[openssh.git] / auth.c

/*
 * 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>

#ifdef HAVE_PATHS_H
# include <paths.h>
#endif
#ifdef HAVE_LOGIN_H
#include <login.h>
#endif
#ifdef USE_SHADOW
#include <shadow.h>
#endif

#ifdef HAVE_LIBGEN_H
#include <libgen.h>
#endif

#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 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;

	/* 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) {
		ssh_audit_event_t event;

		debug3("audit failed auth attempt, method %s euid %d",
		    method, (int)geteuid());
		/*
		 * Because the auth loop is used in both monitor and slave,
		 * we must be careful to send each event only once and with
		 * enough privs to write the event.
		 */
		event = audit_classify_auth(method);
		switch(event) {
		case SSH_AUTH_FAIL_NONE:
		case SSH_AUTH_FAIL_PASSWD:
		case SSH_AUTH_FAIL_KBDINT:
			if (geteuid() == 0)
				audit_event(event);
			break;
		case SSH_AUTH_FAIL_PUBKEY:
		case SSH_AUTH_FAIL_HOSTBASED:
		case SSH_AUTH_FAIL_GSSAPI:
			/*
			 * This is required to handle the case where privsep
			 * is enabled but it's root logging in, since
			 * use_privsep won't be cleared until after a
			 * successful login.
			 */
			if (geteuid() == 0)
				audit_event(event);
			else
				PRIVSEP(audit_event(event));
			break;
		default:
			error("unknown authentication audit event %d", event);
		}
	}
#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;

	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);

	ret = xmalloc(MAXPATHLEN);
	if (strlcpy(ret, pw->pw_dir, MAXPATHLEN) >= MAXPATHLEN ||
	    strlcat(ret, "/", MAXPATHLEN) >= MAXPATHLEN ||
	    strlcat(ret, file, MAXPATHLEN) >= MAXPATHLEN)
		fatal("expand_authorized_keys: path too long");

	xfree(file);
	return (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);
}
Commit	Line	Data
20d0f77f	1	/*
f3c7c613	2	* Copyright (c) 2000 Markus Friedl. All rights reserved.
bcbf86ec	3	*
	4	* Redistribution and use in source and binary forms, with or without
	5	* modification, are permitted provided that the following conditions
	6	* are met:
	7	* 1. Redistributions of source code must retain the above copyright
	8	* notice, this list of conditions and the following disclaimer.
	9	* 2. Redistributions in binary form must reproduce the above copyright
	10	* notice, this list of conditions and the following disclaimer in the
	11	* documentation and/or other materials provided with the distribution.
	12	*
	13	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	14	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	15	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	16	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	17	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	18	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	19	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	20	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	21	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	22	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
7368a6c8	23	*/
	24
	25	#include "includes.h"
4095f623	26
	27	#include <sys/types.h>
	28	#include <sys/stat.h>
7368a6c8	29
a75f5360	30	#ifdef HAVE_PATHS_H
6f61e0ec	31	# include <paths.h>
a75f5360	32	#endif
c1ef8333	33	#ifdef HAVE_LOGIN_H
	34	#include <login.h>
	35	#endif
f14ca4a4	36	#ifdef USE_SHADOW
4cb5ffa0	37	#include <shadow.h>
f14ca4a4	38	#endif
7368a6c8	39
b4d02860	40	#ifdef HAVE_LIBGEN_H
c8445989	41	#include <libgen.h>
b4d02860	42	#endif
c8445989	43
42f11eb2	44	#include "xmalloc.h"
	45	#include "match.h"
	46	#include "groupaccess.h"
	47	#include "log.h"
	48	#include "servconf.h"
e78a59f5	49	#include "auth.h"
59c97189	50	#include "auth-options.h"
42f11eb2	51	#include "canohost.h"
c8445989	52	#include "buffer.h"
c8445989	53	#include "bufaux.h"
d0c8ca5c	54	#include "uidswap.h"
5f1f36b5	55	#include "misc.h"
01dafcb5	56	#include "bufaux.h"
01dafcb5	57	#include "packet.h"
575e336f	58	#include "loginrec.h"
c00e4d75	59	#include "monitor_wrap.h"
e78a59f5	60
7368a6c8	61	/* import */
7368a6c8	62	extern ServerOptions options;
bc7dfc06	63	extern Buffer loginmsg;
7368a6c8	64
01dafcb5	65	/* Debugging messages */
	66	Buffer auth_debug;
	67	int auth_debug_init;
	68
7368a6c8	69	/*
c6a69271	70	* Check if the user is allowed to log in via ssh. If user is listed
	71	* in DenyUsers or one of user's groups is listed in DenyGroups, false
	72	* will be returned. If AllowUsers isn't empty and user isn't listed
	73	* there, or if AllowGroups isn't empty and one of user's groups isn't
	74	* listed there, false will be returned.
