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/timer.h>
  21 #include <linux/module.h>
  22 #include <linux/netfilter.h>
  23 #include <linux/in6.h>
  24 #include <linux/icmpv6.h>
  25 #include <linux/ipv6.h>
  26 #include <net/ipv6.h>
  27 #include <net/ip6_checksum.h>
  28 #include <linux/seq_file.h>
  29 #include <linux/netfilter_ipv6.h>
  30 #include <net/netfilter/nf_conntrack_tuple.h>
  31 #include <net/netfilter/nf_conntrack_l4proto.h>
  32 #include <net/netfilter/nf_conntrack_core.h>
  33 #include <net/netfilter/ipv6/nf_conntrack_icmpv6.h>
  34
  35 static unsigned long nf_ct_icmpv6_timeout __read_mostly = 30*HZ;
  36
  37 #if 0
  38 #define DEBUGP printk
  39 #else
  40 #define DEBUGP(format, args...)
  41 #endif
  42
  43 static int icmpv6_pkt_to_tuple(const struct sk_buff *skb,
  44                                unsigned int dataoff,
  45                                struct nf_conntrack_tuple *tuple)
  46 {
  47         struct icmp6hdr _hdr, *hp;
  48
  49         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  50         if (hp == NULL)
  51                 return 0;
  52         tuple->dst.u.icmp.type = hp->icmp6_type;
  53         tuple->src.u.icmp.id = hp->icmp6_identifier;
  54         tuple->dst.u.icmp.code = hp->icmp6_code;
  55
  56         return 1;
  57 }
  58
  59 /* Add 1; spaces filled with 0. */
  60 static u_int8_t invmap[] = {
  61         [ICMPV6_ECHO_REQUEST - 128]     = ICMPV6_ECHO_REPLY + 1,
  62         [ICMPV6_ECHO_REPLY - 128]       = ICMPV6_ECHO_REQUEST + 1,
  63         [ICMPV6_NI_QUERY - 128]         = ICMPV6_NI_QUERY + 1,
  64         [ICMPV6_NI_REPLY - 128]         = ICMPV6_NI_REPLY +1
  65 };
  66
  67 static int icmpv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  68                                const struct nf_conntrack_tuple *orig)
  69 {
  70         int type = orig->dst.u.icmp.type - 128;
  71         if (type < 0 || type >= sizeof(invmap) || !invmap[type])
  72                 return 0;
  73
  74         tuple->src.u.icmp.id   = orig->src.u.icmp.id;
  75         tuple->dst.u.icmp.type = invmap[type] - 1;
  76         tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
  77         return 1;
  78 }
  79
  80 /* Print out the per-protocol part of the tuple. */
  81 static int icmpv6_print_tuple(struct seq_file *s,
  82                               const struct nf_conntrack_tuple *tuple)
  83 {
  84         return seq_printf(s, "type=%u code=%u id=%u ",
  85                           tuple->dst.u.icmp.type,
  86                           tuple->dst.u.icmp.code,
  87                           ntohs(tuple->src.u.icmp.id));
  88 }
  89
  90 /* Print out the private part of the conntrack. */
  91 static int icmpv6_print_conntrack(struct seq_file *s,
  92                                   const struct nf_conn *conntrack)
  93 {
  94         return 0;
  95 }
  96
  97 /* Returns verdict for packet, or -1 for invalid. */
  98 static int icmpv6_packet(struct nf_conn *ct,
  99                        const struct sk_buff *skb,
 100                        unsigned int dataoff,
 101                        enum ip_conntrack_info ctinfo,
 102                        int pf,
 103                        unsigned int hooknum)
 104 {
 105         /* Try to delete connection immediately after all replies:
 106            won't actually vanish as we still have skb, and del_timer
 107            means this will only run once even if count hits zero twice
 108            (theoretically possible with SMP) */
 109         if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
 110                 if (atomic_dec_and_test(&ct->proto.icmp.count)
 111                     && del_timer(&ct->timeout))
 112                         ct->timeout.function((unsigned long)ct);
 113         } else {
 114                 atomic_inc(&ct->proto.icmp.count);
 115                 nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);
 116                 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmpv6_timeout);
 117         }
 118
 119         return NF_ACCEPT;
 120 }
 121
 122 /* Called when a new connection for this protocol found. */
 123 static int icmpv6_new(struct nf_conn *conntrack,
 124                       const struct sk_buff *skb,
 125                       unsigned int dataoff)
 126 {
 127         static u_int8_t valid_new[] = {
 128                 [ICMPV6_ECHO_REQUEST - 128] = 1,
