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 inline struct nf_icmp_net *icmpv6_pernet(struct net *net)
  33 {
  34         return &net->ct.nf_ct_proto.icmpv6;
  35 }
  36
  37 static bool icmpv6_pkt_to_tuple(const struct sk_buff *skb,
  38                                 unsigned int dataoff,
  39                                 struct nf_conntrack_tuple *tuple)
  40 {
  41         const struct icmp6hdr *hp;
  42         struct icmp6hdr _hdr;
  43
  44         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  45         if (hp == NULL)
  46                 return false;
  47         tuple->dst.u.icmp.type = hp->icmp6_type;
  48         tuple->src.u.icmp.id = hp->icmp6_identifier;
  49         tuple->dst.u.icmp.code = hp->icmp6_code;
  50
  51         return true;
  52 }
  53
  54 /* Add 1; spaces filled with 0. */
  55 static const u_int8_t invmap[] = {
  56         [ICMPV6_ECHO_REQUEST - 128]     = ICMPV6_ECHO_REPLY + 1,
  57         [ICMPV6_ECHO_REPLY - 128]       = ICMPV6_ECHO_REQUEST + 1,
  58         [ICMPV6_NI_QUERY - 128]         = ICMPV6_NI_REPLY + 1,
  59         [ICMPV6_NI_REPLY - 128]         = ICMPV6_NI_QUERY +1
  60 };
  61
  62 static const u_int8_t noct_valid_new[] = {
  63         [ICMPV6_MGM_QUERY - 130] = 1,
  64         [ICMPV6_MGM_REPORT -130] = 1,
  65         [ICMPV6_MGM_REDUCTION - 130] = 1,
  66         [NDISC_ROUTER_SOLICITATION - 130] = 1,
  67         [NDISC_ROUTER_ADVERTISEMENT - 130] = 1,
  68         [NDISC_NEIGHBOUR_SOLICITATION - 130] = 1,
  69         [NDISC_NEIGHBOUR_ADVERTISEMENT - 130] = 1,
  70         [ICMPV6_MLD2_REPORT - 130] = 1
  71 };
  72
  73 static bool icmpv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  74                                 const struct nf_conntrack_tuple *orig)
  75 {
  76         int type = orig->dst.u.icmp.type - 128;
  77         if (type < 0 || type >= sizeof(invmap) || !invmap[type])
  78                 return false;
  79
  80         tuple->src.u.icmp.id   = orig->src.u.icmp.id;
  81         tuple->dst.u.icmp.type = invmap[type] - 1;
  82         tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
  83         return true;
  84 }
  85
  86 /* Print out the per-protocol part of the tuple. */
  87 static int icmpv6_print_tuple(struct seq_file *s,
  88                               const struct nf_conntrack_tuple *tuple)
  89 {
  90         return seq_printf(s, "type=%u code=%u id=%u ",
  91                           tuple->dst.u.icmp.type,
  92                           tuple->dst.u.icmp.code,
  93                           ntohs(tuple->src.u.icmp.id));
  94 }
  95
  96 static unsigned int *icmpv6_get_timeouts(struct net *net)
  97 {
  98         return &icmpv6_pernet(net)->timeout;
  99 }
 100
 101 /* Returns verdict for packet, or -1 for invalid. */
 102 static int icmpv6_packet(struct nf_conn *ct,
 103                        const struct sk_buff *skb,
 104                        unsigned int dataoff,
 105                        enum ip_conntrack_info ctinfo,
 106                        u_int8_t pf,
 107                        unsigned int hooknum,
 108                        unsigned int *timeout)
 109 {
 110         /* Do not immediately delete the connection after the first
 111            successful reply to avoid excessive conntrackd traffic
 112            and also to handle correctly ICMP echo reply duplicates. */
 113         nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
 114
 115         return NF_ACCEPT;
 116 }
 117
 118 /* Called when a new connection for this protocol found. */
 119 static bool icmpv6_new(struct nf_conn *ct, const struct sk_buff *skb,
 120                        unsigned int dataoff, unsigned int *timeouts)
 121 {
 122         static const u_int8_t valid_new[] = {
 123                 [ICMPV6_ECHO_REQUEST - 128] = 1,
 124                 [ICMPV6_NI_QUERY - 128] = 1
 125         };
 126         int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;
 127
 128         if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
 129                 /* Can't create a new ICMPv6 `conn' with this. */
 130                 pr_debug("icmpv6: can't create new conn with type %u\n",
 131                          type + 128);
 132                 nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
 133                 if (LOG_INVALID(nf_ct_net(ct), IPPROTO_ICMPV6))
 134                         nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 135                                       "nf_ct_icmpv6: invalid new with type %d ",
 136                                       type + 128);
 137                 return false;
 138         }
 139         return true;
 140 }
 141
 142 static int
 143 icmpv6_error_message(struct net *net, struct nf_conn *tmpl,
 144                      struct sk_buff *skb,
 145                      unsigned int icmp6off,
 146                      enum ip_conntrack_info *ctinfo,
 147                      unsigned int hooknum)
