usr.bin/at/perm.c

   1 /*      $NetBSD: perm.c,v 1.2 2000/10/04 19:24:59 mjl Exp $     */
   2
   3 /*
   4  * perm.c - check user permission for at(1)
   5  * Copyright (C) 1994  Thomas Koenig
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. The name of the author(s) may not be used to endorse or promote
  13  *    products derived from this software without specific prior written
  14  *    permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27
  28 /* System Headers */
  29
  30 #include <sys/types.h>
  31 #include <errno.h>
  32 #include <pwd.h>
  33 #include <stdbool.h>
  34 #include <stddef.h>
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <string.h>
  38 #include <unistd.h>
  39
  40 /* Local headers */
  41
  42 #include "at.h"
  43 #include "panic.h"
  44 #include "pathnames.h"
  45 #include "privs.h"
  46 #include "perm.h"
  47
  48 /* File scope variables */
  49
  50 #ifndef lint
  51 #if 0
  52 static char rcsid[] = "$OpenBSD: perm.c,v 1.1 1997/03/01 23:40:12 millert Exp $";
  53 #else
  54 __RCSID("$NetBSD: perm.c,v 1.2 2000/10/04 19:24:59 mjl Exp $");
  55 #endif
  56 #endif
  57
  58 /* Local functions */
  59
  60 static bool
  61 check_for_user(FILE *fp, const char *name)
  62 {
  63         char *buffer;
  64         size_t len;
  65         bool found = false;
  66
  67         len = strlen(name);
  68         if ((buffer = malloc(len + 2)) == NULL)
  69                 panic("Insufficient virtual memory");
  70
  71         while (fgets(buffer, (int)len + 2, fp) != NULL) {
  72                 if (strncmp(name, buffer, len) == 0 && buffer[len] == '\n') {
  73                         found = true;
  74                         break;
  75                 }
  76         }
  77         (void)fclose(fp);
  78         free(buffer);
  79         return found;
  80 }
  81
  82 /* Global functions */
  83
  84 bool
  85 check_permission(void)
  86 {
  87         FILE *fp;
  88         uid_t uid = geteuid();
  89         struct passwd *pentry;
  90
  91         if (uid == 0)
  92                 return true;
  93
  94         if ((pentry = getpwuid(uid)) == NULL) {
  95                 perror("Cannot access user database");
  96                 exit(EXIT_FAILURE);
  97         }
  98
  99         PRIV_START;
 100
 101         fp = fopen(_PATH_AT_ALLOW, "r");
 102
 103         PRIV_END;
 104
 105         if (fp != NULL) {
 106                 return check_for_user(fp, pentry->pw_name);
 107         } else {
 108                 PRIV_START;
 109
 110                 fp = fopen(_PATH_AT_DENY, "r");
 111
 112                 PRIV_END;
 113
 114                 if (fp != NULL)
 115                         return !check_for_user(fp, pentry->pw_name);
 116         }
 117         return false;
 118 }