net/netfilter/nf_conntrack_proto_udplite.c

   1 /* (C) 1999-2001 Paul `Rusty' Russell
   2  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   3  * (C) 2007 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/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
  26 static unsigned int udplite_timeouts[UDPLITE_CT_MAX] = {
  27         [UDPLITE_CT_UNREPLIED]  = 30*HZ,
  28         [UDPLITE_CT_REPLIED]    = 180*HZ,
  29 };
  30
  31 static inline struct nf_udplite_net *udplite_pernet(struct net *net)
  32 {
  33         return &net->ct.nf_ct_proto.udplite;
  34 }
  35
  36 static bool udplite_pkt_to_tuple(const struct sk_buff *skb,
  37                                  unsigned int dataoff,
  38                                  struct net *net,
  39                                  struct nf_conntrack_tuple *tuple)
  40 {
  41         const struct udphdr *hp;
  42         struct udphdr _hdr;
  43
  44         /* Actually only need first 4 bytes to get ports. */
  45         hp = skb_header_pointer(skb, dataoff, 4, &_hdr);
  46         if (hp == NULL)
  47                 return false;
  48
  49         tuple->src.u.udp.port = hp->source;
  50         tuple->dst.u.udp.port = hp->dest;
  51         return true;
  52 }
  53
  54 static bool udplite_invert_tuple(struct nf_conntrack_tuple *tuple,
  55                                  const struct nf_conntrack_tuple *orig)
  56 {
  57         tuple->src.u.udp.port = orig->dst.u.udp.port;
  58         tuple->dst.u.udp.port = orig->src.u.udp.port;
  59         return true;
  60 }
  61
  62 /* Print out the per-protocol part of the tuple. */
  63 static void udplite_print_tuple(struct seq_file *s,
  64                                 const struct nf_conntrack_tuple *tuple)
  65 {
  66         seq_printf(s, "sport=%hu dport=%hu ",
  67                    ntohs(tuple->src.u.udp.port),
  68                    ntohs(tuple->dst.u.udp.port));
  69 }
  70
  71 static unsigned int *udplite_get_timeouts(struct net *net)
  72 {
  73         return udplite_pernet(net)->timeouts;
  74 }
  75
  76 /* Returns verdict for packet, and may modify conntracktype */
  77 static int udplite_packet(struct nf_conn *ct,
  78                           const struct sk_buff *skb,
  79                           unsigned int dataoff,
  80                           enum ip_conntrack_info ctinfo,
  81                           u_int8_t pf,
  82                           unsigned int hooknum,
  83                           unsigned int *timeouts)
  84 {
  85         /* If we've seen traffic both ways, this is some kind of UDP
  86            stream.  Extend timeout. */
  87         if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
  88                 nf_ct_refresh_acct(ct, ctinfo, skb,
  89                                    timeouts[UDPLITE_CT_REPLIED]);
  90                 /* Also, more likely to be important, and not a probe */
  91                 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
  92                         nf_conntrack_event_cache(IPCT_ASSURED, ct);
  93         } else {
  94                 nf_ct_refresh_acct(ct, ctinfo, skb,
  95                                    timeouts[UDPLITE_CT_UNREPLIED]);
  96         }
  97         return NF_ACCEPT;
  98 }
  99
 100 /* Called when a new connection for this protocol found. */
 101 static bool udplite_new(struct nf_conn *ct, const struct sk_buff *skb,
 102                         unsigned int dataoff, unsigned int *timeouts)
 103 {
 104         return true;
 105 }
 106
 107 static int udplite_error(struct net *net, struct nf_conn *tmpl,
 108                          struct sk_buff *skb,
 109                          unsigned int dataoff,
 110                          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         unsigned int cscov;
 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_UDPLITE))
 123                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 124                                       "nf_ct_udplite: short packet ");
 125                 return -NF_ACCEPT;
 126         }
 127
 128         cscov = ntohs(hdr->len);
 129         if (cscov == 0)
