at.tproj/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
  26 #include <sys/cdefs.h>
  27 __FBSDID("$FreeBSD: src/usr.bin/at/perm.c,v 1.13 2001/12/10 21:13:01 dwmalone Exp $");
  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 check_for_user(FILE *fp,const char *name)
  60 {
  61     char *buffer;
  62     size_t len;
  63     int found = 0;
  64
  65     len = strlen(name);
  66     if ((buffer = malloc(len+2)) == NULL)
  67         errx(EXIT_FAILURE, "virtual memory exhausted");
  68
  69     while(fgets(buffer, len+2, fp) != NULL)
  70     {
  71         if ((strncmp(name, buffer, len) == 0) &&
  72             (buffer[len] == '\n'))
  73         {
  74             found = 1;
  75             break;
  76         }
  77     }
  78     fclose(fp);
  79     free(buffer);
  80     return found;
  81 }
  82 /* Global functions */
  83 int check_permission(void)
  84 {
  85     FILE *fp;
  86     uid_t uid = geteuid();
  87     struct passwd *pentry;
  88
  89     if (uid==0)
  90         return 1;
  91
  92     if ((pentry = getpwuid(uid)) == NULL)
  93         err(EXIT_FAILURE, "cannot access user database");
  94
  95     PRIV_START
  96
  97     fp=fopen(PERM_PATH "at.allow","r");
  98
  99     PRIV_END
 100
 101     if (fp != NULL)
 102     {
 103         return check_for_user(fp, pentry->pw_name);
 104     }
 105     else if (errno == ENOENT)
 106     {
 107
 108         PRIV_START
 109
 110         fp=fopen(PERM_PATH "at.deny", "r");
 111
 112         PRIV_END
 113
 114         if (fp != NULL)
 115         {
 116             return !check_for_user(fp, pentry->pw_name);
 117         }
 118         else if (errno != ENOENT)
 119             warn("at.deny");
 120     }
 121     else
 122         warn("at.allow");
 123     return 0;
 124 }