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  * 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
  12  *      - ICMPv6 tracking support. Derived from the original ip_conntrack code
  13  *        net/ipv4/netfilter/ip_conntrack_proto_icmp.c which had the following
  14  *        copyright information:
  15  *              (C) 1999-2001 Paul `Rusty' Russell
  16  *              (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
  17  */
  18
  19 #include <linux/types.h>
  20 #include <linux/sched.h>
  21 #include <linux/timer.h>
  22 #include <linux/module.h>
  23 #include <linux/netfilter.h>
  24 #include <linux/in6.h>
  25 #include <linux/icmpv6.h>
  26 #include <linux/ipv6.h>
  27 #include <net/ipv6.h>
  28 #include <net/ip6_checksum.h>
  29 #include <linux/seq_file.h>
  30 #include <linux/netfilter_ipv6.h>
  31 #include <net/netfilter/nf_conntrack_tuple.h>
  32 #include <net/netfilter/nf_conntrack_protocol.h>
  33 #include <net/netfilter/nf_conntrack_core.h>
  34 #include <net/netfilter/ipv6/nf_conntrack_icmpv6.h>
  35
  36 unsigned long nf_ct_icmpv6_timeout = 30*HZ;
  37
  38 #if 0
  39 #define DEBUGP printk
  40 #else
  41 #define DEBUGP(format, args...)
  42 #endif
  43
  44 static int icmpv6_pkt_to_tuple(const struct sk_buff *skb,
  45                                unsigned int dataoff,
  46                                struct nf_conntrack_tuple *tuple)
  47 {
  48         struct icmp6hdr _hdr, *hp;
  49
  50         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  51         if (hp == NULL)
  52                 return 0;
  53         tuple->dst.u.icmp.type = hp->icmp6_type;
  54         tuple->src.u.icmp.id = hp->icmp6_identifier;
  55         tuple->dst.u.icmp.code = hp->icmp6_code;
  56
  57         return 1;
  58 }
  59
  60 /* Add 1; spaces filled with 0. */
  61 static u_int8_t invmap[] = {
  62         [ICMPV6_ECHO_REQUEST - 128]     = ICMPV6_ECHO_REPLY + 1,
  63         [ICMPV6_ECHO_REPLY - 128]       = ICMPV6_ECHO_REQUEST + 1,
  64         [ICMPV6_NI_QUERY - 128]         = ICMPV6_NI_QUERY + 1,
  65         [ICMPV6_NI_REPLY - 128]         = ICMPV6_NI_REPLY +1
  66 };
  67
  68 static int icmpv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  69                                const struct nf_conntrack_tuple *orig)
  70 {
  71         int type = orig->dst.u.icmp.type - 128;
  72         if (type < 0 || type >= sizeof(invmap) || !invmap[type])
  73                 return 0;
  74
  75         tuple->src.u.icmp.id   = orig->src.u.icmp.id;
  76         tuple->dst.u.icmp.type = invmap[type] - 1;
  77         tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
  78         return 1;
  79 }
  80
  81 /* Print out the per-protocol part of the tuple. */
  82 static int icmpv6_print_tuple(struct seq_file *s,
  83                               const struct nf_conntrack_tuple *tuple)
  84 {
  85         return seq_printf(s, "type=%u code=%u id=%u ",
  86                           tuple->dst.u.icmp.type,
  87                           tuple->dst.u.icmp.code,
  88                           ntohs(tuple->src.u.icmp.id));
  89 }
  90
  91 /* Print out the private part of the conntrack. */
  92 static int icmpv6_print_conntrack(struct seq_file *s,
  93                                   const struct nf_conn *conntrack)
  94 {
  95         return 0;
  96 }
  97
  98 /* Returns verdict for packet, or -1 for invalid. */
  99 static int icmpv6_packet(struct nf_conn *ct,
 100                        const struct sk_buff *skb,
 101                        unsigned int dataoff,
 102                        enum ip_conntrack_info ctinfo,
 103                        int pf,
 104                        unsigned int hooknum)
 105 {
 106         /* Try to delete connection immediately after all replies:
 107            won't actually vanish as we still have skb, and del_timer
 108            means this will only run once even if count hits zero twice
 109            (theoretically possible with SMP) */
 110         if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
 111                 if (atomic_dec_and_test(&ct->proto.icmp.count)
 112                     && del_timer(&ct->timeout))
 113                         ct->timeout.function((unsigned long)ct);
 114         } else {
 115                 atomic_inc(&ct->proto.icmp.count);
