NetBSD/crypto/dist/ssh/auth.c

282 lines
8.9 KiB
C

/* $NetBSD: auth.c,v 1.1.1.2 2001/01/14 04:50:00 itojun Exp $ */
/*-
* Copyright (c) 2000 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe.
*
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``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 FOUNDATION OR CONTRIBUTORS
* 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.
*/
/*
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*
*
* 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.
*/
/* from OpenBSD: auth.c,v 1.11 2000/10/11 20:27:23 markus Exp */
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: auth.c,v 1.1.1.2 2001/01/14 04:50:00 itojun Exp $");
#endif
#include "includes.h"
#include "xmalloc.h"
#include "rsa.h"
#include "ssh.h"
#include "pty.h"
#include "packet.h"
#include "buffer.h"
#include "mpaux.h"
#include "servconf.h"
#include "compat.h"
#include "channels.h"
#include "match.h"
#include "bufaux.h"
#include "ssh2.h"
#include "auth.h"
#include "session.h"
#include <login_cap.h>
/* import */
extern ServerOptions options;
/*
* Check if the user is allowed to log in via ssh. If user is listed in
* DenyUsers or user's primary group 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 user 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;
struct group *grp;
const char *shell;
int i, match_name, match_ip;
login_cap_t *lc;
const char *hostname, *ipaddr;
char *cap_hlist, *hp;
hostname = get_canonical_hostname();
ipaddr = get_remote_ipaddr();
/* Shouldn't be called if pw is NULL, but better safe than sorry... */
if (pw == NULL)
goto denied;
lc = login_getclass(pw->pw_class);
/*
* Check the deny list.
*/
cap_hlist = login_getcapstr(lc, "host.deny", NULL, NULL);
if (cap_hlist != NULL) {
hp = strtok(cap_hlist, ",");
while (hp != NULL) {
match_name = match_hostname(hostname,
hp, strlen(hp));
match_ip = match_hostname(ipaddr,
hp, strlen(hp));
/*
* Only a positive match here causes a "deny".
*/
if (match_name > 0 || match_ip > 0) {
free(cap_hlist);
login_close(lc);
goto denied;
}
hp = strtok(NULL, ",");
}
free(cap_hlist);
}
/*
* Check the allow list. If the allow list exists, and the
* remote host is not in it, the user is implicitly denied.
*/
cap_hlist = login_getcapstr(lc, "host.allow", NULL, NULL);
if (cap_hlist != NULL) {
hp = strtok(cap_hlist, ",");
if (hp == NULL) {
/* Just in case there's an empty string... */
free(cap_hlist);
login_close(lc);
goto denied;
}
while (hp != NULL) {
match_name = match_hostname(hostname,
hp, strlen(hp));
match_ip = match_hostname(ipaddr,
hp, strlen(hp));
/*
* Negative match causes an immediate "deny".
* Positive match causes us to break out
* of the loop (allowing a fallthrough).
*/
if (match_name < 0 || match_ip < 0) {
free(cap_hlist);
login_close(lc);
goto denied;
}
if (match_name > 0 || match_ip > 0)
break;
}
free(cap_hlist);
if (hp == NULL) {
login_close(lc);
goto denied;
}
}
login_close(lc);
/*
* 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.
* XXX Should check to see if it is executable by the
* XXX requesting user. --thorpej
*/
if (stat(shell, &st) != 0)
goto denied;
if (S_ISREG(st.st_mode) == 0 ||
(st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0)
goto denied;
/*
* XXX Consider nuking {Allow,Deny}{Users,Groups}. We have the
* XXX login_cap(3) mechanism which covers all other types of
* XXX logins, too.
*/
/* Return false if user is listed in DenyUsers */
if (options.num_deny_users > 0) {
if (pw->pw_name == NULL)
goto denied;
for (i = 0; i < options.num_deny_users; i++)
if (match_pattern(pw->pw_name, options.deny_users[i]))
goto denied;
}
/* Return false if AllowUsers isn't empty and user isn't listed there */
if (options.num_allow_users > 0) {
if (pw->pw_name == NULL)
goto denied;
for (i = 0; i < options.num_allow_users; i++)
if (match_pattern(pw->pw_name, options.allow_users[i]))
break;
/* i < options.num_allow_users iff we break for loop */
if (i >= options.num_allow_users)
goto denied;
}
/* Get the primary group name if we need it. Return false if it fails */
if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
grp = getgrgid(pw->pw_gid);
if (grp == NULL)
goto denied;
/* Return false if user's group is listed in DenyGroups */
if (options.num_deny_groups > 0) {
if (grp->gr_name == NULL)
goto denied;
for (i = 0; i < options.num_deny_groups; i++)
if (match_pattern(grp->gr_name,
options.deny_groups[i]))
goto denied;
}
/*
* Return false if AllowGroups isn't empty and user's group
* isn't listed there
*/
if (options.num_allow_groups > 0) {
if (grp->gr_name == NULL)
goto denied;
for (i = 0; i < options.num_allow_groups; i++)
if (match_pattern(grp->gr_name,
options.allow_groups[i]))
break;
/* i < options.num_allow_groups iff we break for
loop */
if (i >= options.num_allow_groups)
goto denied;
}
}
/* We found no reason not to let this user try to log on... */
return 1;
denied:
/* XXX Need to add notice() --thorpej */
log("Denied connection for %.200s from %.200s [%.200s] port %d.\n",
pw == NULL ? "<unknown>" : pw->pw_name, hostname, ipaddr,
get_remote_port());
return (0);
}