278 lines
8.0 KiB
C
278 lines
8.0 KiB
C
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/* pam_wheel module */
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/*
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* Written by Cristian Gafton <gafton@redhat.com> 1996/09/10
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* See the end of the file for Copyright Information
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*
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*
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* 1.2 - added 'deny' and 'group=' options
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* 1.1 - added 'trust' option
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* 1.0 - the code is working for at least another person, so... :-)
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* 0.1 - use vsyslog instead of vfprintf/syslog in _pam_log
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* - return PAM_IGNORE on success (take care of sloppy sysadmins..)
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* - use pam_get_user instead of pam_get_item(...,PAM_USER,...)
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* - a new arg use_uid to auth the current uid instead of the
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* initial (logged in) one.
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* 0.0 - first release
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*
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* TODO:
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* - try to use make_remark from pam_unix/support.c
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* - consider returning on failure PAM_FAIL_NOW if the user is not
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* a wheel member.
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*/
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#include <stdio.h>
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#define __USE_BSD
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#include <unistd.h>
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#include <string.h>
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#include <syslog.h>
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#include <stdarg.h>
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#include <sys/types.h>
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#ifdef HAVE_PWDBLIB
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# include <pwdb/pwdb_public.h>
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#else
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# include <pwd.h>
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# include <grp.h>
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#endif
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/*
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* here, we make a definition for the externally accessible function
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* in this file (this definition is required for static a module
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* but strongly encouraged generally) it is used to instruct the
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* modules include file to define the function prototypes.
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*/
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#define PAM_SM_AUTH
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#include <security/pam_modules.h>
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/* variables */
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static char use_group[BUFSIZ];
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/* some syslogging */
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static void _pam_log(int err, const char *format, ...)
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{
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va_list args;
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va_start(args, format);
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openlog("PAM-Wheel", LOG_CONS|LOG_PID, LOG_AUTH);
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vsyslog(err, format, args);
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va_end(args);
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closelog();
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}
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/* checks if a user is on a list of members of the GID 0 group */
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static int is_on_list(char * const *list, const char *member)
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{
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while (*list) {
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if (strcmp(*list, member) == 0)
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return 1;
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list++;
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}
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return 0;
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}
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/* argument parsing */
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#define PAM_DEBUG_ARG 0x0001
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#define PAM_USE_UID_ARG 0x0002
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#define PAM_TRUST_ARG 0x0004
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#define PAM_DENY_ARG 0x0010
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static int _pam_parse(int argc, const char **argv)
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{
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int ctrl=0;
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/* step through arguments */
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for (ctrl=0; argc-- > 0; ++argv) {
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/* generic options */
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if (!strcmp(*argv,"debug"))
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ctrl |= PAM_DEBUG_ARG;
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else if (!strcmp(*argv,"use_uid"))
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ctrl |= PAM_USE_UID_ARG;
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else if (!strcmp(*argv,"trust"))
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ctrl |= PAM_TRUST_ARG;
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else if (!strcmp(*argv,"deny"))
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ctrl |= PAM_DENY_ARG;
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else if (!strncmp(*argv,"group=",6))
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strcpy(use_group,*argv+6);
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else {
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_pam_log(LOG_ERR,"pam_parse: unknown option; %s",*argv);
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}
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}
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return ctrl;
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}
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/* --- authentication management functions (only) --- */
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PAM_EXTERN
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int pam_sm_authenticate(pam_handle_t *pamh,int flags,int argc
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,const char **argv)
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{
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int ctrl;
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const char *username;
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char *fromsu;
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struct passwd *pwd, *tpwd;
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struct group *grp;
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int retval = PAM_AUTH_ERR;
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/* Init the optional group */
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bzero(use_group,sizeof(use_group));
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ctrl = _pam_parse(argc, argv);
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retval = pam_get_user(pamh,&username,NULL);
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if ((retval != PAM_SUCCESS) || (!username)) {
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if (ctrl & PAM_DEBUG_ARG)
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_pam_log(LOG_DEBUG,"can not get the username");
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return PAM_SERVICE_ERR;
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}
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/* su to a uid 0 account ? */
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pwd = getpwnam(username);
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if (!pwd) {
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if (ctrl & PAM_DEBUG_ARG)
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_pam_log(LOG_NOTICE,"unknown user %s",username);
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return PAM_USER_UNKNOWN;
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}
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/* Now we know that the username exists, pass on to other modules...
