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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 void icmpv6_print_tuple(struct seq_file *s,
 88                               const struct nf_conntrack_tuple *tuple)
 89 {
 90         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(nf_ct_net(ct), PF_INET6, 0, skb, NULL,
135                                       NULL, NULL,
136                                       "nf_ct_icmpv6: invalid new with type %d ",
137                                       type + 128);
138                 return false;
139         }
140         return true;
141 }
142 
143 static int
144 icmpv6_error_message(struct net *net, struct nf_conn *tmpl,
145                      struct sk_buff *skb,
146                      unsigned int icmp6off,
147                      enum ip_conntrack_info *ctinfo,
148                      unsigned int hooknum)
149 {
150         struct nf_conntrack_tuple intuple, origtuple;
151         const struct nf_conntrack_tuple_hash *h;
152         const struct nf_conntrack_l4proto *inproto;
153         u16 zone = tmpl ? nf_ct_zone(tmpl) : NF_CT_DEFAULT_ZONE;
154 
155         NF_CT_ASSERT(skb->nfct == NULL);
156 
157         /* Are they talking about one of our connections? */
158         if (!nf_ct_get_tuplepr(skb,
159                                skb_network_offset(skb)
160                                 + sizeof(struct ipv6hdr)
161                                 + sizeof(struct icmp6hdr),
162                                PF_INET6, &origtuple)) {
163                 pr_debug("icmpv6_error: Can't get tuple\n");
164                 return -NF_ACCEPT;
165         }
166 
167         /* rcu_read_lock()ed by nf_hook_slow */
168         inproto = __nf_ct_l4proto_find(PF_INET6, origtuple.dst.protonum);
169 
170         /* Ordinarily, we'd expect the inverted tupleproto, but it's
171            been preserved inside the ICMP. */
172         if (!nf_ct_invert_tuple(&intuple, &origtuple,
173                                 &nf_conntrack_l3proto_ipv6, inproto)) {
174                 pr_debug("icmpv6_error: Can't invert tuple\n");
175                 return -NF_ACCEPT;
176         }
177 
178         *ctinfo = IP_CT_RELATED;
179 
180         h = nf_conntrack_find_get(net, zone, &intuple);
181         if (!h) {
182                 pr_debug("icmpv6_error: no match\n");
183                 return -NF_ACCEPT;
184         } else {
185                 if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY)
186                         *ctinfo += IP_CT_IS_REPLY;
187         }
188 
189         /* Update skb to refer to this connection */
190         skb->nfct = &nf_ct_tuplehash_to_ctrack(h)->ct_general;
191         skb->nfctinfo = *ctinfo;
192         return NF_ACCEPT;
193 }
194 
195 static int
196 icmpv6_error(struct net *net, struct nf_conn *tmpl,
197              struct sk_buff *skb, unsigned int dataoff,
198              enum ip_conntrack_info *ctinfo, u_int8_t pf, unsigned int hooknum)
199 {
200         const struct icmp6hdr *icmp6h;
201         struct icmp6hdr _ih;
202         int type;
203 
204         icmp6h = skb_header_pointer(skb, dataoff, sizeof(_ih), &_ih);
205         if (icmp6h == NULL) {
206                 if (LOG_INVALID(net, IPPROTO_ICMPV6))
207                         nf_log_packet(net, PF_INET6, 0, skb, NULL, NULL, NULL,
208                               "nf_ct_icmpv6: short packet ");
209                 return -NF_ACCEPT;
210         }
211 
212         if (net->ct.sysctl_checksum && hooknum == NF_INET_PRE_ROUTING &&
