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 static unsigned int nf_ct_udplite_timeout __read_mostly = 30*HZ;
  28 static unsigned int nf_ct_udplite_timeout_stream __read_mostly = 180*HZ;
  29
  30 static int udplite_pkt_to_tuple(const struct sk_buff *skb,
  31                                 unsigned int dataoff,
  32                                 struct nf_conntrack_tuple *tuple)
  33 {
  34         const struct udphdr *hp;
  35         struct udphdr _hdr;
  36
  37         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  38         if (hp == NULL)
  39                 return 0;
  40
  41         tuple->src.u.udp.port = hp->source;
  42         tuple->dst.u.udp.port = hp->dest;
  43         return 1;
  44 }
  45
  46 static int udplite_invert_tuple(struct nf_conntrack_tuple *tuple,
  47                                 const struct nf_conntrack_tuple *orig)
  48 {
  49         tuple->src.u.udp.port = orig->dst.u.udp.port;
  50         tuple->dst.u.udp.port = orig->src.u.udp.port;
  51         return 1;
  52 }
  53
  54 /* Print out the per-protocol part of the tuple. */
  55 static int udplite_print_tuple(struct seq_file *s,
  56                                const struct nf_conntrack_tuple *tuple)
  57 {
  58         return seq_printf(s, "sport=%hu dport=%hu ",
  59                           ntohs(tuple->src.u.udp.port),
  60                           ntohs(tuple->dst.u.udp.port));
  61 }
  62
  63 /* Returns verdict for packet, and may modify conntracktype */
  64 static int udplite_packet(struct nf_conn *ct,
  65                           const struct sk_buff *skb,
  66                           unsigned int dataoff,
  67                           enum ip_conntrack_info ctinfo,
  68                           int pf,
  69                           unsigned int hooknum)
  70 {
  71         /* If we've seen traffic both ways, this is some kind of UDP
  72            stream.  Extend timeout. */
  73         if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
  74                 nf_ct_refresh_acct(ct, ctinfo, skb,
  75                                    nf_ct_udplite_timeout_stream);
  76                 /* Also, more likely to be important, and not a probe */
  77                 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
  78                         nf_conntrack_event_cache(IPCT_STATUS, skb);
  79         } else
  80                 nf_ct_refresh_acct(ct, ctinfo, skb, nf_ct_udplite_timeout);
  81
  82         return NF_ACCEPT;
  83 }
  84
  85 /* Called when a new connection for this protocol found. */
  86 static int udplite_new(struct nf_conn *ct, const struct sk_buff *skb,
  87                        unsigned int dataoff)
  88 {
  89         return 1;
  90 }
  91
  92 static int udplite_error(struct sk_buff *skb, unsigned int dataoff,
  93                          enum ip_conntrack_info *ctinfo,
  94                          int pf,
  95                          unsigned int hooknum)
  96 {
  97         unsigned int udplen = skb->len - dataoff;
  98         const struct udphdr *hdr;
  99         struct udphdr _hdr;
 100         unsigned int cscov;
 101
 102         /* Header is too small? */
 103         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 104         if (hdr == NULL) {
 105                 if (LOG_INVALID(IPPROTO_UDPLITE))
 106                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 107                                       "nf_ct_udplite: short packet ");
 108                 return -NF_ACCEPT;
 109         }
 110
 111         cscov = ntohs(hdr->len);
 112         if (cscov == 0)
 113                 cscov = udplen;
 114         else if (cscov < sizeof(*hdr) || cscov > udplen) {
 115                 if (LOG_INVALID(IPPROTO_UDPLITE))
 116                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 117                                 "nf_ct_udplite: invalid checksum coverage ");
 118                 return -NF_ACCEPT;
 119         }
 120
 121         /* UDPLITE mandates checksums */
 122         if (!hdr->check) {
 123                 if (LOG_INVALID(IPPROTO_UDPLITE))
 124                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 125                                       "nf_ct_udplite: checksum missing ");
 126                 return -NF_ACCEPT;
 127         }
 128
 129         /* Checksum invalid? Ignore. */
 130         if (nf_conntrack_checksum && !skb_csum_unnecessary(skb) &&
 131             hooknum == NF_INET_PRE_ROUTING) {
 132                 if (pf == PF_INET) {
 133                         struct iphdr *iph = ip_hdr(skb);
 134
 135                         skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
 136                                                        udplen, IPPROTO_UDPLITE, 0);
 137                 } else {
 138                         struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 139                         __wsum hsum = skb_checksum(skb, 0, dataoff, 0);
 140
 141                         skb->csum = ~csum_unfold(
