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

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