1 /* $OpenBSD: auth2-pubkey.c,v 1.60 2016/11/30 02:57:40 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>
58 #include "pathnames.h"
60 #include "auth-options.h"
65 #include "monitor_wrap.h"
69 #include "channels.h" /* XXX for session.h */
70 #include "session.h" /* XXX for child_set_env(); refactor? */
73 extern ServerOptions options;
74 extern u_char *session_id2;
75 extern u_int session_id2_len;
78 userauth_pubkey(Authctxt *authctxt)
82 char *pkalg, *userstyle, *fp = NULL;
84 u_int alen, blen, slen;
86 int authenticated = 0;
88 if (!authctxt->valid) {
89 debug2("%s: disabled because of invalid user", __func__);
92 have_sig = packet_get_char();
93 if (datafellows & SSH_BUG_PKAUTH) {
94 debug2("%s: SSH_BUG_PKAUTH", __func__);
95 /* no explicit pkalg given */
96 pkblob = packet_get_string(&blen);
98 buffer_append(&b, pkblob, blen);
99 /* so we have to extract the pkalg from the pkblob */
100 pkalg = buffer_get_string(&b, &alen);
103 pkalg = packet_get_string(&alen);
104 pkblob = packet_get_string(&blen);
106 pktype = key_type_from_name(pkalg);
107 if (pktype == KEY_UNSPEC) {
108 /* this is perfectly legal */
109 logit("%s: unsupported public key algorithm: %s",
113 key = key_from_blob(pkblob, blen);
115 error("%s: cannot decode key: %s", __func__, pkalg);
118 if (key->type != pktype) {
119 error("%s: type mismatch for decoded key "
120 "(received %d, expected %d)", __func__, key->type, pktype);
123 if (key_type_plain(key->type) == KEY_RSA &&
124 (datafellows & SSH_BUG_RSASIGMD5) != 0) {
125 logit("Refusing RSA key because client uses unsafe "
129 fp = sshkey_fingerprint(key, options.fingerprint_hash, SSH_FP_DEFAULT);
130 if (auth2_userkey_already_used(authctxt, key)) {
131 logit("refusing previously-used %s key", key_type(key));
134 if (match_pattern_list(sshkey_ssh_name(key),
135 options.pubkey_key_types, 0) != 1) {
136 logit("%s: key type %s not in PubkeyAcceptedKeyTypes",
137 __func__, sshkey_ssh_name(key));
142 debug3("%s: have signature for %s %s",
143 __func__, sshkey_type(key), fp);
144 sig = packet_get_string(&slen);
147 if (datafellows & SSH_OLD_SESSIONID) {
148 buffer_append(&b, session_id2, session_id2_len);
150 buffer_put_string(&b, session_id2, session_id2_len);
152 /* reconstruct packet */
153 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
154 xasprintf(&userstyle, "%s%s%s", authctxt->user,
155 authctxt->style ? ":" : "",
156 authctxt->style ? authctxt->style : "");
157 buffer_put_cstring(&b, userstyle);
159 buffer_put_cstring(&b,
160 datafellows & SSH_BUG_PKSERVICE ?
