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 unsigned int *udp_get_timeouts(struct net *net)
  36 {
  37         return nf_udp_pernet(net)->timeouts;
  38 }
  39
  40 static void udp_error_log(const struct sk_buff *skb,
  41                           const struct nf_hook_state *state,
  42                           const char *msg)
  43 {
  44         nf_l4proto_log_invalid(skb, state->net, state->pf,
  45                                IPPROTO_UDP, "%s", msg);
  46 }
  47
  48 static bool udp_error(struct sk_buff *skb,
  49                       unsigned int dataoff,
  50                       const struct nf_hook_state *state)
  51 {
  52         unsigned int udplen = skb->len - dataoff;
  53         const struct udphdr *hdr;
  54         struct udphdr _hdr;
  55
  56         /* Header is too small? */
  57         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  58         if (!hdr) {
  59                 udp_error_log(skb, state, "short packet");
  60                 return true;
  61         }
  62
  63         /* Truncated/malformed packets */
  64         if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
  65                 udp_error_log(skb, state, "truncated/malformed packet");
  66                 return true;
  67         }
  68
  69         /* Packet with no checksum */
  70         if (!hdr->check)
  71                 return false;
  72
  73         /* Checksum invalid? Ignore.
  74          * We skip checking packets on the outgoing path
  75          * because the checksum is assumed to be correct.
  76          * FIXME: Source route IP option packets --RR */
  77         if (state->hook == NF_INET_PRE_ROUTING &&
  78             state->net->ct.sysctl_checksum &&
  79             nf_checksum(skb, state->hook, dataoff, IPPROTO_UDP, state->pf)) {
  80                 udp_error_log(skb, state, "bad checksum");
  81                 return true;
  82         }
  83
  84         return false;
  85 }
  86
  87 /* Returns verdict for packet, and may modify conntracktype */
  88 static int udp_packet(struct nf_conn *ct,
  89                       struct sk_buff *skb,
  90                       unsigned int dataoff,
  91                       enum ip_conntrack_info ctinfo,
  92                       const struct nf_hook_state *state)
  93 {
  94         unsigned int *timeouts;
  95
  96         if (udp_error(skb, dataoff, state))
  97                 return -NF_ACCEPT;
  98
  99         timeouts = nf_ct_timeout_lookup(ct);
 100         if (!timeouts)
 101                 timeouts = udp_get_timeouts(nf_ct_net(ct));
 102
 103         /* If we've seen traffic both ways, this is some kind of UDP
 104            stream.  Extend timeout. */
 105         if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
 106                 nf_ct_refresh_acct(ct, ctinfo, skb,
 107                                    timeouts[UDP_CT_REPLIED]);
 108                 /* Also, more likely to be important, and not a probe */
 109                 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
 110                         nf_conntrack_event_cache(IPCT_ASSURED, ct);
 111         } else {
 112                 nf_ct_refresh_acct(ct, ctinfo, skb,
 113                                    timeouts[UDP_CT_UNREPLIED]);
 114         }
 115         return NF_ACCEPT;
 116 }
 117
 118 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
 119 static void udplite_error_log(const struct sk_buff *skb,
 120                               const struct nf_hook_state *state,
 121                               const char *msg)
 122 {
 123         nf_l4proto_log_invalid(skb, state->net, state->pf,
 124                                IPPROTO_UDPLITE, "%s", msg);
 125 }
 126
 127 static bool udplite_error(struct sk_buff *skb,
 128                           unsigned int dataoff,
 129                           const struct nf_hook_state *state)
 130 {
 131         unsigned int udplen = skb->len - dataoff;
 132         const struct udphdr *hdr;
 133         struct udphdr _hdr;
 134         unsigned int cscov;
 135
 136         /* Header is too small? */
 137         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 138         if (!hdr) {
 139                 udplite_error_log(skb, state, "short packet");
 140                 return true;
 141         }
 142
 143         cscov = ntohs(hdr->len);
 144         if (cscov == 0) {
 145                 cscov = udplen;
 146         } else if (cscov < sizeof(*hdr) || cscov > udplen) {
 147                 udplite_error_log(skb, state, "invalid checksum coverage");
 148                 return true;
 149         }
 150
 151         /* UDPLITE mandates checksums */
 152         if (!hdr->check) {
 153                 udplite_error_log(skb, state, "checksum missing");
 154                 return true;
 155         }
 156
 157         /* Checksum invalid? Ignore. */
 158         if (state->hook == NF_INET_PRE_ROUTING &&
 159             state->net->ct.sysctl_checksum &&
 160             nf_checksum_partial(skb, state->hook, dataoff, cscov, IPPROTO_UDP,
 161                                 state->pf)) {
 162                 udplite_error_log(skb, state, "bad checksum");
 163                 return true;
 164         }
 165
 166         return false;
 167 }
 168
 169 /* Returns verdict for packet, and may modify conntracktype */
 170 static int udplite_packet(struct nf_conn *ct,
 171                           struct sk_buff *skb,
 172                           unsigned int dataoff,
 173                           enum ip_conntrack_info ctinfo,
 174                           const struct nf_hook_state *state)
 175 {
 176         unsigned int *timeouts;
 177
 178         if (udplite_error(skb, dataoff, state))
 179                 return -NF_ACCEPT;
 180
 181         timeouts = nf_ct_timeout_lookup(ct);
 182         if (!timeouts)
 183                 timeouts = udp_get_timeouts(nf_ct_net(ct));
 184
 185         /* If we've seen traffic both ways, this is some kind of UDP
 186            stream.  Extend timeout. */
 187         if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
 188                 nf_ct_refresh_acct(ct, ctinfo, skb,
 189                                    timeouts[UDP_CT_REPLIED]);
 190                 /* Also, more likely to be important, and not a probe */
 191                 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
 192                         nf_conntrack_event_cache(IPCT_ASSURED, ct);
 193         } else {
