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TOMOYO Linux Cross Reference
Linux/net/netfilter/nf_conntrack_proto_udp.c

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  1 /* (C) 1999-2001 Paul `Rusty' Russell
  2  * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
  3  * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
  4  *
  5  * This program is free software; you can redistribute it and/or modify
  6  * it under the terms of the GNU General Public License version 2 as
  7  * published by the Free Software Foundation.
  8  */
  9 
 10 #include <linux/types.h>
 11 #include <linux/timer.h>
 12 #include <linux/module.h>
 13 #include <linux/udp.h>
 14 #include <linux/seq_file.h>
 15 #include <linux/skbuff.h>
 16 #include <linux/ipv6.h>
 17 #include <net/ip6_checksum.h>
 18 #include <net/checksum.h>
 19 
 20 #include <linux/netfilter.h>
 21 #include <linux/netfilter_ipv4.h>
 22 #include <linux/netfilter_ipv6.h>
 23 #include <net/netfilter/nf_conntrack_l4proto.h>
 24 #include <net/netfilter/nf_conntrack_ecache.h>
 25 #include <net/netfilter/nf_log.h>
 26 #include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
 27 #include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
 28 
 29 static const unsigned int udp_timeouts[UDP_CT_MAX] = {
 30         [UDP_CT_UNREPLIED]      = 30*HZ,
 31         [UDP_CT_REPLIED]        = 180*HZ,
 32 };
 33 
 34 static inline struct nf_udp_net *udp_pernet(struct net *net)
 35 {
 36         return &net->ct.nf_ct_proto.udp;
 37 }
 38 
 39 static bool udp_pkt_to_tuple(const struct sk_buff *skb,
 40                              unsigned int dataoff,
 41                              struct net *net,
 42                              struct nf_conntrack_tuple *tuple)
 43 {
 44         const struct udphdr *hp;
 45         struct udphdr _hdr;
 46 
 47         /* Actually only need first 4 bytes to get ports. */
 48         hp = skb_header_pointer(skb, dataoff, 4, &_hdr);
 49         if (hp == NULL)
 50                 return false;
 51 
 52         tuple->src.u.udp.port = hp->source;
 53         tuple->dst.u.udp.port = hp->dest;
 54 
 55         return true;
 56 }
 57 
 58 static bool udp_invert_tuple(struct nf_conntrack_tuple *tuple,
 59                              const struct nf_conntrack_tuple *orig)
 60 {
 61         tuple->src.u.udp.port = orig->dst.u.udp.port;
 62         tuple->dst.u.udp.port = orig->src.u.udp.port;
 63         return true;
 64 }
 65 
 66 static unsigned int *udp_get_timeouts(struct net *net)
 67 {
 68         return udp_pernet(net)->timeouts;
 69 }
 70 
 71 /* Returns verdict for packet, and may modify conntracktype */
 72 static int udp_packet(struct nf_conn *ct,
 73                       const struct sk_buff *skb,
 74                       unsigned int dataoff,
 75                       enum ip_conntrack_info ctinfo,
 76                       unsigned int *timeouts)
 77 {
 78         /* If we've seen traffic both ways, this is some kind of UDP
 79            stream.  Extend timeout. */
 80         if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
 81                 nf_ct_refresh_acct(ct, ctinfo, skb,
 82                                    timeouts[UDP_CT_REPLIED]);
 83                 /* Also, more likely to be important, and not a probe */
 84                 if (!test_and_set_bit(IPS_ASSURED_BIT, &ct->status))
 85                         nf_conntrack_event_cache(IPCT_ASSURED, ct);
 86         } else {
 87                 nf_ct_refresh_acct(ct, ctinfo, skb,
 88                                    timeouts[UDP_CT_UNREPLIED]);