163 if (datafellows & SSH_BUG_PKAUTH) {
164 buffer_put_char(&b, have_sig);
166 buffer_put_cstring(&b, "publickey");
167 buffer_put_char(&b, have_sig);
168 buffer_put_cstring(&b, pkalg);
170 buffer_put_string(&b, pkblob, blen);
174 pubkey_auth_info(authctxt, key, NULL);
176 /* test for correct signature */
178 if (PRIVSEP(user_key_allowed(authctxt->pw, key, 1)) &&
179 PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
180 buffer_len(&b))) == 1) {
182 /* Record the successful key to prevent reuse */
183 auth2_record_userkey(authctxt, key);
184 key = NULL; /* Don't free below */
189 debug("%s: test whether pkalg/pkblob are acceptable for %s %s",
190 __func__, sshkey_type(key), fp);
193 /* XXX fake reply and always send PK_OK ? */
195 * XXX this allows testing whether a user is allowed
196 * to login: if you happen to have a valid pubkey this
197 * message is sent. the message is NEVER sent at all
198 * if a user is not allowed to login. is this an
201 if (PRIVSEP(user_key_allowed(authctxt->pw, key, 0))) {
202 packet_start(SSH2_MSG_USERAUTH_PK_OK);
203 packet_put_string(pkalg, alen);
204 packet_put_string(pkblob, blen);
207 authctxt->postponed = 1;
210 if (authenticated != 1)
211 auth_clear_options();
213 debug2("%s: authenticated %d pkalg %s", __func__, authenticated, pkalg);
219 return authenticated;
223 pubkey_auth_info(Authctxt *authctxt, const Key *key, const char *fmt, ...)
232 i = vasprintf(&extra, fmt, ap);
234 if (i < 0 || extra == NULL)
235 fatal("%s: vasprintf failed", __func__);
238 if (key_is_cert(key)) {
239 fp = sshkey_fingerprint(key->cert->signature_key,
240 options.fingerprint_hash, SSH_FP_DEFAULT);
241 auth_info(authctxt, "%s ID %s (serial %llu) CA %s %s%s%s",
242 key_type(key), key->cert->key_id,
243 (unsigned long long)key->cert->serial,
244 key_type(key->cert->signature_key),
245 fp == NULL ? "(null)" : fp,
246 extra == NULL ? "" : ", ", extra == NULL ? "" : extra);
249 fp = sshkey_fingerprint(key, options.fingerprint_hash,
251 auth_info(authctxt, "%s %s%s%s", key_type(key),
252 fp == NULL ? "(null)" : fp,
253 extra == NULL ? "" : ", ", extra == NULL ? "" : extra);
260 * Splits 's' into an argument vector. Handles quoted string and basic
261 * escape characters (\\, \", \'). Caller must free the argument vector
265 split_argv(const char *s, int *argcp, char ***argvp)
267 int r = SSH_ERR_INTERNAL_ERROR;
268 int argc = 0, quote, i, j;
269 char *arg, **argv = xcalloc(1, sizeof(*argv));
274 for (i = 0; s[i] != '\0'; i++) {
275 /* Skip leading whitespace */
276 if (s[i] == ' ' || s[i] == '\t')
279 /* Start of a token */
282 (s[i + 1] == '\'' || s[i + 1] == '\"' || s[i + 1] == '\\'))
284 else if (s[i] == '\'' || s[i] == '"')
287 argv = xreallocarray(argv, (argc + 2), sizeof(*argv));
288 arg = argv[argc++] = xcalloc(1, strlen(s + i) + 1);
291 /* Copy the token in, removing escapes */
292 for (j = 0; s[i] != '\0'; i++) {
294 if (s[i + 1] == '\'' ||
300 /* Unrecognised escape */
303 } else if (quote == 0 && (s[i] == ' ' || s[i] == '\t'))
305 else if (quote != 0 && s[i] == quote)
312 /* Ran out of string looking for close quote */
313 r = SSH_ERR_INVALID_FORMAT;
326 if (argc != 0 && argv != NULL) {
327 for (i = 0; i < argc; i++)
335 * Reassemble an argument vector into a string, quoting and escaping as
336 * necessary. Caller must free returned string.
