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      1 /* $OpenBSD: auth.c,v 1.113 2015/08/21 03:42:19 djm Exp $ */
      2 /*
      3  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      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.
     13  *
     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.
     24  */
     25 
     26 #include "includes.h"
     27 
     28 #include <sys/types.h>
     29 #include <sys/stat.h>
     30 
     31 #include <netinet/in.h>
     32 
     33 #include <errno.h>
     34 #include <fcntl.h>
     35 #ifdef HAVE_PATHS_H
     36 # include <paths.h>
     37 #endif
     38 #include <pwd.h>
     39 #ifdef HAVE_LOGIN_H
     40 #include <login.h>
     41 #endif
     42 #ifdef USE_SHADOW
     43 #include <shadow.h>
     44 #endif
     45 #ifdef HAVE_LIBGEN_H
     46 #include <libgen.h>
     47 #endif
     48 #include <stdarg.h>
     49 #include <stdio.h>
     50 #include <string.h>
     51 #include <unistd.h>
     52 #include <limits.h>
     53 
     54 #include "xmalloc.h"
     55 #include "match.h"
     56 #include "groupaccess.h"
     57 #include "log.h"
     58 #include "buffer.h"
     59 #include "misc.h"
     60 #include "servconf.h"
     61 #include "key.h"
     62 #include "hostfile.h"
     63 #include "auth.h"
     64 #include "auth-options.h"
     65 #include "canohost.h"
     66 #include "uidswap.h"
     67 #include "packet.h"
     68 #include "loginrec.h"
     69 #ifdef GSSAPI
     70 #include "ssh-gss.h"
     71 #endif
     72 #include "authfile.h"
     73 #include "monitor_wrap.h"
     74 #include "authfile.h"
     75 #include "ssherr.h"
     76 #include "compat.h"
     77 
     78 /* import */
     79 extern ServerOptions options;
     80 extern int use_privsep;
     81 extern Buffer loginmsg;
     82 extern struct passwd *privsep_pw;
     83 
     84 /* Debugging messages */
     85 Buffer auth_debug;
     86 int auth_debug_init;
     87 
     88 /*
     89  * Check if the user is allowed to log in via ssh. If user is listed
     90  * in DenyUsers or one of user's groups is listed in DenyGroups, false
     91  * will be returned. If AllowUsers isn't empty and user isn't listed
     92  * there, or if AllowGroups isn't empty and one of user's groups isn't
     93  * listed there, false will be returned.
     94  * If the user's shell is not executable, false will be returned.
     95  * Otherwise true is returned.
     96  */
     97 int
     98 allowed_user(struct passwd * pw)
     99 {
    100 	struct stat st;
    101 	const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
    102 	u_int i;
    103 #ifdef USE_SHADOW
    104 	struct spwd *spw = NULL;
    105 #endif
    106 
    107 	/* Shouldn't be called if pw is NULL, but better safe than sorry... */
    108 	if (!pw || !pw->pw_name)
    109 		return 0;
    110 
    111 #ifdef USE_SHADOW
    112 	if (!options.use_pam)
    113 		spw = getspnam(pw->pw_name);
    114 #ifdef HAS_SHADOW_EXPIRE
    115 	if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
    116 		return 0;
    117 #endif /* HAS_SHADOW_EXPIRE */
    118 #endif /* USE_SHADOW */
    119 
    120 	/* grab passwd field for locked account check */
    121 	passwd = pw->pw_passwd;
    122 #ifdef USE_SHADOW
    123 	if (spw != NULL)
    124 #ifdef USE_LIBIAF
    125 		passwd = get_iaf_password(pw);
    126 #else
    127 		passwd = spw->sp_pwdp;
    128 #endif /* USE_LIBIAF */
    129 #endif
    130 
    131 	/* check for locked account */
    132 	if (!options.use_pam && passwd && *passwd) {
    133 		int locked = 0;
    134 
    135 #ifdef LOCKED_PASSWD_STRING
    136 		if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
    137 			 locked = 1;
    138 #endif
    139 #ifdef LOCKED_PASSWD_PREFIX
    140 		if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
    141 		    strlen(LOCKED_PASSWD_PREFIX)) == 0)
    142 			 locked = 1;
    143 #endif
    144 #ifdef LOCKED_PASSWD_SUBSTR
    145 		if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
    146 			locked = 1;
    147 #endif
    148 #ifdef USE_LIBIAF
    149 		free((void *) passwd);
    150 #endif /* USE_LIBIAF */
    151 		if (locked) {
    152 			logit("User %.100s not allowed because account is locked",
    153 			    pw->pw_name);
    154 			return 0;
    155 		}
    156 	}
    157 
    158 	/*
    159 	 * Deny if shell does not exist or is not executable unless we
    160 	 * are chrooting.