 89         }
 90         return NF_ACCEPT;
 91 }
 92 
 93 /* Called when a new connection for this protocol found. */
 94 static bool udp_new(struct nf_conn *ct, const struct sk_buff *skb,
 95                     unsigned int dataoff, unsigned int *timeouts)
 96 {
 97         return true;
 98 }
 99 
100 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
101 static void udplite_error_log(const struct sk_buff *skb, struct net *net,
102                               u8 pf, const char *msg)
103 {
104         nf_l4proto_log_invalid(skb, net, pf, IPPROTO_UDPLITE, "%s", msg);
105 }
106 
107 static int udplite_error(struct net *net, struct nf_conn *tmpl,
108                          struct sk_buff *skb,
109                          unsigned int dataoff,
110                          u8 pf, unsigned int hooknum)
111 {
112         unsigned int udplen = skb->len - dataoff;
113         const struct udphdr *hdr;
114         struct udphdr _hdr;
115         unsigned int cscov;
116 
117         /* Header is too small? */
118         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
119         if (!hdr) {
120                 udplite_error_log(skb, net, pf, "short packet");
121                 return -NF_ACCEPT;
122         }
123 
124         cscov = ntohs(hdr->len);
125         if (cscov == 0) {
126                 cscov = udplen;
127         } else if (cscov < sizeof(*hdr) || cscov > udplen) {
128                 udplite_error_log(skb, net, pf, "invalid checksum coverage");
129                 return -NF_ACCEPT;
130         }
131 
132         /* UDPLITE mandates checksums */
133         if (!hdr->check) {
134                 udplite_error_log(skb, net, pf, "checksum missing");
135                 return -NF_ACCEPT;
136         }
137 
138         /* Checksum invalid? Ignore. */
139         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
140             nf_checksum_partial(skb, hooknum, dataoff, cscov, IPPROTO_UDP,
141                                 pf)) {
142                 udplite_error_log(skb, net, pf, "bad checksum");
143                 return -NF_ACCEPT;
144         }
145 
146         return NF_ACCEPT;
147 }
148 #endif
149 
150 static void udp_error_log(const struct sk_buff *skb, struct net *net,
151                           u8 pf, const char *msg)
152 {
153         nf_l4proto_log_invalid(skb, net, pf, IPPROTO_UDP, "%s", msg);
154 }
155 
156 static int udp_error(struct net *net, struct nf_conn *tmpl, struct sk_buff *skb,
157                      unsigned int dataoff,
158                      u_int8_t pf,
159                      unsigned int hooknum)
160 {
161         unsigned int udplen = skb->len - dataoff;
162         const struct udphdr *hdr;
163         struct udphdr _hdr;
164 
165         /* Header is too small? */
166         hdr = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
167         if (hdr == NULL) {
168                 udp_error_log(skb, net, pf, "short packet");
169                 return -NF_ACCEPT;
170         }
171 
172         /* Truncated/malformed packets */
173         if (ntohs(hdr->len) > udplen || ntohs(hdr->len) < sizeof(*hdr)) {
174                 udp_error_log(skb, net, pf, "truncated/malformed packet");
175                 return -NF_ACCEPT;
176         }
177 
178         /* Packet with no checksum */
179         if (!hdr->check)
180                 return NF_ACCEPT;
181 
182         /* Checksum invalid? Ignore.
183          * We skip checking packets on the outgoing path
184          * because the checksum is assumed to be correct.
