lib/libpam/modules/pam_nologin/pam_nologin.c

   1 /*      $NetBSD: pam_nologin.c,v 1.6 2006/02/15 20:28:32 bouyer Exp $   */
   2
   3 /*-
   4  * Copyright 2001 Mark R V Murray
   5  * All rights reserved.
   6  * Copyright (c) 2001 Networks Associates Technology, Inc.
   7  * All rights reserved.
   8  *
   9  * Portions of this software were developed for the FreeBSD Project by
  10  * ThinkSec AS and NAI Labs, the Security Research Division of Network
  11  * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
  12  * ("CBOSS"), as part of the DARPA CHATS research program.
  13  *
  14  * Redistribution and use in source and binary forms, with or without
  15  * modification, are permitted provided that the following conditions
  16  * are met:
  17  * 1. Redistributions of source code must retain the above copyright
  18  *    notice, this list of conditions and the following disclaimer.
  19  * 2. Redistributions in binary form must reproduce the above copyright
  20  *    notice, this list of conditions and the following disclaimer in the
  21  *    documentation and/or other materials provided with the distribution.
  22  * 3. The name of the author may not be used to endorse or promote
  23  *    products derived from this software without specific prior written
  24  *    permission.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  36  * SUCH DAMAGE.
  37  */
  38
  39 #include <sys/cdefs.h>
  40 #ifdef __FreeBSD__
  41 __FBSDID("$FreeBSD: src/lib/libpam/modules/pam_nologin/pam_nologin.c,v 1.10 2002/04/12 22:27:21 des Exp $");
  42 #else
  43 __RCSID("$NetBSD: pam_nologin.c,v 1.6 2006/02/15 20:28:32 bouyer Exp $");
  44 #endif
  45
  46
  47 #include <sys/types.h>
  48 #include <sys/stat.h>
  49 #include <fcntl.h>
  50 #include <login_cap.h>
  51 #include <pwd.h>
  52 #include <errno.h>
  53 #include <string.h>
  54 #include <stdio.h>
  55 #include <stdlib.h>
  56 #include <unistd.h>
  57
  58 #define PAM_SM_AUTH
  59
  60 #include <security/pam_appl.h>
  61 #include <security/pam_modules.h>
  62 #include <security/pam_mod_misc.h>
  63
  64 #define NOLOGIN "/etc/nologin"
  65
  66 static char nologin_def[] = NOLOGIN;
  67
  68 PAM_EXTERN int
  69 pam_sm_authenticate(pam_handle_t *pamh, int flags __unused,
  70     int argc __unused, const char *argv[] __unused)
  71 {
  72         login_cap_t *lc;
  73         struct passwd *pwd, pwres;
  74         struct stat st;
  75         int retval, fd;
  76         int ignorenologin = 0;
  77         int rootlogin = 0;
  78         const char *user, *nologin;
  79         char *mtmp;
  80         char pwbuf[1024];
  81
  82         if ((retval = pam_get_user(pamh, &user, NULL)) != PAM_SUCCESS)
  83                 return retval;
  84
  85         PAM_LOG("Got user: %s", user);
  86
  87         /*
  88          * For root, the default is to ignore nologin, but the
  89          * ignorenologin capability can override this, so we
  90          * set the default appropriately.
  91          *
  92          * Do not allow login of unexisting users, so that a directory
  93          * failure will not cause the nologin capability to be ignored.
  94          */
  95         if (getpwnam_r(user, &pwres, pwbuf, sizeof(pwbuf), &pwd) != 0 ||
  96             pwd == NULL) {
  97                 return PAM_USER_UNKNOWN;
  98         } else {
  99                 if (pwd->pw_uid == 0)
 100                         rootlogin = 1;
 101         }
 102
 103         lc = login_getclass(pwd->pw_class);
 104         ignorenologin = login_getcapbool(lc, "ignorenologin", rootlogin);
 105         nologin = login_getcapstr(lc, "nologin", nologin_def, nologin_def);
 106         login_close(lc);
 107         lc = NULL;
 108
 109         if (ignorenologin)
 110                 return PAM_SUCCESS;
 111
 112         if ((fd = open(nologin, O_RDONLY, 0)) == -1) {
 113                 /*
 114                  * The file does not exist, login is granted
 115                  */
 116                 if (errno == ENOENT)
 117                         return PAM_SUCCESS;
 118
 119                 /*
 120                  * open failed, but the file exists. This could be
 121                  * a temporary problem (system resources exausted):
 122                  * Refuse the login.
 123                  */
 124                 PAM_LOG("Cannot open %s file: %s", nologin, strerror(errno));
 125                 return PAM_AUTH_ERR;
 126         }
 127
 128         PAM_LOG("Opened %s file", nologin);
 129
 130         if (fstat(fd, &st) < 0)
 131                 return PAM_AUTH_ERR;
 132
 133         mtmp = malloc(st.st_size + 1);
 134         if (mtmp != NULL) {
 135                 read(fd, mtmp, st.st_size);
 136                 mtmp[st.st_size] = '\0';
 137                 pam_error(pamh, "%s", mtmp);
 138                 free(mtmp);
 139         }
 140
 141         PAM_VERBOSE_ERROR("Administrator refusing you: %s", nologin);
 142
 143         return PAM_AUTH_ERR;
 144 }
 145
 146 PAM_EXTERN int
 147 pam_sm_setcred(pam_handle_t *pamh __unused, int flags __unused,
 148     int argc __unused, const char *argv[] __unused)
 149 {
 150
 151         return (PAM_SUCCESS);
 152 }
 153
 154 PAM_MODULE_ENTRY("pam_nologin");