release/src-rt/linux/linux-2.6/net/ipv4/netfilter/nf_conntrack_proto_icmp.c

   1 /* (C) 1999-2001 Paul `Rusty' Russell
   2  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   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
   9 #include <linux/types.h>
  10 #include <linux/timer.h>
  11 #include <linux/netfilter.h>
  12 #include <linux/in.h>
  13 #include <linux/icmp.h>
  14 #include <linux/seq_file.h>
  15 #include <net/ip.h>
  16 #include <net/checksum.h>
  17 #include <linux/netfilter_ipv4.h>
  18 #include <net/netfilter/nf_conntrack_tuple.h>
  19 #include <net/netfilter/nf_conntrack_l4proto.h>
  20 #include <net/netfilter/nf_conntrack_core.h>
  21
  22 static unsigned long nf_ct_icmp_timeout __read_mostly = 30*HZ;
  23
  24 #if 0
  25 #define DEBUGP printk
  26 #else
  27 #define DEBUGP(format, args...)
  28 #endif
  29
  30 static int icmp_pkt_to_tuple(const struct sk_buff *skb,
  31                              unsigned int dataoff,
  32                              struct nf_conntrack_tuple *tuple)
  33 {
  34         struct icmphdr _hdr, *hp;
  35
  36         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  37         if (hp == NULL)
  38                 return 0;
  39
  40         tuple->dst.u.icmp.type = hp->type;
  41         tuple->src.u.icmp.id = hp->un.echo.id;
  42         tuple->dst.u.icmp.code = hp->code;
  43
  44         return 1;
  45 }
  46
  47 /* Add 1; spaces filled with 0. */
  48 static const u_int8_t invmap[] = {
  49         [ICMP_ECHO] = ICMP_ECHOREPLY + 1,
  50         [ICMP_ECHOREPLY] = ICMP_ECHO + 1,
  51         [ICMP_TIMESTAMP] = ICMP_TIMESTAMPREPLY + 1,
  52         [ICMP_TIMESTAMPREPLY] = ICMP_TIMESTAMP + 1,
  53         [ICMP_INFO_REQUEST] = ICMP_INFO_REPLY + 1,
  54         [ICMP_INFO_REPLY] = ICMP_INFO_REQUEST + 1,
  55         [ICMP_ADDRESS] = ICMP_ADDRESSREPLY + 1,
  56         [ICMP_ADDRESSREPLY] = ICMP_ADDRESS + 1
  57 };
  58
  59 static int icmp_invert_tuple(struct nf_conntrack_tuple *tuple,
  60                              const struct nf_conntrack_tuple *orig)
  61 {
  62         if (orig->dst.u.icmp.type >= sizeof(invmap)
  63             || !invmap[orig->dst.u.icmp.type])
  64                 return 0;
  65
  66         tuple->src.u.icmp.id = orig->src.u.icmp.id;
  67         tuple->dst.u.icmp.type = invmap[orig->dst.u.icmp.type] - 1;
  68         tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
  69         return 1;
  70 }
  71
  72 /* Print out the per-protocol part of the tuple. */
  73 static int icmp_print_tuple(struct seq_file *s,
  74                             const struct nf_conntrack_tuple *tuple)
  75 {
  76         return seq_printf(s, "type=%u code=%u id=%u ",
  77                           tuple->dst.u.icmp.type,
  78                           tuple->dst.u.icmp.code,
  79                           ntohs(tuple->src.u.icmp.id));
  80 }
  81
  82 /* Returns verdict for packet, or -1 for invalid. */
  83 static int icmp_packet(struct nf_conn *ct,
  84                        const struct sk_buff *skb,
  85                        unsigned int dataoff,
  86                        enum ip_conntrack_info ctinfo,
  87                        int pf,
  88                        unsigned int hooknum)
  89 {
  90         /* Try to delete connection immediately after all replies:
  91            won't actually vanish as we still have skb, and del_timer
  92            means this will only run once even if count hits zero twice
  93            (theoretically possible with SMP) */
  94         if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY) {
  95                 if (atomic_dec_and_test(&ct->proto.icmp.count)