339 assemble_argv(int argc, char **argv)
343 struct sshbuf *buf, *arg;
345 if ((buf = sshbuf_new()) == NULL || (arg = sshbuf_new()) == NULL)
346 fatal("%s: sshbuf_new failed", __func__);
348 for (i = 0; i < argc; i++) {
351 for (j = 0; argv[i][j] != '\0'; j++) {
358 r = sshbuf_put_u8(arg, c);
363 if ((r = sshbuf_put_u8(arg, '\\')) != 0)
367 r = sshbuf_put_u8(arg, c);
371 fatal("%s: sshbuf_put_u8: %s",
372 __func__, ssh_err(r));
374 if ((i != 0 && (r = sshbuf_put_u8(buf, ' ')) != 0) ||
375 (ws != 0 && (r = sshbuf_put_u8(buf, '"')) != 0) ||
376 (r = sshbuf_putb(buf, arg)) != 0 ||
377 (ws != 0 && (r = sshbuf_put_u8(buf, '"')) != 0))
378 fatal("%s: buffer error: %s", __func__, ssh_err(r));
380 if ((ret = malloc(sshbuf_len(buf) + 1)) == NULL)
381 fatal("%s: malloc failed", __func__);
382 memcpy(ret, sshbuf_ptr(buf), sshbuf_len(buf));
383 ret[sshbuf_len(buf)] = '\0';
390 * Runs command in a subprocess. Returns pid on success and a FILE* to the
391 * subprocess' stdout or 0 on failure.
392 * NB. "command" is only used for logging.
395 subprocess(const char *tag, struct passwd *pw, const char *command,
396 int ac, char **av, FILE **child)
400 int devnull, p[2], i;
402 char *cp, errmsg[512];
408 debug3("%s: %s command \"%s\" running as %s", __func__,
409 tag, command, pw->pw_name);
411 /* Verify the path exists and is safe-ish to execute */
413 error("%s path is not absolute", tag);
416 temporarily_use_uid(pw);
417 if (stat(av[0], &st) < 0) {
418 error("Could not stat %s \"%s\": %s", tag,
419 av[0], strerror(errno));
423 if (auth_secure_path(av[0], &st, NULL, 0,
424 errmsg, sizeof(errmsg)) != 0) {
425 error("Unsafe %s \"%s\": %s", tag, av[0], errmsg);
431 * Run the command; stderr is left in place, stdout is the
432 * authorized_keys output.
435 error("%s: pipe: %s", tag, strerror(errno));
441 * Don't want to call this in the child, where it can fatal() and
442 * run cleanup_exit() code.
446 switch ((pid = fork())) {
448 error("%s: fork: %s", tag, strerror(errno));
453 /* Prepare a minimal environment for the child. */
455 child_env = xcalloc(sizeof(*child_env), envsize);
456 child_set_env(&child_env, &envsize, "PATH", _PATH_STDPATH);
457 child_set_env(&child_env, &envsize, "USER", pw->pw_name);
458 child_set_env(&child_env, &envsize, "LOGNAME", pw->pw_name);
459 child_set_env(&child_env, &envsize, "HOME", pw->pw_dir);
460 if ((cp = getenv("LANG")) != NULL)
461 child_set_env(&child_env, &envsize, "LANG", cp);
463 for (i = 0; i < NSIG; i++)
466 if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
467 error("%s: open %s: %s", tag, _PATH_DEVNULL,
471 /* Keep stderr around a while longer to catch errors */
472 if (dup2(devnull, STDIN_FILENO) == -1 ||
473 dup2(p[1], STDOUT_FILENO) == -1) {
474 error("%s: dup2: %s", tag, strerror(errno));
477 closefrom(STDERR_FILENO + 1);
479 /* Don't use permanently_set_uid() here to avoid fatal() */
480 if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) != 0) {
481 error("%s: setresgid %u: %s", tag, (u_int)pw->pw_gid,
485 if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) != 0) {
486 error("%s: setresuid %u: %s", tag, (u_int)pw->pw_uid,
490 /* stdin is pointed to /dev/null at this point */
491 if (dup2(STDIN_FILENO, STDERR_FILENO) == -1) {
492 error("%s: dup2: %s", tag, strerror(errno));
