net/netfilter/nf_conntrack_proto_udp.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* (C) 1999-2001 Paul `Rusty' Russell
   3  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
   4  * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
   5  */
   6
   7 #include <linux/types.h>
   8 #include <linux/timer.h>
   9 #include <linux/module.h>
  10 #include <linux/udp.h>
  11 #include <linux/seq_file.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/ipv6.h>
  14 #include <net/ip6_checksum.h>
  15 #include <net/checksum.h>
  16
  17 #include <linux/netfilter.h>
  18 #include <linux/netfilter_ipv4.h>
  19 #include <linux/netfilter_ipv6.h>
  20 #include <net/netfilter/nf_conntrack_l4proto.h>
  21 #include <net/netfilter/nf_conntrack_ecache.h>
  22 #include <net/netfilter/nf_conntrack_timeout.h>
  23 #include <net/netfilter/nf_log.h>
  24 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
  25 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
  26
  27 static const unsigned int udp_timeouts[UDP_CT_MAX] = {
  28         [UDP_CT_UNREPLIED]      = 30*HZ,
  29         [UDP_CT_REPLIED]        = 120*HZ,
  30 };
  31
  32 static unsigned int *udp_get_timeouts(struct net *net)
  33 {
  34         return nf_udp_pernet(net)->timeouts;
  35 }
  36
  37 static void udp_error_log(const struct sk_buff *skb,
  38                           const struct nf_hook_state *state,
  39                           const char *msg)
  40 {
  41         nf_l4proto_log_invalid(skb, state->net, state->pf,
  42                                IPPROTO_UDP, "%s", msg);
  43 }
  44
  45 static bool udp_error(struct sk_buff *skb,
  46                       unsigned int dataoff,
  47                       const struct nf_hook_state *state)
  48 {
  49         unsigned int udplen = skb->len - dataoff;
  50         const struct udphdr *hdr;
  51         struct udphdr _hdr;
  52
  53         /* Header is too small? */
  54         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
  55         if (!hdr) {
  56                 udp_error_log(skb, state, "short packet");
  57                 return true;
  58         }
  59
  60         /* Truncated/malformed packets */
  61         if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
  62                 udp_error_log(skb, state, "truncated/malformed packet");
  63                 return true;
  64         }
  65
  66         /* Packet with no checksum */
  67         if (!hdr->check)
  68                 return false;
  69
  70         /* Checksum invalid? Ignore.
  71          * We skip checking packets on the outgoing path
  72          * because the checksum is assumed to be correct.
  73          * FIXME: Source route IP option packets --RR */
  74         if (state->hook == NF_INET_PRE_ROUTING &&
  75             state->net->ct.sysctl_checksum &&
  76             nf_checksum(skb, state->hook, dataoff, IPPROTO_UDP, state->pf)) {
  77                 udp_error_log(skb, state, "bad checksum");
  78                 return true;
  79         }
  80
  81         return false;
  82 }
  83
  84 static void nf_conntrack_udp_refresh_unreplied(struct nf_conn *ct,
  85                                                struct sk_buff *skb,
  86                                                enum ip_conntrack_info ctinfo,
  87                                                u32 extra_jiffies)
  88 {
  89         if (unlikely(ctinfo == IP_CT_ESTABLISHED_REPLY &&
  90                      ct->status & IPS_NAT_CLASH))
  91                 nf_ct_kill(ct);
  92         else
  93                 nf_ct_refresh_acct(ct, ctinfo, skb, extra_jiffies);
  94 }
  95
  96 /* Returns verdict for packet, and may modify conntracktype */
  97 int nf_conntrack_udp_packet(struct nf_conn *ct,
  98                             struct sk_buff *skb,
  99                             unsigned int dataoff,
 100                             enum ip_conntrack_info ctinfo,
 101                             const struct nf_hook_state *state)
 102 {
 103         unsigned int *timeouts;
 104
 105         if (udp_error(skb, dataoff, state))
 106                 return -NF_ACCEPT;
 107
 108         timeouts = nf_ct_timeout_lookup(ct);
 109         if (!timeouts)
 110                 timeouts = udp_get_timeouts(nf_ct_net(ct));
 111
 112         if (!nf_ct_is_confirmed(ct))
 113                 ct->proto.udp.stream_ts = 2 * HZ + jiffies;
 114
 115         /* If we've seen traffic both ways, this is some kind of UDP
 116          * stream. Set Assured.
