net/netfilter/nf_conntrack_proto_udp.c

   1 /* (C) 1999-2001 Paul `Rusty' Russell
   2  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   3  * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/types.h>
  11 #include <linux/timer.h>
  12 #include <linux/module.h>
  13 #include <linux/udp.h>
  14 #include <linux/seq_file.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/ipv6.h>
  17 #include <net/ip6_checksum.h>
  18 #include <net/checksum.h>
  19
  20 #include <linux/netfilter.h>
  21 #include <linux/netfilter_ipv4.h>
  22 #include <linux/netfilter_ipv6.h>
  23 #include <net/netfilter/nf_conntrack_l4proto.h>
  24 #include <net/netfilter/nf_conntrack_ecache.h>
  25 #include <net/netfilter/nf_log.h>
  26 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
  27 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
  28
  29 static unsigned int udp_timeouts[UDP_CT_MAX] = {
  30         [UDP_CT_UNREPLIED]      = 30*HZ,
  31         [UDP_CT_REPLIED]        = 180*HZ,
  32 };
  33
  34 static inline struct nf_udp_net *udp_pernet(struct net *net)
  35 {
  36         return &net->ct.nf_ct_proto.udp;
  37 }
  38
  39 static bool udp_pkt_to_tuple(const struct sk_buff *skb,
  40                              unsigned int dataoff,
  41                              struct net *net,
  42                              struct nf_conntrack_tuple *tuple)
  43 {
  44         const struct udphdr *hp;
  45         struct udphdr _hdr;
  46
  47         /* Actually only need first 4 bytes to get ports. */
  48         hp = skb_header_pointer(skb, dataoff, 4, &_hdr);
  49         if (hp == NULL)
  50                 return false;
  51
  52         tuple->src.u.udp.port = hp->source;
  53         tuple->dst.u.udp.port = hp->dest;
  54
  55         return true;
  56 }
  57
  58 static bool udp_invert_tuple(struct nf_conntrack_tuple *tuple,
  59                              const struct nf_conntrack_tuple *orig)
  60 {
  61         tuple->src.u.udp.port = orig->dst.u.udp.port;
  62         tuple->dst.u.udp.port = orig->src.u.udp.port;
  63         return true;
  64 }
  65
  66 /* Print out the per-protocol part of the tuple. */
  67 static void udp_print_tuple(struct seq_file *s,
  68                             const struct nf_conntrack_tuple *tuple)
  69 {
  70         seq_printf(s, "sport=%hu dport=%hu ",
  71                    ntohs(tuple->src.u.udp.port),
  72                    ntohs(tuple->dst.u.udp.port));
  73 }
  74
  75 static unsigned int *udp_get_timeouts(struct net *net)
  76 {
  77         return udp_pernet(net)->timeouts;
  78 }
  79
  80 /* Returns verdict for packet, and may modify conntracktype */
  81 static int udp_packet(struct nf_conn *ct,
  82                       const struct sk_buff *skb,
  83                       unsigned int dataoff,
  84                       enum ip_conntrack_info ctinfo,
  85                       u_int8_t pf,
  86                       unsigned int hooknum,
  87                       unsigned int *timeouts)
  88 {
  89         /* If we've seen traffic both ways, this is some kind of UDP
  90            stream.  Extend timeout. */
  91         if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
  92                 nf_ct_refresh_acct(ct, ctinfo, skb,
  93                                    timeouts[UDP_CT_REPLIED]);
  94                 /* Also, more likely to be important, and not a probe */
  95                 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
  96                         nf_conntrack_event_cache(IPCT_ASSURED, ct);
  97         } else {
  98                 nf_ct_refresh_acct(ct, ctinfo, skb,
  99                                    timeouts[UDP_CT_UNREPLIED]);
 100         }
 101         return NF_ACCEPT;
 102 }
 103
 104 /* Called when a new connection for this protocol found. */
