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