213             nf_ip6_checksum(skb, hooknum, dataoff, IPPROTO_ICMPV6)) {
214                 if (LOG_INVALID(net, IPPROTO_ICMPV6))
215                         nf_log_packet(net, PF_INET6, 0, skb, NULL, NULL, NULL,
216                                       "nf_ct_icmpv6: ICMPv6 checksum failed ");
217                 return -NF_ACCEPT;
218         }
219 
220         type = icmp6h->icmp6_type - 130;
221         if (type >= 0 && type < sizeof(noct_valid_new) &&
222             noct_valid_new[type]) {
223                 skb->nfct = &nf_ct_untracked_get()->ct_general;
224                 skb->nfctinfo = IP_CT_NEW;
225                 nf_conntrack_get(skb->nfct);
226                 return NF_ACCEPT;
227         }
228 
229         /* is not error message ? */
230         if (icmp6h->icmp6_type >= 128)
231                 return NF_ACCEPT;
232 
233         return icmpv6_error_message(net, tmpl, skb, dataoff, ctinfo, hooknum);
234 }
235 
236 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
237 
238 #include <linux/netfilter/nfnetlink.h>
239 #include <linux/netfilter/nfnetlink_conntrack.h>
240 static int icmpv6_tuple_to_nlattr(struct sk_buff *skb,
241                                   const struct nf_conntrack_tuple *t)
242 {
243         if (nla_put_be16(skb, CTA_PROTO_ICMPV6_ID, t->src.u.icmp.id) ||
244             nla_put_u8(skb, CTA_PROTO_ICMPV6_TYPE, t->dst.u.icmp.type) ||
245             nla_put_u8(skb, CTA_PROTO_ICMPV6_CODE, t->dst.u.icmp.code))
246                 goto nla_put_failure;
247         return 0;
248 
249 nla_put_failure:
250         return -1;
251 }
252 
253 static const struct nla_policy icmpv6_nla_policy[CTA_PROTO_MAX+1] = {
254         [CTA_PROTO_ICMPV6_TYPE] = { .type = NLA_U8 },
255         [CTA_PROTO_ICMPV6_CODE] = { .type = NLA_U8 },
256         [CTA_PROTO_ICMPV6_ID]   = { .type = NLA_U16 },
257 };
258 
259 static int icmpv6_nlattr_to_tuple(struct nlattr *tb[],
260                                 struct nf_conntrack_tuple *tuple)
261 {
262         if (!tb[CTA_PROTO_ICMPV6_TYPE] ||
263             !tb[CTA_PROTO_ICMPV6_CODE] ||
264             !tb[CTA_PROTO_ICMPV6_ID])
265                 return -EINVAL;
266 
267         tuple->dst.u.icmp.type = nla_get_u8(tb[CTA_PROTO_ICMPV6_TYPE]);
268         tuple->dst.u.icmp.code = nla_get_u8(tb[CTA_PROTO_ICMPV6_CODE]);
269         tuple->src.u.icmp.id = nla_get_be16(tb[CTA_PROTO_ICMPV6_ID]);
270 
271         if (tuple->dst.u.icmp.type < 128 ||
272             tuple->dst.u.icmp.type - 128 >= sizeof(invmap) ||
273             !invmap[tuple->dst.u.icmp.type - 128])
274                 return -EINVAL;
275 
276         return 0;
277 }
278 
279 static int icmpv6_nlattr_tuple_size(void)
280 {
281         return nla_policy_len(icmpv6_nla_policy, CTA_PROTO_MAX + 1);
282 }
283 #endif
284 
285 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
286 
287 #include <linux/netfilter/nfnetlink.h>
288 #include <linux/netfilter/nfnetlink_cttimeout.h>
289 
290 static int icmpv6_timeout_nlattr_to_obj(struct nlattr *tb[],
291                                         struct net *net, void *data)
292 {
293         unsigned int *timeout = data;
294         struct nf_icmp_net *in = icmpv6_pernet(net);
295 
296         if (tb[CTA_TIMEOUT_ICMPV6_TIMEOUT]) {
297                 *timeout =
298                     ntohl(nla_get_be32(tb[CTA_TIMEOUT_ICMPV6_TIMEOUT])) * HZ;
299         } else {
300                 /* Set default ICMPv6 timeout. */
301                 *timeout = in->timeout;
302         }
303         return 0;
