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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 nf_conntrack_tuple *tuple)
 40 {
 41         const struct icmp6hdr *hp;
 42         struct icmp6hdr _hdr;
 43 
 44         hp = skb_header_pointer(skb, dataoff, sizeof(_hdr), &_hdr);
 45         if (hp == NULL)
 46                 return false;
 47         tuple->dst.u.icmp.type = hp->icmp6_type;
 48         tuple->src.u.icmp.id = hp->icmp6_identifier;
 49         tuple->dst.u.icmp.code = hp->icmp6_code;
 50 
 51         return true;
 52 }
 53 
 54 /* Add 1; spaces filled with 0. */
 55 static const u_int8_t invmap[] = {
 56         [ICMPV6_ECHO_REQUEST - 128]     = ICMPV6_ECHO_REPLY + 1,
 57         [ICMPV6_ECHO_REPLY - 128]       = ICMPV6_ECHO_REQUEST + 1,
 58         [ICMPV6_NI_QUERY - 128]         = ICMPV6_NI_REPLY + 1,
 59         [ICMPV6_NI_REPLY - 128]         = ICMPV6_NI_QUERY +1
 60 };
 61 
 62 static const u_int8_t noct_valid_new[] = {
 63         [ICMPV6_MGM_QUERY - 130] = 1,
 64         [ICMPV6_MGM_REPORT -130] = 1,
 65         [ICMPV6_MGM_REDUCTION - 130] = 1,
 66         [NDISC_ROUTER_SOLICITATION - 130] = 1,
 67         [NDISC_ROUTER_ADVERTISEMENT - 130] = 1,
 68         [NDISC_NEIGHBOUR_SOLICITATION - 130] = 1,
 69         [NDISC_NEIGHBOUR_ADVERTISEMENT - 130] = 1,
 70         [ICMPV6_MLD2_REPORT - 130] = 1
 71 };
 72 
 73 static bool icmpv6_invert_tuple(struct nf_conntrack_tuple *tuple,
 74                                 const struct nf_conntrack_tuple *orig)
 75 {
 76         int type = orig->dst.u.icmp.type - 128;
 77         if (type < 0 || type >= sizeof(invmap) || !invmap[type])
 78                 return false;
 79 
 80         tuple->src.u.icmp.id   = orig->src.u.icmp.id;
 81         tuple->dst.u.icmp.type = invmap[type] - 1;
 82         tuple->dst.u.icmp.code = orig->dst.u.icmp.code;
 83         return true;
 84 }
 85 
 86 /* Print out the per-protocol part of the tuple. */
 87 static int icmpv6_print_tuple(struct seq_file *s,
 88                               const struct nf_conntrack_tuple *tuple)
 89 {
 90         return seq_printf(s, "type=%u code=%u id=%u ",
 91                           tuple->dst.u.icmp.type,
 92                           tuple->dst.u.icmp.code,
 93                           ntohs(tuple->src.u.icmp.id));
 94 }
 95 
 96 static unsigned int *icmpv6_get_timeouts(struct net *net)
 97 {
 98         return &icmpv6_pernet(net)->timeout;
 99 }
100 
101 /* Returns verdict for packet, or -1 for invalid. */
102 static int icmpv6_packet(struct nf_conn *ct,
103                        const struct sk_buff *skb,
104                        unsigned int dataoff,
105                        enum ip_conntrack_info ctinfo,
106                        u_int8_t pf,
107                        unsigned int hooknum,
108                        unsigned int *timeout)
109 {
110         /* Do not immediately delete the connection after the first
111            successful reply to avoid excessive conntrackd traffic
112            and also to handle correctly ICMP echo reply duplicates. */
113         nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
114 
115         return NF_ACCEPT;
116 }
117 
118 /* Called when a new connection for this protocol found. */
119 static bool icmpv6_new(struct nf_conn *ct, const struct sk_buff *skb,
120                        unsigned int dataoff, unsigned int *timeouts)
121 {
122         static const u_int8_t valid_new[] = {
123                 [ICMPV6_ECHO_REQUEST - 128] = 1,
124                 [ICMPV6_NI_QUERY - 128] = 1
125         };
126         int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;
127 
128         if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
129                 /* Can't create a new ICMPv6 `conn' with this. */
130                 pr_debug("icmpv6: can't create new conn with type %u\n",
131                          type + 128);
132                 nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
133                 if (LOG_INVALID(nf_ct_net(ct), IPPROTO_ICMPV6))
134                         nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
135                                       "nf_ct_icmpv6: invalid new with type %d ",
136                                       type + 128);
137                 return false;
138         }
139         return true;
140 }
141 
142 static int
143 icmpv6_error_message(struct net *net, struct nf_conn *tmpl,
144                      struct sk_buff *skb,
145                      unsigned int icmp6off,
146                      enum ip_conntrack_info *ctinfo,
147                      unsigned int hooknum)
148 {
149         struct nf_conntrack_tuple intuple, origtuple;
150         const struct nf_conntrack_tuple_hash *h;
151         const struct nf_conntrack_l4proto *inproto;
