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 enum udp_conntrack {
  29         UDP_CT_UNREPLIED,
  30         UDP_CT_REPLIED,
  31         UDP_CT_MAX
  32 };
  33
  34 static unsigned int udp_timeouts[UDP_CT_MAX] = {
  35         [UDP_CT_UNREPLIED]      = 30*HZ,
  36         [UDP_CT_REPLIED]        = 180*HZ,
  37 };
  38
  39 static bool udp_pkt_to_tuple(const struct sk_buff *skb,
  40                              unsigned int dataoff,
  41                              struct nf_conntrack_tuple *tuple)
  42 {
  43         const struct udphdr *hp;
  44         struct udphdr _hdr;
  45
  46         /* Actually only need first 8 bytes. */
  47         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  48         if (hp == NULL)
  49                 return false;
  50
  51         tuple->src.u.udp.port = hp->source;
  52         tuple->dst.u.udp.port = hp->dest;
  53
  54         return true;
  55 }
  56
  57 static bool udp_invert_tuple(struct nf_conntrack_tuple *tuple,
  58                              const struct nf_conntrack_tuple *orig)
  59 {
  60         tuple->src.u.udp.port = orig->dst.u.udp.port;
  61         tuple->dst.u.udp.port = orig->src.u.udp.port;
  62         return true;
  63 }
  64
  65 /* Print out the per-protocol part of the tuple. */
  66 static int udp_print_tuple(struct seq_file *s,
  67                            const struct nf_conntrack_tuple *tuple)
  68 {
  69         return seq_printf(s, "sport=%hu dport=%hu ",
  70                           ntohs(tuple->src.u.udp.port),
  71                           ntohs(tuple->dst.u.udp.port));
  72 }
  73
  74 static unsigned int *udp_get_timeouts(struct net *net)
  75 {
  76         return udp_timeouts;
  77 }
  78
  79 /* Returns verdict for packet, and may modify conntracktype */
  80 static int udp_packet(struct nf_conn *ct,
  81                       const struct sk_buff *skb,
  82                       unsigned int dataoff,
  83                       enum ip_conntrack_info ctinfo,
  84                       u_int8_t pf,
  85                       unsigned int hooknum,
  86                       unsigned int *timeouts)
  87 {
  88         /* If we've seen traffic both ways, this is some kind of UDP
  89            stream.  Extend timeout. */
  90         if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
  91                 nf_ct_refresh_acct(ct, ctinfo, skb,
  92                                    timeouts[UDP_CT_REPLIED]);
  93                 /* Also, more likely to be important, and not a probe */
  94                 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
  95                         nf_conntrack_event_cache(IPCT_ASSURED, ct);
  96         } else {
  97                 nf_ct_refresh_acct(ct, ctinfo, skb,
  98                                    timeouts[UDP_CT_UNREPLIED]);
  99         }
 100         return NF_ACCEPT;
 101 }
 102
 103 /* Called when a new connection for this protocol found. */
 104 static bool udp_new(struct nf_conn *ct, const struct sk_buff *skb,
 105                     unsigned int dataoff, unsigned int *timeouts)
 106 {
 107         return true;
 108 }
 109
 110 static int udp_error(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb,
 111                      unsigned int dataoff, enum ip_conntrack_info *ctinfo,
 112                      u_int8_t pf,
 113                      unsigned int hooknum)
 114 {
 115         unsigned int udplen = skb->len - dataoff;
 116         const struct udphdr *hdr;
 117         struct udphdr _hdr;
 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_UDP))
 123                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 124                                       "nf_ct_udp: short packet ");
 125                 return -NF_ACCEPT;
 126         }
 127
 128         /* Truncated/malformed packets */
 129         if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
 130                 if (LOG_INVALID(net, IPPROTO_UDP))
 131                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 132                                 "nf_ct_udp: truncated/malformed packet ");
 133                 return -NF_ACCEPT;
 134         }
 135
 136         /* Packet with no checksum */
 137         if (!hdr->check)
 138                 return NF_ACCEPT;
 139
 140         /* Checksum invalid? Ignore.
 141          * We skip checking packets on the outgoing path
 142          * because the checksum is assumed to be correct.
