net/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_timeout.h>
  27 #include <net/netfilter/nf_conntrack_zones.h>
  28 #include <net/netfilter/ipv6/nf_conntrack_icmpv6.h>
  29 #include <net/netfilter/nf_log.h>
  30
  31 static const unsigned int nf_ct_icmpv6_timeout = 30*HZ;
  32
  33 bool icmpv6_pkt_to_tuple(const struct sk_buff *skb,
  34                          unsigned int dataoff,
  35                          struct net *net,
  36                          struct nf_conntrack_tuple *tuple)
  37 {
  38         const struct icmp6hdr *hp;
  39         struct icmp6hdr _hdr;
  40
  41         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  42         if (hp == NULL)
  43                 return false;
  44         tuple->dst.u.icmp.type = hp->icmp6_type;
  45         tuple->src.u.icmp.id = hp->icmp6_identifier;
  46         tuple->dst.u.icmp.code = hp->icmp6_code;
  47
  48         return true;
  49 }
  50
  51 /* Add 1; spaces filled with 0. */
  52 static const u_int8_t invmap[] = {
  53         [ICMPV6_ECHO_REQUEST - 128]     = ICMPV6_ECHO_REPLY + 1,
  54         [ICMPV6_ECHO_REPLY - 128]       = ICMPV6_ECHO_REQUEST + 1,
  55         [ICMPV6_NI_QUERY - 128]         = ICMPV6_NI_REPLY + 1,
  56         [ICMPV6_NI_REPLY - 128]         = ICMPV6_NI_QUERY + 1
  57 };
  58
  59 static const u_int8_t noct_valid_new[] = {
  60         [ICMPV6_MGM_QUERY - 130] = 1,
  61         [ICMPV6_MGM_REPORT - 130] = 1,
  62         [ICMPV6_MGM_REDUCTION - 130] = 1,
  63         [NDISC_ROUTER_SOLICITATION - 130] = 1,
  64         [NDISC_ROUTER_ADVERTISEMENT - 130] = 1,
  65         [NDISC_NEIGHBOUR_SOLICITATION - 130] = 1,
  66         [NDISC_NEIGHBOUR_ADVERTISEMENT - 130] = 1,
  67         [ICMPV6_MLD2_REPORT - 130] = 1
  68 };
  69
  70 bool nf_conntrack_invert_icmpv6_tuple(struct nf_conntrack_tuple *tuple,
  71                                       const struct nf_conntrack_tuple *orig)
  72 {
  73         int type = orig->dst.u.icmp.type - 128;
  74         if (type < 0 || type >= sizeof(invmap) || !invmap[type])
  75                 return false;
  76
  77         tuple->src.u.icmp.id   = orig->src.u.icmp.id;
  78         tuple->dst.u.icmp.type = invmap[type] - 1;
  79         tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
  80         return true;
  81 }
  82
  83 static unsigned int *icmpv6_get_timeouts(struct net *net)
  84 {
  85         return &nf_icmpv6_pernet(net)->timeout;
  86 }
  87
  88 /* Returns verdict for packet, or -1 for invalid. */
  89 int nf_conntrack_icmpv6_packet(struct nf_conn *ct,
  90                                struct sk_buff *skb,
  91                                enum ip_conntrack_info ctinfo,
  92                                const struct nf_hook_state *state)
  93 {
  94         unsigned int *timeout = nf_ct_timeout_lookup(ct);
  95         static const u8 valid_new[] = {
  96                 [ICMPV6_ECHO_REQUEST - 128] = 1,
  97                 [ICMPV6_NI_QUERY - 128] = 1
  98         };
  99
 100         if (state->pf != NFPROTO_IPV6)
 101                 return -NF_ACCEPT;
 102
 103         if (!nf_ct_is_confirmed(ct)) {
 104                 int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;
 105
 106                 if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
 107                         /* Can't create a new ICMPv6 `conn' with this. */
 108                         pr_debug("icmpv6: can't create new conn with type %u\n",
 109                                  type + 128);
 110                         nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
 111                         return -NF_ACCEPT;
 112                 }
 113         }
 114
 115         if (!timeout)
 116                 timeout = icmpv6_get_timeouts(nf_ct_net(ct));
 117
 118         /* Do not immediately delete the connection after the first
 119            successful reply to avoid excessive conntrackd traffic
 120            and also to handle correctly ICMP echo reply duplicates. */
 121         nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
 122
 123         return NF_ACCEPT;
 124 }
 125
 126
 127 static void icmpv6_error_log(const struct sk_buff *skb,
 128                              const struct nf_hook_state *state,
 129                              const char *msg)
 130 {
 131         nf_l4proto_log_invalid(skb, state->net, state->pf,
 132                                IPPROTO_ICMPV6, "%s", msg);
 133 }
 134
 135 int nf_conntrack_icmpv6_error(struct nf_conn *tmpl,
 136                               struct sk_buff *skb,
 137                               unsigned int dataoff,
 138                               const struct nf_hook_state *state)
 139 {
 140         union nf_inet_addr outer_daddr;
 141         const struct icmp6hdr *icmp6h;
 142         struct icmp6hdr _ih;
 143         int type;
 144
 145         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 146         if (icmp6h == NULL) {
 147                 icmpv6_error_log(skb, state, "short packet");
 148                 return -NF_ACCEPT;
 149         }
 150
 151         if (state->hook == NF_INET_PRE_ROUTING &&
 152             state->net->ct.sysctl_checksum &&
 153             nf_ip6_checksum(skb, state->hook, dataoff, IPPROTO_ICMPV6)) {
 154                 icmpv6_error_log(skb, state, "ICMPv6 checksum failed");
 155                 return -NF_ACCEPT;
