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
  26 static unsigned int nf_ct_udplite_timeout __read_mostly = 30*HZ;
  27 static unsigned int nf_ct_udplite_timeout_stream __read_mostly = 180*HZ;
  28
  29 static int udplite_pkt_to_tuple(const struct sk_buff *skb,
  30                                 unsigned int dataoff,
  31                                 struct nf_conntrack_tuple *tuple)
  32 {
  33         struct udphdr _hdr, *hp;
  34
  35         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  36         if (hp == NULL)
  37                 return 0;
  38
  39         tuple->src.u.udp.port = hp->source;
  40         tuple->dst.u.udp.port = hp->dest;
  41         return 1;
  42 }
  43
  44 static int udplite_invert_tuple(struct nf_conntrack_tuple *tuple,
  45                                 const struct nf_conntrack_tuple *orig)
  46 {
  47         tuple->src.u.udp.port = orig->dst.u.udp.port;
  48         tuple->dst.u.udp.port = orig->src.u.udp.port;
  49         return 1;
  50 }
  51
  52 /* Print out the per-protocol part of the tuple. */
  53 static int udplite_print_tuple(struct seq_file *s,
  54                                const struct nf_conntrack_tuple *tuple)
  55 {
  56         return seq_printf(s, "sport=%hu dport=%hu ",
  57                           ntohs(tuple->src.u.udp.port),
  58                           ntohs(tuple->dst.u.udp.port));
  59 }
  60
  61 /* Print out the private part of the conntrack. */
  62 static int udplite_print_conntrack(struct seq_file *s,
  63                                    const struct nf_conn *conntrack)
  64 {
  65         return 0;
  66 }
  67
  68 /* Returns verdict for packet, and may modify conntracktype */
  69 static int udplite_packet(struct nf_conn *conntrack,
  70                           const struct sk_buff *skb,
  71                           unsigned int dataoff,
  72                           enum ip_conntrack_info ctinfo,
  73                           int pf,
  74                           unsigned int hooknum)
  75 {
  76         /* If we've seen traffic both ways, this is some kind of UDP
  77            stream.  Extend timeout. */
  78         if (test_bit(IPS_SEEN_REPLY_BIT, &conntrack->status)) {
  79                 nf_ct_refresh_acct(conntrack, ctinfo, skb,
  80                                    nf_ct_udplite_timeout_stream);
  81                 /* Also, more likely to be important, and not a probe */
  82                 if (!test_and_set_bit(IPS_ASSURED_BIT, &conntrack->status))
  83                         nf_conntrack_event_cache(IPCT_STATUS, skb);
  84         } else
  85                 nf_ct_refresh_acct(conntrack, ctinfo, skb,
  86                                    nf_ct_udplite_timeout);
  87
  88         return NF_ACCEPT;
  89 }
  90
  91 /* Called when a new connection for this protocol found. */
  92 static int udplite_new(struct nf_conn *conntrack, const struct sk_buff *skb,
  93                        unsigned int dataoff)
  94 {
  95         return 1;
  96 }
  97
  98 static int udplite_error(struct sk_buff *skb, unsigned int dataoff,
  99                          enum ip_conntrack_info *ctinfo,
 100                          int pf,
 101                          unsigned int hooknum)
 102 {
 103         unsigned int udplen = skb->len - dataoff;
 104         struct udphdr _hdr, *hdr;
 105         unsigned int cscov;
 106
 107         /* Header is too small? */
 108         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 109         if (hdr == NULL) {
 110                 if (LOG_INVALID(IPPROTO_UDPLITE))
 111                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 112                                       "nf_ct_udplite: short packet ");
 113                 return -NF_ACCEPT;
 114         }
 115
 116         cscov = ntohs(hdr->len);
 117         if (cscov == 0)
 118                 cscov = udplen;
 119         else if (cscov < sizeof(*hdr) || cscov > udplen) {
 120                 if (LOG_INVALID(IPPROTO_UDPLITE))
 121                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 122                                 "nf_ct_udplite: invalid checksum coverage ");
 123                 return -NF_ACCEPT;
 124         }
 125
 126         /* UDPLITE mandates checksums */
 127         if (!hdr->check) {
 128                 if (LOG_INVALID(IPPROTO_UDPLITE))
 129                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 130                                       "nf_ct_udplite: checksum missing ");
 131                 return -NF_ACCEPT;
 132         }
 133
 134         /* Checksum invalid? Ignore. */
 135         if (nf_conntrack_checksum && !skb_csum_unnecessary(skb) &&
 136             ((pf == PF_INET && hooknum == NF_IP_PRE_ROUTING) ||
 137              (pf == PF_INET6 && hooknum == NF_IP6_PRE_ROUTING))) {
 138                 if (pf == PF_INET) {
 139                         struct iphdr *iph = ip_hdr(skb);
 140
 141                         skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
 142                                                        udplen, IPPROTO_UDPLITE, 0);
 143                 } else {
 144                         struct ipv6hdr *ipv6h = ipv6_hdr(skb);
