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 static int
 127 icmpv6_error_message(struct net *net, struct nf_conn *tmpl,
 128                      struct sk_buff *skb,
 129                      unsigned int icmp6off)
 130 {
 131         struct nf_conntrack_tuple intuple, origtuple;
 132         const struct nf_conntrack_tuple_hash *h;
 133         enum ip_conntrack_info ctinfo;
 134         struct nf_conntrack_zone tmp;
 135
 136         WARN_ON(skb_nfct(skb));
 137
 138         /* Are they talking about one of our connections? */
 139         if (!nf_ct_get_tuplepr(skb,
 140                                skb_network_offset(skb)
 141                                 + sizeof(struct ipv6hdr)
 142                                 + sizeof(struct icmp6hdr),
 143                                PF_INET6, net, &origtuple)) {
 144                 pr_debug("icmpv6_error: Can't get tuple\n");
 145                 return -NF_ACCEPT;
 146         }
 147
 148         /* Ordinarily, we'd expect the inverted tupleproto, but it's
 149            been preserved inside the ICMP. */
 150         if (!nf_ct_invert_tuple(&intuple, &origtuple)) {
 151                 pr_debug("icmpv6_error: Can't invert tuple\n");
 152                 return -NF_ACCEPT;
 153         }
 154
 155         ctinfo = IP_CT_RELATED;
 156
 157         h = nf_conntrack_find_get(net, nf_ct_zone_tmpl(tmpl, skb, &tmp),
 158                                   &intuple);
 159         if (!h) {
 160                 pr_debug("icmpv6_error: no match\n");
 161                 return -NF_ACCEPT;
 162         } else {
 163                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
 164                         ctinfo += IP_CT_IS_REPLY;
 165         }
 166
 167         /* Update skb to refer to this connection */
 168         nf_ct_set(skb, nf_ct_tuplehash_to_ctrack(h), ctinfo);
 169         return NF_ACCEPT;
 170 }
 171
 172 static void icmpv6_error_log(const struct sk_buff *skb,
 173                              const struct nf_hook_state *state,
 174                              const char *msg)
 175 {
 176         nf_l4proto_log_invalid(skb, state->net, state->pf,
 177                                IPPROTO_ICMPV6, "%s", msg);
 178 }
 179
 180 int nf_conntrack_icmpv6_error(struct nf_conn *tmpl,
 181                               struct sk_buff *skb,
 182                               unsigned int dataoff,
 183                               const struct nf_hook_state *state)
 184 {
 185         const struct icmp6hdr *icmp6h;
 186         struct icmp6hdr _ih;
 187         int type;
 188
 189         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 190         if (icmp6h == NULL) {
 191                 icmpv6_error_log(skb, state, "short packet");
 192                 return -NF_ACCEPT;
 193         }
 194
 195         if (state->hook == NF_INET_PRE_ROUTING &&
 196             state->net->ct.sysctl_checksum &&
 197             nf_ip6_checksum(skb, state->hook, dataoff, IPPROTO_ICMPV6)) {
 198                 icmpv6_error_log(skb, state, "ICMPv6 checksum failed");
 199                 return -NF_ACCEPT;
 200         }
 201
 202         type = icmp6h->icmp6_type - 130;
 203         if (type >= 0 && type < sizeof(noct_valid_new) &&
 204             noct_valid_new[type]) {
 205                 nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
 206                 return NF_ACCEPT;
 207         }
 208
 209         /* is not error message ? */
 210         if (icmp6h->icmp6_type >= 128)
 211                 return NF_ACCEPT;
 212
 213         return icmpv6_error_message(state->net, tmpl, skb, dataoff);
 214 }
 215
 216 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 217
 218 #include <linux/netfilter/nfnetlink.h>
 219 #include <linux/netfilter/nfnetlink_conntrack.h>
 220 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
 221                                   const struct nf_conntrack_tuple *t)
 222 {
 223         if (nla_put_be16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id) ||
 224             nla_put_u8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type) ||
 225             nla_put_u8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code))
 226                 goto nla_put_failure;
 227         return 0;
 228
 229 nla_put_failure:
 230         return -1;
 231 }
 232
 233 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
 234         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
 235         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
 236         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
 237 };
 238
 239 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
 240                                 struct nf_conntrack_tuple *tuple)
 241 {
 242         if (!tb[CTA_PROTO_ICMPV6_TYPE] ||
 243             !tb[CTA_PROTO_ICMPV6_CODE] ||
 244             !tb[CTA_PROTO_ICMPV6_ID])
 245                 return -EINVAL;
 246
 247         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
 248         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
 249         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
 250
 251         if (tuple->dst.u.icmp.type < 128 ||
 252             tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
 253             !invmap[tuple->dst.u.icmp.type - 128])
 254                 return -EINVAL;
 255
 256         return 0;
 257 }
 258
 259 static unsigned int icmpv6_nlattr_tuple_size(void)
 260 {
 261         static unsigned int size __read_mostly;
 262
 263         if (!size)
 264                 size = nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
 265
 266         return size;
 267 }
 268 #endif
 269
 270 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 271
 272 #include <linux/netfilter/nfnetlink.h>
 273 #include <linux/netfilter/nfnetlink_cttimeout.h>
 274
 275 static int icmpv6_timeout_nlattr_to_obj(struct nlattr *tb[],
 276                                         struct net *net, void *data)
 277 {
 278         unsigned int *timeout = data;
 279         struct nf_icmp_net *in = nf_icmpv6_pernet(net);
 280
 281         if (!timeout)
 282                 timeout = icmpv6_get_timeouts(net);
 283         if (tb[CTA_TIMEOUT_ICMPV6_TIMEOUT]) {
 284                 *timeout =
 285                     ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMPV6_TIMEOUT])) * HZ;
 286         } else {
 287                 /* Set default ICMPv6 timeout. */
 288                 *timeout = in->timeout;
 289         }
 290         return 0;
 291 }
 292
 293 static int
 294 icmpv6_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 295 {
 296         const unsigned int *timeout = data;
 297
 298         if (nla_put_be32(skb, CTA_TIMEOUT_ICMPV6_TIMEOUT, htonl(*timeout / HZ)))
 299                 goto nla_put_failure;
 300         return 0;
 301
 302 nla_put_failure:
 303         return -ENOSPC;
 304 }
 305
 306 static const struct nla_policy
 307 icmpv6_timeout_nla_policy[CTA_TIMEOUT_ICMPV6_MAX+1] = {
 308         [CTA_TIMEOUT_ICMPV6_TIMEOUT]    = { .type = NLA_U32 },
 309 };
 310 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 311
 312 void nf_conntrack_icmpv6_init_net(struct net *net)
 313 {
 314         struct nf_icmp_net *in = nf_icmpv6_pernet(net);
 315
 316         in->timeout = nf_ct_icmpv6_timeout;
 317 }
 318
 319 const struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 =
 320 {
 321         .l4proto                = IPPROTO_ICMPV6,
 322 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 323         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
 324         .nlattr_tuple_size      = icmpv6_nlattr_tuple_size,
 325         .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
 326         .nla_policy             = icmpv6_nla_policy,
 327 #endif
 328 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 329         .ctnl_timeout           = {
 330                 .nlattr_to_obj  = icmpv6_timeout_nlattr_to_obj,
 331                 .obj_to_nlattr  = icmpv6_timeout_obj_to_nlattr,
 332                 .nlattr_max     = CTA_TIMEOUT_ICMP_MAX,
 333                 .obj_size       = sizeof(unsigned int),
 334                 .nla_policy     = icmpv6_timeout_nla_policy,
 335         },
 336 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 337 };