304 }
305 
306 static int
307 icmpv6_timeout_obj_to_nlattr(struct sk_buff *skb, const void *data)
308 {
309         const unsigned int *timeout = data;
310 
311         if (nla_put_be32(skb, CTA_TIMEOUT_ICMPV6_TIMEOUT, htonl(*timeout / HZ)))
312                 goto nla_put_failure;
313         return 0;
314 
315 nla_put_failure:
316         return -ENOSPC;
317 }
318 
319 static const struct nla_policy
320 icmpv6_timeout_nla_policy[CTA_TIMEOUT_ICMPV6_MAX+1] = {
321         [CTA_TIMEOUT_ICMPV6_TIMEOUT]    = { .type = NLA_U32 },
322 };
323 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
324 
325 #ifdef CONFIG_SYSCTL
326 static struct ctl_table icmpv6_sysctl_table[] = {
327         {
328                 .procname       = "nf_conntrack_icmpv6_timeout",
329                 .maxlen         = sizeof(unsigned int),
330                 .mode           = 0644,
331                 .proc_handler   = proc_dointvec_jiffies,
332         },
333         { }
334 };
335 #endif /* CONFIG_SYSCTL */
336 
337 static int icmpv6_kmemdup_sysctl_table(struct nf_proto_net *pn,
338                                        struct nf_icmp_net *in)
339 {
340 #ifdef CONFIG_SYSCTL
341         pn->ctl_table = kmemdup(icmpv6_sysctl_table,
342                                 sizeof(icmpv6_sysctl_table),
343                                 GFP_KERNEL);
344         if (!pn->ctl_table)
345                 return -ENOMEM;
346 
347         pn->ctl_table[0].data = &in->timeout;
348 #endif
349         return 0;
350 }
351 
352 static int icmpv6_init_net(struct net *net, u_int16_t proto)
353 {
354         struct nf_icmp_net *in = icmpv6_pernet(net);
355         struct nf_proto_net *pn = &in->pn;
356 
357         in->timeout = nf_ct_icmpv6_timeout;
358 
359         return icmpv6_kmemdup_sysctl_table(pn, in);
360 }
361 
362 static struct nf_proto_net *icmpv6_get_net_proto(struct net *net)
363 {
364         return &net->ct.nf_ct_proto.icmpv6.pn;
365 }
366 
367 struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 __read_mostly =
368 {
369         .l3proto                = PF_INET6,
370         .l4proto                = IPPROTO_ICMPV6,
371         .name                   = "icmpv6",
372         .pkt_to_tuple           = icmpv6_pkt_to_tuple,
373         .invert_tuple           = icmpv6_invert_tuple,
374         .print_tuple            = icmpv6_print_tuple,
375         .packet                 = icmpv6_packet,
376         .get_timeouts           = icmpv6_get_timeouts,
377         .new                    = icmpv6_new,
378         .error                  = icmpv6_error,
379 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
380         .tuple_to_nlattr        = icmpv6_tuple_to_nlattr,
381         .nlattr_tuple_size      = icmpv6_nlattr_tuple_size,
382         .nlattr_to_tuple        = icmpv6_nlattr_to_tuple,
383         .nla_policy             = icmpv6_nla_policy,
384 #endif
385 #if IS_ENABLED(CONFIG_NF_CT_NETLINK_TIMEOUT)
386         .ctnl_timeout           = {
387                 .nlattr_to_obj  = icmpv6_timeout_nlattr_to_obj,
388                 .obj_to_nlattr  = icmpv6_timeout_obj_to_nlattr,
389                 .nlattr_max     = CTA_TIMEOUT_ICMP_MAX,
390                 .obj_size       = sizeof(unsigned int),
391                 .nla_policy     = icmpv6_timeout_nla_policy,
392         },
393 #endif /* CONFIG_NF_CT_NETLINK_TIMEOUT */
394         .init_net               = icmpv6_init_net,
395         .get_net_proto          = icmpv6_get_net_proto,
396 };
397 

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