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/*
* Copyright (c) 2008 Seraphim Mellos <mellos@ceid.upatras.gr>
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <string.h>
#include <grp.h>
#include <pwd.h>
#define PAM_SM_AUTH
#define PAM_OPT_ROOT_ONLY "root_only"
#include <security/pam_appl.h>
#include <security/pam_modules.h>
#include <security/pam_mod_misc.h>
PAM_EXTERN int
pam_sm_authenticate(pam_handle_t * pamh, int flags,
int argc, const char * argv[])
{
struct passwd *opwd,*tpwd;
struct group *group;
const char *orig_user, *target_user;
char **user_list;
int pam_err, member;
/* Get info for target user. Who do you want to su to ? */
if ( ( (pam_err = pam_get_user(pamh, &target_user, NULL)) != PAM_SUCCESS )
|| ( orig_user == NULL ) ) {
PAM_ERROR("Error recovering username.");
return (pam_err);
}
if ( (tpwd = getpwnam(target_user)) == NULL ) {
PAM_ERROR("Could not get passwd entry for user [%s]",target_user);
return (PAM_SERVICE_ERR);
}
if ( openpam_get_option(pamh, PAM_OPT_ROOT_ONLY) ) {
/* if su to non-root -> ignore */
if (tpwd->pw_uid != 0)
return (PAM_AUTH_ERR);
}
/* Get info for originating user. Who called su? */
if ( ( (pam_err = pam_get_user(pamh, &orig_user, NULL)) != PAM_SUCCESS )
|| ( orig_user == NULL ) ) {
PAM_ERROR("Error recovering username.");
return (pam_err);
}
if ( (opwd = getpwnam(orig_user)) == NULL ) {
PAM_ERROR("Could not get passwd entry for user [%s]",orig_user);
return (PAM_SERVICE_ERR);
}
/* We now have all user info we need */
if ( (group = getgrnam("wheel")) == NULL ) {
group = getgrgid(0);
}
/* Check wheel or group with GID 0 have any members */
if (!group || (!group->gr_mem && (opwd->pw_gid != group->gr_gid))) {
PAM_LOG("Group wheel or with GID 0 has no members");
return (PAM_AUTH_ERR);
}
/* Check user's membership to the interested groups */
member=0;
user_list = group->gr_mem;
while ( !member && user_list && *(user_list) ) {
if (strncmp(*user_list, orig_user, strlen(orig_user)-1 ) == 0)
member=1;
user_list++;
}
if ( member || ( opwd->pw_gid == group->gr_gid ) ) {
PAM_LOG("Access granted for user '%s' to user '%s'", orig_user, target_user);
return (PAM_SUCCESS);
} else {
PAM_ERROR("Access denied for user '%s' to user '%s'", orig_user, target_user);
return (PAM_PERM_DENIED);
}
}
PAM_EXTERN int
pam_sm_setcred(pam_handle_t *pamh , int flags ,
int argc , const char *argv[])
{
return (PAM_SUCCESS);
}
PAM_MODULE_ENTRY("pam_wheel");
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