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