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 icmp6hdr _hdr, *hp;
 140         unsigned int inip6off;
 141         struct nf_conntrack_l4proto *inproto;
 142         u_int8_t inprotonum;
 143         unsigned int inprotoff;
 144
 145         NF_CT_ASSERT(skb->nfct == NULL);
 146
 147         hp = skb_header_pointer(skb, icmp6off, sizeof(_hdr), &_hdr);
 148         if (hp == NULL) {
 149                 pr_debug("icmpv6_error: Can't get ICMPv6 hdr.\n");
 150                 return -NF_ACCEPT;
 151         }
 152
 153         inip6off = icmp6off + sizeof(_hdr);
 154         if (skb_copy_bits(skb, inip6off+offsetof(struct ipv6hdr, nexthdr),
 155                           &inprotonum, sizeof(inprotonum)) != 0) {
 156                 pr_debug("icmpv6_error: Can't get nexthdr in inner IPv6 "
 157                          "header.\n");
 158                 return -NF_ACCEPT;
 159         }
 160         inprotoff = nf_ct_ipv6_skip_exthdr(skb,
 161                                            inip6off + sizeof(struct ipv6hdr),
 162                                            &inprotonum,
 163                                            skb->len - inip6off
 164                                                     - sizeof(struct ipv6hdr));
 165
 166         if ((inprotoff > skb->len) || (inprotonum == NEXTHDR_FRAGMENT)) {
 167                 pr_debug("icmpv6_error: Can't get protocol header in ICMPv6 "
 168                          "payload.\n");
 169                 return -NF_ACCEPT;
 170         }
 171
 172         /* rcu_read_lock()ed by nf_hook_slow */
 173         inproto = __nf_ct_l4proto_find(PF_INET6, inprotonum);
 174
 175         /* Are they talking about one of our connections? */
 176         if (!nf_ct_get_tuple(skb, inip6off, inprotoff, PF_INET6, inprotonum,
 177                              &origtuple, &nf_conntrack_l3proto_ipv6, inproto)) {
 178                 pr_debug("icmpv6_error: Can't get tuple\n");
 179                 return -NF_ACCEPT;
 180         }
 181
 182         /* Ordinarily, we'd expect the inverted tupleproto, but it's
 183            been preserved inside the ICMP. */
 184         if (!nf_ct_invert_tuple(&intuple, &origtuple,
 185                                 &nf_conntrack_l3proto_ipv6, inproto)) {
 186                 pr_debug("icmpv6_error: Can't invert tuple\n");
 187                 return -NF_ACCEPT;
 188         }
 189
 190         *ctinfo = IP_CT_RELATED;
 191
 192         h = nf_conntrack_find_get(&intuple);
 193         if (!h) {
 194                 pr_debug("icmpv6_error: no match\n");
 195                 return -NF_ACCEPT;
 196         } else {
 197                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
 198                         *ctinfo += IP_CT_IS_REPLY;
 199         }
 200
 201         /* Update skb to refer to this connection */
 202         skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
 203         skb->nfctinfo = *ctinfo;
 204         return -NF_ACCEPT;
 205 }
 206
 207 static int
 208 icmpv6_error(struct sk_buff *skb, unsigned int dataoff,
 209              enum ip_conntrack_info *ctinfo, int pf, unsigned int hooknum)
 210 {
 211         struct icmp6hdr _ih, *icmp6h;
 212
 213         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 214         if (icmp6h == NULL) {
 215                 if (LOG_INVALID(IPPROTO_ICMPV6))
 216                 nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 217                               "nf_ct_icmpv6: short packet ");
 218                 return -NF_ACCEPT;
 219         }
 220
 221         if (nf_conntrack_checksum && hooknum == NF_IP6_PRE_ROUTING &&
 222             nf_ip6_checksum(skb, hooknum, dataoff, IPPROTO_ICMPV6)) {
 223                 nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 224                               "nf_ct_icmpv6: ICMPv6 checksum failed\n");
 225                 return -NF_ACCEPT;
