linux/net/netfilter/nf_conntrack_proto_icmpv6.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright (C)2003,2004 USAGI/WIDE Project
   4 *
   5 * Author:
   6 *      Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
   7 */
   8
   9#include <linux/types.h>
  10#include <linux/timer.h>
  11#include <linux/module.h>
  12#include <linux/netfilter.h>
  13#include <linux/in6.h>
  14#include <linux/icmpv6.h>
  15#include <linux/ipv6.h>
  16#include <net/ipv6.h>
  17#include <net/ip6_checksum.h>
  18#include <linux/seq_file.h>
  19#include <linux/netfilter_ipv6.h>
  20#include <net/netfilter/nf_conntrack_tuple.h>
  21#include <net/netfilter/nf_conntrack_l4proto.h>
  22#include <net/netfilter/nf_conntrack_core.h>
  23#include <net/netfilter/nf_conntrack_timeout.h>
  24#include <net/netfilter/nf_conntrack_zones.h>
  25#include <net/netfilter/ipv6/nf_conntrack_icmpv6.h>
  26#include <net/netfilter/nf_log.h>
  27
  28static const unsigned int nf_ct_icmpv6_timeout = 30*HZ;
  29
  30bool icmpv6_pkt_to_tuple(const struct sk_buff *skb,
  31                         unsigned int dataoff,
  32                         struct net *net,
  33                         struct nf_conntrack_tuple *tuple)
  34{
  35        const struct icmp6hdr *hp;
  36        struct icmp6hdr _hdr;
  37
  38        hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  39        if (hp == NULL)
  40                return false;
  41        tuple->dst.u.icmp.type = hp->icmp6_type;
  42        tuple->src.u.icmp.id = hp->icmp6_identifier;
  43        tuple->dst.u.icmp.code = hp->icmp6_code;
  44
  45        return true;
  46}
  47
  48/* Add 1; spaces filled with 0. */
  49static const u_int8_t invmap[] = {
  50        [ICMPV6_ECHO_REQUEST - 128]     = ICMPV6_ECHO_REPLY + 1,
  51        [ICMPV6_ECHO_REPLY - 128]       = ICMPV6_ECHO_REQUEST + 1,
  52        [ICMPV6_NI_QUERY - 128]         = ICMPV6_NI_REPLY + 1,
  53        [ICMPV6_NI_REPLY - 128]         = ICMPV6_NI_QUERY + 1
  54};
  55
  56static const u_int8_t noct_valid_new[] = {
  57        [ICMPV6_MGM_QUERY - 130] = 1,
  58        [ICMPV6_MGM_REPORT - 130] = 1,
  59        [ICMPV6_MGM_REDUCTION - 130] = 1,
  60        [NDISC_ROUTER_SOLICITATION - 130] = 1,
  61        [NDISC_ROUTER_ADVERTISEMENT - 130] = 1,
  62        [NDISC_NEIGHBOUR_SOLICITATION - 130] = 1,
  63        [NDISC_NEIGHBOUR_ADVERTISEMENT - 130] = 1,
  64        [ICMPV6_MLD2_REPORT - 130] = 1
  65};
  66
  67bool nf_conntrack_invert_icmpv6_tuple(struct nf_conntrack_tuple *tuple,
  68                                      const struct nf_conntrack_tuple *orig)
  69{
  70        int type = orig->dst.u.icmp.type - 128;
  71        if (type < 0 || type >= sizeof(invmap) || !invmap[type])
  72                return false;
  73
  74        tuple->src.u.icmp.id   = orig->src.u.icmp.id;
  75        tuple->dst.u.icmp.type = invmap[type] - 1;
  76        tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
  77        return true;
  78}
  79
  80static unsigned int *icmpv6_get_timeouts(struct net *net)
  81{
  82        return &nf_icmpv6_pernet(net)->timeout;
  83}
  84
  85/* Returns verdict for packet, or -1 for invalid. */
  86int nf_conntrack_icmpv6_packet(struct nf_conn *ct,
  87                               struct sk_buff *skb,
  88                               enum ip_conntrack_info ctinfo,
  89                               const struct nf_hook_state *state)
  90{
  91        unsigned int *timeout = nf_ct_timeout_lookup(ct);
  92        static const u8 valid_new[] = {
  93                [ICMPV6_ECHO_REQUEST - 128] = 1,
  94                [ICMPV6_NI_QUERY - 128] = 1
  95        };
  96
  97        if (state->pf != NFPROTO_IPV6)
  98                return -NF_ACCEPT;
  99
 100        if (!nf_ct_is_confirmed(ct)) {
 101                int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;
 102
 103                if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
 104                        /* Can't create a new ICMPv6 `conn' with this. */
 105                        pr_debug("icmpv6: can't create new conn with type %u\n",
 106                                 type + 128);
 107                        nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
 108                        return -NF_ACCEPT;
 109                }
 110        }
 111
 112        if (!timeout)
 113                timeout = icmpv6_get_timeouts(nf_ct_net(ct));
 114
 115        /* Do not immediately delete the connection after the first
 116           successful reply to avoid excessive conntrackd traffic
 117           and also to handle correctly ICMP echo reply duplicates. */
 118        nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
 119
 120        return NF_ACCEPT;
 121}
 122
 123
 124static void icmpv6_error_log(const struct sk_buff *skb,
 125                             const struct nf_hook_state *state,
 126                             const char *msg)
 127{
 128        nf_l4proto_log_invalid(skb, state->net, state->pf,
 129                               IPPROTO_ICMPV6, "%s", msg);
 130}
 131
 132int nf_conntrack_icmpv6_error(struct nf_conn *tmpl,
 133                              struct sk_buff *skb,
 134                              unsigned int dataoff,
 135                              const struct nf_hook_state *state)
 136{
 137        union nf_inet_addr outer_daddr;
 138        const struct icmp6hdr *icmp6h;
 139        struct icmp6hdr _ih;
 140        int type;
 141
 142        icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 143        if (icmp6h == NULL) {
 144                icmpv6_error_log(skb, state, "short packet");
 145                return -NF_ACCEPT;
