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 const 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 static unsigned int *udp_get_timeouts(struct net *net)
  67 {
  68         return udp_pernet(net)->timeouts;
  69 }
  70
  71 /* Returns verdict for packet, and may modify conntracktype */
  72 static int udp_packet(struct nf_conn *ct,
  73                       const struct sk_buff *skb,
  74                       unsigned int dataoff,
  75                       enum ip_conntrack_info ctinfo,
  76                       unsigned int *timeouts)
  77 {
  78         /* If we've seen traffic both ways, this is some kind of UDP
  79            stream.  Extend timeout. */
  80         if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
  81                 nf_ct_refresh_acct(ct, ctinfo, skb,
  82                                    timeouts[UDP_CT_REPLIED]);
  83                 /* Also, more likely to be important, and not a probe */
  84                 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
  85                         nf_conntrack_event_cache(IPCT_ASSURED, ct);
  86         } else {
  87                 nf_ct_refresh_acct(ct, ctinfo, skb,
  88                                    timeouts[UDP_CT_UNREPLIED]);
  89         }
  90         return NF_ACCEPT;
  91 }
  92
  93 /* Called when a new connection for this protocol found. */
  94 static bool udp_new(struct nf_conn *ct, const struct sk_buff *skb,
  95                     unsigned int dataoff, unsigned int *timeouts)
  96 {
  97         return true;
  98 }
  99
 100 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
 101 static void udplite_error_log(const struct sk_buff *skb, struct net *net,
 102                               u8 pf, const char *msg)
 103 {
 104         nf_l4proto_log_invalid(skb, net, pf, IPPROTO_UDPLITE, "%s", msg);
 105 }
 106
 107 static int udplite_error(struct net *net, struct nf_conn *tmpl,
 108                          struct sk_buff *skb,
 109                          unsigned int dataoff,
 110                          u8 pf, unsigned int hooknum)
 111 {
 112         unsigned int udplen = skb->len - dataoff;
 113         const struct udphdr *hdr;
 114         struct udphdr _hdr;
 115         unsigned int cscov;
 116
 117         /* Header is too small? */
 118         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 119         if (!hdr) {
 120                 udplite_error_log(skb, net, pf, "short packet");
 121                 return -NF_ACCEPT;
 122         }
 123
 124         cscov = ntohs(hdr->len);
 125         if (cscov == 0) {
 126                 cscov = udplen;
 127         } else if (cscov < sizeof(*hdr) || cscov > udplen) {
 128                 udplite_error_log(skb, net, pf, "invalid checksum coverage");
 129                 return -NF_ACCEPT;
 130         }
 131
 132         /* UDPLITE mandates checksums */
 133         if (!hdr->check) {
 134                 udplite_error_log(skb, net, pf, "checksum missing");
 135                 return -NF_ACCEPT;
 136         }
 137
 138         /* Checksum invalid? Ignore. */
 139         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 140             nf_checksum_partial(skb, hooknum, dataoff, cscov, IPPROTO_UDP,
 141                                 pf)) {
 142                 udplite_error_log(skb, net, pf, "bad checksum");
 143                 return -NF_ACCEPT;
 144         }
 145
 146         return NF_ACCEPT;
 147 }
 148 #endif
 149
 150 static void udp_error_log(const struct sk_buff *skb, struct net *net,
 151                           u8 pf, const char *msg)
 152 {
 153         nf_l4proto_log_invalid(skb, net, pf, IPPROTO_UDP, "%s", msg);
 154 }
 155
 156 static int udp_error(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb,
 157                      unsigned int dataoff,
 158                      u_int8_t pf,
 159                      unsigned int hooknum)
 160 {
 161         unsigned int udplen = skb->len - dataoff;
 162         const struct udphdr *hdr;
 163         struct udphdr _hdr;
 164
 165         /* Header is too small? */
 166         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 167         if (hdr == NULL) {
 168                 udp_error_log(skb, net, pf, "short packet");
 169                 return -NF_ACCEPT;
 170         }
 171
 172         /* Truncated/malformed packets */
 173         if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
 174                 udp_error_log(skb, net, pf, "truncated/malformed packet");
 175                 return -NF_ACCEPT;
 176         }
 177
 178         /* Packet with no checksum */
 179         if (!hdr->check)
 180                 return NF_ACCEPT;
 181
 182         /* Checksum invalid? Ignore.
