1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Connection state tracking for netfilter.  This is separated from,
3    but required by, the NAT layer; it can also be used by an iptables
4    extension. */
5 
6 /* (C) 1999-2001 Paul `Rusty' Russell
7  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
8  * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
9  * (C) 2005-2012 Patrick McHardy <kaber@trash.net>
10  */
11 
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 
14 #include <linux/types.h>
15 #include <linux/netfilter.h>
16 #include <linux/module.h>
17 #include <linux/sched.h>
18 #include <linux/skbuff.h>
19 #include <linux/proc_fs.h>
20 #include <linux/vmalloc.h>
21 #include <linux/stddef.h>
22 #include <linux/slab.h>
23 #include <linux/random.h>
24 #include <linux/siphash.h>
25 #include <linux/err.h>
26 #include <linux/percpu.h>
27 #include <linux/moduleparam.h>
28 #include <linux/notifier.h>
29 #include <linux/kernel.h>
30 #include <linux/netdevice.h>
31 #include <linux/socket.h>
32 #include <linux/mm.h>
33 #include <linux/nsproxy.h>
34 #include <linux/rculist_nulls.h>
35 
36 #include <net/netfilter/nf_conntrack.h>
37 #include <net/netfilter/nf_conntrack_bpf.h>
38 #include <net/netfilter/nf_conntrack_l4proto.h>
39 #include <net/netfilter/nf_conntrack_expect.h>
40 #include <net/netfilter/nf_conntrack_helper.h>
41 #include <net/netfilter/nf_conntrack_core.h>
42 #include <net/netfilter/nf_conntrack_extend.h>
43 #include <net/netfilter/nf_conntrack_acct.h>
44 #include <net/netfilter/nf_conntrack_ecache.h>
45 #include <net/netfilter/nf_conntrack_zones.h>
46 #include <net/netfilter/nf_conntrack_timestamp.h>
47 #include <net/netfilter/nf_conntrack_timeout.h>
48 #include <net/netfilter/nf_conntrack_labels.h>
49 #include <net/netfilter/nf_conntrack_synproxy.h>
50 #include <net/netfilter/nf_nat.h>
51 #include <net/netfilter/nf_nat_helper.h>
52 #include <net/netns/hash.h>
53 #include <net/ip.h>
54 
55 #include "nf_internals.h"
56 
57 __cacheline_aligned_in_smp spinlock_t nf_conntrack_locks[CONNTRACK_LOCKS];
58 EXPORT_SYMBOL_GPL(nf_conntrack_locks);
59 
60 __cacheline_aligned_in_smp DEFINE_SPINLOCK(nf_conntrack_expect_lock);
61 EXPORT_SYMBOL_GPL(nf_conntrack_expect_lock);
62 
63 struct hlist_nulls_head *nf_conntrack_hash __read_mostly;
64 EXPORT_SYMBOL_GPL(nf_conntrack_hash);
65 
66 struct conntrack_gc_work {
67 	struct delayed_work	dwork;
68 	u32			next_bucket;
69 	u32			avg_timeout;
70 	u32			count;
71 	u32			start_time;
72 	bool			exiting;
73 	bool			early_drop;
74 };
75 
76 static __read_mostly struct kmem_cache *nf_conntrack_cachep;
77 static DEFINE_SPINLOCK(nf_conntrack_locks_all_lock);
78 static __read_mostly bool nf_conntrack_locks_all;
79 
80 /* serialize hash resizes and nf_ct_iterate_cleanup */
81 static DEFINE_MUTEX(nf_conntrack_mutex);
82 
83 #define GC_SCAN_INTERVAL_MAX	(60ul * HZ)
84 #define GC_SCAN_INTERVAL_MIN	(1ul * HZ)
85 
86 /* clamp timeouts to this value (TCP unacked) */
87 #define GC_SCAN_INTERVAL_CLAMP	(300ul * HZ)
88 
89 /* Initial bias pretending we have 100 entries at the upper bound so we don't
90  * wakeup often just because we have three entries with a 1s timeout while still
91  * allowing non-idle machines to wakeup more often when needed.
92  */
93 #define GC_SCAN_INITIAL_COUNT	100
94 #define GC_SCAN_INTERVAL_INIT	GC_SCAN_INTERVAL_MAX
95 
96 #define GC_SCAN_MAX_DURATION	msecs_to_jiffies(10)
97 #define GC_SCAN_EXPIRED_MAX	(64000u / HZ)
98 
99 #define MIN_CHAINLEN	8u
100 #define MAX_CHAINLEN	(32u - MIN_CHAINLEN)
101 
102 static struct conntrack_gc_work conntrack_gc_work;
103 
nf_conntrack_lock(spinlock_t * lock)104 void nf_conntrack_lock(spinlock_t *lock) __acquires(lock)
105 {
106 	/* 1) Acquire the lock */
107 	spin_lock(lock);
108 
109 	/* 2) read nf_conntrack_locks_all, with ACQUIRE semantics
110 	 * It pairs with the smp_store_release() in nf_conntrack_all_unlock()
111 	 */
112 	if (likely(smp_load_acquire(&nf_conntrack_locks_all) == false))
113 		return;
114 
115 	/* fast path failed, unlock */
116 	spin_unlock(lock);
117 
118 	/* Slow path 1) get global lock */
119 	spin_lock(&nf_conntrack_locks_all_lock);
120 
121 	/* Slow path 2) get the lock we want */
122 	spin_lock(lock);
123 
124 	/* Slow path 3) release the global lock */
125 	spin_unlock(&nf_conntrack_locks_all_lock);
126 }
127 EXPORT_SYMBOL_GPL(nf_conntrack_lock);
128 
nf_conntrack_double_unlock(unsigned int h1,unsigned int h2)129 static void nf_conntrack_double_unlock(unsigned int h1, unsigned int h2)
130 {
131 	h1 %= CONNTRACK_LOCKS;
132 	h2 %= CONNTRACK_LOCKS;
133 	spin_unlock(&nf_conntrack_locks[h1]);
134 	if (h1 != h2)
135 		spin_unlock(&nf_conntrack_locks[h2]);
136 }
137 
138 /* return true if we need to recompute hashes (in case hash table was resized) */
nf_conntrack_double_lock(struct net * net,unsigned int h1,unsigned int h2,unsigned int sequence)139 static bool nf_conntrack_double_lock(struct net *net, unsigned int h1,
140 				     unsigned int h2, unsigned int sequence)
141 {
142 	h1 %= CONNTRACK_LOCKS;
143 	h2 %= CONNTRACK_LOCKS;
144 	if (h1 <= h2) {
145 		nf_conntrack_lock(&nf_conntrack_locks[h1]);
146 		if (h1 != h2)
147 			spin_lock_nested(&nf_conntrack_locks[h2],
148 					 SINGLE_DEPTH_NESTING);
149 	} else {
150 		nf_conntrack_lock(&nf_conntrack_locks[h2]);
151 		spin_lock_nested(&nf_conntrack_locks[h1],
152 				 SINGLE_DEPTH_NESTING);
153 	}
154 	if (read_seqcount_retry(&nf_conntrack_generation, sequence)) {
155 		nf_conntrack_double_unlock(h1, h2);
156 		return true;
157 	}
158 	return false;
159 }
160 
nf_conntrack_all_lock(void)161 static void nf_conntrack_all_lock(void)
162 	__acquires(&nf_conntrack_locks_all_lock)
163 {
164 	int i;
165 
166 	spin_lock(&nf_conntrack_locks_all_lock);
167 
168 	/* For nf_contrack_locks_all, only the latest time when another
169 	 * CPU will see an update is controlled, by the "release" of the
170 	 * spin_lock below.
171 	 * The earliest time is not controlled, an thus KCSAN could detect
172 	 * a race when nf_conntract_lock() reads the variable.
173 	 * WRITE_ONCE() is used to ensure the compiler will not
174 	 * optimize the write.
175 	 */
176 	WRITE_ONCE(nf_conntrack_locks_all, true);
177 
178 	for (i = 0; i < CONNTRACK_LOCKS; i++) {
179 		spin_lock(&nf_conntrack_locks[i]);
180 
181 		/* This spin_unlock provides the "release" to ensure that
182 		 * nf_conntrack_locks_all==true is visible to everyone that
183 		 * acquired spin_lock(&nf_conntrack_locks[]).
184 		 */
185 		spin_unlock(&nf_conntrack_locks[i]);
186 	}
187 }
188 
nf_conntrack_all_unlock(void)189 static void nf_conntrack_all_unlock(void)
190 	__releases(&nf_conntrack_locks_all_lock)
191 {
192 	/* All prior stores must be complete before we clear
193 	 * 'nf_conntrack_locks_all'. Otherwise nf_conntrack_lock()
194 	 * might observe the false value but not the entire
195 	 * critical section.
196 	 * It pairs with the smp_load_acquire() in nf_conntrack_lock()
197 	 */
198 	smp_store_release(&nf_conntrack_locks_all, false);
199 	spin_unlock(&nf_conntrack_locks_all_lock);
200 }
201 
202 unsigned int nf_conntrack_htable_size __read_mostly;
203 EXPORT_SYMBOL_GPL(nf_conntrack_htable_size);
204 
205 unsigned int nf_conntrack_max __read_mostly;
206 EXPORT_SYMBOL_GPL(nf_conntrack_max);
207 seqcount_spinlock_t nf_conntrack_generation __read_mostly;
208 static siphash_aligned_key_t nf_conntrack_hash_rnd;
209 
hash_conntrack_raw(const struct nf_conntrack_tuple * tuple,unsigned int zoneid,const struct net * net)210 static u32 hash_conntrack_raw(const struct nf_conntrack_tuple *tuple,
211 			      unsigned int zoneid,
212 			      const struct net *net)
213 {
214 	struct {
215 		struct nf_conntrack_man src;
216 		union nf_inet_addr dst_addr;
217 		unsigned int zone;
218 		u32 net_mix;
219 		u16 dport;
220 		u16 proto;
221 	} __aligned(SIPHASH_ALIGNMENT) combined;
222 
223 	get_random_once(&nf_conntrack_hash_rnd, sizeof(nf_conntrack_hash_rnd));
224 
225 	memset(&combined, 0, sizeof(combined));
226 
227 	/* The direction must be ignored, so handle usable members manually. */
228 	combined.src = tuple->src;
229 	combined.dst_addr = tuple->dst.u3;
230 	combined.zone = zoneid;
231 	combined.net_mix = net_hash_mix(net);
232 	combined.dport = (__force __u16)tuple->dst.u.all;
233 	combined.proto = tuple->dst.protonum;
234 
235 	return (u32)siphash(&combined, sizeof(combined), &nf_conntrack_hash_rnd);
236 }
237 
scale_hash(u32 hash)238 static u32 scale_hash(u32 hash)
239 {
240 	return reciprocal_scale(hash, nf_conntrack_htable_size);
241 }
242 
__hash_conntrack(const struct net * net,const struct nf_conntrack_tuple * tuple,unsigned int zoneid,unsigned int size)243 static u32 __hash_conntrack(const struct net *net,
244 			    const struct nf_conntrack_tuple *tuple,
245 			    unsigned int zoneid,
246 			    unsigned int size)
247 {
248 	return reciprocal_scale(hash_conntrack_raw(tuple, zoneid, net), size);
249 }
250 
hash_conntrack(const struct net * net,const struct nf_conntrack_tuple * tuple,unsigned int zoneid)251 static u32 hash_conntrack(const struct net *net,
252 			  const struct nf_conntrack_tuple *tuple,
253 			  unsigned int zoneid)
254 {
255 	return scale_hash(hash_conntrack_raw(tuple, zoneid, net));
256 }
257 
nf_ct_get_tuple_ports(const struct sk_buff * skb,unsigned int dataoff,struct nf_conntrack_tuple * tuple)258 static bool nf_ct_get_tuple_ports(const struct sk_buff *skb,
259 				  unsigned int dataoff,
260 				  struct nf_conntrack_tuple *tuple)
261 {	struct {
262 		__be16 sport;
263 		__be16 dport;
264 	} _inet_hdr, *inet_hdr;
265 
266 	/* Actually only need first 4 bytes to get ports. */
267 	inet_hdr = skb_header_pointer(skb, dataoff, sizeof(_inet_hdr), &_inet_hdr);
268 	if (!inet_hdr)
269 		return false;
270 
271 	tuple->src.u.udp.port = inet_hdr->sport;
272 	tuple->dst.u.udp.port = inet_hdr->dport;
273 	return true;
274 }
275 
276 static bool
nf_ct_get_tuple(const struct sk_buff * skb,unsigned int nhoff,unsigned int dataoff,u_int16_t l3num,u_int8_t protonum,struct net * net,struct nf_conntrack_tuple * tuple)277 nf_ct_get_tuple(const struct sk_buff *skb,
278 		unsigned int nhoff,
279 		unsigned int dataoff,
280 		u_int16_t l3num,
281 		u_int8_t protonum,
282 		struct net *net,
283 		struct nf_conntrack_tuple *tuple)
284 {
285 	unsigned int size;
286 	const __be32 *ap;
287 	__be32 _addrs[8];
288 
289 	memset(tuple, 0, sizeof(*tuple));
290 
291 	tuple->src.l3num = l3num;
292 	switch (l3num) {
293 	case NFPROTO_IPV4:
294 		nhoff += offsetof(struct iphdr, saddr);
295 		size = 2 * sizeof(__be32);
296 		break;
297 	case NFPROTO_IPV6:
298 		nhoff += offsetof(struct ipv6hdr, saddr);
299 		size = sizeof(_addrs);
300 		break;
301 	default:
302 		return true;
303 	}
304 
305 	ap = skb_header_pointer(skb, nhoff, size, _addrs);
306 	if (!ap)
307 		return false;
308 
309 	switch (l3num) {
310 	case NFPROTO_IPV4:
311 		tuple->src.u3.ip = ap[0];
312 		tuple->dst.u3.ip = ap[1];
313 		break;
314 	case NFPROTO_IPV6:
315 		memcpy(tuple->src.u3.ip6, ap, sizeof(tuple->src.u3.ip6));
316 		memcpy(tuple->dst.u3.ip6, ap + 4, sizeof(tuple->dst.u3.ip6));
317 		break;
318 	}
319 
320 	tuple->dst.protonum = protonum;
321 	tuple->dst.dir = IP_CT_DIR_ORIGINAL;
322 
323 	switch (protonum) {
324 #if IS_ENABLED(CONFIG_IPV6)
325 	case IPPROTO_ICMPV6:
326 		return icmpv6_pkt_to_tuple(skb, dataoff, net, tuple);
327 #endif
328 	case IPPROTO_ICMP:
329 		return icmp_pkt_to_tuple(skb, dataoff, net, tuple);
330 #ifdef CONFIG_NF_CT_PROTO_GRE
331 	case IPPROTO_GRE:
332 		return gre_pkt_to_tuple(skb, dataoff, net, tuple);
333 #endif
334 	case IPPROTO_TCP:
335 	case IPPROTO_UDP:
336 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
337 	case IPPROTO_UDPLITE:
338 #endif
339 #ifdef CONFIG_NF_CT_PROTO_SCTP
340 	case IPPROTO_SCTP:
341 #endif
342 #ifdef CONFIG_NF_CT_PROTO_DCCP
343 	case IPPROTO_DCCP:
344 #endif
345 		/* fallthrough */
346 		return nf_ct_get_tuple_ports(skb, dataoff, tuple);
347 	default:
348 		break;
349 	}
350 
351 	return true;
352 }
353 
ipv4_get_l4proto(const struct sk_buff * skb,unsigned int nhoff,u_int8_t * protonum)354 static int ipv4_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
355 			    u_int8_t *protonum)
356 {
357 	int dataoff = -1;
358 	const struct iphdr *iph;
359 	struct iphdr _iph;
360 
361 	iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
362 	if (!iph)
363 		return -1;
364 
365 	/* Conntrack defragments packets, we might still see fragments
366 	 * inside ICMP packets though.
