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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 const unsigned int nf_ct_icmpv6_timeout = 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 static unsigned int *icmpv6_get_timeouts(struct net *net)
 88 {
 89         return &icmpv6_pernet(net)->timeout;
 90 }
 91 
 92 /* Returns verdict for packet, or -1 for invalid. */
 93 static int icmpv6_packet(struct nf_conn *ct,
 94                        const struct sk_buff *skb,
 95                        unsigned int dataoff,
 96                        enum ip_conntrack_info ctinfo,
 97                        unsigned int *timeout)
 98 {
 99         /* Do not immediately delete the connection after the first
100            successful reply to avoid excessive conntrackd traffic
101            and also to handle correctly ICMP echo reply duplicates. */
102         nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
103 
104         return NF_ACCEPT;
105 }
106 
107 /* Called when a new connection for this protocol found. */
108 static bool icmpv6_new(struct nf_conn *ct, const struct sk_buff *skb,
109                        unsigned int dataoff, unsigned int *timeouts)
110 {
111         static const u_int8_t valid_new[] = {
112                 [ICMPV6_ECHO_REQUEST - 128] = 1,
113                 [ICMPV6_NI_QUERY - 128] = 1
114         };
115         int type = ct->tuplehash[0].tuple.dst.u.icmp.type - 128;
116 
117         if (type < 0 || type >= sizeof(valid_new) || !valid_new[type]) {
118                 /* Can't create a new ICMPv6 `conn' with this. */
119                 pr_debug("icmpv6: can't create new conn with type %u\n",
120                          type + 128);
121                 nf_ct_dump_tuple_ipv6(&ct->tuplehash[0].tuple);
122                 return false;
123         }
124         return true;
125 }
126 
127 static int
128 icmpv6_error_message(struct net *net, struct nf_conn *tmpl,
129                      struct sk_buff *skb,
130                      unsigned int icmp6off)
131 {
132         struct nf_conntrack_tuple intuple, origtuple;
133         const struct nf_conntrack_tuple_hash *h;
134         const struct nf_conntrack_l4proto *inproto;
135         enum ip_conntrack_info ctinfo;
136         struct nf_conntrack_zone tmp;
137 
138         WARN_ON(skb_nfct(skb));
139 
140         /* Are they talking about one of our connections? */
141         if (!nf_ct_get_tuplepr(skb,
142                                skb_network_offset(skb)
143                                 + sizeof(struct ipv6hdr)
144                                 + sizeof(struct icmp6hdr),
145                                PF_INET6, net, &origtuple)) {
146                 pr_debug("icmpv6_error: Can't get tuple\n");
147                 return -NF_ACCEPT;
148         }
149 
150         /* rcu_read_lock()ed by nf_hook_thresh */
151         inproto = __nf_ct_l4proto_find(PF_INET6, origtuple.dst.protonum);
152 
153         /* Ordinarily, we'd expect the inverted tupleproto, but it's
154            been preserved inside the ICMP. */
155         if (!nf_ct_invert_tuple(&intuple, &origtuple,
156                                 &nf_conntrack_l3proto_ipv6, inproto)) {
157                 pr_debug("icmpv6_error: Can't invert tuple\n");
158                 return -NF_ACCEPT;
159         }
160 
161         ctinfo = IP_CT_RELATED;
162 
163         h = nf_conntrack_find_get(net, nf_ct_zone_tmpl(tmpl, skb, &tmp),
164                                   &intuple);
165         if (!h) {
166                 pr_debug("icmpv6_error: no match\n");
167                 return -NF_ACCEPT;
168         } else {
169                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
170                         ctinfo += IP_CT_IS_REPLY;
171         }
172 
173         /* Update skb to refer to this connection */
174         nf_ct_set(skb, nf_ct_tuplehash_to_ctrack(h), ctinfo);
175         return NF_ACCEPT;
176 }
177 
178 static void icmpv6_error_log(const struct sk_buff *skb, struct net *net,
179                              u8 pf, const char *msg)
180 {
181         nf_l4proto_log_invalid(skb, net, pf, IPPROTO_ICMPV6, "%s", msg);
182 }
183 
184 static int
185 icmpv6_error(struct net *net, struct nf_conn *tmpl,
186              struct sk_buff *skb, unsigned int dataoff,
187              u8 pf, unsigned int hooknum)
188 {
189         const struct icmp6hdr *icmp6h;
190         struct icmp6hdr _ih;
191         int type;
192 
193         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
194         if (icmp6h == NULL) {
195                 icmpv6_error_log(skb, net, pf, "short packet");
196                 return -NF_ACCEPT;
197         }
198 
199         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
200             nf_ip6_checksum(skb, hooknum, dataoff, IPPROTO_ICMPV6)) {
201                 icmpv6_error_log(skb, net, pf, "ICMPv6 checksum failed");
202                 return -NF_ACCEPT;
203         }
204 
205         type = icmp6h->icmp6_type - 130;
206         if (type >= 0 && type < sizeof(noct_valid_new) &&
207             noct_valid_new[type]) {
208                 nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
209                 return NF_ACCEPT;
210         }
211 
212         /* is not error message ? */
213         if (icmp6h->icmp6_type >= 128)
214                 return NF_ACCEPT;
215 
216         return icmpv6_error_message(net, tmpl, skb, dataoff);
217 }
218 
219 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
220 
221 #include <linux/netfilter/nfnetlink.h>
222 #include <linux/netfilter/nfnetlink_conntrack.h>
223 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
224                                   const struct nf_conntrack_tuple *t)
225 {
226         if (nla_put_be16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id) ||
