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