185          * FIXME: Source route IP option packets --RR */
186         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
187             nf_checksum(skb, hooknum, dataoff, IPPROTO_UDP, pf)) {
188                 udp_error_log(skb, net, pf, "bad checksum");
189                 return -NF_ACCEPT;
190         }
191 
192         return NF_ACCEPT;
193 }
194 
195 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
196 
197 #include <linux/netfilter/nfnetlink.h>
198 #include <linux/netfilter/nfnetlink_cttimeout.h>
199 
200 static int udp_timeout_nlattr_to_obj(struct nlattr *tb[],
201                                      struct net *net, void *data)
202 {
203         unsigned int *timeouts = data;
204         struct nf_udp_net *un = udp_pernet(net);
205 
206         /* set default timeouts for UDP. */
207         timeouts[UDP_CT_UNREPLIED] = un->timeouts[UDP_CT_UNREPLIED];
208         timeouts[UDP_CT_REPLIED] = un->timeouts[UDP_CT_REPLIED];
209 
210         if (tb[CTA_TIMEOUT_UDP_UNREPLIED]) {
211                 timeouts[UDP_CT_UNREPLIED] =
212                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_UNREPLIED])) * HZ;
213         }
214         if (tb[CTA_TIMEOUT_UDP_REPLIED]) {
215                 timeouts[UDP_CT_REPLIED] =
216                         ntohl(nla_get_be32(tb[CTA_TIMEOUT_UDP_REPLIED])) * HZ;
217         }
218         return 0;
219 }
220 
221 static int
222 udp_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
223 {
224         const unsigned int *timeouts = data;
225 
226         if (nla_put_be32(skb, CTA_TIMEOUT_UDP_UNREPLIED,
227                          htonl(timeouts[UDP_CT_UNREPLIED] / HZ)) ||
228             nla_put_be32(skb, CTA_TIMEOUT_UDP_REPLIED,
229                          htonl(timeouts[UDP_CT_REPLIED] / HZ)))
230                 goto nla_put_failure;
231         return 0;
232 
233 nla_put_failure:
234         return -ENOSPC;
235 }
236 
237 static const struct nla_policy
238 udp_timeout_nla_policy[CTA_TIMEOUT_UDP_MAX+1] = {
239        [CTA_TIMEOUT_UDP_UNREPLIED]      = { .type = NLA_U32 },
240        [CTA_TIMEOUT_UDP_REPLIED]        = { .type = NLA_U32 },
241 };
242 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
243 
244 #ifdef CONFIG_SYSCTL
245 static struct ctl_table udp_sysctl_table[] = {
246         {
247                 .procname       = "nf_conntrack_udp_timeout",
248                 .maxlen         = sizeof(unsigned int),
249                 .mode           = 0644,
250                 .proc_handler   = proc_dointvec_jiffies,
251         },
252         {
253                 .procname       = "nf_conntrack_udp_timeout_stream",
254                 .maxlen         = sizeof(unsigned int),
255                 .mode           = 0644,
256                 .proc_handler   = proc_dointvec_jiffies,
257         },
258         { }
259 };
260 #endif /* CONFIG_SYSCTL */
261 
262 static int udp_kmemdup_sysctl_table(struct nf_proto_net *pn,
263                                     struct nf_udp_net *un)
264 {
265 #ifdef CONFIG_SYSCTL
266         if (pn->ctl_table)
267                 return 0;
268         pn->ctl_table = kmemdup(udp_sysctl_table,
269                                 sizeof(udp_sysctl_table),
270                                 GFP_KERNEL);
271         if (!pn->ctl_table)
272                 return -ENOMEM;
273         pn->ctl_table[0].data = &un->timeouts[UDP_CT_UNREPLIED];
274         pn->ctl_table[1].data = &un->timeouts[UDP_CT_REPLIED];
275 #endif
276         return 0;
277 }
278 
279 static int udp_init_net(struct net *net, u_int16_t proto)
280 {
281         struct nf_udp_net *un = udp_pernet(net);
282         struct nf_proto_net *pn = &un->pn;
283 
284         if (!pn->users) {
285                 int i;
286 
287                 for (i = 0; i < UDP_CT_MAX; i++)
288                         un->timeouts[i] = udp_timeouts[i];
289         }
290 
291         return udp_kmemdup_sysctl_table(pn, un);
292 }
293 
294 static struct nf_proto_net *udp_get_net_proto(struct net *net)
295 {
296         return &net->ct.nf_ct_proto.udp.pn;
297 }
298 
299 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udp4 =
300 {
301         .l3proto                = PF_INET,
302         .l4proto                = IPPROTO_UDP,
303         .allow_clash            = true,
304         .pkt_to_tuple           = udp_pkt_to_tuple,
305         .invert_tuple           = udp_invert_tuple,
306         .packet                 = udp_packet,
307         .get_timeouts           = udp_get_timeouts,
308         .new                    = udp_new,
309         .error                  = udp_error,
310 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
311         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
312         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
313         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
314         .nla_policy             = nf_ct_port_nla_policy,
315 #endif
316 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
317         .ctnl_timeout           = {
318                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
319                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
320                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