7368a6c8	75	* If the user's shell is not executable, false will be returned.
6ae2364d	76	* Otherwise true is returned.
7368a6c8	77	*/
a306f2dd	78	int
7368a6c8	79	allowed_user(struct passwd * pw)
	80	{
	81	struct stat st;
da67ae18	82	const char hostname = NULL, ipaddr = NULL, *passwd = NULL;
614dee3a	83	char *shell;
2ceb8101	84	u_int i;
f14ca4a4	85	#ifdef USE_SHADOW
3e6e3da0	86	struct spwd *spw = NULL;
e2ef2342	87	#endif
7368a6c8	88
7368a6c8	89	/* Shouldn't be called if pw is NULL, but better safe than sorry... */
c6a69271	90	if (!pw \|\| !pw->pw_name)
7368a6c8	91	return 0;
7368a6c8	92
f14ca4a4	93	#ifdef USE_SHADOW
3e6e3da0	94	if (!options.use_pam)
	95	spw = getspnam(pw->pw_name);
	96	#ifdef HAS_SHADOW_EXPIRE
f14ca4a4	97	if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw))
f14ca4a4	98	return 0;
3e6e3da0	99	#endif /* HAS_SHADOW_EXPIRE */
f14ca4a4	100	#endif /* USE_SHADOW */
3e6e3da0	101
aff51935	102	/* grab passwd field for locked account check */
f14ca4a4	103	#ifdef USE_SHADOW
3e6e3da0	104	if (spw != NULL)
26d07095	105	#if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
4c653d8e	106	passwd = get_iaf_password(pw);
4c653d8e	107	#else
3e6e3da0	108	passwd = spw->sp_pwdp;
26d07095	109	#endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
3e6e3da0	110	#else
3e6e3da0	111	passwd = pw->pw_passwd;
b57c8e20	112	#endif
b57c8e20	113
aff51935	114	/* check for locked account */
da67ae18	115	if (!options.use_pam && passwd && *passwd) {
3e6e3da0	116	int locked = 0;
	117
	118	#ifdef LOCKED_PASSWD_STRING
	119	if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0)
	120	locked = 1;
	121	#endif
	122	#ifdef LOCKED_PASSWD_PREFIX
	123	if (strncmp(passwd, LOCKED_PASSWD_PREFIX,
	124	strlen(LOCKED_PASSWD_PREFIX)) == 0)
	125	locked = 1;
	126	#endif
	127	#ifdef LOCKED_PASSWD_SUBSTR
	128	if (strstr(passwd, LOCKED_PASSWD_SUBSTR))
	129	locked = 1;
	130	#endif
26d07095	131	#if defined(HAVE_LIBIAF) && !defined(BROKEN_LIBIAF)
	132	free(passwd);
	133	#endif /* HAVE_LIBIAF && !BROKEN_LIBIAF */
3e6e3da0	134	if (locked) {
	135	logit("User %.100s not allowed because account is locked",
	136	pw->pw_name);
	137	return 0;
	138	}
	139	}
	140
301e9b01	141	/*
	142	* Get the shell from the password data. An empty shell field is
	143	* legal, and means /bin/sh.
