lib/pam_module/pam_nologin/pam_nologin.c

   1 /*-
   2  * Copyright 2001 Mark R V Murray
   3  * All rights reserved.
   4  * Copyright (c) 2001 Networks Associates Technology, Inc.
   5  * All rights reserved.
   6  *
   7  * Portions of this software were developed for the FreeBSD Project by
   8  * ThinkSec AS and NAI Labs, the Security Research Division of Network
   9  * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
  10  * ("CBOSS"), as part of the DARPA CHATS research program.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. The name of the author may not be used to endorse or promote
  21  *    products derived from this software without specific prior written
  22  *    permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  * $FreeBSD: src/lib/libpam/modules/pam_nologin/pam_nologin.c,v 1.13 2007/06/14 13:07:06 yar Exp $
  37  * $DragonFly: src/lib/pam_module/pam_nologin/pam_nologin.c,v 1.1 2008/01/02 17:41:30 matthias Exp $
  38  */
  39
  40 #include <sys/cdefs.h>
  41
  42 #include <sys/types.h>
  43 #include <sys/stat.h>
  44 #include <fcntl.h>
  45 #include <login_cap.h>
  46 #include <pwd.h>
  47 #include <stdio.h>
  48 #include <stdlib.h>
  49 #include <unistd.h>
  50
  51 #define PAM_SM_ACCOUNT
  52
  53 #include <security/pam_appl.h>
  54 #include <security/pam_modules.h>
  55 #include <security/pam_mod_misc.h>
  56
  57 #define _PATH_NOLOGIN   "/var/run/nologin"
  58
  59 static char nologin_def[] = _PATH_NOLOGIN;
  60
  61 PAM_EXTERN int
  62 pam_sm_acct_mgmt(pam_handle_t *pamh, int flags,
  63     int argc __unused, const char *argv[] __unused)
  64 {
  65         login_cap_t *lc;
  66         struct passwd *pwd;
  67         struct stat st;
  68         int retval, fd;
  69         ssize_t ss;
  70         const char *user, *nologin;
  71         char *mtmp;
  72
  73         retval = pam_get_user(pamh, &user, NULL);
  74         if (retval != PAM_SUCCESS)
  75                 return (retval);
  76
  77         PAM_LOG("Got user: %s", user);
  78
  79         pwd = getpwnam(user);
  80         if (pwd == NULL)
  81                 return (PAM_USER_UNKNOWN);
  82
  83         /*
  84          * login_getpwclass(3) will select the "root" class by default
  85          * if pwd->pw_uid is 0.  That class should have "ignorenologin"
  86          * capability so that super-user can bypass nologin.
  87          */
  88         lc = login_getpwclass(pwd);
  89         if (lc == NULL) {
  90                 PAM_LOG("Unable to get login class for user %s", user);
  91                 return (PAM_SERVICE_ERR);
  92         }
  93
  94         if (login_getcapbool(lc, "ignorenologin", 0)) {
  95                 login_close(lc);
  96                 return (PAM_SUCCESS);
  97         }
  98
  99         nologin = login_getcapstr(lc, "nologin", nologin_def, nologin_def);
 100
 101         fd = open(nologin, O_RDONLY, 0);
 102         if (fd < 0) {
 103                 login_close(lc);
 104                 return (PAM_SUCCESS);
 105         }
 106
 107         PAM_LOG("Opened %s file", nologin);
 108
 109         if (fstat(fd, &st) == 0) {
 110                 mtmp = malloc(st.st_size + 1);
 111                 if (mtmp != NULL) {
 112                         ss = read(fd, mtmp, st.st_size);
 113                         if (ss > 0) {
 114                                 mtmp[ss] = '\0';
 115                                 pam_error(pamh, "%s", mtmp);
 116                         }
 117                         free(mtmp);
 118                 }
 119         }
 120
 121         PAM_VERBOSE_ERROR("Administrator refusing you: %s", nologin);
 122
 123         close(fd);
 124         login_close(lc);
 125
 126         return (PAM_AUTH_ERR);
 127 }
 128
 129 PAM_MODULE_ENTRY("pam_nologin");