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Linux/net/ipv6/netfilter/nf_conntrack_proto_icmpv6.c

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  1 /*
  2  * Copyright (C)2003,2004 USAGI/WIDE Project
  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  * Author:
  9  *      Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
 10  */
 11 
 12 #include <linux/types.h>
 13 #include <linux/timer.h>
 14 #include <linux/module.h>
 15 #include <linux/netfilter.h>
 16 #include <linux/in6.h>
 17 #include <linux/icmpv6.h>
 18 #include <linux/ipv6.h>
 19 #include <net/ipv6.h>
 20 #include <net/ip6_checksum.h>
 21 #include <linux/seq_file.h>
 22 #include <linux/netfilter_ipv6.h>
 23 #include <net/netfilter/nf_conntrack_tuple.h>
 24 #include <net/netfilter/nf_conntrack_l4proto.h>
 25 #include <net/netfilter/nf_conntrack_core.h>
 26 #include <net/netfilter/nf_conntrack_zones.h>
 27 #include <net/netfilter/ipv6/nf_conntrack_icmpv6.h>
 28 #include <net/netfilter/nf_log.h>
 29 
 30 static unsigned int nf_ct_icmpv6_timeout __read_mostly = 30*HZ;
 31 
 32 static inline struct nf_icmp_net *icmpv6_pernet(struct net *net)
 33 {
 34         return &net->ct.nf_ct_proto.icmpv6;
 35 }
 36 
 37 static bool icmpv6_pkt_to_tuple(const struct sk_buff *skb,
 38                                 unsigned int dataoff,
 39                                 struct net *net,
 40                                 struct nf_conntrack_tuple *tuple)
 41 {
 42         const struct icmp6hdr *hp;
 43         struct icmp6hdr _hdr;
 44 
 45         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 46         if (hp == NULL)
 47                 return false;
 48         tuple->dst.u.icmp.type = hp->icmp6_type;
 49         tuple->src.u.icmp.id = hp->icmp6_identifier;
 50         tuple->dst.u.icmp.code = hp->icmp6_code;
 51 
 52         return true;
 53 }
 54 
 55 /* Add 1; spaces filled with 0. */
 56 static const u_int8_t invmap[] = {
 57         [ICMPV6_ECHO_REQUEST - 128]     = ICMPV6_ECHO_REPLY + 1,
 58         [ICMPV6_ECHO_REPLY - 128]       = ICMPV6_ECHO_REQUEST + 1,
 59         [ICMPV6_NI_QUERY - 128]         = ICMPV6_NI_REPLY + 1,
 60         [ICMPV6_NI_REPLY - 128]         = ICMPV6_NI_QUERY + 1
 61 };
 62 
 63 static const u_int8_t noct_valid_new[] = {
 64         [ICMPV6_MGM_QUERY - 130] = 1,
 65         [ICMPV6_MGM_REPORT - 130] = 1,
 66         [ICMPV6_MGM_REDUCTION - 130] = 1,
 67         [NDISC_ROUTER_SOLICITATION - 130] = 1,
 68         [NDISC_ROUTER_ADVERTISEMENT - 130] = 1,
 69         [NDISC_NEIGHBOUR_SOLICITATION - 130] = 1,
 70         [NDISC_NEIGHBOUR_ADVERTISEMENT - 130] = 1,
 71         [ICMPV6_MLD2_REPORT - 130] = 1
 72 };
 73 
 74 static bool icmpv6_invert_tuple(struct nf_conntrack_tuple *tuple,
 75                                 const struct nf_conntrack_tuple *orig)
 76 {
 77         int type = orig->dst.u.icmp.type - 128;
 78         if (type < 0 || type >= sizeof(invmap) || !invmap[type])
 79                 return false;
 80 
 81         tuple->src.u.icmp.id   = orig->src.u.icmp.id;
 82         tuple->dst.u.icmp.type = invmap[type] - 1;
 83         tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
 84         return true;
 85 }
 86 
 87 /* Print out the per-protocol part of the tuple. */
 88 static void icmpv6_print_tuple(struct seq_file *s,
 89                               const struct nf_conntrack_tuple *tuple)
 90 {
 91         seq_printf(s, "type=%u code=%u id=%u ",
 92                    tuple->dst.u.icmp.type,
 93                    tuple->dst.u.icmp.code,
 94                    ntohs(tuple->src.u.icmp.id));
 95 }
 96 
 97 static unsigned int *icmpv6_get_timeouts(struct net *net)
 98 {
 99         return &icmpv6_pernet(net)->timeout;
100 }
101 
102 /* Returns verdict for packet, or -1 for invalid. */
103 static int icmpv6_packet(struct nf_conn *ct,
104                        const struct sk_buff *skb,
105                        unsigned int dataoff,