 130                 cscov = udplen;
 131         else if (cscov < sizeof(*hdr) || cscov > udplen) {
 132                 if (LOG_INVALID(net, IPPROTO_UDPLITE))
 133                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 134                                 "nf_ct_udplite: invalid checksum coverage ");
 135                 return -NF_ACCEPT;
 136         }
 137
 138         /* UDPLITE mandates checksums */
 139         if (!hdr->check) {
 140                 if (LOG_INVALID(net, IPPROTO_UDPLITE))
 141                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 142                                       "nf_ct_udplite: checksum missing ");
 143                 return -NF_ACCEPT;
 144         }
 145
 146         /* Checksum invalid? Ignore. */
 147         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 148             nf_checksum_partial(skb, hooknum, dataoff, cscov, IPPROTO_UDP,
 149                                 pf)) {
 150                 if (LOG_INVALID(net, IPPROTO_UDPLITE))
 151                         nf_log_packet(net, pf, 0, skb, NULL, NULL, NULL,
 152                                       "nf_ct_udplite: bad UDPLite checksum ");
 153                 return -NF_ACCEPT;
 154         }
 155
 156         return NF_ACCEPT;
 157 }
 158
 159 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 160
 161 #include <linux/netfilter/nfnetlink.h>
 162 #include <linux/netfilter/nfnetlink_cttimeout.h>
 163
 164 static int udplite_timeout_nlattr_to_obj(struct nlattr *tb[],
 165                                          struct net *net, void *data)
 166 {
 167         unsigned int *timeouts = data;
 168         struct nf_udplite_net *un = udplite_pernet(net);
 169
 170         /* set default timeouts for UDPlite. */
 171         timeouts[UDPLITE_CT_UNREPLIED] = un->timeouts[UDPLITE_CT_UNREPLIED];
 172         timeouts[UDPLITE_CT_REPLIED] = un->timeouts[UDPLITE_CT_REPLIED];
 173
 174         if (tb[CTA_TIMEOUT_UDPLITE_UNREPLIED]) {
 175                 timeouts[UDPLITE_CT_UNREPLIED] =
 176                   ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDPLITE_UNREPLIED])) * HZ;
 177         }
 178         if (tb[CTA_TIMEOUT_UDPLITE_REPLIED]) {
 179                 timeouts[UDPLITE_CT_REPLIED] =
 180                   ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDPLITE_REPLIED])) * HZ;
 181         }
 182         return 0;
 183 }
 184
 185 static int
 186 udplite_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 187 {
 188         const unsigned int *timeouts = data;
 189
 190         if (nla_put_be32(skb, CTA_TIMEOUT_UDPLITE_UNREPLIED,
 191                          htonl(timeouts[UDPLITE_CT_UNREPLIED] / HZ)) ||
 192             nla_put_be32(skb, CTA_TIMEOUT_UDPLITE_REPLIED,
 193                          htonl(timeouts[UDPLITE_CT_REPLIED] / HZ)))
 194                 goto nla_put_failure;
 195         return 0;
 196
 197 nla_put_failure:
 198         return -ENOSPC;
 199 }
 200
 201 static const struct nla_policy
 202 udplite_timeout_nla_policy[CTA_TIMEOUT_UDPLITE_MAX+1] = {
 203         [CTA_TIMEOUT_UDPLITE_UNREPLIED] = { .type = NLA_U32 },
 204         [CTA_TIMEOUT_UDPLITE_REPLIED]   = { .type = NLA_U32 },
 205 };
 206 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 207
 208 #ifdef CONFIG_SYSCTL
 209 static struct ctl_table udplite_sysctl_table[] = {
 210         {
 211                 .procname       = "nf_conntrack_udplite_timeout",
 212                 .maxlen         = sizeof(unsigned int),
 213                 .mode           = 0644,
 214                 .proc_handler   = proc_dointvec_jiffies,
 215         },
 216         {
 217                 .procname       = "nf_conntrack_udplite_timeout_stream",
 218                 .maxlen         = sizeof(unsigned int),
 219                 .mode           = 0644,
 220                 .proc_handler   = proc_dointvec_jiffies,
 221         },
 222         { }
 223 };
 224 #endif /* CONFIG_SYSCTL */
 225
 226 static int udplite_kmemdup_sysctl_table(struct nf_proto_net *pn,
 227                                         struct nf_udplite_net *un)
 228 {
 229 #ifdef CONFIG_SYSCTL
