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/*
* pam_wheel module
*
* Written by Cristian Gafton <gafton@redhat.com> 1996/09/10
* See the end of the file for Copyright Information
*
*
* 1.2 - added 'deny' and 'group=' options
* 1.1 - added 'trust' option
* 1.0 - the code is working for at least another person, so... :-)
* 0.1 - use vsyslog instead of vfprintf/syslog in _pam_log
* - return PAM_IGNORE on success (take care of sloppy sysadmins..)
* - use pam_get_user instead of pam_get_item(...,PAM_USER,...)
* - a new arg use_uid to auth the current uid instead of the
* initial (logged in) one.
* 0.0 - first release
*
* TODO:
* - try to use make_remark from pam_unix/support.c
* - consider returning on failure PAM_FAIL_NOW if the user is not
* a wheel member.
*/
#include "config.h"
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <syslog.h>
#include <stdarg.h>
#include <sys/types.h>
#include <pwd.h>
#include <grp.h>
/*
* here, we make a definition for the externally accessible function
* in this file (this definition is required for static a module
* but strongly encouraged generally) it is used to instruct the
* modules include file to define the function prototypes.
*/
#include <security/pam_modules.h>
#include <security/pam_modutil.h>
#include <security/pam_ext.h>
#include "pam_inline.h"
/* checks if a user is on a list of members of the GID 0 group */
static int is_on_list(char * const *list, const char *member)
{
while (list && *list) {
if (strcmp(*list, member) == 0)
return 1;
list++;
}
return 0;
}
/* argument parsing */
#define PAM_DEBUG_ARG 0x0001
#define PAM_USE_UID_ARG 0x0002
#define PAM_TRUST_ARG 0x0004
#define PAM_DENY_ARG 0x0010
#define PAM_ROOT_ONLY_ARG 0x0020
static int
_pam_parse (const pam_handle_t *pamh, int argc, const char **argv,
char *use_group, size_t group_length)
{
int ctrl=0;
memset(use_group, '\0', group_length);
/* step through arguments */
for (ctrl=0; argc-- > 0; ++argv) {
const char *str;
/* generic options */
if (!strcmp(*argv,"debug"))
ctrl |= PAM_DEBUG_ARG;
else if (!strcmp(*argv,"use_uid"))
ctrl |= PAM_USE_UID_ARG;
else if (!strcmp(*argv,"trust"))
ctrl |= PAM_TRUST_ARG;
else if (!strcmp(*argv,"deny"))
ctrl |= PAM_DENY_ARG;
else if (!strcmp(*argv,"root_only"))
ctrl |= PAM_ROOT_ONLY_ARG;
else if ((str = pam_str_skip_prefix(*argv, "group=")) != NULL)
strncpy(use_group, str, group_length - 1);
else {
pam_syslog(pamh, LOG_ERR, "unknown option: %s", *argv);
}
}
return ctrl;
}
static int
perform_check (pam_handle_t *pamh, int ctrl, const char *use_group)
{
const char *username = NULL;
const char *fromsu;
struct passwd *pwd, *tpwd = NULL;
struct group *grp;
int retval = PAM_AUTH_ERR;
retval = pam_get_user(pamh, &username, NULL);
if (retval != PAM_SUCCESS) {
if (ctrl & PAM_DEBUG_ARG) {
pam_syslog(pamh, LOG_DEBUG, "cannot determine user name: %s",
pam_strerror(pamh, retval));
}
return PAM_SERVICE_ERR;
}
pwd = pam_modutil_getpwnam (pamh, username);
if (!pwd) {
if (ctrl & PAM_DEBUG_ARG) {
pam_syslog(pamh, LOG_NOTICE, "unknown user %s", username);
}
return PAM_USER_UNKNOWN;
}
if (ctrl & PAM_ROOT_ONLY_ARG) {
/* su to a non uid 0 account ? */
if (pwd->pw_uid != 0) {
return PAM_IGNORE;
}
}
if (ctrl & PAM_USE_UID_ARG) {
tpwd = pam_modutil_getpwuid (pamh, getuid());
if (!tpwd) {
if (ctrl & PAM_DEBUG_ARG) {
pam_syslog(pamh, LOG_NOTICE, "who is running me ?!");
