net/ipv6/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_zones.h>
  27 #include <net/netfilter/ipv6/nf_conntrack_icmpv6.h>
  28 #include <net/netfilter/nf_log.h>
  29
  30 static unsigned int nf_ct_icmpv6_timeout __read_mostly = 30*HZ;
  31
  32 static bool icmpv6_pkt_to_tuple(const struct sk_buff *skb,
  33                                 unsigned int dataoff,
  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 static bool icmpv6_invert_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 /* Print out the per-protocol part of the tuple. */
  82 static int icmpv6_print_tuple(struct seq_file *s,
  83                               const struct nf_conntrack_tuple *tuple)
  84 {
  85         return seq_printf(s, "type=%u code=%u id=%u ",
  86                           tuple->dst.u.icmp.type,
  87                           tuple->dst.u.icmp.code,
  88                           ntohs(tuple->src.u.icmp.id));
  89 }
  90
  91 static unsigned int *icmpv6_get_timeouts(struct net *net)
  92 {
  93         return &nf_ct_icmpv6_timeout;
  94 }
  95
  96 /* Returns verdict for packet, or -1 for invalid. */
  97 static int icmpv6_packet(struct nf_conn *ct,
  98                        const struct sk_buff *skb,
  99                        unsigned int dataoff,
 100                        enum ip_conntrack_info ctinfo,
 101                        u_int8_t pf,
 102                        unsigned int hooknum,
 103                        unsigned int *timeout)
 104 {
 105         /* Do not immediately delete the connection after the first
 106            successful reply to avoid excessive conntrackd traffic
 107            and also to handle correctly ICMP echo reply duplicates. */
 108         nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
 109
 110         return NF_ACCEPT;
 111 }
 112
 113 /* Called when a new connection for this protocol found. */
 114 static bool icmpv6_new(struct nf_conn *ct, const struct sk_buff *skb,
 115                        unsigned int dataoff, unsigned int *timeouts)
 116 {
 117         static const u_int8_t valid_new[] = {
 118                 [ICMPV6_ECHO_REQUEST - 128] = 1,
 119                 [ICMPV6_NI_QUERY - 128] = 1
 120         };
 121         int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;
 122
 123         if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
 124                 /* Can't create a new ICMPv6 `conn' with this. */
 125                 pr_debug("icmpv6: can't create new conn with type %u\n",
 126                          type + 128);
 127                 nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
 128                 if (LOG_INVALID(nf_ct_net(ct), IPPROTO_ICMPV6))
 129                         nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 130                                       "nf_ct_icmpv6: invalid new with type %d ",
 131                                       type + 128);
 132                 return false;
 133         }
 134         return true;
 135 }
 136
 137 static int
 138 icmpv6_error_message(struct net *net, struct nf_conn *tmpl,
 139                      struct sk_buff *skb,
 140                      unsigned int icmp6off,
 141                      enum ip_conntrack_info *ctinfo,
 142                      unsigned int hooknum)
 143 {
 144         struct nf_conntrack_tuple intuple, origtuple;
 145         const struct nf_conntrack_tuple_hash *h;
 146         const struct nf_conntrack_l4proto *inproto;
 147         u16 zone = tmpl ? nf_ct_zone(tmpl) : NF_CT_DEFAULT_ZONE;
 148
 149         NF_CT_ASSERT(skb->nfct == NULL);
 150
 151         /* Are they talking about one of our connections? */
 152         if (!nf_ct_get_tuplepr(skb,
 153                                skb_network_offset(skb)
 154                                 + sizeof(struct ipv6hdr)
 155                                 + sizeof(struct icmp6hdr),
 156                                PF_INET6, &origtuple)) {
 157                 pr_debug("icmpv6_error: Can't get tuple\n");
 158                 return -NF_ACCEPT;
 159         }
 160
 161         /* rcu_read_lock()ed by nf_hook_slow */
 162         inproto = __nf_ct_l4proto_find(PF_INET6, origtuple.dst.protonum);
 163
 164         /* Ordinarily, we'd expect the inverted tupleproto, but it's
 165            been preserved inside the ICMP. */
 166         if (!nf_ct_invert_tuple(&intuple, &origtuple,
 167                                 &nf_conntrack_l3proto_ipv6, inproto)) {
 168                 pr_debug("icmpv6_error: Can't invert tuple\n");
 169                 return -NF_ACCEPT;
 170         }
 171
 172         *ctinfo = IP_CT_RELATED;
 173
 174         h = nf_conntrack_find_get(net, zone, &intuple);
 175         if (!h) {
 176                 pr_debug("icmpv6_error: no match\n");
 177                 return -NF_ACCEPT;
 178         } else {
 179                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
 180                         *ctinfo += IP_CT_IS_REPLY;
 181         }
 182
 183         /* Update skb to refer to this connection */
 184         skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
 185         skb->nfctinfo = *ctinfo;
 186         return NF_ACCEPT;
 187 }
 188
 189 static int
 190 icmpv6_error(struct net *net, struct nf_conn *tmpl,
 191              struct sk_buff *skb, unsigned int dataoff,
 192              enum ip_conntrack_info *ctinfo, u_int8_t pf, unsigned int hooknum)
 193 {
 194         const struct icmp6hdr *icmp6h;
 195         struct icmp6hdr _ih;
 196         int type;
 197
 198         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 199         if (icmp6h == NULL) {
 200                 if (LOG_INVALID(net, IPPROTO_ICMPV6))