 105 static bool udp_new(struct nf_conn *ct, const struct sk_buff *skb,
 106                     unsigned int dataoff, unsigned int *timeouts)
 107 {
 108         return true;
 109 }
 110
 111 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
 112 static int udplite_error(struct net *net, struct nf_conn *tmpl,
 113                          struct sk_buff *skb,
 114                          unsigned int dataoff,
 115                          u8 pf, unsigned int hooknum)
 116 {
 117         unsigned int udplen = skb->len - dataoff;
 118         const struct udphdr *hdr;
 119         struct udphdr _hdr;
 120         unsigned int cscov;
 121
 122         /* Header is too small? */
 123         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 124         if (!hdr) {
 125                 if (LOG_INVALID(net, IPPROTO_UDPLITE))
 126                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 127                                       "nf_ct_udplite: short packet ");
 128                 return -NF_ACCEPT;
 129         }
 130
 131         cscov = ntohs(hdr->len);
 132         if (cscov == 0) {
 133                 cscov = udplen;
 134         } else if (cscov < sizeof(*hdr) || cscov > udplen) {
 135                 if (LOG_INVALID(net, IPPROTO_UDPLITE))
 136                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 137                                       "nf_ct_udplite: invalid checksum coverage ");
 138                 return -NF_ACCEPT;
 139         }
 140
 141         /* UDPLITE mandates checksums */
 142         if (!hdr->check) {
 143                 if (LOG_INVALID(net, IPPROTO_UDPLITE))
 144                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 145                                       "nf_ct_udplite: checksum missing ");
 146                 return -NF_ACCEPT;
 147         }
 148
 149         /* Checksum invalid? Ignore. */
 150         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 151             nf_checksum_partial(skb, hooknum, dataoff, cscov, IPPROTO_UDP,
 152                                 pf)) {
 153                 if (LOG_INVALID(net, IPPROTO_UDPLITE))
 154                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 155                                       "nf_ct_udplite: bad UDPLite checksum ");
 156                 return -NF_ACCEPT;
 157         }
 158
 159         return NF_ACCEPT;
 160 }
 161 #endif
 162
 163 static int udp_error(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb,
 164                      unsigned int dataoff,
 165                      u_int8_t pf,
 166                      unsigned int hooknum)
 167 {
 168         unsigned int udplen = skb->len - dataoff;
 169         const struct udphdr *hdr;
 170         struct udphdr _hdr;
 171
 172         /* Header is too small? */
 173         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 174         if (hdr == NULL) {
 175                 if (LOG_INVALID(net, IPPROTO_UDP))
 176                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 177                                       "nf_ct_udp: short packet ");
 178                 return -NF_ACCEPT;
 179         }
 180
 181         /* Truncated/malformed packets */
 182         if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
 183                 if (LOG_INVALID(net, IPPROTO_UDP))
 184                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 185                                 "nf_ct_udp: truncated/malformed packet ");
 186                 return -NF_ACCEPT;
 187         }
 188
 189         /* Packet with no checksum */
 190         if (!hdr->check)
 191                 return NF_ACCEPT;
 192
 193         /* Checksum invalid? Ignore.
 194          * We skip checking packets on the outgoing path
 195          * because the checksum is assumed to be correct.