367 	 */
368 	if (iph->frag_off & htons(IP_OFFSET))
369 		return -1;
370 
371 	dataoff = nhoff + (iph->ihl << 2);
372 	*protonum = iph->protocol;
373 
374 	/* Check bogus IP headers */
375 	if (dataoff > skb->len) {
376 		pr_debug("bogus IPv4 packet: nhoff %u, ihl %u, skblen %u\n",
377 			 nhoff, iph->ihl << 2, skb->len);
378 		return -1;
379 	}
380 	return dataoff;
381 }
382 
383 #if IS_ENABLED(CONFIG_IPV6)
ipv6_get_l4proto(const struct sk_buff * skb,unsigned int nhoff,u8 * protonum)384 static int ipv6_get_l4proto(const struct sk_buff *skb, unsigned int nhoff,
385 			    u8 *protonum)
386 {
387 	int protoff = -1;
388 	unsigned int extoff = nhoff + sizeof(struct ipv6hdr);
389 	__be16 frag_off;
390 	u8 nexthdr;
391 
392 	if (skb_copy_bits(skb, nhoff + offsetof(struct ipv6hdr, nexthdr),
393 			  &nexthdr, sizeof(nexthdr)) != 0) {
394 		pr_debug("can't get nexthdr\n");
395 		return -1;
396 	}
397 	protoff = ipv6_skip_exthdr(skb, extoff, &nexthdr, &frag_off);
398 	/*
399 	 * (protoff == skb->len) means the packet has not data, just
400 	 * IPv6 and possibly extensions headers, but it is tracked anyway
401 	 */
402 	if (protoff < 0 || (frag_off & htons(~0x7)) != 0) {
403 		pr_debug("can't find proto in pkt\n");
404 		return -1;
405 	}
406 
407 	*protonum = nexthdr;
408 	return protoff;
409 }
410 #endif
411 
get_l4proto(const struct sk_buff * skb,unsigned int nhoff,u8 pf,u8 * l4num)412 static int get_l4proto(const struct sk_buff *skb,
413 		       unsigned int nhoff, u8 pf, u8 *l4num)
414 {
415 	switch (pf) {
416 	case NFPROTO_IPV4:
417 		return ipv4_get_l4proto(skb, nhoff, l4num);
418 #if IS_ENABLED(CONFIG_IPV6)
419 	case NFPROTO_IPV6:
420 		return ipv6_get_l4proto(skb, nhoff, l4num);
421 #endif
422 	default:
423 		*l4num = 0;
424 		break;
425 	}
426 	return -1;
427 }
428 
nf_ct_get_tuplepr(const struct sk_buff * skb,unsigned int nhoff,u_int16_t l3num,struct net * net,struct nf_conntrack_tuple * tuple)429 bool nf_ct_get_tuplepr(const struct sk_buff *skb, unsigned int nhoff,
430 		       u_int16_t l3num,
431 		       struct net *net, struct nf_conntrack_tuple *tuple)
432 {
433 	u8 protonum;
434 	int protoff;
435 
436 	protoff = get_l4proto(skb, nhoff, l3num, &protonum);
437 	if (protoff <= 0)
438 		return false;
439 
440 	return nf_ct_get_tuple(skb, nhoff, protoff, l3num, protonum, net, tuple);
441 }
442 EXPORT_SYMBOL_GPL(nf_ct_get_tuplepr);
443 
444 bool
nf_ct_invert_tuple(struct nf_conntrack_tuple * inverse,const struct nf_conntrack_tuple * orig)445 nf_ct_invert_tuple(struct nf_conntrack_tuple *inverse,
446 		   const struct nf_conntrack_tuple *orig)
447 {
448 	memset(inverse, 0, sizeof(*inverse));
449 
450 	inverse->src.l3num = orig->src.l3num;
451 
452 	switch (orig->src.l3num) {
453 	case NFPROTO_IPV4:
454 		inverse->src.u3.ip = orig->dst.u3.ip;
455 		inverse->dst.u3.ip = orig->src.u3.ip;
456 		break;
457 	case NFPROTO_IPV6:
458 		inverse->src.u3.in6 = orig->dst.u3.in6;
459 		inverse->dst.u3.in6 = orig->src.u3.in6;
460 		break;
461 	default:
462 		break;
463 	}
464 
465 	inverse->dst.dir = !orig->dst.dir;
466 
467 	inverse->dst.protonum = orig->dst.protonum;
468 
469 	switch (orig->dst.protonum) {
470 	case IPPROTO_ICMP:
471 		return nf_conntrack_invert_icmp_tuple(inverse, orig);
472 #if IS_ENABLED(CONFIG_IPV6)
473 	case IPPROTO_ICMPV6:
474 		return nf_conntrack_invert_icmpv6_tuple(inverse, orig);
475 #endif
476 	}
477 
478 	inverse->src.u.all = orig->dst.u.all;
479 	inverse->dst.u.all = orig->src.u.all;
480 	return true;
481 }
482 EXPORT_SYMBOL_GPL(nf_ct_invert_tuple);
483 
484 /* Generate a almost-unique pseudo-id for a given conntrack.
485  *
486  * intentionally doesn't re-use any of the seeds used for hash
487  * table location, we assume id gets exposed to userspace.
488  *
489  * Following nf_conn items do not change throughout lifetime
490  * of the nf_conn:
491  *
492  * 1. nf_conn address
493  * 2. nf_conn->master address (normally NULL)
494  * 3. the associated net namespace
495  * 4. the original direction tuple
496  */
nf_ct_get_id(const struct nf_conn * ct)497 u32 nf_ct_get_id(const struct nf_conn *ct)
498 {
499 	static siphash_aligned_key_t ct_id_seed;
500 	unsigned long a, b, c, d;
501 
502 	net_get_random_once(&ct_id_seed, sizeof(ct_id_seed));
503 
504 	a = (unsigned long)ct;
505 	b = (unsigned long)ct->master;
506 	c = (unsigned long)nf_ct_net(ct);
507 	d = (unsigned long)siphash(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
508 				   sizeof(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple),
509 				   &ct_id_seed);
510 #ifdef CONFIG_64BIT
511 	return siphash_4u64((u64)a, (u64)b, (u64)c, (u64)d, &ct_id_seed);
512 #else
513 	return siphash_4u32((u32)a, (u32)b, (u32)c, (u32)d, &ct_id_seed);
514 #endif
515 }
516 EXPORT_SYMBOL_GPL(nf_ct_get_id);
517 
518 static void
clean_from_lists(struct nf_conn * ct)519 clean_from_lists(struct nf_conn *ct)
520 {
521 	pr_debug("clean_from_lists(%p)\n", ct);
522 	hlist_nulls_del_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode);
523 	hlist_nulls_del_rcu(&ct->tuplehash[IP_CT_DIR_REPLY].hnnode);
524 
525 	/* Destroy all pending expectations */
526 	nf_ct_remove_expectations(ct);
527 }
528 
529 #define NFCT_ALIGN(len)	(((len) + NFCT_INFOMASK) & ~NFCT_INFOMASK)
530 
531 /* Released via nf_ct_destroy() */
nf_ct_tmpl_alloc(struct net * net,const struct nf_conntrack_zone * zone,gfp_t flags)532 struct nf_conn *nf_ct_tmpl_alloc(struct net *net,
533 				 const struct nf_conntrack_zone *zone,
534 				 gfp_t flags)
535 {
536 	struct nf_conn *tmpl, *p;
537 
538 	if (ARCH_KMALLOC_MINALIGN <= NFCT_INFOMASK) {
539 		tmpl = kzalloc(sizeof(*tmpl) + NFCT_INFOMASK, flags);
540 		if (!tmpl)
541 			return NULL;
542 
543 		p = tmpl;
544 		tmpl = (struct nf_conn *)NFCT_ALIGN((unsigned long)p);
545 		if (tmpl != p) {
546 			tmpl = (struct nf_conn *)NFCT_ALIGN((unsigned long)p);
547 			tmpl->proto.tmpl_padto = (char *)tmpl - (char *)p;
548 		}
549 	} else {
550 		tmpl = kzalloc(sizeof(*tmpl), flags);
551 		if (!tmpl)
552 			return NULL;
553 	}
554 
555 	tmpl->status = IPS_TEMPLATE;
556 	write_pnet(&tmpl->ct_net, net);
557 	nf_ct_zone_add(tmpl, zone);
558 	refcount_set(&tmpl->ct_general.use, 1);
559 
560 	return tmpl;
561 }
562 EXPORT_SYMBOL_GPL(nf_ct_tmpl_alloc);
563 
nf_ct_tmpl_free(struct nf_conn * tmpl)564 void nf_ct_tmpl_free(struct nf_conn *tmpl)
565 {
566 	kfree(tmpl->ext);
567 
568 	if (ARCH_KMALLOC_MINALIGN <= NFCT_INFOMASK)
569 		kfree((char *)tmpl - tmpl->proto.tmpl_padto);
570 	else
571 		kfree(tmpl);
572 }
573 EXPORT_SYMBOL_GPL(nf_ct_tmpl_free);
574 
destroy_gre_conntrack(struct nf_conn * ct)575 static void destroy_gre_conntrack(struct nf_conn *ct)
576 {
577 #ifdef CONFIG_NF_CT_PROTO_GRE
578 	struct nf_conn *master = ct->master;
579 
580 	if (master)
581 		nf_ct_gre_keymap_destroy(master);
582 #endif
583 }
584 
nf_ct_destroy(struct nf_conntrack * nfct)585 void nf_ct_destroy(struct nf_conntrack *nfct)
586 {
587 	struct nf_conn *ct = (struct nf_conn *)nfct;
588 
589 	pr_debug("%s(%p)\n", __func__, ct);
590 	WARN_ON(refcount_read(&nfct->use) != 0);
591 
592 	if (unlikely(nf_ct_is_template(ct))) {
593 		nf_ct_tmpl_free(ct);
594 		return;
595 	}
596 
597 	if (unlikely(nf_ct_protonum(ct) == IPPROTO_GRE))
598 		destroy_gre_conntrack(ct);
599 
600 	/* Expectations will have been removed in clean_from_lists,
601 	 * except TFTP can create an expectation on the first packet,
602 	 * before connection is in the list, so we need to clean here,
603 	 * too.
604 	 */
605 	nf_ct_remove_expectations(ct);
606 
607 	if (ct->master)
608 		nf_ct_put(ct->master);
609 
610 	pr_debug("%s: returning ct=%p to slab\n", __func__, ct);
611 	nf_conntrack_free(ct);
612 }
613 EXPORT_SYMBOL(nf_ct_destroy);
614 
__nf_ct_delete_from_lists(struct nf_conn * ct)615 static void __nf_ct_delete_from_lists(struct nf_conn *ct)
616 {
617 	struct net *net = nf_ct_net(ct);
618 	unsigned int hash, reply_hash;
619 	unsigned int sequence;
620 
621 	do {
622 		sequence = read_seqcount_begin(&nf_conntrack_generation);
623 		hash = hash_conntrack(net,
624 				      &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
625 				      nf_ct_zone_id(nf_ct_zone(ct), IP_CT_DIR_ORIGINAL));
626 		reply_hash = hash_conntrack(net,
627 					   &ct->tuplehash[IP_CT_DIR_REPLY].tuple,
628 					   nf_ct_zone_id(nf_ct_zone(ct), IP_CT_DIR_REPLY));
629 	} while (nf_conntrack_double_lock(net, hash, reply_hash, sequence));
630 
631 	clean_from_lists(ct);
632 	nf_conntrack_double_unlock(hash, reply_hash);
633 }
634 
nf_ct_delete_from_lists(struct nf_conn * ct)635 static void nf_ct_delete_from_lists(struct nf_conn *ct)
636 {
637 	nf_ct_helper_destroy(ct);
638 	local_bh_disable();
639 
640 	__nf_ct_delete_from_lists(ct);
641 
642 	local_bh_enable();
643 }
644 
nf_ct_add_to_ecache_list(struct nf_conn * ct)645 static void nf_ct_add_to_ecache_list(struct nf_conn *ct)
646 {
647 #ifdef CONFIG_NF_CONNTRACK_EVENTS
648 	struct nf_conntrack_net *cnet = nf_ct_pernet(nf_ct_net(ct));
649 
650 	spin_lock(&cnet->ecache.dying_lock);
651 	hlist_nulls_add_head_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode,
652 				 &cnet->ecache.dying_list);
653 	spin_unlock(&cnet->ecache.dying_lock);
654 #endif
655 }
656 
nf_ct_delete(struct nf_conn * ct,u32 portid,int report)657 bool nf_ct_delete(struct nf_conn *ct, u32 portid, int report)
658 {
659 	struct nf_conn_tstamp *tstamp;
660 	struct net *net;
661 
662 	if (test_and_set_bit(IPS_DYING_BIT, &ct->status))
663 		return false;
664 
665 	tstamp = nf_conn_tstamp_find(ct);
666 	if (tstamp) {
667 		s32 timeout = READ_ONCE(ct->timeout) - nfct_time_stamp;
668 
669 		tstamp->stop = ktime_get_real_ns();
670 		if (timeout < 0)
671 			tstamp->stop -= jiffies_to_nsecs(-timeout);
672 	}
673 
674 	if (nf_conntrack_event_report(IPCT_DESTROY, ct,
675 				    portid, report) < 0) {
676 		/* destroy event was not delivered. nf_ct_put will
677 		 * be done by event cache worker on redelivery.
678 		 */
679 		nf_ct_helper_destroy(ct);
680 		local_bh_disable();
681 		__nf_ct_delete_from_lists(ct);
682 		nf_ct_add_to_ecache_list(ct);
683 		local_bh_enable();
684 
685 		nf_conntrack_ecache_work(nf_ct_net(ct), NFCT_ECACHE_DESTROY_FAIL);
686 		return false;
687 	}
688 
689 	net = nf_ct_net(ct);
690 	if (nf_conntrack_ecache_dwork_pending(net))
691 		nf_conntrack_ecache_work(net, NFCT_ECACHE_DESTROY_SENT);
692 	nf_ct_delete_from_lists(ct);
693 	nf_ct_put(ct);
694 	return true;
695 }
696 EXPORT_SYMBOL_GPL(nf_ct_delete);
697 
698 static inline bool
nf_ct_key_equal(struct nf_conntrack_tuple_hash * h,const struct nf_conntrack_tuple * tuple,const struct nf_conntrack_zone * zone,const struct net * net)699 nf_ct_key_equal(struct nf_conntrack_tuple_hash *h,
700 		const struct nf_conntrack_tuple *tuple,
701 		const struct nf_conntrack_zone *zone,
702 		const struct net *net)
703 {
704 	struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
705 
706 	/* A conntrack can be recreated with the equal tuple,
707 	 * so we need to check that the conntrack is confirmed
708 	 */
709 	return nf_ct_tuple_equal(tuple, &h->tuple) &&
710 	       nf_ct_zone_equal(ct, zone, NF_CT_DIRECTION(h)) &&
711 	       nf_ct_is_confirmed(ct) &&
712 	       net_eq(net, nf_ct_net(ct));
713 }
714 
715 static inline bool
nf_ct_match(const struct nf_conn * ct1,const struct nf_conn * ct2)716 nf_ct_match(const struct nf_conn *ct1, const struct nf_conn *ct2)
717 {
718 	return nf_ct_tuple_equal(&ct1->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
719 				 &ct2->tuplehash[IP_CT_DIR_ORIGINAL].tuple) &&
720 	       nf_ct_tuple_equal(&ct1->tuplehash[IP_CT_DIR_REPLY].tuple,
721 				 &ct2->tuplehash[IP_CT_DIR_REPLY].tuple) &&
722 	       nf_ct_zone_equal(ct1, nf_ct_zone(ct2), IP_CT_DIR_ORIGINAL) &&
723 	       nf_ct_zone_equal(ct1, nf_ct_zone(ct2), IP_CT_DIR_REPLY) &&
724 	       net_eq(nf_ct_net(ct1), nf_ct_net(ct2));
725 }
726 
727 /* caller must hold rcu readlock and none of the nf_conntrack_locks */
nf_ct_gc_expired(struct nf_conn * ct)728 static void nf_ct_gc_expired(struct nf_conn *ct)
729 {
730 	if (!refcount_inc_not_zero(&ct->ct_general.use))
731 		return;
732 
733 	/* load ->status after refcount increase */
734 	smp_acquire__after_ctrl_dep();
735 
736 	if (nf_ct_should_gc(ct))
737 		nf_ct_kill(ct);
738 
739 	nf_ct_put(ct);
740 }
741 
742 /*
743  * Warning :
744  * - Caller must take a reference on returned object
745  *   and recheck nf_ct_tuple_equal(tuple, &h->tuple)
746  */
747 static struct nf_conntrack_tuple_hash *
____nf_conntrack_find(struct net * net,const struct nf_conntrack_zone * zone,const struct nf_conntrack_tuple * tuple,u32 hash)748 ____nf_conntrack_find(struct net *net, const struct nf_conntrack_zone *zone,
749 		      const struct nf_conntrack_tuple *tuple, u32 hash)
750 {
751 	struct nf_conntrack_tuple_hash *h;
752 	struct hlist_nulls_head *ct_hash;
753 	struct hlist_nulls_node *n;
754 	unsigned int bucket, hsize;
755 
756 begin:
757 	nf_conntrack_get_ht(&ct_hash, &hsize);
758 	bucket = reciprocal_scale(hash, hsize);
759 
760 	hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[bucket], hnnode) {
761 		struct nf_conn *ct;
762 
763 		ct = nf_ct_tuplehash_to_ctrack(h);
764 		if (nf_ct_is_expired(ct)) {
765 			nf_ct_gc_expired(ct);
766 			continue;
767 		}
768 
769 		if (nf_ct_key_equal(h, tuple, zone, net))
770 			return h;
771 	}
772 	/*
773 	 * if the nulls value we got at the end of this lookup is
774 	 * not the expected one, we must restart lookup.
