source4/lib/socket/access.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    check access rules for socket connections
   5
   6    Copyright (C) Andrew Tridgell 2004
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22
  23 /*
  24    This module is an adaption of code from the tcpd-1.4 package written
  25    by Wietse Venema, Eindhoven University of Technology, The Netherlands.
  26
  27    The code is used here with permission.
  28
  29    The code has been considerably changed from the original. Bug reports
  30    should be sent to samba-technical@lists.samba.org
  31 */
  32
  33 #include "includes.h"
  34 #include "system/network.h"
  35 #include "lib/socket/socket.h"
  36 #include "lib/util/util_net.h"
  37 #include "lib/util/access.h"
  38
  39 /* return true if the char* contains ip addrs only.  Used to avoid
  40 gethostbyaddr() calls */
  41
  42 static bool only_ipaddrs_in_list(const char** list)
  43 {
  44         bool only_ip = true;
  45
  46         if (!list)
  47                 return true;
  48
  49         for (; *list ; list++) {
  50                 /* factor out the special strings */
  51                 if (strcmp(*list, "ALL")==0 ||
  52                     strcmp(*list, "FAIL")==0 ||
  53                     strcmp(*list, "EXCEPT")==0) {
  54                         continue;
  55                 }
  56
  57                 if (!is_ipaddress(*list)) {
  58                         /*
  59                          * if we failed, make sure that it was not because the token
  60                          * was a network/netmask pair.  Only network/netmask pairs
  61                          * have a '/' in them
  62                          */
  63                         if ((strchr(*list, '/')) == NULL) {
  64                                 only_ip = false;
  65                                 DEBUG(3,("only_ipaddrs_in_list: list has non-ip address (%s)\n", *list));
  66                                 break;
  67                         }
  68                 }
  69         }
  70
  71         return only_ip;
  72 }
  73
  74 /* return true if access should be allowed to a service for a socket */
  75 bool socket_check_access(struct socket_context *sock,
  76                          const char *service_name,
  77                          const char **allow_list, const char **deny_list)
  78 {
  79         bool ret;
  80         const char *name="";
  81         struct socket_address *addr;
  82         TALLOC_CTX *mem_ctx;
  83
  84         if ((!deny_list  || *deny_list==0) &&
  85             (!allow_list || *allow_list==0)) {
  86                 return true;
  87         }
  88
  89         mem_ctx = talloc_init("socket_check_access");
  90         if (!mem_ctx) {
  91                 return false;
  92         }
  93
  94         addr = socket_get_peer_addr(sock, mem_ctx);
  95         if (!addr) {
  96                 DEBUG(0,("socket_check_access: Denied connection from unknown host: could not get peer address from kernel\n"));
  97                 talloc_free(mem_ctx);
  98                 return false;
  99         }
 100
 101         /* bypass gethostbyaddr() calls if the lists only contain IP addrs */
 102         if (!only_ipaddrs_in_list(allow_list) ||
 103             !only_ipaddrs_in_list(deny_list)) {
 104                 name = socket_get_peer_name(sock, mem_ctx);
 105                 if (!name) {
 106                         name = addr->addr;
 107                 }
 108         }
 109
 110         if (!addr) {
 111                 DEBUG(0,("socket_check_access: Denied connection from unknown host\n"));
 112                 talloc_free(mem_ctx);
 113                 return false;
 114         }
 115
 116         ret = allow_access(deny_list, allow_list, name, addr->addr);
 117
 118         if (ret) {
 119                 DEBUG(2,("socket_check_access: Allowed connection to '%s' from %s (%s)\n",
 120                          service_name, name, addr->addr));
 121         } else {
 122                 DEBUG(0,("socket_check_access: Denied connection to '%s' from %s (%s)\n",
 123                          service_name, name, addr->addr));
 124         }
 125
 126         talloc_free(mem_ctx);
 127
 128         return ret;
 129 }