    161 	 */
    162 	if (options.chroot_directory == NULL ||
    163 	    strcasecmp(options.chroot_directory, "none") == 0) {
    164 		char *shell = xstrdup((pw->pw_shell[0] == '\0') ?
    165 		    _PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */
    166 
    167 		if (stat(shell, &st) != 0) {
    168 			logit("User %.100s not allowed because shell %.100s "
    169 			    "does not exist", pw->pw_name, shell);
    170 			free(shell);
    171 			return 0;
    172 		}
    173 		if (S_ISREG(st.st_mode) == 0 ||
    174 		    (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) {
    175 			logit("User %.100s not allowed because shell %.100s "
    176 			    "is not executable", pw->pw_name, shell);
    177 			free(shell);
    178 			return 0;
    179 		}
    180 		free(shell);
    181 	}
    182 
    183 	if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
    184 	    options.num_deny_groups > 0 || options.num_allow_groups > 0) {
    185 		hostname = get_canonical_hostname(options.use_dns);
    186 		ipaddr = get_remote_ipaddr();
    187 	}
    188 
    189 	/* Return false if user is listed in DenyUsers */
    190 	if (options.num_deny_users > 0) {
    191 		for (i = 0; i < options.num_deny_users; i++)
    192 			if (match_user(pw->pw_name, hostname, ipaddr,
    193 			    options.deny_users[i])) {
    194 				logit("User %.100s from %.100s not allowed "
    195 				    "because listed in DenyUsers",
    196 				    pw->pw_name, hostname);
    197 				return 0;
    198 			}
    199 	}
    200 	/* Return false if AllowUsers isn't empty and user isn't listed there */
    201 	if (options.num_allow_users > 0) {
    202 		for (i = 0; i < options.num_allow_users; i++)
    203 			if (match_user(pw->pw_name, hostname, ipaddr,
    204 			    options.allow_users[i]))
    205 				break;
    206 		/* i < options.num_allow_users iff we break for loop */
    207 		if (i >= options.num_allow_users) {
    208 			logit("User %.100s from %.100s not allowed because "
    209 			    "not listed in AllowUsers", pw->pw_name, hostname);
    210 			return 0;
    211 		}
    212 	}
    213 	if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
    214 		/* Get the user's group access list (primary and supplementary) */
    215 		if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
    216 			logit("User %.100s from %.100s not allowed because "
    217 			    "not in any group", pw->pw_name, hostname);
    218 			return 0;
    219 		}
    220 
    221 		/* Return false if one of user's groups is listed in DenyGroups */
    222 		if (options.num_deny_groups > 0)
    223 			if (ga_match(options.deny_groups,
    224 			    options.num_deny_groups)) {
    225 				ga_free();
    226 				logit("User %.100s from %.100s not allowed "
    227 				    "because a group is listed in DenyGroups",
    228 				    pw->pw_name, hostname);
    229 				return 0;
    230 			}
    231 		/*
    232 		 * Return false if AllowGroups isn't empty and one of user's groups
    233 		 * isn't listed there
    234 		 */
    235 		if (options.num_allow_groups > 0)
    236 			if (!ga_match(options.allow_groups,
    237 			    options.num_allow_groups)) {
    238 				ga_free();
    239 				logit("User %.100s from %.100s not allowed "
    240 				    "because none of user's groups are listed "
    241 				    "in AllowGroups", pw->pw_name, hostname);
    242 				return 0;
    243 			}
    244 		ga_free();
    245 	}
    246 
    247 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
    248 	if (!sys_auth_allowed_user(pw, &loginmsg))
    249 		return 0;
    250 #endif
    251 
    252 	/* We found no reason not to let this user try to log on... */
    253 	return 1;
    254 }
    255 
    256 void
    257 auth_info(Authctxt *authctxt, const char *fmt, ...)