 194                 nf_ct_refresh_acct(ct, ctinfo, skb,
 195                                    timeouts[UDP_CT_UNREPLIED]);
 196         }
 197         return NF_ACCEPT;
 198 }
 199 #endif
 200
 201 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 202
 203 #include <linux/netfilter/nfnetlink.h>
 204 #include <linux/netfilter/nfnetlink_cttimeout.h>
 205
 206 static int udp_timeout_nlattr_to_obj(struct nlattr *tb[],
 207                                      struct net *net, void *data)
 208 {
 209         unsigned int *timeouts = data;
 210         struct nf_udp_net *un = nf_udp_pernet(net);
 211
 212         if (!timeouts)
 213                 timeouts = un->timeouts;
 214
 215         /* set default timeouts for UDP. */
 216         timeouts[UDP_CT_UNREPLIED] = un->timeouts[UDP_CT_UNREPLIED];
 217         timeouts[UDP_CT_REPLIED] = un->timeouts[UDP_CT_REPLIED];
 218
 219         if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) {
 220                 timeouts[UDP_CT_UNREPLIED] =
 221                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ;
 222         }
 223         if (tb[CTA_TIMEOUT_UDP_REPLIED]) {
 224                 timeouts[UDP_CT_REPLIED] =
 225                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ;
 226         }
 227         return 0;
 228 }
 229
 230 static int
 231 udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 232 {
 233         const unsigned int *timeouts = data;
 234
 235         if (nla_put_be32(skb, CTA_TIMEOUT_UDP_UNREPLIED,
 236                          htonl(timeouts[UDP_CT_UNREPLIED] / HZ)) ||
 237             nla_put_be32(skb, CTA_TIMEOUT_UDP_REPLIED,
 238                          htonl(timeouts[UDP_CT_REPLIED] / HZ)))
 239                 goto nla_put_failure;
 240         return 0;
 241
 242 nla_put_failure:
 243         return -ENOSPC;
 244 }
 245
 246 static const struct nla_policy
 247 udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = {
 248        [CTA_TIMEOUT_UDP_UNREPLIED]      = { .type = NLA_U32 },
 249        [CTA_TIMEOUT_UDP_REPLIED]        = { .type = NLA_U32 },
 250 };
 251 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 252
 253 #ifdef CONFIG_SYSCTL
 254 static struct ctl_table udp_sysctl_table[] = {
 255         {
 256                 .procname       = "nf_conntrack_udp_timeout",
 257                 .maxlen         = sizeof(unsigned int),
 258                 .mode           = 0644,
 259                 .proc_handler   = proc_dointvec_jiffies,
 260         },
 261         {
 262                 .procname       = "nf_conntrack_udp_timeout_stream",
 263                 .maxlen         = sizeof(unsigned int),
 264                 .mode           = 0644,
 265                 .proc_handler   = proc_dointvec_jiffies,
 266         },
 267         { }
 268 };
 269 #endif /* CONFIG_SYSCTL */
 270
 271 static int udp_kmemdup_sysctl_table(struct nf_proto_net *pn,
 272                                     struct nf_udp_net *un)
 273 {
 274 #ifdef CONFIG_SYSCTL
 275         if (pn->ctl_table)
 276                 return 0;
 277         pn->ctl_table = kmemdup(udp_sysctl_table,
 278                                 sizeof(udp_sysctl_table),
 279                                 GFP_KERNEL);
 280         if (!pn->ctl_table)
 281                 return -ENOMEM;
 282         pn->ctl_table[0].data = &un->timeouts[UDP_CT_UNREPLIED];
 283         pn->ctl_table[1].data = &un->timeouts[UDP_CT_REPLIED];
 284 #endif
 285         return 0;
 286 }
 287
 288 static int udp_init_net(struct net *net)
 289 {
 290         struct nf_udp_net *un = nf_udp_pernet(net);
 291         struct nf_proto_net *pn = &un->pn;
 292
 293         if (!pn->users) {
 294                 int i;
 295
 296                 for (i = 0; i < UDP_CT_MAX; i++)
 297                         un->timeouts[i] = udp_timeouts[i];
 298         }
 299
 300         return udp_kmemdup_sysctl_table(pn, un);
 301 }
 302
 303 static struct nf_proto_net *udp_get_net_proto(struct net *net)
 304 {
 305         return &net->ct.nf_ct_proto.udp.pn;
 306 }
 307
 308 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udp =
 309 {
 310         .l4proto                = IPPROTO_UDP,
 311         .allow_clash            = true,
 312         .packet                 = udp_packet,
 313 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 314         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 315         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 316         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 317         .nla_policy             = nf_ct_port_nla_policy,
 318 #endif
 319 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 320         .ctnl_timeout           = {
 321                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 322                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 323                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 324                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 325                 .nla_policy     = udp_timeout_nla_policy,
 326         },
 327 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 328         .init_net               = udp_init_net,
 329         .get_net_proto          = udp_get_net_proto,
 330 };
 331
 332 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
 333 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite =
 334 {
 335         .l4proto                = IPPROTO_UDPLITE,
 336         .allow_clash            = true,
 337         .packet                 = udplite_packet,
 338 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 339         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 340         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 341         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 342         .nla_policy             = nf_ct_port_nla_policy,
 343 #endif
 344 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 345         .ctnl_timeout           = {
 346                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 347                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 348                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 349                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 350                 .nla_policy     = udp_timeout_nla_policy,
 351         },
 352 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 353         .init_net               = udp_init_net,
 354         .get_net_proto          = udp_get_net_proto,
 355 };
 356 #endif