[openssh.git] / auth.c

/* $OpenBSD: auth.c,v 1.83 2010/01/13 23:47:26 djm 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 <sys/param.h>

#include <netinet/in.h>

#include <errno.h>
#include <fcntl.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 <stdio.h>
#include <string.h>
#include <unistd.h>

#include "xmalloc.h"
#include "match.h"
#include "groupaccess.h"
#include "log.h"
#include "buffer.h"
#include "servconf.h"
#include "key.h"
#include "hostfile.h"
#include "auth.h"
#include "auth-options.h"
#include "canohost.h"
#include "uidswap.h"
#include "misc.h"
#include "packet.h"
#include "loginrec.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
#include "monitor_wrap.h"

/* import */
extern ServerOptions options;
extern int use_privsep;
extern Buffer loginmsg;
extern struct passwd *privsep_pw;

/* 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, *tmp, *chroot_path;
	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 */
	passwd = pw->pw_passwd;
#ifdef USE_SHADOW
	if (spw != NULL)
#ifdef USE_LIBIAF
		passwd = get_iaf_password(pw);
#else
		passwd = spw->sp_pwdp;
#endif /* USE_LIBIAF */
#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
#ifdef USE_LIBIAF
		free(passwd);
#endif /* USE_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 = xstrdup((pw->pw_shell[0] == '\0') ?
	    _PATH_BSHELL : pw->pw_shell);

	/*
	 * Amend shell if chroot is requested.
	 */
	if (options.chroot_directory != NULL &&
	    strcasecmp(options.chroot_directory, "none") != 0) {
		tmp = tilde_expand_filename(options.chroot_directory,
		    pw->pw_uid);
		chroot_path = percent_expand(tmp, "h", pw->pw_dir,
		    "u", pw->pw_name, (char *)NULL);
		xfree(tmp);
		xasprintf(&tmp, "%s/%s", chroot_path, shell);
		xfree(shell);
		shell = tmp;
		free(chroot_path);
	}

	/* 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);
		xfree(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);
		xfree(shell);
		return 0;
	}
	xfree(shell);

	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");
# ifdef WITH_AIXAUTHENTICATE
	if (authenticated)
		sys_auth_record_login(authctxt->user,
		    get_canonical_hostname(options.use_dns), "ssh", &loginmsg);
# endif
#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
 */
static 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 past 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;
}

FILE *
auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes)
{
	char line[1024];
	struct stat st;
	int fd;
	FILE *f;

	/*
	 * Open the file containing the authorized keys
	 * Fail quietly if file does not exist
	 */
	if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1) {
		if (errno != ENOENT)
			debug("Could not open keyfile '%s': %s", file,
			   strerror(errno));
		return NULL;
	}

	if (fstat(fd, &st) < 0) {
		close(fd);
		return NULL;
	}
	if (!S_ISREG(st.st_mode)) {
		logit("User %s authorized keys %s is not a regular file",
		    pw->pw_name, file);
		close(fd);
		return NULL;
	}
	unset_nonblock(fd);
	if ((f = fdopen(fd, "r")) == NULL) {
		close(fd);
		return NULL;
	}
	if (options.strict_modes &&
	    secure_filename(f, file, pw, line, sizeof(line)) != 0) {
		fclose(f);
		logit("Authentication refused: %s", line);
		return NULL;
	}

	return f;
}

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;

	parse_server_match_config(&options, user,
	    get_canonical_hostname(options.use_dns), get_remote_ipaddr());

	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 = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid;
	fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid;
#ifdef HAVE_PW_CLASS_IN_PASSWD
	fake.pw_class = "";
#endif
	fake.pw_dir = "/nonexist";
	fake.pw_shell = "/nonexist";