 183          * We skip checking packets on the outgoing path
 184          * because the checksum is assumed to be correct.
 185          * FIXME: Source route IP option packets --RR */
 186         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 187             nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
 188                 udp_error_log(skb, net, pf, "bad checksum");
 189                 return -NF_ACCEPT;
 190         }
 191
 192         return NF_ACCEPT;
 193 }
 194
 195 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 196
 197 #include <linux/netfilter/nfnetlink.h>
 198 #include <linux/netfilter/nfnetlink_cttimeout.h>
 199
 200 static int udp_timeout_nlattr_to_obj(struct nlattr *tb[],
 201                                      struct net *net, void *data)
 202 {
 203         unsigned int *timeouts = data;
 204         struct nf_udp_net *un = udp_pernet(net);
 205
 206         /* set default timeouts for UDP. */
 207         timeouts[UDP_CT_UNREPLIED] = un->timeouts[UDP_CT_UNREPLIED];
 208         timeouts[UDP_CT_REPLIED] = un->timeouts[UDP_CT_REPLIED];
 209
 210         if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) {
 211                 timeouts[UDP_CT_UNREPLIED] =
 212                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ;
 213         }
 214         if (tb[CTA_TIMEOUT_UDP_REPLIED]) {
 215                 timeouts[UDP_CT_REPLIED] =
 216                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ;
 217         }
 218         return 0;
 219 }
 220
 221 static int
 222 udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 223 {
 224         const unsigned int *timeouts = data;
 225
 226         if (nla_put_be32(skb, CTA_TIMEOUT_UDP_UNREPLIED,
 227                          htonl(timeouts[UDP_CT_UNREPLIED] / HZ)) ||
 228             nla_put_be32(skb, CTA_TIMEOUT_UDP_REPLIED,
 229                          htonl(timeouts[UDP_CT_REPLIED] / HZ)))
 230                 goto nla_put_failure;
 231         return 0;
 232
 233 nla_put_failure:
 234         return -ENOSPC;
 235 }
 236
 237 static const struct nla_policy
 238 udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = {
 239        [CTA_TIMEOUT_UDP_UNREPLIED]      = { .type = NLA_U32 },
 240        [CTA_TIMEOUT_UDP_REPLIED]        = { .type = NLA_U32 },
 241 };
 242 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 243
 244 #ifdef CONFIG_SYSCTL
 245 static struct ctl_table udp_sysctl_table[] = {
 246         {
 247                 .procname       = "nf_conntrack_udp_timeout",
 248                 .maxlen         = sizeof(unsigned int),
 249                 .mode           = 0644,
 250                 .proc_handler   = proc_dointvec_jiffies,
 251         },
 252         {
 253                 .procname       = "nf_conntrack_udp_timeout_stream",
 254                 .maxlen         = sizeof(unsigned int),
 255                 .mode           = 0644,
 256                 .proc_handler   = proc_dointvec_jiffies,
 257         },
 258         { }
 259 };
 260 #endif /* CONFIG_SYSCTL */
 261
 262 static int udp_kmemdup_sysctl_table(struct nf_proto_net *pn,
 263                                     struct nf_udp_net *un)
 264 {
 265 #ifdef CONFIG_SYSCTL
 266         if (pn->ctl_table)
 267                 return 0;
 268         pn->ctl_table = kmemdup(udp_sysctl_table,
 269                                 sizeof(udp_sysctl_table),
 270                                 GFP_KERNEL);
 271         if (!pn->ctl_table)
 272                 return -ENOMEM;
 273         pn->ctl_table[0].data = &un->timeouts[UDP_CT_UNREPLIED];
 274         pn->ctl_table[1].data = &un->timeouts[UDP_CT_REPLIED];
 275 #endif
 276         return 0;
 277 }
 278
 279 static int udp_init_net(struct net *net, u_int16_t proto)
 280 {
 281         struct nf_udp_net *un = udp_pernet(net);
 282         struct nf_proto_net *pn = &un->pn;
 283
 284         if (!pn->users) {
 285                 int i;
 286
 287                 for (i = 0; i < UDP_CT_MAX; i++)
 288                         un->timeouts[i] = udp_timeouts[i];
 289         }
 290
 291         return udp_kmemdup_sysctl_table(pn, un);
 292 }
 293
 294 static struct nf_proto_net *udp_get_net_proto(struct net *net)
 295 {
 296         return &net->ct.nf_ct_proto.udp.pn;
 297 }
 298
 299 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udp4 =
 300 {
 301         .l3proto                = PF_INET,
 302         .l4proto                = IPPROTO_UDP,
 303         .allow_clash            = true,
 304         .pkt_to_tuple           = udp_pkt_to_tuple,
 305         .invert_tuple           = udp_invert_tuple,
 306         .packet                 = udp_packet,
 307         .get_timeouts           = udp_get_timeouts,
 308         .new                    = udp_new,
 309         .error                  = udp_error,
 310 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 311         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 312         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 313         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 314         .nla_policy             = nf_ct_port_nla_policy,
 315 #endif
 316 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 317         .ctnl_timeout           = {
