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  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 #include <linux/types.h>
  10 #include <linux/timer.h>
  11 #include <linux/module.h>
  12 #include <linux/udp.h>
  13 #include <linux/seq_file.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/ipv6.h>
  16 #include <net/ip6_checksum.h>
  17 #include <net/checksum.h>
  18
  19 #include <linux/netfilter.h>
  20 #include <linux/netfilter_ipv4.h>
  21 #include <linux/netfilter_ipv6.h>
  22 #include <net/netfilter/nf_conntrack_l4proto.h>
  23 #include <net/netfilter/nf_conntrack_ecache.h>
  24 #include <net/netfilter/nf_log.h>
  25 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
  26 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
  27
  28 static unsigned int udp_timeouts[UDP_CT_MAX] = {
  29         [UDP_CT_UNREPLIED]      = 30*HZ,
  30         [UDP_CT_REPLIED]        = 180*HZ,
  31 };
  32
  33 static inline struct nf_udp_net *udp_pernet(struct net *net)
  34 {
  35         return &net->ct.nf_ct_proto.udp;
  36 }
  37
  38 static bool udp_pkt_to_tuple(const struct sk_buff *skb,
  39                              unsigned int dataoff,
  40                              struct nf_conntrack_tuple *tuple)
  41 {
  42         const struct udphdr *hp;
  43         struct udphdr _hdr;
  44
  45         /* Actually only need first 8 bytes. */
  46         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  47         if (hp == NULL)
  48                 return false;
  49
  50         tuple->src.u.udp.port = hp->source;
  51         tuple->dst.u.udp.port = hp->dest;
  52
  53         return true;
  54 }
  55
  56 static bool udp_invert_tuple(struct nf_conntrack_tuple *tuple,
  57                              const struct nf_conntrack_tuple *orig)
  58 {
  59         tuple->src.u.udp.port = orig->dst.u.udp.port;
  60         tuple->dst.u.udp.port = orig->src.u.udp.port;
  61         return true;
  62 }
  63
  64 /* Print out the per-protocol part of the tuple. */
  65 static int udp_print_tuple(struct seq_file *s,
  66                            const struct nf_conntrack_tuple *tuple)
  67 {
  68         return seq_printf(s, "sport=%hu dport=%hu ",
  69                           ntohs(tuple->src.u.udp.port),
  70                           ntohs(tuple->dst.u.udp.port));
  71 }
  72
  73 static unsigned int *udp_get_timeouts(struct net *net)
  74 {
  75         return udp_pernet(net)->timeouts;
  76 }
  77
  78 /* Returns verdict for packet, and may modify conntracktype */
  79 static int udp_packet(struct nf_conn *ct,
  80                       const struct sk_buff *skb,
  81                       unsigned int dataoff,
  82                       enum ip_conntrack_info ctinfo,
  83                       u_int8_t pf,
  84                       unsigned int hooknum,
  85                       unsigned int *timeouts)
  86 {
  87         /* If we've seen traffic both ways, this is some kind of UDP
  88            stream.  Extend timeout. */
  89         if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
  90                 nf_ct_refresh_acct(ct, ctinfo, skb,
  91                                    timeouts[UDP_CT_REPLIED]);
  92                 /* Also, more likely to be important, and not a probe */
  93                 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
  94                         nf_conntrack_event_cache(IPCT_ASSURED, ct);
  95         } else {
  96                 nf_ct_refresh_acct(ct, ctinfo, skb,
  97                                    timeouts[UDP_CT_UNREPLIED]);
  98         }
  99         return NF_ACCEPT;
 100 }
 101
 102 /* Called when a new connection for this protocol found. */
 103 static bool udp_new(struct nf_conn *ct, const struct sk_buff *skb,
 104                     unsigned int dataoff, unsigned int *timeouts)
 105 {
 106         return true;
 107 }
 108
 109 static int udp_error(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb,
 110                      unsigned int dataoff, enum ip_conntrack_info *ctinfo,
 111                      u_int8_t pf,
 112                      unsigned int hooknum)
 113 {
 114         unsigned int udplen = skb->len - dataoff;
 115         const struct udphdr *hdr;
 116         struct udphdr _hdr;
 117
 118         /* Header is too small? */
 119         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 120         if (hdr == NULL) {
 121                 if (LOG_INVALID(net, IPPROTO_UDP))
 122                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 123                                       "nf_ct_udp: short packet ");
 124                 return -NF_ACCEPT;
 125         }
 126
 127         /* Truncated/malformed packets */
 128         if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
 129                 if (LOG_INVALID(net, IPPROTO_UDP))
 130                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 131                                 "nf_ct_udp: truncated/malformed packet ");
 132                 return -NF_ACCEPT;
 133         }
 134
 135         /* Packet with no checksum */
 136         if (!hdr->check)
 137                 return NF_ACCEPT;
 138
 139         /* Checksum invalid? Ignore.