106                        enum ip_conntrack_info ctinfo,
107                        u_int8_t pf,
108                        unsigned int hooknum,
109                        unsigned int *timeout)
110 {
111         /* Do not immediately delete the connection after the first
112            successful reply to avoid excessive conntrackd traffic
113            and also to handle correctly ICMP echo reply duplicates. */
114         nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
115 
116         return NF_ACCEPT;
117 }
118 
119 /* Called when a new connection for this protocol found. */
120 static bool icmpv6_new(struct nf_conn *ct, const struct sk_buff *skb,
121                        unsigned int dataoff, unsigned int *timeouts)
122 {
123         static const u_int8_t valid_new[] = {
124                 [ICMPV6_ECHO_REQUEST - 128] = 1,
125                 [ICMPV6_NI_QUERY - 128] = 1
126         };
127         int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;
128 
129         if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
130                 /* Can't create a new ICMPv6 `conn' with this. */
131                 pr_debug("icmpv6: can't create new conn with type %u\n",
132                          type + 128);
133                 nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
134                 if (LOG_INVALID(nf_ct_net(ct), IPPROTO_ICMPV6))
135                         nf_log_packet(nf_ct_net(ct), PF_INET6, 0, skb, NULL,
136                                       NULL, NULL,
137                                       "nf_ct_icmpv6: invalid new with type %d ",
138                                       type + 128);
139                 return false;
140         }
141         return true;
142 }
143 
144 static int
145 icmpv6_error_message(struct net *net, struct nf_conn *tmpl,
146                      struct sk_buff *skb,
147                      unsigned int icmp6off,
148                      enum ip_conntrack_info *ctinfo,
149                      unsigned int hooknum)
150 {
151         struct nf_conntrack_tuple intuple, origtuple;
152         const struct nf_conntrack_tuple_hash *h;
153         const struct nf_conntrack_l4proto *inproto;
154         struct nf_conntrack_zone tmp;
155 
156         NF_CT_ASSERT(skb->nfct == NULL);
157 
158         /* Are they talking about one of our connections? */
159         if (!nf_ct_get_tuplepr(skb,
160                                skb_network_offset(skb)
161                                 + sizeof(struct ipv6hdr)
162                                 + sizeof(struct icmp6hdr),
163                                PF_INET6, net, &origtuple)) {
164                 pr_debug("icmpv6_error: Can't get tuple\n");
165                 return -NF_ACCEPT;
166         }
167 
168         /* rcu_read_lock()ed by nf_hook_slow */
169         inproto = __nf_ct_l4proto_find(PF_INET6, origtuple.dst.protonum);
170 
171         /* Ordinarily, we'd expect the inverted tupleproto, but it's
172            been preserved inside the ICMP. */
173         if (!nf_ct_invert_tuple(&intuple, &origtuple,
174                                 &nf_conntrack_l3proto_ipv6, inproto)) {
175                 pr_debug("icmpv6_error: Can't invert tuple\n");
176                 return -NF_ACCEPT;
177         }
178 
179         *ctinfo = IP_CT_RELATED;
180 
181         h = nf_conntrack_find_get(net, nf_ct_zone_tmpl(tmpl, skb, &tmp),
182                                   &intuple);
183         if (!h) {
184                 pr_debug("icmpv6_error: no match\n");
185                 return -NF_ACCEPT;
186         } else {
187                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
188                         *ctinfo += IP_CT_IS_REPLY;
189         }
190 
191         /* Update skb to refer to this connection */
192         skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
193         skb->nfctinfo = *ctinfo;
194         return NF_ACCEPT;
