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v3.15
  1/*
  2 * inet fragments management
  3 *
  4 *		This program is free software; you can redistribute it and/or
  5 *		modify it under the terms of the GNU General Public License
  6 *		as published by the Free Software Foundation; either version
  7 *		2 of the License, or (at your option) any later version.
  8 *
  9 * 		Authors:	Pavel Emelyanov <xemul@openvz.org>
 10 *				Started as consolidation of ipv4/ip_fragment.c,
 11 *				ipv6/reassembly. and ipv6 nf conntrack reassembly
 12 */
 13
 14#include <linux/list.h>
 15#include <linux/spinlock.h>
 16#include <linux/module.h>
 17#include <linux/timer.h>
 18#include <linux/mm.h>
 19#include <linux/random.h>
 20#include <linux/skbuff.h>
 21#include <linux/rtnetlink.h>
 22#include <linux/slab.h>
 23
 24#include <net/sock.h>
 25#include <net/inet_frag.h>
 26#include <net/inet_ecn.h>
 27
 28/* Given the OR values of all fragments, apply RFC 3168 5.3 requirements
 29 * Value : 0xff if frame should be dropped.
 30 *         0 or INET_ECN_CE value, to be ORed in to final iph->tos field
 31 */
 32const u8 ip_frag_ecn_table[16] = {
 33	/* at least one fragment had CE, and others ECT_0 or ECT_1 */
 34	[IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0]			= INET_ECN_CE,
 35	[IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1]			= INET_ECN_CE,
 36	[IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1]	= INET_ECN_CE,
 37
 38	/* invalid combinations : drop frame */
 39	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE] = 0xff,
 40	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0] = 0xff,
 41	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_1] = 0xff,
 42	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff,
 43	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0] = 0xff,
 44	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1] = 0xff,
 45	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff,
 46};
 47EXPORT_SYMBOL(ip_frag_ecn_table);
 48
 49static void inet_frag_secret_rebuild(unsigned long dummy)
 50{
 51	struct inet_frags *f = (struct inet_frags *)dummy;
 52	unsigned long now = jiffies;
 53	int i;
 54
 55	/* Per bucket lock NOT needed here, due to write lock protection */
 56	write_lock(&f->lock);
 57
 58	get_random_bytes(&f->rnd, sizeof(u32));
 59	for (i = 0; i < INETFRAGS_HASHSZ; i++) {
 60		struct inet_frag_bucket *hb;
 61		struct inet_frag_queue *q;
 62		struct hlist_node *n;
 63
 64		hb = &f->hash[i];
 65		hlist_for_each_entry_safe(q, n, &hb->chain, list) {
 66			unsigned int hval = f->hashfn(q);
 67
 68			if (hval != i) {
 69				struct inet_frag_bucket *hb_dest;
 70
 71				hlist_del(&q->list);
 72
 73				/* Relink to new hash chain. */
 74				hb_dest = &f->hash[hval];
 75				hlist_add_head(&q->list, &hb_dest->chain);
 76			}
 77		}
 78	}
 79	write_unlock(&f->lock);
 80
 81	mod_timer(&f->secret_timer, now + f->secret_interval);
 82}
 83
 84void inet_frags_init(struct inet_frags *f)
 85{
 86	int i;
 87
 88	for (i = 0; i < INETFRAGS_HASHSZ; i++) {
 89		struct inet_frag_bucket *hb = &f->hash[i];
 90
 91		spin_lock_init(&hb->chain_lock);
 92		INIT_HLIST_HEAD(&hb->chain);
 93	}
 94	rwlock_init(&f->lock);
 95
 96	setup_timer(&f->secret_timer, inet_frag_secret_rebuild,
 97			(unsigned long)f);
 98	f->secret_timer.expires = jiffies + f->secret_interval;
 99	add_timer(&f->secret_timer);
100}
101EXPORT_SYMBOL(inet_frags_init);
102
103void inet_frags_init_net(struct netns_frags *nf)
104{
105	nf->nqueues = 0;
106	init_frag_mem_limit(nf);
107	INIT_LIST_HEAD(&nf->lru_list);
108	spin_lock_init(&nf->lru_lock);
109}
110EXPORT_SYMBOL(inet_frags_init_net);
111
112void inet_frags_fini(struct inet_frags *f)
113{
114	del_timer(&f->secret_timer);
 