 201                 nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 202                               "nf_ct_icmpv6: short packet ");
 203                 return -NF_ACCEPT;
 204         }
 205
 206         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 207             nf_ip6_checksum(skb, hooknum, dataoff, IPPROTO_ICMPV6)) {
 208                 if (LOG_INVALID(net, IPPROTO_ICMPV6))
 209                         nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 210                                       "nf_ct_icmpv6: ICMPv6 checksum failed ");
 211                 return -NF_ACCEPT;
 212         }
 213
 214         type = icmp6h->icmp6_type - 130;
 215         if (type >= 0 && type < sizeof(noct_valid_new) &&
 216             noct_valid_new[type]) {
 217                 skb->nfct = &nf_ct_untracked_get()->ct_general;
 218                 skb->nfctinfo = IP_CT_NEW;
 219                 nf_conntrack_get(skb->nfct);
 220                 return NF_ACCEPT;
 221         }
 222
 223         /* is not error message ? */
 224         if (icmp6h->icmp6_type >= 128)
 225                 return NF_ACCEPT;
 226
 227         return icmpv6_error_message(net, tmpl, skb, dataoff, ctinfo, hooknum);
 228 }
 229
 230 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 231
 232 #include <linux/netfilter/nfnetlink.h>
 233 #include <linux/netfilter/nfnetlink_conntrack.h>
 234 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
 235                                   const struct nf_conntrack_tuple *t)
 236 {
 237         if (nla_put_be16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id) ||
 238             nla_put_u8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type) ||
 239             nla_put_u8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code))
 240                 goto nla_put_failure;
 241         return 0;
 242
 243 nla_put_failure:
 244         return -1;
 245 }
 246
 247 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
 248         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
 249         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
 250         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
 251 };
 252
 253 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
 254                                 struct nf_conntrack_tuple *tuple)
 255 {
 256         if (!tb[CTA_PROTO_ICMPV6_TYPE] ||
 257             !tb[CTA_PROTO_ICMPV6_CODE] ||
 258             !tb[CTA_PROTO_ICMPV6_ID])
 259                 return -EINVAL;
 260
 261         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
 262         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
 263         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
 264
 265         if (tuple->dst.u.icmp.type < 128 ||
 266             tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
 267             !invmap[tuple->dst.u.icmp.type - 128])
 268                 return -EINVAL;
 269
 270         return 0;
 271 }
 272
 273 static int icmpv6_nlattr_tuple_size(void)
 274 {
 275         return nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
 276 }
 277 #endif
 278
 279 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 280
 281 #include <linux/netfilter/nfnetlink.h>
 282 #include <linux/netfilter/nfnetlink_cttimeout.h>
 283
 284 static int icmpv6_timeout_nlattr_to_obj(struct nlattr *tb[], void *data)
 285 {
 286         unsigned int *timeout = data;
 287
 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 = nf_ct_icmpv6_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_CT_NETLINK_TIMEOUT */
 316
 317 #ifdef CONFIG_SYSCTL
 318 static struct ctl_table_header *icmpv6_sysctl_header;
 319 static struct ctl_table icmpv6_sysctl_table[] = {
 320         {
 321                 .procname       = "nf_conntrack_icmpv6_timeout",
 322                 .data           = &nf_ct_icmpv6_timeout,
 323                 .maxlen         = sizeof(unsigned int),
 324                 .mode           = 0644,
 325                 .proc_handler   = proc_dointvec_jiffies,
 326         },
 327         { }
 328 };
 329 #endif /* CONFIG_SYSCTL */
 330
 331 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 __read_mostly =
 332 {
 333         .l3proto                = PF_INET6,
 334         .l4proto                = IPPROTO_ICMPV6,
 335         .name                   = "icmpv6",
 336         .pkt_to_tuple           = icmpv6_pkt_to_tuple,
 337         .invert_tuple           = icmpv6_invert_tuple,
 338         .print_tuple            = icmpv6_print_tuple,
 339         .packet                 = icmpv6_packet,
 340         .get_timeouts           = icmpv6_get_timeouts,
 341         .new                    = icmpv6_new,
 342         .error                  = icmpv6_error,
 343 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 344         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
 345         .nlattr_tuple_size      = icmpv6_nlattr_tuple_size,
 346         .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
 347         .nla_policy             = icmpv6_nla_policy,
 348 #endif
 349 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 350         .ctnl_timeout           = {
 351                 .nlattr_to_obj  = icmpv6_timeout_nlattr_to_obj,
 352                 .obj_to_nlattr  = icmpv6_timeout_obj_to_nlattr,
 353                 .nlattr_max     = CTA_TIMEOUT_ICMP_MAX,
 354                 .obj_size       = sizeof(unsigned int),
 355                 .nla_policy     = icmpv6_timeout_nla_policy,
 356         },
 357 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 358 #ifdef CONFIG_SYSCTL
 359         .ctl_table_header       = &icmpv6_sysctl_header,
 360         .ctl_table              = icmpv6_sysctl_table,
 361 #endif
 362 };