 318                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 319                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 320                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 321                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 322                 .nla_policy     = udp_timeout_nla_policy,
 323         },
 324 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 325         .init_net               = udp_init_net,
 326         .get_net_proto          = udp_get_net_proto,
 327 };
 328 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp4);
 329
 330 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
 331 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite4 =
 332 {
 333         .l3proto                = PF_INET,
 334         .l4proto                = IPPROTO_UDPLITE,
 335         .allow_clash            = true,
 336         .pkt_to_tuple           = udp_pkt_to_tuple,
 337         .invert_tuple           = udp_invert_tuple,
 338         .packet                 = udp_packet,
 339         .get_timeouts           = udp_get_timeouts,
 340         .new                    = udp_new,
 341         .error                  = udplite_error,
 342 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 343         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 344         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 345         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 346         .nla_policy             = nf_ct_port_nla_policy,
 347 #endif
 348 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 349         .ctnl_timeout           = {
 350                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 351                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 352                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 353                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 354                 .nla_policy     = udp_timeout_nla_policy,
 355         },
 356 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 357         .init_net               = udp_init_net,
 358         .get_net_proto          = udp_get_net_proto,
 359 };
 360 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udplite4);
 361 #endif
 362
 363 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udp6 =
 364 {
 365         .l3proto                = PF_INET6,
 366         .l4proto                = IPPROTO_UDP,
 367         .allow_clash            = true,
 368         .pkt_to_tuple           = udp_pkt_to_tuple,
 369         .invert_tuple           = udp_invert_tuple,
 370         .packet                 = udp_packet,
 371         .get_timeouts           = udp_get_timeouts,
 372         .new                    = udp_new,
 373         .error                  = udp_error,
 374 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 375         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 376         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 377         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 378         .nla_policy             = nf_ct_port_nla_policy,
 379 #endif
 380 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 381         .ctnl_timeout           = {
 382                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 383                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 384                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 385                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 386                 .nla_policy     = udp_timeout_nla_policy,
 387         },
 388 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 389         .init_net               = udp_init_net,
 390         .get_net_proto          = udp_get_net_proto,
 391 };
 392 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp6);
 393
 394 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
 395 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite6 =
 396 {
 397         .l3proto                = PF_INET6,
 398         .l4proto                = IPPROTO_UDPLITE,
 399         .allow_clash            = true,
 400         .pkt_to_tuple           = udp_pkt_to_tuple,
 401         .invert_tuple           = udp_invert_tuple,
 402         .packet                 = udp_packet,
 403         .get_timeouts           = udp_get_timeouts,
 404         .new                    = udp_new,
 405         .error                  = udplite_error,
 406 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 407         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 408         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 409         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 410         .nla_policy             = nf_ct_port_nla_policy,
 411 #endif
 412 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 413         .ctnl_timeout           = {
 414                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 415                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 416                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 417                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 418                 .nla_policy     = udp_timeout_nla_policy,
 419         },
 420 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 421         .init_net               = udp_init_net,
 422         .get_net_proto          = udp_get_net_proto,
 423 };
 424 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udplite6);
 425 #endif