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 "panic.h"
  45 #include "perm.h"
  46 #include "privs.h"
  47
  48 /* Macros */
  49
  50 #define MAXUSERID 10
  51
  52 /* Structures and unions */
  53
  54 /* Function declarations */
  55
  56 static int check_for_user(FILE *fp,const char *name);
  57
  58 /* Local functions */
  59
  60 static int check_for_user(FILE *fp,const char *name)
  61 {
  62     char *buffer;
  63     int len;
  64     int found = 0;
  65
  66     len = (int)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 /* Global functions */
  84 int check_permission(void)
  85 {
  86     FILE *fp;
  87     uid_t uid = geteuid();
  88     struct passwd *pentry;
  89
  90     if (uid==0)
  91         return 1;
  92
  93     if ((pentry = getpwuid(uid)) == NULL)
  94         err(EXIT_FAILURE, "cannot access user database");
  95
  96     PRIV_START
  97
  98     fp=fopen(PERM_PATH "at.allow","r");
  99
 100     PRIV_END
 101
 102     if (fp != NULL)
 103     {
 104         return check_for_user(fp, pentry->pw_name);
 105     }
 106     else if (errno == ENOENT)
 107     {
 108
 109         PRIV_START
 110
 111         fp=fopen(PERM_PATH "at.deny", "r");
 112
 113         PRIV_END
 114
 115         if (fp != NULL)
 116         {
 117             return !check_for_user(fp, pentry->pw_name);
 118         }
 119         else if (errno != ENOENT)
 120             warn("at.deny");
 121     }
 122     else
 123         warn("at.allow");
 124     return 0;
 125 }