 156         }
 157
 158         type = icmp6h->icmp6_type - 130;
 159         if (type >= 0 && type < sizeof(noct_valid_new) &&
 160             noct_valid_new[type]) {
 161                 nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
 162                 return NF_ACCEPT;
 163         }
 164
 165         /* is not error message ? */
 166         if (icmp6h->icmp6_type >= 128)
 167                 return NF_ACCEPT;
 168
 169         memcpy(&outer_daddr.ip6, &ipv6_hdr(skb)->daddr,
 170                sizeof(outer_daddr.ip6));
 171         dataoff += sizeof(*icmp6h);
 172         return nf_conntrack_inet_error(tmpl, skb, dataoff, state,
 173                                        IPPROTO_ICMPV6, &outer_daddr);
 174 }
 175
 176 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 177
 178 #include <linux/netfilter/nfnetlink.h>
 179 #include <linux/netfilter/nfnetlink_conntrack.h>
 180 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
 181                                   const struct nf_conntrack_tuple *t)
 182 {
 183         if (nla_put_be16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id) ||
 184             nla_put_u8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type) ||
 185             nla_put_u8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code))
 186                 goto nla_put_failure;
 187         return 0;
 188
 189 nla_put_failure:
 190         return -1;
 191 }
 192
 193 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
 194         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
 195         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
 196         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
 197 };
 198
 199 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
 200                                 struct nf_conntrack_tuple *tuple)
 201 {
 202         if (!tb[CTA_PROTO_ICMPV6_TYPE] ||
 203             !tb[CTA_PROTO_ICMPV6_CODE] ||
 204             !tb[CTA_PROTO_ICMPV6_ID])
 205                 return -EINVAL;
 206
 207         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
 208         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
 209         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
 210
 211         if (tuple->dst.u.icmp.type < 128 ||
 212             tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
 213             !invmap[tuple->dst.u.icmp.type - 128])
 214                 return -EINVAL;
 215
 216         return 0;
 217 }
 218
 219 static unsigned int icmpv6_nlattr_tuple_size(void)
 220 {
 221         static unsigned int size __read_mostly;
 222
 223         if (!size)
 224                 size = nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
 225
 226         return size;
 227 }
 228 #endif
 229
 230 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 231
 232 #include <linux/netfilter/nfnetlink.h>
 233 #include <linux/netfilter/nfnetlink_cttimeout.h>
 234
 235 static int icmpv6_timeout_nlattr_to_obj(struct nlattr *tb[],
 236                                         struct net *net, void *data)
 237 {
 238         unsigned int *timeout = data;
 239         struct nf_icmp_net *in = nf_icmpv6_pernet(net);
 240
 241         if (!timeout)
 242                 timeout = icmpv6_get_timeouts(net);
 243         if (tb[CTA_TIMEOUT_ICMPV6_TIMEOUT]) {
 244                 *timeout =
 245                     ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMPV6_TIMEOUT])) * HZ;
 246         } else {
 247                 /* Set default ICMPv6 timeout. */
 248                 *timeout = in->timeout;
 249         }
 250         return 0;
 251 }
 252
 253 static int
 254 icmpv6_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 255 {
 256         const unsigned int *timeout = data;
 257
 258         if (nla_put_be32(skb, CTA_TIMEOUT_ICMPV6_TIMEOUT, htonl(*timeout / HZ)))
 259                 goto nla_put_failure;
 260         return 0;
 261
 262 nla_put_failure:
 263         return -ENOSPC;
 264 }
 265
 266 static const struct nla_policy
 267 icmpv6_timeout_nla_policy[CTA_TIMEOUT_ICMPV6_MAX+1] = {
 268         [CTA_TIMEOUT_ICMPV6_TIMEOUT]    = { .type = NLA_U32 },
 269 };
 270 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 271
 272 void nf_conntrack_icmpv6_init_net(struct net *net)
 273 {
 274         struct nf_icmp_net *in = nf_icmpv6_pernet(net);
 275
 276         in->timeout = nf_ct_icmpv6_timeout;
 277 }
 278
 279 const struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 =
 280 {
 281         .l4proto                = IPPROTO_ICMPV6,
 282 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 283         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
 284         .nlattr_tuple_size      = icmpv6_nlattr_tuple_size,
 285         .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
 286         .nla_policy             = icmpv6_nla_policy,
 287 #endif
 288 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 289         .ctnl_timeout           = {
 290                 .nlattr_to_obj  = icmpv6_timeout_nlattr_to_obj,
 291                 .obj_to_nlattr  = icmpv6_timeout_obj_to_nlattr,
 292                 .nlattr_max     = CTA_TIMEOUT_ICMP_MAX,
 293                 .obj_size       = sizeof(unsigned int),
 294                 .nla_policy     = icmpv6_timeout_nla_policy,
 295         },
 296 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 297 };