	144	*/
	145	shell = (pw->pw_shell[0] == '\0') ? _PATH_BSHELL : pw->pw_shell;
	146
	147	/* deny if shell does not exists or is not executable */
b334badd	148	if (stat(shell, &st) != 0) {
bbe88b6d	149	logit("User %.100s not allowed because shell %.100s does not exist",
b334badd	150	pw->pw_name, shell);
7368a6c8	151	return 0;
b334badd	152	}
c390a3c8	153	if (S_ISREG(st.st_mode) == 0 \|\|
c390a3c8	154	(st.st_mode & (S_IXOTH\|S_IXUSR\|S_IXGRP)) == 0) {
bbe88b6d	155	logit("User %.100s not allowed because shell %.100s is not executable",
b334badd	156	pw->pw_name, shell);
7368a6c8	157	return 0;
b334badd	158	}
7368a6c8	159
2dcbac07	160	if (options.num_deny_users > 0 \|\| options.num_allow_users > 0 \|\|
2dcbac07	161	options.num_deny_groups > 0 \|\| options.num_allow_groups > 0) {
c5a7d788	162	hostname = get_canonical_hostname(options.use_dns);
6805fc56	163	ipaddr = get_remote_ipaddr();
	164	}
	165
7368a6c8	166	/* Return false if user is listed in DenyUsers */
7368a6c8	167	if (options.num_deny_users > 0) {
7368a6c8	168	for (i = 0; i < options.num_deny_users; i++)
762715ce	169	if (match_user(pw->pw_name, hostname, ipaddr,
b334badd	170	options.deny_users[i])) {
31de8b2b	171	logit("User %.100s from %.100s not allowed "
	172	"because listed in DenyUsers",
	173	pw->pw_name, hostname);
7368a6c8	174	return 0;
b334badd	175	}
7368a6c8	176	}
	177	/* Return false if AllowUsers isn't empty and user isn't listed there */
	178	if (options.num_allow_users > 0) {
7368a6c8	179	for (i = 0; i < options.num_allow_users; i++)
762715ce	180	if (match_user(pw->pw_name, hostname, ipaddr,
80f8f24f	181	options.allow_users[i]))
7368a6c8	182	break;
7368a6c8	183	/* i < options.num_allow_users iff we break for loop */
b334badd	184	if (i >= options.num_allow_users) {
31de8b2b	185	logit("User %.100s from %.100s not allowed because "
31de8b2b	186	"not listed in AllowUsers", pw->pw_name, hostname);
7368a6c8	187	return 0;
b334badd	188	}
7368a6c8	189	}
7368a6c8	190	if (options.num_deny_groups > 0 \|\| options.num_allow_groups > 0) {
c6a69271	191	/* Get the user's group access list (primary and supplementary) */
b334badd	192	if (ga_init(pw->pw_name, pw->pw_gid) == 0) {
31de8b2b	193	logit("User %.100s from %.100s not allowed because "
31de8b2b	194	"not in any group", pw->pw_name, hostname);
7368a6c8	195	return 0;
b334badd	196	}
7368a6c8	197
c6a69271	198	/* Return false if one of user's groups is listed in DenyGroups */
	199	if (options.num_deny_groups > 0)
	200	if (ga_match(options.deny_groups,
	201	options.num_deny_groups)) {
	202	ga_free();
31de8b2b	203	logit("User %.100s from %.100s not allowed "
	204	"because a group is listed in DenyGroups",
	205	pw->pw_name, hostname);
7368a6c8	206	return 0;
c6a69271	207	}
7368a6c8	208	/*
c6a69271	209	* Return false if AllowGroups isn't empty and one of user's groups
7368a6c8	210	* isn't listed there
7368a6c8	211	*/
c6a69271	212	if (options.num_allow_groups > 0)
	213	if (!ga_match(options.allow_groups,
	214	options.num_allow_groups)) {
	215	ga_free();
31de8b2b	216	logit("User %.100s from %.100s not allowed "
	217	"because none of user's groups are listed "
	218	"in AllowGroups", pw->pw_name, hostname);
7368a6c8	219	return 0;
c6a69271	220	}
c6a69271	221	ga_free();
7368a6c8	222	}
7368a6c8	223
bc5c2025	224	#ifdef CUSTOM_SYS_AUTH_ALLOWED_USER
5ccf88cb	225	if (!sys_auth_allowed_user(pw, &loginmsg))
bc5c2025	226	return 0;
bc5c2025	227	#endif
7368a6c8	228