775 	 * We probably met an item that was moved to another chain.
776 	 */
777 	if (get_nulls_value(n) != bucket) {
778 		NF_CT_STAT_INC_ATOMIC(net, search_restart);
779 		goto begin;
780 	}
781 
782 	return NULL;
783 }
784 
785 /* Find a connection corresponding to a tuple. */
786 static struct nf_conntrack_tuple_hash *
__nf_conntrack_find_get(struct net * net,const struct nf_conntrack_zone * zone,const struct nf_conntrack_tuple * tuple,u32 hash)787 __nf_conntrack_find_get(struct net *net, const struct nf_conntrack_zone *zone,
788 			const struct nf_conntrack_tuple *tuple, u32 hash)
789 {
790 	struct nf_conntrack_tuple_hash *h;
791 	struct nf_conn *ct;
792 
793 	rcu_read_lock();
794 
795 	h = ____nf_conntrack_find(net, zone, tuple, hash);
796 	if (h) {
797 		/* We have a candidate that matches the tuple we're interested
798 		 * in, try to obtain a reference and re-check tuple
799 		 */
800 		ct = nf_ct_tuplehash_to_ctrack(h);
801 		if (likely(refcount_inc_not_zero(&ct->ct_general.use))) {
802 			/* re-check key after refcount */
803 			smp_acquire__after_ctrl_dep();
804 
805 			if (likely(nf_ct_key_equal(h, tuple, zone, net)))
806 				goto found;
807 
808 			/* TYPESAFE_BY_RCU recycled the candidate */
809 			nf_ct_put(ct);
810 		}
811 
812 		h = NULL;
813 	}
814 found:
815 	rcu_read_unlock();
816 
817 	return h;
818 }
819 
820 struct nf_conntrack_tuple_hash *
nf_conntrack_find_get(struct net * net,const struct nf_conntrack_zone * zone,const struct nf_conntrack_tuple * tuple)821 nf_conntrack_find_get(struct net *net, const struct nf_conntrack_zone *zone,
822 		      const struct nf_conntrack_tuple *tuple)
823 {
824 	unsigned int rid, zone_id = nf_ct_zone_id(zone, IP_CT_DIR_ORIGINAL);
825 	struct nf_conntrack_tuple_hash *thash;
826 
827 	thash = __nf_conntrack_find_get(net, zone, tuple,
828 					hash_conntrack_raw(tuple, zone_id, net));
829 
830 	if (thash)
831 		return thash;
832 
833 	rid = nf_ct_zone_id(zone, IP_CT_DIR_REPLY);
834 	if (rid != zone_id)
835 		return __nf_conntrack_find_get(net, zone, tuple,
836 					       hash_conntrack_raw(tuple, rid, net));
837 	return thash;
838 }
839 EXPORT_SYMBOL_GPL(nf_conntrack_find_get);
840 
__nf_conntrack_hash_insert(struct nf_conn * ct,unsigned int hash,unsigned int reply_hash)841 static void __nf_conntrack_hash_insert(struct nf_conn *ct,
842 				       unsigned int hash,
843 				       unsigned int reply_hash)
844 {
845 	hlist_nulls_add_head_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode,
846 			   &nf_conntrack_hash[hash]);
847 	hlist_nulls_add_head_rcu(&ct->tuplehash[IP_CT_DIR_REPLY].hnnode,
848 			   &nf_conntrack_hash[reply_hash]);
849 }
850 
nf_ct_ext_valid_pre(const struct nf_ct_ext * ext)851 static bool nf_ct_ext_valid_pre(const struct nf_ct_ext *ext)
852 {
853 	/* if ext->gen_id is not equal to nf_conntrack_ext_genid, some extensions
854 	 * may contain stale pointers to e.g. helper that has been removed.
855 	 *
856 	 * The helper can't clear this because the nf_conn object isn't in
857 	 * any hash and synchronize_rcu() isn't enough because associated skb
858 	 * might sit in a queue.
859 	 */
860 	return !ext || ext->gen_id == atomic_read(&nf_conntrack_ext_genid);
861 }
862 
nf_ct_ext_valid_post(struct nf_ct_ext * ext)863 static bool nf_ct_ext_valid_post(struct nf_ct_ext *ext)
864 {
865 	if (!ext)
866 		return true;
867 
868 	if (ext->gen_id != atomic_read(&nf_conntrack_ext_genid))
869 		return false;
870 
871 	/* inserted into conntrack table, nf_ct_iterate_cleanup()
872 	 * will find it.  Disable nf_ct_ext_find() id check.
873 	 */
874 	WRITE_ONCE(ext->gen_id, 0);
875 	return true;
876 }
877 
878 int
nf_conntrack_hash_check_insert(struct nf_conn * ct)879 nf_conntrack_hash_check_insert(struct nf_conn *ct)
880 {
881 	const struct nf_conntrack_zone *zone;
882 	struct net *net = nf_ct_net(ct);
883 	unsigned int hash, reply_hash;
884 	struct nf_conntrack_tuple_hash *h;
885 	struct hlist_nulls_node *n;
886 	unsigned int max_chainlen;
887 	unsigned int chainlen = 0;
888 	unsigned int sequence;
889 	int err = -EEXIST;
890 
891 	zone = nf_ct_zone(ct);
892 
893 	if (!nf_ct_ext_valid_pre(ct->ext)) {
894 		NF_CT_STAT_INC_ATOMIC(net, insert_failed);
895 		return -ETIMEDOUT;
896 	}
897 
898 	local_bh_disable();
899 	do {
900 		sequence = read_seqcount_begin(&nf_conntrack_generation);
901 		hash = hash_conntrack(net,
902 				      &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
903 				      nf_ct_zone_id(nf_ct_zone(ct), IP_CT_DIR_ORIGINAL));
904 		reply_hash = hash_conntrack(net,
905 					   &ct->tuplehash[IP_CT_DIR_REPLY].tuple,
906 					   nf_ct_zone_id(nf_ct_zone(ct), IP_CT_DIR_REPLY));
907 	} while (nf_conntrack_double_lock(net, hash, reply_hash, sequence));
908 
909 	max_chainlen = MIN_CHAINLEN + prandom_u32_max(MAX_CHAINLEN);
910 
911 	/* See if there's one in the list already, including reverse */
912 	hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[hash], hnnode) {
913 		if (nf_ct_key_equal(h, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
914 				    zone, net))
915 			goto out;
916 
917 		if (chainlen++ > max_chainlen)
918 			goto chaintoolong;
919 	}
920 
921 	chainlen = 0;
922 
923 	hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[reply_hash], hnnode) {
924 		if (nf_ct_key_equal(h, &ct->tuplehash[IP_CT_DIR_REPLY].tuple,
925 				    zone, net))
926 			goto out;
927 		if (chainlen++ > max_chainlen)
928 			goto chaintoolong;
929 	}
930 
931 	smp_wmb();
932 	/* The caller holds a reference to this object */
933 	refcount_set(&ct->ct_general.use, 2);
934 	__nf_conntrack_hash_insert(ct, hash, reply_hash);
935 	nf_conntrack_double_unlock(hash, reply_hash);
936 	NF_CT_STAT_INC(net, insert);
937 	local_bh_enable();
938 
939 	if (!nf_ct_ext_valid_post(ct->ext)) {
940 		nf_ct_kill(ct);
941 		NF_CT_STAT_INC_ATOMIC(net, drop);
942 		return -ETIMEDOUT;
943 	}
944 
945 	return 0;
946 chaintoolong:
947 	NF_CT_STAT_INC(net, chaintoolong);
948 	err = -ENOSPC;
949 out:
950 	nf_conntrack_double_unlock(hash, reply_hash);
951 	local_bh_enable();
952 	return err;
953 }
954 EXPORT_SYMBOL_GPL(nf_conntrack_hash_check_insert);
955 
nf_ct_acct_add(struct nf_conn * ct,u32 dir,unsigned int packets,unsigned int bytes)956 void nf_ct_acct_add(struct nf_conn *ct, u32 dir, unsigned int packets,
957 		    unsigned int bytes)
958 {
959 	struct nf_conn_acct *acct;
960 
961 	acct = nf_conn_acct_find(ct);
962 	if (acct) {
963 		struct nf_conn_counter *counter = acct->counter;
964 
965 		atomic64_add(packets, &counter[dir].packets);
966 		atomic64_add(bytes, &counter[dir].bytes);
967 	}
968 }
969 EXPORT_SYMBOL_GPL(nf_ct_acct_add);
970 
nf_ct_acct_merge(struct nf_conn * ct,enum ip_conntrack_info ctinfo,const struct nf_conn * loser_ct)971 static void nf_ct_acct_merge(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
972 			     const struct nf_conn *loser_ct)
973 {
974 	struct nf_conn_acct *acct;
975 
976 	acct = nf_conn_acct_find(loser_ct);
977 	if (acct) {
978 		struct nf_conn_counter *counter = acct->counter;
979 		unsigned int bytes;
980 
981 		/* u32 should be fine since we must have seen one packet. */
982 		bytes = atomic64_read(&counter[CTINFO2DIR(ctinfo)].bytes);
983 		nf_ct_acct_update(ct, CTINFO2DIR(ctinfo), bytes);
984 	}
985 }
986 
__nf_conntrack_insert_prepare(struct nf_conn * ct)987 static void __nf_conntrack_insert_prepare(struct nf_conn *ct)
988 {
989 	struct nf_conn_tstamp *tstamp;
990 
991 	refcount_inc(&ct->ct_general.use);
992 
993 	/* set conntrack timestamp, if enabled. */
994 	tstamp = nf_conn_tstamp_find(ct);
995 	if (tstamp)
996 		tstamp->start = ktime_get_real_ns();
997 }
998 
999 /* caller must hold locks to prevent concurrent changes */
__nf_ct_resolve_clash(struct sk_buff * skb,struct nf_conntrack_tuple_hash * h)1000 static int __nf_ct_resolve_clash(struct sk_buff *skb,
1001 				 struct nf_conntrack_tuple_hash *h)
1002 {
1003 	/* This is the conntrack entry already in hashes that won race. */
1004 	struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
1005 	enum ip_conntrack_info ctinfo;
1006 	struct nf_conn *loser_ct;
1007 
1008 	loser_ct = nf_ct_get(skb, &ctinfo);
1009 
1010 	if (nf_ct_is_dying(ct))
1011 		return NF_DROP;
1012 
1013 	if (((ct->status & IPS_NAT_DONE_MASK) == 0) ||
1014 	    nf_ct_match(ct, loser_ct)) {
1015 		struct net *net = nf_ct_net(ct);
1016 
1017 		nf_conntrack_get(&ct->ct_general);
1018 
1019 		nf_ct_acct_merge(ct, ctinfo, loser_ct);
1020 		nf_ct_put(loser_ct);
1021 		nf_ct_set(skb, ct, ctinfo);
1022 
1023 		NF_CT_STAT_INC(net, clash_resolve);
1024 		return NF_ACCEPT;
1025 	}
1026 
1027 	return NF_DROP;
1028 }
1029 
1030 /**
1031  * nf_ct_resolve_clash_harder - attempt to insert clashing conntrack entry
1032  *
1033  * @skb: skb that causes the collision
1034  * @repl_idx: hash slot for reply direction
1035  *
1036  * Called when origin or reply direction had a clash.
1037  * The skb can be handled without packet drop provided the reply direction
1038  * is unique or there the existing entry has the identical tuple in both
1039  * directions.
1040  *
1041  * Caller must hold conntrack table locks to prevent concurrent updates.
1042  *
1043  * Returns NF_DROP if the clash could not be handled.
1044  */
nf_ct_resolve_clash_harder(struct sk_buff * skb,u32 repl_idx)1045 static int nf_ct_resolve_clash_harder(struct sk_buff *skb, u32 repl_idx)
1046 {
1047 	struct nf_conn *loser_ct = (struct nf_conn *)skb_nfct(skb);
1048 	const struct nf_conntrack_zone *zone;
1049 	struct nf_conntrack_tuple_hash *h;
1050 	struct hlist_nulls_node *n;
1051 	struct net *net;
1052 
1053 	zone = nf_ct_zone(loser_ct);
1054 	net = nf_ct_net(loser_ct);
1055 
1056 	/* Reply direction must never result in a clash, unless both origin
1057 	 * and reply tuples are identical.
1058 	 */
1059 	hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[repl_idx], hnnode) {
1060 		if (nf_ct_key_equal(h,
1061 				    &loser_ct->tuplehash[IP_CT_DIR_REPLY].tuple,
1062 				    zone, net))
1063 			return __nf_ct_resolve_clash(skb, h);
1064 	}
1065 
1066 	/* We want the clashing entry to go away real soon: 1 second timeout. */
1067 	WRITE_ONCE(loser_ct->timeout, nfct_time_stamp + HZ);
1068 
1069 	/* IPS_NAT_CLASH removes the entry automatically on the first
1070 	 * reply.  Also prevents UDP tracker from moving the entry to
1071 	 * ASSURED state, i.e. the entry can always be evicted under
1072 	 * pressure.
1073 	 */
1074 	loser_ct->status |= IPS_FIXED_TIMEOUT | IPS_NAT_CLASH;
1075 
1076 	__nf_conntrack_insert_prepare(loser_ct);
1077 
1078 	/* fake add for ORIGINAL dir: we want lookups to only find the entry
1079 	 * already in the table.  This also hides the clashing entry from
1080 	 * ctnetlink iteration, i.e. conntrack -L won't show them.
