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 net *net,
  40                                 struct nf_conntrack_tuple *tuple)
  41 {
  42         const struct icmp6hdr *hp;
  43         struct icmp6hdr _hdr;
  44
  45         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  46         if (hp == NULL)
  47                 return false;
  48         tuple->dst.u.icmp.type = hp->icmp6_type;
  49         tuple->src.u.icmp.id = hp->icmp6_identifier;
  50         tuple->dst.u.icmp.code = hp->icmp6_code;
  51
  52         return true;
  53 }
  54
  55 /* Add 1; spaces filled with 0. */
  56 static const u_int8_t invmap[] = {
  57         [ICMPV6_ECHO_REQUEST - 128]     = ICMPV6_ECHO_REPLY + 1,
  58         [ICMPV6_ECHO_REPLY - 128]       = ICMPV6_ECHO_REQUEST + 1,
  59         [ICMPV6_NI_QUERY - 128]         = ICMPV6_NI_REPLY + 1,
  60         [ICMPV6_NI_REPLY - 128]         = ICMPV6_NI_QUERY + 1
  61 };
  62
  63 static const u_int8_t noct_valid_new[] = {
  64         [ICMPV6_MGM_QUERY - 130] = 1,
  65         [ICMPV6_MGM_REPORT - 130] = 1,
  66         [ICMPV6_MGM_REDUCTION - 130] = 1,
  67         [NDISC_ROUTER_SOLICITATION - 130] = 1,
  68         [NDISC_ROUTER_ADVERTISEMENT - 130] = 1,
  69         [NDISC_NEIGHBOUR_SOLICITATION - 130] = 1,
  70         [NDISC_NEIGHBOUR_ADVERTISEMENT - 130] = 1,
  71         [ICMPV6_MLD2_REPORT - 130] = 1
  72 };
  73
  74 static bool icmpv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  75                                 const struct nf_conntrack_tuple *orig)
  76 {
  77         int type = orig->dst.u.icmp.type - 128;
  78         if (type < 0 || type >= sizeof(invmap) || !invmap[type])
  79                 return false;
  80
  81         tuple->src.u.icmp.id   = orig->src.u.icmp.id;
  82         tuple->dst.u.icmp.type = invmap[type] - 1;
  83         tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
  84         return true;
  85 }
  86
  87 /* Print out the per-protocol part of the tuple. */
  88 static void icmpv6_print_tuple(struct seq_file *s,
  89                               const struct nf_conntrack_tuple *tuple)
  90 {
  91         seq_printf(s, "type=%u code=%u id=%u ",
  92                    tuple->dst.u.icmp.type,
  93                    tuple->dst.u.icmp.code,
  94                    ntohs(tuple->src.u.icmp.id));
  95 }
  96
  97 static unsigned int *icmpv6_get_timeouts(struct net *net)
  98 {
  99         return &icmpv6_pernet(net)->timeout;
 100 }
 101
 102 /* Returns verdict for packet, or -1 for invalid. */
 103 static int icmpv6_packet(struct nf_conn *ct,
 104                        const struct sk_buff *skb,
 105                        unsigned int dataoff,
 106                        enum ip_conntrack_info ctinfo,
 107                        u_int8_t pf,
 108                        unsigned int hooknum,
 109                        unsigned int *timeout)
 110 {
 111         /* Do not immediately delete the connection after the first
 112            successful reply to avoid excessive conntrackd traffic
 113            and also to handle correctly ICMP echo reply duplicates. */
 114         nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
 115
 116         return NF_ACCEPT;
 117 }
 118
 119 /* Called when a new connection for this protocol found. */
 120 static bool icmpv6_new(struct nf_conn *ct, const struct sk_buff *skb,
 121                        unsigned int dataoff, unsigned int *timeouts)
 122 {
 123         static const u_int8_t valid_new[] = {
 124                 [ICMPV6_ECHO_REQUEST - 128] = 1,
 125                 [ICMPV6_NI_QUERY - 128] = 1
 126         };
 127         int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;
 128
 129         if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
 130                 /* Can't create a new ICMPv6 `conn' with this. */
 131                 pr_debug("icmpv6: can't create new conn with type %u\n",
 132                          type + 128);
 133                 nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
 134                 if (LOG_INVALID(nf_ct_net(ct), IPPROTO_ICMPV6))
 135                         nf_log_packet(nf_ct_net(ct), PF_INET6, 0, skb, NULL,
 136                                       NULL, NULL,
 137                                       "nf_ct_icmpv6: invalid new with type %d ",
 138                                       type + 128);
 139                 return false;
 140         }
 141         return true;
 142 }
 143
 144 static int
 145 icmpv6_error_message(struct net *net, struct nf_conn *tmpl,
 146                      struct sk_buff *skb,
 147                      unsigned int icmp6off,
 148                      unsigned int hooknum)
 149 {
 150         struct nf_conntrack_tuple intuple, origtuple;
 151         const struct nf_conntrack_tuple_hash *h;
 152         const struct nf_conntrack_l4proto *inproto;