  96                     && del_timer(&ct->timeout))
  97                         ct->timeout.function((unsigned long)ct);
  98         } else {
  99                 atomic_inc(&ct->proto.icmp.count);
 100                 nf_conntrack_event_cache(IPCT_PROTOINFO_VOLATILE, skb);
 101                 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_icmp_timeout);
 102         }
 103
 104         return NF_ACCEPT;
 105 }
 106
 107 /* Called when a new connection for this protocol found. */
 108 static int icmp_new(struct nf_conn *conntrack,
 109                     const struct sk_buff *skb, unsigned int dataoff)
 110 {
 111         static const u_int8_t valid_new[] = {
 112                 [ICMP_ECHO] = 1,
 113                 [ICMP_TIMESTAMP] = 1,
 114                 [ICMP_INFO_REQUEST] = 1,
 115                 [ICMP_ADDRESS] = 1
 116         };
 117
 118         if (conntrack->tuplehash[0].tuple.dst.u.icmp.type >= sizeof(valid_new)
 119             || !valid_new[conntrack->tuplehash[0].tuple.dst.u.icmp.type]) {
 120                 /* Can't create a new ICMP `conn' with this. */
 121                 DEBUGP("icmp: can't create new conn with type %u\n",
 122                        conntrack->tuplehash[0].tuple.dst.u.icmp.type);
 123                 NF_CT_DUMP_TUPLE(&conntrack->tuplehash[0].tuple);
 124                 return 0;
 125         }
 126         atomic_set(&conntrack->proto.icmp.count, 0);
 127         return 1;
 128 }
 129
 130 extern struct nf_conntrack_l3proto nf_conntrack_l3proto_ipv4;
 131 /* Returns conntrack if it dealt with ICMP, and filled in skb fields */
 132 static int
 133 icmp_error_message(struct sk_buff *skb,
 134                  enum ip_conntrack_info *ctinfo,
 135                  unsigned int hooknum)
 136 {
 137         struct nf_conntrack_tuple innertuple, origtuple;
 138         struct {
 139                 struct icmphdr icmp;
 140                 struct iphdr ip;
 141         } _in, *inside;
 142         struct nf_conntrack_l4proto *innerproto;
 143         struct nf_conntrack_tuple_hash *h;
 144         int dataoff;
 145
 146         NF_CT_ASSERT(skb->nfct == NULL);
 147
 148         /* Not enough header? */
 149         inside = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_in), &_in);
 150         if (inside == NULL)
 151                 return -NF_ACCEPT;
 152
 153         /* Ignore ICMP's containing fragments (shouldn't happen) */
 154         if (inside->ip.frag_off & htons(IP_OFFSET)) {
 155                 DEBUGP("icmp_error_message: fragment of proto %u\n",
 156                        inside->ip.protocol);
 157                 return -NF_ACCEPT;
 158         }
 159
 160         /* rcu_read_lock()ed by nf_hook_slow */
 161         innerproto = __nf_ct_l4proto_find(PF_INET, inside->ip.protocol);
 162
 163         dataoff = ip_hdrlen(skb) + sizeof(inside->icmp);
 164         /* Are they talking about one of our connections? */
 165         if (!nf_ct_get_tuple(skb, dataoff, dataoff + inside->ip.ihl*4, PF_INET,
 166                              inside->ip.protocol, &origtuple,
 167                              &nf_conntrack_l3proto_ipv4, innerproto)) {
 168                 DEBUGP("icmp_error_message: ! get_tuple p=%u",
 169                        inside->ip.protocol);
 170                 return -NF_ACCEPT;
 171         }
 172
 173         /* Ordinarily, we'd expect the inverted tupleproto, but it's
 174            been preserved inside the ICMP. */
 175         if (!nf_ct_invert_tuple(&innertuple, &origtuple,
 176                                 &nf_conntrack_l3proto_ipv4, innerproto)) {