496 execve(av[0], av, child_env);
497 error("%s exec \"%s\": %s", tag, command, strerror(errno));
499 default: /* parent */
504 if ((f = fdopen(p[0], "r")) == NULL) {
505 error("%s: fdopen: %s", tag, strerror(errno));
507 /* Don't leave zombie child */
509 while (waitpid(pid, NULL, 0) == -1 && errno == EINTR)
514 debug3("%s: %s pid %ld", __func__, tag, (long)pid);
519 /* Returns 0 if pid exited cleanly, non-zero otherwise */
521 exited_cleanly(pid_t pid, const char *tag, const char *cmd)
525 while (waitpid(pid, &status, 0) == -1) {
526 if (errno != EINTR) {
527 error("%s: waitpid: %s", tag, strerror(errno));
531 if (WIFSIGNALED(status)) {
532 error("%s %s exited on signal %d", tag, cmd, WTERMSIG(status));
534 } else if (WEXITSTATUS(status) != 0) {
535 error("%s %s failed, status %d", tag, cmd, WEXITSTATUS(status));
542 match_principals_option(const char *principal_list, struct sshkey_cert *cert)
547 /* XXX percent_expand() sequences for authorized_principals? */
549 for (i = 0; i < cert->nprincipals; i++) {
550 if ((result = match_list(cert->principals[i],
551 principal_list, NULL)) != NULL) {
552 debug3("matched principal from key options \"%.100s\"",
562 process_principals(FILE *f, char *file, struct passwd *pw,
563 const struct sshkey_cert *cert)
565 char line[SSH_MAX_PUBKEY_BYTES], *cp, *ep, *line_opts;
569 while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
570 /* Skip leading whitespace. */
571 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
573 /* Skip blank and comment lines. */
574 if ((ep = strchr(cp, '#')) != NULL)
576 if (!*cp || *cp == '\n')
578 /* Trim trailing whitespace. */
579 ep = cp + strlen(cp) - 1;
580 while (ep > cp && (*ep == '\n' || *ep == ' ' || *ep == '\t'))
583 * If the line has internal whitespace then assume it has
587 if ((ep = strrchr(cp, ' ')) != NULL ||
588 (ep = strrchr(cp, '\t')) != NULL) {
589 for (; *ep == ' ' || *ep == '\t'; ep++)
594 for (i = 0; i < cert->nprincipals; i++) {
595 if (strcmp(cp, cert->principals[i]) == 0) {
596 debug3("%s:%lu: matched principal \"%.100s\"",
597 file == NULL ? "(command)" : file,
598 linenum, cert->principals[i]);
599 if (auth_parse_options(pw, line_opts,
610 match_principals_file(char *file, struct passwd *pw, struct sshkey_cert *cert)
615 temporarily_use_uid(pw);
616 debug("trying authorized principals file %s", file);
617 if ((f = auth_openprincipals(file, pw, options.strict_modes)) == NULL) {
621 success = process_principals(f, file, pw, cert);
628 * Checks whether principal is allowed in output of command.
629 * returns 1 if the principal is allowed or 0 otherwise.
632 match_principals_command(struct passwd *user_pw, const struct sshkey *key)
634 const struct sshkey_cert *cert = key->cert;
636 int r, ok, found_principal = 0;
638 int i, ac = 0, uid_swapped = 0;
640 char *tmp, *username = NULL, *command = NULL, **av = NULL;
641 char *ca_fp = NULL, *key_fp = NULL, *catext = NULL, *keytext = NULL;
643 void (*osigchld)(int);
645 if (options.authorized_principals_command == NULL)
647 if (options.authorized_principals_command_user == NULL) {
648 error("No user for AuthorizedPrincipalsCommand specified, "
654 * NB. all returns later this function should go via "out" to
655 * ensure the original SIGCHLD handler is restored properly.