 153         enum ip_conntrack_info ctinfo;
 154         struct nf_conntrack_zone tmp;
 155
 156         NF_CT_ASSERT(skb->nfct == NULL);
 157
 158         /* Are they talking about one of our connections? */
 159         if (!nf_ct_get_tuplepr(skb,
 160                                skb_network_offset(skb)
 161                                 + sizeof(struct ipv6hdr)
 162                                 + sizeof(struct icmp6hdr),
 163                                PF_INET6, net, &origtuple)) {
 164                 pr_debug("icmpv6_error: Can't get tuple\n");
 165                 return -NF_ACCEPT;
 166         }
 167
 168         /* rcu_read_lock()ed by nf_hook_thresh */
 169         inproto = __nf_ct_l4proto_find(PF_INET6, origtuple.dst.protonum);
 170
 171         /* Ordinarily, we'd expect the inverted tupleproto, but it's
 172            been preserved inside the ICMP. */
 173         if (!nf_ct_invert_tuple(&intuple, &origtuple,
 174                                 &nf_conntrack_l3proto_ipv6, inproto)) {
 175                 pr_debug("icmpv6_error: Can't invert tuple\n");
 176                 return -NF_ACCEPT;
 177         }
 178
 179         ctinfo = IP_CT_RELATED;
 180
 181         h = nf_conntrack_find_get(net, nf_ct_zone_tmpl(tmpl, skb, &tmp),
 182                                   &intuple);
 183         if (!h) {
 184                 pr_debug("icmpv6_error: no match\n");
 185                 return -NF_ACCEPT;
 186         } else {
 187                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
 188                         ctinfo += IP_CT_IS_REPLY;
 189         }
 190
 191         /* Update skb to refer to this connection */
 192         skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
 193         skb->nfctinfo = ctinfo;
 194         return NF_ACCEPT;
 195 }
 196
 197 static int
 198 icmpv6_error(struct net *net, struct nf_conn *tmpl,
 199              struct sk_buff *skb, unsigned int dataoff,
 200              u8 pf, unsigned int hooknum)
 201 {
 202         const struct icmp6hdr *icmp6h;
 203         struct icmp6hdr _ih;
 204         int type;
 205
 206         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 207         if (icmp6h == NULL) {
 208                 if (LOG_INVALID(net, IPPROTO_ICMPV6))
 209                         nf_log_packet(net, PF_INET6, 0, skb, NULL, NULL, NULL,
 210                               "nf_ct_icmpv6: short packet ");
 211                 return -NF_ACCEPT;
 212         }
 213
 214         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 215             nf_ip6_checksum(skb, hooknum, dataoff, IPPROTO_ICMPV6)) {
 216                 if (LOG_INVALID(net, IPPROTO_ICMPV6))
 217                         nf_log_packet(net, PF_INET6, 0, skb, NULL, NULL, NULL,
 218                                       "nf_ct_icmpv6: ICMPv6 checksum failed ");
 219                 return -NF_ACCEPT;
 220         }
 221
 222         type = icmp6h->icmp6_type - 130;
 223         if (type >= 0 && type < sizeof(noct_valid_new) &&
 224             noct_valid_new[type]) {
 225                 skb->nfct = &nf_ct_untracked_get()->ct_general;
 226                 skb->nfctinfo = IP_CT_NEW;
 227                 nf_conntrack_get(skb->nfct);
 228                 return NF_ACCEPT;
 229         }
 230
 231         /* is not error message ? */
 232         if (icmp6h->icmp6_type >= 128)
 233                 return NF_ACCEPT;
 234
 235         return icmpv6_error_message(net, tmpl, skb, dataoff, hooknum);
 236 }
 237
 238 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 239
 240 #include <linux/netfilter/nfnetlink.h>
 241 #include <linux/netfilter/nfnetlink_conntrack.h>
 242 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
 243                                   const struct nf_conntrack_tuple *t)
 244 {
 245         if (nla_put_be16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id) ||
 246             nla_put_u8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type) ||
 247             nla_put_u8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code))
 248                 goto nla_put_failure;
 249         return 0;
 250
 251 nla_put_failure:
 252         return -1;
 253 }
 254
 255 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
 256         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
 257         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
 258         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
 259 };
 260
 261 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
 262                                 struct nf_conntrack_tuple *tuple)
 263 {
 264         if (!tb[CTA_PROTO_ICMPV6_TYPE] ||
 265             !tb[CTA_PROTO_ICMPV6_CODE] ||
 266             !tb[CTA_PROTO_ICMPV6_ID])
 267                 return -EINVAL;
 268
 269         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