1081 	 */
1082 	hlist_nulls_add_fake(&loser_ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode);
1083 
1084 	hlist_nulls_add_head_rcu(&loser_ct->tuplehash[IP_CT_DIR_REPLY].hnnode,
1085 				 &nf_conntrack_hash[repl_idx]);
1086 
1087 	NF_CT_STAT_INC(net, clash_resolve);
1088 	return NF_ACCEPT;
1089 }
1090 
1091 /**
1092  * nf_ct_resolve_clash - attempt to handle clash without packet drop
1093  *
1094  * @skb: skb that causes the clash
1095  * @h: tuplehash of the clashing entry already in table
1096  * @reply_hash: hash slot for reply direction
1097  *
1098  * A conntrack entry can be inserted to the connection tracking table
1099  * if there is no existing entry with an identical tuple.
1100  *
1101  * If there is one, @skb (and the assocated, unconfirmed conntrack) has
1102  * to be dropped.  In case @skb is retransmitted, next conntrack lookup
1103  * will find the already-existing entry.
1104  *
1105  * The major problem with such packet drop is the extra delay added by
1106  * the packet loss -- it will take some time for a retransmit to occur
1107  * (or the sender to time out when waiting for a reply).
1108  *
1109  * This function attempts to handle the situation without packet drop.
1110  *
1111  * If @skb has no NAT transformation or if the colliding entries are
1112  * exactly the same, only the to-be-confirmed conntrack entry is discarded
1113  * and @skb is associated with the conntrack entry already in the table.
1114  *
1115  * Failing that, the new, unconfirmed conntrack is still added to the table
1116  * provided that the collision only occurs in the ORIGINAL direction.
1117  * The new entry will be added only in the non-clashing REPLY direction,
1118  * so packets in the ORIGINAL direction will continue to match the existing
1119  * entry.  The new entry will also have a fixed timeout so it expires --
1120  * due to the collision, it will only see reply traffic.
1121  *
1122  * Returns NF_DROP if the clash could not be resolved.
1123  */
1124 static __cold noinline int
nf_ct_resolve_clash(struct sk_buff * skb,struct nf_conntrack_tuple_hash * h,u32 reply_hash)1125 nf_ct_resolve_clash(struct sk_buff *skb, struct nf_conntrack_tuple_hash *h,
1126 		    u32 reply_hash)
1127 {
1128 	/* This is the conntrack entry already in hashes that won race. */
1129 	struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
1130 	const struct nf_conntrack_l4proto *l4proto;
1131 	enum ip_conntrack_info ctinfo;
1132 	struct nf_conn *loser_ct;
1133 	struct net *net;
1134 	int ret;
1135 
1136 	loser_ct = nf_ct_get(skb, &ctinfo);
1137 	net = nf_ct_net(loser_ct);
1138 
1139 	l4proto = nf_ct_l4proto_find(nf_ct_protonum(ct));
1140 	if (!l4proto->allow_clash)
1141 		goto drop;
1142 
1143 	ret = __nf_ct_resolve_clash(skb, h);
1144 	if (ret == NF_ACCEPT)
1145 		return ret;
1146 
1147 	ret = nf_ct_resolve_clash_harder(skb, reply_hash);
1148 	if (ret == NF_ACCEPT)
1149 		return ret;
1150 
1151 drop:
1152 	NF_CT_STAT_INC(net, drop);
1153 	NF_CT_STAT_INC(net, insert_failed);
1154 	return NF_DROP;
1155 }
1156 
1157 /* Confirm a connection given skb; places it in hash table */
1158 int
__nf_conntrack_confirm(struct sk_buff * skb)1159 __nf_conntrack_confirm(struct sk_buff *skb)
1160 {
1161 	unsigned int chainlen = 0, sequence, max_chainlen;
1162 	const struct nf_conntrack_zone *zone;
1163 	unsigned int hash, reply_hash;
1164 	struct nf_conntrack_tuple_hash *h;
1165 	struct nf_conn *ct;
1166 	struct nf_conn_help *help;
1167 	struct hlist_nulls_node *n;
1168 	enum ip_conntrack_info ctinfo;
1169 	struct net *net;
1170 	int ret = NF_DROP;
1171 
1172 	ct = nf_ct_get(skb, &ctinfo);
1173 	net = nf_ct_net(ct);
1174 
1175 	/* ipt_REJECT uses nf_conntrack_attach to attach related
1176 	   ICMP/TCP RST packets in other direction.  Actual packet
1177 	   which created connection will be IP_CT_NEW or for an
1178 	   expected connection, IP_CT_RELATED. */
1179 	if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
1180 		return NF_ACCEPT;
1181 
1182 	zone = nf_ct_zone(ct);
1183 	local_bh_disable();
1184 
1185 	do {
1186 		sequence = read_seqcount_begin(&nf_conntrack_generation);
1187 		/* reuse the hash saved before */
1188 		hash = *(unsigned long *)&ct->tuplehash[IP_CT_DIR_REPLY].hnnode.pprev;
1189 		hash = scale_hash(hash);
1190 		reply_hash = hash_conntrack(net,
1191 					   &ct->tuplehash[IP_CT_DIR_REPLY].tuple,
1192 					   nf_ct_zone_id(nf_ct_zone(ct), IP_CT_DIR_REPLY));
1193 	} while (nf_conntrack_double_lock(net, hash, reply_hash, sequence));
1194 
1195 	/* We're not in hash table, and we refuse to set up related
1196 	 * connections for unconfirmed conns.  But packet copies and
1197 	 * REJECT will give spurious warnings here.
1198 	 */
1199 
1200 	/* Another skb with the same unconfirmed conntrack may
1201 	 * win the race. This may happen for bridge(br_flood)
1202 	 * or broadcast/multicast packets do skb_clone with
1203 	 * unconfirmed conntrack.
1204 	 */
1205 	if (unlikely(nf_ct_is_confirmed(ct))) {
1206 		WARN_ON_ONCE(1);
1207 		nf_conntrack_double_unlock(hash, reply_hash);
1208 		local_bh_enable();
1209 		return NF_DROP;
1210 	}
1211 
1212 	if (!nf_ct_ext_valid_pre(ct->ext)) {
1213 		NF_CT_STAT_INC(net, insert_failed);
1214 		goto dying;
1215 	}
1216 
1217 	pr_debug("Confirming conntrack %p\n", ct);
1218 	/* We have to check the DYING flag after unlink to prevent
1219 	 * a race against nf_ct_get_next_corpse() possibly called from
1220 	 * user context, else we insert an already 'dead' hash, blocking
1221 	 * further use of that particular connection -JM.
1222 	 */
1223 	ct->status |= IPS_CONFIRMED;
1224 
1225 	if (unlikely(nf_ct_is_dying(ct))) {
1226 		NF_CT_STAT_INC(net, insert_failed);
1227 		goto dying;
1228 	}
1229 
1230 	max_chainlen = MIN_CHAINLEN + prandom_u32_max(MAX_CHAINLEN);
1231 	/* See if there's one in the list already, including reverse:
1232 	   NAT could have grabbed it without realizing, since we're
1233 	   not in the hash.  If there is, we lost race. */
1234 	hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[hash], hnnode) {
1235 		if (nf_ct_key_equal(h, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
1236 				    zone, net))
1237 			goto out;
1238 		if (chainlen++ > max_chainlen)
1239 			goto chaintoolong;
1240 	}
1241 
1242 	chainlen = 0;
1243 	hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[reply_hash], hnnode) {
1244 		if (nf_ct_key_equal(h, &ct->tuplehash[IP_CT_DIR_REPLY].tuple,
1245 				    zone, net))
1246 			goto out;
1247 		if (chainlen++ > max_chainlen) {
1248 chaintoolong:
1249 			NF_CT_STAT_INC(net, chaintoolong);
1250 			NF_CT_STAT_INC(net, insert_failed);
1251 			ret = NF_DROP;
1252 			goto dying;
1253 		}
1254 	}
1255 
1256 	/* Timer relative to confirmation time, not original
1257 	   setting time, otherwise we'd get timer wrap in
1258 	   weird delay cases. */
1259 	ct->timeout += nfct_time_stamp;
1260 
1261 	__nf_conntrack_insert_prepare(ct);
1262 
1263 	/* Since the lookup is lockless, hash insertion must be done after
1264 	 * starting the timer and setting the CONFIRMED bit. The RCU barriers
1265 	 * guarantee that no other CPU can find the conntrack before the above
1266 	 * stores are visible.
1267 	 */
1268 	__nf_conntrack_hash_insert(ct, hash, reply_hash);
1269 	nf_conntrack_double_unlock(hash, reply_hash);
1270 	local_bh_enable();
1271 
1272 	/* ext area is still valid (rcu read lock is held,
1273 	 * but will go out of scope soon, we need to remove
1274 	 * this conntrack again.
1275 	 */
1276 	if (!nf_ct_ext_valid_post(ct->ext)) {
1277 		nf_ct_kill(ct);
1278 		NF_CT_STAT_INC_ATOMIC(net, drop);
1279 		return NF_DROP;
1280 	}
1281 
1282 	help = nfct_help(ct);
1283 	if (help && help->helper)
1284 		nf_conntrack_event_cache(IPCT_HELPER, ct);
1285 
1286 	nf_conntrack_event_cache(master_ct(ct) ?
1287 				 IPCT_RELATED : IPCT_NEW, ct);
1288 	return NF_ACCEPT;
1289 
1290 out:
1291 	ret = nf_ct_resolve_clash(skb, h, reply_hash);
1292 dying:
1293 	nf_conntrack_double_unlock(hash, reply_hash);
1294 	local_bh_enable();
1295 	return ret;
1296 }
1297 EXPORT_SYMBOL_GPL(__nf_conntrack_confirm);
1298 
1299 /* Returns true if a connection correspondings to the tuple (required
1300    for NAT). */
1301 int
nf_conntrack_tuple_taken(const struct nf_conntrack_tuple * tuple,const struct nf_conn * ignored_conntrack)1302 nf_conntrack_tuple_taken(const struct nf_conntrack_tuple *tuple,
1303 			 const struct nf_conn *ignored_conntrack)
1304 {
1305 	struct net *net = nf_ct_net(ignored_conntrack);
1306 	const struct nf_conntrack_zone *zone;
1307 	struct nf_conntrack_tuple_hash *h;
1308 	struct hlist_nulls_head *ct_hash;
1309 	unsigned int hash, hsize;
1310 	struct hlist_nulls_node *n;
1311 	struct nf_conn *ct;
1312 
1313 	zone = nf_ct_zone(ignored_conntrack);
1314 
1315 	rcu_read_lock();
1316  begin:
1317 	nf_conntrack_get_ht(&ct_hash, &hsize);
1318 	hash = __hash_conntrack(net, tuple, nf_ct_zone_id(zone, IP_CT_DIR_REPLY), hsize);
1319 
1320 	hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[hash], hnnode) {
1321 		ct = nf_ct_tuplehash_to_ctrack(h);
1322 
1323 		if (ct == ignored_conntrack)
1324 			continue;
1325 
1326 		if (nf_ct_is_expired(ct)) {
1327 			nf_ct_gc_expired(ct);
1328 			continue;
1329 		}
1330 
1331 		if (nf_ct_key_equal(h, tuple, zone, net)) {
1332 			/* Tuple is taken already, so caller will need to find
1333 			 * a new source port to use.
1334 			 *
1335 			 * Only exception:
1336 			 * If the *original tuples* are identical, then both
1337 			 * conntracks refer to the same flow.
1338 			 * This is a rare situation, it can occur e.g. when
1339 			 * more than one UDP packet is sent from same socket
1340 			 * in different threads.
1341 			 *
1342 			 * Let nf_ct_resolve_clash() deal with this later.
1343 			 */
1344 			if (nf_ct_tuple_equal(&ignored_conntrack->tuplehash[IP_CT_DIR_ORIGINAL].tuple,
1345 					      &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple) &&
1346 					      nf_ct_zone_equal(ct, zone, IP_CT_DIR_ORIGINAL))
1347 				continue;
1348 
1349 			NF_CT_STAT_INC_ATOMIC(net, found);
1350 			rcu_read_unlock();
1351 			return 1;
1352 		}
1353 	}
1354 
1355 	if (get_nulls_value(n) != hash) {
1356 		NF_CT_STAT_INC_ATOMIC(net, search_restart);
1357 		goto begin;
1358 	}
1359 
1360 	rcu_read_unlock();
1361 
1362 	return 0;
1363 }
1364 EXPORT_SYMBOL_GPL(nf_conntrack_tuple_taken);
1365 
1366 #define NF_CT_EVICTION_RANGE	8
1367 
1368 /* There's a small race here where we may free a just-assured
1369    connection.  Too bad: we're in trouble anyway. */
early_drop_list(struct net * net,struct hlist_nulls_head * head)1370 static unsigned int early_drop_list(struct net *net,
1371 				    struct hlist_nulls_head *head)
1372 {
1373 	struct nf_conntrack_tuple_hash *h;
1374 	struct hlist_nulls_node *n;
1375 	unsigned int drops = 0;
1376 	struct nf_conn *tmp;
1377 
1378 	hlist_nulls_for_each_entry_rcu(h, n, head, hnnode) {
1379 		tmp = nf_ct_tuplehash_to_ctrack(h);
1380 
1381 		if (test_bit(IPS_OFFLOAD_BIT, &tmp->status))
1382 			continue;
1383 
1384 		if (nf_ct_is_expired(tmp)) {
1385 			nf_ct_gc_expired(tmp);
1386 			continue;
1387 		}
1388 
1389 		if (test_bit(IPS_ASSURED_BIT, &tmp->status) ||
1390 		    !net_eq(nf_ct_net(tmp), net) ||
1391 		    nf_ct_is_dying(tmp))
1392 			continue;
1393 
1394 		if (!refcount_inc_not_zero(&tmp->ct_general.use))
1395 			continue;
1396 
1397 		/* load ->ct_net and ->status after refcount increase */
1398 		smp_acquire__after_ctrl_dep();
1399 
1400 		/* kill only if still in same netns -- might have moved due to
1401 		 * SLAB_TYPESAFE_BY_RCU rules.
1402 		 *
1403 		 * We steal the timer reference.  If that fails timer has
1404 		 * already fired or someone else deleted it. Just drop ref
1405 		 * and move to next entry.
