still no key? advance to next line*/
576 debug2("%s: advance: '%s'", loc, cp);
580 /* Parse key options now; we need to know if this is a CA key */
581 if ((keyopts = sshauthopt_parse(key_options, &reason)) == NULL) {
582 debug("%s: bad key options: %s", loc, reason);
583 auth_debug_add("%s: bad key options: %s", loc, reason);
586 /* Ignore keys that don't match or incorrectly marked as CAs */
587 if (sshkey_is_cert(key)) {
588 /* Certificate; check signature key against CA */
589 if (!sshkey_equal(found, key->cert->signature_key) ||
590 !keyopts->cert_authority)
593 /* Plain key: check it against key found in file */
594 if (!sshkey_equal(found, key) || keyopts->cert_authority)
598 /* We have a candidate key, perform authorisation checks */
599 if ((fp = sshkey_fingerprint(found,
600 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
601 fatal("%s: fingerprint failed", __func__);
603 debug("%s: matching %s found: %s %s", loc,
604 sshkey_is_cert(key) ? "CA" : "key", sshkey_type(found), fp);
606 if (auth_authorise_keyopts(ssh, pw, keyopts,
607 sshkey_is_cert(key), loc) != 0) {
608 reason = "Refused by key options";
611 /* That's all we need for plain keys. */
612 if (!sshkey_is_cert(key)) {
613 verbose("Accepted key %s %s found at %s",
614 sshkey_type(found), fp, loc);
621 * Additional authorisation for certificates.
624 /* Parse and check options present in certificate */
625 if ((certopts = sshauthopt_from_cert(key)) == NULL) {
626 reason = "Invalid certificate options";
629 if (auth_authorise_keyopts(ssh, pw, certopts, 0, loc) != 0) {
630 reason = "Refused by certificate options";
633 if ((finalopts = sshauthopt_merge(keyopts, certopts, &reason)) == NULL)
637 * If the user has specified a list of principals as
638 * a key option, then prefer that list to matching
639 * their username in the certificate principals list.
641 if (keyopts->cert_principals != NULL &&
642 !match_principals_option(keyopts->cert_principals, key->cert)) {
643 reason = "Certificate does not contain an authorized principal";
646 if (sshkey_cert_check_authority(key, 0, 0,
647 keyopts->cert_principals == NULL ? pw->pw_name : NULL, &reason) != 0)
650 verbose("Accepted certificate ID \"%s\" (serial %llu) "
651 "signed by CA %s %s found at %s",
653 (unsigned long long)key->cert->serial,
654 sshkey_type(found), fp, loc);
657 if (finalopts == NULL)
658 fatal("%s: internal error: missing options", __func__);
659 if (authoptsp != NULL) {
660 *authoptsp = finalopts;
669 auth_debug_add("%s", reason);
672 sshauthopt_free(keyopts);
673 sshauthopt_free(certopts);
674 sshauthopt_free(finalopts);
680 * Checks whether key is allowed in authorized_keys-format file,
681 * returns 1 if the key is allowed or 0 otherwise.
684 check_authkeys_file(struct ssh *ssh, struct passwd *pw, FILE *f,
685 char *file, struct sshkey *key, struct sshauthopt **authoptsp)
687 char *cp, line[SSH_MAX_PUBKEY_BYTES], loc[256];
691 if (authoptsp != NULL)
694 while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
695 /* Always consume entire file */
699 /* Skip leading whitespace, empty and comment lines. */
702 if (!*cp || *cp == '\n' || *cp == '#')
704 snprintf(loc, sizeof(loc), "%.200s:%lu", file, linenum);
705 if (check_authkey_line(ssh, pw, key, cp, loc, authoptsp) == 0)
711 /* Authenticate a certificate key against TrustedUserCAKeys */
713 user_cert_trusted_ca(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
714 struct sshauthopt **authoptsp)
716 char *ca_fp, *principals_file = NULL;
718 struct sshauthopt *principals_opts = NULL, *cert_opts = NULL;
719 struct sshauthopt *final_opts = NULL;
720 int r, ret = 0, found_principal = 0, use_authorized_principals;
722 if (authoptsp != NULL)
725 if (!sshkey_is_cert(key) || options.trusted_user_ca_keys == NULL)
728 if ((ca_fp = sshkey_fingerprint(key->cert->signature_key,
729 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
732 if ((r = sshkey_in_file(key->cert->signature_key,
733 options.trusted_user_ca_keys, 1, 0)) != 0) {
734 debug2("%s: CA %s %s is not listed in %s: %s", __func__,
735 sshkey_type(key->cert->signature_key), ca_fp,
736 options.trusted_user_ca_keys, ssh_err(r));
740 * If AuthorizedPrincipals is in use, then compare the certificate
741 * principals against the names in that file rather than matching
742 * against the username.