	return (&fake);
}
Commit	Line	Data
239542dc	1	/* $OpenBSD: auth.c,v 1.83 2010/01/13 23:47:26 djm Exp $ */
20d0f77f	2	/*
f3c7c613	3	* Copyright (c) 2000 Markus Friedl. All rights reserved.
bcbf86ec	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.
7368a6c8	24	*/
	25
	26	#include "includes.h"
4095f623	27
	28	#include <sys/types.h>
	29	#include <sys/stat.h>
536c14e8	30	#include <sys/param.h>
7368a6c8	31
8ad2db2a	32	#include <netinet/in.h>
8ad2db2a	33
028094f4	34	#include <errno.h>
f7c2a004	35	#include <fcntl.h>
a75f5360	36	#ifdef HAVE_PATHS_H
6f61e0ec	37	# include <paths.h>
a75f5360	38	#endif
b1842393	39	#include <pwd.h>
c1ef8333	40	#ifdef HAVE_LOGIN_H
	41	#include <login.h>
	42	#endif
f14ca4a4	43	#ifdef USE_SHADOW
4cb5ffa0	44	#include <shadow.h>
f14ca4a4	45	#endif
b4d02860	46	#ifdef HAVE_LIBGEN_H
c8445989	47	#include <libgen.h>
b4d02860	48	#endif
4c72fcfd	49	#include <stdarg.h>
cf851879	50	#include <stdio.h>
00146caa	51	#include <string.h>
78cb4705	52	#include <unistd.h>
c8445989	53
42f11eb2	54	#include "xmalloc.h"
	55	#include "match.h"
	56	#include "groupaccess.h"
	57	#include "log.h"
31652869	58	#include "buffer.h"
42f11eb2	59	#include "servconf.h"
31652869	60	#include "key.h"
31652869	61	#include "hostfile.h"
e78a59f5	62	#include "auth.h"
59c97189	63	#include "auth-options.h"
42f11eb2	64	#include "canohost.h"
d0c8ca5c	65	#include "uidswap.h"
5f1f36b5	66	#include "misc.h"
01dafcb5	67	#include "packet.h"
575e336f	68	#include "loginrec.h"
31652869	69	#ifdef GSSAPI
	70	#include "ssh-gss.h"
	71	#endif
c00e4d75	72	#include "monitor_wrap.h"
e78a59f5	73
7368a6c8	74	/* import */
7368a6c8	75	extern ServerOptions options;
c023a130	76	extern int use_privsep;
bc7dfc06	77	extern Buffer loginmsg;
a078cbee	78	extern struct passwd *privsep_pw;
7368a6c8	79
01dafcb5	80	/* Debugging messages */
	81	Buffer auth_debug;
	82	int auth_debug_init;
	83
7368a6c8	84	/*
c6a69271	85	* Check if the user is allowed to log in via ssh. If user is listed
	86	* in DenyUsers or one of user's groups is listed in DenyGroups, false
	87	* will be returned. If AllowUsers isn't empty and user isn't listed
	88	* there, or if AllowGroups isn't empty and one of user's groups isn't
	89	* listed there, false will be returned.
7368a6c8	90	* If the user's shell is not executable, false will be returned.
6ae2364d	91	* Otherwise true is returned.
7368a6c8	92	*/
a306f2dd	93	int
7368a6c8	94	allowed_user(struct passwd * pw)
	95	{
	96	struct stat st;
da67ae18	97	const char hostname = NULL, ipaddr = NULL, *passwd = NULL;
239542dc	98	char shell, tmp, *chroot_path;
2ceb8101	99	u_int i;
f14ca4a4	100	#ifdef USE_SHADOW
3e6e3da0	101	struct spwd *spw = NULL;
e2ef2342	102	#endif
7368a6c8	103
7368a6c8	104	/* Shouldn't be called if pw is NULL, but better safe than sorry... */
c6a69271	105	if (!pw \|\| !pw->pw_name)
7368a6c8	106	return 0;
7368a6c8	107
f14ca4a4	108	#ifdef USE_SHADOW
3e6e3da0	109	if (!options.use_pam)
	110	spw = getspnam(pw->pw_name);
	111	#ifdef HAS_SHADOW_EXPIRE
f14ca4a4	112	if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
f14ca4a4	113	return 0;
3e6e3da0	114	#endif /* HAS_SHADOW_EXPIRE */
f14ca4a4	115	#endif /* USE_SHADOW */
3e6e3da0	116
aff51935	117	/* grab passwd field for locked account check */
3fde0623	118	passwd = pw->pw_passwd;
f14ca4a4	119	#ifdef USE_SHADOW
