usr.bin/at/perm.c

   1 /*
   2  *  perm.c - check user permission for at(1)
   3  *  Copyright (C) 1994  Thomas Koenig
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. The name of the author(s) may not be used to endorse or promote
  11  *    products derived from this software without specific prior written
  12  *    permission.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
  15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  17  * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
  18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  21  * THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  *
  25  * $FreeBSD: src/usr.bin/at/perm.c,v 1.11 2001/12/02 12:26:18 markm Exp $
  26  * $DragonFly: src/usr.bin/at/perm.c,v 1.5 2007/08/26 16:12:27 pavalos Exp $
  27  */
  28
  29 /* System Headers */
  30
  31 #include <sys/types.h>
  32 #include <err.h>
  33 #include <errno.h>
  34 #include <pwd.h>
  35 #include <stddef.h>
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38 #include <string.h>
  39 #include <unistd.h>
  40
  41 /* Local headers */
  42
  43 #include "at.h"
  44 #include "perm.h"
  45 #include "privs.h"
  46
  47 /* Macros */
  48
  49 #define MAXUSERID 10
  50
  51 /* Structures and unions */
  52
  53 /* Function declarations */
  54
  55 static int check_for_user(FILE *fp, const char *name);
  56
  57 /* Local functions */
  58
  59 static int
  60 check_for_user(FILE *fp, const char *name)
  61 {
  62     char *buffer;
  63     size_t len;
  64     int found = 0;
  65
  66     len = strlen(name);
  67     if ((buffer = malloc(len+2)) == NULL)
  68         errx(EXIT_FAILURE, "virtual memory exhausted");
  69
  70     while(fgets(buffer, len+2, fp) != NULL)
  71     {
  72         if ((strncmp(name, buffer, len) == 0) &&
  73             (buffer[len] == '\n'))
  74         {
  75             found = 1;
  76             break;
  77         }
  78     }
  79     fclose(fp);
  80     free(buffer);
  81     return found;
  82 }
  83
  84 /* Global functions */
  85 int
  86 check_permission(void)
  87 {
  88     FILE *fp;
  89     uid_t uid = geteuid();
  90     struct passwd *pentry;
  91
  92     if (uid==0)
  93         return 1;
  94
  95     if ((pentry = getpwuid(uid)) == NULL)
  96         err(EXIT_FAILURE, "cannot access user database");
  97
  98     PRIV_START
  99
 100     fp = fopen(PERM_PATH "at.allow","r");
 101
 102     PRIV_END
 103
 104     if (fp != NULL)
 105     {
 106         return check_for_user(fp, pentry->pw_name);
 107     }
 108     else if (errno == ENOENT)
 109     {
 110
 111         PRIV_START
 112
 113         fp = fopen(PERM_PATH "at.deny", "r");
 114
 115         PRIV_END
 116
 117         if (fp != NULL)
 118         {
 119             return !check_for_user(fp, pentry->pw_name);
 120         }
 121         else if (errno != ENOENT)
 122             warn("at.deny");
 123     }
 124     else
 125         warn("at.allow");
 126     return 0;
 127 }