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         unsigned long status;
  92
  93         if (udp_error(skb, dataoff, state))
  94                 return -NF_ACCEPT;
  95
  96         timeouts = nf_ct_timeout_lookup(ct);
  97         if (!timeouts)
  98                 timeouts = udp_get_timeouts(nf_ct_net(ct));
  99
 100         status = READ_ONCE(ct->status);
 101         if ((status & IPS_CONFIRMED) == 0)
 102                 ct->proto.udp.stream_ts = 2 * HZ + jiffies;
 103
 104         /* If we've seen traffic both ways, this is some kind of UDP
 105          * stream. Set Assured.
 106          */
 107         if (status & IPS_SEEN_REPLY) {
 108                 unsigned long extra = timeouts[UDP_CT_UNREPLIED];
 109                 bool stream = false;
 110
 111                 /* Still active after two seconds? Extend timeout. */
 112                 if (time_after(jiffies, ct->proto.udp.stream_ts)) {
 113                         extra = timeouts[UDP_CT_REPLIED];
 114                         stream = (status & IPS_ASSURED) == 0;
 115                 }
 116
 117                 nf_ct_refresh_acct(ct, ctinfo, skb, extra);
 118
 119                 /* never set ASSURED for IPS_NAT_CLASH, they time out soon */
 120                 if (unlikely((status & IPS_NAT_CLASH)))
 121                         return NF_ACCEPT;
 122
 123                 /* Also, more likely to be important, and not a probe */
 124                 if (stream && !test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
 125                         nf_conntrack_event_cache(IPCT_ASSURED, ct);
 126         } else {
 127                 nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[UDP_CT_UNREPLIED]);
 128         }
 129         return NF_ACCEPT;
 130 }
 131
 132 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
 133 static void udplite_error_log(const struct sk_buff *skb,
 134                               const struct nf_hook_state *state,
 135                               const char *msg)
 136 {
 137         nf_l4proto_log_invalid(skb, state, IPPROTO_UDPLITE, "%s", msg);
 138 }
 139
 140 static bool udplite_error(struct sk_buff *skb,
 141                           unsigned int dataoff,
 142                           const struct nf_hook_state *state)
 143 {
 144         unsigned int udplen = skb->len - dataoff;
 145         const struct udphdr *hdr;
 146         struct udphdr _hdr;
 147         unsigned int cscov;
 148
 149         /* Header is too small? */
 150         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 151         if (!hdr) {
 152                 udplite_error_log(skb, state, "short packet");
 153                 return true;
 154         }
 155
 156         cscov = ntohs(hdr->len);
 157         if (cscov == 0) {
 158                 cscov = udplen;
 159         } else if (cscov < sizeof(*hdr) || cscov > udplen) {
 160                 udplite_error_log(skb, state, "invalid checksum coverage");
 161                 return true;
 162         }
 163
 164         /* UDPLITE mandates checksums */
 165         if (!hdr->check) {
 166                 udplite_error_log(skb, state, "checksum missing");
 167                 return true;
 168         }
 169
 170         /* Checksum invalid? Ignore. */
 171         if (state->hook == NF_INET_PRE_ROUTING &&
 172             state->net->ct.sysctl_checksum &&
 173             nf_checksum_partial(skb, state->hook, dataoff, cscov, IPPROTO_UDP,
 174                                 state->pf)) {
 175                 udplite_error_log(skb, state, "bad checksum");
 176                 return true;
 177         }
 178
 179         return false;
 180 }
 181
 182 /* Returns verdict for packet, and may modify conntracktype */
 183 int nf_conntrack_udplite_packet(struct nf_conn *ct,
 184                                 struct sk_buff *skb,
 185                                 unsigned int dataoff,
 186                                 enum ip_conntrack_info ctinfo,
 187                                 const struct nf_hook_state *state)
 188 {
 189         unsigned int *timeouts;
 190
 191         if (udplite_error(skb, dataoff, state))
 192                 return -NF_ACCEPT;
 193
 194         timeouts = nf_ct_timeout_lookup(ct);
 195         if (!timeouts)
 196                 timeouts = udp_get_timeouts(nf_ct_net(ct));
 197
 198         /* If we've seen traffic both ways, this is some kind of UDP
 199            stream.  Extend timeout. */
 200         if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
 201                 nf_ct_refresh_acct(ct, ctinfo, skb,
 202                                    timeouts[UDP_CT_REPLIED]);
 203
 204                 if (unlikely((ct->status & IPS_NAT_CLASH)))
 205                         return NF_ACCEPT;
 206
 207                 /* Also, more likely to be important, and not a probe */
