net/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_timeout.h>
  27 #include <net/netfilter/nf_conntrack_zones.h>
  28 #include <net/netfilter/ipv6/nf_conntrack_icmpv6.h>
  29 #include <net/netfilter/nf_log.h>
  30
  31 static const unsigned int nf_ct_icmpv6_timeout = 30*HZ;
  32
  33 static inline struct nf_icmp_net *icmpv6_pernet(struct net *net)
  34 {
  35         return &net->ct.nf_ct_proto.icmpv6;
  36 }
  37
  38 static bool icmpv6_pkt_to_tuple(const struct sk_buff *skb,
  39                                 unsigned int dataoff,
  40                                 struct net *net,
  41                                 struct nf_conntrack_tuple *tuple)
  42 {
  43         const struct icmp6hdr *hp;
  44         struct icmp6hdr _hdr;
  45
  46         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  47         if (hp == NULL)
  48                 return false;
  49         tuple->dst.u.icmp.type = hp->icmp6_type;
  50         tuple->src.u.icmp.id = hp->icmp6_identifier;
  51         tuple->dst.u.icmp.code = hp->icmp6_code;
  52
  53         return true;
  54 }
  55
  56 /* Add 1; spaces filled with 0. */
  57 static const u_int8_t invmap[] = {
  58         [ICMPV6_ECHO_REQUEST - 128]     = ICMPV6_ECHO_REPLY + 1,
  59         [ICMPV6_ECHO_REPLY - 128]       = ICMPV6_ECHO_REQUEST + 1,
  60         [ICMPV6_NI_QUERY - 128]         = ICMPV6_NI_REPLY + 1,
  61         [ICMPV6_NI_REPLY - 128]         = ICMPV6_NI_QUERY + 1
  62 };
  63
  64 static const u_int8_t noct_valid_new[] = {
  65         [ICMPV6_MGM_QUERY - 130] = 1,
  66         [ICMPV6_MGM_REPORT - 130] = 1,
  67         [ICMPV6_MGM_REDUCTION - 130] = 1,
  68         [NDISC_ROUTER_SOLICITATION - 130] = 1,
  69         [NDISC_ROUTER_ADVERTISEMENT - 130] = 1,
  70         [NDISC_NEIGHBOUR_SOLICITATION - 130] = 1,
  71         [NDISC_NEIGHBOUR_ADVERTISEMENT - 130] = 1,
  72         [ICMPV6_MLD2_REPORT - 130] = 1
  73 };
  74
  75 static bool icmpv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  76                                 const struct nf_conntrack_tuple *orig)
  77 {
  78         int type = orig->dst.u.icmp.type - 128;
  79         if (type < 0 || type >= sizeof(invmap) || !invmap[type])
  80                 return false;
  81
  82         tuple->src.u.icmp.id   = orig->src.u.icmp.id;
  83         tuple->dst.u.icmp.type = invmap[type] - 1;
  84         tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
  85         return true;
  86 }
  87
  88 static unsigned int *icmpv6_get_timeouts(struct net *net)
  89 {
  90         return &icmpv6_pernet(net)->timeout;
  91 }
  92
  93 /* Returns verdict for packet, or -1 for invalid. */
  94 static int icmpv6_packet(struct nf_conn *ct,
  95                          struct sk_buff *skb,
  96                          unsigned int dataoff,
  97                          enum ip_conntrack_info ctinfo,
  98                          const struct nf_hook_state *state)
  99 {
 100         unsigned int *timeout = nf_ct_timeout_lookup(ct);
 101         static const u8 valid_new[] = {
 102                 [ICMPV6_ECHO_REQUEST - 128] = 1,
 103                 [ICMPV6_NI_QUERY - 128] = 1
 104         };
 105
 106         if (state->pf != NFPROTO_IPV6)
 107                 return -NF_ACCEPT;
 108
 109         if (!nf_ct_is_confirmed(ct)) {
 110                 int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;
 111
 112                 if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
 113                         /* Can't create a new ICMPv6 `conn' with this. */
 114                         pr_debug("icmpv6: can't create new conn with type %u\n",
 115                                  type + 128);
 116                         nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
 117                         return -NF_ACCEPT;
 118                 }
 119         }
 120
 121         if (!timeout)
 122                 timeout = icmpv6_get_timeouts(nf_ct_net(ct));
 123
 124         /* Do not immediately delete the connection after the first
 125            successful reply to avoid excessive conntrackd traffic
 126            and also to handle correctly ICMP echo reply duplicates. */
 127         nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
 128
 129         return NF_ACCEPT;
 130 }
 131
 132 static int
 133 icmpv6_error_message(struct net *net, struct nf_conn *tmpl,
 134                      struct sk_buff *skb,
 135                      unsigned int icmp6off)
 136 {
 137         struct nf_conntrack_tuple intuple, origtuple;
 138         const struct nf_conntrack_tuple_hash *h;
 139         const struct nf_conntrack_l4proto *inproto;
 140         enum ip_conntrack_info ctinfo;
 141         struct nf_conntrack_zone tmp;