 140          * We skip checking packets on the outgoing path
 141          * because the checksum is assumed to be correct.
 142          * FIXME: Source route IP option packets --RR */
 143         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 144             nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
 145                 if (LOG_INVALID(net, IPPROTO_UDP))
 146                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 147                                 "nf_ct_udp: bad UDP checksum ");
 148                 return -NF_ACCEPT;
 149         }
 150
 151         return NF_ACCEPT;
 152 }
 153
 154 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 155
 156 #include <linux/netfilter/nfnetlink.h>
 157 #include <linux/netfilter/nfnetlink_cttimeout.h>
 158
 159 static int udp_timeout_nlattr_to_obj(struct nlattr *tb[],
 160                                      struct net *net, void *data)
 161 {
 162         unsigned int *timeouts = data;
 163         struct nf_udp_net *un = udp_pernet(net);
 164
 165         /* set default timeouts for UDP. */
 166         timeouts[UDP_CT_UNREPLIED] = un->timeouts[UDP_CT_UNREPLIED];
 167         timeouts[UDP_CT_REPLIED] = un->timeouts[UDP_CT_REPLIED];
 168
 169         if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) {
 170                 timeouts[UDP_CT_UNREPLIED] =
 171                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ;
 172         }
 173         if (tb[CTA_TIMEOUT_UDP_REPLIED]) {
 174                 timeouts[UDP_CT_REPLIED] =
 175                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ;
 176         }
 177         return 0;
 178 }
 179
 180 static int
 181 udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 182 {
 183         const unsigned int *timeouts = data;
 184
 185         if (nla_put_be32(skb, CTA_TIMEOUT_UDP_UNREPLIED,
 186                          htonl(timeouts[UDP_CT_UNREPLIED] / HZ)) ||
 187             nla_put_be32(skb, CTA_TIMEOUT_UDP_REPLIED,
 188                          htonl(timeouts[UDP_CT_REPLIED] / HZ)))
 189                 goto nla_put_failure;
 190         return 0;
 191
 192 nla_put_failure:
 193         return -ENOSPC;
 194 }
 195
 196 static const struct nla_policy
 197 udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = {
 198        [CTA_TIMEOUT_UDP_UNREPLIED]      = { .type = NLA_U32 },
 199        [CTA_TIMEOUT_UDP_REPLIED]        = { .type = NLA_U32 },
 200 };
 201 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 202
 203 #ifdef CONFIG_SYSCTL
 204 static struct ctl_table udp_sysctl_table[] = {
 205         {
 206                 .procname       = "nf_conntrack_udp_timeout",
 207                 .maxlen         = sizeof(unsigned int),
 208                 .mode           = 0644,
 209                 .proc_handler   = proc_dointvec_jiffies,
 210         },
 211         {
 212                 .procname       = "nf_conntrack_udp_timeout_stream",
 213                 .maxlen         = sizeof(unsigned int),
 214                 .mode           = 0644,
 215                 .proc_handler   = proc_dointvec_jiffies,
 216         },
 217         { }
 218 };
 219 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 220 static struct ctl_table udp_compat_sysctl_table[] = {
 221         {
 222                 .procname       = "ip_conntrack_udp_timeout",
 223                 .maxlen         = sizeof(unsigned int),
 224                 .mode           = 0644,
 225                 .proc_handler   = proc_dointvec_jiffies,
 226         },
 227         {
 228                 .procname       = "ip_conntrack_udp_timeout_stream",
 229                 .maxlen         = sizeof(unsigned int),
 230                 .mode           = 0644,
 231                 .proc_handler   = proc_dointvec_jiffies,
 232         },
 233         { }
 234 };
 235 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 236 #endif /* CONFIG_SYSCTL */
 237
 238 static int udp_kmemdup_sysctl_table(struct nf_proto_net *pn)
 239 {
 240 #ifdef CONFIG_SYSCTL
 241         struct nf_udp_net *un = (struct nf_udp_net *)pn;
 242         if (pn->ctl_table)
 243                 return 0;
 244         pn->ctl_table = kmemdup(udp_sysctl_table,
 245                                 sizeof(udp_sysctl_table),
 246                                 GFP_KERNEL);
 247         if (!pn->ctl_table)
 248                 return -ENOMEM;
 249         pn->ctl_table[0].data = &un->timeouts[UDP_CT_UNREPLIED];
 250         pn->ctl_table[1].data = &un->timeouts[UDP_CT_REPLIED];
 251 #endif
 252         return 0;
 253 }
 254
 255 static int udp_kmemdup_compat_sysctl_table(struct nf_proto_net *pn)
 256 {
 257 #ifdef CONFIG_SYSCTL
 258 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 259         struct nf_udp_net *un = (struct nf_udp_net *)pn;
 260         pn->ctl_compat_table = kmemdup(udp_compat_sysctl_table,
 261                                        sizeof(udp_compat_sysctl_table),
