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   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/ipv6/nf_conntrack_icmpv6.h>
  27 #include <net/netfilter/nf_log.h>
  28
  29 static unsigned int nf_ct_icmpv6_timeout __read_mostly = 30*HZ;
  30
  31 static bool icmpv6_pkt_to_tuple(const struct sk_buff *skb,
  32                                 unsigned int dataoff,
  33                                 struct nf_conntrack_tuple *tuple)
  34 {
  35         const struct icmp6hdr *hp;
  36         struct icmp6hdr _hdr;
  37
  38         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  39         if (hp == NULL)
  40                 return false;
  41         tuple->dst.u.icmp.type = hp->icmp6_type;
  42         tuple->src.u.icmp.id = hp->icmp6_identifier;
  43         tuple->dst.u.icmp.code = hp->icmp6_code;
  44
  45         return true;
  46 }
  47
  48 /* Add 1; spaces filled with 0. */
  49 static const u_int8_t invmap[] = {
  50         [ICMPV6_ECHO_REQUEST - 128]     = ICMPV6_ECHO_REPLY + 1,
  51         [ICMPV6_ECHO_REPLY - 128]       = ICMPV6_ECHO_REQUEST + 1,
  52         [ICMPV6_NI_QUERY - 128]         = ICMPV6_NI_REPLY + 1,
  53         [ICMPV6_NI_REPLY - 128]         = ICMPV6_NI_QUERY +1
  54 };
  55
  56 static const u_int8_t noct_valid_new[] = {
  57         [ICMPV6_MGM_QUERY - 130] = 1,
  58         [ICMPV6_MGM_REPORT -130] = 1,
  59         [ICMPV6_MGM_REDUCTION - 130] = 1,
  60         [NDISC_ROUTER_SOLICITATION - 130] = 1,
  61         [NDISC_ROUTER_ADVERTISEMENT - 130] = 1,
  62         [NDISC_NEIGHBOUR_SOLICITATION - 130] = 1,
  63         [NDISC_NEIGHBOUR_ADVERTISEMENT - 130] = 1,
  64         [ICMPV6_MLD2_REPORT - 130] = 1
  65 };
  66
  67 static bool icmpv6_invert_tuple(struct nf_conntrack_tuple *tuple,
  68                                 const struct nf_conntrack_tuple *orig)
  69 {
  70         int type = orig->dst.u.icmp.type - 128;
  71         if (type < 0 || type >= sizeof(invmap) || !invmap[type])
  72                 return false;
  73
  74         tuple->src.u.icmp.id   = orig->src.u.icmp.id;
  75         tuple->dst.u.icmp.type = invmap[type] - 1;
  76         tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
  77         return true;
  78 }
  79
  80 /* Print out the per-protocol part of the tuple. */
  81 static int icmpv6_print_tuple(struct seq_file *s,
  82                               const struct nf_conntrack_tuple *tuple)
  83 {
  84         return seq_printf(s, "type=%u code=%u id=%u ",
  85                           tuple->dst.u.icmp.type,
  86                           tuple->dst.u.icmp.code,
  87                           ntohs(tuple->src.u.icmp.id));
  88 }
  89
  90 /* Returns verdict for packet, or -1 for invalid. */
  91 static int icmpv6_packet(struct nf_conn *ct,
  92                        const struct sk_buff *skb,
  93                        unsigned int dataoff,
  94                        enum ip_conntrack_info ctinfo,
  95                        u_int8_t pf,
  96                        unsigned int hooknum)
  97 {
  98         /* Try to delete connection immediately after all replies:
  99            won't actually vanish as we still have skb, and del_timer
 100            means this will only run once even if count hits zero twice
 101            (theoretically possible with SMP) */
 102         if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
 103                 if (atomic_dec_and_test(&ct->proto.icmp.count))
 104                         nf_ct_kill_acct(ct, ctinfo, skb);
 105         } else {
 106                 atomic_inc(&ct->proto.icmp.count);
 107                 nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, ct);
 108                 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmpv6_timeout);
 109         }
 110
 111         return NF_ACCEPT;
 112 }
 113
 114 /* Called when a new connection for this protocol found. */
 115 static bool icmpv6_new(struct nf_conn *ct, const struct sk_buff *skb,
 116                        unsigned int dataoff)
 117 {
 118         static const u_int8_t valid_new[] = {
 119                 [ICMPV6_ECHO_REQUEST - 128] = 1,
 120                 [ICMPV6_NI_QUERY - 128] = 1
 121         };
 122         int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;
 123
 124         if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
 125                 /* Can't create a new ICMPv6 `conn' with this. */
 126                 pr_debug("icmpv6: can't create new conn with type %u\n",
 127                          type + 128);
 128                 nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
 129                 return false;
 130         }
 131         atomic_set(&ct->proto.icmp.count, 0);
 132         return true;
 133 }
 134
 135 static int
 136 icmpv6_error_message(struct net *net,
 137                      struct sk_buff *skb,
 138                      unsigned int icmp6off,
 139                      enum ip_conntrack_info *ctinfo,
 140                      unsigned int hooknum)
 141 {
 142         struct nf_conntrack_tuple intuple, origtuple;
 143         const struct nf_conntrack_tuple_hash *h;
 144         const struct nf_conntrack_l4proto *inproto;
 145
 146         NF_CT_ASSERT(skb->nfct == NULL);
 147
 148         /* Are they talking about one of our connections? */
 149         if (!nf_ct_get_tuplepr(skb,
 150                                skb_network_offset(skb)
 151                                 + sizeof(struct ipv6hdr)
 152                                 + sizeof(struct icmp6hdr),
 153                                PF_INET6, &origtuple)) {
 154                 pr_debug("icmpv6_error: Can't get tuple\n");
 155                 return -NF_ACCEPT;
 156         }
 157
 158         /* rcu_read_lock()ed by nf_hook_slow */
 159         inproto = __nf_ct_l4proto_find(PF_INET6, origtuple.dst.protonum);
 160