 142
 143         WARN_ON(skb_nfct(skb));
 144
 145         /* Are they talking about one of our connections? */
 146         if (!nf_ct_get_tuplepr(skb,
 147                                skb_network_offset(skb)
 148                                 + sizeof(struct ipv6hdr)
 149                                 + sizeof(struct icmp6hdr),
 150                                PF_INET6, net, &origtuple)) {
 151                 pr_debug("icmpv6_error: Can't get tuple\n");
 152                 return -NF_ACCEPT;
 153         }
 154
 155         /* rcu_read_lock()ed by nf_hook_thresh */
 156         inproto = __nf_ct_l4proto_find(origtuple.dst.protonum);
 157
 158         /* Ordinarily, we'd expect the inverted tupleproto, but it's
 159            been preserved inside the ICMP. */
 160         if (!nf_ct_invert_tuple(&intuple, &origtuple, inproto)) {
 161                 pr_debug("icmpv6_error: Can't invert tuple\n");
 162                 return -NF_ACCEPT;
 163         }
 164
 165         ctinfo = IP_CT_RELATED;
 166
 167         h = nf_conntrack_find_get(net, nf_ct_zone_tmpl(tmpl, skb, &tmp),
 168                                   &intuple);
 169         if (!h) {
 170                 pr_debug("icmpv6_error: no match\n");
 171                 return -NF_ACCEPT;
 172         } else {
 173                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
 174                         ctinfo += IP_CT_IS_REPLY;
 175         }
 176
 177         /* Update skb to refer to this connection */
 178         nf_ct_set(skb, nf_ct_tuplehash_to_ctrack(h), ctinfo);
 179         return NF_ACCEPT;
 180 }
 181
 182 static void icmpv6_error_log(const struct sk_buff *skb,
 183                              const struct nf_hook_state *state,
 184                              const char *msg)
 185 {
 186         nf_l4proto_log_invalid(skb, state->net, state->pf,
 187                                IPPROTO_ICMPV6, "%s", msg);
 188 }
 189
 190 int nf_conntrack_icmpv6_error(struct nf_conn *tmpl,
 191                               struct sk_buff *skb,
 192                               unsigned int dataoff,
 193                               const struct nf_hook_state *state)
 194 {
 195         const struct icmp6hdr *icmp6h;
 196         struct icmp6hdr _ih;
 197         int type;
 198
 199         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 200         if (icmp6h == NULL) {
 201                 icmpv6_error_log(skb, state, "short packet");
 202                 return -NF_ACCEPT;
 203         }
 204
 205         if (state->hook == NF_INET_PRE_ROUTING &&
 206             state->net->ct.sysctl_checksum &&
 207             nf_ip6_checksum(skb, state->hook, dataoff, IPPROTO_ICMPV6)) {
 208                 icmpv6_error_log(skb, state, "ICMPv6 checksum failed");
 209                 return -NF_ACCEPT;
 210         }
 211
 212         type = icmp6h->icmp6_type - 130;
 213         if (type >= 0 && type < sizeof(noct_valid_new) &&
 214             noct_valid_new[type]) {
 215                 nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
 216                 return NF_ACCEPT;
 217         }
 218
 219         /* is not error message ? */
 220         if (icmp6h->icmp6_type >= 128)
 221                 return NF_ACCEPT;
 222
 223         return icmpv6_error_message(state->net, tmpl, skb, dataoff);
 224 }
 225
 226 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 227
 228 #include <linux/netfilter/nfnetlink.h>
 229 #include <linux/netfilter/nfnetlink_conntrack.h>
 230 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
 231                                   const struct nf_conntrack_tuple *t)
 232 {
 233         if (nla_put_be16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id) ||
 234             nla_put_u8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type) ||
 235             nla_put_u8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code))
 236                 goto nla_put_failure;
 237         return 0;
 238
 239 nla_put_failure:
 240         return -1;
 241 }
 242
 243 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
 244         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
 245         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
 246         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
 247 };
 248
 249 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
 250                                 struct nf_conntrack_tuple *tuple)
 251 {
 252         if (!tb[CTA_PROTO_ICMPV6_TYPE] ||
 253             !tb[CTA_PROTO_ICMPV6_CODE] ||
 254             !tb[CTA_PROTO_ICMPV6_ID])
 255                 return -EINVAL;
 256
 257         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