321                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
322                 .nla_policy     = udp_timeout_nla_policy,
323         },
324 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
325         .init_net               = udp_init_net,
326         .get_net_proto          = udp_get_net_proto,
327 };
328 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp4);
329 
330 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
331 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite4 =
332 {
333         .l3proto                = PF_INET,
334         .l4proto                = IPPROTO_UDPLITE,
335         .allow_clash            = true,
336         .pkt_to_tuple           = udp_pkt_to_tuple,
337         .invert_tuple           = udp_invert_tuple,
338         .packet                 = udp_packet,
339         .get_timeouts           = udp_get_timeouts,
340         .new                    = udp_new,
341         .error                  = udplite_error,
342 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
343         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
344         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
345         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
346         .nla_policy             = nf_ct_port_nla_policy,
347 #endif
348 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
349         .ctnl_timeout           = {
350                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
351                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
352                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
353                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
354                 .nla_policy     = udp_timeout_nla_policy,
355         },
356 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
357         .init_net               = udp_init_net,
358         .get_net_proto          = udp_get_net_proto,
359 };
360 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udplite4);
361 #endif
362 
363 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udp6 =
364 {
365         .l3proto                = PF_INET6,
366         .l4proto                = IPPROTO_UDP,
367         .allow_clash            = true,
368         .pkt_to_tuple           = udp_pkt_to_tuple,
369         .invert_tuple           = udp_invert_tuple,
370         .packet                 = udp_packet,
371         .get_timeouts           = udp_get_timeouts,
372         .new                    = udp_new,
373         .error                  = udp_error,
374 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
375         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
376         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
377         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
378         .nla_policy             = nf_ct_port_nla_policy,
379 #endif
380 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
381         .ctnl_timeout           = {
382                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
383                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
384                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
385                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
386                 .nla_policy     = udp_timeout_nla_policy,
387         },
388 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
389         .init_net               = udp_init_net,
390         .get_net_proto          = udp_get_net_proto,
391 };
392 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udp6);
393 
394 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
395 const struct nf_conntrack_l4proto nf_conntrack_l4proto_udplite6 =
396 {
397         .l3proto                = PF_INET6,
398         .l4proto                = IPPROTO_UDPLITE,
399         .allow_clash            = true,
400         .pkt_to_tuple           = udp_pkt_to_tuple,
401         .invert_tuple           = udp_invert_tuple,
402         .packet                 = udp_packet,
403         .get_timeouts           = udp_get_timeouts,
404         .new                    = udp_new,
405         .error                  = udplite_error,
406 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
407         .tuple_to_nlattr        = nf_ct_port_tuple_to_nlattr,
408         .nlattr_to_tuple        = nf_ct_port_nlattr_to_tuple,
409         .nlattr_tuple_size      = nf_ct_port_nlattr_tuple_size,
410         .nla_policy             = nf_ct_port_nla_policy,
411 #endif
412 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
413         .ctnl_timeout           = {
414                 .nlattr_to_obj  = udp_timeout_nlattr_to_obj,
415                 .obj_to_nlattr  = udp_timeout_obj_to_nlattr,
416                 .nlattr_max     = CTA_TIMEOUT_UDP_MAX,
417                 .obj_size       = sizeof(unsigned int) * CTA_TIMEOUT_UDP_MAX,
418                 .nla_policy     = udp_timeout_nla_policy,
419         },
420 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
421         .init_net               = udp_init_net,
422         .get_net_proto          = udp_get_net_proto,
423 };
424 EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_udplite6);
425 #endif
426 

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