1406 		 */
1407 		if (net_eq(nf_ct_net(tmp), net) &&
1408 		    nf_ct_is_confirmed(tmp) &&
1409 		    nf_ct_delete(tmp, 0, 0))
1410 			drops++;
1411 
1412 		nf_ct_put(tmp);
1413 	}
1414 
1415 	return drops;
1416 }
1417 
early_drop(struct net * net,unsigned int hash)1418 static noinline int early_drop(struct net *net, unsigned int hash)
1419 {
1420 	unsigned int i, bucket;
1421 
1422 	for (i = 0; i < NF_CT_EVICTION_RANGE; i++) {
1423 		struct hlist_nulls_head *ct_hash;
1424 		unsigned int hsize, drops;
1425 
1426 		rcu_read_lock();
1427 		nf_conntrack_get_ht(&ct_hash, &hsize);
1428 		if (!i)
1429 			bucket = reciprocal_scale(hash, hsize);
1430 		else
1431 			bucket = (bucket + 1) % hsize;
1432 
1433 		drops = early_drop_list(net, &ct_hash[bucket]);
1434 		rcu_read_unlock();
1435 
1436 		if (drops) {
1437 			NF_CT_STAT_ADD_ATOMIC(net, early_drop, drops);
1438 			return true;
1439 		}
1440 	}
1441 
1442 	return false;
1443 }
1444 
gc_worker_skip_ct(const struct nf_conn * ct)1445 static bool gc_worker_skip_ct(const struct nf_conn *ct)
1446 {
1447 	return !nf_ct_is_confirmed(ct) || nf_ct_is_dying(ct);
1448 }
1449 
gc_worker_can_early_drop(const struct nf_conn * ct)1450 static bool gc_worker_can_early_drop(const struct nf_conn *ct)
1451 {
1452 	const struct nf_conntrack_l4proto *l4proto;
1453 
1454 	if (!test_bit(IPS_ASSURED_BIT, &ct->status))
1455 		return true;
1456 
1457 	l4proto = nf_ct_l4proto_find(nf_ct_protonum(ct));
1458 	if (l4proto->can_early_drop && l4proto->can_early_drop(ct))
1459 		return true;
1460 
1461 	return false;
1462 }
1463 
gc_worker(struct work_struct * work)1464 static void gc_worker(struct work_struct *work)
1465 {
1466 	unsigned int i, hashsz, nf_conntrack_max95 = 0;
1467 	u32 end_time, start_time = nfct_time_stamp;
1468 	struct conntrack_gc_work *gc_work;
1469 	unsigned int expired_count = 0;
1470 	unsigned long next_run;
1471 	s32 delta_time;
1472 	long count;
1473 
1474 	gc_work = container_of(work, struct conntrack_gc_work, dwork.work);
1475 
1476 	i = gc_work->next_bucket;
1477 	if (gc_work->early_drop)
1478 		nf_conntrack_max95 = nf_conntrack_max / 100u * 95u;
1479 
1480 	if (i == 0) {
1481 		gc_work->avg_timeout = GC_SCAN_INTERVAL_INIT;
1482 		gc_work->count = GC_SCAN_INITIAL_COUNT;
1483 		gc_work->start_time = start_time;
1484 	}
1485 
1486 	next_run = gc_work->avg_timeout;
1487 	count = gc_work->count;
1488 
1489 	end_time = start_time + GC_SCAN_MAX_DURATION;
1490 
1491 	do {
1492 		struct nf_conntrack_tuple_hash *h;
1493 		struct hlist_nulls_head *ct_hash;
1494 		struct hlist_nulls_node *n;
1495 		struct nf_conn *tmp;
1496 
1497 		rcu_read_lock();
1498 
1499 		nf_conntrack_get_ht(&ct_hash, &hashsz);
1500 		if (i >= hashsz) {
1501 			rcu_read_unlock();
1502 			break;
1503 		}
1504 
1505 		hlist_nulls_for_each_entry_rcu(h, n, &ct_hash[i], hnnode) {
1506 			struct nf_conntrack_net *cnet;
1507 			struct net *net;
1508 			long expires;
1509 
1510 			tmp = nf_ct_tuplehash_to_ctrack(h);
1511 
1512 			if (test_bit(IPS_OFFLOAD_BIT, &tmp->status)) {
1513 				nf_ct_offload_timeout(tmp);
1514 				continue;
1515 			}
1516 
1517 			if (expired_count > GC_SCAN_EXPIRED_MAX) {
1518 				rcu_read_unlock();
1519 
1520 				gc_work->next_bucket = i;
1521 				gc_work->avg_timeout = next_run;
1522 				gc_work->count = count;
1523 
1524 				delta_time = nfct_time_stamp - gc_work->start_time;
1525 
1526 				/* re-sched immediately if total cycle time is exceeded */
1527 				next_run = delta_time < (s32)GC_SCAN_INTERVAL_MAX;
1528 				goto early_exit;
1529 			}
1530 
1531 			if (nf_ct_is_expired(tmp)) {
1532 				nf_ct_gc_expired(tmp);
1533 				expired_count++;
1534 				continue;
1535 			}
1536 
1537 			expires = clamp(nf_ct_expires(tmp), GC_SCAN_INTERVAL_MIN, GC_SCAN_INTERVAL_CLAMP);
1538 			expires = (expires - (long)next_run) / ++count;
1539 			next_run += expires;
1540 
1541 			if (nf_conntrack_max95 == 0 || gc_worker_skip_ct(tmp))
1542 				continue;
1543 
1544 			net = nf_ct_net(tmp);
1545 			cnet = nf_ct_pernet(net);
1546 			if (atomic_read(&cnet->count) < nf_conntrack_max95)
1547 				continue;
1548 
1549 			/* need to take reference to avoid possible races */
1550 			if (!refcount_inc_not_zero(&tmp->ct_general.use))
1551 				continue;
1552 
1553 			/* load ->status after refcount increase */
1554 			smp_acquire__after_ctrl_dep();
1555 
1556 			if (gc_worker_skip_ct(tmp)) {
1557 				nf_ct_put(tmp);
1558 				continue;
1559 			}
1560 
1561 			if (gc_worker_can_early_drop(tmp)) {
1562 				nf_ct_kill(tmp);
1563 				expired_count++;
1564 			}
1565 
1566 			nf_ct_put(tmp);
1567 		}
1568 
1569 		/* could check get_nulls_value() here and restart if ct
1570 		 * was moved to another chain.  But given gc is best-effort
1571 		 * we will just continue with next hash slot.
1572 		 */
1573 		rcu_read_unlock();
1574 		cond_resched();
1575 		i++;
1576 
1577 		delta_time = nfct_time_stamp - end_time;
1578 		if (delta_time > 0 && i < hashsz) {
1579 			gc_work->avg_timeout = next_run;
1580 			gc_work->count = count;
1581 			gc_work->next_bucket = i;
1582 			next_run = 0;
1583 			goto early_exit;
1584 		}
1585 	} while (i < hashsz);
1586 
1587 	gc_work->next_bucket = 0;
1588 
1589 	next_run = clamp(next_run, GC_SCAN_INTERVAL_MIN, GC_SCAN_INTERVAL_MAX);
1590 
1591 	delta_time = max_t(s32, nfct_time_stamp - gc_work->start_time, 1);
1592 	if (next_run > (unsigned long)delta_time)
1593 		next_run -= delta_time;
1594 	else
1595 		next_run = 1;
1596 
1597 early_exit:
1598 	if (gc_work->exiting)
1599 		return;
1600 
1601 	if (next_run)
1602 		gc_work->early_drop = false;
1603 
1604 	queue_delayed_work(system_power_efficient_wq, &gc_work->dwork, next_run);
1605 }
1606 
conntrack_gc_work_init(struct conntrack_gc_work * gc_work)1607 static void conntrack_gc_work_init(struct conntrack_gc_work *gc_work)
1608 {
1609 	INIT_DELAYED_WORK(&gc_work->dwork, gc_worker);
1610 	gc_work->exiting = false;
1611 }
1612 
1613 static struct nf_conn *
__nf_conntrack_alloc(struct net * net,const struct nf_conntrack_zone * zone,const struct nf_conntrack_tuple * orig,const struct nf_conntrack_tuple * repl,gfp_t gfp,u32 hash)1614 __nf_conntrack_alloc(struct net *net,
1615 		     const struct nf_conntrack_zone *zone,
1616 		     const struct nf_conntrack_tuple *orig,
1617 		     const struct nf_conntrack_tuple *repl,
1618 		     gfp_t gfp, u32 hash)
1619 {
1620 	struct nf_conntrack_net *cnet = nf_ct_pernet(net);
1621 	unsigned int ct_count;
1622 	struct nf_conn *ct;
1623 
1624 	/* We don't want any race condition at early drop stage */
1625 	ct_count = atomic_inc_return(&cnet->count);
1626 
1627 	if (nf_conntrack_max && unlikely(ct_count > nf_conntrack_max)) {
1628 		if (!early_drop(net, hash)) {
1629 			if (!conntrack_gc_work.early_drop)
1630 				conntrack_gc_work.early_drop = true;
1631 			atomic_dec(&cnet->count);
1632 			net_warn_ratelimited("nf_conntrack: table full, dropping packet\n");
1633 			return ERR_PTR(-ENOMEM);
1634 		}
1635 	}
1636 
1637 	/*
1638 	 * Do not use kmem_cache_zalloc(), as this cache uses
1639 	 * SLAB_TYPESAFE_BY_RCU.
1640 	 */
1641 	ct = kmem_cache_alloc(nf_conntrack_cachep, gfp);
1642 	if (ct == NULL)
1643 		goto out;
1644 
1645 	spin_lock_init(&ct->lock);
1646 	ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple = *orig;
1647 	ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode.pprev = NULL;
1648 	ct->tuplehash[IP_CT_DIR_REPLY].tuple = *repl;
1649 	/* save hash for reusing when confirming */
1650 	*(unsigned long *)(&ct->tuplehash[IP_CT_DIR_REPLY].hnnode.pprev) = hash;
1651 	ct->status = 0;
1652 	WRITE_ONCE(ct->timeout, 0);
1653 	write_pnet(&ct->ct_net, net);
1654 	memset_after(ct, 0, __nfct_init_offset);
1655 
1656 	nf_ct_zone_add(ct, zone);
1657 
1658 	/* Because we use RCU lookups, we set ct_general.use to zero before
1659 	 * this is inserted in any list.
1660 	 */
1661 	refcount_set(&ct->ct_general.use, 0);
1662 	return ct;
1663 out:
1664 	atomic_dec(&cnet->count);
1665 	return ERR_PTR(-ENOMEM);
1666 }
1667 
nf_conntrack_alloc(struct net * net,const struct nf_conntrack_zone * zone,const struct nf_conntrack_tuple * orig,const struct nf_conntrack_tuple * repl,gfp_t gfp)1668 struct nf_conn *nf_conntrack_alloc(struct net *net,
1669 				   const struct nf_conntrack_zone *zone,
1670 				   const struct nf_conntrack_tuple *orig,
1671 				   const struct nf_conntrack_tuple *repl,
1672 				   gfp_t gfp)
1673 {
1674 	return __nf_conntrack_alloc(net, zone, orig, repl, gfp, 0);
1675 }
1676 EXPORT_SYMBOL_GPL(nf_conntrack_alloc);
1677 
nf_conntrack_free(struct nf_conn * ct)1678 void nf_conntrack_free(struct nf_conn *ct)
1679 {
1680 	struct net *net = nf_ct_net(ct);
1681 	struct nf_conntrack_net *cnet;
1682 
1683 	/* A freed object has refcnt == 0, that's
1684 	 * the golden rule for SLAB_TYPESAFE_BY_RCU
1685 	 */
1686 	WARN_ON(refcount_read(&ct->ct_general.use) != 0);
1687 
1688 	if (ct->status & IPS_SRC_NAT_DONE) {
1689 		const struct nf_nat_hook *nat_hook;
1690 
1691 		rcu_read_lock();
1692 		nat_hook = rcu_dereference(nf_nat_hook);
1693 		if (nat_hook)
1694 			nat_hook->remove_nat_bysrc(ct);
1695 		rcu_read_unlock();
1696 	}
1697 
1698 	kfree(ct->ext);
1699 	kmem_cache_free(nf_conntrack_cachep, ct);
1700 	cnet = nf_ct_pernet(net);
1701 
1702 	smp_mb__before_atomic();
1703 	atomic_dec(&cnet->count);
1704 }
1705 EXPORT_SYMBOL_GPL(nf_conntrack_free);
1706 
1707 
1708 /* Allocate a new conntrack: we return -ENOMEM if classification
1709    failed due to stress.  Otherwise it really is unclassifiable. */
1710 static noinline struct nf_conntrack_tuple_hash *
init_conntrack(struct net * net,struct nf_conn * tmpl,const struct nf_conntrack_tuple * tuple,struct sk_buff * skb,unsigned int dataoff,u32 hash)1711 init_conntrack(struct net *net, struct nf_conn *tmpl,
1712 	       const struct nf_conntrack_tuple *tuple,
1713 	       struct sk_buff *skb,
1714 	       unsigned int dataoff, u32 hash)
1715 {
1716 	struct nf_conn *ct;
1717 	struct nf_conn_help *help;
1718 	struct nf_conntrack_tuple repl_tuple;
1719 #ifdef CONFIG_NF_CONNTRACK_EVENTS
1720 	struct nf_conntrack_ecache *ecache;
1721 #endif
1722 	struct nf_conntrack_expect *exp = NULL;
1723 	const struct nf_conntrack_zone *zone;
1724 	struct nf_conn_timeout *timeout_ext;
1725 	struct nf_conntrack_zone tmp;
1726 	struct nf_conntrack_net *cnet;
1727 
1728 	if (!nf_ct_invert_tuple(&repl_tuple, tuple)) {
1729 		pr_debug("Can't invert tuple.\n");
1730 		return NULL;
1731 	}
1732 
1733 	zone = nf_ct_zone_tmpl(tmpl, skb, &tmp);
1734 	ct = __nf_conntrack_alloc(net, zone, tuple, &repl_tuple, GFP_ATOMIC,
1735 				  hash);
1736 	if (IS_ERR(ct))
1737 		return (struct nf_conntrack_tuple_hash *)ct;
1738 
1739 	if (!nf_ct_add_synproxy(ct, tmpl)) {
1740 		nf_conntrack_free(ct);
1741 		return ERR_PTR(-ENOMEM);
1742 	}
1743 
1744 	timeout_ext = tmpl ? nf_ct_timeout_find(tmpl) : NULL;
1745 
1746 	if (timeout_ext)
1747 		nf_ct_timeout_ext_add(ct, rcu_dereference(timeout_ext->timeout),
1748 				      GFP_ATOMIC);
1749 
1750 	nf_ct_acct_ext_add(ct, GFP_ATOMIC);
1751 	nf_ct_tstamp_ext_add(ct, GFP_ATOMIC);
1752 	nf_ct_labels_ext_add(ct);
1753 
1754 #ifdef CONFIG_NF_CONNTRACK_EVENTS
1755 	ecache = tmpl ? nf_ct_ecache_find(tmpl) : NULL;
1756 
1757 	if ((ecache || net->ct.sysctl_events) &&
1758 	    !nf_ct_ecache_ext_add(ct, ecache ? ecache->ctmask : 0,
1759 				  ecache ? ecache->expmask : 0,
1760 				  GFP_ATOMIC)) {
1761 		nf_conntrack_free(ct);
1762 		return ERR_PTR(-ENOMEM);
1763 	}
1764 #endif
1765 
1766 	cnet = nf_ct_pernet(net);
1767 	if (cnet->expect_count) {
1768 		spin_lock_bh(&nf_conntrack_expect_lock);
1769 		exp = nf_ct_find_expectation(net, zone, tuple);
1770 		if (exp) {
1771 			pr_debug("expectation arrives ct=%p exp=%p\n",
1772 				 ct, exp);
1773 			/* Welcome, Mr. Bond.  We've been expecting you... */
1774 			__set_bit(IPS_EXPECTED_BIT, &ct->status);
1775 			/* exp->master safe, refcnt bumped in nf_ct_find_expectation */
1776 			ct->master = exp->master;
1777 			if (exp->helper) {
1778 				help = nf_ct_helper_ext_add(ct, GFP_ATOMIC);
1779 				if (help)
1780 					rcu_assign_pointer(help->helper, exp->helper);
1781 			}
1782 
1783 #ifdef CONFIG_NF_CONNTRACK_MARK
1784 			ct->mark = READ_ONCE(exp->master->mark);
1785 #endif
1786 #ifdef CONFIG_NF_CONNTRACK_SECMARK
1787 			ct->secmark = exp->master->secmark;
1788 #endif
1789 			NF_CT_STAT_INC(net, expect_new);
1790 		}
1791 		spin_unlock_bh(&nf_conntrack_expect_lock);
1792 	}
1793 	if (!exp && tmpl)
1794 		__nf_ct_try_assign_helper(ct, tmpl, GFP_ATOMIC);
1795 
1796 	/* Other CPU might have obtained a pointer to this object before it was
1797 	 * released.  Because refcount is 0, refcount_inc_not_zero() will fail.
1798 	 *
1799 	 * After refcount_set(1) it will succeed; ensure that zeroing of
1800 	 * ct->status and the correct ct->net pointer are visible; else other
1801 	 * core might observe CONFIRMED bit which means the entry is valid and
1802 	 * in the hash table, but its not (anymore).