 117          */
 118         if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
 119                 unsigned long extra = timeouts[UDP_CT_UNREPLIED];
 120
 121                 /* Still active after two seconds? Extend timeout. */
 122                 if (time_after(jiffies, ct->proto.udp.stream_ts))
 123                         extra = timeouts[UDP_CT_REPLIED];
 124
 125                 nf_ct_refresh_acct(ct, ctinfo, skb, extra);
 126
 127                 /* Also, more likely to be important, and not a probe */
 128                 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
 129                         nf_conntrack_event_cache(IPCT_ASSURED, ct);
 130         } else {
 131                 nf_conntrack_udp_refresh_unreplied(ct, skb, ctinfo,
 132                                                    timeouts[UDP_CT_UNREPLIED]);
 133         }
 134         return NF_ACCEPT;
 135 }
 136
 137 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
 138 static void udplite_error_log(const struct sk_buff *skb,
 139                               const struct nf_hook_state *state,
 140                               const char *msg)
 141 {
 142         nf_l4proto_log_invalid(skb, state->net, state->pf,
 143                                IPPROTO_UDPLITE, "%s", msg);
 144 }
 145
 146 static bool udplite_error(struct sk_buff *skb,
 147                           unsigned int dataoff,
 148                           const struct nf_hook_state *state)
 149 {
 150         unsigned int udplen = skb->len - dataoff;
 151         const struct udphdr *hdr;
 152         struct udphdr _hdr;
 153         unsigned int cscov;
 154
 155         /* Header is too small? */
 156         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 157         if (!hdr) {
 158                 udplite_error_log(skb, state, "short packet");
 159                 return true;
 160         }
 161
 162         cscov = ntohs(hdr->len);
 163         if (cscov == 0) {
 164                 cscov = udplen;
 165         } else if (cscov < sizeof(*hdr) || cscov > udplen) {
 166                 udplite_error_log(skb, state, "invalid checksum coverage");
 167                 return true;
 168         }
 169
 170         /* UDPLITE mandates checksums */
 171         if (!hdr->check) {
 172                 udplite_error_log(skb, state, "checksum missing");
 173                 return true;
 174         }
 175
 176         /* Checksum invalid? Ignore. */
 177         if (state->hook == NF_INET_PRE_ROUTING &&
 178             state->net->ct.sysctl_checksum &&
 179             nf_checksum_partial(skb, state->hook, dataoff, cscov, IPPROTO_UDP,
 180                                 state->pf)) {
 181                 udplite_error_log(skb, state, "bad checksum");
 182                 return true;
 183         }
 184
 185         return false;
 186 }
 187
 188 /* Returns verdict for packet, and may modify conntracktype */
 189 int nf_conntrack_udplite_packet(struct nf_conn *ct,
 190                                 struct sk_buff *skb,
 191                                 unsigned int dataoff,
 192                                 enum ip_conntrack_info ctinfo,
 193                                 const struct nf_hook_state *state)
 194 {
 195         unsigned int *timeouts;
 196
 197         if (udplite_error(skb, dataoff, state))
 198                 return -NF_ACCEPT;
 199
 200         timeouts = nf_ct_timeout_lookup(ct);
 201         if (!timeouts)
 202                 timeouts = udp_get_timeouts(nf_ct_net(ct));
 203
 204         /* If we've seen traffic both ways, this is some kind of UDP
 205            stream.  Extend timeout. */
 206         if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
 207                 nf_ct_refresh_acct(ct, ctinfo, skb,
 208                                    timeouts[UDP_CT_REPLIED]);
 209                 /* Also, more likely to be important, and not a probe */
 210                 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
 211                         nf_conntrack_event_cache(IPCT_ASSURED, ct);
 212         } else {
 213                 nf_conntrack_udp_refresh_unreplied(ct, skb, ctinfo,
 214                                                    timeouts[UDP_CT_UNREPLIED]);
 215         }
 216         return NF_ACCEPT;
 217 }
 218 #endif
 219
