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_conntrack_timeout.h>
  26 #include <net/netfilter/nf_log.h>
  27 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
  28 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
  29
  30 static const unsigned int udp_timeouts[UDP_CT_MAX] = {
  31         [UDP_CT_UNREPLIED]      = 30*HZ,
  32         [UDP_CT_REPLIED]        = 180*HZ,
  33 };
  34
  35 static inline struct nf_udp_net *udp_pernet(struct net *net)
  36 {
  37         return &net->ct.nf_ct_proto.udp;
  38 }
  39
  40 static unsigned int *udp_get_timeouts(struct net *net)
  41 {
  42         return udp_pernet(net)->timeouts;
  43 }
  44
  45 /* Returns verdict for packet, and may modify conntracktype */
  46 static int udp_packet(struct nf_conn *ct,
  47                       const struct sk_buff *skb,
  48                       unsigned int dataoff,
  49                       enum ip_conntrack_info ctinfo)
  50 {
  51         unsigned int *timeouts;
  52
  53         timeouts = nf_ct_timeout_lookup(ct);
  54         if (!timeouts)
  55                 timeouts = udp_get_timeouts(nf_ct_net(ct));
  56
  57         /* If we've seen traffic both ways, this is some kind of UDP
  58            stream.  Extend timeout. */
  59         if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
  60                 nf_ct_refresh_acct(ct, ctinfo, skb,
  61                                    timeouts[UDP_CT_REPLIED]);
  62                 /* Also, more likely to be important, and not a probe */
  63                 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
  64                         nf_conntrack_event_cache(IPCT_ASSURED, ct);
  65         } else {
  66                 nf_ct_refresh_acct(ct, ctinfo, skb,
  67                                    timeouts[UDP_CT_UNREPLIED]);
  68         }
  69         return NF_ACCEPT;
  70 }
  71
  72 /* Called when a new connection for this protocol found. */
  73 static bool udp_new(struct nf_conn *ct, const struct sk_buff *skb,
  74                     unsigned int dataoff)
  75 {
  76         return true;
  77 }
  78
  79 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
  80 static void udplite_error_log(const struct sk_buff *skb, struct net *net,
  81                               u8 pf, const char *msg)
  82 {
  83         nf_l4proto_log_invalid(skb, net, pf, IPPROTO_UDPLITE, "%s", msg);
  84 }
  85
  86 static int udplite_error(struct net *net, struct nf_conn *tmpl,
  87                          struct sk_buff *skb,
  88                          unsigned int dataoff,
  89                          u8 pf, unsigned int hooknum)
  90 {
  91         unsigned int udplen = skb->len - dataoff;
  92         const struct udphdr *hdr;
  93         struct udphdr _hdr;
  94         unsigned int cscov;
  95
  96         /* Header is too small? */
  97         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  98         if (!hdr) {
  99                 udplite_error_log(skb, net, pf, "short packet");
 100                 return -NF_ACCEPT;
 101         }
 102
 103         cscov = ntohs(hdr->len);
 104         if (cscov == 0) {
 105                 cscov = udplen;
 106         } else if (cscov < sizeof(*hdr) || cscov > udplen) {
 107                 udplite_error_log(skb, net, pf, "invalid checksum coverage");
 108                 return -NF_ACCEPT;
 109         }
 110
 111         /* UDPLITE mandates checksums */
 112         if (!hdr->check) {
 113                 udplite_error_log(skb, net, pf, "checksum missing");
 114                 return -NF_ACCEPT;
 115         }
 116
 117         /* Checksum invalid? Ignore. */
 118         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 119             nf_checksum_partial(skb, hooknum, dataoff, cscov, IPPROTO_UDP,
 120                                 pf)) {
 121                 udplite_error_log(skb, net, pf, "bad checksum");
 122                 return -NF_ACCEPT;
 123         }
 124
 125         return NF_ACCEPT;
 126 }
 127 #endif
 128
 129 static void udp_error_log(const struct sk_buff *skb, struct net *net,
 130                           u8 pf, const char *msg)
 131 {
 132         nf_l4proto_log_invalid(skb, net, pf, IPPROTO_UDP, "%s", msg);
 133 }
 134
 135 static int udp_error(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb,
 136                      unsigned int dataoff,
 137                      u_int8_t pf,
 138                      unsigned int hooknum)
 139 {
 140         unsigned int udplen = skb->len - dataoff;
 141         const struct udphdr *hdr;
 142         struct udphdr _hdr;
 143
 144         /* Header is too small? */
 145         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 146         if (hdr == NULL) {
 147                 udp_error_log(skb, net, pf, "short packet");
 148                 return -NF_ACCEPT;
 149         }
 150
 151         /* Truncated/malformed packets */
 152         if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
 153                 udp_error_log(skb, net, pf, "truncated/malformed packet");
 154                 return -NF_ACCEPT;
 155         }
 156
 157         /* Packet with no checksum */
 158         if (!hdr->check)
 159                 return NF_ACCEPT;
 160
 161         /* Checksum invalid? Ignore.