    258 {
    259 	va_list ap;
    260         int i;
    261 
    262 	free(authctxt->info);
    263 	authctxt->info = NULL;
    264 
    265 	va_start(ap, fmt);
    266 	i = vasprintf(&authctxt->info, fmt, ap);
    267 	va_end(ap);
    268 
    269 	if (i < 0 || authctxt->info == NULL)
    270 		fatal("vasprintf failed");
    271 }
    272 
    273 void
    274 auth_log(Authctxt *authctxt, int authenticated, int partial,
    275     const char *method, const char *submethod)
    276 {
    277 	void (*authlog) (const char *fmt,...) = verbose;
    278 	char *authmsg;
    279 
    280 	if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
    281 		return;
    282 
    283 	/* Raise logging level */
    284 	if (authenticated == 1 ||
    285 	    !authctxt->valid ||
    286 	    authctxt->failures >= options.max_authtries / 2 ||
    287 	    strcmp(method, "password") == 0)
    288 		authlog = logit;
    289 
    290 	if (authctxt->postponed)
    291 		authmsg = "Postponed";
    292 	else if (partial)
    293 		authmsg = "Partial";
    294 	else
    295 		authmsg = authenticated ? "Accepted" : "Failed";
    296 
    297 	authlog("%s %s%s%s for %s%.100s from %.200s port %d %s%s%s",
    298 	    authmsg,
    299 	    method,
    300 	    submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod,
    301 	    authctxt->valid ? "" : "invalid user ",
    302 	    authctxt->user,
    303 	    get_remote_ipaddr(),
    304 	    get_remote_port(),
    305 	    compat20 ? "ssh2" : "ssh1",
    306 	    authctxt->info != NULL ? ": " : "",
    307 	    authctxt->info != NULL ? authctxt->info : "");
    308 	free(authctxt->info);
    309 	authctxt->info = NULL;
    310 
    311 #ifdef CUSTOM_FAILED_LOGIN
    312 	if (authenticated == 0 && !authctxt->postponed &&
    313 	    (strcmp(method, "password") == 0 ||
    314 	    strncmp(method, "keyboard-interactive", 20) == 0 ||
    315 	    strcmp(method, "challenge-response") == 0))
    316 		record_failed_login(authctxt->user,
    317 		    get_canonical_hostname(options.use_dns), "ssh");
    318 # ifdef WITH_AIXAUTHENTICATE
    319 	if (authenticated)
    320 		sys_auth_record_login(authctxt->user,
    321 		    get_canonical_hostname(options.use_dns), "ssh", &loginmsg);
    322 # endif
    323 #endif
    324 #ifdef SSH_AUDIT_EVENTS
    325 	if (authenticated == 0 && !authctxt->postponed)
    326 		audit_event(audit_classify_auth(method));
    327 #endif
    328 }
    329 
    330 
    331 void
    332 auth_maxtries_exceeded(Authctxt *authctxt)
    333 {
    334 	error("maximum authentication attempts exceeded for "
    335 	    "%s%.100s from %.200s port %d %s",
    336 	    authctxt->valid ? "" : "invalid user ",
    337 	    authctxt->user,
    338 	    get_remote_ipaddr(),
    339 	    get_remote_port(),
    340 	    compat20 ? "ssh2" : "ssh1");
    341 	packet_disconnect("Too many authentication failures");
    342 	/* NOTREACHED */
    343 }
    344 
    345 /*
    346  * Check whether root logins are disallowed.
