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

   1 /* -*-c-*-
   2  *
   3  * $Id: acl.c,v 1.4 2003/11/25 14:08:23 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 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: acl.c,v $
  32  * Revision 1.4  2003/11/25 14:08:23  mdw
  33  * Debianization.  Socket target options.  Internet binding.
  34  *
  35  * Revision 1.3  1999/07/27 18:30:53  mdw
  36  * Various minor portability fixes.
  37  *
  38  * Revision 1.2  1999/07/26 23:28:15  mdw
  39  * Minor modifications for new design.
  40  *
  41  * Revision 1.1.1.1  1999/07/01 08:56:23  mdw
  42  * Initial revision.
  43  *
  44  */
  45
  46 /*----- Header files ------------------------------------------------------*/
  47
  48 #include "config.h"
  49
  50 #include <errno.h>
  51 #include <stdio.h>
  52 #include <stdlib.h>
  53 #include <string.h>
  54
  55 #include <sys/types.h>
  56 #include <unistd.h>
  57
  58 #include <sys/socket.h>
  59 #include <netinet/in.h>
  60 #include <arpa/inet.h>
  61 #include <netdb.h>
  62
  63 #include <mLib/sub.h>
  64
  65 #include "acl.h"
  66
  67 /*----- Main code ---------------------------------------------------------*/
  68
  69 /* --- @acl_addhost@ --- *
  70  *
  71  * Arguments:   @acl_entry ***a@ = address of pointer to list tail
  72  *              @unsigned act@ = what to do with matching addresses
  73  *              @struct in_addr addr, mask@ = address and mask to match
  74  *
  75  * Returns:     ---
  76  *
  77  * Use:         Adds a host-authentication entry to the end of an access
  78  *              control list.
  79  */
  80
  81 static int acl_checkhost(void *aa, struct in_addr addr, unsigned port)
  82 {
  83   acl_host *a = aa;
  84   return ((addr.s_addr & a->mask.s_addr) == a->addr.s_addr);
  85 }
  86
  87 static void acl_dumphost(void *aa, FILE *fp)
  88 {
  89   acl_host *a = aa;
  90
  91   fputs("from ", fp);
  92   fputs(inet_ntoa(a->addr), fp);
  93   fputc('/', fp);
  94   fputs(inet_ntoa(a->mask), fp);
  95 }
  96
  97 static void acl_freehost(void *aa)
  98 {
  99   acl_host *a = aa;
 100   DESTROY(a);
 101 }
 102
 103 static const acl_ops acl_hostops = {
 104   acl_checkhost, acl_dumphost, acl_freehost
 105 };
 106
 107 void acl_addhost(acl_entry ***a, unsigned act,
 108                  struct in_addr addr, struct in_addr mask)
 109 {
 110   acl_host *aa = CREATE(acl_host);
 111   aa->a.next = 0;
 112   aa->a.ops = &acl_hostops;
 113   aa->a.act = act;
 114   aa->addr.s_addr = addr.s_addr & mask.s_addr;
 115   aa->mask = mask;
 116   **a = &aa->a;
 117   *a = &aa->a.next;
 118 }
 119
 120 /* --- @acl_addpriv@ --- *
 121  *
 122  * Arguments:   @acl_entry ***a@ = address of pointer to list tail
 123  *              @unsigned act@ = what to do with matching addresses
 124  *
 125  * Returns:     ---
 126  *
 127  * Use:         Adds a privileged-port check to the end of an access control
 128  *              list.
 129  */
 130
 131 static int acl_checkpriv(void *aa, struct in_addr addr, unsigned port)
 132 {
 133   return (port < 1024);
 134 }
 135
 136 static void acl_dumppriv(void *aa, FILE *fp)
 137 {
 138   fputs("from privileged ports", fp);
 139 }
 140
 141 static void acl_freepriv(void *aa)
 142 {
 143   acl_entry *a = aa;
 144   DESTROY(a);
 145 }
 146
 147 static const acl_ops acl_privops = {
 148   acl_checkpriv, acl_dumppriv, acl_freepriv
 149 };
 150
 151 void acl_addpriv(acl_entry ***a, unsigned act)
 152 {
 153   acl_entry *aa = CREATE(acl_entry);
 154   aa->next = 0;
 155   aa->ops = &acl_privops;
 156   aa->act = act;
 157   **a = aa;
 158   *a = &aa->next;
 159 }
 160
 161 /* --- @acl_check@ --- *
 162  *
 163  * Arguments:   @acl_entry *a@ = pointer to ACL to check against
 164  *              @struct in_addr addr@ = address to check
 165  *              @unsigned port@ = port number to check
 166  *              @int *act@ = verdict (should initially be @ACT_ALLOW@)
 167  *
 168  * Returns:     Zero if undecided, nonzero if a rule matched.
 169  *
 170  * Use:         Checks an address against an ACL.
 171  */
 172
 173 int acl_check(acl_entry *a, struct in_addr addr, unsigned port, int *act)
 174 {
 175   for (; a; a = a->next) {
 176     if (a->ops->check(a, addr, port)) {
 177       *act = a->act & ACL_PERM;
 178       return (1);
 179     }
 180     *act = (a->act & ACL_PERM) ^ 1;
 181   }
 182   return (0);
 183 }
 184
 185 /* --- @acl_dump@ --- *
 186  *
 187  * Arguments:   @acl_entry *a@ = pointer to ACL to dump
 188  *              @FILE *fp@ = pointer to stream to dump on
 189  *
 190  * Returns:     ---
 191  *
 192  * Use:         Dumps an access control list to an output stream.
 193  */
 194
 195 void acl_dump(acl_entry *a, FILE *fp)
 196 {
 197   for (; a; a = a->next) {
 198     fprintf(fp, "  %s ",
 199             (a->act & ACL_PERM) == ACL_ALLOW ? "allow" : "deny");
 200     a->ops->dump(a, fp);
 201     fputc('\n', fp);
 202   }
 203 }
 204
 205 /* --- @acl_free@ --- *
 206  *
 207  * Arguments:   @acl_entry *a@ = pointer to a list of ACLs
 208  *
 209  * Returns:     ---
 210  *
 211  * Use:         Frees all of the memory used by an ACL.
 212  */
 213
 214 void acl_free(acl_entry *a)
 215 {
 216   while (a) {
 217     acl_entry *aa = a;
 218     a = a->next;
 219     aa->ops->free(aa);
 220   }
 221 }
 222
 223 /*----- That's all, folks -------------------------------------------------*/