 270         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
 271         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
 272
 273         if (tuple->dst.u.icmp.type < 128 ||
 274             tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
 275             !invmap[tuple->dst.u.icmp.type - 128])
 276                 return -EINVAL;
 277
 278         return 0;
 279 }
 280
 281 static int icmpv6_nlattr_tuple_size(void)
 282 {
 283         return nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
 284 }
 285 #endif
 286
 287 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 288
 289 #include <linux/netfilter/nfnetlink.h>
 290 #include <linux/netfilter/nfnetlink_cttimeout.h>
 291
 292 static int icmpv6_timeout_nlattr_to_obj(struct nlattr *tb[],
 293                                         struct net *net, void *data)
 294 {
 295         unsigned int *timeout = data;
 296         struct nf_icmp_net *in = icmpv6_pernet(net);
 297
 298         if (tb[CTA_TIMEOUT_ICMPV6_TIMEOUT]) {
 299                 *timeout =
 300                     ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMPV6_TIMEOUT])) * HZ;
 301         } else {
 302                 /* Set default ICMPv6 timeout. */
 303                 *timeout = in->timeout;
 304         }
 305         return 0;
 306 }
 307
 308 static int
 309 icmpv6_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 310 {
 311         const unsigned int *timeout = data;
 312
 313         if (nla_put_be32(skb, CTA_TIMEOUT_ICMPV6_TIMEOUT, htonl(*timeout / HZ)))
 314                 goto nla_put_failure;
 315         return 0;
 316
 317 nla_put_failure:
 318         return -ENOSPC;
 319 }
 320
 321 static const struct nla_policy
 322 icmpv6_timeout_nla_policy[CTA_TIMEOUT_ICMPV6_MAX+1] = {
 323         [CTA_TIMEOUT_ICMPV6_TIMEOUT]    = { .type = NLA_U32 },
 324 };
 325 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 326
 327 #ifdef CONFIG_SYSCTL
 328 static struct ctl_table icmpv6_sysctl_table[] = {
 329         {
 330                 .procname       = "nf_conntrack_icmpv6_timeout",
 331                 .maxlen         = sizeof(unsigned int),
 332                 .mode           = 0644,
 333                 .proc_handler   = proc_dointvec_jiffies,
 334         },
 335         { }
 336 };
 337 #endif /* CONFIG_SYSCTL */
 338
 339 static int icmpv6_kmemdup_sysctl_table(struct nf_proto_net *pn,
 340                                        struct nf_icmp_net *in)
 341 {
 342 #ifdef CONFIG_SYSCTL
 343         pn->ctl_table = kmemdup(icmpv6_sysctl_table,
 344                                 sizeof(icmpv6_sysctl_table),
 345                                 GFP_KERNEL);
 346         if (!pn->ctl_table)
 347                 return -ENOMEM;
 348
 349         pn->ctl_table[0].data = &in->timeout;
 350 #endif
 351         return 0;
 352 }
 353
 354 static int icmpv6_init_net(struct net *net, u_int16_t proto)
 355 {
 356         struct nf_icmp_net *in = icmpv6_pernet(net);
 357         struct nf_proto_net *pn = &in->pn;
 358
 359         in->timeout = nf_ct_icmpv6_timeout;
 360
 361         return icmpv6_kmemdup_sysctl_table(pn, in);
 362 }
 363
 364 static struct nf_proto_net *icmpv6_get_net_proto(struct net *net)
 365 {
 366         return &net->ct.nf_ct_proto.icmpv6.pn;
 367 }
 368
 369 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 __read_mostly =
 370 {
 371         .l3proto                = PF_INET6,
 372         .l4proto                = IPPROTO_ICMPV6,
 373         .name                   = "icmpv6",
 374         .pkt_to_tuple           = icmpv6_pkt_to_tuple,
 375         .invert_tuple           = icmpv6_invert_tuple,
 376         .print_tuple            = icmpv6_print_tuple,
 377         .packet                 = icmpv6_packet,
 378         .get_timeouts           = icmpv6_get_timeouts,
 379         .new                    = icmpv6_new,
 380         .error                  = icmpv6_error,
 381 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 382         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
 383         .nlattr_tuple_size      = icmpv6_nlattr_tuple_size,
 384         .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
 385         .nla_policy             = icmpv6_nla_policy,
 386 #endif
 387 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 388         .ctnl_timeout           = {
 389                 .nlattr_to_obj  = icmpv6_timeout_nlattr_to_obj,
 390                 .obj_to_nlattr  = icmpv6_timeout_obj_to_nlattr,
 391                 .nlattr_max     = CTA_TIMEOUT_ICMP_MAX,
 392                 .obj_size       = sizeof(unsigned int),
 393                 .nla_policy     = icmpv6_timeout_nla_policy,
 394         },
 395 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 396         .init_net               = icmpv6_init_net,
 397         .get_net_proto          = icmpv6_get_net_proto,
 398 };