657 osigchld = signal(SIGCHLD, SIG_DFL);
659 /* Prepare and verify the user for the command */
660 username = percent_expand(options.authorized_principals_command_user,
661 "u", user_pw->pw_name, (char *)NULL);
662 pw = getpwnam(username);
664 error("AuthorizedPrincipalsCommandUser \"%s\" not found: %s",
665 username, strerror(errno));
669 /* Turn the command into an argument vector */
670 if (split_argv(options.authorized_principals_command, &ac, &av) != 0) {
671 error("AuthorizedPrincipalsCommand \"%s\" contains "
672 "invalid quotes", command);
676 error("AuthorizedPrincipalsCommand \"%s\" yielded no arguments",
680 if ((ca_fp = sshkey_fingerprint(cert->signature_key,
681 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
682 error("%s: sshkey_fingerprint failed", __func__);
685 if ((key_fp = sshkey_fingerprint(key,
686 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
687 error("%s: sshkey_fingerprint failed", __func__);
690 if ((r = sshkey_to_base64(cert->signature_key, &catext)) != 0) {
691 error("%s: sshkey_to_base64 failed: %s", __func__, ssh_err(r));
694 if ((r = sshkey_to_base64(key, &keytext)) != 0) {
695 error("%s: sshkey_to_base64 failed: %s", __func__, ssh_err(r));
698 snprintf(serial_s, sizeof(serial_s), "%llu",
699 (unsigned long long)cert->serial);
700 for (i = 1; i < ac; i++) {
701 tmp = percent_expand(av[i],
702 "u", user_pw->pw_name,
703 "h", user_pw->pw_dir,
704 "t", sshkey_ssh_name(key),
705 "T", sshkey_ssh_name(cert->signature_key),
714 fatal("%s: percent_expand failed", __func__);
718 /* Prepare a printable command for logs, etc. */
719 command = assemble_argv(ac, av);
721 if ((pid = subprocess("AuthorizedPrincipalsCommand", pw, command,
726 temporarily_use_uid(pw);
728 ok = process_principals(f, NULL, pw, cert);
730 if (exited_cleanly(pid, "AuthorizedPrincipalsCommand", command) != 0)
733 /* Read completed successfully */
734 found_principal = ok;
738 signal(SIGCHLD, osigchld);
739 for (i = 0; i < ac; i++)
750 return found_principal;
753 * Checks whether key is allowed in authorized_keys-format file,
754 * returns 1 if the key is allowed or 0 otherwise.
757 check_authkeys_file(FILE *f, char *file, Key* key, struct passwd *pw)
759 char line[SSH_MAX_PUBKEY_BYTES];
767 while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) {
768 char *cp, *key_options = NULL, *fp = NULL;
769 const char *reason = NULL;
773 found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
774 auth_clear_options();
776 /* Skip leading whitespace, empty and comment lines. */
777 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
779 if (!*cp || *cp == '\n' || *cp == '#')
782 if (key_read(found, &cp) != 1) {
783 /* no key? check if there are options for this key */
785 debug2("user_key_allowed: check options: '%s'", cp);
787 for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
788 if (*cp == '\\' && cp[1] == '"')
789 cp++; /* Skip both */
793 /* Skip remaining whitespace. */
794 for (; *cp == ' ' || *cp == '\t'; cp++)
796 if (key_read(found, &cp) != 1) {
797 debug2("user_key_allowed: advance: '%s'", cp);
798 /* still no key? advance to next line*/
802 if (key_is_cert(key)) {
803 if (!key_equal(found, key->cert->signature_key))
805 if (auth_parse_options(pw, key_options, file,
808 if (!key_is_cert_authority)
810 if ((fp = sshkey_fingerprint(found,
811 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
813 debug("matching CA found: file %s, line %lu, %s %s",
814 file, linenum, key_type(found), fp);
816 * If the user has specified a list of principals as
817 * a key option, then prefer that list to matching
818 * their username in the certificate principals list.
