zebra/ipforward_proc.c

   1 /*
   2  * Fetch ipforward value by reading /proc filesystem.
   3  * Copyright (C) 1997 Kunihiro Ishiguro
   4  *
   5  * This file is part of GNU Zebra.
   6  *
   7  * GNU Zebra is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License as published by the
   9  * Free Software Foundation; either version 2, or (at your option) any
  10  * later version.
  11  *
  12  * GNU Zebra is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License along
  18  * with this program; see the file COPYING; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #include <zebra.h>
  23
  24 #ifdef GNU_LINUX
  25
  26 #include "log.h"
  27 #include "privs.h"
  28
  29 #include "zebra/ipforward.h"
  30
  31 extern struct zebra_privs_t zserv_privs;
  32
  33 char proc_net_snmp[] = "/proc/net/snmp";
  34
  35 static void dropline(FILE *fp)
  36 {
  37         int c;
  38
  39         while ((c = getc(fp)) != '\n')
  40                 ;
  41 }
  42
  43 int ipforward(void)
  44 {
  45         int ret = 0;
  46         FILE *fp;
  47         int ipforwarding = 0;
  48         char buf[10];
  49
  50         fp = fopen(proc_net_snmp, "r");
  51
  52         if (fp == NULL)
  53                 return -1;
  54
  55         /* We don't care about the first line. */
  56         dropline(fp);
  57
  58         /* Get ip_statistics.IpForwarding :
  59            1 => ip forwarding enabled
  60            2 => ip forwarding off. */
  61         if (fgets(buf, 6, fp))
  62                 ret = sscanf(buf, "Ip: %d", &ipforwarding);
  63
  64         fclose(fp);
  65
  66         if (ret == 1 && ipforwarding == 1)
  67                 return 1;
  68
  69         return 0;
  70 }
  71
  72 /* char proc_ipv4_forwarding[] = "/proc/sys/net/ipv4/conf/all/forwarding"; */
  73 char proc_ipv4_forwarding[] = "/proc/sys/net/ipv4/ip_forward";
  74
  75 int ipforward_on(void)
  76 {
  77         FILE *fp;
  78
  79         if (zserv_privs.change(ZPRIVS_RAISE))
  80                 zlog_err("Can't raise privileges, %s", safe_strerror(errno));
  81
  82         fp = fopen(proc_ipv4_forwarding, "w");
  83
  84         if (fp == NULL) {
  85                 if (zserv_privs.change(ZPRIVS_LOWER))
  86                         zlog_err("Can't lower privileges, %s",
  87                                  safe_strerror(errno));
  88                 return -1;
  89         }
  90
  91         fprintf(fp, "1\n");
  92
  93         fclose(fp);
  94
  95         if (zserv_privs.change(ZPRIVS_LOWER))
  96                 zlog_err("Can't lower privileges, %s", safe_strerror(errno));
  97
  98         return ipforward();
  99 }
 100
 101 int ipforward_off(void)
 102 {
 103         FILE *fp;
 104
 105         if (zserv_privs.change(ZPRIVS_RAISE))
 106                 zlog_err("Can't raise privileges, %s", safe_strerror(errno));
 107
 108         fp = fopen(proc_ipv4_forwarding, "w");
 109
 110         if (fp == NULL) {
 111                 if (zserv_privs.change(ZPRIVS_LOWER))
 112                         zlog_err("Can't lower privileges, %s",
 113                                  safe_strerror(errno));
 114                 return -1;
 115         }
 116
 117         fprintf(fp, "0\n");
 118
 119         fclose(fp);
 120
 121         if (zserv_privs.change(ZPRIVS_LOWER))
 122                 zlog_err("Can't lower privileges, %s", safe_strerror(errno));
 123
 124         return ipforward();
 125 }
 126
 127 char proc_ipv6_forwarding[] = "/proc/sys/net/ipv6/conf/all/forwarding";
 128
 129 int ipforward_ipv6(void)
 130 {
 131         int ret = 0;
 132         FILE *fp;
 133         char buf[5];
 134         int ipforwarding = 0;
 135
 136         fp = fopen(proc_ipv6_forwarding, "r");
 137
 138         if (fp == NULL)
 139                 return -1;
 140
 141         if (fgets(buf, 2, fp))
 142                 ret = sscanf(buf, "%d", &ipforwarding);
 143
 144         fclose(fp);
 145
 146         if (ret != 1)
 147                 return 0;
 148
 149         return ipforwarding;
 150 }
 151
 152 int ipforward_ipv6_on(void)
 153 {
 154         FILE *fp;
 155
 156         if (zserv_privs.change(ZPRIVS_RAISE))
 157                 zlog_err("Can't raise privileges, %s", safe_strerror(errno));
 158
 159         fp = fopen(proc_ipv6_forwarding, "w");
 160
 161         if (fp == NULL) {
 162                 if (zserv_privs.change(ZPRIVS_LOWER))
 163                         zlog_err("Can't lower privileges, %s",
 164                                  safe_strerror(errno));
 165                 return -1;
 166         }
 167
 168         fprintf(fp, "1\n");
 169
 170         fclose(fp);
 171
 172         if (zserv_privs.change(ZPRIVS_LOWER))
 173                 zlog_err("Can't lower privileges, %s", safe_strerror(errno));
 174
 175         return ipforward_ipv6();
 176 }
 177
 178
 179 int ipforward_ipv6_off(void)
 180 {
 181         FILE *fp;
 182
 183         if (zserv_privs.change(ZPRIVS_RAISE))
 184                 zlog_err("Can't raise privileges, %s", safe_strerror(errno));
 185
 186         fp = fopen(proc_ipv6_forwarding, "w");
 187
 188         if (fp == NULL) {
 189                 if (zserv_privs.change(ZPRIVS_LOWER))
 190                         zlog_err("Can't lower privileges, %s",
 191                                  safe_strerror(errno));
 192                 return -1;
 193         }
 194
 195         fprintf(fp, "0\n");
 196
 197         fclose(fp);
 198
 199         if (zserv_privs.change(ZPRIVS_LOWER))
 200                 zlog_err("Can't lower privileges, %s", safe_strerror(errno));
 201
 202         return ipforward_ipv6();
 203 }
 204
 205 #endif /* GNU_LINUX */