3e6e3da0	120	if (spw != NULL)
a03acb8f	121	#ifdef USE_LIBIAF
4c653d8e	122	passwd = get_iaf_password(pw);
4c653d8e	123	#else
3e6e3da0	124	passwd = spw->sp_pwdp;
a03acb8f	125	#endif /* USE_LIBIAF */
b57c8e20	126	#endif
b57c8e20	127
aff51935	128	/* check for locked account */
da67ae18	129	if (!options.use_pam && passwd && *passwd) {
3e6e3da0	130	int locked = 0;
	131
	132	#ifdef LOCKED_PASSWD_STRING
	133	if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
	134	locked = 1;
	135	#endif
	136	#ifdef LOCKED_PASSWD_PREFIX
	137	if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
	138	strlen(LOCKED_PASSWD_PREFIX)) == 0)
	139	locked = 1;
	140	#endif
	141	#ifdef LOCKED_PASSWD_SUBSTR
	142	if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
	143	locked = 1;
	144	#endif
a03acb8f	145	#ifdef USE_LIBIAF
26d07095	146	free(passwd);
a03acb8f	147	#endif /* USE_LIBIAF */
3e6e3da0	148	if (locked) {
	149	logit("User %.100s not allowed because account is locked",
	150	pw->pw_name);
	151	return 0;
	152	}
	153	}
	154
301e9b01	155	/*
	156	* Get the shell from the password data. An empty shell field is
	157	* legal, and means /bin/sh.
	158	*/
239542dc	159	shell = xstrdup((pw->pw_shell[0] == '\0') ?
	160	_PATH_BSHELL : pw->pw_shell);
	161
	162	/*
	163	* Amend shell if chroot is requested.
	164	*/
	165	if (options.chroot_directory != NULL &&
	166	strcasecmp(options.chroot_directory, "none") != 0) {
	167	tmp = tilde_expand_filename(options.chroot_directory,
	168	pw->pw_uid);
	169	chroot_path = percent_expand(tmp, "h", pw->pw_dir,
	170	"u", pw->pw_name, (char *)NULL);
	171	xfree(tmp);
	172	xasprintf(&tmp, "%s/%s", chroot_path, shell);
	173	xfree(shell);
	174	shell = tmp;
	175	free(chroot_path);
	176	}
301e9b01	177
301e9b01	178	/* deny if shell does not exists or is not executable */
b334badd	179	if (stat(shell, &st) != 0) {
bbe88b6d	180	logit("User %.100s not allowed because shell %.100s does not exist",
b334badd	181	pw->pw_name, shell);
239542dc	182	xfree(shell);
7368a6c8	183	return 0;
b334badd	184	}
c390a3c8	185	if (S_ISREG(st.st_mode) == 0 \|\|
c390a3c8	186	(st.st_mode & (S_IXOTH\|S_IXUSR\|S_IXGRP)) == 0) {
bbe88b6d	187	logit("User %.100s not allowed because shell %.100s is not executable",
b334badd	188	pw->pw_name, shell);
239542dc	189	xfree(shell);
7368a6c8	190	return 0;
b334badd	191	}
239542dc	192	xfree(shell);
7368a6c8	193
2dcbac07	194	if (options.num_deny_users > 0 \|\| options.num_allow_users > 0 \|\|
2dcbac07	195	options.num_deny_groups > 0 \|\| options.num_allow_groups > 0) {
c5a7d788	196	hostname = get_canonical_hostname(options.use_dns);
6805fc56	197	ipaddr = get_remote_ipaddr();
	198	}
	199
7368a6c8	200	/* Return false if user is listed in DenyUsers */
7368a6c8	201	if (options.num_deny_users > 0) {
7368a6c8	202	for (i = 0; i < options.num_deny_users; i++)
762715ce	203	if (match_user(pw->pw_name, hostname, ipaddr,
b334badd	204	options.deny_users[i])) {
31de8b2b	205	logit("User %.100s from %.100s not allowed "
	206	"because listed in DenyUsers",
	207	pw->pw_name, hostname);
7368a6c8	208	return 0;
b334badd	209	}
7368a6c8	210	}
	211	/* Return false if AllowUsers isn't empty and user isn't listed there */
	212	if (options.num_allow_users > 0) {
7368a6c8	213	for (i = 0; i < options.num_allow_users; i++)
762715ce	214	if (match_user(pw->pw_name, hostname, ipaddr,
