net/netfilter/nf_conntrack_proto_icmpv6.c

   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/nf_log.h>
  26
  27 #include "nf_internals.h"
  28
  29 static const unsigned int nf_ct_icmpv6_timeout = 30*HZ;
  30
  31 bool icmpv6_pkt_to_tuple(const struct sk_buff *skb,
  32                          unsigned int dataoff,
  33                          struct net *net,
  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 bool nf_conntrack_invert_icmpv6_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 static unsigned int *icmpv6_get_timeouts(struct net *net)
  82 {
  83         return &nf_icmpv6_pernet(net)->timeout;
  84 }
  85
  86 /* Returns verdict for packet, or -1 for invalid. */
  87 int nf_conntrack_icmpv6_packet(struct nf_conn *ct,
  88                                struct sk_buff *skb,
  89                                enum ip_conntrack_info ctinfo,
  90                                const struct nf_hook_state *state)
  91 {
  92         unsigned int *timeout = nf_ct_timeout_lookup(ct);
  93         static const u8 valid_new[] = {
  94                 [ICMPV6_ECHO_REQUEST - 128] = 1,
  95                 [ICMPV6_NI_QUERY - 128] = 1
  96         };
  97
  98         if (state->pf != NFPROTO_IPV6)
  99                 return -NF_ACCEPT;
 100
 101         if (!nf_ct_is_confirmed(ct)) {
 102                 int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;
 103
 104                 if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
 105                         /* Can't create a new ICMPv6 `conn' with this. */
 106                         pr_debug("icmpv6: can't create new conn with type %u\n",
 107                                  type + 128);
 108                         nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
 109                         return -NF_ACCEPT;
 110                 }
 111         }
 112
 113         if (!timeout)
 114                 timeout = icmpv6_get_timeouts(nf_ct_net(ct));
 115
 116         /* Do not immediately delete the connection after the first
 117            successful reply to avoid excessive conntrackd traffic
 118            and also to handle correctly ICMP echo reply duplicates. */
 119         nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
 120
 121         return NF_ACCEPT;
 122 }
 123
 124
 125 static void icmpv6_error_log(const struct sk_buff *skb,
 126                              const struct nf_hook_state *state,
 127                              const char *msg)
 128 {
 129         nf_l4proto_log_invalid(skb, state->net, state->pf,
 130                                IPPROTO_ICMPV6, "%s", msg);
 131 }
 132
 133 int nf_conntrack_icmpv6_error(struct nf_conn *tmpl,
 134                               struct sk_buff *skb,
 135                               unsigned int dataoff,
 136                               const struct nf_hook_state *state)
 137 {
 138         union nf_inet_addr outer_daddr;
 139         const struct icmp6hdr *icmp6h;
 140         struct icmp6hdr _ih;
 141         int type;
 142
 143         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 144         if (icmp6h == NULL) {
 145                 icmpv6_error_log(skb, state, "short packet");
 146                 return -NF_ACCEPT;
 147         }
 148
 149         if (state->hook == NF_INET_PRE_ROUTING &&
 150             state->net->ct.sysctl_checksum &&
 151             nf_ip6_checksum(skb, state->hook, dataoff, IPPROTO_ICMPV6)) {
 152                 icmpv6_error_log(skb, state, "ICMPv6 checksum failed");
 153                 return -NF_ACCEPT;
 154         }
 155
 156         type = icmp6h->icmp6_type - 130;
 157         if (type >= 0 && type < sizeof(noct_valid_new) &&
 158             noct_valid_new[type]) {
 159                 nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
 160                 return NF_ACCEPT;
 161         }
 162
 163         /* is not error message ? */
 164         if (icmp6h->icmp6_type >= 128)
 165                 return NF_ACCEPT;
 166
 167         memcpy(&outer_daddr.ip6, &ipv6_hdr(skb)->daddr,
 168                sizeof(outer_daddr.ip6));
 169         dataoff += sizeof(*icmp6h);
 170         return nf_conntrack_inet_error(tmpl, skb, dataoff, state,
 171                                        IPPROTO_ICMPV6, &outer_daddr);
 172 }
 173
 174 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 175
 176 #include <linux/netfilter/nfnetlink.h>
 177 #include <linux/netfilter/nfnetlink_conntrack.h>
 178 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
 179                                   const struct nf_conntrack_tuple *t)
 180 {
 181         if (nla_put_be16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id) ||
