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 nf_conntrack_tuple *tuple)
  42 {
  43         const struct udphdr *hp;
  44         struct udphdr _hdr;
  45
  46         /* Actually only need first 8 bytes. */
  47         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  48         if (hp == NULL)
  49                 return false;
  50
  51         tuple->src.u.udp.port = hp->source;
  52         tuple->dst.u.udp.port = hp->dest;
  53
  54         return true;
  55 }
  56
  57 static bool udp_invert_tuple(struct nf_conntrack_tuple *tuple,
  58                              const struct nf_conntrack_tuple *orig)
  59 {
  60         tuple->src.u.udp.port = orig->dst.u.udp.port;
  61         tuple->dst.u.udp.port = orig->src.u.udp.port;
  62         return true;
  63 }
  64
  65 /* Print out the per-protocol part of the tuple. */
  66 static int udp_print_tuple(struct seq_file *s,
  67                            const struct nf_conntrack_tuple *tuple)
  68 {
  69         return seq_printf(s, "sport=%hu dport=%hu ",
  70                           ntohs(tuple->src.u.udp.port),
  71                           ntohs(tuple->dst.u.udp.port));
  72 }
  73
  74 static unsigned int *udp_get_timeouts(struct net *net)
  75 {
  76         return udp_pernet(net)->timeouts;
  77 }
  78
  79 /* Returns verdict for packet, and may modify conntracktype */
  80 static int udp_packet(struct nf_conn *ct,
  81                       const struct sk_buff *skb,
  82                       unsigned int dataoff,
  83                       enum ip_conntrack_info ctinfo,
  84                       u_int8_t pf,
  85                       unsigned int hooknum,
  86                       unsigned int *timeouts)
  87 {
  88         /* If we've seen traffic both ways, this is some kind of UDP
  89            stream.  Extend timeout. */
  90         if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
  91                 nf_ct_refresh_acct(ct, ctinfo, skb,
  92                                    timeouts[UDP_CT_REPLIED]);
  93                 /* Also, more likely to be important, and not a probe */
  94                 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
  95                         nf_conntrack_event_cache(IPCT_ASSURED, ct);
  96         } else {
  97                 nf_ct_refresh_acct(ct, ctinfo, skb,
  98                                    timeouts[UDP_CT_UNREPLIED]);
  99         }
 100         return NF_ACCEPT;
 101 }
 102
 103 /* Called when a new connection for this protocol found. */
 104 static bool udp_new(struct nf_conn *ct, const struct sk_buff *skb,
 105                     unsigned int dataoff, unsigned int *timeouts)
 106 {
 107         return true;
 108 }
 109
 110 static int udp_error(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb,
 111                      unsigned int dataoff, enum ip_conntrack_info *ctinfo,
 112                      u_int8_t pf,
 113                      unsigned int hooknum)
 114 {
 115         unsigned int udplen = skb->len - dataoff;
 116         const struct udphdr *hdr;
 117         struct udphdr _hdr;
 118
 119         /* Header is too small? */
 120         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 121         if (hdr == NULL) {
 122                 if (LOG_INVALID(net, IPPROTO_UDP))
 123                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 124                                       "nf_ct_udp: short packet ");
 125                 return -NF_ACCEPT;
 126         }
 127
 128         /* Truncated/malformed packets */
 129         if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
 130                 if (LOG_INVALID(net, IPPROTO_UDP))
 131                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 132                                 "nf_ct_udp: truncated/malformed packet ");
 133                 return -NF_ACCEPT;
 134         }
 135
 136         /* Packet with no checksum */
 137         if (!hdr->check)
 138                 return NF_ACCEPT;
 139
 140         /* Checksum invalid? Ignore.
 141          * We skip checking packets on the outgoing path
 142          * because the checksum is assumed to be correct.