    347  */
    348 int
    349 auth_root_allowed(const char *method)
    350 {
    351 	switch (options.permit_root_login) {
    352 	case PERMIT_YES:
    353 		return 1;
    354 	case PERMIT_NO_PASSWD:
    355 		if (strcmp(method, "publickey") == 0 ||
    356 		    strcmp(method, "hostbased") == 0 ||
    357 		    strcmp(method, "gssapi-with-mic") == 0)
    358 			return 1;
    359 		break;
    360 	case PERMIT_FORCED_ONLY:
    361 		if (forced_command) {
    362 			logit("Root login accepted for forced command.");
    363 			return 1;
    364 		}
    365 		break;
    366 	}
    367 	logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
    368 	return 0;
    369 }
    370 
    371 
    372 /*
    373  * Given a template and a passwd structure, build a filename
    374  * by substituting % tokenised options. Currently, %% becomes '%',
    375  * %h becomes the home directory and %u the username.
    376  *
    377  * This returns a buffer allocated by xmalloc.
    378  */
    379 char *
    380 expand_authorized_keys(const char *filename, struct passwd *pw)
    381 {
    382 	char *file, ret[PATH_MAX];
    383 	int i;
    384 
    385 	file = percent_expand(filename, "h", pw->pw_dir,
    386 	    "u", pw->pw_name, (char *)NULL);
    387 
    388 	/*
    389 	 * Ensure that filename starts anchored. If not, be backward
    390 	 * compatible and prepend the '%h/'
    391 	 */
    392 	if (*file == '/')
    393 		return (file);
    394 
    395 	i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
    396 	if (i < 0 || (size_t)i >= sizeof(ret))
    397 		fatal("expand_authorized_keys: path too long");
    398 	free(file);
    399 	return (xstrdup(ret));
    400 }
    401 
    402 char *
    403 authorized_principals_file(struct passwd *pw)
    404 {
    405 	if (options.authorized_principals_file == NULL)
    406 		return NULL;
    407 	return expand_authorized_keys(options.authorized_principals_file, pw);
    408 }
    409 
    410 /* return ok if key exists in sysfile or userfile */
    411 HostStatus
    412 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
    413     const char *sysfile, const char *userfile)
    414 {
    415 	char *user_hostfile;
    416 	struct stat st;
    417 	HostStatus host_status;
    418 	struct hostkeys *hostkeys;
    419 	const struct hostkey_entry *found;
    420 
    421 	hostkeys = init_hostkeys();
    422 	load_hostkeys(hostkeys, host, sysfile);
    423 	if (userfile != NULL) {
    424 		user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
    425 		if (options.strict_modes &&
    426 		    (stat(user_hostfile, &st) == 0) &&
    427 		    ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
    428 		    (st.st_mode & 022) != 0)) {
    429 			logit("Authentication refused for %.100s: "
    430 			    "bad owner or modes for %.200s",
    431 			    pw->pw_name, user_hostfile);
    432 			auth_debug_add("Ignored %.200s: bad ownership or modes",
    433 			    user_hostfile);
    434 		} else {
    435 			temporarily_use_uid(pw);
    436 			load_hostkeys(hostkeys, host, user_hostfile);
    437 			restore_uid();
    438 		}
    439 		free(user_hostfile);
    440 	}
    441 	host_status = check_key_in_hostkeys(hostkeys, key, &found);
    442 	if (host_status == HOST_REVOKED)
    443 		error("WARNING: revoked key for %s attempted authentication",
    444 		    found->host);
    445 	else if (host_status == HOST_OK)
    446 		debug("%s: key for %s found at %s:%ld", __func__,
    447 		    found->host, found->file, found->line);
    448 	else
    449 		debug("%s: key for host %s not found", __func__, host);
    450 
    451 	free_hostkeys(hostkeys);
    452 
    453 	return host_status;
    454 }
    455 
    456 /*
    457  * Check a given path for security. This is defined as all components
    458  * of the path to the file must be owned by either the owner of
    459  * of the file or root and no directories must be group or world writable.