 262                                        GFP_KERNEL);
 263         if (!pn->ctl_compat_table)
 264                 return -ENOMEM;
 265
 266         pn->ctl_compat_table[0].data = &un->timeouts[UDP_CT_UNREPLIED];
 267         pn->ctl_compat_table[1].data = &un->timeouts[UDP_CT_REPLIED];
 268 #endif
 269 #endif
 270         return 0;
 271 }
 272
 273 static void udp_init_net_data(struct nf_udp_net *un)
 274 {
 275         int i;
 276 #ifdef CONFIG_SYSCTL
 277         if (!un->pn.ctl_table) {
 278 #else
 279         if (!un->pn.users++) {
 280 #endif
 281                 for (i = 0; i < UDP_CT_MAX; i++)
 282                         un->timeouts[i] = udp_timeouts[i];
 283         }
 284 }
 285
 286 static int udpv4_init_net(struct net *net, u_int16_t proto)
 287 {
 288         int ret;
 289         struct nf_udp_net *un = udp_pernet(net);
 290         struct nf_proto_net *pn = (struct nf_proto_net *)un;
 291
 292         udp_init_net_data(un);
 293
 294         ret = udp_kmemdup_compat_sysctl_table(pn);
 295         if (ret < 0)
 296                 return ret;
 297
 298         ret = udp_kmemdup_sysctl_table(pn);
 299 #ifdef CONFIG_SYSCTL
 300 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 301         if (ret < 0) {
 302                 kfree(pn->ctl_compat_table);
 303                 pn->ctl_compat_table = NULL;
 304         }
 305 #endif
 306 #endif
 307         return ret;
 308 }
 309
 310 static int udpv6_init_net(struct net *net, u_int16_t proto)
 311 {
 312         struct nf_udp_net *un = udp_pernet(net);
 313         struct nf_proto_net *pn = (struct nf_proto_net *)un;
 314
 315         udp_init_net_data(un);
 316         return udp_kmemdup_sysctl_table(pn);
 317 }
 318
 319 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp4 __read_mostly =
 320 {
 321         .l3proto                = PF_INET,
 322         .l4proto                = IPPROTO_UDP,
 323         .name                   = "udp",
 324         .pkt_to_tuple           = udp_pkt_to_tuple,
 325         .invert_tuple           = udp_invert_tuple,
 326         .print_tuple            = udp_print_tuple,
 327         .packet                 = udp_packet,
 328         .get_timeouts           = udp_get_timeouts,
 329         .new                    = udp_new,
 330         .error                  = udp_error,
 331 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 332         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 333         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 334         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 335         .nla_policy             = nf_ct_port_nla_policy,
 336 #endif
 337 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 338         .ctnl_timeout           = {
 339                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 340                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 341                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 342                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 343                 .nla_policy     = udp_timeout_nla_policy,
 344         },
 345 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 346         .init_net               = udpv4_init_net,
 347 };
 348 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp4);
 349
 350 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp6 __read_mostly =
 351 {
 352         .l3proto                = PF_INET6,
 353         .l4proto                = IPPROTO_UDP,
 354         .name                   = "udp",
 355         .pkt_to_tuple           = udp_pkt_to_tuple,
 356         .invert_tuple           = udp_invert_tuple,
 357         .print_tuple            = udp_print_tuple,
 358         .packet                 = udp_packet,
 359         .get_timeouts           = udp_get_timeouts,
 360         .new                    = udp_new,
 361         .error                  = udp_error,
 362 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 363         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 364         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 365         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 366         .nla_policy             = nf_ct_port_nla_policy,
 367 #endif
 368 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 369         .ctnl_timeout           = {
 370                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 371                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 372                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 373                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 374                 .nla_policy     = udp_timeout_nla_policy,
 375         },
 376 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 377         .init_net               = udpv6_init_net,
 378 };
 379 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp6);