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 static int udp_error(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb,
 112                      unsigned int dataoff, enum ip_conntrack_info *ctinfo,
 113                      u_int8_t pf,
 114                      unsigned int hooknum)
 115 {
 116         unsigned int udplen = skb->len - dataoff;
 117         const struct udphdr *hdr;
 118         struct udphdr _hdr;
 119
 120         /* Header is too small? */
 121         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 122         if (hdr == NULL) {
 123                 if (LOG_INVALID(net, IPPROTO_UDP))
 124                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 125                                       "nf_ct_udp: short packet ");
 126                 return -NF_ACCEPT;
 127         }
 128
 129         /* Truncated/malformed packets */
 130         if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
 131                 if (LOG_INVALID(net, IPPROTO_UDP))
 132                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 133                                 "nf_ct_udp: truncated/malformed packet ");
 134                 return -NF_ACCEPT;
 135         }
 136
 137         /* Packet with no checksum */
 138         if (!hdr->check)
 139                 return NF_ACCEPT;
 140
 141         /* Checksum invalid? Ignore.
 142          * We skip checking packets on the outgoing path
 143          * because the checksum is assumed to be correct.
 144          * FIXME: Source route IP option packets --RR */
 145         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 146             nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
 147                 if (LOG_INVALID(net, IPPROTO_UDP))
 148                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 149                                 "nf_ct_udp: bad UDP checksum ");
 150                 return -NF_ACCEPT;
 151         }
 152
 153         return NF_ACCEPT;
 154 }
 155
 156 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 157
 158 #include <linux/netfilter/nfnetlink.h>
 159 #include <linux/netfilter/nfnetlink_cttimeout.h>
 160
 161 static int udp_timeout_nlattr_to_obj(struct nlattr *tb[],
 162                                      struct net *net, void *data)
 163 {
 164         unsigned int *timeouts = data;
 165         struct nf_udp_net *un = udp_pernet(net);
 166
 167         /* set default timeouts for UDP. */
 168         timeouts[UDP_CT_UNREPLIED] = un->timeouts[UDP_CT_UNREPLIED];
 169         timeouts[UDP_CT_REPLIED] = un->timeouts[UDP_CT_REPLIED];
 170
 171         if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) {
 172                 timeouts[UDP_CT_UNREPLIED] =
 173                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ;
 174         }
 175         if (tb[CTA_TIMEOUT_UDP_REPLIED]) {
 176                 timeouts[UDP_CT_REPLIED] =
 177                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ;
 178         }
 179         return 0;
 180 }
 181
 182 static int
 183 udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 184 {
 185         const unsigned int *timeouts = data;
 186
 187         if (nla_put_be32(skb, CTA_TIMEOUT_UDP_UNREPLIED,
 188                          htonl(timeouts[UDP_CT_UNREPLIED] / HZ)) ||
 189             nla_put_be32(skb, CTA_TIMEOUT_UDP_REPLIED,
 190                          htonl(timeouts[UDP_CT_REPLIED] / HZ)))
 191                 goto nla_put_failure;
 192         return 0;
 193
 194 nla_put_failure:
 195         return -ENOSPC;
 196 }
 197
 198 static const struct nla_policy
 199 udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = {
 200        [CTA_TIMEOUT_UDP_UNREPLIED]      = { .type = NLA_U32 },
 201        [CTA_TIMEOUT_UDP_REPLIED]        = { .type = NLA_U32 },
 202 };
 203 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 204
 205 #ifdef CONFIG_SYSCTL
 206 static struct ctl_table udp_sysctl_table[] = {
 207         {
 208                 .procname       = "nf_conntrack_udp_timeout",
 209                 .maxlen         = sizeof(unsigned int),
 210                 .mode           = 0644,
 211                 .proc_handler   = proc_dointvec_jiffies,
 212         },
 213         {
 214                 .procname       = "nf_conntrack_udp_timeout_stream",
 215                 .maxlen         = sizeof(unsigned int),
 216                 .mode           = 0644,
 217                 .proc_handler   = proc_dointvec_jiffies,
 218         },
 219         { }
 220 };
 221 #endif /* CONFIG_SYSCTL */
 222
 223 static int udp_kmemdup_sysctl_table(struct nf_proto_net *pn,
 224                                     struct nf_udp_net *un)
 225 {
 226 #ifdef CONFIG_SYSCTL
 227         if (pn->ctl_table)
 228                 return 0;
 229         pn->ctl_table = kmemdup(udp_sysctl_table,
 230                                 sizeof(udp_sysctl_table),
 231                                 GFP_KERNEL);
 232         if (!pn->ctl_table)
 233                 return -ENOMEM;
 234         pn->ctl_table[0].data = &un->timeouts[UDP_CT_UNREPLIED];
 235         pn->ctl_table[1].data = &un->timeouts[UDP_CT_REPLIED];
 236 #endif
 237         return 0;
 238 }
 239
 240 static int udp_init_net(struct net *net, u_int16_t proto)
 241 {
 242         struct nf_udp_net *un = udp_pernet(net);
 243         struct nf_proto_net *pn = &un->pn;
 244
 245         if (!pn->users) {
 246                 int i;
 247
 248                 for (i = 0; i < UDP_CT_MAX; i++)
 249                         un->timeouts[i] = udp_timeouts[i];
 250         }
 251
 252         return udp_kmemdup_sysctl_table(pn, un);
 253 }
 254
 255 static struct nf_proto_net *udp_get_net_proto(struct net *net)
 256 {
 257         return &net->ct.nf_ct_proto.udp.pn;
 258 }
 259
 260 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp4 __read_mostly =
 261 {
 262         .l3proto                = PF_INET,
 263         .l4proto                = IPPROTO_UDP,
 264         .name                   = "udp",
 265         .allow_clash            = true,
 266         .pkt_to_tuple           = udp_pkt_to_tuple,
 267         .invert_tuple           = udp_invert_tuple,
 268         .print_tuple            = udp_print_tuple,
 269         .packet                 = udp_packet,
 270         .get_timeouts           = udp_get_timeouts,
 271         .new                    = udp_new,
 272         .error                  = udp_error,
 273 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 274         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 275         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 276         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 277         .nla_policy             = nf_ct_port_nla_policy,
 278 #endif
 279 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 280         .ctnl_timeout           = {
 281                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 282                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 283                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 284                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 285                 .nla_policy     = udp_timeout_nla_policy,
 286         },
 287 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 288         .init_net               = udp_init_net,
 289         .get_net_proto          = udp_get_net_proto,
 290 };
 291 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp4);
 292
 293 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp6 __read_mostly =
 294 {
 295         .l3proto                = PF_INET6,
 296         .l4proto                = IPPROTO_UDP,
 297         .name                   = "udp",
 298         .allow_clash            = true,
 299         .pkt_to_tuple           = udp_pkt_to_tuple,
 300         .invert_tuple           = udp_invert_tuple,
 301         .print_tuple            = udp_print_tuple,
 302         .packet                 = udp_packet,
 303         .get_timeouts           = udp_get_timeouts,
 304         .new                    = udp_new,
 305         .error                  = udp_error,
 306 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 307         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 308         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 309         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 310         .nla_policy             = nf_ct_port_nla_policy,
 311 #endif
 312 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 313         .ctnl_timeout           = {
 314                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 315                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 316                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 317                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 318                 .nla_policy     = udp_timeout_nla_policy,
 319         },
 320 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 321         .init_net               = udp_init_net,
 322         .get_net_proto          = udp_get_net_proto,
 323 };
 324 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp6);