/* $OpenBSD: auth.c,v 1.154 2022/02/23 11:17:10 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/socket.h>
#include <sys/wait.h>
#include <netinet/in.h>
#include <stdlib.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
#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include <netdb.h>
#include <time.h>
#include "xmalloc.h"
#include "match.h"
#include "groupaccess.h"
#include "log.h"
#include "sshbuf.h"
#include "misc.h"
#include "servconf.h"
#include "sshkey.h"
#include "hostfile.h"
#include "auth.h"
#include "auth-options.h"
#include "canohost.h"
#include "uidswap.h"
#include "packet.h"
#include "loginrec.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
#include "authfile.h"
#include "monitor_wrap.h"
#include "ssherr.h"
#include "compat.h"
#include "channels.h"
/* import */
extern ServerOptions options;
extern struct include_list includes;
extern int use_privsep;
extern struct sshbuf *loginmsg;
extern struct passwd *privsep_pw;
extern struct sshauthopt *auth_opts;
/* Debugging messages */
static struct sshbuf *auth_debug;
/*
* 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 ssh *ssh, struct passwd * pw)
{
struct stat st;
const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL;
u_int i;
int r;
/* Shouldn't be called if pw is NULL, but better safe than sorry... */
if (!pw || !pw->pw_name)
return 0;
if (!options.use_pam && platform_locked_account(pw)) {
logit("User %.100s not allowed because account is locked",
pw->pw_name);
return 0;
}
/*
* Deny if shell does not exist or is not executable unless we
* are chrooting.
*/
if (options.chroot_directory == NULL ||
strcasecmp(options.chroot_directory, "none") == 0) {
char *shell = xstrdup((pw->pw_shell[0] == '\0') ?
_PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */
if (stat(shell, &st) == -1) {
logit("User %.100s not allowed because shell %.100s "
"does not exist", pw->pw_name, shell);
free(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);
free(shell);
return 0;
}
free(shell);
}
if (options.num_deny_users > 0 || options.num_allow_users > 0 ||
options.num_deny_groups > 0 || options.num_allow_groups > 0) {
hostname = auth_get_canonical_hostname(ssh, options.use_dns);
ipaddr = ssh_remote_ipaddr(ssh);
}
/* Return false if user is listed in DenyUsers */
if (options.num_deny_users > 0) {
for (i = 0; i < options.num_deny_users; i++) {
r = match_user(pw->pw_name, hostname, ipaddr,
options.<