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 static unsigned int *icmpv6_get_timeouts(struct net *net)
  88 {
  89         return &icmpv6_pernet(net)->timeout;
  90 }
  91
  92 /* Returns verdict for packet, or -1 for invalid. */
  93 static int icmpv6_packet(struct nf_conn *ct,
  94                        const struct sk_buff *skb,
  95                        unsigned int dataoff,
  96                        enum ip_conntrack_info ctinfo,
  97                        unsigned int *timeout)
  98 {
  99         /* Do not immediately delete the connection after the first
 100            successful reply to avoid excessive conntrackd traffic
 101            and also to handle correctly ICMP echo reply duplicates. */
 102         nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
 103
 104         return NF_ACCEPT;
 105 }
 106
 107 /* Called when a new connection for this protocol found. */
 108 static bool icmpv6_new(struct nf_conn *ct, const struct sk_buff *skb,
 109                        unsigned int dataoff, unsigned int *timeouts)
 110 {
 111         static const u_int8_t valid_new[] = {
 112                 [ICMPV6_ECHO_REQUEST - 128] = 1,
 113                 [ICMPV6_NI_QUERY - 128] = 1
 114         };
 115         int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;
 116
 117         if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
 118                 /* Can't create a new ICMPv6 `conn' with this. */
 119                 pr_debug("icmpv6: can't create new conn with type %u\n",
 120                          type + 128);
 121                 nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
 122                 return false;
 123         }
 124         return true;
 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(PF_INET6, 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,
 156                                 &nf_conntrack_l3proto_ipv6, inproto)) {
 157                 pr_debug("icmpv6_error: Can't invert tuple\n");
 158                 return -NF_ACCEPT;
 159         }
 160
 161         ctinfo = IP_CT_RELATED;
 162
 163         h = nf_conntrack_find_get(net, nf_ct_zone_tmpl(tmpl, skb, &tmp),
 164                                   &intuple);
 165         if (!h) {
 166                 pr_debug("icmpv6_error: no match\n");
 167                 return -NF_ACCEPT;
 168         } else {
 169                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
 170                         ctinfo += IP_CT_IS_REPLY;
 171         }
 172
 173         /* Update skb to refer to this connection */
 174         nf_ct_set(skb, nf_ct_tuplehash_to_ctrack(h), ctinfo);
 175         return NF_ACCEPT;
 176 }
 177
 178 static void icmpv6_error_log(const struct sk_buff *skb, struct net *net,
 179                              u8 pf, const char *msg)
 180 {
 181         nf_l4proto_log_invalid(skb, net, pf, IPPROTO_ICMPV6, "%s", msg);
 182 }
 183
 184 static int
 185 icmpv6_error(struct net *net, struct nf_conn *tmpl,
 186              struct sk_buff *skb, unsigned int dataoff,
 187              u8 pf, unsigned int hooknum)
 188 {
 189         const struct icmp6hdr *icmp6h;
 190         struct icmp6hdr _ih;
 191         int type;
 192
 193         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 194         if (icmp6h == NULL) {
 195                 icmpv6_error_log(skb, net, pf, "short packet");
 196                 return -NF_ACCEPT;
 197         }
 198
 199         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 200             nf_ip6_checksum(skb, hooknum, dataoff, IPPROTO_ICMPV6)) {
 201                 icmpv6_error_log(skb, net, pf, "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         /* is not error message ? */
 213         if (icmp6h->icmp6_type >= 128)
 214                 return NF_ACCEPT;
 215
 216         return icmpv6_error_message(net, tmpl, skb, dataoff);
 217 }
 218
 219 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 220
 221 #include <linux/netfilter/nfnetlink.h>
 222 #include <linux/netfilter/nfnetlink_conntrack.h>
 223 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
 224                                   const struct nf_conntrack_tuple *t)
 225 {
 226         if (nla_put_be16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id) ||
 227             nla_put_u8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type) ||
 228             nla_put_u8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code))
 229                 goto nla_put_failure;
 230         return 0;
 231
 232 nla_put_failure:
 233         return -1;
 234 }
 235
 236 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
 237         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
 238         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
