mdw@git.distorted.org.uk Git - fwd/blob - acl.c

   1 /* -*-c-*-
   2  *
   3  * $Id: acl.c,v 1.5 2004/04/08 01:36:25 mdw Exp $
   4  *
   5  * Access control list handling
   6  *
   7  * (c) 1999 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of the `fw' port forwarder.
  13  *
  14  * `fw' is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * `fw' is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with `fw'; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Header files ------------------------------------------------------*/
  30
  31 #include "config.h"
  32
  33 #include <errno.h>
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <string.h>
  37
  38 #include <sys/types.h>
  39 #include <unistd.h>
  40
  41 #include <sys/socket.h>
  42 #include <netinet/in.h>
  43 #include <arpa/inet.h>
  44 #include <netdb.h>
  45
  46 #include <mLib/sub.h>
  47
  48 #include "acl.h"
  49
  50 /*----- Main code ---------------------------------------------------------*/
  51
  52 /* --- @acl_addhost@ --- *
  53  *
  54  * Arguments:   @acl_entry ***a@ = address of pointer to list tail
  55  *              @unsigned act@ = what to do with matching addresses
  56  *              @struct in_addr addr, mask@ = address and mask to match
  57  *
  58  * Returns:     ---
  59  *
  60  * Use:         Adds a host-authentication entry to the end of an access
  61  *              control list.
  62  */
  63
  64 static int acl_checkhost(void *aa, struct in_addr addr, unsigned port)
  65 {
  66   acl_host *a = aa;
  67   return ((addr.s_addr & a->mask.s_addr) == a->addr.s_addr);
  68 }
  69
  70 static void acl_dumphost(void *aa, FILE *fp)
  71 {
  72   acl_host *a = aa;
  73
  74   fputs("from ", fp);
  75   fputs(inet_ntoa(a->addr), fp);
  76   fputc('/', fp);
  77   fputs(inet_ntoa(a->mask), fp);
  78 }
  79
  80 static void acl_freehost(void *aa)
  81 {
  82   acl_host *a = aa;
  83   DESTROY(a);
  84 }
  85
  86 static const acl_ops acl_hostops = {
  87   acl_checkhost, acl_dumphost, acl_freehost
  88 };
  89
  90 void acl_addhost(acl_entry ***a, unsigned act,
  91                  struct in_addr addr, struct in_addr mask)
  92 {
  93   acl_host *aa = CREATE(acl_host);
  94   aa->a.next = 0;
  95   aa->a.ops = &acl_hostops;
  96   aa->a.act = act;
  97   aa->addr.s_addr = addr.s_addr & mask.s_addr;
  98   aa->mask = mask;
  99   **a = &aa->a;
 100   *a = &aa->a.next;
 101 }
 102
 103 /* --- @acl_addpriv@ --- *
 104  *
 105  * Arguments:   @acl_entry ***a@ = address of pointer to list tail
 106  *              @unsigned act@ = what to do with matching addresses
 107  *
 108  * Returns:     ---
 109  *
 110  * Use:         Adds a privileged-port check to the end of an access control
 111  *              list.
 112  */
 113
 114 static int acl_checkpriv(void *aa, struct in_addr addr, unsigned port)
 115 {
 116   return (port < 1024);
 117 }
 118
 119 static void acl_dumppriv(void *aa, FILE *fp)
 120 {
 121   fputs("from privileged ports", fp);
 122 }
 123
 124 static void acl_freepriv(void *aa)
 125 {
 126   acl_entry *a = aa;
 127   DESTROY(a);
 128 }
 129
 130 static const acl_ops acl_privops = {
 131   acl_checkpriv, acl_dumppriv, acl_freepriv
 132 };
 133
 134 void acl_addpriv(acl_entry ***a, unsigned act)
 135 {
 136   acl_entry *aa = CREATE(acl_entry);
 137   aa->next = 0;
 138   aa->ops = &acl_privops;
 139   aa->act = act;
 140   **a = aa;
 141   *a = &aa->next;
 142 }
 143
 144 /* --- @acl_check@ --- *
 145  *
 146  * Arguments:   @acl_entry *a@ = pointer to ACL to check against
 147  *              @struct in_addr addr@ = address to check
 148  *              @unsigned port@ = port number to check
 149  *              @int *act@ = verdict (should initially be @ACT_ALLOW@)
 150  *
 151  * Returns:     Zero if undecided, nonzero if a rule matched.
 152  *
 153  * Use:         Checks an address against an ACL.
 154  */
 155
 156 int acl_check(acl_entry *a, struct in_addr addr, unsigned port, int *act)
 157 {
 158   for (; a; a = a->next) {
 159     if (a->ops->check(a, addr, port)) {
 160       *act = a->act & ACL_PERM;
 161       return (1);
 162     }
 163     *act = (a->act & ACL_PERM) ^ 1;
 164   }
 165   return (0);
 166 }
 167
 168 /* --- @acl_dump@ --- *
 169  *
 170  * Arguments:   @acl_entry *a@ = pointer to ACL to dump
 171  *              @FILE *fp@ = pointer to stream to dump on
 172  *
 173  * Returns:     ---
 174  *
 175  * Use:         Dumps an access control list to an output stream.
 176  */
 177
 178 void acl_dump(acl_entry *a, FILE *fp)
 179 {
 180   for (; a; a = a->next) {
 181     fprintf(fp, "  %s ",
 182             (a->act & ACL_PERM) == ACL_ALLOW ? "allow" : "deny");
 183     a->ops->dump(a, fp);
 184     fputc('\n', fp);
 185   }
 186 }
 187
 188 /* --- @acl_free@ --- *
 189  *
 190  * Arguments:   @acl_entry *a@ = pointer to a list of ACLs
 191  *
 192  * Returns:     ---
 193  *
 194  * Use:         Frees all of the memory used by an ACL.
 195  */
 196
 197 void acl_free(acl_entry *a)
 198 {
 199   while (a) {
 200     acl_entry *aa = a;
 201     a = a->next;
 202     aa->ops->free(aa);
 203   }
 204 }
 205
 206 /*----- That's all, folks -------------------------------------------------*/