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 static 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 static bool icmpv6_invert_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 static int icmpv6_packet(struct nf_conn *ct,
  90                          struct sk_buff *skb,
  91                          unsigned int dataoff,
  92                          enum ip_conntrack_info ctinfo,
  93                          const struct nf_hook_state *state)
  94 {
  95         unsigned int *timeout = nf_ct_timeout_lookup(ct);
  96         static const u8 valid_new[] = {
  97                 [ICMPV6_ECHO_REQUEST - 128] = 1,
  98                 [ICMPV6_NI_QUERY - 128] = 1
  99         };
 100
 101         if (state->pf != NFPROTO_IPV6)
 102                 return -NF_ACCEPT;
 103
 104         if (!nf_ct_is_confirmed(ct)) {
 105                 int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;
 106
 107                 if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
 108                         /* Can't create a new ICMPv6 `conn' with this. */
 109                         pr_debug("icmpv6: can't create new conn with type %u\n",
 110                                  type + 128);
 111                         nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
 112                         return -NF_ACCEPT;
 113                 }
 114         }
 115
 116         if (!timeout)
 117                 timeout = icmpv6_get_timeouts(nf_ct_net(ct));
 118
 119         /* Do not immediately delete the connection after the first
 120            successful reply to avoid excessive conntrackd traffic
 121            and also to handle correctly ICMP echo reply duplicates. */
 122         nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
 123
 124         return NF_ACCEPT;
 125 }
 126
 127 static int
 128 icmpv6_error_message(struct net *net, struct nf_conn *tmpl,
 129                      struct sk_buff *skb,
 130                      unsigned int icmp6off)
 131 {
 132         struct nf_conntrack_tuple intuple, origtuple;
 133         const struct nf_conntrack_tuple_hash *h;
 134         const struct nf_conntrack_l4proto *inproto;
 135         enum ip_conntrack_info ctinfo;
 136         struct nf_conntrack_zone tmp;
 137
 138         WARN_ON(skb_nfct(skb));
 139
 140         /* Are they talking about one of our connections? */
 141         if (!nf_ct_get_tuplepr(skb,
 142                                skb_network_offset(skb)
 143                                 + sizeof(struct ipv6hdr)
 144                                 + sizeof(struct icmp6hdr),
 145                                PF_INET6, net, &origtuple)) {
 146                 pr_debug("icmpv6_error: Can't get tuple\n");
 147                 return -NF_ACCEPT;
 148         }
 149
 150         /* rcu_read_lock()ed by nf_hook_thresh */
 151         inproto = __nf_ct_l4proto_find(origtuple.dst.protonum);
 152
 153         /* Ordinarily, we'd expect the inverted tupleproto, but it's
 154            been preserved inside the ICMP. */
 155         if (!nf_ct_invert_tuple(&intuple, &origtuple, inproto)) {
 156                 pr_debug("icmpv6_error: Can't invert tuple\n");
 157                 return -NF_ACCEPT;
 158         }
 159
 160         ctinfo = IP_CT_RELATED;
 161
 162         h = nf_conntrack_find_get(net, nf_ct_zone_tmpl(tmpl, skb, &tmp),
 163                                   &intuple);
 164         if (!h) {
 165                 pr_debug("icmpv6_error: no match\n");
 166                 return -NF_ACCEPT;
 167         } else {
 168                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
 169                         ctinfo += IP_CT_IS_REPLY;
 170         }
 171
 172         /* Update skb to refer to this connection */
 173         nf_ct_set(skb, nf_ct_tuplehash_to_ctrack(h), ctinfo);
 174         return NF_ACCEPT;
 175 }
 176
 177 static void icmpv6_error_log(const struct sk_buff *skb,
 178                              const struct nf_hook_state *state,
 179                              const char *msg)
 180 {
 181         nf_l4proto_log_invalid(skb, state->net, state->pf,
 182                                IPPROTO_ICMPV6, "%s", msg);
 183 }
 184
 185 int nf_conntrack_icmpv6_error(struct nf_conn *tmpl,
 186                               struct sk_buff *skb,
 187                               unsigned int dataoff,
 188                               const struct nf_hook_state *state)
 189 {
 190         const struct icmp6hdr *icmp6h;
 191         struct icmp6hdr _ih;
 192         int type;
 193
 194         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 195         if (icmp6h == NULL) {
 196                 icmpv6_error_log(skb, state, "short packet");
 197                 return -NF_ACCEPT;
 198         }
 199
 200         if (state->hook == NF_INET_PRE_ROUTING &&
 201             state->net->ct.sysctl_checksum &&
 202             nf_ip6_checksum(skb, state->hook, dataoff, IPPROTO_ICMPV6)) {
 203                 icmpv6_error_log(skb, state, "ICMPv6 checksum failed");
 204                 return -NF_ACCEPT;
 205         }
 206
 207         type = icmp6h->icmp6_type - 130;
 208         if (type >= 0 && type < sizeof(noct_valid_new) &&
 209             noct_valid_new[type]) {
 210                 nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
 211                 return NF_ACCEPT;
 212         }
 213
 214         /* is not error message ? */
 215         if (icmp6h->icmp6_type >= 128)
 216                 return NF_ACCEPT;
 217
 218         return icmpv6_error_message(state->net, tmpl, skb, dataoff);
 219 }
 220
 221 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 222
 223 #include <linux/netfilter/nfnetlink.h>
 224 #include <linux/netfilter/nfnetlink_conntrack.h>
 225 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