 220 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 221
 222 #include <linux/netfilter/nfnetlink.h>
 223 #include <linux/netfilter/nfnetlink_cttimeout.h>
 224
 225 static int udp_timeout_nlattr_to_obj(struct nlattr *tb[],
 226                                      struct net *net, void *data)
 227 {
 228         unsigned int *timeouts = data;
 229         struct nf_udp_net *un = nf_udp_pernet(net);
 230
 231         if (!timeouts)
 232                 timeouts = un->timeouts;
 233
 234         /* set default timeouts for UDP. */
 235         timeouts[UDP_CT_UNREPLIED] = un->timeouts[UDP_CT_UNREPLIED];
 236         timeouts[UDP_CT_REPLIED] = un->timeouts[UDP_CT_REPLIED];
 237
 238         if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) {
 239                 timeouts[UDP_CT_UNREPLIED] =
 240                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ;
 241         }
 242         if (tb[CTA_TIMEOUT_UDP_REPLIED]) {
 243                 timeouts[UDP_CT_REPLIED] =
 244                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ;
 245         }
 246         return 0;
 247 }
 248
 249 static int
 250 udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 251 {
 252         const unsigned int *timeouts = data;
 253
 254         if (nla_put_be32(skb, CTA_TIMEOUT_UDP_UNREPLIED,
 255                          htonl(timeouts[UDP_CT_UNREPLIED] / HZ)) ||
 256             nla_put_be32(skb, CTA_TIMEOUT_UDP_REPLIED,
 257                          htonl(timeouts[UDP_CT_REPLIED] / HZ)))
 258                 goto nla_put_failure;
 259         return 0;
 260
 261 nla_put_failure:
 262         return -ENOSPC;
 263 }
 264
 265 static const struct nla_policy
 266 udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = {
 267        [CTA_TIMEOUT_UDP_UNREPLIED]      = { .type = NLA_U32 },
 268        [CTA_TIMEOUT_UDP_REPLIED]        = { .type = NLA_U32 },
 269 };
 270 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 271
 272 void nf_conntrack_udp_init_net(struct net *net)
 273 {
 274         struct nf_udp_net *un = nf_udp_pernet(net);
 275         int i;
 276
 277         for (i = 0; i < UDP_CT_MAX; i++)
 278                 un->timeouts[i] = udp_timeouts[i];
 279 }
 280
 281 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udp =
 282 {
 283         .l4proto                = IPPROTO_UDP,
 284         .allow_clash            = true,
 285 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 286         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 287         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 288         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 289         .nla_policy             = nf_ct_port_nla_policy,
 290 #endif
 291 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 292         .ctnl_timeout           = {
 293                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 294                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 295                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 296                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 297                 .nla_policy     = udp_timeout_nla_policy,
 298         },
 299 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 300 };
 301
 302 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
 303 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite =
 304 {
 305         .l4proto                = IPPROTO_UDPLITE,
 306         .allow_clash            = true,
 307 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 308         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 309         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 310         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 311         .nla_policy             = nf_ct_port_nla_policy,
 312 #endif
 313 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 314         .ctnl_timeout           = {
 315                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 316                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 317                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 318                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 319                 .nla_policy     = udp_timeout_nla_policy,
 320         },
 321 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 322 };
 323 #endif