 177                 DEBUGP("icmp_error_message: no match\n");
 178                 return -NF_ACCEPT;
 179         }
 180
 181         *ctinfo = IP_CT_RELATED;
 182
 183         h = nf_conntrack_find_get(&innertuple, NULL);
 184         if (!h) {
 185                 DEBUGP("icmp_error_message: no match\n");
 186                 return -NF_ACCEPT;
 187         }
 188
 189         if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
 190                 *ctinfo += IP_CT_IS_REPLY;
 191
 192         /* Update skb to refer to this connection */
 193         skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
 194         skb->nfctinfo = *ctinfo;
 195         return -NF_ACCEPT;
 196 }
 197
 198 /* Small and modified version of icmp_rcv */
 199 static int
 200 icmp_error(struct sk_buff *skb, unsigned int dataoff,
 201            enum ip_conntrack_info *ctinfo, int pf, unsigned int hooknum)
 202 {
 203         struct icmphdr _ih, *icmph;
 204
 205         /* Not enough header? */
 206         icmph = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_ih), &_ih);
 207         if (icmph == NULL) {
 208                 if (LOG_INVALID(IPPROTO_ICMP))
 209                         nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
 210                                       "nf_ct_icmp: short packet ");
 211                 return -NF_ACCEPT;
 212         }
 213
 214         /* See ip_conntrack_proto_tcp.c */
 215         if (nf_conntrack_checksum && hooknum == NF_IP_PRE_ROUTING &&
 216             nf_ip_checksum(skb, hooknum, dataoff, 0)) {
 217                 if (LOG_INVALID(IPPROTO_ICMP))
 218                         nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
 219                                       "nf_ct_icmp: bad HW ICMP checksum ");
 220                 return -NF_ACCEPT;
 221         }
 222
 223         /*
 224          *      18 is the highest 'known' ICMP type. Anything else is a mystery
 225          *
 226          *      RFC 1122: 3.2.2  Unknown ICMP messages types MUST be silently
 227          *                discarded.
 228          */
 229         if (icmph->type > NR_ICMP_TYPES) {
 230                 if (LOG_INVALID(IPPROTO_ICMP))
 231                         nf_log_packet(PF_INET, 0, skb, NULL, NULL, NULL,
 232                                       "nf_ct_icmp: invalid ICMP type ");
 233                 return -NF_ACCEPT;
 234         }
 235
 236         /* Need to track icmp error message? */
 237         if (icmph->type != ICMP_DEST_UNREACH
 238             && icmph->type != ICMP_SOURCE_QUENCH
 239             && icmph->type != ICMP_TIME_EXCEEDED
 240             && icmph->type != ICMP_PARAMETERPROB
 241             && icmph->type != ICMP_REDIRECT)
 242                 return NF_ACCEPT;
 243
 244         return icmp_error_message(skb, ctinfo, hooknum);
 245 }
 246
 247 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 248
 249 #include <linux/netfilter/nfnetlink.h>
 250 #include <linux/netfilter/nfnetlink_conntrack.h>
 251
 252 static int icmp_tuple_to_nfattr(struct sk_buff *skb,
 253                                 const struct nf_conntrack_tuple *t)
 254 {
 255         NFA_PUT(skb, CTA_PROTO_ICMP_ID, sizeof(u_int16_t),
 256                 &t->src.u.icmp.id);
 257         NFA_PUT(skb, CTA_PROTO_ICMP_TYPE, sizeof(u_int8_t),
 258                 &t->dst.u.icmp.type);
 259         NFA_PUT(skb, CTA_PROTO_ICMP_CODE, sizeof(u_int8_t),
 260                 &t->dst.u.icmp.code);
 261
 262         return 0;
 263
 264 nfattr_failure:
 265         return -1;
 266 }
 267
 268 static const size_t cta_min_proto[CTA_PROTO_MAX] = {
