| /* $OpenBSD: auth.c,v 1.70 2006/07/11 20:07:25 stevesk Exp $ */ |
| /* |
| * Copyright (c) 2000 Markus Friedl. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #include "includes.h" |
| |
| #include <sys/types.h> |
| #include <sys/stat.h> |
| |
| #include <errno.h> |
| #ifdef HAVE_PATHS_H |
| # include <paths.h> |
| #endif |
| #include <pwd.h> |
| #ifdef HAVE_LOGIN_H |
| #include <login.h> |
| #endif |
| #ifdef USE_SHADOW |
| #include <shadow.h> |
| #endif |
| #ifdef HAVE_LIBGEN_H |
| #include <libgen.h> |
| #endif |
| #include <stdarg.h> |
| |
| #include "xmalloc.h" |
| #include "match.h" |
| #include "groupaccess.h" |
| #include "log.h" |
| #include "servconf.h" |
| #include "auth.h" |
| #include "auth-options.h" |
| #include "canohost.h" |
| #include "buffer.h" |
| #include "bufaux.h" |
| #include "uidswap.h" |
| #include "misc.h" |
| #include "bufaux.h" |
| #include "packet.h" |
| #include "loginrec.h" |
| #include "monitor_wrap.h" |
| |
| /* import */ |
| extern ServerOptions options; |
| extern int use_privsep; |
| extern Buffer loginmsg; |
| |
| /* Debugging messages */ |
| Buffer auth_debug; |
| int auth_debug_init; |
| |
| /* |
| * Check if the user is allowed to log in via ssh. If user is listed |
| * in DenyUsers or one of user's groups is listed in DenyGroups, false |
| * will be returned. If AllowUsers isn't empty and user isn't listed |
| * there, or if AllowGroups isn't empty and one of user's groups isn't |
| * listed there, false will be returned. |
| * If the user's shell is not executable, false will be returned. |
| * Otherwise true is returned. |
| */ |
| int |
| allowed_user(struct passwd * pw) |
| { |
| struct stat st; |
| const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL; |
| char *shell; |
| u_int i; |
| #ifdef USE_SHADOW |
| struct spwd *spw = NULL; |
| #endif |
| |
| /* Shouldn't be called if pw is NULL, but better safe than sorry... */ |
| if (!pw || !pw->pw_name) |
| return 0; |
| |
| #ifdef USE_SHADOW |
| if (!options.use_pam) |
| spw = getspnam(pw->pw_name); |
| #ifdef HAS_SHADOW_EXPIRE |
| if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw)) |
| return 0; |
| #endif /* HAS_SHADOW_EXPIRE */ |
| #endif /* USE_SHADOW */ |
| |
| /* grab passwd field for locked account check */ |
| #ifdef USE_SHADOW |
| if (spw != NULL) |
| #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF) |
| passwd = get_iaf_password(pw); |
| #else |
| passwd = spw->sp_pwdp; |
| #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */ |
| #else |
| passwd = pw->pw_passwd; |
| #endif |
| |
| /* check for locked account */ |
| if (!options.use_pam && passwd && *passwd) { |
| int locked = 0; |
| |
| #ifdef LOCKED_PASSWD_STRING |
| if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0) |
| locked = 1; |
| #endif |
| #ifdef LOCKED_PASSWD_PREFIX |
| if (strncmp(passwd, LOCKED_PASSWD_PREFIX, |
| strlen(LOCKED_PASSWD_PREFIX)) == 0) |
| locked = 1; |
| #endif |
| #ifdef LOCKED_PASSWD_SUBSTR |
| if (strstr(passwd, LOCKED_PASSWD_SUBSTR)) |
| locked = 1; |
| #endif |
| #if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF) |
| free(passwd); |
| #endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */ |
| if (locked) { |
| logit("User %.100s not allowed because account is locked", |
| pw->pw_name); |
| return 0; |
| } |
| } |
| |
| /* |
| * Get the shell from the password data. An empty shell field is |
| * legal, and means /bin/sh. |
| */ |
| shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell; |
| |
| /* deny if shell does not exists or is not executable */ |
| if (stat(shell, &st) != 0) { |
| logit("User %.100s not allowed because shell %.100s does not exist", |
| pw->pw_name, shell); |
| return 0; |
| } |