 162          * We skip checking packets on the outgoing path
 163          * because the checksum is assumed to be correct.
 164          * FIXME: Source route IP option packets --RR */
 165         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 166             nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
 167                 udp_error_log(skb, net, pf, "bad checksum");
 168                 return -NF_ACCEPT;
 169         }
 170
 171         return NF_ACCEPT;
 172 }
 173
 174 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 175
 176 #include <linux/netfilter/nfnetlink.h>
 177 #include <linux/netfilter/nfnetlink_cttimeout.h>
 178
 179 static int udp_timeout_nlattr_to_obj(struct nlattr *tb[],
 180                                      struct net *net, void *data)
 181 {
 182         unsigned int *timeouts = data;
 183         struct nf_udp_net *un = udp_pernet(net);
 184
 185         if (!timeouts)
 186                 timeouts = un->timeouts;
 187
 188         /* set default timeouts for UDP. */
 189         timeouts[UDP_CT_UNREPLIED] = un->timeouts[UDP_CT_UNREPLIED];
 190         timeouts[UDP_CT_REPLIED] = un->timeouts[UDP_CT_REPLIED];
 191
 192         if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) {
 193                 timeouts[UDP_CT_UNREPLIED] =
 194                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ;
 195         }
 196         if (tb[CTA_TIMEOUT_UDP_REPLIED]) {
 197                 timeouts[UDP_CT_REPLIED] =
 198                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ;
 199         }
 200         return 0;
 201 }
 202
 203 static int
 204 udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 205 {
 206         const unsigned int *timeouts = data;
 207
 208         if (nla_put_be32(skb, CTA_TIMEOUT_UDP_UNREPLIED,
 209                          htonl(timeouts[UDP_CT_UNREPLIED] / HZ)) ||
 210             nla_put_be32(skb, CTA_TIMEOUT_UDP_REPLIED,
 211                          htonl(timeouts[UDP_CT_REPLIED] / HZ)))
 212                 goto nla_put_failure;
 213         return 0;
 214
 215 nla_put_failure:
 216         return -ENOSPC;
 217 }
 218
 219 static const struct nla_policy
 220 udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = {
 221        [CTA_TIMEOUT_UDP_UNREPLIED]      = { .type = NLA_U32 },
 222        [CTA_TIMEOUT_UDP_REPLIED]        = { .type = NLA_U32 },
 223 };
 224 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 225
 226 #ifdef CONFIG_SYSCTL
 227 static struct ctl_table udp_sysctl_table[] = {
 228         {
 229                 .procname       = "nf_conntrack_udp_timeout",
 230                 .maxlen         = sizeof(unsigned int),
 231                 .mode           = 0644,
 232                 .proc_handler   = proc_dointvec_jiffies,
 233         },
 234         {
 235                 .procname       = "nf_conntrack_udp_timeout_stream",
 236                 .maxlen         = sizeof(unsigned int),
 237                 .mode           = 0644,
 238                 .proc_handler   = proc_dointvec_jiffies,
 239         },
 240         { }
 241 };
 242 #endif /* CONFIG_SYSCTL */
 243
 244 static int udp_kmemdup_sysctl_table(struct nf_proto_net *pn,
 245                                     struct nf_udp_net *un)
 246 {
 247 #ifdef CONFIG_SYSCTL
 248         if (pn->ctl_table)
 249                 return 0;
 250         pn->ctl_table = kmemdup(udp_sysctl_table,
 251                                 sizeof(udp_sysctl_table),
 252                                 GFP_KERNEL);
 253         if (!pn->ctl_table)
 254                 return -ENOMEM;
 255         pn->ctl_table[0].data = &un->timeouts[UDP_CT_UNREPLIED];
 256         pn->ctl_table[1].data = &un->timeouts[UDP_CT_REPLIED];
 257 #endif
 258         return 0;
 259 }
 260
 261 static int udp_init_net(struct net *net, u_int16_t proto)
 262 {
 263         struct nf_udp_net *un = udp_pernet(net);
 264         struct nf_proto_net *pn = &un->pn;
 265
 266         if (!pn->users) {
 267                 int i;
 268
 269                 for (i = 0; i < UDP_CT_MAX; i++)
 270                         un->timeouts[i] = udp_timeouts[i];
 271         }
 272
 273         return udp_kmemdup_sysctl_table(pn, un);
 274 }
 275
 276 static struct nf_proto_net *udp_get_net_proto(struct net *net)
 277 {
 278         return &net->ct.nf_ct_proto.udp.pn;
 279 }
 280
 281 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udp4 =
 282 {
 283         .l3proto                = PF_INET,
 284         .l4proto                = IPPROTO_UDP,
 285         .allow_clash            = true,
 286         .packet                 = udp_packet,
 287         .new                    = udp_new,
 288         .error                  = udp_error,
 289 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 290         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 291         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 292         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 293         .nla_policy             = nf_ct_port_nla_policy,
 294 #endif