744 if ((principals_file = authorized_principals_file(pw)) != NULL) {
745 if (match_principals_file(ssh, pw, principals_file,
746 key->cert, &principals_opts))
749 /* Try querying command if specified */
750 if (!found_principal && match_principals_command(ssh, pw, key,
753 /* If principals file or command is specified, then require a match */
754 use_authorized_principals = principals_file != NULL ||
755 options.authorized_principals_command != NULL;
756 if (!found_principal && use_authorized_principals) {
757 reason = "Certificate does not contain an authorized principal";
760 if (use_authorized_principals && principals_opts == NULL)
761 fatal("%s: internal error: missing principals_opts", __func__);
762 if (sshkey_cert_check_authority(key, 0, 1,
763 use_authorized_principals ? NULL : pw->pw_name, &reason) != 0)
766 /* Check authority from options in key and from principals file/cmd */
767 if ((cert_opts = sshauthopt_from_cert(key)) == NULL) {
768 reason = "Invalid certificate options";
771 if (auth_authorise_keyopts(ssh, pw, cert_opts, 0, "cert") != 0) {
772 reason = "Refused by certificate options";
775 if (principals_opts == NULL) {
776 final_opts = cert_opts;
779 if (auth_authorise_keyopts(ssh, pw, principals_opts, 0,
780 "principals") != 0) {
781 reason = "Refused by certificate principals options";
784 if ((final_opts = sshauthopt_merge(principals_opts,
785 cert_opts, &reason)) == NULL) {
788 auth_debug_add("%s", reason);
794 verbose("Accepted certificate ID \"%s\" (serial %llu) signed by "
795 "%s CA %s via %s", key->cert->key_id,
796 (unsigned long long)key->cert->serial,
797 sshkey_type(key->cert->signature_key), ca_fp,
798 options.trusted_user_ca_keys);
799 if (authoptsp != NULL) {
800 *authoptsp = final_opts;
805 sshauthopt_free(principals_opts);
806 sshauthopt_free(cert_opts);
807 sshauthopt_free(final_opts);
808 free(principals_file);
814 * Checks whether key is allowed in file.
815 * returns 1 if the key is allowed or 0 otherwise.
818 user_key_allowed2(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
819 char *file, struct sshauthopt **authoptsp)
824 if (authoptsp != NULL)
827 /* Temporarily use the user's uid. */
828 temporarily_use_uid(pw);
830 debug("trying public key file %s", file);
831 if ((f = auth_openkeyfile(file, pw, options.strict_modes)) != NULL) {
832 found_key = check_authkeys_file(ssh, pw, f, file,
842 * Checks whether key is allowed in output of command.
843 * returns 1 if the key is allowed or 0 otherwise.
846 user_key_command_allowed2(struct ssh *ssh, struct passwd *user_pw,
847 struct sshkey *key, struct sshauthopt **authoptsp)
849 struct passwd *runas_pw = NULL;
851 int r, ok, found_key = 0;
852 int i, uid_swapped = 0, ac = 0;
854 char *username = NULL, *key_fp = NULL, *keytext = NULL;
855 char *tmp, *command = NULL, **av = NULL;
856 void (*osigchld)(int);
858 if (authoptsp != NULL)
860 if (options.authorized_keys_command == NULL)
862 if (options.authorized_keys_command_user == NULL) {
863 error("No user for AuthorizedKeysCommand specified, skipping");
868 * NB. all returns later this function should go via "out" to
869 * ensure the original SIGCHLD handler is restored properly.
