net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c

   1 /*
   2  * Copyright (C)2003,2004 USAGI/WIDE Project
   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  * Author:
   9  *      Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
  10  */
  11
  12 #include <linux/types.h>
  13 #include <linux/timer.h>
  14 #include <linux/module.h>
  15 #include <linux/netfilter.h>
  16 #include <linux/in6.h>
  17 #include <linux/icmpv6.h>
  18 #include <linux/ipv6.h>
  19 #include <net/ipv6.h>
  20 #include <net/ip6_checksum.h>
  21 #include <linux/seq_file.h>
  22 #include <linux/netfilter_ipv6.h>
  23 #include <net/netfilter/nf_conntrack_tuple.h>
  24 #include <net/netfilter/nf_conntrack_l4proto.h>
  25 #include <net/netfilter/nf_conntrack_core.h>
  26 #include <net/netfilter/ipv6/nf_conntrack_icmpv6.h>
  27
  28 static unsigned long nf_ct_icmpv6_timeout __read_mostly = 30*HZ;
  29
  30 static int icmpv6_pkt_to_tuple(const struct sk_buff *skb,
  31                                unsigned int dataoff,
  32                                struct nf_conntrack_tuple *tuple)
  33 {
  34         struct icmp6hdr _hdr, *hp;
  35
  36         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  37         if (hp == NULL)
  38                 return 0;
  39         tuple->dst.u.icmp.type = hp->icmp6_type;
  40         tuple->src.u.icmp.id = hp->icmp6_identifier;
  41         tuple->dst.u.icmp.code = hp->icmp6_code;
  42
  43         return 1;
  44 }
  45
  46 /* Add 1; spaces filled with 0. */
  47 static u_int8_t invmap[] = {
  48         [ICMPV6_ECHO_REQUEST - 128]     = ICMPV6_ECHO_REPLY + 1,
  49         [ICMPV6_ECHO_REPLY - 128]       = ICMPV6_ECHO_REQUEST + 1,
  50         [ICMPV6_NI_QUERY - 128]         = ICMPV6_NI_QUERY + 1,
  51         [ICMPV6_NI_REPLY - 128]         = ICMPV6_NI_REPLY +1
  52 };
  53
  54 static int icmpv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  55                                const struct nf_conntrack_tuple *orig)
  56 {
  57         int type = orig->dst.u.icmp.type - 128;
  58         if (type < 0 || type >= sizeof(invmap) || !invmap[type])
  59                 return 0;
  60
  61         tuple->src.u.icmp.id   = orig->src.u.icmp.id;
  62         tuple->dst.u.icmp.type = invmap[type] - 1;
  63         tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
  64         return 1;
  65 }
  66
  67 /* Print out the per-protocol part of the tuple. */
  68 static int icmpv6_print_tuple(struct seq_file *s,
  69                               const struct nf_conntrack_tuple *tuple)
  70 {
  71         return seq_printf(s, "type=%u code=%u id=%u ",
  72                           tuple->dst.u.icmp.type,
  73                           tuple->dst.u.icmp.code,
  74                           ntohs(tuple->src.u.icmp.id));
  75 }
  76
  77 /* Print out the private part of the conntrack. */
  78 static int icmpv6_print_conntrack(struct seq_file *s,
  79                                   const struct nf_conn *conntrack)
  80 {
  81         return 0;
  82 }
  83
  84 /* Returns verdict for packet, or -1 for invalid. */
  85 static int icmpv6_packet(struct nf_conn *ct,
  86                        const struct sk_buff *skb,
  87                        unsigned int dataoff,
  88                        enum ip_conntrack_info ctinfo,
  89                        int pf,
  90                        unsigned int hooknum)
  91 {
  92         /* Try to delete connection immediately after all replies:
  93            won't actually vanish as we still have skb, and del_timer
  94            means this will only run once even if count hits zero twice
  95            (theoretically possible with SMP) */
  96         if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
  97                 if (atomic_dec_and_test(&ct->proto.icmp.count)
  98                     && del_timer(&ct->timeout))
  99                         ct->timeout.function((unsigned long)ct);
 100         } else {
 101                 atomic_inc(&ct->proto.icmp.count);