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* the call to pam_get_user made this obsolete, so is commented out
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*
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* pam_set_item(pamh,PAM_USER,(const void *)username);
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*/
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/* is this user an UID 0 account ? */
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if(pwd->pw_uid) {
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/* no need to check for wheel */
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return PAM_IGNORE;
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}
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if (ctrl & PAM_USE_UID_ARG) {
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tpwd = getpwuid(getuid());
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if (!tpwd) {
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if (ctrl & PAM_DEBUG_ARG)
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_pam_log(LOG_NOTICE,"who is running me ?!");
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return PAM_SERVICE_ERR;
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}
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fromsu = tpwd->pw_name;
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} else {
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fromsu = getlogin();
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if (!fromsu) {
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if (ctrl & PAM_DEBUG_ARG)
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_pam_log(LOG_NOTICE,"who is running me ?!");
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return PAM_SERVICE_ERR;
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}
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}
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if (!use_group[0])
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grp = getgrgid(0);
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else
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grp = getgrnam(use_group);
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if (!grp || !grp->gr_mem) {
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if (ctrl & PAM_DEBUG_ARG) {
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if (!use_group[0])
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_pam_log(LOG_NOTICE,"no members in a GID 0 group");
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else
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_pam_log(LOG_NOTICE,"no members in '%s' group",use_group);
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}
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if (ctrl & PAM_DENY_ARG)
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/* if this was meant to deny access to the members
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* of this group and the group does not exist, allow
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* access
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*/
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return PAM_IGNORE;
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else
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return PAM_AUTH_ERR;
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}
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if (is_on_list(grp->gr_mem, fromsu)) {
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if (ctrl & PAM_DEBUG_ARG)
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_pam_log(LOG_NOTICE,"Access %s to '%s' for '%s'",
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(ctrl & PAM_DENY_ARG)?"denied":"granted",
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fromsu,username);
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if (ctrl & PAM_DENY_ARG)
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return PAM_PERM_DENIED;
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else
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if (ctrl & PAM_TRUST_ARG)
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return PAM_SUCCESS;
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else
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return PAM_IGNORE;
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}
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if (ctrl & PAM_DEBUG_ARG)
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_pam_log(LOG_NOTICE,"Access %s for '%s' to '%s'",
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(ctrl & PAM_DENY_ARG)?"granted":"denied",fromsu,username);
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if (ctrl & PAM_DENY_ARG)
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return PAM_SUCCESS;
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else
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return PAM_PERM_DENIED;
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}
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PAM_EXTERN
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int pam_sm_setcred(pam_handle_t *pamh,int flags,int argc
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,const char **argv)
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{
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return PAM_SUCCESS;
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}
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#ifdef PAM_STATIC
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/* static module data */
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struct pam_module _pam_wheel_modstruct = {
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"pam_wheel",
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pam_sm_authenticate,
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pam_sm_setcred,
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NULL,
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NULL,
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NULL,
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NULL,
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};
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#endif
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/*
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* Copyright (c) Cristian Gafton <gafton@redhat.com>, 1996, 1997
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* All rights reserved
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, and the entire permission notice in its entirety,
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* including the disclaimer of warranties.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior
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* written permission.
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*
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* ALTERNATIVELY, this product may be distributed under the terms of
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* the GNU Public License, in which case the provisions of the GPL are
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* required INSTEAD OF the above restrictions. (This clause is
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* necessary due to a potential bad interaction between the GPL and
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* the restrictions contained in a BSD-style copyright.)
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*
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* THIS SOFTWARE IS PROVIDED `AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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