}
return PAM_SERVICE_ERR;
}
fromsu = tpwd->pw_name;
} else {
fromsu = pam_modutil_getlogin(pamh);
if (fromsu) {
tpwd = pam_modutil_getpwnam (pamh, fromsu);
}
if (!fromsu || !tpwd) {
if (ctrl & PAM_DEBUG_ARG) {
pam_syslog(pamh, LOG_NOTICE, "who is running me ?!");
}
return PAM_SERVICE_ERR;
}
}
/*
* At this point fromsu = username-of-invoker; tpwd = pwd ptr for fromsu
*/
if (!use_group[0]) {
if ((grp = pam_modutil_getgrnam (pamh, "wheel")) == NULL) {
grp = pam_modutil_getgrgid (pamh, 0);
}
} else {
grp = pam_modutil_getgrnam (pamh, use_group);
}
if (!grp || (!grp->gr_mem && (tpwd->pw_gid != grp->gr_gid))) {
if (ctrl & PAM_DEBUG_ARG) {
if (!use_group[0]) {
pam_syslog(pamh, LOG_NOTICE, "no members in a GID 0 group");
} else {
pam_syslog(pamh, LOG_NOTICE,
"no members in '%s' group", use_group);
}
}
if (ctrl & PAM_DENY_ARG) {
/* if this was meant to deny access to the members
* of this group and the group does not exist, allow
* access
*/
return PAM_IGNORE;
} else {
return PAM_AUTH_ERR;
}
}
/*
* test if the user is a member of the group, or if the
* user has the "wheel" (sic) group as its primary group.
*/
if (is_on_list(grp->gr_mem, fromsu) || (tpwd->pw_gid == grp->gr_gid)) {
if (ctrl & PAM_DENY_ARG) {
retval = PAM_PERM_DENIED;
} else if (ctrl & PAM_TRUST_ARG) {
retval = PAM_SUCCESS; /* this can be a sufficient check */
} else {
retval = PAM_IGNORE;
}
} else {
if (ctrl & PAM_DENY_ARG) {
if (ctrl & PAM_TRUST_ARG) {
retval = PAM_SUCCESS; /* this can be a sufficient check */
} else {
retval = PAM_IGNORE;
}
} else {
retval = PAM_PERM_DENIED;
}
}
if (ctrl & PAM_DEBUG_ARG) {
if (retval == PAM_IGNORE) {
pam_syslog(pamh, LOG_NOTICE,
"Ignoring access request '%s' for '%s'",
fromsu, username);
} else {
pam_syslog(pamh, LOG_NOTICE, "Access %s to '%s' for '%s'",
(retval != PAM_SUCCESS) ? "denied":"granted",
fromsu, username);
}
}
return retval;
}
/* --- authentication management functions --- */
int
pam_sm_authenticate (pam_handle_t *pamh, int flags UNUSED,
int argc, const char **argv)
{
char use_group[BUFSIZ];
int ctrl;
ctrl = _pam_parse(pamh, argc, argv, use_group, sizeof(use_group));
return perform_check(pamh, ctrl, use_group);
}
int
pam_sm_setcred (pam_handle_t *pamh UNUSED, int flags UNUSED,
int argc UNUSED, const char **argv UNUSED)
{
return PAM_SUCCESS;
}
int
pam_sm_acct_mgmt (pam_handle_t *pamh, int flags UNUSED,
int argc, const char **argv)
{
char use_group[BUFSIZ];
int ctrl;
ctrl = _pam_parse(pamh, argc, argv, use_group, sizeof(use_group));
return perform_check(pamh, ctrl, use_group);
}
/*
* Copyright (c) Cristian Gafton <gafton@redhat.com>, 1996, 1997
* 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, and the entire permission notice in its entirety,
* including the disclaimer of warranties.
* 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. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* ALTERNATIVELY, this product may be distributed under the terms of
* the GNU Public License, in which case the provisions of the GPL are
* required INSTEAD OF the above restrictions. (This clause is
* necessary due to a potential bad interaction between the GPL and
* the restrictions contained in a BSD-style copyright.)
*
* THIS SOFTWARE IS PROVIDED `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.
*/
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