 143          * FIXME: Source route IP option packets --RR */
 144         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
 145             nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
 146                 if (LOG_INVALID(net, IPPROTO_UDP))
 147                         nf_log_packet(pf, 0, skb, NULL, NULL, NULL,
 148                                 "nf_ct_udp: bad UDP checksum ");
 149                 return -NF_ACCEPT;
 150         }
 151
 152         return NF_ACCEPT;
 153 }
 154
 155 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 156
 157 #include <linux/netfilter/nfnetlink.h>
 158 #include <linux/netfilter/nfnetlink_cttimeout.h>
 159
 160 static int udp_timeout_nlattr_to_obj(struct nlattr *tb[], void *data)
 161 {
 162         unsigned int *timeouts = data;
 163
 164         /* set default timeouts for UDP. */
 165         timeouts[UDP_CT_UNREPLIED] = udp_timeouts[UDP_CT_UNREPLIED];
 166         timeouts[UDP_CT_REPLIED] = udp_timeouts[UDP_CT_REPLIED];
 167
 168         if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) {
 169                 timeouts[UDP_CT_UNREPLIED] =
 170                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ;
 171         }
 172         if (tb[CTA_TIMEOUT_UDP_REPLIED]) {
 173                 timeouts[UDP_CT_REPLIED] =
 174                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ;
 175         }
 176         return 0;
 177 }
 178
 179 static int
 180 udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 181 {
 182         const unsigned int *timeouts = data;
 183
 184         NLA_PUT_BE32(skb, CTA_TIMEOUT_UDP_UNREPLIED,
 185                         htonl(timeouts[UDP_CT_UNREPLIED] / HZ));
 186         NLA_PUT_BE32(skb, CTA_TIMEOUT_UDP_REPLIED,
 187                         htonl(timeouts[UDP_CT_REPLIED] / HZ));
 188         return 0;
 189
 190 nla_put_failure:
 191         return -ENOSPC;
 192 }
 193
 194 static const struct nla_policy
 195 udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = {
 196        [CTA_TIMEOUT_UDP_UNREPLIED]      = { .type = NLA_U32 },
 197        [CTA_TIMEOUT_UDP_REPLIED]        = { .type = NLA_U32 },
 198 };
 199 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 200
 201 #ifdef CONFIG_SYSCTL
 202 static unsigned int udp_sysctl_table_users;
 203 static struct ctl_table_header *udp_sysctl_header;
 204 static struct ctl_table udp_sysctl_table[] = {
 205         {
 206                 .procname       = "nf_conntrack_udp_timeout",
 207                 .data           = &udp_timeouts[UDP_CT_UNREPLIED],
 208                 .maxlen         = sizeof(unsigned int),
 209                 .mode           = 0644,
 210                 .proc_handler   = proc_dointvec_jiffies,
 211         },
 212         {
 213                 .procname       = "nf_conntrack_udp_timeout_stream",
 214                 .data           = &udp_timeouts[UDP_CT_REPLIED],
 215                 .maxlen         = sizeof(unsigned int),
 216                 .mode           = 0644,
 217                 .proc_handler   = proc_dointvec_jiffies,
 218         },
 219         { }
 220 };
 221 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 222 static struct ctl_table udp_compat_sysctl_table[] = {
 223         {
 224                 .procname       = "ip_conntrack_udp_timeout",
 225                 .data           = &udp_timeouts[UDP_CT_UNREPLIED],
 226                 .maxlen         = sizeof(unsigned int),
 227                 .mode           = 0644,
 228                 .proc_handler   = proc_dointvec_jiffies,
 229         },
 230         {
 231                 .procname       = "ip_conntrack_udp_timeout_stream",
 232                 .data           = &udp_timeouts[UDP_CT_REPLIED],
 233                 .maxlen         = sizeof(unsigned int),
 234                 .mode           = 0644,
 235                 .proc_handler   = proc_dointvec_jiffies,
 236         },
 237         { }
 238 };
 239 #endif /* CONFIG_NF_CONNTRACK_PROC_COMPAT */
 240 #endif /* CONFIG_SYSCTL */
 241
 242 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp4 __read_mostly =
 243 {
 244         .l3proto                = PF_INET,
 245         .l4proto                = IPPROTO_UDP,
 246         .name                   = "udp",
 247         .pkt_to_tuple           = udp_pkt_to_tuple,
 248         .invert_tuple           = udp_invert_tuple,
 249         .print_tuple            = udp_print_tuple,
 250         .packet                 = udp_packet,
 251         .get_timeouts           = udp_get_timeouts,
 252         .new                    = udp_new,
 253         .error                  = udp_error,
 254 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 255         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 256         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 257         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 258         .nla_policy             = nf_ct_port_nla_policy,
 259 #endif
 260 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 261         .ctnl_timeout           = {
 262                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 263                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 264                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 265                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 266                 .nla_policy     = udp_timeout_nla_policy,
 267         },
 268 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 269 #ifdef CONFIG_SYSCTL
 270         .ctl_table_users        = &udp_sysctl_table_users,
 271         .ctl_table_header       = &udp_sysctl_header,
 272         .ctl_table              = udp_sysctl_table,
 273 #ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
 274         .ctl_compat_table       = udp_compat_sysctl_table,
 275 #endif
 276 #endif
 277 };
 278 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp4);
 279
 280 struct nf_conntrack_l4proto nf_conntrack_l4proto_udp6 __read_mostly =
 281 {
 282         .l3proto                = PF_INET6,
 283         .l4proto                = IPPROTO_UDP,
 284         .name                   = "udp",
 285         .pkt_to_tuple           = udp_pkt_to_tuple,
 286         .invert_tuple           = udp_invert_tuple,
 287         .print_tuple            = udp_print_tuple,
 288         .packet                 = udp_packet,
 289         .get_timeouts           = udp_get_timeouts,
 290         .new                    = udp_new,
 291         .error                  = udp_error,
 292 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 293         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 294         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 295         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 296         .nla_policy             = nf_ct_port_nla_policy,
 297 #endif
 298 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
 299         .ctnl_timeout           = {
 300                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 301                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 302                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 303                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 304                 .nla_policy     = udp_timeout_nla_policy,
 305         },
 306 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
 307 #ifdef CONFIG_SYSCTL
 308         .ctl_table_users        = &udp_sysctl_table_users,
 309         .ctl_table_header       = &udp_sysctl_header,
 310         .ctl_table              = udp_sysctl_table,
 311 #endif
 312 };
 313 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp6);