 182             nla_put_u8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type) ||
 183             nla_put_u8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code))
 184                 goto nla_put_failure;
 185         return 0;
 186
 187 nla_put_failure:
 188         return -1;
 189 }
 190
 191 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
 192         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
 193         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
 194         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
 195 };
 196
 197 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
 198                                 struct nf_conntrack_tuple *tuple,
 199                                 u_int32_t flags)
 200 {
 201         if (flags & CTA_FILTER_FLAG(CTA_PROTO_ICMPV6_TYPE)) {
 202                 if (!tb[CTA_PROTO_ICMPV6_TYPE])
 203                         return -EINVAL;
 204
 205                 tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
 206                 if (tuple->dst.u.icmp.type < 128 ||
 207                     tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
 208                     !invmap[tuple->dst.u.icmp.type - 128])
 209                         return -EINVAL;
 210         }
 211
 212         if (flags & CTA_FILTER_FLAG(CTA_PROTO_ICMPV6_CODE)) {
 213                 if (!tb[CTA_PROTO_ICMPV6_CODE])
 214                         return -EINVAL;
 215
 216                 tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
 217         }
 218
 219         if (flags & CTA_FILTER_FLAG(CTA_PROTO_ICMPV6_ID)) {
 220                 if (!tb[CTA_PROTO_ICMPV6_ID])
 221                         return -EINVAL;
 222
 223                 tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
 224         }
 225
 226         return 0;
 227 }
 228
 229 static unsigned int icmpv6_nlattr_tuple_size(void)
 230 {
 231         static unsigned int size __read_mostly;
 232
 233         if (!size)
 234                 size = nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
 235
 236         return size;
 237 }
 238 #endif
 239
 240 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 241
 242 #include <linux/netfilter/nfnetlink.h>
 243 #include <linux/netfilter/nfnetlink_cttimeout.h>
 244
 245 static int icmpv6_timeout_nlattr_to_obj(struct nlattr *tb[],
 246                                         struct net *net, void *data)
 247 {
 248         unsigned int *timeout = data;
 249         struct nf_icmp_net *in = nf_icmpv6_pernet(net);
 250
 251         if (!timeout)
 252                 timeout = icmpv6_get_timeouts(net);
 253         if (tb[CTA_TIMEOUT_ICMPV6_TIMEOUT]) {
 254                 *timeout =
 255                     ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMPV6_TIMEOUT])) * HZ;
 256         } else {
 257                 /* Set default ICMPv6 timeout. */
 258                 *timeout = in->timeout;
 259         }
 260         return 0;
 261 }
 262
 263 static int
 264 icmpv6_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 265 {
 266         const unsigned int *timeout = data;
 267
 268         if (nla_put_be32(skb, CTA_TIMEOUT_ICMPV6_TIMEOUT, htonl(*timeout / HZ)))
 269                 goto nla_put_failure;
 270         return 0;
 271
 272 nla_put_failure:
 273         return -ENOSPC;
 274 }
 275
 276 static const struct nla_policy
 277 icmpv6_timeout_nla_policy[CTA_TIMEOUT_ICMPV6_MAX+1] = {
 278         [CTA_TIMEOUT_ICMPV6_TIMEOUT]    = { .type = NLA_U32 },
 279 };
 280 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 281
 282 void nf_conntrack_icmpv6_init_net(struct net *net)
 283 {
 284         struct nf_icmp_net *in = nf_icmpv6_pernet(net);
 285
 286         in->timeout = nf_ct_icmpv6_timeout;
 287 }
 288
 289 const struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 =
 290 {
 291         .l4proto                = IPPROTO_ICMPV6,
 292 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 293         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
 294         .nlattr_tuple_size      = icmpv6_nlattr_tuple_size,
 295         .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
 296         .nla_policy             = icmpv6_nla_policy,
 297 #endif
 298 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 299         .ctnl_timeout           = {
 300                 .nlattr_to_obj  = icmpv6_timeout_nlattr_to_obj,
 301                 .obj_to_nlattr  = icmpv6_timeout_obj_to_nlattr,
 302                 .nlattr_max     = CTA_TIMEOUT_ICMP_MAX,
 303                 .obj_size       = sizeof(unsigned int),
 304                 .nla_policy     = icmpv6_timeout_nla_policy,
 305         },
 306 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 307 };