227             nla_put_u8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type) ||
228             nla_put_u8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code))
229                 goto nla_put_failure;
230         return 0;
231 
232 nla_put_failure:
233         return -1;
234 }
235 
236 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
237         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
238         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
239         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
240 };
241 
242 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
243                                 struct nf_conntrack_tuple *tuple)
244 {
245         if (!tb[CTA_PROTO_ICMPV6_TYPE] ||
246             !tb[CTA_PROTO_ICMPV6_CODE] ||
247             !tb[CTA_PROTO_ICMPV6_ID])
248                 return -EINVAL;
249 
250         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
251         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
252         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
253 
254         if (tuple->dst.u.icmp.type < 128 ||
255             tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
256             !invmap[tuple->dst.u.icmp.type - 128])
257                 return -EINVAL;
258 
259         return 0;
260 }
261 
262 static unsigned int icmpv6_nlattr_tuple_size(void)
263 {
264         static unsigned int size __read_mostly;
265 
266         if (!size)
267                 size = nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
268 
269         return size;
270 }
271 #endif
272 
273 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
274 
275 #include <linux/netfilter/nfnetlink.h>
276 #include <linux/netfilter/nfnetlink_cttimeout.h>
277 
278 static int icmpv6_timeout_nlattr_to_obj(struct nlattr *tb[],
279                                         struct net *net, void *data)
280 {
281         unsigned int *timeout = data;
282         struct nf_icmp_net *in = icmpv6_pernet(net);
283 
284         if (tb[CTA_TIMEOUT_ICMPV6_TIMEOUT]) {
285                 *timeout =
286                     ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMPV6_TIMEOUT])) * HZ;
287         } else {
288                 /* Set default ICMPv6 timeout. */
289                 *timeout = in->timeout;
290         }
291         return 0;
292 }
293 
294 static int
295 icmpv6_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
296 {
297         const unsigned int *timeout = data;
298 
299         if (nla_put_be32(skb, CTA_TIMEOUT_ICMPV6_TIMEOUT, htonl(*timeout / HZ)))
300                 goto nla_put_failure;
301         return 0;
302 
303 nla_put_failure:
304         return -ENOSPC;
305 }
306 
307 static const struct nla_policy
308 icmpv6_timeout_nla_policy[CTA_TIMEOUT_ICMPV6_MAX+1] = {
309         [CTA_TIMEOUT_ICMPV6_TIMEOUT]    = { .type = NLA_U32 },
310 };
311 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
312 
313 #ifdef CONFIG_SYSCTL
314 static struct ctl_table icmpv6_sysctl_table[] = {
315         {
316                 .procname       = "nf_conntrack_icmpv6_timeout",
317                 .maxlen         = sizeof(unsigned int),
318                 .mode           = 0644,
319                 .proc_handler   = proc_dointvec_jiffies,
320         },
321         { }
322 };
323 #endif /* CONFIG_SYSCTL */
324 
325 static int icmpv6_kmemdup_sysctl_table(struct nf_proto_net *pn,
326                                        struct nf_icmp_net *in)
327 {
328 #ifdef CONFIG_SYSCTL
329         pn->ctl_table = kmemdup(icmpv6_sysctl_table,
330                                 sizeof(icmpv6_sysctl_table),
331                                 GFP_KERNEL);
332         if (!pn->ctl_table)
333                 return -ENOMEM;
334 
335         pn->ctl_table[0].data = &in->timeout;
336 #endif
337         return 0;
338 }
339 
340 static int icmpv6_init_net(struct net *net, u_int16_t proto)
341 {
342         struct nf_icmp_net *in = icmpv6_pernet(net);
343         struct nf_proto_net *pn = &in->pn;
344 
345         in->timeout = nf_ct_icmpv6_timeout;
346 
347         return icmpv6_kmemdup_sysctl_table(pn, in);
348 }
349 
350 static struct nf_proto_net *icmpv6_get_net_proto(struct net *net)
351 {
352         return &net->ct.nf_ct_proto.icmpv6.pn;
353 }
354 
355 const struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 =
356 {
357         .l3proto                = PF_INET6,
358         .l4proto                = IPPROTO_ICMPV6,
359         .pkt_to_tuple           = icmpv6_pkt_to_tuple,
360         .invert_tuple           = icmpv6_invert_tuple,
361         .packet                 = icmpv6_packet,
362         .get_timeouts           = icmpv6_get_timeouts,
363         .new                    = icmpv6_new,
364         .error                  = icmpv6_error,
365 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
366         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
367         .nlattr_tuple_size      = icmpv6_nlattr_tuple_size,
368         .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
369         .nla_policy             = icmpv6_nla_policy,
370 #endif
371 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
372         .ctnl_timeout           = {
373                 .nlattr_to_obj  = icmpv6_timeout_nlattr_to_obj,
374                 .obj_to_nlattr  = icmpv6_timeout_obj_to_nlattr,
375                 .nlattr_max     = CTA_TIMEOUT_ICMP_MAX,
376                 .obj_size       = sizeof(unsigned int),
377                 .nla_policy     = icmpv6_timeout_nla_policy,
378         },
379 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
380         .init_net               = icmpv6_init_net,
381         .get_net_proto          = icmpv6_get_net_proto,
382 };
383 

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