 295 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 296         .ctnl_timeout           = {
 297                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 298                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 299                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 300                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 301                 .nla_policy     = udp_timeout_nla_policy,
 302         },
 303 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 304         .init_net               = udp_init_net,
 305         .get_net_proto          = udp_get_net_proto,
 306 };
 307 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp4);
 308
 309 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
 310 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite4 =
 311 {
 312         .l3proto                = PF_INET,
 313         .l4proto                = IPPROTO_UDPLITE,
 314         .allow_clash            = true,
 315         .packet                 = udp_packet,
 316         .new                    = udp_new,
 317         .error                  = udplite_error,
 318 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 319         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 320         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 321         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 322         .nla_policy             = nf_ct_port_nla_policy,
 323 #endif
 324 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 325         .ctnl_timeout           = {
 326                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 327                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 328                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 329                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 330                 .nla_policy     = udp_timeout_nla_policy,
 331         },
 332 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 333         .init_net               = udp_init_net,
 334         .get_net_proto          = udp_get_net_proto,
 335 };
 336 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udplite4);
 337 #endif
 338
 339 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udp6 =
 340 {
 341         .l3proto                = PF_INET6,
 342         .l4proto                = IPPROTO_UDP,
 343         .allow_clash            = true,
 344         .packet                 = udp_packet,
 345         .new                    = udp_new,
 346         .error                  = udp_error,
 347 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 348         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 349         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 350         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 351         .nla_policy             = nf_ct_port_nla_policy,
 352 #endif
 353 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 354         .ctnl_timeout           = {
 355                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 356                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 357                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 358                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 359                 .nla_policy     = udp_timeout_nla_policy,
 360         },
 361 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 362         .init_net               = udp_init_net,
 363         .get_net_proto          = udp_get_net_proto,
 364 };
 365 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp6);
 366
 367 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
 368 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite6 =
 369 {
 370         .l3proto                = PF_INET6,
 371         .l4proto                = IPPROTO_UDPLITE,
 372         .allow_clash            = true,
 373         .packet                 = udp_packet,
 374         .new                    = udp_new,
 375         .error                  = udplite_error,
 376 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 377         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 378         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 379         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 380         .nla_policy             = nf_ct_port_nla_policy,
 381 #endif
 382 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 383         .ctnl_timeout           = {
 384                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 385                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 386                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 387                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 388                 .nla_policy     = udp_timeout_nla_policy,
 389         },
 390 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 391         .init_net               = udp_init_net,
 392         .get_net_proto          = udp_get_net_proto,
 393 };
 394 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udplite6);
 395 #endif