 116                 nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);
 117                 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmpv6_timeout);
 118         }
 119
 120         return NF_ACCEPT;
 121 }
 122
 123 /* Called when a new connection for this protocol found. */
 124 static int icmpv6_new(struct nf_conn *conntrack,
 125                       const struct sk_buff *skb,
 126                       unsigned int dataoff)
 127 {
 128         static u_int8_t valid_new[] = {
 129                 [ICMPV6_ECHO_REQUEST - 128] = 1,
 130                 [ICMPV6_NI_QUERY - 128] = 1
 131         };
 132         int type = conntrack->tuplehash[0].tuple.dst.u.icmp.type - 128;
 133
 134         if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
 135                 /* Can't create a new ICMPv6 `conn' with this. */
 136                 DEBUGP("icmpv6: can't create new conn with type %u\n",
 137                        type + 128);
 138                 NF_CT_DUMP_TUPLE(&conntrack->tuplehash[0].tuple);
 139                 return 0;
 140         }
 141         atomic_set(&conntrack->proto.icmp.count, 0);
 142         return 1;
 143 }
 144
 145 extern int
 146 nf_ct_ipv6_skip_exthdr(struct sk_buff *skb, int start, u8 *nexthdrp, int len);
 147 extern struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv6;
 148 static int
 149 icmpv6_error_message(struct sk_buff *skb,
 150                      unsigned int icmp6off,
 151                      enum ip_conntrack_info *ctinfo,
 152                      unsigned int hooknum)
 153 {
 154         struct nf_conntrack_tuple intuple, origtuple;
 155         struct nf_conntrack_tuple_hash *h;
 156         struct icmp6hdr _hdr, *hp;
 157         unsigned int inip6off;
 158         struct nf_conntrack_protocol *inproto;
 159         u_int8_t inprotonum;
 160         unsigned int inprotoff;
 161
 162         NF_CT_ASSERT(skb->nfct == NULL);
 163
 164         hp = skb_header_pointer(skb, icmp6off, sizeof(_hdr), &_hdr);
 165         if (hp == NULL) {
 166                 DEBUGP("icmpv6_error: Can't get ICMPv6 hdr.\n");
 167                 return -NF_ACCEPT;
 168         }
 169
 170         inip6off = icmp6off + sizeof(_hdr);
 171         if (skb_copy_bits(skb, inip6off+offsetof(struct ipv6hdr, nexthdr),
 172                           &inprotonum, sizeof(inprotonum)) != 0) {
 173                 DEBUGP("icmpv6_error: Can't get nexthdr in inner IPv6 header.\n");
 174                 return -NF_ACCEPT;
 175         }
 176         inprotoff = nf_ct_ipv6_skip_exthdr(skb,
 177                                            inip6off + sizeof(struct ipv6hdr),
 178                                            &inprotonum,
 179                                            skb->len - inip6off
 180                                                     - sizeof(struct ipv6hdr));
 181
 182         if ((inprotoff < 0) || (inprotoff > skb->len) ||
 183             (inprotonum == NEXTHDR_FRAGMENT)) {
 184                 DEBUGP("icmpv6_error: Can't get protocol header in ICMPv6 payload.\n");
 185                 return -NF_ACCEPT;
 186         }
 187
 188         inproto = __nf_ct_proto_find(PF_INET6, inprotonum);
 189
 190         /* Are they talking about one of our connections? */
 191         if (!nf_ct_get_tuple(skb, inip6off, inprotoff, PF_INET6, inprotonum,
 192                              &origtuple, &nf_conntrack_l3proto_ipv6, inproto)) {
 193                 DEBUGP("icmpv6_error: Can't get tuple\n");
 194                 return -NF_ACCEPT;
 195         }
 196
 197         /* Ordinarily, we'd expect the inverted tupleproto, but it's
 198            been preserved inside the ICMP. */
 199         if (!nf_ct_invert_tuple(&intuple, &origtuple,
 200                                 &nf_conntrack_l3proto_ipv6, inproto)) {
 201                 DEBUGP("icmpv6_error: Can't invert tuple\n");
 202                 return -NF_ACCEPT;
 203         }
 204
 205         *ctinfo = IP_CT_RELATED;
 206
 207         h = nf_conntrack_find_get(&intuple, NULL);
 208         if (!h) {
 209                 DEBUGP("icmpv6_error: no match\n");
 210                 return -NF_ACCEPT;
 211         } else {
 212                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
 213                         *ctinfo += IP_CT_IS_REPLY;
 214         }
 215