 196          * FIXME: Source route IP option packets --RR */
 197         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 198             nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
 199                 if (LOG_INVALID(net, IPPROTO_UDP))
 200                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 201                                 "nf_ct_udp: bad UDP checksum ");
 202                 return -NF_ACCEPT;
 203         }
 204
 205         return NF_ACCEPT;
 206 }
 207
 208 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 209
 210 #include <linux/netfilter/nfnetlink.h>
 211 #include <linux/netfilter/nfnetlink_cttimeout.h>
 212
 213 static int udp_timeout_nlattr_to_obj(struct nlattr *tb[],
 214                                      struct net *net, void *data)
 215 {
 216         unsigned int *timeouts = data;
 217         struct nf_udp_net *un = udp_pernet(net);
 218
 219         /* set default timeouts for UDP. */
 220         timeouts[UDP_CT_UNREPLIED] = un->timeouts[UDP_CT_UNREPLIED];
 221         timeouts[UDP_CT_REPLIED] = un->timeouts[UDP_CT_REPLIED];
 222
 223         if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) {
 224                 timeouts[UDP_CT_UNREPLIED] =
 225                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ;
 226         }
 227         if (tb[CTA_TIMEOUT_UDP_REPLIED]) {
 228                 timeouts[UDP_CT_REPLIED] =
 229                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ;
 230         }
 231         return 0;
 232 }
 233
 234 static int
 235 udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 236 {
 237         const unsigned int *timeouts = data;
 238
 239         if (nla_put_be32(skb, CTA_TIMEOUT_UDP_UNREPLIED,
 240                          htonl(timeouts[UDP_CT_UNREPLIED] / HZ)) ||
 241             nla_put_be32(skb, CTA_TIMEOUT_UDP_REPLIED,
 242                          htonl(timeouts[UDP_CT_REPLIED] / HZ)))
 243                 goto nla_put_failure;
 244         return 0;
 245
 246 nla_put_failure:
 247         return -ENOSPC;
 248 }
 249
 250 static const struct nla_policy
 251 udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = {
 252        [CTA_TIMEOUT_UDP_UNREPLIED]      = { .type = NLA_U32 },
 253        [CTA_TIMEOUT_UDP_REPLIED]        = { .type = NLA_U32 },
 254 };
 255 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 256
 257 #ifdef CONFIG_SYSCTL
 258 static struct ctl_table udp_sysctl_table[] = {
 259         {
 260                 .procname       = "nf_conntrack_udp_timeout",
 261                 .maxlen         = sizeof(unsigned int),
 262                 .mode           = 0644,
 263                 .proc_handler   = proc_dointvec_jiffies,
 264         },
 265         {
 266                 .procname       = "nf_conntrack_udp_timeout_stream",
 267                 .maxlen         = sizeof(unsigned int),
 268                 .mode           = 0644,
 269                 .proc_handler   = proc_dointvec_jiffies,
 270         },
 271         { }
 272 };
 273 #endif /* CONFIG_SYSCTL */
 274
 275 static int udp_kmemdup_sysctl_table(struct nf_proto_net *pn,
 276                                     struct nf_udp_net *un)
 277 {
 278 #ifdef CONFIG_SYSCTL
 279         if (pn->ctl_table)
 280                 return 0;
 281         pn->ctl_table = kmemdup(udp_sysctl_table,
 282                                 sizeof(udp_sysctl_table),
 283                                 GFP_KERNEL);
 284         if (!pn->ctl_table)
 285                 return -ENOMEM;
 286         pn->ctl_table[0].data = &un->timeouts[UDP_CT_UNREPLIED];
 287         pn->ctl_table[1].data = &un->timeouts[UDP_CT_REPLIED];
 288 #endif
 289         return 0;
 290 }
 291
 292 static int udp_init_net(struct net *net, u_int16_t proto)
 293 {
 294         struct nf_udp_net *un = udp_pernet(net);
 295         struct nf_proto_net *pn = &un->pn;
 296
 297         if (!pn->users) {
 298                 int i;
 299
 300                 for (i = 0; i < UDP_CT_MAX; i++)
 301                         un->timeouts[i] = udp_timeouts[i];
 302         }
 303
 304         return udp_kmemdup_sysctl_table(pn, un);
 305 }
 306
 307 static struct nf_proto_net *udp_get_net_proto(struct net *net)
 308 {
 309         return &net->ct.nf_ct_proto.udp.pn;
 310 }
 311
 312 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp4 __read_mostly =
 313 {
 314         .l3proto                = PF_INET,
 315         .l4proto                = IPPROTO_UDP,
 316         .name                   = "udp",
 317         .allow_clash            = true,
 318         .pkt_to_tuple           = udp_pkt_to_tuple,
 319         .invert_tuple           = udp_invert_tuple,
 320         .print_tuple            = udp_print_tuple,
 321         .packet                 = udp_packet,
 322         .get_timeouts           = udp_get_timeouts,
 323         .new                    = udp_new,
 324         .error                  = udp_error,
 325 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 326         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 327         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 328         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 329         .nla_policy             = nf_ct_port_nla_policy,
 330 #endif
 331 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 332         .ctnl_timeout           = {
 333                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 334                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 335                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 336                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 337                 .nla_policy     = udp_timeout_nla_policy,
