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/nf_conntrack_zones.h>
  27 #include <net/netfilter/ipv6/nf_conntrack_icmpv6.h>
  28 #include <net/netfilter/nf_log.h>
  29
  30 static unsigned int nf_ct_icmpv6_timeout __read_mostly = 30*HZ;
  31
  32 static bool icmpv6_pkt_to_tuple(const struct sk_buff *skb,
  33                                 unsigned int dataoff,
  34                                 struct nf_conntrack_tuple *tuple)
  35 {
  36         const struct icmp6hdr *hp;
  37         struct icmp6hdr _hdr;
  38
  39         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  40         if (hp == NULL)
  41                 return false;
  42         tuple->dst.u.icmp.type = hp->icmp6_type;
  43         tuple->src.u.icmp.id = hp->icmp6_identifier;
  44         tuple->dst.u.icmp.code = hp->icmp6_code;
  45
  46         return true;
  47 }
  48
  49 /* Add 1; spaces filled with 0. */
  50 static const u_int8_t invmap[] = {
  51         [ICMPV6_ECHO_REQUEST - 128]     = ICMPV6_ECHO_REPLY + 1,
  52         [ICMPV6_ECHO_REPLY - 128]       = ICMPV6_ECHO_REQUEST + 1,
  53         [ICMPV6_NI_QUERY - 128]         = ICMPV6_NI_REPLY + 1,
  54         [ICMPV6_NI_REPLY - 128]         = ICMPV6_NI_QUERY +1
  55 };
  56
  57 static const u_int8_t noct_valid_new[] = {
  58         [ICMPV6_MGM_QUERY - 130] = 1,
  59         [ICMPV6_MGM_REPORT -130] = 1,
  60         [ICMPV6_MGM_REDUCTION - 130] = 1,
  61         [NDISC_ROUTER_SOLICITATION - 130] = 1,
  62         [NDISC_ROUTER_ADVERTISEMENT - 130] = 1,
  63         [NDISC_NEIGHBOUR_SOLICITATION - 130] = 1,
  64         [NDISC_NEIGHBOUR_ADVERTISEMENT - 130] = 1,
  65         [ICMPV6_MLD2_REPORT - 130] = 1
  66 };
  67
  68 static bool 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 false;
  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 true;
  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 /* Returns verdict for packet, or -1 for invalid. */
  92 static int icmpv6_packet(struct nf_conn *ct,
  93                        const struct sk_buff *skb,
  94                        unsigned int dataoff,
  95                        enum ip_conntrack_info ctinfo,
  96                        u_int8_t pf,
  97                        unsigned int hooknum)
  98 {
  99         /* Do not immediately delete the connection after the first
 100            successful reply to avoid excessive conntrackd traffic
 101            and also to handle correctly ICMP echo reply duplicates. */
 102         nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmpv6_timeout);
 103
 104         return NF_ACCEPT;
 105 }
 106
 107 /* Called when a new connection for this protocol found. */
 108 static bool icmpv6_new(struct nf_conn *ct, const struct sk_buff *skb,
 109                        unsigned int dataoff)
 110 {
 111         static const u_int8_t valid_new[] = {
 112                 [ICMPV6_ECHO_REQUEST - 128] = 1,
 113                 [ICMPV6_NI_QUERY - 128] = 1
 114         };
 115         int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;
 116
 117         if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
 118                 /* Can't create a new ICMPv6 `conn' with this. */
 119                 pr_debug("icmpv6: can't create new conn with type %u\n",
 120                          type + 128);
 121                 nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
 122                 if (LOG_INVALID(nf_ct_net(ct), IPPROTO_ICMPV6))
 123                         nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 124                                       "nf_ct_icmpv6: invalid new with type %d ",
 125                                       type + 128);
 126                 return false;
 127         }
 128         return true;
 129 }
 130
 131 static int
 132 icmpv6_error_message(struct net *net, struct nf_conn *tmpl,
 133                      struct sk_buff *skb,
 134                      unsigned int icmp6off,
 135                      enum ip_conntrack_info *ctinfo,
 136                      unsigned int hooknum)
 137 {
 138         struct nf_conntrack_tuple intuple, origtuple;
 139         const struct nf_conntrack_tuple_hash *h;
 140         const struct nf_conntrack_l4proto *inproto;
 141         u16 zone = tmpl ? nf_ct_zone(tmpl) : NF_CT_DEFAULT_ZONE;
 142
 143         NF_CT_ASSERT(skb->nfct == NULL);
 144
 145         /* Are they talking about one of our connections? */
 146         if (!nf_ct_get_tuplepr(skb,
 147                                skb_network_offset(skb)
 148                                 + sizeof(struct ipv6hdr)
 149                                 + sizeof(struct icmp6hdr),
 150                                PF_INET6, &origtuple)) {
 151                 pr_debug("icmpv6_error: Can't get tuple\n");
 152                 return -NF_ACCEPT;
 153         }
 154
 155         /* rcu_read_lock()ed by nf_hook_slow */
 156         inproto = __nf_ct_l4proto_find(PF_INET6, origtuple.dst.protonum);
 157
 158         /* Ordinarily, we'd expect the inverted tupleproto, but it's
 159            been preserved inside the ICMP. */
 160         if (!nf_ct_invert_tuple(&intuple, &origtuple,
 161                                 &nf_conntrack_l3proto_ipv6, inproto)) {
 162                 pr_debug("icmpv6_error: Can't invert tuple\n");
 163                 return -NF_ACCEPT;
 164         }
 165
 166         *ctinfo = IP_CT_RELATED;
 167
 168         h = nf_conntrack_find_get(net, zone, &intuple);
 169         if (!h) {
 170                 pr_debug("icmpv6_error: no match\n");
 171                 return -NF_ACCEPT;
