kernel/linux/net/ipv4/netfilter/ip_conntrack_proto_icmp.c

   1 /* (C) 1999-2001 Paul `Rusty' Russell
   2  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/sched.h>
  11 #include <linux/timer.h>
  12 #include <linux/netfilter.h>
  13 #include <linux/in.h>
  14 #include <linux/icmp.h>
  15 #include <linux/netfilter_ipv4/ip_conntrack_protocol.h>
  16
  17 #ifdef CONFIG_MIPS_BRCM
  18 unsigned long ip_ct_icmp_timeout = 4*HZ;
  19 #else
  20 unsigned long ip_ct_icmp_timeout = 30*HZ;
  21 #endif
  22
  23 #if 0
  24 #define DEBUGP printk
  25 #else
  26 #define DEBUGP(format, args...)
  27 #endif
  28
  29 static int icmp_pkt_to_tuple(const struct sk_buff *skb,
  30                              unsigned int dataoff,
  31                              struct ip_conntrack_tuple *tuple)
  32 {
  33         struct icmphdr hdr;
  34
  35         if (skb_copy_bits(skb, dataoff, &hdr, sizeof(hdr)) != 0)
  36                 return 0;
  37
  38         tuple->dst.u.icmp.type = hdr.type;
  39         tuple->src.u.icmp.id = hdr.un.echo.id;
  40         tuple->dst.u.icmp.code = hdr.code;
  41
  42         return 1;
  43 }
  44
  45 static int icmp_invert_tuple(struct ip_conntrack_tuple *tuple,
  46                              const struct ip_conntrack_tuple *orig)
  47 {
  48         /* Add 1; spaces filled with 0. */
  49         static u_int8_t invmap[]
  50                 = { [ICMP_ECHO] = ICMP_ECHOREPLY + 1,
  51                     [ICMP_ECHOREPLY] = ICMP_ECHO + 1,
  52                     [ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1,
  53                     [ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1,
  54                     [ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1,
  55                     [ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1,
  56                     [ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1,
  57                     [ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1};
  58
  59         if (orig->dst.u.icmp.type >= sizeof(invmap)
  60             || !invmap[orig->dst.u.icmp.type])
  61                 return 0;
  62
  63         tuple->src.u.icmp.id = orig->src.u.icmp.id;
  64         tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1;
  65         tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
  66         return 1;
  67 }
  68
  69 /* Print out the per-protocol part of the tuple. */
  70 static unsigned int icmp_print_tuple(char *buffer,
  71                                      const struct ip_conntrack_tuple *tuple)
  72 {
  73         return sprintf(buffer, "type=%u code=%u id=%u ",
  74                        tuple->dst.u.icmp.type,
  75                        tuple->dst.u.icmp.code,
  76                        ntohs(tuple->src.u.icmp.id));
  77 }
  78
  79 /* Print out the private part of the conntrack. */
  80 static unsigned int icmp_print_conntrack(char *buffer,
  81                                      const struct ip_conntrack *conntrack)
  82 {
  83         return 0;
  84 }
  85
  86 /* Returns verdict for packet, or -1 for invalid. */
  87 static int icmp_packet(struct ip_conntrack *ct,
  88                        const struct sk_buff *skb,
  89                        enum ip_conntrack_info ctinfo)
  90 {
  91         /* Try to delete connection immediately after all replies:
  92            won't actually vanish as we still have skb, and del_timer
  93            means this will only run once even if count hits zero twice
  94            (theoretically possible with SMP) */
  95         if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
  96                 if (atomic_dec_and_test(&ct->proto.icmp.count)
  97                     && del_timer(&ct->timeout))
  98                         ct->timeout.function((unsigned long)ct);
  99         } else {
 100                 atomic_inc(&ct->proto.icmp.count);
 101                 ip_ct_refresh(ct, ip_ct_icmp_timeout);
 102         }
 103
 104         return NF_ACCEPT;
 105 }
 106
 107 #ifdef CONFIG_MIPS_BRCM
 108 extern int ip_conntrack_max;
 109 #endif
 110 /* Called when a new connection for this protocol found. */
 111 static int icmp_new(struct ip_conntrack *conntrack,
 112                     const struct sk_buff *skb)
 113 {
 114         static u_int8_t valid_new[]
 115                 = { [ICMP_ECHO] = 1,
 116                     [ICMP_TIMESTAMP] = 1,
 117                     [ICMP_INFO_REQUEST] = 1,
 118                     [ICMP_ADDRESS] = 1 };
 119 #ifdef CONFIG_MIPS_BRCM
 120         if ( ip_conntrack_max == 0)
 121                 return NF_DROP;
 122 #endif
 123
 124
 125         if (conntrack->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new)
 126             || !valid_new[conntrack->tuplehash[0].tuple.dst.u.icmp.type]) {
 127                 /* Can't create a new ICMP `conn' with this. */
 128                 DEBUGP("icmp: can't create new conn with type %u\n",
 129                        conntrack->tuplehash[0].tuple.dst.u.icmp.type);
 130                 DUMP_TUPLE(&conntrack->tuplehash[0].tuple);
 131                 return 0;
 132         }
 133         atomic_set(&conntrack->proto.icmp.count, 0);
 134         return 1;
 135 }
 136
 137 struct ip_conntrack_protocol ip_conntrack_protocol_icmp
 138 = { { NULL, NULL }, IPPROTO_ICMP, "icmp",
 139     icmp_pkt_to_tuple, icmp_invert_tuple, icmp_print_tuple,
 140     icmp_print_conntrack, icmp_packet, icmp_new, NULL, NULL, NULL };