 269         [CTA_PROTO_ICMP_TYPE-1] = sizeof(u_int8_t),
 270         [CTA_PROTO_ICMP_CODE-1] = sizeof(u_int8_t),
 271         [CTA_PROTO_ICMP_ID-1]   = sizeof(u_int16_t)
 272 };
 273
 274 static int icmp_nfattr_to_tuple(struct nfattr *tb[],
 275                                 struct nf_conntrack_tuple *tuple)
 276 {
 277         if (!tb[CTA_PROTO_ICMP_TYPE-1]
 278             || !tb[CTA_PROTO_ICMP_CODE-1]
 279             || !tb[CTA_PROTO_ICMP_ID-1])
 280                 return -EINVAL;
 281
 282         if (nfattr_bad_size(tb, CTA_PROTO_MAX, cta_min_proto))
 283                 return -EINVAL;
 284
 285         tuple->dst.u.icmp.type =
 286                         *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMP_TYPE-1]);
 287         tuple->dst.u.icmp.code =
 288                         *(u_int8_t *)NFA_DATA(tb[CTA_PROTO_ICMP_CODE-1]);
 289         tuple->src.u.icmp.id =
 290                         *(__be16 *)NFA_DATA(tb[CTA_PROTO_ICMP_ID-1]);
 291
 292         if (tuple->dst.u.icmp.type >= sizeof(invmap)
 293             || !invmap[tuple->dst.u.icmp.type])
 294                 return -EINVAL;
 295
 296         return 0;
 297 }
 298 #endif
 299
 300 #ifdef CONFIG_SYSCTL
 301 static struct ctl_table_header *icmp_sysctl_header;
 302 static struct ctl_table icmp_sysctl_table[] = {
 303         {
 304                 .ctl_name       = NET_NF_CONNTRACK_ICMP_TIMEOUT,
 305                 .procname       = "nf_conntrack_icmp_timeout",
 306                 .data           = &nf_ct_icmp_timeout,
 307                 .maxlen         = sizeof(unsigned int),
 308                 .mode           = 0644,
 309                 .proc_handler   = &proc_dointvec_jiffies,
 310         },
 311         {
 312                 .ctl_name = 0
 313         }
 314 };
 315 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 316 static struct ctl_table icmp_compat_sysctl_table[] = {
 317         {
 318                 .ctl_name       = NET_IPV4_NF_CONNTRACK_ICMP_TIMEOUT,
 319                 .procname       = "ip_conntrack_icmp_timeout",
 320                 .data           = &nf_ct_icmp_timeout,
 321                 .maxlen         = sizeof(unsigned int),
 322                 .mode           = 0644,
 323                 .proc_handler   = &proc_dointvec_jiffies,
 324         },
 325         {
 326                 .ctl_name = 0
 327         }
 328 };
 329 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 330 #endif /* CONFIG_SYSCTL */
 331
 332 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp =
 333 {
 334         .l3proto                = PF_INET,
 335         .l4proto                = IPPROTO_ICMP,
 336         .name                   = "icmp",
 337         .pkt_to_tuple           = icmp_pkt_to_tuple,
 338         .invert_tuple           = icmp_invert_tuple,
 339         .print_tuple            = icmp_print_tuple,
 340         .packet                 = icmp_packet,
 341         .new                    = icmp_new,
 342         .error                  = icmp_error,
 343         .destroy                = NULL,
 344         .me                     = NULL,
 345 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 346         .tuple_to_nfattr        = icmp_tuple_to_nfattr,
 347         .nfattr_to_tuple        = icmp_nfattr_to_tuple,
 348 #endif
 349 #ifdef CONFIG_SYSCTL
 350         .ctl_table_header       = &icmp_sysctl_header,
 351         .ctl_table              = icmp_sysctl_table,
 352 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 353         .ctl_compat_table       = icmp_compat_sysctl_table,
 354 #endif
 355 #endif
 356 };
 357 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_icmp);