871 osigchld = signal(SIGCHLD, SIG_DFL);
873 /* Prepare and verify the user for the command */
874 username = percent_expand(options.authorized_keys_command_user,
875 "u", user_pw->pw_name, (char *)NULL);
876 runas_pw = getpwnam(username);
877 if (runas_pw == NULL) {
878 error("AuthorizedKeysCommandUser \"%s\" not found: %s",
879 username, strerror(errno));
883 /* Prepare AuthorizedKeysCommand */
884 if ((key_fp = sshkey_fingerprint(key, options.fingerprint_hash,
885 SSH_FP_DEFAULT)) == NULL) {
886 error("%s: sshkey_fingerprint failed", __func__);
889 if ((r = sshkey_to_base64(key, &keytext)) != 0) {
890 error("%s: sshkey_to_base64 failed: %s", __func__, ssh_err(r));
894 /* Turn the command into an argument vector */
895 if (argv_split(options.authorized_keys_command, &ac, &av) != 0) {
896 error("AuthorizedKeysCommand \"%s\" contains invalid quotes",
901 error("AuthorizedKeysCommand \"%s\" yielded no arguments",
905 for (i = 1; i < ac; i++) {
906 tmp = percent_expand(av[i],
907 "u", user_pw->pw_name,
908 "h", user_pw->pw_dir,
909 "t", sshkey_ssh_name(key),
914 fatal("%s: percent_expand failed", __func__);
918 /* Prepare a printable command for logs, etc. */
919 command = argv_assemble(ac, av);
922 * If AuthorizedKeysCommand was run without arguments
923 * then fall back to the old behaviour of passing the
924 * target username as a single argument.
927 av = xreallocarray(av, ac + 2, sizeof(*av));
928 av[1] = xstrdup(user_pw->pw_name);
930 /* Fix up command too, since it is used in log messages */
932 xasprintf(&command, "%s %s", av[0], av[1]);
935 if ((pid = subprocess("AuthorizedKeysCommand", runas_pw, command,
937 SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD)) == 0)
941 temporarily_use_uid(runas_pw);
943 ok = check_authkeys_file(ssh, user_pw, f,
944 options.authorized_keys_command, key, authoptsp);
949 if (exited_cleanly(pid, "AuthorizedKeysCommand", command, 0) != 0)
952 /* Read completed successfully */
957 signal(SIGCHLD, osigchld);
958 for (i = 0; i < ac; i++)
971 * Check whether key authenticates and authorises the user.
974 user_key_allowed(struct ssh *ssh, struct passwd *pw, struct sshkey *key,
975 int auth_attempt, struct sshauthopt **authoptsp)
979 struct sshauthopt *opts = NULL;
980 if (authoptsp != NULL)
983 if (auth_key_is_revoked(key))
985 if (sshkey_is_cert(key) &&
986 auth_key_is_revoked(key->cert->signature_key))
989 if ((success = user_cert_trusted_ca(ssh, pw, key, &opts)) != 0)
991 sshauthopt_free(opts);
994 if ((success = user_key_command_allowed2(ssh, pw, key, &opts)) != 0)
996 sshauthopt_free(opts);
999 for (i = 0; !success && i < options.num_authkeys_files; i++) {
1000 if (strcasecmp(options.authorized_keys_files[i], "none") == 0)
1002 file = expand_authorized_keys(
1003 options.authorized_keys_files[i], pw);
1004 success = user_key_allowed2(ssh, pw, key, file, &opts);
1009 if (success && authoptsp != NULL) {
1013 sshauthopt_free(opts);
1017 Authmethod method_pubkey = {
1020 &options.pubkey_authentication