| if (S_ISREG(st.st_mode) == 0 || |
| (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) { |
| logit("User %.100s not allowed because shell %.100s is not executable", |
| pw->pw_name, shell); |
| return 0; |
| } |
| |
| if (options.num_deny_users > 0 || options.num_allow_users > 0 || |
| options.num_deny_groups > 0 || options.num_allow_groups > 0) { |
| hostname = get_canonical_hostname(options.use_dns); |
| ipaddr = get_remote_ipaddr(); |
| } |
| |
| /* Return false if user is listed in DenyUsers */ |
| if (options.num_deny_users > 0) { |
| for (i = 0; i < options.num_deny_users; i++) |
| if (match_user(pw->pw_name, hostname, ipaddr, |
| options.deny_users[i])) { |
| logit("User %.100s from %.100s not allowed " |
| "because listed in DenyUsers", |
| pw->pw_name, hostname); |
| return 0; |
| } |
| } |
| /* Return false if AllowUsers isn't empty and user isn't listed there */ |
| if (options.num_allow_users > 0) { |
| for (i = 0; i < options.num_allow_users; i++) |
| if (match_user(pw->pw_name, hostname, ipaddr, |
| options.allow_users[i])) |
| break; |
| /* i < options.num_allow_users iff we break for loop */ |
| if (i >= options.num_allow_users) { |
| logit("User %.100s from %.100s not allowed because " |
| "not listed in AllowUsers", pw->pw_name, hostname); |
| return 0; |
| } |
| } |
| if (options.num_deny_groups > 0 || options.num_allow_groups > 0) { |
| /* Get the user's group access list (primary and supplementary) */ |
| if (ga_init(pw->pw_name, pw->pw_gid) == 0) { |
| logit("User %.100s from %.100s not allowed because " |
| "not in any group", pw->pw_name, hostname); |
| return 0; |
| } |
| |
| /* Return false if one of user's groups is listed in DenyGroups */ |
| if (options.num_deny_groups > 0) |
| if (ga_match(options.deny_groups, |
| options.num_deny_groups)) { |
| ga_free(); |
| logit("User %.100s from %.100s not allowed " |
| "because a group is listed in DenyGroups", |
| pw->pw_name, hostname); |
| return 0; |
| } |
| /* |
| * Return false if AllowGroups isn't empty and one of user's groups |
| * isn't listed there |
| */ |
| if (options.num_allow_groups > 0) |
| if (!ga_match(options.allow_groups, |
| options.num_allow_groups)) { |
| ga_free(); |
| logit("User %.100s from %.100s not allowed " |
| "because none of user's groups are listed " |
| "in AllowGroups", pw->pw_name, hostname); |
| return 0; |
| } |
| ga_free(); |
| } |
| |
| #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER |
| if (!sys_auth_allowed_user(pw, &loginmsg)) |
| return 0; |
| #endif |
| |
| /* We found no reason not to let this user try to log on... */ |
| return 1; |
| } |
| |
| void |
| auth_log(Authctxt *authctxt, int authenticated, char *method, char *info) |
| { |
| void (*authlog) (const char *fmt,...) = verbose; |
| char *authmsg; |
| |
| if (use_privsep && !mm_is_monitor() && !authctxt->postponed) |
| return; |
| |
| /* Raise logging level */ |
| if (authenticated == 1 || |
| !authctxt->valid || |
| authctxt->failures >= options.max_authtries / 2 || |
| strcmp(method, "password") == 0) |
| authlog = logit; |
| |
| if (authctxt->postponed) |
| authmsg = "Postponed"; |
| else |
| authmsg = authenticated ? "Accepted" : "Failed"; |
| |
| authlog("%s %s for %s%.100s from %.200s port %d%s", |
| authmsg, |
| method, |
| authctxt->valid ? "" : "invalid user ", |
| authctxt->user, |
| get_remote_ipaddr(), |
| get_remote_port(), |
| info); |
| |
| #ifdef CUSTOM_FAILED_LOGIN |
| if (authenticated == 0 && !authctxt->postponed && |
| (strcmp(method, "password") == 0 || |
| strncmp(method, "keyboard-interactive", 20) == 0 || |
| strcmp(method, "challenge-response") == 0)) |
| record_failed_login(authctxt->user, |
| get_canonical_hostname(options.use_dns), "ssh"); |
