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 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         /* Do not immediately delete the connection after the first
  99            successful reply to avoid excessive conntrackd traffic
 100            and also to handle correctly ICMP echo reply duplicates. */
 101         nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmpv6_timeout);
 102
 103         return NF_ACCEPT;
 104 }
 105
 106 /* Called when a new connection for this protocol found. */
 107 static bool icmpv6_new(struct nf_conn *ct, const struct sk_buff *skb,
 108                        unsigned int dataoff)
 109 {
 110         static const u_int8_t valid_new[] = {
 111                 [ICMPV6_ECHO_REQUEST - 128] = 1,
 112                 [ICMPV6_NI_QUERY - 128] = 1
 113         };
 114         int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;
 115
 116         if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
 117                 /* Can't create a new ICMPv6 `conn' with this. */
 118                 pr_debug("icmpv6: can't create new conn with type %u\n",
 119                          type + 128);
 120                 nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
 121                 if (LOG_INVALID(nf_ct_net(ct), IPPROTO_ICMPV6))
 122                         nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 123                                       "nf_ct_icmpv6: invalid new with type %d ",
 124                                       type + 128);
 125                 return false;
 126         }
 127         return true;
 128 }
 129
 130 static int
 131 icmpv6_error_message(struct net *net,
 132                      struct sk_buff *skb,
 133                      unsigned int icmp6off,
 134                      enum ip_conntrack_info *ctinfo,
 135                      unsigned int hooknum)
 136 {
 137         struct nf_conntrack_tuple intuple, origtuple;
 138         const struct nf_conntrack_tuple_hash *h;
 139         const struct nf_conntrack_l4proto *inproto;
 140
 141         NF_CT_ASSERT(skb->nfct == NULL);
 142
 143         /* Are they talking about one of our connections? */
 144         if (!nf_ct_get_tuplepr(skb,
 145                                skb_network_offset(skb)
 146                                 + sizeof(struct ipv6hdr)
 147                                 + sizeof(struct icmp6hdr),
 148                                PF_INET6, &origtuple)) {
 149                 pr_debug("icmpv6_error: Can't get tuple\n");
 150                 return -NF_ACCEPT;
 151         }
 152
 153         /* rcu_read_lock()ed by nf_hook_slow */
 154         inproto = __nf_ct_l4proto_find(PF_INET6, origtuple.dst.protonum);
 155
 156         /* Ordinarily, we'd expect the inverted tupleproto, but it's
 157            been preserved inside the ICMP. */
 158         if (!nf_ct_invert_tuple(&intuple, &origtuple,
 159                                 &nf_conntrack_l3proto_ipv6, inproto)) {
 160                 pr_debug("icmpv6_error: Can't invert tuple\n");
 161                 return -NF_ACCEPT;
 162         }
 163
 164         *ctinfo = IP_CT_RELATED;
 165
 166         h = nf_conntrack_find_get(net, &intuple);
 167         if (!h) {
 168                 pr_debug("icmpv6_error: no match\n");
 169                 return -NF_ACCEPT;
 170         } else {
 171                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
 172                         *ctinfo += IP_CT_IS_REPLY;
 173         }
 174
 175         /* Update skb to refer to this connection */
 176         skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
 177         skb->nfctinfo = *ctinfo;
 178         return -NF_ACCEPT;
 179 }
 180
 181 static int
 182 icmpv6_error(struct net *net, struct sk_buff *skb, unsigned int dataoff,
 183              enum ip_conntrack_info *ctinfo, u_int8_t pf, unsigned int hooknum)
 184 {
 185         const struct icmp6hdr *icmp6h;
 186         struct icmp6hdr _ih;
 187         int type;
 188
 189         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
 190         if (icmp6h == NULL) {
 191                 if (LOG_INVALID(net, IPPROTO_ICMPV6))
 192                 nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 193                               "nf_ct_icmpv6: short packet ");
 194                 return -NF_ACCEPT;
 195         }
 196
 197         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 198             nf_ip6_checksum(skb, hooknum, dataoff, IPPROTO_ICMPV6)) {
 199                 if (LOG_INVALID(net, IPPROTO_ICMPV6))
 200                         nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
 201                                       "nf_ct_icmpv6: 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                 skb->nfct = &nf_conntrack_untracked.ct_general;
 209                 skb->nfctinfo = IP_CT_NEW;
 210                 nf_conntrack_get(skb->nfct);
 211                 return NF_ACCEPT;
 212         }
 213
 214         /* is not error message ? */
 215         if (icmp6h->icmp6_type >= 128)
 216                 return NF_ACCEPT;
 217
 218         return icmpv6_error_message(net, skb, dataoff, ctinfo, hooknum);
 219 }
 220
 221 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 222
 223 #include <linux/netfilter/nfnetlink.h>
 224 #include <linux/netfilter/nfnetlink_conntrack.h>
 225 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
 226                                   const struct nf_conntrack_tuple *t)
 227 {
 228         NLA_PUT_BE16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id);
 229         NLA_PUT_U8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type);
 230         NLA_PUT_U8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code);
 231
 232         return 0;
 233
 234 nla_put_failure:
 235         return -1;
 236 }
 237
 238 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
 239         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
 240         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
 241         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
 242 };
 243
 244 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
 245                                 struct nf_conntrack_tuple *tuple)
 246 {
 247         if (!tb[CTA_PROTO_ICMPV6_TYPE]
 248             || !tb[CTA_PROTO_ICMPV6_CODE]
 249             || !tb[CTA_PROTO_ICMPV6_ID])
 250                 return -EINVAL;
 251
 252         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
 253         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
 254         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
 255
 256         if (tuple->dst.u.icmp.type < 128
 257             || tuple->dst.u.icmp.type - 128 >= sizeof(invmap)
 258             || !invmap[tuple->dst.u.icmp.type - 128])
 259                 return -EINVAL;
 260
 261         return 0;
 262 }
 263
 264 static int icmpv6_nlattr_tuple_size(void)
 265 {
 266         return nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
 267 }
 268 #endif
 269
 270 #ifdef CONFIG_SYSCTL
 271 static struct ctl_table_header *icmpv6_sysctl_header;
 272 static struct ctl_table icmpv6_sysctl_table[] = {
 273         {
 274                 .procname       = "nf_conntrack_icmpv6_timeout",
 275                 .data           = &nf_ct_icmpv6_timeout,
 276                 .maxlen         = sizeof(unsigned int),
 277                 .mode           = 0644,
 278                 .proc_handler   = proc_dointvec_jiffies,
 279         },
 280         { }
 281 };
 282 #endif /* CONFIG_SYSCTL */
 283
 284 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 __read_mostly =
 285 {
 286         .l3proto                = PF_INET6,
 287         .l4proto                = IPPROTO_ICMPV6,
 288         .name                   = "icmpv6",
 289         .pkt_to_tuple           = icmpv6_pkt_to_tuple,
 290         .invert_tuple           = icmpv6_invert_tuple,
 291         .print_tuple            = icmpv6_print_tuple,
 292         .packet                 = icmpv6_packet,
 293         .new                    = icmpv6_new,
 294         .error                  = icmpv6_error,
 295 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 296         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
 297         .nlattr_tuple_size      = icmpv6_nlattr_tuple_size,
 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 };