 129                 [ICMPV6_NI_QUERY - 128] = 1
 130         };
 131         int type = conntrack->tuplehash[0].tuple.dst.u.icmp.type - 128;
 132
 133         if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
 134                 /* Can't create a new ICMPv6 `conn' with this. */
 135                 DEBUGP("icmpv6: can't create new conn with type %u\n",
 136                        type + 128);
 137                 NF_CT_DUMP_TUPLE(&conntrack->tuplehash[0].tuple);
 138                 return 0;
 139         }
 140         atomic_set(&conntrack->proto.icmp.count, 0);
 141         return 1;
 142 }
 143
 144 static int
 145 icmpv6_error_message(struct sk_buff *skb,
 146                      unsigned int icmp6off,
 147                      enum ip_conntrack_info *ctinfo,
 148                      unsigned int hooknum)
 149 {
 150         struct nf_conntrack_tuple intuple, origtuple;
 151         struct nf_conntrack_tuple_hash *h;
 152         struct icmp6hdr _hdr, *hp;
 153         unsigned int inip6off;
 154         struct nf_conntrack_l4proto *inproto;
 155         u_int8_t inprotonum;
 156         unsigned int inprotoff;
 157
 158         NF_CT_ASSERT(skb->nfct == NULL);
 159
 160         hp = skb_header_pointer(skb, icmp6off, sizeof(_hdr), &_hdr);
 161         if (hp == NULL) {
 162                 DEBUGP("icmpv6_error: Can't get ICMPv6 hdr.\n");
 163                 return -NF_ACCEPT;
 164         }
 165
 166         inip6off = icmp6off + sizeof(_hdr);
 167         if (skb_copy_bits(skb, inip6off+offsetof(struct ipv6hdr, nexthdr),
 168                           &inprotonum, sizeof(inprotonum)) != 0) {
 169                 DEBUGP("icmpv6_error: Can't get nexthdr in inner IPv6 header.\n");
 170                 return -NF_ACCEPT;
 171         }
 172         inprotoff = nf_ct_ipv6_skip_exthdr(skb,
 173                                            inip6off + sizeof(struct ipv6hdr),
 174                                            &inprotonum,
 175                                            skb->len - inip6off
 176                                                     - sizeof(struct ipv6hdr));
 177
 178         if ((inprotoff < 0) || (inprotoff > skb->len) ||
 179             (inprotonum == NEXTHDR_FRAGMENT)) {
 180                 DEBUGP("icmpv6_error: Can't get protocol header in ICMPv6 payload.\n");
 181                 return -NF_ACCEPT;
 182         }
 183
 184         /* rcu_read_lock()ed by nf_hook_slow */
 185         inproto = __nf_ct_l4proto_find(PF_INET6, inprotonum);
 186
 187         /* Are they talking about one of our connections? */
 188         if (!nf_ct_get_tuple(skb, inip6off, inprotoff, PF_INET6, inprotonum,
 189                              &origtuple, &nf_conntrack_l3proto_ipv6, inproto)) {
 190                 DEBUGP("icmpv6_error: Can't get tuple\n");
 191                 return -NF_ACCEPT;
 192         }
 193
 194         /* Ordinarily, we'd expect the inverted tupleproto, but it's
 195            been preserved inside the ICMP. */
 196         if (!nf_ct_invert_tuple(&intuple, &origtuple,
 197                                 &nf_conntrack_l3proto_ipv6, inproto)) {
 198                 DEBUGP("icmpv6_error: Can't invert tuple\n");
 199                 return -NF_ACCEPT;
 200         }
 201
 202         *ctinfo = IP_CT_RELATED;
 203
 204         h = nf_conntrack_find_get(&intuple, NULL);
 205         if (!h) {
 206                 DEBUGP("icmpv6_error: no match\n");
 207                 return -NF_ACCEPT;
 208         } else {
 209                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
 210                         *ctinfo += IP_CT_IS_REPLY;
 211         }
 212
 213         /* Update skb to refer to this connection */
 214         skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
 215         skb->nfctinfo = *ctinfo;
 216         return -NF_ACCEPT;
 217 }
 218
 219 static int
 220 icmpv6_error(struct sk_buff *skb, unsigned int dataoff,
 221              enum ip_conntrack_info *ctinfo, int pf, unsigned int hooknum)
 222 {
 223         struct icmp6hdr _ih, *icmp6h;
 224
 225         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 226         if (icmp6h == NULL) {
 227                 if (LOG_INVALID(IPPROTO_ICMPV6))
 228                 nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 229                               "nf_ct_icmpv6: short packet ");
 230                 return -NF_ACCEPT;