 145                         __wsum hsum = skb_checksum(skb, 0, dataoff, 0);
 146
 147                         skb->csum = ~csum_unfold(
 148                                 csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
 149                                                 udplen, IPPROTO_UDPLITE,
 150                                                 csum_sub(0, hsum)));
 151                 }
 152
 153                 skb->ip_summed = CHECKSUM_NONE;
 154                 if (__skb_checksum_complete_head(skb, dataoff + cscov)) {
 155                         if (LOG_INVALID(IPPROTO_UDPLITE))
 156                                 nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 157                                               "nf_ct_udplite: bad UDPLite "
 158                                               "checksum ");
 159                         return -NF_ACCEPT;
 160                 }
 161                 skb->ip_summed = CHECKSUM_UNNECESSARY;
 162         }
 163
 164         return NF_ACCEPT;
 165 }
 166
 167 #ifdef CONFIG_SYSCTL
 168 static unsigned int udplite_sysctl_table_users;
 169 static struct ctl_table_header *udplite_sysctl_header;
 170 static struct ctl_table udplite_sysctl_table[] = {
 171         {
 172                 .ctl_name       = CTL_UNNUMBERED,
 173                 .procname       = "nf_conntrack_udplite_timeout",
 174                 .data           = &nf_ct_udplite_timeout,
 175                 .maxlen         = sizeof(unsigned int),
 176                 .mode           = 0644,
 177                 .proc_handler   = &proc_dointvec_jiffies,
 178         },
 179         {
 180                 .ctl_name       = CTL_UNNUMBERED,
 181                 .procname       = "nf_conntrack_udplite_timeout_stream",
 182                 .data           = &nf_ct_udplite_timeout_stream,
 183                 .maxlen         = sizeof(unsigned int),
 184                 .mode           = 0644,
 185                 .proc_handler   = &proc_dointvec_jiffies,
 186         },
 187         {
 188                 .ctl_name       = 0
 189         }
 190 };
 191 #endif /* CONFIG_SYSCTL */
 192
 193 static struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite4 __read_mostly =
 194 {
 195         .l3proto                = PF_INET,
 196         .l4proto                = IPPROTO_UDPLITE,
 197         .name                   = "udplite",
 198         .pkt_to_tuple           = udplite_pkt_to_tuple,
 199         .invert_tuple           = udplite_invert_tuple,
 200         .print_tuple            = udplite_print_tuple,
 201         .print_conntrack        = udplite_print_conntrack,
 202         .packet                 = udplite_packet,
 203         .new                    = udplite_new,
 204         .error                  = udplite_error,
 205 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 206         .tuple_to_nfattr        = nf_ct_port_tuple_to_nfattr,
 207         .nfattr_to_tuple        = nf_ct_port_nfattr_to_tuple,
 208 #endif
 209 #ifdef CONFIG_SYSCTL
 210         .ctl_table_users        = &udplite_sysctl_table_users,
 211         .ctl_table_header       = &udplite_sysctl_header,
 212         .ctl_table              = udplite_sysctl_table,
 213 #endif
 214 };
 215
 216 static struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite6 __read_mostly =
 217 {
 218         .l3proto                = PF_INET6,
 219         .l4proto                = IPPROTO_UDPLITE,
 220         .name                   = "udplite",
 221         .pkt_to_tuple           = udplite_pkt_to_tuple,
 222         .invert_tuple           = udplite_invert_tuple,
 223         .print_tuple            = udplite_print_tuple,
 224         .print_conntrack        = udplite_print_conntrack,
 225         .packet                 = udplite_packet,
 226         .new                    = udplite_new,
 227         .error                  = udplite_error,
 228 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
 229         .tuple_to_nfattr        = nf_ct_port_tuple_to_nfattr,
 230         .nfattr_to_tuple        = nf_ct_port_nfattr_to_tuple,
 231 #endif
 232 #ifdef CONFIG_SYSCTL
 233         .ctl_table_users        = &udplite_sysctl_table_users,
 234         .ctl_table_header       = &udplite_sysctl_header,
 235         .ctl_table              = udplite_sysctl_table,
 236 #endif
 237 };
 238
 239 static int __init nf_conntrack_proto_udplite_init(void)
 240 {
 241         int err;
 242
 243         err = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udplite4);
 244         if (err < 0)
 245                 goto err1;
 246         err = nf_conntrack_l4proto_register(&nf_conntrack_l4proto_udplite6);
 247         if (err < 0)
 248                 goto err2;
 249         return 0;
 250 err2:
 251         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite4);
 252 err1:
 253         return err;
 254 }
 255
 256 static void __exit nf_conntrack_proto_udplite_exit(void)
 257 {
 258         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite6);
 259         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_udplite4);
 260 }
 261
 262 module_init(nf_conntrack_proto_udplite_init);
 263 module_exit(nf_conntrack_proto_udplite_exit);
 264
 265 MODULE_LICENSE("GPL");