    460  *
    461  * XXX Should any specific check be done for sym links ?
    462  *
    463  * Takes a file name, its stat information (preferably from fstat() to
    464  * avoid races), the uid of the expected owner, their home directory and an
    465  * error buffer plus max size as arguments.
    466  *
    467  * Returns 0 on success and -1 on failure
    468  */
    469 int
    470 auth_secure_path(const char *name, struct stat *stp, const char *pw_dir,
    471     uid_t uid, char *err, size_t errlen)
    472 {
    473 	char buf[PATH_MAX], homedir[PATH_MAX];
    474 	char *cp;
    475 	int comparehome = 0;
    476 	struct stat st;
    477 
    478 	if (realpath(name, buf) == NULL) {
    479 		snprintf(err, errlen, "realpath %s failed: %s", name,
    480 		    strerror(errno));
    481 		return -1;
    482 	}
    483 	if (pw_dir != NULL && realpath(pw_dir, homedir) != NULL)
    484 		comparehome = 1;
    485 
    486 	if (!S_ISREG(stp->st_mode)) {
    487 		snprintf(err, errlen, "%s is not a regular file", buf);
    488 		return -1;
    489 	}
    490 	if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) ||
    491 	    (stp->st_mode & 022) != 0) {
    492 #if defined(ANDROID)
    493 		/* needed to allow root login on Android. */
    494 		if (getuid() != 0)
    495 #endif
    496 		{
    497 		snprintf(err, errlen, "bad ownership or modes for file %s",
    498 		    buf);
    499 		return -1;
    500 		}
    501 	}
    502 
    503 	/* for each component of the canonical path, walking upwards */
    504 	for (;;) {
    505 		if ((cp = dirname(buf)) == NULL) {
    506 			snprintf(err, errlen, "dirname() failed");
    507 			return -1;
    508 		}
    509 		strlcpy(buf, cp, sizeof(buf));
    510 
    511 #if !defined(ANDROID)
    512 		/* /data is owned by system user, which causes this check to fail */
    513 		if (stat(buf, &st) < 0 ||
    514 		    (!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) ||
    515 		    (st.st_mode & 022) != 0) {
    516 			snprintf(err, errlen,
    517 			    "bad ownership or modes for directory %s", buf);
    518 			return -1;
    519 		}
    520 #endif
    521 
    522 		/* If are past the homedir then we can stop */
    523 		if (comparehome && strcmp(homedir, buf) == 0)
    524 			break;
    525 
    526 		/*
    527 		 * dirname should always complete with a "/" path,
    528 		 * but we can be paranoid and check for "." too
    529 		 */
    530 		if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
    531 			break;
    532 	}
    533 	return 0;
    534 }
    535 
    536 /*
    537  * Version of secure_path() that accepts an open file descriptor to
    538  * avoid races.