152         u16 zone = tmpl ? nf_ct_zone(tmpl) : NF_CT_DEFAULT_ZONE;
153 
154         NF_CT_ASSERT(skb->nfct == NULL);
155 
156         /* Are they talking about one of our connections? */
157         if (!nf_ct_get_tuplepr(skb,
158                                skb_network_offset(skb)
159                                 + sizeof(struct ipv6hdr)
160                                 + sizeof(struct icmp6hdr),
161                                PF_INET6, &origtuple)) {
162                 pr_debug("icmpv6_error: Can't get tuple\n");
163                 return -NF_ACCEPT;
164         }
165 
166         /* rcu_read_lock()ed by nf_hook_slow */
167         inproto = __nf_ct_l4proto_find(PF_INET6, origtuple.dst.protonum);
168 
169         /* Ordinarily, we'd expect the inverted tupleproto, but it's
170            been preserved inside the ICMP. */
171         if (!nf_ct_invert_tuple(&intuple, &origtuple,
172                                 &nf_conntrack_l3proto_ipv6, inproto)) {
173                 pr_debug("icmpv6_error: Can't invert tuple\n");
174                 return -NF_ACCEPT;
175         }
176 
177         *ctinfo = IP_CT_RELATED;
178 
179         h = nf_conntrack_find_get(net, zone, &intuple);
180         if (!h) {
181                 pr_debug("icmpv6_error: no match\n");
182                 return -NF_ACCEPT;
183         } else {
184                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
185                         *ctinfo += IP_CT_IS_REPLY;
186         }
187 
188         /* Update skb to refer to this connection */
189         skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
190         skb->nfctinfo = *ctinfo;
191         return NF_ACCEPT;
192 }
193 
194 static int
195 icmpv6_error(struct net *net, struct nf_conn *tmpl,
196              struct sk_buff *skb, unsigned int dataoff,
197              enum ip_conntrack_info *ctinfo, u_int8_t pf, unsigned int hooknum)
198 {
199         const struct icmp6hdr *icmp6h;
200         struct icmp6hdr _ih;
201         int type;
202 
203         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
204         if (icmp6h == NULL) {
205                 if (LOG_INVALID(net, IPPROTO_ICMPV6))
206                 nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
207                               "nf_ct_icmpv6: short packet ");
208                 return -NF_ACCEPT;
209         }
210 
211         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
212             nf_ip6_checksum(skb, hooknum, dataoff, IPPROTO_ICMPV6)) {
213                 if (LOG_INVALID(net, IPPROTO_ICMPV6))
214                         nf_log_packet(PF_INET6, 0, skb, NULL, NULL, NULL,
215                                       "nf_ct_icmpv6: ICMPv6 checksum failed ");
216                 return -NF_ACCEPT;
217         }
218 
219         type = icmp6h->icmp6_type - 130;
220         if (type >= 0 && type < sizeof(noct_valid_new) &&
221             noct_valid_new[type]) {
222                 skb->nfct = &nf_ct_untracked_get()->ct_general;
223                 skb->nfctinfo = IP_CT_NEW;
224                 nf_conntrack_get(skb->nfct);
225                 return NF_ACCEPT;
226         }
227 
228         /* is not error message ? */
229         if (icmp6h->icmp6_type >= 128)
230                 return NF_ACCEPT;
231 
232         return icmpv6_error_message(net, tmpl, skb, dataoff, ctinfo, hooknum);
233 }
234 
235 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
236 
237 #include <linux/netfilter/nfnetlink.h>
238 #include <linux/netfilter/nfnetlink_conntrack.h>
239 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
240                                   const struct nf_conntrack_tuple *t)
241 {
242         if (nla_put_be16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id) ||
243             nla_put_u8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type) ||
244             nla_put_u8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code))
245                 goto nla_put_failure;
246         return 0;
247 
248 nla_put_failure:
249         return -1;
250 }
251 
252 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
253         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
254         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
255         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
256 };
257 
258 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
259                                 struct nf_conntrack_tuple *tuple)
260 {
261         if (!tb[CTA_PROTO_ICMPV6_TYPE] ||
262             !tb[CTA_PROTO_ICMPV6_CODE] ||
263             !tb[CTA_PROTO_ICMPV6_ID])
264                 return -EINVAL;
265 
266         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
267         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