 258         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
 259         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
 260
 261         if (tuple->dst.u.icmp.type < 128 ||
 262             tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
 263             !invmap[tuple->dst.u.icmp.type - 128])
 264                 return -EINVAL;
 265
 266         return 0;
 267 }
 268
 269 static unsigned int icmpv6_nlattr_tuple_size(void)
 270 {
 271         static unsigned int size __read_mostly;
 272
 273         if (!size)
 274                 size = nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
 275
 276         return size;
 277 }
 278 #endif
 279
 280 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 281
 282 #include <linux/netfilter/nfnetlink.h>
 283 #include <linux/netfilter/nfnetlink_cttimeout.h>
 284
 285 static int icmpv6_timeout_nlattr_to_obj(struct nlattr *tb[],
 286                                         struct net *net, void *data)
 287 {
 288         unsigned int *timeout = data;
 289         struct nf_icmp_net *in = icmpv6_pernet(net);
 290
 291         if (!timeout)
 292                 timeout = icmpv6_get_timeouts(net);
 293         if (tb[CTA_TIMEOUT_ICMPV6_TIMEOUT]) {
 294                 *timeout =
 295                     ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMPV6_TIMEOUT])) * HZ;
 296         } else {
 297                 /* Set default ICMPv6 timeout. */
 298                 *timeout = in->timeout;
 299         }
 300         return 0;
 301 }
 302
 303 static int
 304 icmpv6_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 305 {
 306         const unsigned int *timeout = data;
 307
 308         if (nla_put_be32(skb, CTA_TIMEOUT_ICMPV6_TIMEOUT, htonl(*timeout / HZ)))
 309                 goto nla_put_failure;
 310         return 0;
 311
 312 nla_put_failure:
 313         return -ENOSPC;
 314 }
 315
 316 static const struct nla_policy
 317 icmpv6_timeout_nla_policy[CTA_TIMEOUT_ICMPV6_MAX+1] = {
 318         [CTA_TIMEOUT_ICMPV6_TIMEOUT]    = { .type = NLA_U32 },
 319 };
 320 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 321
 322 #ifdef CONFIG_SYSCTL
 323 static struct ctl_table icmpv6_sysctl_table[] = {
 324         {
 325                 .procname       = "nf_conntrack_icmpv6_timeout",
 326                 .maxlen         = sizeof(unsigned int),
 327                 .mode           = 0644,
 328                 .proc_handler   = proc_dointvec_jiffies,
 329         },
 330         { }
 331 };
 332 #endif /* CONFIG_SYSCTL */
 333
 334 static int icmpv6_kmemdup_sysctl_table(struct nf_proto_net *pn,
 335                                        struct nf_icmp_net *in)
 336 {
 337 #ifdef CONFIG_SYSCTL
 338         pn->ctl_table = kmemdup(icmpv6_sysctl_table,
 339                                 sizeof(icmpv6_sysctl_table),
 340                                 GFP_KERNEL);
 341         if (!pn->ctl_table)
 342                 return -ENOMEM;
 343
 344         pn->ctl_table[0].data = &in->timeout;
 345 #endif
 346         return 0;
 347 }
 348
 349 static int icmpv6_init_net(struct net *net)
 350 {
 351         struct nf_icmp_net *in = icmpv6_pernet(net);
 352         struct nf_proto_net *pn = &in->pn;
 353
 354         in->timeout = nf_ct_icmpv6_timeout;
 355
 356         return icmpv6_kmemdup_sysctl_table(pn, in);
 357 }
 358
 359 static struct nf_proto_net *icmpv6_get_net_proto(struct net *net)
 360 {
 361         return &net->ct.nf_ct_proto.icmpv6.pn;
 362 }
 363
 364 const struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 =
 365 {
 366         .l4proto                = IPPROTO_ICMPV6,
 367         .pkt_to_tuple           = icmpv6_pkt_to_tuple,
 368         .invert_tuple           = icmpv6_invert_tuple,
 369         .packet                 = icmpv6_packet,
 370 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 371         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
 372         .nlattr_tuple_size      = icmpv6_nlattr_tuple_size,
 373         .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
 374         .nla_policy             = icmpv6_nla_policy,
 375 #endif
 376 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 377         .ctnl_timeout           = {
 378                 .nlattr_to_obj  = icmpv6_timeout_nlattr_to_obj,
 379                 .obj_to_nlattr  = icmpv6_timeout_obj_to_nlattr,
 380                 .nlattr_max     = CTA_TIMEOUT_ICMP_MAX,
 381                 .obj_size       = sizeof(unsigned int),
 382                 .nla_policy     = icmpv6_timeout_nla_policy,
 383         },
 384 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 385         .init_net               = icmpv6_init_net,
 386         .get_net_proto          = icmpv6_get_net_proto,
 387 };