    539  *
    540  * Returns 0 on success and -1 on failure
    541  */
    542 static int
    543 secure_filename(FILE *f, const char *file, struct passwd *pw,
    544     char *err, size_t errlen)
    545 {
    546 	struct stat st;
    547 
    548 	/* check the open file to avoid races */
    549 	if (fstat(fileno(f), &st) < 0) {
    550 		snprintf(err, errlen, "cannot stat file %s: %s",
    551 		    file, strerror(errno));
    552 		return -1;
    553 	}
    554 	return auth_secure_path(file, &st, pw->pw_dir, pw->pw_uid, err, errlen);
    555 }
    556 
    557 static FILE *
    558 auth_openfile(const char *file, struct passwd *pw, int strict_modes,
    559     int log_missing, char *file_type)
    560 {
    561 	char line[1024];
    562 	struct stat st;
    563 	int fd;
    564 	FILE *f;
    565 
    566 	if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1) {
    567 		if (log_missing || errno != ENOENT)
    568 			debug("Could not open %s '%s': %s", file_type, file,
    569 			   strerror(errno));
    570 		return NULL;
    571 	}
    572 
    573 	if (fstat(fd, &st) < 0) {
    574 		close(fd);
    575 		return NULL;
    576 	}
    577 	if (!S_ISREG(st.st_mode)) {
    578 		logit("User %s %s %s is not a regular file",
    579 		    pw->pw_name, file_type, file);
    580 		close(fd);
    581 		return NULL;
    582 	}
    583 	unset_nonblock(fd);
    584 	if ((f = fdopen(fd, "r")) == NULL) {
    585 		close(fd);
    586 		return NULL;
    587 	}
    588 	if (strict_modes &&
    589 	    secure_filename(f, file, pw, line, sizeof(line)) != 0) {
    590 		fclose(f);
    591 		logit("Authentication refused: %s", line);
    592 		auth_debug_add("Ignored %s: %s", file_type, line);
    593 		return NULL;
    594 	}
    595 
    596 	return f;
    597 }
    598 
    599 
    600 FILE *
    601 auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes)
    602 {
    603 	return auth_openfile(file, pw, strict_modes, 1, "authorized keys");
    604 }
    605 
    606 FILE *
    607 auth_openprincipals(const char *file, struct passwd *pw, int strict_modes)
    608 {
    609 	return auth_openfile(file, pw, strict_modes, 0,
    610 	    "authorized principals");
    611 }
    612 
    613 struct passwd *
    614 getpwnamallow(const char *user)
    615 {
    616 #ifdef HAVE_LOGIN_CAP
    617 	extern login_cap_t *lc;
    618 #ifdef BSD_AUTH
    619 	auth_session_t *as;
    620 #endif
    621 #endif
    622 	struct passwd *pw;
    623 	struct connection_info *ci = get_connection_info(1, options.use_dns);
    624 
    625 	ci->user = user;
    626 	parse_server_match_config(&options, ci);
    627 
    628 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
    629 	aix_setauthdb(user);
    630 #endif
    631 
    632 #if defined(ANDROID)
    633 	// Android has a fixed set of users. Any incoming user that we can't
    634 	// identify should be authenticated as the shell user.
    635 	if (strcmp(user, "root") && strcmp(user, "shell")) {
    636 		logit("Login name %.100s forced to shell", user);
    637 		user = "shell";
    638 	}
    639 #endif
    640 	pw = getpwnam(user);
    641 
    642 #if defined(_AIX) && defined(HAVE_SETAUTHDB)
    643 	aix_restoreauthdb();
    644 #endif
    645 #ifdef HAVE_CYGWIN
    646 	/*
    647 	 * Windows usernames are case-insensitive.  To avoid later problems
    648 	 * when trying to match the username, the user is only allowed to
    649 	 * login if the username is given in the same case as stored in the
    650 	 * user database.