 338         },
 339 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 340         .init_net               = udp_init_net,
 341         .get_net_proto          = udp_get_net_proto,
 342 };
 343 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp4);
 344
 345 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
 346 struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite4 __read_mostly =
 347 {
 348         .l3proto                = PF_INET,
 349         .l4proto                = IPPROTO_UDPLITE,
 350         .name                   = "udplite",
 351         .allow_clash            = true,
 352         .pkt_to_tuple           = udp_pkt_to_tuple,
 353         .invert_tuple           = udp_invert_tuple,
 354         .print_tuple            = udp_print_tuple,
 355         .packet                 = udp_packet,
 356         .get_timeouts           = udp_get_timeouts,
 357         .new                    = udp_new,
 358         .error                  = udplite_error,
 359 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 360         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 361         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 362         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 363         .nla_policy             = nf_ct_port_nla_policy,
 364 #endif
 365 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 366         .ctnl_timeout           = {
 367                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 368                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 369                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 370                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 371                 .nla_policy     = udp_timeout_nla_policy,
 372         },
 373 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 374         .init_net               = udp_init_net,
 375         .get_net_proto          = udp_get_net_proto,
 376 };
 377 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udplite4);
 378 #endif
 379
 380 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp6 __read_mostly =
 381 {
 382         .l3proto                = PF_INET6,
 383         .l4proto                = IPPROTO_UDP,
 384         .name                   = "udp",
 385         .allow_clash            = true,
 386         .pkt_to_tuple           = udp_pkt_to_tuple,
 387         .invert_tuple           = udp_invert_tuple,
 388         .print_tuple            = udp_print_tuple,
 389         .packet                 = udp_packet,
 390         .get_timeouts           = udp_get_timeouts,
 391         .new                    = udp_new,
 392         .error                  = udp_error,
 393 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 394         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 395         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 396         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 397         .nla_policy             = nf_ct_port_nla_policy,
 398 #endif
 399 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 400         .ctnl_timeout           = {
 401                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 402                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 403                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 404                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 405                 .nla_policy     = udp_timeout_nla_policy,
 406         },
 407 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 408         .init_net               = udp_init_net,
 409         .get_net_proto          = udp_get_net_proto,
 410 };
 411 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp6);
 412
 413 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
 414 struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite6 __read_mostly =
 415 {
 416         .l3proto                = PF_INET6,
 417         .l4proto                = IPPROTO_UDPLITE,
 418         .name                   = "udplite",
 419         .allow_clash            = true,
 420         .pkt_to_tuple           = udp_pkt_to_tuple,
 421         .invert_tuple           = udp_invert_tuple,
 422         .print_tuple            = udp_print_tuple,
 423         .packet                 = udp_packet,
 424         .get_timeouts           = udp_get_timeouts,
 425         .new                    = udp_new,
 426         .error                  = udplite_error,
 427 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 428         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 429         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 430         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 431         .nla_policy             = nf_ct_port_nla_policy,
 432 #endif
 433 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 434         .ctnl_timeout           = {
 435                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 436                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 437                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 438                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 439                 .nla_policy     = udp_timeout_nla_policy,
 440         },
 441 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 442         .init_net               = udp_init_net,
 443         .get_net_proto          = udp_get_net_proto,
 444 };
 445 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udplite6);
 446 #endif