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