 102                 nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);
 103                 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmpv6_timeout);
 104         }
 105
 106         return NF_ACCEPT;
 107 }
 108
 109 /* Called when a new connection for this protocol found. */
 110 static int icmpv6_new(struct nf_conn *conntrack,
 111                       const struct sk_buff *skb,
 112                       unsigned int dataoff)
 113 {
 114         static u_int8_t valid_new[] = {
 115                 [ICMPV6_ECHO_REQUEST - 128] = 1,
 116                 [ICMPV6_NI_QUERY - 128] = 1
 117         };
 118         int type = conntrack->tuplehash[0].tuple.dst.u.icmp.type - 128;
 119
 120         if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
 121                 /* Can't create a new ICMPv6 `conn' with this. */
 122                 pr_debug("icmpv6: can't create new conn with type %u\n",
 123                          type + 128);
 124                 NF_CT_DUMP_TUPLE(&conntrack->tuplehash[0].tuple);
 125                 return 0;
 126         }
 127         atomic_set(&conntrack->proto.icmp.count, 0);
 128         return 1;
 129 }
 130
 131 static int
 132 icmpv6_error_message(struct sk_buff *skb,
 133                      unsigned int icmp6off,
 134                      enum ip_conntrack_info *ctinfo,
 135                      unsigned int hooknum)
 136 {
 137         struct nf_conntrack_tuple intuple, origtuple;
 138         struct nf_conntrack_tuple_hash *h;
 139         struct nf_conntrack_l4proto *inproto;
 140
 141         NF_CT_ASSERT(skb->nfct == NULL);
 142
 143         /* Are they talking about one of our connections? */
 144         if (!nf_ct_get_tuplepr(skb,
 145                                skb_network_offset(skb)
 146                                 + sizeof(struct ipv6hdr)
 147                                 + sizeof(struct icmp6hdr),
 148                                PF_INET6, &origtuple)) {
 149                 pr_debug("icmpv6_error: Can't get tuple\n");
 150                 return -NF_ACCEPT;
 151         }
 152
 153         /* rcu_read_lock()ed by nf_hook_slow */
 154         inproto = __nf_ct_l4proto_find(PF_INET6, origtuple.dst.protonum);
 155
 156         /* Ordinarily, we'd expect the inverted tupleproto, but it's
 157            been preserved inside the ICMP. */
 158         if (!nf_ct_invert_tuple(&intuple, &origtuple,
 159                                 &nf_conntrack_l3proto_ipv6, inproto)) {
 160                 pr_debug("icmpv6_error: Can't invert tuple\n");
 161                 return -NF_ACCEPT;
 162         }
 163
 164         *ctinfo = IP_CT_RELATED;
 165
 166         h = nf_conntrack_find_get(&intuple);
 167         if (!h) {
 168                 pr_debug("icmpv6_error: no match\n");
 169                 return -NF_ACCEPT;
 170         } else {
 171                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
 172                         *ctinfo += IP_CT_IS_REPLY;
 173         }
 174
 175         /* Update skb to refer to this connection */
 176         skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
 177         skb->nfctinfo = *ctinfo;
 178         return -NF_ACCEPT;
 179 }
 180
 181 static int
 182 icmpv6_error(struct sk_buff *skb, unsigned int dataoff,
 183              enum ip_conntrack_info *ctinfo, int pf, unsigned int hooknum)
 184 {
 185         struct icmp6hdr _ih, *icmp6h;
 186
 187         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 188         if (icmp6h == NULL) {
 189                 if (LOG_INVALID(IPPROTO_ICMPV6))
 190                 nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 191                               "nf_ct_icmpv6: short packet ");
 192                 return -NF_ACCEPT;
 193         }
 194
 195         if (nf_conntrack_checksum && hooknum == NF_IP6_PRE_ROUTING &&
 196             nf_ip6_checksum(skb, hooknum, dataoff, IPPROTO_ICMPV6)) {