 148 {
 149         struct nf_conntrack_tuple intuple, origtuple;
 150         const struct nf_conntrack_tuple_hash *h;
 151         const struct nf_conntrack_l4proto *inproto;
 152         u16 zone = tmpl ? nf_ct_zone(tmpl) : NF_CT_DEFAULT_ZONE;
 153
 154         NF_CT_ASSERT(skb->nfct == NULL);
 155
 156         /* Are they talking about one of our connections? */
 157         if (!nf_ct_get_tuplepr(skb,
 158                                skb_network_offset(skb)
 159                                 + sizeof(struct ipv6hdr)
 160                                 + sizeof(struct icmp6hdr),
 161                                PF_INET6, &origtuple)) {
 162                 pr_debug("icmpv6_error: Can't get tuple\n");
 163                 return -NF_ACCEPT;
 164         }
 165
 166         /* rcu_read_lock()ed by nf_hook_slow */
 167         inproto = __nf_ct_l4proto_find(PF_INET6, origtuple.dst.protonum);
 168
 169         /* Ordinarily, we'd expect the inverted tupleproto, but it's
 170            been preserved inside the ICMP. */
 171         if (!nf_ct_invert_tuple(&intuple, &origtuple,
 172                                 &nf_conntrack_l3proto_ipv6, inproto)) {
 173                 pr_debug("icmpv6_error: Can't invert tuple\n");
 174                 return -NF_ACCEPT;
 175         }
 176
 177         *ctinfo = IP_CT_RELATED;
 178
 179         h = nf_conntrack_find_get(net, zone, &intuple);
 180         if (!h) {
 181                 pr_debug("icmpv6_error: no match\n");
 182                 return -NF_ACCEPT;
 183         } else {
 184                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
 185                         *ctinfo += IP_CT_IS_REPLY;
 186         }
 187
 188         /* Update skb to refer to this connection */
 189         skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
 190         skb->nfctinfo = *ctinfo;
 191         return NF_ACCEPT;
 192 }
 193
 194 static int
 195 icmpv6_error(struct net *net, struct nf_conn *tmpl,
 196              struct sk_buff *skb, unsigned int dataoff,
 197              enum ip_conntrack_info *ctinfo, u_int8_t pf, unsigned int hooknum)
 198 {
 199         const struct icmp6hdr *icmp6h;
 200         struct icmp6hdr _ih;
 201         int type;
 202
 203         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 204         if (icmp6h == NULL) {
 205                 if (LOG_INVALID(net, IPPROTO_ICMPV6))
 206                 nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 207                               "nf_ct_icmpv6: short packet ");
 208                 return -NF_ACCEPT;
 209         }
 210
 211         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 212             nf_ip6_checksum(skb, hooknum, dataoff, IPPROTO_ICMPV6)) {
 213                 if (LOG_INVALID(net, IPPROTO_ICMPV6))
 214                         nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 215                                       "nf_ct_icmpv6: ICMPv6 checksum failed ");
 216                 return -NF_ACCEPT;
 217         }
 218
 219         type = icmp6h->icmp6_type - 130;
 220         if (type >= 0 && type < sizeof(noct_valid_new) &&
 221             noct_valid_new[type]) {
 222                 skb->nfct = &nf_ct_untracked_get()->ct_general;
 223                 skb->nfctinfo = IP_CT_NEW;
 224                 nf_conntrack_get(skb->nfct);
 225                 return NF_ACCEPT;
 226         }
 227
 228         /* is not error message ? */
 229         if (icmp6h->icmp6_type >= 128)
 230                 return NF_ACCEPT;
 231
 232         return icmpv6_error_message(net, tmpl, skb, dataoff, ctinfo, hooknum);
 233 }
 234
 235 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 236
 237 #include <linux/netfilter/nfnetlink.h>
 238 #include <linux/netfilter/nfnetlink_conntrack.h>
 239 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
 240                                   const struct nf_conntrack_tuple *t)
 241 {
 242         if (nla_put_be16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id) ||
 243             nla_put_u8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type) ||
 244             nla_put_u8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code))
 245                 goto nla_put_failure;
 246         return 0;
 247
 248 nla_put_failure:
 249         return -1;
 250 }
 251
 252 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
 253         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
 254         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
 255         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
 256 };
 257
 258 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
 259                                 struct nf_conntrack_tuple *tuple)
 260 {
 261         if (!tb[CTA_PROTO_ICMPV6_TYPE] ||
 262             !tb[CTA_PROTO_ICMPV6_CODE] ||
 263             !tb[CTA_PROTO_ICMPV6_ID])
 264                 return -EINVAL;
 265