| #endif |
| #ifdef SSH_AUDIT_EVENTS |
| if (authenticated == 0 && !authctxt->postponed) |
| audit_event(audit_classify_auth(method)); |
| #endif |
| } |
| |
| /* |
| * Check whether root logins are disallowed. |
| */ |
| int |
| auth_root_allowed(char *method) |
| { |
| switch (options.permit_root_login) { |
| case PERMIT_YES: |
| return 1; |
| case PERMIT_NO_PASSWD: |
| if (strcmp(method, "password") != 0) |
| return 1; |
| break; |
| case PERMIT_FORCED_ONLY: |
| if (forced_command) { |
| logit("Root login accepted for forced command."); |
| return 1; |
| } |
| break; |
| } |
| logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr()); |
| return 0; |
| } |
| |
| |
| /* |
| * Given a template and a passwd structure, build a filename |
| * by substituting % tokenised options. Currently, %% becomes '%', |
| * %h becomes the home directory and %u the username. |
| * |
| * This returns a buffer allocated by xmalloc. |
| */ |
| static char * |
| expand_authorized_keys(const char *filename, struct passwd *pw) |
| { |
| char *file, ret[MAXPATHLEN]; |
| int i; |
| |
| file = percent_expand(filename, "h", pw->pw_dir, |
| "u", pw->pw_name, (char *)NULL); |
| |
| /* |
| * Ensure that filename starts anchored. If not, be backward |
| * compatible and prepend the '%h/' |
| */ |
| if (*file == '/') |
| return (file); |
| |
| i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file); |
| if (i < 0 || (size_t)i >= sizeof(ret)) |
| fatal("expand_authorized_keys: path too long"); |
| xfree(file); |
| return (xstrdup(ret)); |
| } |
| |
| char * |
| authorized_keys_file(struct passwd *pw) |
| { |
| return expand_authorized_keys(options.authorized_keys_file, pw); |
| } |
| |
| char * |
| authorized_keys_file2(struct passwd *pw) |
| { |
| return expand_authorized_keys(options.authorized_keys_file2, pw); |
| } |
| |
| /* return ok if key exists in sysfile or userfile */ |
| HostStatus |
| check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host, |
| const char *sysfile, const char *userfile) |
| { |
| Key *found; |
| char *user_hostfile; |
| struct stat st; |
| HostStatus host_status; |
| |
| /* Check if we know the host and its host key. */ |
| found = key_new(key->type); |
| host_status = check_host_in_hostfile(sysfile, host, key, found, NULL); |
| |
| if (host_status != HOST_OK && userfile != NULL) { |
| user_hostfile = tilde_expand_filename(userfile, pw->pw_uid); |
| if (options.strict_modes && |
| (stat(user_hostfile, &st) == 0) && |
| ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || |
| (st.st_mode & 022) != 0)) { |
| logit("Authentication refused for %.100s: " |
| "bad owner or modes for %.200s", |
| pw->pw_name, user_hostfile); |
| } else { |
| temporarily_use_uid(pw); |
| host_status = check_host_in_hostfile(user_hostfile, |
| host, key, found, NULL); |
| restore_uid(); |
| } |
| xfree(user_hostfile); |
| } |
| key_free(found); |
| |
| debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ? |
| "ok" : "not found", host); |
| return host_status; |
| } |
| |
| |
| /* |
| * Check a given file for security. This is defined as all components |
| * of the path to the file must be owned by either the owner of |
| * of the file or root and no directories must be group or world writable. |
| * |
| * XXX Should any specific check be done for sym links ? |
| * |
| * Takes an open file descriptor, the file name, a uid and and |
| * error buffer plus max size as arguments. |
| * |
| * Returns 0 on success and -1 on failure |
| */ |
| int |
| secure_filename(FILE *f, const char *file, struct passwd *pw, |
| char *err, size_t errlen) |
| { |
| uid_t uid = pw->pw_uid; |
| char buf[MAXPATHLEN], homedir[MAXPATHLEN]; |
| char *cp; |