268         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
269 
270         if (tuple->dst.u.icmp.type < 128 ||
271             tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
272             !invmap[tuple->dst.u.icmp.type - 128])
273                 return -EINVAL;
274 
275         return 0;
276 }
277 
278 static int icmpv6_nlattr_tuple_size(void)
279 {
280         return nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
281 }
282 #endif
283 
284 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
285 
286 #include <linux/netfilter/nfnetlink.h>
287 #include <linux/netfilter/nfnetlink_cttimeout.h>
288 
289 static int icmpv6_timeout_nlattr_to_obj(struct nlattr *tb[],
290                                         struct net *net, void *data)
291 {
292         unsigned int *timeout = data;
293         struct nf_icmp_net *in = icmpv6_pernet(net);
294 
295         if (tb[CTA_TIMEOUT_ICMPV6_TIMEOUT]) {
296                 *timeout =
297                     ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMPV6_TIMEOUT])) * HZ;
298         } else {
299                 /* Set default ICMPv6 timeout. */
300                 *timeout = in->timeout;
301         }
302         return 0;
303 }
304 
305 static int
306 icmpv6_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
307 {
308         const unsigned int *timeout = data;
309 
310         if (nla_put_be32(skb, CTA_TIMEOUT_ICMPV6_TIMEOUT, htonl(*timeout / HZ)))
311                 goto nla_put_failure;
312         return 0;
313 
314 nla_put_failure:
315         return -ENOSPC;
316 }
317 
318 static const struct nla_policy
319 icmpv6_timeout_nla_policy[CTA_TIMEOUT_ICMPV6_MAX+1] = {
320         [CTA_TIMEOUT_ICMPV6_TIMEOUT]    = { .type = NLA_U32 },
321 };
322 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
323 
324 #ifdef CONFIG_SYSCTL
325 static struct ctl_table icmpv6_sysctl_table[] = {
326         {
327                 .procname       = "nf_conntrack_icmpv6_timeout",
328                 .maxlen         = sizeof(unsigned int),
329                 .mode           = 0644,
330                 .proc_handler   = proc_dointvec_jiffies,
331         },
332         { }
333 };
334 #endif /* CONFIG_SYSCTL */
335 
336 static int icmpv6_kmemdup_sysctl_table(struct nf_proto_net *pn,
337                                        struct nf_icmp_net *in)
338 {
339 #ifdef CONFIG_SYSCTL
340         pn->ctl_table = kmemdup(icmpv6_sysctl_table,
341                                 sizeof(icmpv6_sysctl_table),
342                                 GFP_KERNEL);
343         if (!pn->ctl_table)
344                 return -ENOMEM;
345 
346         pn->ctl_table[0].data = &in->timeout;
347 #endif
348         return 0;
349 }
350 
351 static int icmpv6_init_net(struct net *net, u_int16_t proto)
352 {
353         struct nf_icmp_net *in = icmpv6_pernet(net);
354         struct nf_proto_net *pn = &in->pn;
355 
356         in->timeout = nf_ct_icmpv6_timeout;
357 
358         return icmpv6_kmemdup_sysctl_table(pn, in);
359 }
360 
361 static struct nf_proto_net *icmpv6_get_net_proto(struct net *net)
362 {
363         return &net->ct.nf_ct_proto.icmpv6.pn;
364 }
365 
366 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 __read_mostly =
367 {
368         .l3proto                = PF_INET6,
369         .l4proto                = IPPROTO_ICMPV6,
370         .name                   = "icmpv6",
371         .pkt_to_tuple           = icmpv6_pkt_to_tuple,
372         .invert_tuple           = icmpv6_invert_tuple,
373         .print_tuple            = icmpv6_print_tuple,
374         .packet                 = icmpv6_packet,
375         .get_timeouts           = icmpv6_get_timeouts,
376         .new                    = icmpv6_new,
377         .error                  = icmpv6_error,
378 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
379         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
380         .nlattr_tuple_size      = icmpv6_nlattr_tuple_size,
381         .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
382         .nla_policy             = icmpv6_nla_policy,
383 #endif
384 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
385         .ctnl_timeout           = {
386                 .nlattr_to_obj  = icmpv6_timeout_nlattr_to_obj,
387                 .obj_to_nlattr  = icmpv6_timeout_obj_to_nlattr,
388                 .nlattr_max     = CTA_TIMEOUT_ICMP_MAX,
389                 .obj_size       = sizeof(unsigned int),
390                 .nla_policy     = icmpv6_timeout_nla_policy,
391         },
392 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
393         .init_net               = icmpv6_init_net,
394         .get_net_proto          = icmpv6_get_net_proto,
395 };
396 

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