820 if (authorized_principals != NULL &&
821 !match_principals_option(authorized_principals,
823 reason = "Certificate does not contain an "
824 "authorized principal";
828 auth_debug_add("%s", reason);
831 if (key_cert_check_authority(key, 0, 0,
832 authorized_principals == NULL ? pw->pw_name : NULL,
835 if (auth_cert_options(key, pw, &reason) != 0)
837 verbose("Accepted certificate ID \"%s\" (serial %llu) "
838 "signed by %s CA %s via %s", key->cert->key_id,
839 (unsigned long long)key->cert->serial,
840 key_type(found), fp, file);
844 } else if (key_equal(found, key)) {
845 if (auth_parse_options(pw, key_options, file,
848 if (key_is_cert_authority)
850 if ((fp = sshkey_fingerprint(found,
851 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
853 debug("matching key found: file %s, line %lu %s %s",
854 file, linenum, key_type(found), fp);
863 debug2("key not found");
867 /* Authenticate a certificate key against TrustedUserCAKeys */
869 user_cert_trusted_ca(struct passwd *pw, Key *key)
871 char *ca_fp, *principals_file = NULL;
873 int ret = 0, found_principal = 0, use_authorized_principals;
875 if (!key_is_cert(key) || options.trusted_user_ca_keys == NULL)
878 if ((ca_fp = sshkey_fingerprint(key->cert->signature_key,
879 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
882 if (sshkey_in_file(key->cert->signature_key,
883 options.trusted_user_ca_keys, 1, 0) != 0) {
884 debug2("%s: CA %s %s is not listed in %s", __func__,
885 key_type(key->cert->signature_key), ca_fp,
886 options.trusted_user_ca_keys);
890 * If AuthorizedPrincipals is in use, then compare the certificate
891 * principals against the names in that file rather than matching
892 * against the username.
894 if ((principals_file = authorized_principals_file(pw)) != NULL) {
895 if (match_principals_file(principals_file, pw, key->cert))
898 /* Try querying command if specified */
899 if (!found_principal && match_principals_command(pw, key))
901 /* If principals file or command is specified, then require a match */
902 use_authorized_principals = principals_file != NULL ||
903 options.authorized_principals_command != NULL;
904 if (!found_principal && use_authorized_principals) {
905 reason = "Certificate does not contain an authorized principal";
908 auth_debug_add("%s", reason);
911 if (key_cert_check_authority(key, 0, 1,
912 use_authorized_principals ? NULL : pw->pw_name, &reason) != 0)
914 if (auth_cert_options(key, pw, &reason) != 0)
917 verbose("Accepted certificate ID \"%s\" (serial %llu) signed by "
918 "%s CA %s via %s", key->cert->key_id,
919 (unsigned long long)key->cert->serial,
920 key_type(key->cert->signature_key), ca_fp,
921 options.trusted_user_ca_keys);
925 free(principals_file);
931 * Checks whether key is allowed in file.
932 * returns 1 if the key is allowed or 0 otherwise.
935 user_key_allowed2(struct passwd *pw, Key *key, char *file)
940 /* Temporarily use the user's uid. */
941 temporarily_use_uid(pw);
943 debug("trying public key file %s", file);
944 if ((f = auth_openkeyfile(file, pw, options.strict_modes)) != NULL) {
945 found_key = check_authkeys_file(f, file, key, pw);
954 * Checks whether key is allowed in output of command.
955 * returns 1 if the key is allowed or 0 otherwise.
958 user_key_command_allowed2(struct passwd *user_pw, Key *key)
961 int r, ok, found_key = 0;
963 int i, uid_swapped = 0, ac = 0;
965 char *username = NULL, *key_fp = NULL, *keytext = NULL;
966 char *tmp, *command = NULL, **av = NULL;
967 void (*osigchld)(int);
969 if (options.authorized_keys_command == NULL)
971 if (options.authorized_keys_command_user == NULL) {
972 error("No user for AuthorizedKeysCommand specified, skipping");
977 * NB. all returns later this function should go via "out" to
978 * ensure the original SIGCHLD handler is restored properly.