1803 	 */
1804 	smp_wmb();
1805 
1806 	/* Now it is going to be associated with an sk_buff, set refcount to 1. */
1807 	refcount_set(&ct->ct_general.use, 1);
1808 
1809 	if (exp) {
1810 		if (exp->expectfn)
1811 			exp->expectfn(ct, exp);
1812 		nf_ct_expect_put(exp);
1813 	}
1814 
1815 	return &ct->tuplehash[IP_CT_DIR_ORIGINAL];
1816 }
1817 
1818 /* On success, returns 0, sets skb->_nfct | ctinfo */
1819 static int
resolve_normal_ct(struct nf_conn * tmpl,struct sk_buff * skb,unsigned int dataoff,u_int8_t protonum,const struct nf_hook_state * state)1820 resolve_normal_ct(struct nf_conn *tmpl,
1821 		  struct sk_buff *skb,
1822 		  unsigned int dataoff,
1823 		  u_int8_t protonum,
1824 		  const struct nf_hook_state *state)
1825 {
1826 	const struct nf_conntrack_zone *zone;
1827 	struct nf_conntrack_tuple tuple;
1828 	struct nf_conntrack_tuple_hash *h;
1829 	enum ip_conntrack_info ctinfo;
1830 	struct nf_conntrack_zone tmp;
1831 	u32 hash, zone_id, rid;
1832 	struct nf_conn *ct;
1833 
1834 	if (!nf_ct_get_tuple(skb, skb_network_offset(skb),
1835 			     dataoff, state->pf, protonum, state->net,
1836 			     &tuple)) {
1837 		pr_debug("Can't get tuple\n");
1838 		return 0;
1839 	}
1840 
1841 	/* look for tuple match */
1842 	zone = nf_ct_zone_tmpl(tmpl, skb, &tmp);
1843 
1844 	zone_id = nf_ct_zone_id(zone, IP_CT_DIR_ORIGINAL);
1845 	hash = hash_conntrack_raw(&tuple, zone_id, state->net);
1846 	h = __nf_conntrack_find_get(state->net, zone, &tuple, hash);
1847 
1848 	if (!h) {
1849 		rid = nf_ct_zone_id(zone, IP_CT_DIR_REPLY);
1850 		if (zone_id != rid) {
1851 			u32 tmp = hash_conntrack_raw(&tuple, rid, state->net);
1852 
1853 			h = __nf_conntrack_find_get(state->net, zone, &tuple, tmp);
1854 		}
1855 	}
1856 
1857 	if (!h) {
1858 		h = init_conntrack(state->net, tmpl, &tuple,
1859 				   skb, dataoff, hash);
1860 		if (!h)
1861 			return 0;
1862 		if (IS_ERR(h))
1863 			return PTR_ERR(h);
1864 	}
1865 	ct = nf_ct_tuplehash_to_ctrack(h);
1866 
1867 	/* It exists; we have (non-exclusive) reference. */
1868 	if (NF_CT_DIRECTION(h) == IP_CT_DIR_REPLY) {
1869 		ctinfo = IP_CT_ESTABLISHED_REPLY;
1870 	} else {
1871 		/* Once we've had two way comms, always ESTABLISHED. */
1872 		if (test_bit(IPS_SEEN_REPLY_BIT, &ct->status)) {
1873 			pr_debug("normal packet for %p\n", ct);
1874 			ctinfo = IP_CT_ESTABLISHED;
1875 		} else if (test_bit(IPS_EXPECTED_BIT, &ct->status)) {
1876 			pr_debug("related packet for %p\n", ct);
1877 			ctinfo = IP_CT_RELATED;
1878 		} else {
1879 			pr_debug("new packet for %p\n", ct);
1880 			ctinfo = IP_CT_NEW;
1881 		}
1882 	}
1883 	nf_ct_set(skb, ct, ctinfo);
1884 	return 0;
1885 }
1886 
1887 /*
1888  * icmp packets need special treatment to handle error messages that are
1889  * related to a connection.
1890  *
1891  * Callers need to check if skb has a conntrack assigned when this
1892  * helper returns; in such case skb belongs to an already known connection.
1893  */
1894 static unsigned int __cold
nf_conntrack_handle_icmp(struct nf_conn * tmpl,struct sk_buff * skb,unsigned int dataoff,u8 protonum,const struct nf_hook_state * state)1895 nf_conntrack_handle_icmp(struct nf_conn *tmpl,
1896 			 struct sk_buff *skb,
1897 			 unsigned int dataoff,
1898 			 u8 protonum,
1899 			 const struct nf_hook_state *state)
1900 {
1901 	int ret;
1902 
1903 	if (state->pf == NFPROTO_IPV4 && protonum == IPPROTO_ICMP)
1904 		ret = nf_conntrack_icmpv4_error(tmpl, skb, dataoff, state);
1905 #if IS_ENABLED(CONFIG_IPV6)
1906 	else if (state->pf == NFPROTO_IPV6 && protonum == IPPROTO_ICMPV6)
1907 		ret = nf_conntrack_icmpv6_error(tmpl, skb, dataoff, state);
1908 #endif
1909 	else
1910 		return NF_ACCEPT;
1911 
1912 	if (ret <= 0)
1913 		NF_CT_STAT_INC_ATOMIC(state->net, error);
1914 
1915 	return ret;
1916 }
1917 
generic_packet(struct nf_conn * ct,struct sk_buff * skb,enum ip_conntrack_info ctinfo)1918 static int generic_packet(struct nf_conn *ct, struct sk_buff *skb,
1919 			  enum ip_conntrack_info ctinfo)
1920 {
1921 	const unsigned int *timeout = nf_ct_timeout_lookup(ct);
1922 
1923 	if (!timeout)
1924 		timeout = &nf_generic_pernet(nf_ct_net(ct))->timeout;
1925 
1926 	nf_ct_refresh_acct(ct, ctinfo, skb, *timeout);
1927 	return NF_ACCEPT;
1928 }
1929 
1930 /* Returns verdict for packet, or -1 for invalid. */
nf_conntrack_handle_packet(struct nf_conn * ct,struct sk_buff * skb,unsigned int dataoff,enum ip_conntrack_info ctinfo,const struct nf_hook_state * state)1931 static int nf_conntrack_handle_packet(struct nf_conn *ct,
1932 				      struct sk_buff *skb,
1933 				      unsigned int dataoff,
1934 				      enum ip_conntrack_info ctinfo,
1935 				      const struct nf_hook_state *state)
1936 {
1937 	switch (nf_ct_protonum(ct)) {
1938 	case IPPROTO_TCP:
1939 		return nf_conntrack_tcp_packet(ct, skb, dataoff,
1940 					       ctinfo, state);
1941 	case IPPROTO_UDP:
1942 		return nf_conntrack_udp_packet(ct, skb, dataoff,
1943 					       ctinfo, state);
1944 	case IPPROTO_ICMP:
1945 		return nf_conntrack_icmp_packet(ct, skb, ctinfo, state);
1946 #if IS_ENABLED(CONFIG_IPV6)
1947 	case IPPROTO_ICMPV6:
1948 		return nf_conntrack_icmpv6_packet(ct, skb, ctinfo, state);
1949 #endif
1950 #ifdef CONFIG_NF_CT_PROTO_UDPLITE
1951 	case IPPROTO_UDPLITE:
1952 		return nf_conntrack_udplite_packet(ct, skb, dataoff,
1953 						   ctinfo, state);
1954 #endif
1955 #ifdef CONFIG_NF_CT_PROTO_SCTP
1956 	case IPPROTO_SCTP:
1957 		return nf_conntrack_sctp_packet(ct, skb, dataoff,
1958 						ctinfo, state);
1959 #endif
1960 #ifdef CONFIG_NF_CT_PROTO_DCCP
1961 	case IPPROTO_DCCP:
1962 		return nf_conntrack_dccp_packet(ct, skb, dataoff,
1963 						ctinfo, state);
1964 #endif
1965 #ifdef CONFIG_NF_CT_PROTO_GRE
1966 	case IPPROTO_GRE:
1967 		return nf_conntrack_gre_packet(ct, skb, dataoff,
1968 					       ctinfo, state);
1969 #endif
1970 	}
1971 
1972 	return generic_packet(ct, skb, ctinfo);
1973 }
1974 
1975 unsigned int
nf_conntrack_in(struct sk_buff * skb,const struct nf_hook_state * state)1976 nf_conntrack_in(struct sk_buff *skb, const struct nf_hook_state *state)
1977 {
1978 	enum ip_conntrack_info ctinfo;
1979 	struct nf_conn *ct, *tmpl;
1980 	u_int8_t protonum;
1981 	int dataoff, ret;
1982 
1983 	tmpl = nf_ct_get(skb, &ctinfo);
1984 	if (tmpl || ctinfo == IP_CT_UNTRACKED) {
1985 		/* Previously seen (loopback or untracked)?  Ignore. */
1986 		if ((tmpl && !nf_ct_is_template(tmpl)) ||
1987 		     ctinfo == IP_CT_UNTRACKED)
1988 			return NF_ACCEPT;
1989 		skb->_nfct = 0;
1990 	}
1991 
1992 	/* rcu_read_lock()ed by nf_hook_thresh */
1993 	dataoff = get_l4proto(skb, skb_network_offset(skb), state->pf, &protonum);
1994 	if (dataoff <= 0) {
1995 		pr_debug("not prepared to track yet or error occurred\n");
1996 		NF_CT_STAT_INC_ATOMIC(state->net, invalid);
1997 		ret = NF_ACCEPT;
1998 		goto out;
1999 	}
2000 
2001 	if (protonum == IPPROTO_ICMP || protonum == IPPROTO_ICMPV6) {
2002 		ret = nf_conntrack_handle_icmp(tmpl, skb, dataoff,
2003 					       protonum, state);
2004 		if (ret <= 0) {
2005 			ret = -ret;
2006 			goto out;
2007 		}
2008 		/* ICMP[v6] protocol trackers may assign one conntrack. */
2009 		if (skb->_nfct)
2010 			goto out;
2011 	}
2012 repeat:
2013 	ret = resolve_normal_ct(tmpl, skb, dataoff,
2014 				protonum, state);
2015 	if (ret < 0) {
2016 		/* Too stressed to deal. */
2017 		NF_CT_STAT_INC_ATOMIC(state->net, drop);
2018 		ret = NF_DROP;
2019 		goto out;
2020 	}
2021 
2022 	ct = nf_ct_get(skb, &ctinfo);
2023 	if (!ct) {
2024 		/* Not valid part of a connection */
2025 		NF_CT_STAT_INC_ATOMIC(state->net, invalid);
2026 		ret = NF_ACCEPT;
2027 		goto out;
2028 	}
2029 
2030 	ret = nf_conntrack_handle_packet(ct, skb, dataoff, ctinfo, state);
2031 	if (ret <= 0) {
2032 		/* Invalid: inverse of the return code tells
2033 		 * the netfilter core what to do */
2034 		pr_debug("nf_conntrack_in: Can't track with proto module\n");
2035 		nf_ct_put(ct);
2036 		skb->_nfct = 0;
2037 		/* Special case: TCP tracker reports an attempt to reopen a
2038 		 * closed/aborted connection. We have to go back and create a
2039 		 * fresh conntrack.