80f8f24f	215	options.allow_users[i]))
7368a6c8	216	break;
7368a6c8	217	/* i < options.num_allow_users iff we break for loop */
b334badd	218	if (i >= options.num_allow_users) {
31de8b2b	219	logit("User %.100s from %.100s not allowed because "
31de8b2b	220	"not listed in AllowUsers", pw->pw_name, hostname);
7368a6c8	221	return 0;
b334badd	222	}
7368a6c8	223	}
7368a6c8	224	if (options.num_deny_groups > 0 \|\| options.num_allow_groups > 0) {
c6a69271	225	/* Get the user's group access list (primary and supplementary) */
b334badd	226	if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
31de8b2b	227	logit("User %.100s from %.100s not allowed because "
31de8b2b	228	"not in any group", pw->pw_name, hostname);
7368a6c8	229	return 0;
b334badd	230	}
7368a6c8	231
c6a69271	232	/* Return false if one of user's groups is listed in DenyGroups */
	233	if (options.num_deny_groups > 0)
	234	if (ga_match(options.deny_groups,
	235	options.num_deny_groups)) {
	236	ga_free();
31de8b2b	237	logit("User %.100s from %.100s not allowed "
	238	"because a group is listed in DenyGroups",
	239	pw->pw_name, hostname);
7368a6c8	240	return 0;
c6a69271	241	}
7368a6c8	242	/*
c6a69271	243	* Return false if AllowGroups isn't empty and one of user's groups
7368a6c8	244	* isn't listed there
7368a6c8	245	*/
c6a69271	246	if (options.num_allow_groups > 0)
	247	if (!ga_match(options.allow_groups,
	248	options.num_allow_groups)) {
	249	ga_free();
31de8b2b	250	logit("User %.100s from %.100s not allowed "
	251	"because none of user's groups are listed "
	252	"in AllowGroups", pw->pw_name, hostname);
7368a6c8	253	return 0;
c6a69271	254	}
c6a69271	255	ga_free();
7368a6c8	256	}
7368a6c8	257
bc5c2025	258	#ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
5ccf88cb	259	if (!sys_auth_allowed_user(pw, &loginmsg))
bc5c2025	260	return 0;
bc5c2025	261	#endif
7368a6c8	262
	263	/* We found no reason not to let this user try to log on... */
	264	return 1;
	265	}
59c97189	266
59c97189	267	void
	268	auth_log(Authctxt authctxt, int authenticated, char method, char *info)
	269	{
	270	void (authlog) (const char fmt,...) = verbose;
	271	char *authmsg;
	272
c023a130	273	if (use_privsep && !mm_is_monitor() && !authctxt->postponed)
	274	return;
	275
59c97189	276	/* Raise logging level */
	277	if (authenticated == 1 \|\|
	278	!authctxt->valid \|\|
af4bd935	279	authctxt->failures >= options.max_authtries / 2 \|\|
59c97189	280	strcmp(method, "password") == 0)
a3568201	281	authlog = logit;
59c97189	282
	283	if (authctxt->postponed)
	284	authmsg = "Postponed";
	285	else
	286	authmsg = authenticated ? "Accepted" : "Failed";
	287
	288	authlog("%s %s for %s%.100s from %.200s port %d%s",
	289	authmsg,
	290	method,
d77347cc	291	authctxt->valid ? "" : "invalid user ",
fad3754c	292	authctxt->user,
59c97189	293	get_remote_ipaddr(),
	294	get_remote_port(),
	295	info);
56fd97d7	296
73d9dad3	297	#ifdef CUSTOM_FAILED_LOGIN
b6610e8f	298	if (authenticated == 0 && !authctxt->postponed &&
b6610e8f	299	(strcmp(method, "password") == 0 \|\|
6af6e631	300	strncmp(method, "keyboard-interactive", 20) == 0 \|\|
6af6e631	301	strcmp(method, "challenge-response") == 0))
575e336f	302	record_failed_login(authctxt->user,
575e336f	303	get_canonical_hostname(options.use_dns), "ssh");
6545dd0b	304	# ifdef WITH_AIXAUTHENTICATE
	305	if (authenticated)