195 }
196 
197 static int
198 icmpv6_error(struct net *net, struct nf_conn *tmpl,
199              struct sk_buff *skb, unsigned int dataoff,
200              enum ip_conntrack_info *ctinfo, u_int8_t pf, unsigned int hooknum)
201 {
202         const struct icmp6hdr *icmp6h;
203         struct icmp6hdr _ih;
204         int type;
205 
206         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
207         if (icmp6h == NULL) {
208                 if (LOG_INVALID(net, IPPROTO_ICMPV6))
209                         nf_log_packet(net, PF_INET6, 0, skb, NULL, NULL, NULL,
210                               "nf_ct_icmpv6: short packet ");
211                 return -NF_ACCEPT;
212         }
213 
214         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
215             nf_ip6_checksum(skb, hooknum, dataoff, IPPROTO_ICMPV6)) {
216                 if (LOG_INVALID(net, IPPROTO_ICMPV6))
217                         nf_log_packet(net, PF_INET6, 0, skb, NULL, NULL, NULL,
218                                       "nf_ct_icmpv6: ICMPv6 checksum failed ");
219                 return -NF_ACCEPT;
220         }
221 
222         type = icmp6h->icmp6_type - 130;
223         if (type >= 0 && type < sizeof(noct_valid_new) &&
224             noct_valid_new[type]) {
225                 skb->nfct = &nf_ct_untracked_get()->ct_general;
226                 skb->nfctinfo = IP_CT_NEW;
227                 nf_conntrack_get(skb->nfct);
228                 return NF_ACCEPT;
229         }
230 
231         /* is not error message ? */
232         if (icmp6h->icmp6_type >= 128)
233                 return NF_ACCEPT;
234 
235         return icmpv6_error_message(net, tmpl, skb, dataoff, ctinfo, hooknum);
236 }
237 
238 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
239 
240 #include <linux/netfilter/nfnetlink.h>
241 #include <linux/netfilter/nfnetlink_conntrack.h>
242 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
243                                   const struct nf_conntrack_tuple *t)
244 {
245         if (nla_put_be16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id) ||
246             nla_put_u8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type) ||
247             nla_put_u8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code))
248                 goto nla_put_failure;
249         return 0;
250 
251 nla_put_failure:
252         return -1;
253 }
254 
255 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
256         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
257         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
258         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
259 };
260 
261 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
262                                 struct nf_conntrack_tuple *tuple)
263 {
264         if (!tb[CTA_PROTO_ICMPV6_TYPE] ||
265             !tb[CTA_PROTO_ICMPV6_CODE] ||
266             !tb[CTA_PROTO_ICMPV6_ID])
267                 return -EINVAL;
268 
269         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
270         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
271         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
272 
273         if (tuple->dst.u.icmp.type < 128 ||
274             tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
275             !invmap[tuple->dst.u.icmp.type - 128])
276                 return -EINVAL;
277 
278         return 0;
279 }
280 
281 static int icmpv6_nlattr_tuple_size(void)
282 {
283         return nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
284 }
285 #endif
286 
287 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
288 
289 #include <linux/netfilter/nfnetlink.h>
290 #include <linux/netfilter/nfnetlink_cttimeout.h>
291 
292 static int icmpv6_timeout_nlattr_to_obj(struct nlattr *tb[],
293                                         struct net *net, void *data)
294 {
295         unsigned int *timeout = data;