2040 		 */
2041 		if (ret == -NF_REPEAT)
2042 			goto repeat;
2043 
2044 		NF_CT_STAT_INC_ATOMIC(state->net, invalid);
2045 		if (ret == -NF_DROP)
2046 			NF_CT_STAT_INC_ATOMIC(state->net, drop);
2047 
2048 		ret = -ret;
2049 		goto out;
2050 	}
2051 
2052 	if (ctinfo == IP_CT_ESTABLISHED_REPLY &&
2053 	    !test_and_set_bit(IPS_SEEN_REPLY_BIT, &ct->status))
2054 		nf_conntrack_event_cache(IPCT_REPLY, ct);
2055 out:
2056 	if (tmpl)
2057 		nf_ct_put(tmpl);
2058 
2059 	return ret;
2060 }
2061 EXPORT_SYMBOL_GPL(nf_conntrack_in);
2062 
2063 /* Alter reply tuple (maybe alter helper).  This is for NAT, and is
2064    implicitly racy: see __nf_conntrack_confirm */
nf_conntrack_alter_reply(struct nf_conn * ct,const struct nf_conntrack_tuple * newreply)2065 void nf_conntrack_alter_reply(struct nf_conn *ct,
2066 			      const struct nf_conntrack_tuple *newreply)
2067 {
2068 	struct nf_conn_help *help = nfct_help(ct);
2069 
2070 	/* Should be unconfirmed, so not in hash table yet */
2071 	WARN_ON(nf_ct_is_confirmed(ct));
2072 
2073 	pr_debug("Altering reply tuple of %p to ", ct);
2074 	nf_ct_dump_tuple(newreply);
2075 
2076 	ct->tuplehash[IP_CT_DIR_REPLY].tuple = *newreply;
2077 	if (ct->master || (help && !hlist_empty(&help->expectations)))
2078 		return;
2079 }
2080 EXPORT_SYMBOL_GPL(nf_conntrack_alter_reply);
2081 
2082 /* Refresh conntrack for this many jiffies and do accounting if do_acct is 1 */
__nf_ct_refresh_acct(struct nf_conn * ct,enum ip_conntrack_info ctinfo,const struct sk_buff * skb,u32 extra_jiffies,bool do_acct)2083 void __nf_ct_refresh_acct(struct nf_conn *ct,
2084 			  enum ip_conntrack_info ctinfo,
2085 			  const struct sk_buff *skb,
2086 			  u32 extra_jiffies,
2087 			  bool do_acct)
2088 {
2089 	/* Only update if this is not a fixed timeout */
2090 	if (test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status))
2091 		goto acct;
2092 
2093 	/* If not in hash table, timer will not be active yet */
2094 	if (nf_ct_is_confirmed(ct))
2095 		extra_jiffies += nfct_time_stamp;
2096 
2097 	if (READ_ONCE(ct->timeout) != extra_jiffies)
2098 		WRITE_ONCE(ct->timeout, extra_jiffies);
2099 acct:
2100 	if (do_acct)
2101 		nf_ct_acct_update(ct, CTINFO2DIR(ctinfo), skb->len);
2102 }
2103 EXPORT_SYMBOL_GPL(__nf_ct_refresh_acct);
2104 
nf_ct_kill_acct(struct nf_conn * ct,enum ip_conntrack_info ctinfo,const struct sk_buff * skb)2105 bool nf_ct_kill_acct(struct nf_conn *ct,
2106 		     enum ip_conntrack_info ctinfo,
2107 		     const struct sk_buff *skb)
2108 {
2109 	nf_ct_acct_update(ct, CTINFO2DIR(ctinfo), skb->len);
2110 
2111 	return nf_ct_delete(ct, 0, 0);
2112 }
2113 EXPORT_SYMBOL_GPL(nf_ct_kill_acct);
2114 
2115 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
2116 
2117 #include <linux/netfilter/nfnetlink.h>
2118 #include <linux/netfilter/nfnetlink_conntrack.h>
2119 #include <linux/mutex.h>
2120 
2121 /* Generic function for tcp/udp/sctp/dccp and alike. */
nf_ct_port_tuple_to_nlattr(struct sk_buff * skb,const struct nf_conntrack_tuple * tuple)2122 int nf_ct_port_tuple_to_nlattr(struct sk_buff *skb,
2123 			       const struct nf_conntrack_tuple *tuple)
2124 {
2125 	if (nla_put_be16(skb, CTA_PROTO_SRC_PORT, tuple->src.u.tcp.port) ||
2126 	    nla_put_be16(skb, CTA_PROTO_DST_PORT, tuple->dst.u.tcp.port))
2127 		goto nla_put_failure;
2128 	return 0;
2129 
2130 nla_put_failure:
2131 	return -1;
2132 }
2133 EXPORT_SYMBOL_GPL(nf_ct_port_tuple_to_nlattr);
2134 
2135 const struct nla_policy nf_ct_port_nla_policy[CTA_PROTO_MAX+1] = {
2136 	[CTA_PROTO_SRC_PORT]  = { .type = NLA_U16 },
2137 	[CTA_PROTO_DST_PORT]  = { .type = NLA_U16 },
2138 };
2139 EXPORT_SYMBOL_GPL(nf_ct_port_nla_policy);
2140 
nf_ct_port_nlattr_to_tuple(struct nlattr * tb[],struct nf_conntrack_tuple * t,u_int32_t flags)2141 int nf_ct_port_nlattr_to_tuple(struct nlattr *tb[],
2142 			       struct nf_conntrack_tuple *t,
2143 			       u_int32_t flags)
2144 {
2145 	if (flags & CTA_FILTER_FLAG(CTA_PROTO_SRC_PORT)) {
2146 		if (!tb[CTA_PROTO_SRC_PORT])
2147 			return -EINVAL;
2148 
2149 		t->src.u.tcp.port = nla_get_be16(tb[CTA_PROTO_SRC_PORT]);
2150 	}
2151 
2152 	if (flags & CTA_FILTER_FLAG(CTA_PROTO_DST_PORT)) {
2153 		if (!tb[CTA_PROTO_DST_PORT])
2154 			return -EINVAL;
2155 
2156 		t->dst.u.tcp.port = nla_get_be16(tb[CTA_PROTO_DST_PORT]);
2157 	}
2158 
2159 	return 0;
2160 }
2161 EXPORT_SYMBOL_GPL(nf_ct_port_nlattr_to_tuple);
2162 
nf_ct_port_nlattr_tuple_size(void)2163 unsigned int nf_ct_port_nlattr_tuple_size(void)
2164 {
2165 	static unsigned int size __read_mostly;
2166 
2167 	if (!size)
2168 		size = nla_policy_len(nf_ct_port_nla_policy, CTA_PROTO_MAX + 1);
2169 
2170 	return size;
2171 }
2172 EXPORT_SYMBOL_GPL(nf_ct_port_nlattr_tuple_size);
2173 #endif
2174 
2175 /* Used by ipt_REJECT and ip6t_REJECT. */
nf_conntrack_attach(struct sk_buff * nskb,const struct sk_buff * skb)2176 static void nf_conntrack_attach(struct sk_buff *nskb, const struct sk_buff *skb)
2177 {
2178 	struct nf_conn *ct;
2179 	enum ip_conntrack_info ctinfo;
2180 
2181 	/* This ICMP is in reverse direction to the packet which caused it */
2182 	ct = nf_ct_get(skb, &ctinfo);
2183 	if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL)
2184 		ctinfo = IP_CT_RELATED_REPLY;
2185 	else
2186 		ctinfo = IP_CT_RELATED;
2187 
2188 	/* Attach to new skbuff, and increment count */
2189 	nf_ct_set(nskb, ct, ctinfo);
2190 	nf_conntrack_get(skb_nfct(nskb));
2191 }
2192 
__nf_conntrack_update(struct net * net,struct sk_buff * skb,struct nf_conn * ct,enum ip_conntrack_info ctinfo)2193 static int __nf_conntrack_update(struct net *net, struct sk_buff *skb,
2194 				 struct nf_conn *ct,
2195 				 enum ip_conntrack_info ctinfo)
2196 {
2197 	const struct nf_nat_hook *nat_hook;
2198 	struct nf_conntrack_tuple_hash *h;
2199 	struct nf_conntrack_tuple tuple;
2200 	unsigned int status;
2201 	int dataoff;
2202 	u16 l3num;
2203 	u8 l4num;
2204 
2205 	l3num = nf_ct_l3num(ct);
2206 
2207 	dataoff = get_l4proto(skb, skb_network_offset(skb), l3num, &l4num);
2208 	if (dataoff <= 0)
2209 		return -1;
2210 
2211 	if (!nf_ct_get_tuple(skb, skb_network_offset(skb), dataoff, l3num,
2212 			     l4num, net, &tuple))
2213 		return -1;
2214 
2215 	if (ct->status & IPS_SRC_NAT) {
2216 		memcpy(tuple.src.u3.all,
2217 		       ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.all,
2218 		       sizeof(tuple.src.u3.all));
2219 		tuple.src.u.all =
2220 			ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.all;
2221 	}
2222 
2223 	if (ct->status & IPS_DST_NAT) {
2224 		memcpy(tuple.dst.u3.all,
2225 		       ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.all,
2226 		       sizeof(tuple.dst.u3.all));
2227 		tuple.dst.u.all =
2228 			ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u.all;
2229 	}
2230 
2231 	h = nf_conntrack_find_get(net, nf_ct_zone(ct), &tuple);
2232 	if (!h)
2233 		return 0;
2234 
2235 	/* Store status bits of the conntrack that is clashing to re-do NAT
2236 	 * mangling according to what it has been done already to this packet.
2237 	 */
2238 	status = ct->status;
2239 
2240 	nf_ct_put(ct);
2241 	ct = nf_ct_tuplehash_to_ctrack(h);
2242 	nf_ct_set(skb, ct, ctinfo);
2243 
2244 	nat_hook = rcu_dereference(nf_nat_hook);
2245 	if (!nat_hook)
2246 		return 0;
2247 
2248 	if (status & IPS_SRC_NAT &&
2249 	    nat_hook->manip_pkt(skb, ct, NF_NAT_MANIP_SRC,
2250 				IP_CT_DIR_ORIGINAL) == NF_DROP)
2251 		return -1;
2252 
2253 	if (status & IPS_DST_NAT &&
2254 	    nat_hook->manip_pkt(skb, ct, NF_NAT_MANIP_DST,
2255 				IP_CT_DIR_ORIGINAL) == NF_DROP)
2256 		return -1;
2257 
2258 	return 0;
2259 }
2260 
2261 /* This packet is coming from userspace via nf_queue, complete the packet
2262  * processing after the helper invocation in nf_confirm().
2263  */
nf_confirm_cthelper(struct sk_buff * skb,struct nf_conn * ct,enum ip_conntrack_info ctinfo)2264 static int nf_confirm_cthelper(struct sk_buff *skb, struct nf_conn *ct,
2265 			       enum ip_conntrack_info ctinfo)
2266 {
2267 	const struct nf_conntrack_helper *helper;
2268 	const struct nf_conn_help *help;
2269 	int protoff;
2270 
2271 	help = nfct_help(ct);
2272 	if (!help)
2273 		return 0;
2274 
2275 	helper = rcu_dereference(help->helper);
2276 	if (!(helper->flags & NF_CT_HELPER_F_USERSPACE))
2277 		return 0;
2278 
2279 	switch (nf_ct_l3num(ct)) {
2280 	case NFPROTO_IPV4:
2281 		protoff = skb_network_offset(skb) + ip_hdrlen(skb);
2282 		break;
2283 #if IS_ENABLED(CONFIG_IPV6)
2284 	case NFPROTO_IPV6: {
2285 		__be16 frag_off;
2286 		u8 pnum;
2287 
2288 		pnum = ipv6_hdr(skb)->nexthdr;
2289 		protoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &pnum,
2290 					   &frag_off);
2291 		if (protoff < 0 || (frag_off & htons(~0x7)) != 0)
2292 			return 0;
2293 		break;
2294 	}
2295 #endif
2296 	default:
2297 		return 0;
2298 	}
2299 
2300 	if (test_bit(IPS_SEQ_ADJUST_BIT, &ct->status) &&
2301 	    !nf_is_loopback_packet(skb)) {
2302 		if (!nf_ct_seq_adjust(skb, ct, ctinfo, protoff)) {
2303 			NF_CT_STAT_INC_ATOMIC(nf_ct_net(ct), drop);
2304 			return -1;
2305 		}
2306 	}
2307 
2308 	/* We've seen it coming out the other side: confirm it */
2309 	return nf_conntrack_confirm(skb) == NF_DROP ? - 1 : 0;
2310 }
2311 
nf_conntrack_update(struct net * net,struct sk_buff * skb)2312 static int nf_conntrack_update(struct net *net, struct sk_buff *skb)
2313 {
2314 	enum ip_conntrack_info ctinfo;
2315 	struct nf_conn *ct;
2316 	int err;
2317 
2318 	ct = nf_ct_get(skb, &ctinfo);
2319 	if (!ct)
2320 		return 0;
2321 
2322 	if (!nf_ct_is_confirmed(ct)) {
2323 		err = __nf_conntrack_update(net, skb, ct, ctinfo);
2324 		if (err < 0)
2325 			return err;
2326 
2327 		ct = nf_ct_get(skb, &ctinfo);
2328 	}
2329 
2330 	return nf_confirm_cthelper(skb, ct, ctinfo);
2331 }
2332 
nf_conntrack_get_tuple_skb(struct nf_conntrack_tuple * dst_tuple,const struct sk_buff * skb)2333 static bool nf_conntrack_get_tuple_skb(struct nf_conntrack_tuple *dst_tuple,
2334 				       const struct sk_buff *skb)
2335 {
2336 	const struct nf_conntrack_tuple *src_tuple;
2337 	const struct nf_conntrack_tuple_hash *hash;
2338 	struct nf_conntrack_tuple srctuple;
2339 	enum ip_conntrack_info ctinfo;
2340 	struct nf_conn *ct;
2341 
2342 	ct = nf_ct_get(skb, &ctinfo);
2343 	if (ct) {
2344 		src_tuple = nf_ct_tuple(ct, CTINFO2DIR(ctinfo));
2345 		memcpy(dst_tuple, src_tuple, sizeof(*dst_tuple));
2346 		return true;
2347 	}
2348 
2349 	if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb),
2350 			       NFPROTO_IPV4, dev_net(skb->dev),
2351 			       &srctuple))
2352 		return false;
2353 
2354 	hash = nf_conntrack_find_get(dev_net(skb->dev),
2355 				     &nf_ct_zone_dflt,
2356 				     &srctuple);
2357 	if (!hash)
2358 		return false;
2359 
2360 	ct = nf_ct_tuplehash_to_ctrack(hash);
2361 	src_tuple = nf_ct_tuple(ct, !hash->tuple.dst.dir);
2362 	memcpy(dst_tuple, src_tuple, sizeof(*dst_tuple));
2363 	nf_ct_put(ct);
2364 
2365 	return true;
2366 }
2367 
2368 /* Bring out ya dead! */
2369 static struct nf_conn *
get_next_corpse(int (* iter)(struct nf_conn * i,void * data),const struct nf_ct_iter_data * iter_data,unsigned int * bucket)2370 get_next_corpse(int (*iter)(struct nf_conn *i, void *data),
2371 		const struct nf_ct_iter_data *iter_data, unsigned int *bucket)
2372 {
2373 	struct nf_conntrack_tuple_hash *h;
2374 	struct nf_conn *ct;
2375 	struct hlist_nulls_node *n;
2376 	spinlock_t *lockp;
2377 
2378 	for (; *bucket < nf_conntrack_htable_size; (*bucket)++) {
2379 		struct hlist_nulls_head *hslot = &nf_conntrack_hash[*bucket];
2380 
2381 		if (hlist_nulls_empty(hslot))
2382 			continue;
2383 
2384 		lockp = &nf_conntrack_locks[*bucket % CONNTRACK_LOCKS];
2385 		local_bh_disable();
2386 		nf_conntrack_lock(lockp);
2387 		hlist_nulls_for_each_entry(h, n, hslot, hnnode) {
2388 			if (NF_CT_DIRECTION(h) != IP_CT_DIR_REPLY)
2389 				continue;
2390 			/* All nf_conn objects are added to hash table twice, one
2391 			 * for original direction tuple, once for the reply tuple.
2392 			 *
2393 			 * Exception: In the IPS_NAT_CLASH case, only the reply
2394 			 * tuple is added (the original tuple already existed for
2395 			 * a different object).
2396 			 *
2397 			 * We only need to call the iterator once for each
2398 			 * conntrack, so we just use the 'reply' direction
2399 			 * tuple while iterating.
2400 			 */
2401 			ct = nf_ct_tuplehash_to_ctrack(h);
2402 
2403 			if (iter_data->net &&
2404 			    !net_eq(iter_data->net, nf_ct_net(ct)))
2405 				continue;
2406 
2407 			if (iter(ct, iter_data->data))
2408 				goto found;
2409 		}
2410 		spin_unlock(lockp);
2411 		local_bh_enable();
2412 		cond_resched();
2413 	}
2414 
2415 	return NULL;
2416 found:
2417 	refcount_inc(&ct->ct_general.use);
2418 	spin_unlock(lockp);
2419 	local_bh_enable();
2420 	return ct;
2421 }
2422 
nf_ct_iterate_cleanup(int (* iter)(struct nf_conn * i,void * data),const struct nf_ct_iter_data * iter_data)2423 static void nf_ct_iterate_cleanup(int (*iter)(struct nf_conn *i, void *data),
2424 				  const struct nf_ct_iter_data *iter_data)
2425 {
2426 	unsigned int bucket = 0;
2427 	struct nf_conn *ct;
2428 
2429 	might_sleep();
2430 
2431 	mutex_lock(&nf_conntrack_mutex);
2432 	while ((ct = get_next_corpse(iter, iter_data, &bucket)) != NULL) {
2433 		/* Time to push up daises... */
2434 
2435 		nf_ct_delete(ct, iter_data->portid, iter_data->report);
2436 		nf_ct_put(ct);
2437 		cond_resched();
2438 	}
2439 	mutex_unlock(&nf_conntrack_mutex);
2440 }
2441 
nf_ct_iterate_cleanup_net(int (* iter)(struct nf_conn * i,void * data),const struct nf_ct_iter_data * iter_data)2442 void nf_ct_iterate_cleanup_net(int (*iter)(struct nf_conn *i, void *data),
2443 			       const struct nf_ct_iter_data *iter_data)
2444 {
2445 	struct net *net = iter_data->net;
2446 	struct nf_conntrack_net *cnet = nf_ct_pernet(net);
2447 
2448 	might_sleep();
2449 
2450 	if (atomic_read(&cnet->count) == 0)
2451 		return;
2452 
2453 	nf_ct_iterate_cleanup(iter, iter_data);
2454 }
2455 EXPORT_SYMBOL_GPL(nf_ct_iterate_cleanup_net);
2456 
2457 /**
2458  * nf_ct_iterate_destroy - destroy unconfirmed conntracks and iterate table
2459  * @iter: callback to invoke for each conntrack
2460  * @data: data to pass to @iter
2461  *
2462  * Like nf_ct_iterate_cleanup, but first marks conntracks on the
2463  * unconfirmed list as dying (so they will not be inserted into
2464  * main table).
2465  *
2466  * Can only be called in module exit path.
2467  */
2468 void
nf_ct_iterate_destroy(int (* iter)(struct nf_conn * i,void * data),void * data)2469 nf_ct_iterate_destroy(int (*iter)(struct nf_conn *i, void *data), void *data)
2470 {
2471 	struct nf_ct_iter_data iter_data = {};
2472 	struct net *net;
2473 
2474 	down_read(&net_rwsem);
2475 	for_each_net(net) {
2476 		struct nf_conntrack_net *cnet = nf_ct_pernet(net);
2477 
2478 		if (atomic_read(&cnet->count) == 0)
2479 			continue;
2480 		nf_queue_nf_hook_drop(net);
2481 	}
2482 	up_read(&net_rwsem);
2483 
2484 	/* Need to wait for netns cleanup worker to finish, if its
2485 	 * running -- it might have deleted a net namespace from
2486 	 * the global list, so hook drop above might not have
2487 	 * affected all namespaces.
2488 	 */
2489 	net_ns_barrier();
2490 
2491 	/* a skb w. unconfirmed conntrack could have been reinjected just
2492 	 * before we called nf_queue_nf_hook_drop().
