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, IPPROTO_ICMPV6, "%s", msg);
 130 }
 131
 132 static noinline_for_stack int
 133 nf_conntrack_icmpv6_redirect(struct nf_conn *tmpl, struct sk_buff *skb,
 134                              unsigned int dataoff,
 135                              const struct nf_hook_state *state)
 136 {
 137         u8 hl = ipv6_hdr(skb)->hop_limit;
 138         union nf_inet_addr outer_daddr;
 139         union {
 140                 struct nd_opt_hdr nd_opt;
 141                 struct rd_msg rd_msg;
 142         } tmp;
 143         const struct nd_opt_hdr *nd_opt;
 144         const struct rd_msg *rd_msg;
 145
 146         rd_msg = skb_header_pointer(skb, dataoff, sizeof(*rd_msg), &tmp.rd_msg);
 147         if (!rd_msg) {
 148                 icmpv6_error_log(skb, state, "short redirect");
 149                 return -NF_ACCEPT;
 150         }
 151
 152         if (rd_msg->icmph.icmp6_code != 0)
 153                 return NF_ACCEPT;
 154
 155         if (hl != 255 || !(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL)) {
 156                 icmpv6_error_log(skb, state, "invalid saddr or hoplimit for redirect");
 157                 return -NF_ACCEPT;
 158         }
 159
 160         dataoff += sizeof(*rd_msg);
 161
 162         /* warning: rd_msg no longer usable after this call */
 163         nd_opt = skb_header_pointer(skb, dataoff, sizeof(*nd_opt), &tmp.nd_opt);
 164         if (!nd_opt || nd_opt->nd_opt_len == 0) {
 165                 icmpv6_error_log(skb, state, "redirect without options");
 166                 return -NF_ACCEPT;
 167         }
 168
 169         /* We could call ndisc_parse_options(), but it would need
 170          * skb_linearize() and a bit more work.
 171          */
 172         if (nd_opt->nd_opt_type != ND_OPT_REDIRECT_HDR)
 173                 return NF_ACCEPT;
 174
 175         memcpy(&outer_daddr.ip6, &ipv6_hdr(skb)->daddr,
 176                sizeof(outer_daddr.ip6));
 177         dataoff += 8;
 178         return nf_conntrack_inet_error(tmpl, skb, dataoff, state,
 179                                        IPPROTO_ICMPV6, &outer_daddr);
 180 }
 181
 182 int nf_conntrack_icmpv6_error(struct nf_conn *tmpl,
 183                               struct sk_buff *skb,
 184                               unsigned int dataoff,
 185                               const struct nf_hook_state *state)
 186 {
 187         union nf_inet_addr outer_daddr;
 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                 icmpv6_error_log(skb, state, "short packet");
 195                 return -NF_ACCEPT;
 196         }
 197
 198         if (state->hook == NF_INET_PRE_ROUTING &&
 199             state->net->ct.sysctl_checksum &&
 200             nf_ip6_checksum(skb, state->hook, dataoff, IPPROTO_ICMPV6)) {
 201                 icmpv6_error_log(skb, state, "ICMPv6 checksum failed");
 202                 return -NF_ACCEPT;
 203         }
 204
 205         type = icmp6h->icmp6_type - 130;
 206         if (type >= 0 && type < sizeof(noct_valid_new) &&
 207             noct_valid_new[type]) {
 208                 nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
 209                 return NF_ACCEPT;
 210         }
 211
 212         if (icmp6h->icmp6_type == NDISC_REDIRECT)
 213                 return nf_conntrack_icmpv6_redirect(tmpl, skb, dataoff, state);
 214
 215         /* is not error message ? */
 216         if (icmp6h->icmp6_type >= 128)
 217                 return NF_ACCEPT;
 218
 219         memcpy(&outer_daddr.ip6, &ipv6_hdr(skb)->daddr,
 220                sizeof(outer_daddr.ip6));
 221         dataoff += sizeof(*icmp6h);
 222         return nf_conntrack_inet_error(tmpl, skb, dataoff, state,
 223                                        IPPROTO_ICMPV6, &outer_daddr);
 224 }
 225
 226 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 227
 228 #include <linux/netfilter/nfnetlink.h>
 229 #include <linux/netfilter/nfnetlink_conntrack.h>
 230 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
 231                                   const struct nf_conntrack_tuple *t)
 232 {
 233         if (nla_put_be16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id) ||
 234             nla_put_u8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type) ||
 235             nla_put_u8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code))
 236                 goto nla_put_failure;
 237         return 0;
 238
 239 nla_put_failure:
 240         return -1;
 241 }
 242
 243 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
 244         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
 245         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
 246         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
 247 };
 248
 249 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
 250                                 struct nf_conntrack_tuple *tuple,
 251                                 u_int32_t flags)
 252 {
 253         if (flags & CTA_FILTER_FLAG(CTA_PROTO_ICMPV6_TYPE)) {
 254                 if (!tb[CTA_PROTO_ICMPV6_TYPE])
 255                         return -EINVAL;
 256
 257                 tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
 258                 if (tuple->dst.u.icmp.type < 128 ||
 259                     tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
 260                     !invmap[tuple->dst.u.icmp.type - 128])
 261                         return -EINVAL;
 262         }
 263
 264         if (flags & CTA_FILTER_FLAG(CTA_PROTO_ICMPV6_CODE)) {
 265                 if (!tb[CTA_PROTO_ICMPV6_CODE])
 266                         return -EINVAL;
 267
 268                 tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
 269         }
 270
 271         if (flags & CTA_FILTER_FLAG(CTA_PROTO_ICMPV6_ID)) {
 272                 if (!tb[CTA_PROTO_ICMPV6_ID])
 273                         return -EINVAL;
 274
 275                 tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
 276         }
 277
 278         return 0;
 279 }
 280
 281 static unsigned int icmpv6_nlattr_tuple_size(void)
 282 {
 283         static unsigned int size __read_mostly;
 284
 285         if (!size)
 286                 size = nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
 287
 288         return size;
 289 }
 290 #endif
 291
 292 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 293
 294 #include <linux/netfilter/nfnetlink.h>
 295 #include <linux/netfilter/nfnetlink_cttimeout.h>
 296
 297 static int icmpv6_timeout_nlattr_to_obj(struct nlattr *tb[],
 298                                         struct net *net, void *data)
 299 {
 300         unsigned int *timeout = data;
 301         struct nf_icmp_net *in = nf_icmpv6_pernet(net);
 302
 303         if (!timeout)
 304                 timeout = icmpv6_get_timeouts(net);
 305         if (tb[CTA_TIMEOUT_ICMPV6_TIMEOUT]) {
 306                 *timeout =
 307                     ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMPV6_TIMEOUT])) * HZ;
 308         } else {
 309                 /* Set default ICMPv6 timeout. */
 310                 *timeout = in->timeout;
 311         }
 312         return 0;
 313 }
 314
 315 static int
 316 icmpv6_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 317 {
 318         const unsigned int *timeout = data;
 319
 320         if (nla_put_be32(skb, CTA_TIMEOUT_ICMPV6_TIMEOUT, htonl(*timeout / HZ)))
 321                 goto nla_put_failure;
 322         return 0;
 323
 324 nla_put_failure:
 325         return -ENOSPC;
 326 }
 327
 328 static const struct nla_policy
 329 icmpv6_timeout_nla_policy[CTA_TIMEOUT_ICMPV6_MAX+1] = {
 330         [CTA_TIMEOUT_ICMPV6_TIMEOUT]    = { .type = NLA_U32 },
 331 };
 332 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 333
 334 void nf_conntrack_icmpv6_init_net(struct net *net)
 335 {
 336         struct nf_icmp_net *in = nf_icmpv6_pernet(net);
 337
 338         in->timeout = nf_ct_icmpv6_timeout;
 339 }
 340
 341 const struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 =
 342 {
 343         .l4proto                = IPPROTO_ICMPV6,
 344 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 345         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
 346         .nlattr_tuple_size      = icmpv6_nlattr_tuple_size,
 347         .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
 348         .nla_policy             = icmpv6_nla_policy,
 349 #endif
 350 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 351         .ctnl_timeout           = {
 352                 .nlattr_to_obj  = icmpv6_timeout_nlattr_to_obj,
 353                 .obj_to_nlattr  = icmpv6_timeout_obj_to_nlattr,
 354                 .nlattr_max     = CTA_TIMEOUT_ICMP_MAX,
 355                 .obj_size       = sizeof(unsigned int),
 356                 .nla_policy     = icmpv6_timeout_nla_policy,
 357         },
 358 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 359 };