	306	sys_auth_record_login(authctxt->user,
	307	get_canonical_hostname(options.use_dns), "ssh", &loginmsg);
	308	# endif
73d9dad3	309	#endif
6039eeef	310	#ifdef SSH_AUDIT_EVENTS
2ae7f715	311	if (authenticated == 0 && !authctxt->postponed)
2ae7f715	312	audit_event(audit_classify_auth(method));
c00e4d75	313	#endif
59c97189	314	}
	315
	316	/*
15853e93	317	* Check whether root logins are disallowed.
59c97189	318	*/
59c97189	319	int
15853e93	320	auth_root_allowed(char *method)
59c97189	321	{
15853e93	322	switch (options.permit_root_login) {
15853e93	323	case PERMIT_YES:
59c97189	324	return 1;
15853e93	325	case PERMIT_NO_PASSWD:
	326	if (strcmp(method, "password") != 0)
	327	return 1;
	328	break;
	329	case PERMIT_FORCED_ONLY:
	330	if (forced_command) {
bbe88b6d	331	logit("Root login accepted for forced command.");
15853e93	332	return 1;
	333	}
	334	break;
59c97189	335	}
bbe88b6d	336	logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
15853e93	337	return 0;
59c97189	338	}
c8445989	339
	340
	341	/*
	342	* Given a template and a passwd structure, build a filename
	343	* by substituting % tokenised options. Currently, %% becomes '%',
	344	* %h becomes the home directory and %u the username.
	345	*
	346	* This returns a buffer allocated by xmalloc.
	347	*/
a980cbd7	348	static char *
a980cbd7	349	expand_authorized_keys(const char filename, struct passwd pw)
c8445989	350	{
52e3daed	351	char *file, ret[MAXPATHLEN];
52e3daed	352	int i;
c8445989	353
a980cbd7	354	file = percent_expand(filename, "h", pw->pw_dir,
a980cbd7	355	"u", pw->pw_name, (char *)NULL);
c8445989	356
	357	/*
	358	* Ensure that filename starts anchored. If not, be backward
	359	* compatible and prepend the '%h/'
	360	*/
a980cbd7	361	if (*file == '/')
	362	return (file);
	363
52e3daed	364	i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file);
52e3daed	365	if (i < 0 \|\| (size_t)i >= sizeof(ret))
a980cbd7	366	fatal("expand_authorized_keys: path too long");
a980cbd7	367	xfree(file);
52e3daed	368	return (xstrdup(ret));
c8445989	369	}
	370
	371	char *
	372	authorized_keys_file(struct passwd *pw)
	373	{
a980cbd7	374	return expand_authorized_keys(options.authorized_keys_file, pw);
c8445989	375	}
	376
	377	char *
	378	authorized_keys_file2(struct passwd *pw)
	379	{
a980cbd7	380	return expand_authorized_keys(options.authorized_keys_file2, pw);
c8445989	381	}
c8445989	382
d0c8ca5c	383	/* return ok if key exists in sysfile or userfile */
	384	HostStatus
	385	check_key_in_hostfiles(struct passwd pw, Key key, const char *host,
	386	const char sysfile, const char userfile)
	387	{
	388	Key *found;
	389	char *user_hostfile;
	390	struct stat st;
17a3011c	391	HostStatus host_status;
d0c8ca5c	392
	393	/* Check if we know the host and its host key. */
	394	found = key_new(key->type);
	395	host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
	396
	397	if (host_status != HOST_OK && userfile != NULL) {
	398	user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
	399	if (options.strict_modes &&
	400	(stat(user_hostfile, &st) == 0) &&
	401	((st.st_uid != 0 && st.st_uid != pw->pw_uid) \|\|
184eed6a	402	(st.st_mode & 022) != 0)) {
bbe88b6d	403	logit("Authentication refused for %.100s: "
d0c8ca5c	404	"bad owner or modes for %.200s",
	405	pw->pw_name, user_hostfile);
	406	} else {