	229	/* We found no reason not to let this user try to log on... */
	230	return 1;
	231	}
59c97189	232
59c97189	233	void
	234	auth_log(Authctxt authctxt, int authenticated, char method, char *info)
	235	{
	236	void (authlog) (const char fmt,...) = verbose;
	237	char *authmsg;
	238
	239	/* Raise logging level */
	240	if (authenticated == 1 \|\|
	241	!authctxt->valid \|\|
af4bd935	242	authctxt->failures >= options.max_authtries / 2 \|\|
59c97189	243	strcmp(method, "password") == 0)
a3568201	244	authlog = logit;
59c97189	245
	246	if (authctxt->postponed)
	247	authmsg = "Postponed";
	248	else
	249	authmsg = authenticated ? "Accepted" : "Failed";
	250
	251	authlog("%s %s for %s%.100s from %.200s port %d%s",
	252	authmsg,
	253	method,
d77347cc	254	authctxt->valid ? "" : "invalid user ",
fad3754c	255	authctxt->user,
59c97189	256	get_remote_ipaddr(),
	257	get_remote_port(),
	258	info);
56fd97d7	259
73d9dad3	260	#ifdef CUSTOM_FAILED_LOGIN
b6610e8f	261	if (authenticated == 0 && !authctxt->postponed &&
b6610e8f	262	(strcmp(method, "password") == 0 \|\|
6af6e631	263	strncmp(method, "keyboard-interactive", 20) == 0 \|\|
6af6e631	264	strcmp(method, "challenge-response") == 0))
575e336f	265	record_failed_login(authctxt->user,
575e336f	266	get_canonical_hostname(options.use_dns), "ssh");
73d9dad3	267	#endif
6039eeef	268	#ifdef SSH_AUDIT_EVENTS
c00e4d75	269	if (authenticated == 0 && !authctxt->postponed) {
	270	ssh_audit_event_t event;
	271
	272	debug3("audit failed auth attempt, method %s euid %d",
	273	method, (int)geteuid());
	274	/*
	275	* Because the auth loop is used in both monitor and slave,
	276	* we must be careful to send each event only once and with
	277	* enough privs to write the event.
	278	*/
	279	event = audit_classify_auth(method);
	280	switch(event) {
6039eeef	281	case SSH_AUTH_FAIL_NONE:
	282	case SSH_AUTH_FAIL_PASSWD:
	283	case SSH_AUTH_FAIL_KBDINT:
c00e4d75	284	if (geteuid() == 0)
	285	audit_event(event);
	286	break;
6039eeef	287	case SSH_AUTH_FAIL_PUBKEY:
	288	case SSH_AUTH_FAIL_HOSTBASED:
	289	case SSH_AUTH_FAIL_GSSAPI:
c00e4d75	290	/*
	291	* This is required to handle the case where privsep
	292	* is enabled but it's root logging in, since
	293	* use_privsep won't be cleared until after a
	294	* successful login.
	295	*/
	296	if (geteuid() == 0)
	297	audit_event(event);
	298	else
	299	PRIVSEP(audit_event(event));
	300	break;
	301	default:
	302	error("unknown authentication audit event %d", event);
	303	}
	304	}
	305	#endif
59c97189	306	}
	307
	308	/*
15853e93	309	* Check whether root logins are disallowed.
59c97189	310	*/
59c97189	311	int
15853e93	312	auth_root_allowed(char *method)
59c97189	313	{
15853e93	314	switch (options.permit_root_login) {
15853e93	315	case PERMIT_YES:
59c97189	316	return 1;
15853e93	317	case PERMIT_NO_PASSWD:
	318	if (strcmp(method, "password") != 0)
	319	return 1;
	320	break;
	321	case PERMIT_FORCED_ONLY:
	322	if (forced_command) {
bbe88b6d	323	logit("Root login accepted for forced command.");
15853e93	324	return 1;
	325	}
	326	break;
59c97189	327	}
bbe88b6d	328	logit("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
15853e93	329	return 0;
59c97189	330	}
c8445989	331
	332
	333	/*
	334	* Given a template and a passwd structure, build a filename
	335	* by substituting % tokenised options. Currently, %% becomes '%',
	336	* %h becomes the home directory and %u the username.
	337	*
	338	* This returns a buffer allocated by xmalloc.