 226                                   const struct nf_conntrack_tuple *t)
 227 {
 228         if (nla_put_be16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id) ||
 229             nla_put_u8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type) ||
 230             nla_put_u8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code))
 231                 goto nla_put_failure;
 232         return 0;
 233
 234 nla_put_failure:
 235         return -1;
 236 }
 237
 238 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
 239         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
 240         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
 241         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
 242 };
 243
 244 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
 245                                 struct nf_conntrack_tuple *tuple)
 246 {
 247         if (!tb[CTA_PROTO_ICMPV6_TYPE] ||
 248             !tb[CTA_PROTO_ICMPV6_CODE] ||
 249             !tb[CTA_PROTO_ICMPV6_ID])
 250                 return -EINVAL;
 251
 252         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
 253         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
 254         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
 255
 256         if (tuple->dst.u.icmp.type < 128 ||
 257             tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
 258             !invmap[tuple->dst.u.icmp.type - 128])
 259                 return -EINVAL;
 260
 261         return 0;
 262 }
 263
 264 static unsigned int icmpv6_nlattr_tuple_size(void)
 265 {
 266         static unsigned int size __read_mostly;
 267
 268         if (!size)
 269                 size = nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
 270
 271         return size;
 272 }
 273 #endif
 274
 275 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 276
 277 #include <linux/netfilter/nfnetlink.h>
 278 #include <linux/netfilter/nfnetlink_cttimeout.h>
 279
 280 static int icmpv6_timeout_nlattr_to_obj(struct nlattr *tb[],
 281                                         struct net *net, void *data)
 282 {
 283         unsigned int *timeout = data;
 284         struct nf_icmp_net *in = nf_icmpv6_pernet(net);
 285
 286         if (!timeout)
 287                 timeout = icmpv6_get_timeouts(net);
 288         if (tb[CTA_TIMEOUT_ICMPV6_TIMEOUT]) {
 289                 *timeout =
 290                     ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMPV6_TIMEOUT])) * HZ;
 291         } else {
 292                 /* Set default ICMPv6 timeout. */
 293                 *timeout = in->timeout;
 294         }
 295         return 0;
 296 }
 297
 298 static int
 299 icmpv6_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 300 {
 301         const unsigned int *timeout = data;
 302
 303         if (nla_put_be32(skb, CTA_TIMEOUT_ICMPV6_TIMEOUT, htonl(*timeout / HZ)))
 304                 goto nla_put_failure;
 305         return 0;
 306
 307 nla_put_failure:
 308         return -ENOSPC;
 309 }
 310
 311 static const struct nla_policy
 312 icmpv6_timeout_nla_policy[CTA_TIMEOUT_ICMPV6_MAX+1] = {
 313         [CTA_TIMEOUT_ICMPV6_TIMEOUT]    = { .type = NLA_U32 },
 314 };
 315 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 316
 317 #ifdef CONFIG_SYSCTL
 318 static struct ctl_table icmpv6_sysctl_table[] = {
 319         {
 320                 .procname       = "nf_conntrack_icmpv6_timeout",
 321                 .maxlen         = sizeof(unsigned int),
 322                 .mode           = 0644,
 323                 .proc_handler   = proc_dointvec_jiffies,
 324         },
 325         { }
 326 };
 327 #endif /* CONFIG_SYSCTL */
 328
 329 static int icmpv6_kmemdup_sysctl_table(struct nf_proto_net *pn,
 330                                        struct nf_icmp_net *in)
 331 {
 332 #ifdef CONFIG_SYSCTL
 333         pn->ctl_table = kmemdup(icmpv6_sysctl_table,
 334                                 sizeof(icmpv6_sysctl_table),
 335                                 GFP_KERNEL);
 336         if (!pn->ctl_table)
 337                 return -ENOMEM;
 338
 339         pn->ctl_table[0].data = &in->timeout;
 340 #endif
 341         return 0;
 342 }
 343
 344 static int icmpv6_init_net(struct net *net)
 345 {
 346         struct nf_icmp_net *in = nf_icmpv6_pernet(net);
 347         struct nf_proto_net *pn = &in->pn;
 348
 349         in->timeout = nf_ct_icmpv6_timeout;
 350
 351         return icmpv6_kmemdup_sysctl_table(pn, in);
 352 }
 353
 354 static struct nf_proto_net *icmpv6_get_net_proto(struct net *net)
 355 {
 356         return &net->ct.nf_ct_proto.icmpv6.pn;
 357 }
 358
 359 const struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 =
 360 {
 361         .l4proto                = IPPROTO_ICMPV6,
 362         .pkt_to_tuple           = icmpv6_pkt_to_tuple,
 363         .invert_tuple           = icmpv6_invert_tuple,
 364         .packet                 = icmpv6_packet,
 365 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 366         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
 367         .nlattr_tuple_size      = icmpv6_nlattr_tuple_size,
 368         .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
 369         .nla_policy             = icmpv6_nla_policy,
 370 #endif
 371 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 372         .ctnl_timeout           = {
 373                 .nlattr_to_obj  = icmpv6_timeout_nlattr_to_obj,
 374                 .obj_to_nlattr  = icmpv6_timeout_obj_to_nlattr,
 375                 .nlattr_max     = CTA_TIMEOUT_ICMP_MAX,
 376                 .obj_size       = sizeof(unsigned int),
 377                 .nla_policy     = icmpv6_timeout_nla_policy,
 378         },
 379 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 380         .init_net               = icmpv6_init_net,
 381         .get_net_proto          = icmpv6_get_net_proto,
 382 };