 208                 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
 209                         nf_conntrack_event_cache(IPCT_ASSURED, ct);
 210         } else {
 211                 nf_ct_refresh_acct(ct, ctinfo, skb, timeouts[UDP_CT_UNREPLIED]);
 212         }
 213         return NF_ACCEPT;
 214 }
 215 #endif
 216
 217 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 218
 219 #include <linux/netfilter/nfnetlink.h>
 220 #include <linux/netfilter/nfnetlink_cttimeout.h>
 221
 222 static int udp_timeout_nlattr_to_obj(struct nlattr *tb[],
 223                                      struct net *net, void *data)
 224 {
 225         unsigned int *timeouts = data;
 226         struct nf_udp_net *un = nf_udp_pernet(net);
 227
 228         if (!timeouts)
 229                 timeouts = un->timeouts;
 230
 231         /* set default timeouts for UDP. */
 232         timeouts[UDP_CT_UNREPLIED] = un->timeouts[UDP_CT_UNREPLIED];
 233         timeouts[UDP_CT_REPLIED] = un->timeouts[UDP_CT_REPLIED];
 234
 235         if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) {
 236                 timeouts[UDP_CT_UNREPLIED] =
 237                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ;
 238         }
 239         if (tb[CTA_TIMEOUT_UDP_REPLIED]) {
 240                 timeouts[UDP_CT_REPLIED] =
 241                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ;
 242         }
 243         return 0;
 244 }
 245
 246 static int
 247 udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
 248 {
 249         const unsigned int *timeouts = data;
 250
 251         if (nla_put_be32(skb, CTA_TIMEOUT_UDP_UNREPLIED,
 252                          htonl(timeouts[UDP_CT_UNREPLIED] / HZ)) ||
 253             nla_put_be32(skb, CTA_TIMEOUT_UDP_REPLIED,
 254                          htonl(timeouts[UDP_CT_REPLIED] / HZ)))
 255                 goto nla_put_failure;
 256         return 0;
 257
 258 nla_put_failure:
 259         return -ENOSPC;
 260 }
 261
 262 static const struct nla_policy
 263 udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = {
 264        [CTA_TIMEOUT_UDP_UNREPLIED]      = { .type = NLA_U32 },
 265        [CTA_TIMEOUT_UDP_REPLIED]        = { .type = NLA_U32 },
 266 };
 267 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 268
 269 void nf_conntrack_udp_init_net(struct net *net)
 270 {
 271         struct nf_udp_net *un = nf_udp_pernet(net);
 272         int i;
 273
 274         for (i = 0; i < UDP_CT_MAX; i++)
 275                 un->timeouts[i] = udp_timeouts[i];
 276
 277 #if IS_ENABLED(CONFIG_NF_FLOW_TABLE)
 278         un->offload_timeout = 30 * HZ;
 279 #endif
 280 }
 281
 282 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udp =
 283 {
 284         .l4proto                = IPPROTO_UDP,
 285         .allow_clash            = true,
 286 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 287         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 288         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 289         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 290         .nla_policy             = nf_ct_port_nla_policy,
 291 #endif
 292 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 293         .ctnl_timeout           = {
 294                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 295                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 296                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 297                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 298                 .nla_policy     = udp_timeout_nla_policy,
 299         },
 300 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 301 };
 302
 303 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
 304 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite =
 305 {
 306         .l4proto                = IPPROTO_UDPLITE,
 307         .allow_clash            = true,
 308 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
 309         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
 310         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
 311         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
 312         .nla_policy             = nf_ct_port_nla_policy,
 313 #endif
 314 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
 315         .ctnl_timeout           = {
 316                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
 317                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
 318                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
 319                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
 320                 .nla_policy     = udp_timeout_nla_policy,
 321         },
 322 #endif /* CONFIG_NF_CONNTRACK_TIMEOUT */
 323 };
 324 #endif