 161         /* Ordinarily, we'd expect the inverted tupleproto, but it's
 162            been preserved inside the ICMP. */
 163         if (!nf_ct_invert_tuple(&intuple, &origtuple,
 164                                 &nf_conntrack_l3proto_ipv6, inproto)) {
 165                 pr_debug("icmpv6_error: Can't invert tuple\n");
 166                 return -NF_ACCEPT;
 167         }
 168
 169         *ctinfo = IP_CT_RELATED;
 170
 171         h = nf_conntrack_find_get(net, &intuple);
 172         if (!h) {
 173                 pr_debug("icmpv6_error: no match\n");
 174                 return -NF_ACCEPT;
 175         } else {
 176                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
 177                         *ctinfo += IP_CT_IS_REPLY;
 178         }
 179
 180         /* Update skb to refer to this connection */
 181         skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
 182         skb->nfctinfo = *ctinfo;
 183         return -NF_ACCEPT;
 184 }
 185
 186 static int
 187 icmpv6_error(struct net *net, struct sk_buff *skb, unsigned int dataoff,
 188              enum ip_conntrack_info *ctinfo, u_int8_t pf, unsigned int hooknum)
 189 {
 190         const struct icmp6hdr *icmp6h;
 191         struct icmp6hdr _ih;
 192         int type;
 193
 194         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 195         if (icmp6h == NULL) {
 196                 if (LOG_INVALID(net, IPPROTO_ICMPV6))
 197                 nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 198                               "nf_ct_icmpv6: short packet ");
 199                 return -NF_ACCEPT;
 200         }
 201
 202         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 203             nf_ip6_checksum(skb, hooknum, dataoff, IPPROTO_ICMPV6)) {
 204                 nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 205                               "nf_ct_icmpv6: ICMPv6 checksum failed\n");
 206                 return -NF_ACCEPT;
 207         }
 208
 209         type = icmp6h->icmp6_type - 130;
 210         if (type >= 0 && type < sizeof(noct_valid_new) &&
 211             noct_valid_new[type]) {
 212                 skb->nfct = &nf_conntrack_untracked.ct_general;
 213                 skb->nfctinfo = IP_CT_NEW;
 214                 nf_conntrack_get(skb->nfct);
 215                 return NF_ACCEPT;
 216         }
 217
 218         /* is not error message ? */
 219         if (icmp6h->icmp6_type >= 128)
 220                 return NF_ACCEPT;
 221
 222         return icmpv6_error_message(net, skb, dataoff, ctinfo, hooknum);
 223 }
 224
 225 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 226
 227 #include <linux/netfilter/nfnetlink.h>
 228 #include <linux/netfilter/nfnetlink_conntrack.h>
 229 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
 230                                   const struct nf_conntrack_tuple *t)
 231 {
 232         NLA_PUT_BE16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id);
 233         NLA_PUT_U8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type);
 234         NLA_PUT_U8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code);
 235
 236         return 0;
 237
 238 nla_put_failure:
 239         return -1;
 240 }
 241
 242 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
 243         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
 244         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
 245         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
 246 };
 247
 248 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
 249                                 struct nf_conntrack_tuple *tuple)
 250 {
 251         if (!tb[CTA_PROTO_ICMPV6_TYPE]
 252             || !tb[CTA_PROTO_ICMPV6_CODE]
 253             || !tb[CTA_PROTO_ICMPV6_ID])
 254                 return -EINVAL;
 255
 256         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
 257         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
 258         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
 259
 260         if (tuple->dst.u.icmp.type < 128
 261             || tuple->dst.u.icmp.type - 128 >= sizeof(invmap)
 262             || !invmap[tuple->dst.u.icmp.type - 128])
 263                 return -EINVAL;
 264
 265         return 0;
 266 }
 267 #endif
 268
 269 #ifdef CONFIG_SYSCTL
 270 static struct ctl_table_header *icmpv6_sysctl_header;
 271 static struct ctl_table icmpv6_sysctl_table[] = {
 272         {
 273                 .procname       = "nf_conntrack_icmpv6_timeout",
 274                 .data           = &nf_ct_icmpv6_timeout,
 275                 .maxlen         = sizeof(unsigned int),
 276                 .mode           = 0644,
 277                 .proc_handler   = proc_dointvec_jiffies,
 278         },
 279         {
 280                 .ctl_name       = 0
 281         }
 282 };
 283 #endif /* CONFIG_SYSCTL */
 284
 285 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 __read_mostly =
 286 {
 287         .l3proto                = PF_INET6,
 288         .l4proto                = IPPROTO_ICMPV6,
 289         .name                   = "icmpv6",
 290         .pkt_to_tuple           = icmpv6_pkt_to_tuple,
 291         .invert_tuple           = icmpv6_invert_tuple,
 292         .print_tuple            = icmpv6_print_tuple,
 293         .packet                 = icmpv6_packet,
 294         .new                    = icmpv6_new,
 295         .error                  = icmpv6_error,
 296 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 297         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
 298         .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
 299         .nla_policy             = icmpv6_nla_policy,
 300 #endif
 301 #ifdef CONFIG_SYSCTL
 302         .ctl_table_header       = &icmpv6_sysctl_header,
 303         .ctl_table              = icmpv6_sysctl_table,
 304 #endif
 305 };