| int comparehome = 0; |
| struct stat st; |
| |
| if (realpath(file, buf) == NULL) { |
| snprintf(err, errlen, "realpath %s failed: %s", file, |
| strerror(errno)); |
| return -1; |
| } |
| if (realpath(pw->pw_dir, homedir) != NULL) |
| comparehome = 1; |
| |
| /* check the open file to avoid races */ |
| if (fstat(fileno(f), &st) < 0 || |
| (st.st_uid != 0 && st.st_uid != uid) || |
| (st.st_mode & 022) != 0) { |
| snprintf(err, errlen, "bad ownership or modes for file %s", |
| buf); |
| return -1; |
| } |
| |
| /* for each component of the canonical path, walking upwards */ |
| for (;;) { |
| if ((cp = dirname(buf)) == NULL) { |
| snprintf(err, errlen, "dirname() failed"); |
| return -1; |
| } |
| strlcpy(buf, cp, sizeof(buf)); |
| |
| debug3("secure_filename: checking '%s'", buf); |
| if (stat(buf, &st) < 0 || |
| (st.st_uid != 0 && st.st_uid != uid) || |
| (st.st_mode & 022) != 0) { |
| snprintf(err, errlen, |
| "bad ownership or modes for directory %s", buf); |
| return -1; |
| } |
| |
| /* If are passed the homedir then we can stop */ |
| if (comparehome && strcmp(homedir, buf) == 0) { |
| debug3("secure_filename: terminating check at '%s'", |
| buf); |
| break; |
| } |
| /* |
| * dirname should always complete with a "/" path, |
| * but we can be paranoid and check for "." too |
| */ |
| if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0)) |
| break; |
| } |
| return 0; |
| } |
| |
| struct passwd * |
| getpwnamallow(const char *user) |
| { |
| #ifdef HAVE_LOGIN_CAP |
| extern login_cap_t *lc; |
| #ifdef BSD_AUTH |
| auth_session_t *as; |
| #endif |
| #endif |
| struct passwd *pw; |
| |
| pw = getpwnam(user); |
| if (pw == NULL) { |
| logit("Invalid user %.100s from %.100s", |
| user, get_remote_ipaddr()); |
| #ifdef CUSTOM_FAILED_LOGIN |
| record_failed_login(user, |
| get_canonical_hostname(options.use_dns), "ssh"); |
| #endif |
| #ifdef SSH_AUDIT_EVENTS |
| audit_event(SSH_INVALID_USER); |
| #endif /* SSH_AUDIT_EVENTS */ |
| return (NULL); |
| } |
| if (!allowed_user(pw)) |
| return (NULL); |
| #ifdef HAVE_LOGIN_CAP |
| if ((lc = login_getclass(pw->pw_class)) == NULL) { |
| debug("unable to get login class: %s", user); |
| return (NULL); |
| } |
| #ifdef BSD_AUTH |
| if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 || |
| auth_approval(as, lc, pw->pw_name, "ssh") <= 0) { |
| debug("Approval failure for %s", user); |
| pw = NULL; |
| } |
| if (as != NULL) |
| auth_close(as); |
| #endif |
| #endif |
| if (pw != NULL) |
| return (pwcopy(pw)); |
| return (NULL); |
| } |
| |
| void |
| auth_debug_add(const char *fmt,...) |
| { |
| char buf[1024]; |
| va_list args; |
| |
| if (!auth_debug_init) |
| return; |
| |
| va_start(args, fmt); |
| vsnprintf(buf, sizeof(buf), fmt, args); |
| va_end(args); |
| buffer_put_cstring(&auth_debug, buf); |
| } |
| |
| void |
| auth_debug_send(void) |
| { |
| char *msg; |
| |
| if (!auth_debug_init) |
| return; |
| while (buffer_len(&auth_debug)) { |
| msg = buffer_get_string(&auth_debug, NULL); |
| packet_send_debug("%s", msg); |
| xfree(msg); |
| } |
| } |
| |
| void |
| auth_debug_reset(void) |
| { |
| if (auth_debug_init) |
| buffer_clear(&auth_debug); |
| else { |
| buffer_init(&auth_debug); |
| auth_debug_init = 1; |
| } |
| } |
| |
| struct passwd * |
| fakepw(void) |
| { |
| static struct passwd fake; |
| |
| memset(&fake, 0, sizeof(fake)); |
| fake.pw_name = "NOUSER"; |
| fake.pw_passwd = |
| "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK"; |
| fake.pw_gecos = "NOUSER"; |
| fake.pw_uid = (uid_t)-1; |
| fake.pw_gid = (gid_t)-1; |
| #ifdef HAVE_PW_CLASS_IN_PASSWD |
| fake.pw_class = ""; |
| #endif |
| fake.pw_dir = "/nonexist"; |
| fake.pw_shell = "/nonexist"; |
| |
| return (&fake); |
| } |