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/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
  27 enum udplite_conntrack {
  28         UDPLITE_CT_UNREPLIED,
  29         UDPLITE_CT_REPLIED,
  30         UDPLITE_CT_MAX
  31 };
  32
  33 static unsigned int udplite_timeouts[UDPLITE_CT_MAX] = {
  34         [UDPLITE_CT_UNREPLIED]  = 30*HZ,
  35         [UDPLITE_CT_REPLIED]    = 180*HZ,
  36 };
  37
  38 static bool udplite_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         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_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 int udplite_print_tuple(struct seq_file *s,
  64                                const struct nf_conntrack_tuple *tuple)
  65 {
  66         return seq_printf(s, "sport=%hu dport=%hu ",
  67                           ntohs(tuple->src.u.udp.port),
  68                           ntohs(tuple->dst.u.udp.port));
  69 }
  70
  71 /* Returns verdict for packet, and may modify conntracktype */
  72 static int udplite_packet(struct nf_conn *ct,
  73                           const struct sk_buff *skb,
  74                           unsigned int dataoff,
  75                           enum ip_conntrack_info ctinfo,
  76                           u_int8_t pf,
  77                           unsigned int hooknum)
  78 {
  79         /* If we've seen traffic both ways, this is some kind of UDP
  80            stream.  Extend timeout. */
  81         if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
  82                 nf_ct_refresh_acct(ct, ctinfo, skb,
  83                                    udplite_timeouts[UDPLITE_CT_REPLIED]);
  84                 /* Also, more likely to be important, and not a probe */
  85                 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
  86                         nf_conntrack_event_cache(IPCT_ASSURED, ct);
  87         } else {
  88                 nf_ct_refresh_acct(ct, ctinfo, skb,
  89                                    udplite_timeouts[UDPLITE_CT_UNREPLIED]);
  90         }
  91         return NF_ACCEPT;
  92 }
  93
  94 /* Called when a new connection for this protocol found. */
  95 static bool udplite_new(struct nf_conn *ct, const struct sk_buff *skb,
  96                         unsigned int dataoff)
  97 {
  98         return true;
  99 }
 100
 101 static int udplite_error(struct net *net, struct nf_conn *tmpl,
 102                          struct sk_buff *skb,
 103                          unsigned int dataoff,
 104                          enum ip_conntrack_info *ctinfo,
 105                          u_int8_t pf,
 106                          unsigned int hooknum)
 107 {
 108         unsigned int udplen = skb->len - dataoff;
 109         const struct udphdr *hdr;
 110         struct udphdr _hdr;
 111         unsigned int cscov;
 112
 113         /* Header is too small? */
 114         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 115         if (hdr == NULL) {
 116                 if (LOG_INVALID(net, IPPROTO_UDPLITE))
 117                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 118                                       "nf_ct_udplite: short packet ");
 119                 return -NF_ACCEPT;
 120         }
 121
 122         cscov = ntohs(hdr->len);
 123         if (cscov == 0)
 124                 cscov = udplen;
 125         else if (cscov < sizeof(*hdr) || cscov > udplen) {
 126                 if (LOG_INVALID(net, IPPROTO_UDPLITE))
 127                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 128                                 "nf_ct_udplite: invalid checksum coverage ");
 129                 return -NF_ACCEPT;
 130         }
 131
 132         /* UDPLITE mandates checksums */
 133         if (!hdr->check) {
 134                 if (LOG_INVALID(net, IPPROTO_UDPLITE))
 135                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 136                                       "nf_ct_udplite: checksum missing ");
 137                 return -NF_ACCEPT;
 138         }
 139
 140         /* Checksum invalid? Ignore. */
 141         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 142             nf_checksum_partial(skb, hooknum, dataoff, cscov, IPPROTO_UDP,
 143                                 pf)) {
 144                 if (LOG_INVALID(net, IPPROTO_UDPLITE))
 145                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 146                                       "nf_ct_udplite: bad UDPLite checksum ");
 147                 return -NF_ACCEPT;
 148         }
 149
 150         return NF_ACCEPT;
 151 }
 152
 153 #ifdef CONFIG_SYSCTL
 154 static unsigned int udplite_sysctl_table_users;
 155 static struct ctl_table_header *udplite_sysctl_header;
 156 static struct ctl_table udplite_sysctl_table[] = {
 157         {
 158                 .procname       = "nf_conntrack_udplite_timeout",
 159                 .data           = &udplite_timeouts[UDPLITE_CT_UNREPLIED],
 160                 .maxlen         = sizeof(unsigned int),
 161                 .mode           = 0644,
 162                 .proc_handler   = proc_dointvec_jiffies,
 163         },
 164         {
 165                 .procname       = "nf_conntrack_udplite_timeout_stream",
 166                 .data           = &udplite_timeouts[UDPLITE_CT_REPLIED],
 167                 .maxlen         = sizeof(unsigned int),
 168                 .mode           = 0644,
 169                 .proc_handler   = proc_dointvec_jiffies,
 170         },
 171         { }
 172 };
 173 #endif /* CONFIG_SYSCTL */
 174
 175 static struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite4 __read_mostly =
 176 {
 177         .l3proto                = PF_INET,
 178         .l4proto                = IPPROTO_UDPLITE,
 179         .name                   = "udplite",
 180         .pkt_to_tuple           = udplite_pkt_to_tuple,
 181         .invert_tuple           = udplite_invert_tuple,
 182         .print_tuple            = udplite_print_tuple,
 183         .packet                 = udplite_packet,
 184         .new                    = udplite_new,
 185         .error                  = udplite_error,
 186 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 187         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 188         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 189         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 190         .nla_policy             = nf_ct_port_nla_policy,
 191 #endif
 192 #ifdef CONFIG_SYSCTL
 193         .ctl_table_users        = &udplite_sysctl_table_users,
 194         .ctl_table_header       = &udplite_sysctl_header,
 195         .ctl_table              = udplite_sysctl_table,
 196 #endif
 197 };
 198
 199 static struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite6 __read_mostly =
 200 {
 201         .l3proto                = PF_INET6,
 202         .l4proto                = IPPROTO_UDPLITE,
 203         .name                   = "udplite",
 204         .pkt_to_tuple           = udplite_pkt_to_tuple,
 205         .invert_tuple           = udplite_invert_tuple,
 206         .print_tuple            = udplite_print_tuple,
 207         .packet                 = udplite_packet,
 208         .new                    = udplite_new,
 209         .error                  = udplite_error,
 210 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 211         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 212         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 213         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 214         .nla_policy             = nf_ct_port_nla_policy,
 215 #endif
 216 #ifdef CONFIG_SYSCTL
 217         .ctl_table_users        = &udplite_sysctl_table_users,
 218         .ctl_table_header       = &udplite_sysctl_header,
 219         .ctl_table              = udplite_sysctl_table,
 220 #endif
 221 };
 222
 223 static int __init nf_conntrack_proto_udplite_init(void)
 224 {
 225         int err;
 226
 227         err = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udplite4);
 228         if (err < 0)
 229                 goto err1;
 230         err = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udplite6);
 231         if (err < 0)
 232                 goto err2;
 233         return 0;
 234 err2:
 235         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite4);
 236 err1:
 237         return err;
 238 }
 239
 240 static void __exit nf_conntrack_proto_udplite_exit(void)
 241 {
 242         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite6);
 243         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite4);
 244 }
 245
 246 module_init(nf_conntrack_proto_udplite_init);
 247 module_exit(nf_conntrack_proto_udplite_exit);
 248
 249 MODULE_LICENSE("GPL");