2493 	 *
2494 	 * This makes sure its inserted into conntrack table.
2495 	 */
2496 	synchronize_net();
2497 
2498 	nf_ct_ext_bump_genid();
2499 	iter_data.data = data;
2500 	nf_ct_iterate_cleanup(iter, &iter_data);
2501 
2502 	/* Another cpu might be in a rcu read section with
2503 	 * rcu protected pointer cleared in iter callback
2504 	 * or hidden via nf_ct_ext_bump_genid() above.
2505 	 *
2506 	 * Wait until those are done.
2507 	 */
2508 	synchronize_rcu();
2509 }
2510 EXPORT_SYMBOL_GPL(nf_ct_iterate_destroy);
2511 
kill_all(struct nf_conn * i,void * data)2512 static int kill_all(struct nf_conn *i, void *data)
2513 {
2514 	return 1;
2515 }
2516 
nf_conntrack_cleanup_start(void)2517 void nf_conntrack_cleanup_start(void)
2518 {
2519 	cleanup_nf_conntrack_bpf();
2520 	conntrack_gc_work.exiting = true;
2521 }
2522 
nf_conntrack_cleanup_end(void)2523 void nf_conntrack_cleanup_end(void)
2524 {
2525 	RCU_INIT_POINTER(nf_ct_hook, NULL);
2526 	cancel_delayed_work_sync(&conntrack_gc_work.dwork);
2527 	kvfree(nf_conntrack_hash);
2528 
2529 	nf_conntrack_proto_fini();
2530 	nf_conntrack_helper_fini();
2531 	nf_conntrack_expect_fini();
2532 
2533 	kmem_cache_destroy(nf_conntrack_cachep);
2534 }
2535 
2536 /*
2537  * Mishearing the voices in his head, our hero wonders how he's
2538  * supposed to kill the mall.
2539  */
nf_conntrack_cleanup_net(struct net * net)2540 void nf_conntrack_cleanup_net(struct net *net)
2541 {
2542 	LIST_HEAD(single);
2543 
2544 	list_add(&net->exit_list, &single);
2545 	nf_conntrack_cleanup_net_list(&single);
2546 }
2547 
nf_conntrack_cleanup_net_list(struct list_head * net_exit_list)2548 void nf_conntrack_cleanup_net_list(struct list_head *net_exit_list)
2549 {
2550 	struct nf_ct_iter_data iter_data = {};
2551 	struct net *net;
2552 	int busy;
2553 
2554 	/*
2555 	 * This makes sure all current packets have passed through
2556 	 *  netfilter framework.  Roll on, two-stage module
2557 	 *  delete...
2558 	 */
2559 	synchronize_net();
2560 i_see_dead_people:
2561 	busy = 0;
2562 	list_for_each_entry(net, net_exit_list, exit_list) {
2563 		struct nf_conntrack_net *cnet = nf_ct_pernet(net);
2564 
2565 		iter_data.net = net;
2566 		nf_ct_iterate_cleanup_net(kill_all, &iter_data);
2567 		if (atomic_read(&cnet->count) != 0)
2568 			busy = 1;
2569 	}
2570 	if (busy) {
2571 		schedule();
2572 		goto i_see_dead_people;
2573 	}
2574 
2575 	list_for_each_entry(net, net_exit_list, exit_list) {
2576 		nf_conntrack_ecache_pernet_fini(net);
2577 		nf_conntrack_expect_pernet_fini(net);
2578 		free_percpu(net->ct.stat);
2579 	}
2580 }
2581 
nf_ct_alloc_hashtable(unsigned int * sizep,int nulls)2582 void *nf_ct_alloc_hashtable(unsigned int *sizep, int nulls)
2583 {
2584 	struct hlist_nulls_head *hash;
2585 	unsigned int nr_slots, i;
2586 
2587 	if (*sizep > (UINT_MAX / sizeof(struct hlist_nulls_head)))
2588 		return NULL;
2589 
2590 	BUILD_BUG_ON(sizeof(struct hlist_nulls_head) != sizeof(struct hlist_head));
2591 	nr_slots = *sizep = roundup(*sizep, PAGE_SIZE / sizeof(struct hlist_nulls_head));
2592 
2593 	hash = kvcalloc(nr_slots, sizeof(struct hlist_nulls_head), GFP_KERNEL);
2594 
2595 	if (hash && nulls)
2596 		for (i = 0; i < nr_slots; i++)
2597 			INIT_HLIST_NULLS_HEAD(&hash[i], i);
2598 
2599 	return hash;
2600 }
2601 EXPORT_SYMBOL_GPL(nf_ct_alloc_hashtable);
2602 
nf_conntrack_hash_resize(unsigned int hashsize)2603 int nf_conntrack_hash_resize(unsigned int hashsize)
2604 {
2605 	int i, bucket;
2606 	unsigned int old_size;
2607 	struct hlist_nulls_head *hash, *old_hash;
2608 	struct nf_conntrack_tuple_hash *h;
2609 	struct nf_conn *ct;
2610 
2611 	if (!hashsize)
2612 		return -EINVAL;
2613 
2614 	hash = nf_ct_alloc_hashtable(&hashsize, 1);
2615 	if (!hash)
2616 		return -ENOMEM;
2617 
2618 	mutex_lock(&nf_conntrack_mutex);
2619 	old_size = nf_conntrack_htable_size;
2620 	if (old_size == hashsize) {
2621 		mutex_unlock(&nf_conntrack_mutex);
2622 		kvfree(hash);
2623 		return 0;
2624 	}
2625 
2626 	local_bh_disable();
2627 	nf_conntrack_all_lock();
2628 	write_seqcount_begin(&nf_conntrack_generation);
2629 
2630 	/* Lookups in the old hash might happen in parallel, which means we
2631 	 * might get false negatives during connection lookup. New connections
2632 	 * created because of a false negative won't make it into the hash
2633 	 * though since that required taking the locks.
2634 	 */
2635 
2636 	for (i = 0; i < nf_conntrack_htable_size; i++) {
2637 		while (!hlist_nulls_empty(&nf_conntrack_hash[i])) {
2638 			unsigned int zone_id;
2639 
2640 			h = hlist_nulls_entry(nf_conntrack_hash[i].first,
2641 					      struct nf_conntrack_tuple_hash, hnnode);
2642 			ct = nf_ct_tuplehash_to_ctrack(h);
2643 			hlist_nulls_del_rcu(&h->hnnode);
2644 
2645 			zone_id = nf_ct_zone_id(nf_ct_zone(ct), NF_CT_DIRECTION(h));
2646 			bucket = __hash_conntrack(nf_ct_net(ct),
2647 						  &h->tuple, zone_id, hashsize);
2648 			hlist_nulls_add_head_rcu(&h->hnnode, &hash[bucket]);
2649 		}
2650 	}
2651 	old_hash = nf_conntrack_hash;
2652 
2653 	nf_conntrack_hash = hash;
2654 	nf_conntrack_htable_size = hashsize;
2655 
2656 	write_seqcount_end(&nf_conntrack_generation);
2657 	nf_conntrack_all_unlock();
2658 	local_bh_enable();
2659 
2660 	mutex_unlock(&nf_conntrack_mutex);
2661 
2662 	synchronize_net();
2663 	kvfree(old_hash);
2664 	return 0;
2665 }
2666 
nf_conntrack_set_hashsize(const char * val,const struct kernel_param * kp)2667 int nf_conntrack_set_hashsize(const char *val, const struct kernel_param *kp)
2668 {
2669 	unsigned int hashsize;
2670 	int rc;
2671 
2672 	if (current->nsproxy->net_ns != &init_net)
2673 		return -EOPNOTSUPP;
2674 
2675 	/* On boot, we can set this without any fancy locking. */
2676 	if (!nf_conntrack_hash)
2677 		return param_set_uint(val, kp);
2678 
2679 	rc = kstrtouint(val, 0, &hashsize);
2680 	if (rc)
2681 		return rc;
2682 
2683 	return nf_conntrack_hash_resize(hashsize);
2684 }
2685 
nf_conntrack_init_start(void)2686 int nf_conntrack_init_start(void)
2687 {
2688 	unsigned long nr_pages = totalram_pages();
2689 	int max_factor = 8;
2690 	int ret = -ENOMEM;
2691 	int i;
2692 
2693 	seqcount_spinlock_init(&nf_conntrack_generation,
2694 			       &nf_conntrack_locks_all_lock);
2695 
2696 	for (i = 0; i < CONNTRACK_LOCKS; i++)
2697 		spin_lock_init(&nf_conntrack_locks[i]);
2698 
2699 	if (!nf_conntrack_htable_size) {
2700 		nf_conntrack_htable_size
2701 			= (((nr_pages << PAGE_SHIFT) / 16384)
2702 			   / sizeof(struct hlist_head));
2703 		if (BITS_PER_LONG >= 64 &&
2704 		    nr_pages > (4 * (1024 * 1024 * 1024 / PAGE_SIZE)))
2705 			nf_conntrack_htable_size = 262144;
2706 		else if (nr_pages > (1024 * 1024 * 1024 / PAGE_SIZE))
2707 			nf_conntrack_htable_size = 65536;
2708 
2709 		if (nf_conntrack_htable_size < 1024)
2710 			nf_conntrack_htable_size = 1024;
2711 		/* Use a max. factor of one by default to keep the average
2712 		 * hash chain length at 2 entries.  Each entry has to be added
2713 		 * twice (once for original direction, once for reply).
2714 		 * When a table size is given we use the old value of 8 to
2715 		 * avoid implicit reduction of the max entries setting.
2716 		 */
2717 		max_factor = 1;
2718 	}
2719 
2720 	nf_conntrack_hash = nf_ct_alloc_hashtable(&nf_conntrack_htable_size, 1);
2721 	if (!nf_conntrack_hash)
2722 		return -ENOMEM;
2723 
2724 	nf_conntrack_max = max_factor * nf_conntrack_htable_size;
2725 
2726 	nf_conntrack_cachep = kmem_cache_create("nf_conntrack",
2727 						sizeof(struct nf_conn),
2728 						NFCT_INFOMASK + 1,
2729 						SLAB_TYPESAFE_BY_RCU | SLAB_HWCACHE_ALIGN, NULL);
2730 	if (!nf_conntrack_cachep)
2731 		goto err_cachep;
2732 
2733 	ret = nf_conntrack_expect_init();
2734 	if (ret < 0)
2735 		goto err_expect;
2736 
2737 	ret = nf_conntrack_helper_init();
2738 	if (ret < 0)
2739 		goto err_helper;
2740 
2741 	ret = nf_conntrack_proto_init();
2742 	if (ret < 0)
2743 		goto err_proto;
2744 
2745 	conntrack_gc_work_init(&conntrack_gc_work);
2746 	queue_delayed_work(system_power_efficient_wq, &conntrack_gc_work.dwork, HZ);
2747 
2748 	ret = register_nf_conntrack_bpf();
2749 	if (ret < 0)
2750 		goto err_kfunc;
2751 
2752 	return 0;
2753 
2754 err_kfunc:
2755 	cancel_delayed_work_sync(&conntrack_gc_work.dwork);
2756 	nf_conntrack_proto_fini();
2757 err_proto:
2758 	nf_conntrack_helper_fini();
2759 err_helper:
2760 	nf_conntrack_expect_fini();
2761 err_expect:
2762 	kmem_cache_destroy(nf_conntrack_cachep);
2763 err_cachep:
2764 	kvfree(nf_conntrack_hash);
2765 	return ret;
2766 }
2767 
2768 static const struct nf_ct_hook nf_conntrack_hook = {
2769 	.update		= nf_conntrack_update,
2770 	.destroy	= nf_ct_destroy,
2771 	.get_tuple_skb  = nf_conntrack_get_tuple_skb,
2772 	.attach		= nf_conntrack_attach,
2773 };
2774 
nf_conntrack_init_end(void)2775 void nf_conntrack_init_end(void)
2776 {
2777 	RCU_INIT_POINTER(nf_ct_hook, &nf_conntrack_hook);
2778 }
2779 
2780 /*
2781  * We need to use special "null" values, not used in hash table
2782  */
2783 #define UNCONFIRMED_NULLS_VAL	((1<<30)+0)
2784 
nf_conntrack_init_net(struct net * net)2785 int nf_conntrack_init_net(struct net *net)
2786 {
2787 	struct nf_conntrack_net *cnet = nf_ct_pernet(net);
2788 	int ret = -ENOMEM;
2789 
2790 	BUILD_BUG_ON(IP_CT_UNTRACKED == IP_CT_NUMBER);
2791 	BUILD_BUG_ON_NOT_POWER_OF_2(CONNTRACK_LOCKS);
2792 	atomic_set(&cnet->count, 0);
2793 
2794 	net->ct.stat = alloc_percpu(struct ip_conntrack_stat);
2795 	if (!net->ct.stat)
2796 		return ret;
2797 
2798 	ret = nf_conntrack_expect_pernet_init(net);
2799 	if (ret < 0)
2800 		goto err_expect;
2801 
2802 	nf_conntrack_acct_pernet_init(net);
2803 	nf_conntrack_tstamp_pernet_init(net);
2804 	nf_conntrack_ecache_pernet_init(net);
2805 	nf_conntrack_proto_pernet_init(net);
2806 
2807 	return 0;
2808 
2809 err_expect:
2810 	free_percpu(net->ct.stat);
2811 	return ret;
2812 }
2813 
2814 /* ctnetlink code shared by both ctnetlink and nf_conntrack_bpf */
2815 
__nf_ct_change_timeout(struct nf_conn * ct,u64 timeout)2816 int __nf_ct_change_timeout(struct nf_conn *ct, u64 timeout)
2817 {
2818 	if (test_bit(IPS_FIXED_TIMEOUT_BIT, &ct->status))
2819 		return -EPERM;
2820 
2821 	__nf_ct_set_timeout(ct, timeout);
2822 
2823 	if (test_bit(IPS_DYING_BIT, &ct->status))
2824 		return -ETIME;
2825 
2826 	return 0;
2827 }
2828 EXPORT_SYMBOL_GPL(__nf_ct_change_timeout);
2829 
__nf_ct_change_status(struct nf_conn * ct,unsigned long on,unsigned long off)2830 void __nf_ct_change_status(struct nf_conn *ct, unsigned long on, unsigned long off)
2831 {
2832 	unsigned int bit;
2833 
2834 	/* Ignore these unchangable bits */
2835 	on &= ~IPS_UNCHANGEABLE_MASK;
2836 	off &= ~IPS_UNCHANGEABLE_MASK;
2837 
2838 	for (bit = 0; bit < __IPS_MAX_BIT; bit++) {
2839 		if (on & (1 << bit))
2840 			set_bit(bit, &ct->status);
2841 		else if (off & (1 << bit))
2842 			clear_bit(bit, &ct->status);
2843 	}
2844 }
2845 EXPORT_SYMBOL_GPL(__nf_ct_change_status);
2846 
nf_ct_change_status_common(struct nf_conn * ct,unsigned int status)2847 int nf_ct_change_status_common(struct nf_conn *ct, unsigned int status)
2848 {
2849 	unsigned long d;
2850 
2851 	d = ct->status ^ status;
2852 
2853 	if (d & (IPS_EXPECTED|IPS_CONFIRMED|IPS_DYING))
2854 		/* unchangeable */
2855 		return -EBUSY;
2856 
2857 	if (d & IPS_SEEN_REPLY && !(status & IPS_SEEN_REPLY))
2858 		/* SEEN_REPLY bit can only be set */
2859 		return -EBUSY;
2860 
2861 	if (d & IPS_ASSURED && !(status & IPS_ASSURED))
2862 		/* ASSURED bit can only be set */
2863 		return -EBUSY;
2864 
2865 	__nf_ct_change_status(ct, status, 0);
2866 	return 0;
2867 }
2868 EXPORT_SYMBOL_GPL(nf_ct_change_status_common);
2869