	407	temporarily_use_uid(pw);
	408	host_status = check_host_in_hostfile(user_hostfile,
	409	host, key, found, NULL);
	410	restore_uid();
	411	}
	412	xfree(user_hostfile);
	413	}
	414	key_free(found);
	415
	416	debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
	417	"ok" : "not found", host);
	418	return host_status;
	419	}
	420
	421
c8445989	422	/*
c8445989	423	* Check a given file for security. This is defined as all components
d6097023	424	* of the path to the file must be owned by either the owner of
1ddf764b	425	* of the file or root and no directories must be group or world writable.
c8445989	426	*
	427	* XXX Should any specific check be done for sym links ?
	428	*
	429	* Takes an open file descriptor, the file name, a uid and and
	430	* error buffer plus max size as arguments.
	431	*
	432	* Returns 0 on success and -1 on failure
	433	*/
f7c2a004	434	static int
6978866a	435	secure_filename(FILE f, const char file, struct passwd *pw,
6978866a	436	char *err, size_t errlen)
c8445989	437	{
6978866a	438	uid_t uid = pw->pw_uid;
76fbdd47	439	char buf[MAXPATHLEN], homedir[MAXPATHLEN];
c8445989	440	char *cp;
f6f02456	441	int comparehome = 0;
c8445989	442	struct stat st;
	443
	444	if (realpath(file, buf) == NULL) {
	445	snprintf(err, errlen, "realpath %s failed: %s", file,
	446	strerror(errno));
	447	return -1;
	448	}
f6f02456	449	if (realpath(pw->pw_dir, homedir) != NULL)
f6f02456	450	comparehome = 1;
c8445989	451
	452	/* check the open file to avoid races */
	453	if (fstat(fileno(f), &st) < 0 \|\|
	454	(st.st_uid != 0 && st.st_uid != uid) \|\|
	455	(st.st_mode & 022) != 0) {
	456	snprintf(err, errlen, "bad ownership or modes for file %s",
	457	buf);
	458	return -1;
	459	}
	460
	461	/* for each component of the canonical path, walking upwards */
	462	for (;;) {
	463	if ((cp = dirname(buf)) == NULL) {
	464	snprintf(err, errlen, "dirname() failed");
	465	return -1;
	466	}
	467	strlcpy(buf, cp, sizeof(buf));
	468
	469	debug3("secure_filename: checking '%s'", buf);
	470	if (stat(buf, &st) < 0 \|\|
	471	(st.st_uid != 0 && st.st_uid != uid) \|\|
	472	(st.st_mode & 022) != 0) {
184eed6a	473	snprintf(err, errlen,
c8445989	474	"bad ownership or modes for directory %s", buf);
	475	return -1;
	476	}
	477
52e1856c	478	/* If are past the homedir then we can stop */
f6f02456	479	if (comparehome && strcmp(homedir, buf) == 0) {
afd501f9	480	debug3("secure_filename: terminating check at '%s'",
	481	buf);
	482	break;
	483	}
c8445989	484	/*
	485	* dirname should always complete with a "/" path,
	486	* but we can be paranoid and check for "." too
	487	*/
	488	if ((strcmp("/", buf) == 0) \|\| (strcmp(".", buf) == 0))
	489	break;
	490	}
	491	return 0;
	492	}
443fa1cd	493
f7c2a004	494	FILE *
	495	auth_openkeyfile(const char file, struct passwd pw, int strict_modes)
	496	{
	497	char line[1024];
	498	struct stat st;
	499	int fd;
	500	FILE *f;
	501
	502	/*
	503	* Open the file containing the authorized keys
	504	* Fail quietly if file does not exist
	505	*/
5deb8b6e	506	if ((fd = open(file, O_RDONLY\|O_NONBLOCK)) == -1) {
	507	if (errno != ENOENT)
	508	debug("Could not open keyfile '%s': %s", file,
	509	strerror(errno));
f7c2a004	510	return NULL;
5deb8b6e	511	}
f7c2a004	512
	513	if (fstat(fd, &st) < 0) {
	514	close(fd);
	515	return NULL;
	516	}
	517	if (!S_ISREG(st.st_mode)) {