 143          * FIXME: Source route IP option packets --RR */
 144         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 145             nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
 146                 if (LOG_INVALID(net, IPPROTO_UDP))
 147                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 148                                 "nf_ct_udp: bad UDP checksum ");
 149                 return -NF_ACCEPT;
 150         }
 151
 152         return NF_ACCEPT;
 153 }
 154
 155 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 156
 157 #include <linux/netfilter/nfnetlink.h>
 158 #include <linux/netfilter/nfnetlink_cttimeout.h>
 159
 160 static int udp_timeout_nlattr_to_obj(struct nlattr *tb[],
 161                                      struct net *net, void *data)
 162 {
 163         unsigned int *timeouts = data;
 164         struct nf_udp_net *un = udp_pernet(net);
 165
 166         /* set default timeouts for UDP. */
 167         timeouts[UDP_CT_UNREPLIED] = un->timeouts[UDP_CT_UNREPLIED];
 168         timeouts[UDP_CT_REPLIED] = un->timeouts[UDP_CT_REPLIED];
 169
 170         if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) {
 171                 timeouts[UDP_CT_UNREPLIED] =
 172                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ;
 173         }
 174         if (tb[CTA_TIMEOUT_UDP_REPLIED]) {
 175                 timeouts[UDP_CT_REPLIED] =
 176                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ;
 177         }
 178         return 0;
 179 }
 180
 181 static int
 182 udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 183 {
 184         const unsigned int *timeouts = data;
 185
 186         if (nla_put_be32(skb, CTA_TIMEOUT_UDP_UNREPLIED,
 187                          htonl(timeouts[UDP_CT_UNREPLIED] / HZ)) ||
 188             nla_put_be32(skb, CTA_TIMEOUT_UDP_REPLIED,
 189                          htonl(timeouts[UDP_CT_REPLIED] / HZ)))
 190                 goto nla_put_failure;
 191         return 0;
 192
 193 nla_put_failure:
 194         return -ENOSPC;
 195 }
 196
 197 static const struct nla_policy
 198 udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = {
 199        [CTA_TIMEOUT_UDP_UNREPLIED]      = { .type = NLA_U32 },
 200        [CTA_TIMEOUT_UDP_REPLIED]        = { .type = NLA_U32 },
 201 };
 202 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 203
 204 #ifdef CONFIG_SYSCTL
 205 static struct ctl_table udp_sysctl_table[] = {
 206         {
 207                 .procname       = "nf_conntrack_udp_timeout",
 208                 .maxlen         = sizeof(unsigned int),
 209                 .mode           = 0644,
 210                 .proc_handler   = proc_dointvec_jiffies,
 211         },
 212         {
 213                 .procname       = "nf_conntrack_udp_timeout_stream",
 214                 .maxlen         = sizeof(unsigned int),
 215                 .mode           = 0644,
 216                 .proc_handler   = proc_dointvec_jiffies,
 217         },
 218         { }
 219 };
 220 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 221 static struct ctl_table udp_compat_sysctl_table[] = {
 222         {
 223                 .procname       = "ip_conntrack_udp_timeout",
 224                 .maxlen         = sizeof(unsigned int),
 225                 .mode           = 0644,
 226                 .proc_handler   = proc_dointvec_jiffies,
 227         },
 228         {
 229                 .procname       = "ip_conntrack_udp_timeout_stream",
 230                 .maxlen         = sizeof(unsigned int),
 231                 .mode           = 0644,
 232                 .proc_handler   = proc_dointvec_jiffies,
 233         },
 234         { }
 235 };
 236 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 237 #endif /* CONFIG_SYSCTL */
 238
 239 static int udp_kmemdup_sysctl_table(struct nf_proto_net *pn,
 240                                     struct nf_udp_net *un)
 241 {
 242 #ifdef CONFIG_SYSCTL
 243         if (pn->ctl_table)
 244                 return 0;
 245         pn->ctl_table = kmemdup(udp_sysctl_table,
 246                                 sizeof(udp_sysctl_table),
 247                                 GFP_KERNEL);
 248         if (!pn->ctl_table)
 249                 return -ENOMEM;
 250         pn->ctl_table[0].data = &un->timeouts[UDP_CT_UNREPLIED];
 251         pn->ctl_table[1].data = &un->timeouts[UDP_CT_REPLIED];