 146        }
 147
 148        if (state->hook == NF_INET_PRE_ROUTING &&
 149            state->net->ct.sysctl_checksum &&
 150            nf_ip6_checksum(skb, state->hook, dataoff, IPPROTO_ICMPV6)) {
 151                icmpv6_error_log(skb, state, "ICMPv6 checksum failed");
 152                return -NF_ACCEPT;
 153        }
 154
 155        type = icmp6h->icmp6_type - 130;
 156        if (type >= 0 && type < sizeof(noct_valid_new) &&
 157            noct_valid_new[type]) {
 158                nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
 159                return NF_ACCEPT;
 160        }
 161
 162        /* is not error message ? */
 163        if (icmp6h->icmp6_type >= 128)
 164                return NF_ACCEPT;
 165
 166        memcpy(&outer_daddr.ip6, &ipv6_hdr(skb)->daddr,
 167               sizeof(outer_daddr.ip6));
 168        dataoff += sizeof(*icmp6h);
 169        return nf_conntrack_inet_error(tmpl, skb, dataoff, state,
 170                                       IPPROTO_ICMPV6, &outer_daddr);
 171}
 172
 173#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 174
 175#include <linux/netfilter/nfnetlink.h>
 176#include <linux/netfilter/nfnetlink_conntrack.h>
 177static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
 178                                  const struct nf_conntrack_tuple *t)
 179{
 180        if (nla_put_be16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id) ||
 181            nla_put_u8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type) ||
 182            nla_put_u8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code))
 183                goto nla_put_failure;
 184        return 0;
 185
 186nla_put_failure:
 187        return -1;
 188}
 189
 190static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
 191        [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
 192        [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
 193        [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
 194};
 195
 196static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
 197                                struct nf_conntrack_tuple *tuple)
 198{
 199        if (!tb[CTA_PROTO_ICMPV6_TYPE] ||
 200            !tb[CTA_PROTO_ICMPV6_CODE] ||
 201            !tb[CTA_PROTO_ICMPV6_ID])
 202                return -EINVAL;
 203
 204        tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
 205        tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
 206        tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
 207
 208        if (tuple->dst.u.icmp.type < 128 ||
 209            tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
 210            !invmap[tuple->dst.u.icmp.type - 128])
 211                return -EINVAL;
 212
 213        return 0;
 214}
 215
 216static unsigned int icmpv6_nlattr_tuple_size(void)
 217{
 218        static unsigned int size __read_mostly;
 219
 220        if (!size)
 221                size = nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
 222
 223        return size;
 224}
 225#endif
 226
 227#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 228
 229#include <linux/netfilter/nfnetlink.h>
 230#include <linux/netfilter/nfnetlink_cttimeout.h>
 231
 232static int icmpv6_timeout_nlattr_to_obj(struct nlattr *tb[],
 233                                        struct net *net, void *data)
 234{
 235        unsigned int *timeout = data;
 236        struct nf_icmp_net *in = nf_icmpv6_pernet(net);
 237
 238        if (!timeout)
 239                timeout = icmpv6_get_timeouts(net);
 240        if (tb[CTA_TIMEOUT_ICMPV6_TIMEOUT]) {
 241                *timeout =
 242                    ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMPV6_TIMEOUT])) * HZ;
 243        } else {
 244                /* Set default ICMPv6 timeout. */
 245                *timeout = in->timeout;
 246        }
 247        return 0;
 248}
 249
 250static int
 251icmpv6_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 252{
 253        const unsigned int *timeout = data;
 254
 255        if (nla_put_be32(skb, CTA_TIMEOUT_ICMPV6_TIMEOUT, htonl(*timeout / HZ)))
 256                goto nla_put_failure;
 257        return 0;
 258
 259nla_put_failure:
 260        return -ENOSPC;
 261}
 262
 263static const struct nla_policy
 264icmpv6_timeout_nla_policy[CTA_TIMEOUT_ICMPV6_MAX+1] = {
 265        [CTA_TIMEOUT_ICMPV6_TIMEOUT]    = { .type = NLA_U32 },
 266};
 267#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 268
 269void nf_conntrack_icmpv6_init_net(struct net *net)
 270{
 271        struct nf_icmp_net *in = nf_icmpv6_pernet(net);
 272
 273        in->timeout = nf_ct_icmpv6_timeout;
 274}
 275
 276const struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 =
 277{
 278        .l4proto                = IPPROTO_ICMPV6,
 279#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 280        .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
 281        .nlattr_tuple_size      = icmpv6_nlattr_tuple_size,
 282        .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
 283        .nla_policy             = icmpv6_nla_policy,
 284#endif
 285#ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 286        .ctnl_timeout           = {
 287                .nlattr_to_obj  = icmpv6_timeout_nlattr_to_obj,
 288                .obj_to_nlattr  = icmpv6_timeout_obj_to_nlattr,
 289                .nlattr_max     = CTA_TIMEOUT_ICMP_MAX,
 290                .obj_size       = sizeof(unsigned int),
 291                .nla_policy     = icmpv6_timeout_nla_policy,
 292        },
 293#endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 294};
 295