 142                                 csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
 143                                                 udplen, IPPROTO_UDPLITE,
 144                                                 csum_sub(0, hsum)));
 145                 }
 146
 147                 skb->ip_summed = CHECKSUM_NONE;
 148                 if (__skb_checksum_complete_head(skb, dataoff + cscov)) {
 149                         if (LOG_INVALID(IPPROTO_UDPLITE))
 150                                 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 151                                               "nf_ct_udplite: bad UDPLite "
 152                                               "checksum ");
 153                         return -NF_ACCEPT;
 154                 }
 155                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 156         }
 157
 158         return NF_ACCEPT;
 159 }
 160
 161 #ifdef CONFIG_SYSCTL
 162 static unsigned int udplite_sysctl_table_users;
 163 static struct ctl_table_header *udplite_sysctl_header;
 164 static struct ctl_table udplite_sysctl_table[] = {
 165         {
 166                 .ctl_name       = CTL_UNNUMBERED,
 167                 .procname       = "nf_conntrack_udplite_timeout",
 168                 .data           = &nf_ct_udplite_timeout,
 169                 .maxlen         = sizeof(unsigned int),
 170                 .mode           = 0644,
 171                 .proc_handler   = &proc_dointvec_jiffies,
 172         },
 173         {
 174                 .ctl_name       = CTL_UNNUMBERED,
 175                 .procname       = "nf_conntrack_udplite_timeout_stream",
 176                 .data           = &nf_ct_udplite_timeout_stream,
 177                 .maxlen         = sizeof(unsigned int),
 178                 .mode           = 0644,
 179                 .proc_handler   = &proc_dointvec_jiffies,
 180         },
 181         {
 182                 .ctl_name       = 0
 183         }
 184 };
 185 #endif /* CONFIG_SYSCTL */
 186
 187 static struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite4 __read_mostly =
 188 {
 189         .l3proto                = PF_INET,
 190         .l4proto                = IPPROTO_UDPLITE,
 191         .name                   = "udplite",
 192         .pkt_to_tuple           = udplite_pkt_to_tuple,
 193         .invert_tuple           = udplite_invert_tuple,
 194         .print_tuple            = udplite_print_tuple,
 195         .packet                 = udplite_packet,
 196         .new                    = udplite_new,
 197         .error                  = udplite_error,
 198 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 199         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 200         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 201         .nla_policy             = nf_ct_port_nla_policy,
 202 #endif
 203 #ifdef CONFIG_SYSCTL
 204         .ctl_table_users        = &udplite_sysctl_table_users,
 205         .ctl_table_header       = &udplite_sysctl_header,
 206         .ctl_table              = udplite_sysctl_table,
 207 #endif
 208 };
 209
 210 static struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite6 __read_mostly =
 211 {
 212         .l3proto                = PF_INET6,
 213         .l4proto                = IPPROTO_UDPLITE,
 214         .name                   = "udplite",
 215         .pkt_to_tuple           = udplite_pkt_to_tuple,
 216         .invert_tuple           = udplite_invert_tuple,
 217         .print_tuple            = udplite_print_tuple,
 218         .packet                 = udplite_packet,
 219         .new                    = udplite_new,
 220         .error                  = udplite_error,
 221 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 222         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 223         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 224         .nla_policy             = nf_ct_port_nla_policy,
 225 #endif
 226 #ifdef CONFIG_SYSCTL
 227         .ctl_table_users        = &udplite_sysctl_table_users,
 228         .ctl_table_header       = &udplite_sysctl_header,
 229         .ctl_table              = udplite_sysctl_table,
 230 #endif
 231 };
 232
 233 static int __init nf_conntrack_proto_udplite_init(void)
 234 {
 235         int err;
 236
 237         err = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udplite4);
 238         if (err < 0)
 239                 goto err1;
 240         err = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udplite6);
 241         if (err < 0)
 242                 goto err2;
 243         return 0;
 244 err2:
 245         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite4);
 246 err1:
 247         return err;
 248 }
 249
 250 static void __exit nf_conntrack_proto_udplite_exit(void)
 251 {
 252         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite6);
 253         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite4);
 254 }
 255
 256 module_init(nf_conntrack_proto_udplite_init);
 257 module_exit(nf_conntrack_proto_udplite_exit);
 258
 259 MODULE_LICENSE("GPL");