 226         }
 227
 228         /* is not error message ? */
 229         if (icmp6h->icmp6_type >= 128)
 230                 return NF_ACCEPT;
 231
 232         return icmpv6_error_message(skb, dataoff, ctinfo, hooknum);
 233 }
 234
 235 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 236
 237 #include <linux/netfilter/nfnetlink.h>
 238 #include <linux/netfilter/nfnetlink_conntrack.h>
 239 static int icmpv6_tuple_to_nfattr(struct sk_buff *skb,
 240                                   const struct nf_conntrack_tuple *t)
 241 {
 242         NFA_PUT(skb, CTA_PROTO_ICMPV6_ID, sizeof(u_int16_t),
 243                 &t->src.u.icmp.id);
 244         NFA_PUT(skb, CTA_PROTO_ICMPV6_TYPE, sizeof(u_int8_t),
 245                 &t->dst.u.icmp.type);
 246         NFA_PUT(skb, CTA_PROTO_ICMPV6_CODE, sizeof(u_int8_t),
 247                 &t->dst.u.icmp.code);
 248
 249         return 0;
 250
 251 nfattr_failure:
 252         return -1;
 253 }
 254
 255 static const size_t cta_min_proto[CTA_PROTO_MAX] = {
 256         [CTA_PROTO_ICMPV6_TYPE-1] = sizeof(u_int8_t),
 257         [CTA_PROTO_ICMPV6_CODE-1] = sizeof(u_int8_t),
 258         [CTA_PROTO_ICMPV6_ID-1]   = sizeof(u_int16_t)
 259 };
 260
 261 static int icmpv6_nfattr_to_tuple(struct nfattr *tb[],
 262                                 struct nf_conntrack_tuple *tuple)
 263 {
 264         if (!tb[CTA_PROTO_ICMPV6_TYPE-1]
 265             || !tb[CTA_PROTO_ICMPV6_CODE-1]
 266             || !tb[CTA_PROTO_ICMPV6_ID-1])
 267                 return -EINVAL;
 268
 269         if (nfattr_bad_size(tb, CTA_PROTO_MAX, cta_min_proto))
 270                 return -EINVAL;
 271
 272         tuple->dst.u.icmp.type =
 273                         *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMPV6_TYPE-1]);
 274         tuple->dst.u.icmp.code =
 275                         *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMPV6_CODE-1]);
 276         tuple->src.u.icmp.id =
 277                         *(__be16 *)NFA_DATA(tb[CTA_PROTO_ICMPV6_ID-1]);
 278
 279         if (tuple->dst.u.icmp.type < 128
 280             || tuple->dst.u.icmp.type - 128 >= sizeof(invmap)
 281             || !invmap[tuple->dst.u.icmp.type - 128])
 282                 return -EINVAL;
 283
 284         return 0;
 285 }
 286 #endif
 287
 288 #ifdef CONFIG_SYSCTL
 289 static struct ctl_table_header *icmpv6_sysctl_header;
 290 static struct ctl_table icmpv6_sysctl_table[] = {
 291         {
 292                 .ctl_name       = NET_NF_CONNTRACK_ICMPV6_TIMEOUT,
 293                 .procname       = "nf_conntrack_icmpv6_timeout",
 294                 .data           = &nf_ct_icmpv6_timeout,
 295                 .maxlen         = sizeof(unsigned int),
 296                 .mode           = 0644,
 297                 .proc_handler   = &proc_dointvec_jiffies,
 298         },
 299         {
 300                 .ctl_name       = 0
 301         }
 302 };
 303 #endif /* CONFIG_SYSCTL */
 304
 305 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 =
 306 {
 307         .l3proto                = PF_INET6,
 308         .l4proto                = IPPROTO_ICMPV6,
 309         .name                   = "icmpv6",
 310         .pkt_to_tuple           = icmpv6_pkt_to_tuple,
 311         .invert_tuple           = icmpv6_invert_tuple,
 312         .print_tuple            = icmpv6_print_tuple,
 313         .print_conntrack        = icmpv6_print_conntrack,
 314         .packet                 = icmpv6_packet,
 315         .new                    = icmpv6_new,
 316         .error                  = icmpv6_error,
 317 #if defined(CONFIG_NF_CT_NETLINK) || 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 #ifdef CONFIG_SYSCTL
 322         .ctl_table_header       = &icmpv6_sysctl_header,
 323         .ctl_table              = icmpv6_sysctl_table,
 324 #endif
 325 };
 326
 327 EXPORT_SYMBOL(nf_conntrack_l4proto_icmpv6);