 172         } else {
 173                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
 174                         *ctinfo += IP_CT_IS_REPLY;
 175         }
 176
 177         /* Update skb to refer to this connection */
 178         skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
 179         skb->nfctinfo = *ctinfo;
 180         return -NF_ACCEPT;
 181 }
 182
 183 static int
 184 icmpv6_error(struct net *net, struct nf_conn *tmpl,
 185              struct sk_buff *skb, unsigned int dataoff,
 186              enum ip_conntrack_info *ctinfo, u_int8_t pf, unsigned int hooknum)
 187 {
 188         const struct icmp6hdr *icmp6h;
 189         struct icmp6hdr _ih;
 190         int type;
 191
 192         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 193         if (icmp6h == NULL) {
 194                 if (LOG_INVALID(net, IPPROTO_ICMPV6))
 195                 nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 196                               "nf_ct_icmpv6: short packet ");
 197                 return -NF_ACCEPT;
 198         }
 199
 200         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 201             nf_ip6_checksum(skb, hooknum, dataoff, IPPROTO_ICMPV6)) {
 202                 if (LOG_INVALID(net, IPPROTO_ICMPV6))
 203                         nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 204                                       "nf_ct_icmpv6: ICMPv6 checksum failed ");
 205                 return -NF_ACCEPT;
 206         }
 207
 208         type = icmp6h->icmp6_type - 130;
 209         if (type >= 0 && type < sizeof(noct_valid_new) &&
 210             noct_valid_new[type]) {
 211                 skb->nfct = &nf_ct_untracked_get()->ct_general;
 212                 skb->nfctinfo = IP_CT_NEW;
 213                 nf_conntrack_get(skb->nfct);
 214                 return NF_ACCEPT;
 215         }
 216
 217         /* is not error message ? */
 218         if (icmp6h->icmp6_type >= 128)
 219                 return NF_ACCEPT;
 220
 221         return icmpv6_error_message(net, tmpl, skb, dataoff, ctinfo, hooknum);
 222 }
 223
 224 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 225
 226 #include <linux/netfilter/nfnetlink.h>
 227 #include <linux/netfilter/nfnetlink_conntrack.h>
 228 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
 229                                   const struct nf_conntrack_tuple *t)
 230 {
 231         NLA_PUT_BE16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id);
 232         NLA_PUT_U8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type);
 233         NLA_PUT_U8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code);
 234
 235         return 0;
 236
 237 nla_put_failure:
 238         return -1;
 239 }
 240
 241 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
 242         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
 243         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
 244         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
 245 };
 246
 247 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
 248                                 struct nf_conntrack_tuple *tuple)
 249 {
 250         if (!tb[CTA_PROTO_ICMPV6_TYPE] ||
 251             !tb[CTA_PROTO_ICMPV6_CODE] ||
 252             !tb[CTA_PROTO_ICMPV6_ID])
 253                 return -EINVAL;
 254
 255         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
 256         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
 257         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
 258
 259         if (tuple->dst.u.icmp.type < 128 ||
 260             tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
 261             !invmap[tuple->dst.u.icmp.type - 128])
 262                 return -EINVAL;
 263
 264         return 0;
 265 }
 266
 267 static int icmpv6_nlattr_tuple_size(void)
 268 {
 269         return nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
 270 }
 271 #endif
 272
 273 #ifdef CONFIG_SYSCTL
 274 static struct ctl_table_header *icmpv6_sysctl_header;
 275 static struct ctl_table icmpv6_sysctl_table[] = {
 276         {
 277                 .procname       = "nf_conntrack_icmpv6_timeout",
 278                 .data           = &nf_ct_icmpv6_timeout,
 279                 .maxlen         = sizeof(unsigned int),
 280                 .mode           = 0644,
 281                 .proc_handler   = proc_dointvec_jiffies,
 282         },
 283         { }
 284 };
 285 #endif /* CONFIG_SYSCTL */
 286
 287 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 __read_mostly =
 288 {
 289         .l3proto                = PF_INET6,
 290         .l4proto                = IPPROTO_ICMPV6,
 291         .name                   = "icmpv6",
 292         .pkt_to_tuple           = icmpv6_pkt_to_tuple,
 293         .invert_tuple           = icmpv6_invert_tuple,
 294         .print_tuple            = icmpv6_print_tuple,
 295         .packet                 = icmpv6_packet,
 296         .new                    = icmpv6_new,
 297         .error                  = icmpv6_error,
 298 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 299         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
 300         .nlattr_tuple_size      = icmpv6_nlattr_tuple_size,
 301         .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
 302         .nla_policy             = icmpv6_nla_policy,
 303 #endif
 304 #ifdef CONFIG_SYSCTL
 305         .ctl_table_header       = &icmpv6_sysctl_header,
 306         .ctl_table              = icmpv6_sysctl_table,
 307 #endif
 308 };