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