 230         if (pn->ctl_table)
 231                 return 0;
 232
 233         pn->ctl_table = kmemdup(udplite_sysctl_table,
 234                                 sizeof(udplite_sysctl_table),
 235                                 GFP_KERNEL);
 236         if (!pn->ctl_table)
 237                 return -ENOMEM;
 238
 239         pn->ctl_table[0].data = &un->timeouts[UDPLITE_CT_UNREPLIED];
 240         pn->ctl_table[1].data = &un->timeouts[UDPLITE_CT_REPLIED];
 241 #endif
 242         return 0;
 243 }
 244
 245 static int udplite_init_net(struct net *net, u_int16_t proto)
 246 {
 247         struct nf_udplite_net *un = udplite_pernet(net);
 248         struct nf_proto_net *pn = &un->pn;
 249
 250         if (!pn->users) {
 251                 int i;
 252
 253                 for (i = 0 ; i < UDPLITE_CT_MAX; i++)
 254                         un->timeouts[i] = udplite_timeouts[i];
 255         }
 256
 257         return udplite_kmemdup_sysctl_table(pn, un);
 258 }
 259
 260 struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite4 __read_mostly =
 261 {
 262         .l3proto                = PF_INET,
 263         .l4proto                = IPPROTO_UDPLITE,
 264         .name                   = "udplite",
 265         .allow_clash            = true,
 266         .pkt_to_tuple           = udplite_pkt_to_tuple,
 267         .invert_tuple           = udplite_invert_tuple,
 268         .print_tuple            = udplite_print_tuple,
 269         .packet                 = udplite_packet,
 270         .get_timeouts           = udplite_get_timeouts,
 271         .new                    = udplite_new,
 272         .error                  = udplite_error,
 273 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 274         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 275         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 276         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 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  = udplite_timeout_nlattr_to_obj,
 282                 .obj_to_nlattr  = udplite_timeout_obj_to_nlattr,
 283                 .nlattr_max     = CTA_TIMEOUT_UDPLITE_MAX,
 284                 .obj_size       = sizeof(unsigned int) *
 285                                         CTA_TIMEOUT_UDPLITE_MAX,
 286                 .nla_policy     = udplite_timeout_nla_policy,
 287         },
 288 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 289         .init_net               = udplite_init_net,
 290 };
 291 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udplite4);
 292
 293 struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite6 __read_mostly =
 294 {
 295         .l3proto                = PF_INET6,
 296         .l4proto                = IPPROTO_UDPLITE,
 297         .name                   = "udplite",
 298         .allow_clash            = true,
 299         .pkt_to_tuple           = udplite_pkt_to_tuple,
 300         .invert_tuple           = udplite_invert_tuple,
 301         .print_tuple            = udplite_print_tuple,
 302         .packet                 = udplite_packet,
 303         .get_timeouts           = udplite_get_timeouts,
 304         .new                    = udplite_new,
 305         .error                  = udplite_error,
 306 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 307         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 308         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 309         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 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  = udplite_timeout_nlattr_to_obj,
 315                 .obj_to_nlattr  = udplite_timeout_obj_to_nlattr,
 316                 .nlattr_max     = CTA_TIMEOUT_UDPLITE_MAX,
 317                 .obj_size       = sizeof(unsigned int) *
 318                                         CTA_TIMEOUT_UDPLITE_MAX,
 319                 .nla_policy     = udplite_timeout_nla_policy,
 320         },
 321 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 322         .init_net               = udplite_init_net,
 323 };
 324 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udplite6);