	339	*/
a980cbd7	340	static char *
a980cbd7	341	expand_authorized_keys(const char filename, struct passwd pw)
c8445989	342	{
a980cbd7	343	char file, ret;
c8445989	344
a980cbd7	345	file = percent_expand(filename, "h", pw->pw_dir,
a980cbd7	346	"u", pw->pw_name, (char *)NULL);
c8445989	347
	348	/*
	349	* Ensure that filename starts anchored. If not, be backward
	350	* compatible and prepend the '%h/'
	351	*/
a980cbd7	352	if (*file == '/')
	353	return (file);
	354
	355	ret = xmalloc(MAXPATHLEN);
	356	if (strlcpy(ret, pw->pw_dir, MAXPATHLEN) >= MAXPATHLEN \|\|
	357	strlcat(ret, "/", MAXPATHLEN) >= MAXPATHLEN \|\|
	358	strlcat(ret, file, MAXPATHLEN) >= MAXPATHLEN)
	359	fatal("expand_authorized_keys: path too long");
c8445989	360
a980cbd7	361	xfree(file);
a980cbd7	362	return (ret);
c8445989	363	}
	364
	365	char *
	366	authorized_keys_file(struct passwd *pw)
	367	{
a980cbd7	368	return expand_authorized_keys(options.authorized_keys_file, pw);
c8445989	369	}
	370
	371	char *
	372	authorized_keys_file2(struct passwd *pw)
	373	{
a980cbd7	374	return expand_authorized_keys(options.authorized_keys_file2, pw);
c8445989	375	}
c8445989	376
d0c8ca5c	377	/* return ok if key exists in sysfile or userfile */
	378	HostStatus
	379	check_key_in_hostfiles(struct passwd pw, Key key, const char *host,
	380	const char sysfile, const char userfile)
	381	{
	382	Key *found;
	383	char *user_hostfile;
	384	struct stat st;
17a3011c	385	HostStatus host_status;
d0c8ca5c	386
	387	/* Check if we know the host and its host key. */
	388	found = key_new(key->type);
	389	host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
	390
	391	if (host_status != HOST_OK && userfile != NULL) {
	392	user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
	393	if (options.strict_modes &&
	394	(stat(user_hostfile, &st) == 0) &&
	395	((st.st_uid != 0 && st.st_uid != pw->pw_uid) \|\|
184eed6a	396	(st.st_mode & 022) != 0)) {
bbe88b6d	397	logit("Authentication refused for %.100s: "
d0c8ca5c	398	"bad owner or modes for %.200s",
	399	pw->pw_name, user_hostfile);
	400	} else {
	401	temporarily_use_uid(pw);
	402	host_status = check_host_in_hostfile(user_hostfile,
	403	host, key, found, NULL);
	404	restore_uid();
	405	}
	406	xfree(user_hostfile);
	407	}
	408	key_free(found);
	409
	410	debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
	411	"ok" : "not found", host);
	412	return host_status;
	413	}
	414
	415
c8445989	416	/*
c8445989	417	* Check a given file for security. This is defined as all components
d6097023	418	* of the path to the file must be owned by either the owner of
1ddf764b	419	* of the file or root and no directories must be group or world writable.
c8445989	420	*
	421	* XXX Should any specific check be done for sym links ?
	422	*
	423	* Takes an open file descriptor, the file name, a uid and and
	424	* error buffer plus max size as arguments.
	425	*
	426	* Returns 0 on success and -1 on failure
	427	*/
	428	int
6978866a	429	secure_filename(FILE f, const char file, struct passwd *pw,
6978866a	430	char *err, size_t errlen)
c8445989	431	{
6978866a	432	uid_t uid = pw->pw_uid;
76fbdd47	433	char buf[MAXPATHLEN], homedir[MAXPATHLEN];
c8445989	434	char *cp;
f6f02456	435	int comparehome = 0;
c8445989	436	struct stat st;
	437
	438	if (realpath(file, buf) == NULL) {
	439	snprintf(err, errlen, "realpath %s failed: %s", file,
	440	strerror(errno));
	441	return -1;
	442	}
f6f02456	443	if (realpath(pw->pw_dir, homedir) != NULL)
f6f02456	444	comparehome = 1;
c8445989	445
	446	/* check the open file to avoid races */
	447	if (fstat(fileno(f), &st) < 0 \|\|
	448	(st.st_uid != 0 && st.st_uid != uid) \|\|
	449	(st.st_mode & 022) != 0) {
	450	snprintf(err, errlen, "bad ownership or modes for file %s",