 197                 nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 198                               "nf_ct_icmpv6: ICMPv6 checksum failed\n");
 199                 return -NF_ACCEPT;
 200         }
 201
 202         /* is not error message ? */
 203         if (icmp6h->icmp6_type >= 128)
 204                 return NF_ACCEPT;
 205
 206         return icmpv6_error_message(skb, dataoff, ctinfo, hooknum);
 207 }
 208
 209 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 210
 211 #include <linux/netfilter/nfnetlink.h>
 212 #include <linux/netfilter/nfnetlink_conntrack.h>
 213 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
 214                                   const struct nf_conntrack_tuple *t)
 215 {
 216         NLA_PUT(skb, CTA_PROTO_ICMPV6_ID, sizeof(u_int16_t),
 217                 &t->src.u.icmp.id);
 218         NLA_PUT(skb, CTA_PROTO_ICMPV6_TYPE, sizeof(u_int8_t),
 219                 &t->dst.u.icmp.type);
 220         NLA_PUT(skb, CTA_PROTO_ICMPV6_CODE, sizeof(u_int8_t),
 221                 &t->dst.u.icmp.code);
 222
 223         return 0;
 224
 225 nla_put_failure:
 226         return -1;
 227 }
 228
 229 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
 230         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
 231         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
 232         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
 233 };
 234
 235 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
 236                                 struct nf_conntrack_tuple *tuple)
 237 {
 238         if (!tb[CTA_PROTO_ICMPV6_TYPE]
 239             || !tb[CTA_PROTO_ICMPV6_CODE]
 240             || !tb[CTA_PROTO_ICMPV6_ID])
 241                 return -EINVAL;
 242
 243         tuple->dst.u.icmp.type =
 244                         *(u_int8_t *)nla_data(tb[CTA_PROTO_ICMPV6_TYPE]);
 245         tuple->dst.u.icmp.code =
 246                         *(u_int8_t *)nla_data(tb[CTA_PROTO_ICMPV6_CODE]);
 247         tuple->src.u.icmp.id =
 248                         *(__be16 *)nla_data(tb[CTA_PROTO_ICMPV6_ID]);
 249
 250         if (tuple->dst.u.icmp.type < 128
 251             || tuple->dst.u.icmp.type - 128 >= sizeof(invmap)
 252             || !invmap[tuple->dst.u.icmp.type - 128])
 253                 return -EINVAL;
 254
 255         return 0;
 256 }
 257 #endif
 258
 259 #ifdef CONFIG_SYSCTL
 260 static struct ctl_table_header *icmpv6_sysctl_header;
 261 static struct ctl_table icmpv6_sysctl_table[] = {
 262         {
 263                 .ctl_name       = NET_NF_CONNTRACK_ICMPV6_TIMEOUT,
 264                 .procname       = "nf_conntrack_icmpv6_timeout",
 265                 .data           = &nf_ct_icmpv6_timeout,
 266                 .maxlen         = sizeof(unsigned int),
 267                 .mode           = 0644,
 268                 .proc_handler   = &proc_dointvec_jiffies,
 269         },
 270         {
 271                 .ctl_name       = 0
 272         }
 273 };
 274 #endif /* CONFIG_SYSCTL */
 275
 276 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 __read_mostly =
 277 {
 278         .l3proto                = PF_INET6,
 279         .l4proto                = IPPROTO_ICMPV6,
 280         .name                   = "icmpv6",
 281         .pkt_to_tuple           = icmpv6_pkt_to_tuple,
 282         .invert_tuple           = icmpv6_invert_tuple,
 283         .print_tuple            = icmpv6_print_tuple,
 284         .print_conntrack        = icmpv6_print_conntrack,
 285         .packet                 = icmpv6_packet,
 286         .new                    = icmpv6_new,
 287         .error                  = icmpv6_error,
 288 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 289         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
 290         .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
 291         .nla_policy             = icmpv6_nla_policy,
 292 #endif
 293 #ifdef CONFIG_SYSCTL
 294         .ctl_table_header       = &icmpv6_sysctl_header,
 295         .ctl_table              = icmpv6_sysctl_table,
 296 #endif
 297 };