296         struct nf_icmp_net *in = icmpv6_pernet(net);
297 
298         if (tb[CTA_TIMEOUT_ICMPV6_TIMEOUT]) {
299                 *timeout =
300                     ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMPV6_TIMEOUT])) * HZ;
301         } else {
302                 /* Set default ICMPv6 timeout. */
303                 *timeout = in->timeout;
304         }
305         return 0;
306 }
307 
308 static int
309 icmpv6_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
310 {
311         const unsigned int *timeout = data;
312 
313         if (nla_put_be32(skb, CTA_TIMEOUT_ICMPV6_TIMEOUT, htonl(*timeout / HZ)))
314                 goto nla_put_failure;
315         return 0;
316 
317 nla_put_failure:
318         return -ENOSPC;
319 }
320 
321 static const struct nla_policy
322 icmpv6_timeout_nla_policy[CTA_TIMEOUT_ICMPV6_MAX+1] = {
323         [CTA_TIMEOUT_ICMPV6_TIMEOUT]    = { .type = NLA_U32 },
324 };
325 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
326 
327 #ifdef CONFIG_SYSCTL
328 static struct ctl_table icmpv6_sysctl_table[] = {
329         {
330                 .procname       = "nf_conntrack_icmpv6_timeout",
331                 .maxlen         = sizeof(unsigned int),
332                 .mode           = 0644,
333                 .proc_handler   = proc_dointvec_jiffies,
334         },
335         { }
336 };
337 #endif /* CONFIG_SYSCTL */
338 
339 static int icmpv6_kmemdup_sysctl_table(struct nf_proto_net *pn,
340                                        struct nf_icmp_net *in)
341 {
342 #ifdef CONFIG_SYSCTL
343         pn->ctl_table = kmemdup(icmpv6_sysctl_table,
344                                 sizeof(icmpv6_sysctl_table),
345                                 GFP_KERNEL);
346         if (!pn->ctl_table)
347                 return -ENOMEM;
348 
349         pn->ctl_table[0].data = &in->timeout;
350 #endif
351         return 0;
352 }
353 
354 static int icmpv6_init_net(struct net *net, u_int16_t proto)
355 {
356         struct nf_icmp_net *in = icmpv6_pernet(net);
357         struct nf_proto_net *pn = &in->pn;
358 
359         in->timeout = nf_ct_icmpv6_timeout;
360 
361         return icmpv6_kmemdup_sysctl_table(pn, in);
362 }
363 
364 static struct nf_proto_net *icmpv6_get_net_proto(struct net *net)
365 {
366         return &net->ct.nf_ct_proto.icmpv6.pn;
367 }
368 
369 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 __read_mostly =
370 {
371         .l3proto                = PF_INET6,
372         .l4proto                = IPPROTO_ICMPV6,
373         .name                   = "icmpv6",
374         .pkt_to_tuple           = icmpv6_pkt_to_tuple,
375         .invert_tuple           = icmpv6_invert_tuple,
376         .print_tuple            = icmpv6_print_tuple,
377         .packet                 = icmpv6_packet,
378         .get_timeouts           = icmpv6_get_timeouts,
379         .new                    = icmpv6_new,
380         .error                  = icmpv6_error,
381 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
382         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
383         .nlattr_tuple_size      = icmpv6_nlattr_tuple_size,
384         .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
385         .nla_policy             = icmpv6_nla_policy,
386 #endif
387 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
388         .ctnl_timeout           = {
389                 .nlattr_to_obj  = icmpv6_timeout_nlattr_to_obj,
390                 .obj_to_nlattr  = icmpv6_timeout_obj_to_nlattr,
391                 .nlattr_max     = CTA_TIMEOUT_ICMP_MAX,
392                 .obj_size       = sizeof(unsigned int),
393                 .nla_policy     = icmpv6_timeout_nla_policy,
394         },
395 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
396         .init_net               = icmpv6_init_net,
397         .get_net_proto          = icmpv6_get_net_proto,
398 };
399 

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