	451	buf);
	452	return -1;
	453	}
	454
	455	/* for each component of the canonical path, walking upwards */
	456	for (;;) {
	457	if ((cp = dirname(buf)) == NULL) {
	458	snprintf(err, errlen, "dirname() failed");
	459	return -1;
	460	}
	461	strlcpy(buf, cp, sizeof(buf));
	462
	463	debug3("secure_filename: checking '%s'", buf);
	464	if (stat(buf, &st) < 0 \|\|
	465	(st.st_uid != 0 && st.st_uid != uid) \|\|
	466	(st.st_mode & 022) != 0) {
184eed6a	467	snprintf(err, errlen,
c8445989	468	"bad ownership or modes for directory %s", buf);
	469	return -1;
	470	}
	471
afd501f9	472	/* If are passed the homedir then we can stop */
f6f02456	473	if (comparehome && strcmp(homedir, buf) == 0) {
afd501f9	474	debug3("secure_filename: terminating check at '%s'",
	475	buf);
	476	break;
	477	}
c8445989	478	/*
	479	* dirname should always complete with a "/" path,
	480	* but we can be paranoid and check for "." too
	481	*/
	482	if ((strcmp("/", buf) == 0) \|\| (strcmp(".", buf) == 0))
	483	break;
	484	}
	485	return 0;
	486	}
443fa1cd	487
	488	struct passwd *
	489	getpwnamallow(const char *user)
	490	{
1836f69f	491	#ifdef HAVE_LOGIN_CAP
	492	extern login_cap_t *lc;
	493	#ifdef BSD_AUTH
	494	auth_session_t *as;
	495	#endif
	496	#endif
443fa1cd	497	struct passwd *pw;
	498
	499	pw = getpwnam(user);
c2802d92	500	if (pw == NULL) {
227a6a97	501	logit("Invalid user %.100s from %.100s",
c2802d92	502	user, get_remote_ipaddr());
73d9dad3	503	#ifdef CUSTOM_FAILED_LOGIN
575e336f	504	record_failed_login(user,
575e336f	505	get_canonical_hostname(options.use_dns), "ssh");
819d3f09	506	#endif
6039eeef	507	#ifdef SSH_AUDIT_EVENTS
	508	audit_event(SSH_INVALID_USER);
	509	#endif /* SSH_AUDIT_EVENTS */
c2802d92	510	return (NULL);
	511	}
	512	if (!allowed_user(pw))
1836f69f	513	return (NULL);
	514	#ifdef HAVE_LOGIN_CAP
	515	if ((lc = login_getclass(pw->pw_class)) == NULL) {
	516	debug("unable to get login class: %s", user);
	517	return (NULL);
	518	}
	519	#ifdef BSD_AUTH
	520	if ((as = auth_open()) == NULL \|\| auth_setpwd(as, pw) != 0 \|\|
65721f9c	521	auth_approval(as, lc, pw->pw_name, "ssh") <= 0) {
1836f69f	522	debug("Approval failure for %s", user);
443fa1cd	523	pw = NULL;
1836f69f	524	}
	525	if (as != NULL)
	526	auth_close(as);
	527	#endif
	528	#endif
06bea668	529	if (pw != NULL)
	530	return (pwcopy(pw));
	531	return (NULL);
443fa1cd	532	}
01dafcb5	533
	534	void
	535	auth_debug_add(const char *fmt,...)
	536	{
	537	char buf[1024];
	538	va_list args;
	539
	540	if (!auth_debug_init)
	541	return;
	542
	543	va_start(args, fmt);
	544	vsnprintf(buf, sizeof(buf), fmt, args);
	545	va_end(args);
	546	buffer_put_cstring(&auth_debug, buf);
	547	}
	548
	549	void
	550	auth_debug_send(void)
	551	{
	552	char *msg;
	553
	554	if (!auth_debug_init)
	555	return;
	556	while (buffer_len(&auth_debug)) {
	557	msg = buffer_get_string(&auth_debug, NULL);
	558	packet_send_debug("%s", msg);
	559	xfree(msg);
	560	}
	561	}
	562
	563	void
	564	auth_debug_reset(void)
	565	{
	566	if (auth_debug_init)
	567	buffer_clear(&auth_debug);
	568	else {
	569	buffer_init(&auth_debug);
	570	auth_debug_init = 1;
	571	}
	572	}
96d0bf74	573
	574	struct passwd *
	575	fakepw(void)
	576	{
	577	static struct passwd fake;
	578
	579	memset(&fake, 0, sizeof(fake));
	580	fake.pw_name = "NOUSER";
	581	fake.pw_passwd =
b6453d99	582	"$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK";
96d0bf74	583	fake.pw_gecos = "NOUSER";
f6be21a0	584	fake.pw_uid = (uid_t)-1;
f6be21a0	585	fake.pw_gid = (gid_t)-1;
96d0bf74	586	#ifdef HAVE_PW_CLASS_IN_PASSWD
	587	fake.pw_class = "";
	588	#endif
	589	fake.pw_dir = "/nonexist";
	590	fake.pw_shell = "/nonexist";
	591
	592	return (&fake);
	593	}