 216         /* Update skb to refer to this connection */
 217         skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
 218         skb->nfctinfo = *ctinfo;
 219         return -NF_ACCEPT;
 220 }
 221
 222 static int
 223 icmpv6_error(struct sk_buff *skb, unsigned int dataoff,
 224              enum ip_conntrack_info *ctinfo, int pf, unsigned int hooknum)
 225 {
 226         struct icmp6hdr _ih, *icmp6h;
 227
 228         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 229         if (icmp6h == NULL) {
 230                 if (LOG_INVALID(IPPROTO_ICMPV6))
 231                 nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 232                               "nf_ct_icmpv6: short packet ");
 233                 return -NF_ACCEPT;
 234         }
 235
 236         if (nf_conntrack_checksum && hooknum == NF_IP6_PRE_ROUTING &&
 237             nf_ip6_checksum(skb, hooknum, dataoff, IPPROTO_ICMPV6)) {
 238                 nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 239                               "nf_ct_icmpv6: ICMPv6 checksum failed\n");
 240                 return -NF_ACCEPT;
 241         }
 242
 243         /* is not error message ? */
 244         if (icmp6h->icmp6_type >= 128)
 245                 return NF_ACCEPT;
 246
 247         return icmpv6_error_message(skb, dataoff, ctinfo, hooknum);
 248 }
 249
 250 #if defined(CONFIG_NF_CT_NETLINK) || \
 251     defined(CONFIG_NF_CT_NETLINK_MODULE)
 252
 253 #include <linux/netfilter/nfnetlink.h>
 254 #include <linux/netfilter/nfnetlink_conntrack.h>
 255 static int icmpv6_tuple_to_nfattr(struct sk_buff *skb,
 256                                   const struct nf_conntrack_tuple *t)
 257 {
 258         NFA_PUT(skb, CTA_PROTO_ICMPV6_ID, sizeof(u_int16_t),
 259                 &t->src.u.icmp.id);
 260         NFA_PUT(skb, CTA_PROTO_ICMPV6_TYPE, sizeof(u_int8_t),
 261                 &t->dst.u.icmp.type);
 262         NFA_PUT(skb, CTA_PROTO_ICMPV6_CODE, sizeof(u_int8_t),
 263                 &t->dst.u.icmp.code);
 264
 265         return 0;
 266
 267 nfattr_failure:
 268         return -1;
 269 }
 270
 271 static const size_t cta_min_proto[CTA_PROTO_MAX] = {
 272         [CTA_PROTO_ICMPV6_TYPE-1] = sizeof(u_int8_t),
 273         [CTA_PROTO_ICMPV6_CODE-1] = sizeof(u_int8_t),
 274         [CTA_PROTO_ICMPV6_ID-1]   = sizeof(u_int16_t)
 275 };
 276
 277 static int icmpv6_nfattr_to_tuple(struct nfattr *tb[],
 278                                 struct nf_conntrack_tuple *tuple)
 279 {
 280         if (!tb[CTA_PROTO_ICMPV6_TYPE-1]
 281             || !tb[CTA_PROTO_ICMPV6_CODE-1]
 282             || !tb[CTA_PROTO_ICMPV6_ID-1])
 283                 return -EINVAL;
 284
 285         if (nfattr_bad_size(tb, CTA_PROTO_MAX, cta_min_proto))
 286                 return -EINVAL;
 287
 288         tuple->dst.u.icmp.type =
 289                         *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMPV6_TYPE-1]);
 290         tuple->dst.u.icmp.code =
 291                         *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMPV6_CODE-1]);
 292         tuple->src.u.icmp.id =
 293                         *(u_int16_t *)NFA_DATA(tb[CTA_PROTO_ICMPV6_ID-1]);
 294
 295         if (tuple->dst.u.icmp.type < 128
 296             || tuple->dst.u.icmp.type - 128 >= sizeof(invmap)
 297             || !invmap[tuple->dst.u.icmp.type - 128])
 298                 return -EINVAL;
 299
 300         return 0;
 301 }
 302 #endif
 303
 304 struct nf_conntrack_protocol nf_conntrack_protocol_icmpv6 =
 305 {
 306         .l3proto                = PF_INET6,
 307         .proto                  = IPPROTO_ICMPV6,
 308         .name                   = "icmpv6",
 309         .pkt_to_tuple           = icmpv6_pkt_to_tuple,
 310         .invert_tuple           = icmpv6_invert_tuple,
 311         .print_tuple            = icmpv6_print_tuple,
 312         .print_conntrack        = icmpv6_print_conntrack,
 313         .packet                 = icmpv6_packet,
 314         .new                    = icmpv6_new,
 315         .error                  = icmpv6_error,
 316 #if defined(CONFIG_NF_CT_NETLINK) || \
 317     defined(CONFIG_NF_CT_NETLINK_MODULE)
 318         .tuple_to_nfattr        = icmpv6_tuple_to_nfattr,
 319         .nfattr_to_tuple        = icmpv6_nfattr_to_tuple,
 320 #endif
 321 };
 322
 323 EXPORT_SYMBOL(nf_conntrack_protocol_icmpv6);