 239         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
 240 };
 241
 242 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
 243                                 struct nf_conntrack_tuple *tuple)
 244 {
 245         if (!tb[CTA_PROTO_ICMPV6_TYPE] ||
 246             !tb[CTA_PROTO_ICMPV6_CODE] ||
 247             !tb[CTA_PROTO_ICMPV6_ID])
 248                 return -EINVAL;
 249
 250         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
 251         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
 252         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
 253
 254         if (tuple->dst.u.icmp.type < 128 ||
 255             tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
 256             !invmap[tuple->dst.u.icmp.type - 128])
 257                 return -EINVAL;
 258
 259         return 0;
 260 }
 261
 262 static unsigned int icmpv6_nlattr_tuple_size(void)
 263 {
 264         static unsigned int size __read_mostly;
 265
 266         if (!size)
 267                 size = nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
 268
 269         return size;
 270 }
 271 #endif
 272
 273 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 274
 275 #include <linux/netfilter/nfnetlink.h>
 276 #include <linux/netfilter/nfnetlink_cttimeout.h>
 277
 278 static int icmpv6_timeout_nlattr_to_obj(struct nlattr *tb[],
 279                                         struct net *net, void *data)
 280 {
 281         unsigned int *timeout = data;
 282         struct nf_icmp_net *in = icmpv6_pernet(net);
 283
 284         if (tb[CTA_TIMEOUT_ICMPV6_TIMEOUT]) {
 285                 *timeout =
 286                     ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMPV6_TIMEOUT])) * HZ;
 287         } else {
 288                 /* Set default ICMPv6 timeout. */
 289                 *timeout = in->timeout;
 290         }
 291         return 0;
 292 }
 293
 294 static int
 295 icmpv6_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 296 {
 297         const unsigned int *timeout = data;
 298
 299         if (nla_put_be32(skb, CTA_TIMEOUT_ICMPV6_TIMEOUT, htonl(*timeout / HZ)))
 300                 goto nla_put_failure;
 301         return 0;
 302
 303 nla_put_failure:
 304         return -ENOSPC;
 305 }
 306
 307 static const struct nla_policy
 308 icmpv6_timeout_nla_policy[CTA_TIMEOUT_ICMPV6_MAX+1] = {
 309         [CTA_TIMEOUT_ICMPV6_TIMEOUT]    = { .type = NLA_U32 },
 310 };
 311 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 312
 313 #ifdef CONFIG_SYSCTL
 314 static struct ctl_table icmpv6_sysctl_table[] = {
 315         {
 316                 .procname       = "nf_conntrack_icmpv6_timeout",
 317                 .maxlen         = sizeof(unsigned int),
 318                 .mode           = 0644,
 319                 .proc_handler   = proc_dointvec_jiffies,
 320         },
 321         { }
 322 };
 323 #endif /* CONFIG_SYSCTL */
 324
 325 static int icmpv6_kmemdup_sysctl_table(struct nf_proto_net *pn,
 326                                        struct nf_icmp_net *in)
 327 {
 328 #ifdef CONFIG_SYSCTL
 329         pn->ctl_table = kmemdup(icmpv6_sysctl_table,
 330                                 sizeof(icmpv6_sysctl_table),
 331                                 GFP_KERNEL);
 332         if (!pn->ctl_table)
 333                 return -ENOMEM;
 334
 335         pn->ctl_table[0].data = &in->timeout;
 336 #endif
 337         return 0;
 338 }
 339
 340 static int icmpv6_init_net(struct net *net, u_int16_t proto)
 341 {
 342         struct nf_icmp_net *in = icmpv6_pernet(net);
 343         struct nf_proto_net *pn = &in->pn;
 344
 345         in->timeout = nf_ct_icmpv6_timeout;
 346
 347         return icmpv6_kmemdup_sysctl_table(pn, in);
 348 }
 349
 350 static struct nf_proto_net *icmpv6_get_net_proto(struct net *net)
 351 {
 352         return &net->ct.nf_ct_proto.icmpv6.pn;
 353 }
 354
 355 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 __read_mostly =
 356 {
 357         .l3proto                = PF_INET6,
 358         .l4proto                = IPPROTO_ICMPV6,
 359         .pkt_to_tuple           = icmpv6_pkt_to_tuple,
 360         .invert_tuple           = icmpv6_invert_tuple,
 361         .packet                 = icmpv6_packet,
 362         .get_timeouts           = icmpv6_get_timeouts,
 363         .new                    = icmpv6_new,
 364         .error                  = icmpv6_error,
 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 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_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_CT_NETLINK_TIMEOUT */
 380         .init_net               = icmpv6_init_net,
 381         .get_net_proto          = icmpv6_get_net_proto,
 382 };