 231         }
 232
 233         if (nf_conntrack_checksum && hooknum == NF_IP6_PRE_ROUTING &&
 234             nf_ip6_checksum(skb, hooknum, dataoff, IPPROTO_ICMPV6)) {
 235                 nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 236                               "nf_ct_icmpv6: ICMPv6 checksum failed\n");
 237                 return -NF_ACCEPT;
 238         }
 239
 240         /* is not error message ? */
 241         if (icmp6h->icmp6_type >= 128)
 242                 return NF_ACCEPT;
 243
 244         return icmpv6_error_message(skb, dataoff, ctinfo, hooknum);
 245 }
 246
 247 #if defined(CONFIG_NF_CT_NETLINK) || \
 248     defined(CONFIG_NF_CT_NETLINK_MODULE)
 249
 250 #include <linux/netfilter/nfnetlink.h>
 251 #include <linux/netfilter/nfnetlink_conntrack.h>
 252 static int icmpv6_tuple_to_nfattr(struct sk_buff *skb,
 253                                   const struct nf_conntrack_tuple *t)
 254 {
 255         NFA_PUT(skb, CTA_PROTO_ICMPV6_ID, sizeof(u_int16_t),
 256                 &t->src.u.icmp.id);
 257         NFA_PUT(skb, CTA_PROTO_ICMPV6_TYPE, sizeof(u_int8_t),
 258                 &t->dst.u.icmp.type);
 259         NFA_PUT(skb, CTA_PROTO_ICMPV6_CODE, sizeof(u_int8_t),
 260                 &t->dst.u.icmp.code);
 261
 262         return 0;
 263
 264 nfattr_failure:
 265         return -1;
 266 }
 267
 268 static const size_t cta_min_proto[CTA_PROTO_MAX] = {
 269         [CTA_PROTO_ICMPV6_TYPE-1] = sizeof(u_int8_t),
 270         [CTA_PROTO_ICMPV6_CODE-1] = sizeof(u_int8_t),
 271         [CTA_PROTO_ICMPV6_ID-1]   = sizeof(u_int16_t)
 272 };
 273
 274 static int icmpv6_nfattr_to_tuple(struct nfattr *tb[],
 275                                 struct nf_conntrack_tuple *tuple)
 276 {
 277         if (!tb[CTA_PROTO_ICMPV6_TYPE-1]
 278             || !tb[CTA_PROTO_ICMPV6_CODE-1]
 279             || !tb[CTA_PROTO_ICMPV6_ID-1])
 280                 return -EINVAL;
 281
 282         if (nfattr_bad_size(tb, CTA_PROTO_MAX, cta_min_proto))
 283                 return -EINVAL;
 284
 285         tuple->dst.u.icmp.type =
 286                         *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMPV6_TYPE-1]);
 287         tuple->dst.u.icmp.code =
 288                         *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMPV6_CODE-1]);
 289         tuple->src.u.icmp.id =
 290                         *(__be16 *)NFA_DATA(tb[CTA_PROTO_ICMPV6_ID-1]);
 291
 292         if (tuple->dst.u.icmp.type < 128
 293             || tuple->dst.u.icmp.type - 128 >= sizeof(invmap)
 294             || !invmap[tuple->dst.u.icmp.type - 128])
 295                 return -EINVAL;
 296
 297         return 0;
 298 }
 299 #endif
 300
 301 #ifdef CONFIG_SYSCTL
 302 static struct ctl_table_header *icmpv6_sysctl_header;
 303 static struct ctl_table icmpv6_sysctl_table[] = {
 304         {
 305                 .ctl_name       = NET_NF_CONNTRACK_ICMPV6_TIMEOUT,
 306                 .procname       = "nf_conntrack_icmpv6_timeout",
 307                 .data           = &nf_ct_icmpv6_timeout,
 308                 .maxlen         = sizeof(unsigned int),
 309                 .mode           = 0644,
 310                 .proc_handler   = &proc_dointvec_jiffies,
 311         },
 312         {
 313                 .ctl_name       = 0
 314         }
 315 };
 316 #endif /* CONFIG_SYSCTL */
 317
 318 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 =
 319 {
 320         .l3proto                = PF_INET6,
 321         .l4proto                = IPPROTO_ICMPV6,
 322         .name                   = "icmpv6",
 323         .pkt_to_tuple           = icmpv6_pkt_to_tuple,
 324         .invert_tuple           = icmpv6_invert_tuple,
 325         .print_tuple            = icmpv6_print_tuple,
 326         .print_conntrack        = icmpv6_print_conntrack,
 327         .packet                 = icmpv6_packet,
 328         .new                    = icmpv6_new,
 329         .error                  = icmpv6_error,
 330 #if defined(CONFIG_NF_CT_NETLINK) || \
 331     defined(CONFIG_NF_CT_NETLINK_MODULE)
 332         .tuple_to_nfattr        = icmpv6_tuple_to_nfattr,
 333         .nfattr_to_tuple        = icmpv6_nfattr_to_tuple,
 334 #endif
 335 #ifdef CONFIG_SYSCTL
 336         .ctl_table_header       = &icmpv6_sysctl_header,
 337         .ctl_table              = icmpv6_sysctl_table,
 338 #endif
 339 };
 340
 341 EXPORT_SYMBOL(nf_conntrack_l4proto_icmpv6);