980 osigchld = signal(SIGCHLD, SIG_DFL);
982 /* Prepare and verify the user for the command */
983 username = percent_expand(options.authorized_keys_command_user,
984 "u", user_pw->pw_name, (char *)NULL);
985 pw = getpwnam(username);
987 error("AuthorizedKeysCommandUser \"%s\" not found: %s",
988 username, strerror(errno));
992 /* Prepare AuthorizedKeysCommand */
993 if ((key_fp = sshkey_fingerprint(key, options.fingerprint_hash,
994 SSH_FP_DEFAULT)) == NULL) {
995 error("%s: sshkey_fingerprint failed", __func__);
998 if ((r = sshkey_to_base64(key, &keytext)) != 0) {
999 error("%s: sshkey_to_base64 failed: %s", __func__, ssh_err(r));
1003 /* Turn the command into an argument vector */
1004 if (split_argv(options.authorized_keys_command, &ac, &av) != 0) {
1005 error("AuthorizedKeysCommand \"%s\" contains invalid quotes",
1010 error("AuthorizedKeysCommand \"%s\" yielded no arguments",
1014 for (i = 1; i < ac; i++) {
1015 tmp = percent_expand(av[i],
1016 "u", user_pw->pw_name,
1017 "h", user_pw->pw_dir,
1018 "t", sshkey_ssh_name(key),
1023 fatal("%s: percent_expand failed", __func__);
1027 /* Prepare a printable command for logs, etc. */
1028 command = assemble_argv(ac, av);
1031 * If AuthorizedKeysCommand was run without arguments
1032 * then fall back to the old behaviour of passing the
1033 * target username as a single argument.
1036 av = xreallocarray(av, ac + 2, sizeof(*av));
1037 av[1] = xstrdup(user_pw->pw_name);
1039 /* Fix up command too, since it is used in log messages */
1041 xasprintf(&command, "%s %s", av[0], av[1]);
1044 if ((pid = subprocess("AuthorizedKeysCommand", pw, command,
1049 temporarily_use_uid(pw);
1051 ok = check_authkeys_file(f, options.authorized_keys_command, key, pw);
1053 if (exited_cleanly(pid, "AuthorizedKeysCommand", command) != 0)
1056 /* Read completed successfully */
1061 signal(SIGCHLD, osigchld);
1062 for (i = 0; i < ac; i++)
1075 * Check whether key authenticates and authorises the user.
1078 user_key_allowed(struct passwd *pw, Key *key, int auth_attempt)
1083 if (auth_key_is_revoked(key))
1085 if (key_is_cert(key) && auth_key_is_revoked(key->cert->signature_key))
1088 success = user_cert_trusted_ca(pw, key);
1092 success = user_key_command_allowed2(pw, key);
1096 for (i = 0; !success && i < options.num_authkeys_files; i++) {
1098 if (strcasecmp(options.authorized_keys_files[i], "none") == 0)
1100 file = expand_authorized_keys(
1101 options.authorized_keys_files[i], pw);
1103 success = user_key_allowed2(pw, key, file);
1110 /* Records a public key in the list of previously-successful keys */
1112 auth2_record_userkey(Authctxt *authctxt, struct sshkey *key)
1114 struct sshkey **tmp;
1116 if (authctxt->nprev_userkeys >= INT_MAX ||
1117 (tmp = reallocarray(authctxt->prev_userkeys,
1118 authctxt->nprev_userkeys + 1, sizeof(*tmp))) == NULL)
1119 fatal("%s: reallocarray failed", __func__);
1120 authctxt->prev_userkeys = tmp;
1121 authctxt->prev_userkeys[authctxt->nprev_userkeys] = key;
1122 authctxt->nprev_userkeys++;
1125 /* Checks whether a key has already been used successfully for authentication */
1127 auth2_userkey_already_used(Authctxt *authctxt, struct sshkey *key)
1131 for (i = 0; i < authctxt->nprev_userkeys; i++) {
1132 if (sshkey_equal_public(key, authctxt->prev_userkeys[i])) {
1139 Authmethod method_pubkey = {
1142 &options.pubkey_authentication