 252 #endif
 253         return 0;
 254 }
 255
 256 static int udp_kmemdup_compat_sysctl_table(struct nf_proto_net *pn,
 257                                            struct nf_udp_net *un)
 258 {
 259 #ifdef CONFIG_SYSCTL
 260 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 261         pn->ctl_compat_table = kmemdup(udp_compat_sysctl_table,
 262                                        sizeof(udp_compat_sysctl_table),
 263                                        GFP_KERNEL);
 264         if (!pn->ctl_compat_table)
 265                 return -ENOMEM;
 266
 267         pn->ctl_compat_table[0].data = &un->timeouts[UDP_CT_UNREPLIED];
 268         pn->ctl_compat_table[1].data = &un->timeouts[UDP_CT_REPLIED];
 269 #endif
 270 #endif
 271         return 0;
 272 }
 273
 274 static int udp_init_net(struct net *net, u_int16_t proto)
 275 {
 276         int ret;
 277         struct nf_udp_net *un = udp_pernet(net);
 278         struct nf_proto_net *pn = &un->pn;
 279
 280         if (!pn->users) {
 281                 int i;
 282
 283                 for (i = 0; i < UDP_CT_MAX; i++)
 284                         un->timeouts[i] = udp_timeouts[i];
 285         }
 286
 287         if (proto == AF_INET) {
 288                 ret = udp_kmemdup_compat_sysctl_table(pn, un);
 289                 if (ret < 0)
 290                         return ret;
 291
 292                 ret = udp_kmemdup_sysctl_table(pn, un);
 293                 if (ret < 0)
 294                         nf_ct_kfree_compat_sysctl_table(pn);
 295         } else
 296                 ret = udp_kmemdup_sysctl_table(pn, un);
 297
 298         return ret;
 299 }
 300
 301 static struct nf_proto_net *udp_get_net_proto(struct net *net)
 302 {
 303         return &net->ct.nf_ct_proto.udp.pn;
 304 }
 305
 306 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp4 __read_mostly =
 307 {
 308         .l3proto                = PF_INET,
 309         .l4proto                = IPPROTO_UDP,
 310         .name                   = "udp",
 311         .pkt_to_tuple           = udp_pkt_to_tuple,
 312         .invert_tuple           = udp_invert_tuple,
 313         .print_tuple            = udp_print_tuple,
 314         .packet                 = udp_packet,
 315         .get_timeouts           = udp_get_timeouts,
 316         .new                    = udp_new,
 317         .error                  = udp_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 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_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_CT_NETLINK_TIMEOUT */
 333         .init_net               = udp_init_net,
 334         .get_net_proto          = udp_get_net_proto,
 335 };
 336 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp4);
 337
 338 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp6 __read_mostly =
 339 {
 340         .l3proto                = PF_INET6,
 341         .l4proto                = IPPROTO_UDP,
 342         .name                   = "udp",
 343         .pkt_to_tuple           = udp_pkt_to_tuple,
 344         .invert_tuple           = udp_invert_tuple,
 345         .print_tuple            = udp_print_tuple,
 346         .packet                 = udp_packet,
 347         .get_timeouts           = udp_get_timeouts,
 348         .new                    = udp_new,
 349         .error                  = udp_error,
 350 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 351         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 352         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 353         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 354         .nla_policy             = nf_ct_port_nla_policy,
 355 #endif
 356 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 357         .ctnl_timeout           = {
 358                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 359                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 360                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 361                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 362                 .nla_policy     = udp_timeout_nla_policy,
 363         },
 364 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 365         .init_net               = udp_init_net,
 366         .get_net_proto          = udp_get_net_proto,
 367 };
 368 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp6);