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

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