 266         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
 267         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
 268         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
 269
 270         if (tuple->dst.u.icmp.type < 128 ||
 271             tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
 272             !invmap[tuple->dst.u.icmp.type - 128])
 273                 return -EINVAL;
 274
 275         return 0;
 276 }
 277
 278 static int icmpv6_nlattr_tuple_size(void)
 279 {
 280         return nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
 281 }
 282 #endif
 283
 284 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 285
 286 #include <linux/netfilter/nfnetlink.h>
 287 #include <linux/netfilter/nfnetlink_cttimeout.h>
 288
 289 static int icmpv6_timeout_nlattr_to_obj(struct nlattr *tb[],
 290                                         struct net *net, void *data)
 291 {
 292         unsigned int *timeout = data;
 293         struct nf_icmp_net *in = icmpv6_pernet(net);
 294
 295         if (tb[CTA_TIMEOUT_ICMPV6_TIMEOUT]) {
 296                 *timeout =
 297                     ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMPV6_TIMEOUT])) * HZ;
 298         } else {
 299                 /* Set default ICMPv6 timeout. */
 300                 *timeout = in->timeout;
 301         }
 302         return 0;
 303 }
 304
 305 static int
 306 icmpv6_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 307 {
 308         const unsigned int *timeout = data;
 309
 310         if (nla_put_be32(skb, CTA_TIMEOUT_ICMPV6_TIMEOUT, htonl(*timeout / HZ)))
 311                 goto nla_put_failure;
 312         return 0;
 313
 314 nla_put_failure:
 315         return -ENOSPC;
 316 }
 317
 318 static const struct nla_policy
 319 icmpv6_timeout_nla_policy[CTA_TIMEOUT_ICMPV6_MAX+1] = {
 320         [CTA_TIMEOUT_ICMPV6_TIMEOUT]    = { .type = NLA_U32 },
 321 };
 322 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 323
 324 #ifdef CONFIG_SYSCTL
 325 static struct ctl_table icmpv6_sysctl_table[] = {
 326         {
 327                 .procname       = "nf_conntrack_icmpv6_timeout",
 328                 .maxlen         = sizeof(unsigned int),
 329                 .mode           = 0644,
 330                 .proc_handler   = proc_dointvec_jiffies,
 331         },
 332         { }
 333 };
 334 #endif /* CONFIG_SYSCTL */
 335
 336 static int icmpv6_kmemdup_sysctl_table(struct nf_proto_net *pn,
 337                                        struct nf_icmp_net *in)
 338 {
 339 #ifdef CONFIG_SYSCTL
 340         pn->ctl_table = kmemdup(icmpv6_sysctl_table,
 341                                 sizeof(icmpv6_sysctl_table),
 342                                 GFP_KERNEL);
 343         if (!pn->ctl_table)
 344                 return -ENOMEM;
 345
 346         pn->ctl_table[0].data = &in->timeout;
 347 #endif
 348         return 0;
 349 }
 350
 351 static int icmpv6_init_net(struct net *net, u_int16_t proto)
 352 {
 353         struct nf_icmp_net *in = icmpv6_pernet(net);
 354         struct nf_proto_net *pn = &in->pn;
 355
 356         in->timeout = nf_ct_icmpv6_timeout;
 357
 358         return icmpv6_kmemdup_sysctl_table(pn, in);
 359 }
 360
 361 static struct nf_proto_net *icmpv6_get_net_proto(struct net *net)
 362 {
 363         return &net->ct.nf_ct_proto.icmpv6.pn;
 364 }
 365
 366 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 __read_mostly =
 367 {
 368         .l3proto                = PF_INET6,
 369         .l4proto                = IPPROTO_ICMPV6,
 370         .name                   = "icmpv6",
 371         .pkt_to_tuple           = icmpv6_pkt_to_tuple,
 372         .invert_tuple           = icmpv6_invert_tuple,
 373         .print_tuple            = icmpv6_print_tuple,
 374         .packet                 = icmpv6_packet,
 375         .get_timeouts           = icmpv6_get_timeouts,
 376         .new                    = icmpv6_new,
 377         .error                  = icmpv6_error,
 378 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 379         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
 380         .nlattr_tuple_size      = icmpv6_nlattr_tuple_size,
 381         .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
 382         .nla_policy             = icmpv6_nla_policy,
 383 #endif
 384 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 385         .ctnl_timeout           = {
 386                 .nlattr_to_obj  = icmpv6_timeout_nlattr_to_obj,
 387                 .obj_to_nlattr  = icmpv6_timeout_obj_to_nlattr,
 388                 .nlattr_max     = CTA_TIMEOUT_ICMP_MAX,
 389                 .obj_size       = sizeof(unsigned int),
 390                 .nla_policy     = icmpv6_timeout_nla_policy,
 391         },
 392 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 393         .init_net               = icmpv6_init_net,
 394         .get_net_proto          = icmpv6_get_net_proto,
 395 };