	518	logit("User %s authorized keys %s is not a regular file",
	519	pw->pw_name, file);
	520	close(fd);
	521	return NULL;
	522	}
	523	unset_nonblock(fd);
	524	if ((f = fdopen(fd, "r")) == NULL) {
	525	close(fd);
	526	return NULL;
	527	}
	528	if (options.strict_modes &&
	529	secure_filename(f, file, pw, line, sizeof(line)) != 0) {
	530	fclose(f);
	531	logit("Authentication refused: %s", line);
	532	return NULL;
	533	}
	534
	535	return f;
	536	}
	537
443fa1cd	538	struct passwd *
	539	getpwnamallow(const char *user)
	540	{
1836f69f	541	#ifdef HAVE_LOGIN_CAP
	542	extern login_cap_t *lc;
	543	#ifdef BSD_AUTH
	544	auth_session_t *as;
	545	#endif
	546	#endif
443fa1cd	547	struct passwd *pw;
443fa1cd	548
d231781a	549	parse_server_match_config(&options, user,
	550	get_canonical_hostname(options.use_dns), get_remote_ipaddr());
	551
443fa1cd	552	pw = getpwnam(user);
c2802d92	553	if (pw == NULL) {
227a6a97	554	logit("Invalid user %.100s from %.100s",
c2802d92	555	user, get_remote_ipaddr());
73d9dad3	556	#ifdef CUSTOM_FAILED_LOGIN
575e336f	557	record_failed_login(user,
575e336f	558	get_canonical_hostname(options.use_dns), "ssh");
819d3f09	559	#endif
6039eeef	560	#ifdef SSH_AUDIT_EVENTS
	561	audit_event(SSH_INVALID_USER);
	562	#endif /* SSH_AUDIT_EVENTS */
c2802d92	563	return (NULL);
	564	}
	565	if (!allowed_user(pw))
1836f69f	566	return (NULL);
	567	#ifdef HAVE_LOGIN_CAP
	568	if ((lc = login_getclass(pw->pw_class)) == NULL) {
	569	debug("unable to get login class: %s", user);
	570	return (NULL);
	571	}
	572	#ifdef BSD_AUTH
	573	if ((as = auth_open()) == NULL \|\| auth_setpwd(as, pw) != 0 \|\|
65721f9c	574	auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
1836f69f	575	debug("Approval failure for %s", user);
443fa1cd	576	pw = NULL;
1836f69f	577	}
	578	if (as != NULL)
	579	auth_close(as);
	580	#endif
	581	#endif
06bea668	582	if (pw != NULL)
	583	return (pwcopy(pw));
	584	return (NULL);
443fa1cd	585	}
01dafcb5	586
	587	void
	588	auth_debug_add(const char *fmt,...)
	589	{
	590	char buf[1024];
	591	va_list args;
	592
	593	if (!auth_debug_init)
	594	return;
	595
	596	va_start(args, fmt);
	597	vsnprintf(buf, sizeof(buf), fmt, args);
	598	va_end(args);
	599	buffer_put_cstring(&auth_debug, buf);
	600	}
	601
	602	void
	603	auth_debug_send(void)
	604	{
	605	char *msg;
	606
	607	if (!auth_debug_init)
	608	return;
	609	while (buffer_len(&auth_debug)) {
	610	msg = buffer_get_string(&auth_debug, NULL);
	611	packet_send_debug("%s", msg);
	612	xfree(msg);
	613	}
	614	}
	615
	616	void
	617	auth_debug_reset(void)
	618	{
	619	if (auth_debug_init)
	620	buffer_clear(&auth_debug);
	621	else {
	622	buffer_init(&auth_debug);
	623	auth_debug_init = 1;
	624	}
	625	}
96d0bf74	626
	627	struct passwd *
	628	fakepw(void)
	629	{
	630	static struct passwd fake;
	631
	632	memset(&fake, 0, sizeof(fake));
	633	fake.pw_name = "NOUSER";
	634	fake.pw_passwd =
b6453d99	635	"$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
96d0bf74	636	fake.pw_gecos = "NOUSER";
2b563deb	637	fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid;
2b563deb	638	fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid;
96d0bf74	639	#ifdef HAVE_PW_CLASS_IN_PASSWD
	640	fake.pw_class = "";
	641	#endif
	642	fake.pw_dir = "/nonexist";
	643	fake.pw_shell = "/nonexist";
	644
	645	return (&fake);
	646	}