    651 	 */
    652 	if (pw != NULL && strcmp(user, pw->pw_name) != 0) {
    653 		logit("Login name %.100s does not match stored username %.100s",
    654 		    user, pw->pw_name);
    655 		pw = NULL;
    656 	}
    657 #endif
    658 	if (pw == NULL) {
    659 		logit("Invalid user %.100s from %.100s",
    660 		    user, get_remote_ipaddr());
    661 #ifdef CUSTOM_FAILED_LOGIN
    662 		record_failed_login(user,
    663 		    get_canonical_hostname(options.use_dns), "ssh");
    664 #endif
    665 #ifdef SSH_AUDIT_EVENTS
    666 		audit_event(SSH_INVALID_USER);
    667 #endif /* SSH_AUDIT_EVENTS */
    668 		return (NULL);
    669 	}
    670 	if (!allowed_user(pw))
    671 		return (NULL);
    672 #ifdef HAVE_LOGIN_CAP
    673 	if ((lc = login_getclass(pw->pw_class)) == NULL) {
    674 		debug("unable to get login class: %s", user);
    675 		return (NULL);
    676 	}
    677 #ifdef BSD_AUTH
    678 	if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 ||
    679 	    auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
    680 		debug("Approval failure for %s", user);
    681 		pw = NULL;
    682 	}
    683 	if (as != NULL)
    684 		auth_close(as);
    685 #endif
    686 #endif
    687 	if (pw != NULL)
    688 		return (pwcopy(pw));
    689 	return (NULL);
    690 }
    691 
    692 /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */
    693 int
    694 auth_key_is_revoked(Key *key)
    695 {
    696 	char *fp = NULL;
    697 	int r;
    698 
    699 	if (options.revoked_keys_file == NULL)
    700 		return 0;
    701 	if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
    702 	    SSH_FP_DEFAULT)) == NULL) {
    703 		r = SSH_ERR_ALLOC_FAIL;
    704 		error("%s: fingerprint key: %s", __func__, ssh_err(r));
    705 		goto out;
    706 	}
    707 
    708 	r = sshkey_check_revoked(key, options.revoked_keys_file);
    709 	switch (r) {
    710 	case 0:
    711 		break; /* not revoked */
    712 	case SSH_ERR_KEY_REVOKED:
    713 		error("Authentication key %s %s revoked by file %s",
    714 		    sshkey_type(key), fp, options.revoked_keys_file);
    715 		goto out;
    716 	default:
    717 		error("Error checking authentication key %s %s in "
    718 		    "revoked keys file %s: %s", sshkey_type(key), fp,
    719 		    options.revoked_keys_file, ssh_err(r));
    720 		goto out;
    721 	}
    722 
    723 	/* Success */
    724 	r = 0;
    725 
    726  out:
    727 	free(fp);
    728 	return r == 0 ? 0 : 1;
    729 }
    730 
    731 void
    732 auth_debug_add(const char *fmt,...)
    733 {
    734 	char buf[1024];
    735 	va_list args;
    736 
    737 	if (!auth_debug_init)
    738 		return;
    739 
    740 	va_start(args, fmt);
    741 	vsnprintf(buf, sizeof(buf), fmt, args);
    742 	va_end(args);
    743 	buffer_put_cstring(&auth_debug, buf);
    744 }
    745 
    746 void
    747 auth_debug_send(void)
    748 {
    749 	char *msg;
    750 
    751 	if (!auth_debug_init)
    752 		return;
    753 	while (buffer_len(&auth_debug)) {
    754 		msg = buffer_get_string(&auth_debug, NULL);
    755 		packet_send_debug("%s", msg);
    756 		free(msg);
    757 	}
    758 }
    759 
    760 void
    761 auth_debug_reset(void)
    762 {
    763 	if (auth_debug_init)
    764 		buffer_clear(&auth_debug);
    765 	else {
    766 		buffer_init(&auth_debug);
    767 		auth_debug_init = 1;
    768 	}
    769 }
    770 
    771 struct passwd *
    772 fakepw(void)
    773 {
    774 	static struct passwd fake;
    775 
    776 	memset(&fake, 0, sizeof(fake));
    777 	fake.pw_name = "NOUSER";
    778 	fake.pw_passwd =
    779 	    "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
    780 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS
    781 	fake.pw_gecos = "NOUSER";
    782 #endif
    783 	fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid;
    784 	fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid;
    785 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS
    786 	fake.pw_class = "";
    787 #endif
    788 	fake.pw_dir = "/nonexist";
    789 	fake.pw_shell = "/nonexist";
    790 
    791 	return (&fake);
    792 }
    793