 
 
 
115}
116EXPORT_SYMBOL(inet_frags_fini);
117
118void inet_frags_exit_net(struct netns_frags *nf, struct inet_frags *f)
119{
120	nf->low_thresh = 0;
 
 
 
 
 
 
 
121
122	local_bh_disable();
123	inet_frag_evictor(nf, f, true);
124	local_bh_enable();
 
 
 
125
126	percpu_counter_destroy(&nf->mem);
127}
128EXPORT_SYMBOL(inet_frags_exit_net);
129
130static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f)
131{
132	struct inet_frag_bucket *hb;
133	unsigned int hash;
134
135	read_lock(&f->lock);
136	hash = f->hashfn(fq);
137	hb = &f->hash[hash];
138
139	spin_lock(&hb->chain_lock);
140	hlist_del(&fq->list);
141	spin_unlock(&hb->chain_lock);
142
143	read_unlock(&f->lock);
144	inet_frag_lru_del(fq);
145}
 
146
147void inet_frag_kill(struct inet_frag_queue *fq, struct inet_frags *f)
148{
149	if (del_timer(&fq->timer))
150		atomic_dec(&fq->refcnt);
 
 
 
151
152	if (!(fq->last_in & INET_FRAG_COMPLETE)) {
153		fq_unlink(fq, f);
154		atomic_dec(&fq->refcnt);
155		fq->last_in |= INET_FRAG_COMPLETE;
156	}
157}
158EXPORT_SYMBOL(inet_frag_kill);
159
160static inline void frag_kfree_skb(struct netns_frags *nf, struct inet_frags *f,
161		struct sk_buff *skb)
162{
163	if (f->skb_free)
164		f->skb_free(skb);
165	kfree_skb(skb);
 
 
 
 
166}
167
168void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f,
169					int *work)
170{
171	struct sk_buff *fp;
172	struct netns_frags *nf;
173	unsigned int sum, sum_truesize = 0;
 
174
175	WARN_ON(!(q->last_in & INET_FRAG_COMPLETE));
176	WARN_ON(del_timer(&q->timer) != 0);
177
178	/* Release all fragment data. */
179	fp = q->fragments;
180	nf = q->net;
 
181	while (fp) {
182		struct sk_buff *xp = fp->next;
183
184		sum_truesize += fp->truesize;
185		frag_kfree_skb(nf, f, fp);
186		fp = xp;
187	}
188	sum = sum_truesize + f->qsize;
189	if (work)
190		*work -= sum;
191	sub_frag_mem_limit(q, sum);
192
193	if (f->destructor)
194		f->destructor(q);
195	kfree(q);
196
 
197}
198EXPORT_SYMBOL(inet_frag_destroy);
199
200int inet_frag_evictor(struct netns_frags *nf, struct inet_frags *f, bool force)
201{
202	struct inet_frag_queue *q;
203	int work, evicted = 0;
204
205	if (!force) {
206		if (frag_mem_limit(nf) <= nf->high_thresh)
207			return 0;
208	}
209
210	work = frag_mem_limit(nf) - nf->low_thresh;
211	while (work > 0 || force) {
212		spin_lock(&nf->lru_lock);
213
214		if (list_empty(&nf->lru_list)) {
215			spin_unlock(&nf->lru_lock);
216			break;
217		}
218
219		q = list_first_entry(&nf->lru_list,
220				struct inet_frag_queue, lru_list);
221		atomic_inc(&q->refcnt);
222		/* Remove q from list to avoid several CPUs grabbing it */
223		list_del_init(&q->lru_list);
224
225		spin_unlock(&nf->lru_lock);
226
227		spin_lock(&q->lock);
228		if (!(q->last_in & INET_FRAG_COMPLETE))
229			inet_frag_kill(q, f);
230		spin_unlock(&q->lock);
231
232		if (atomic_dec_and_test(&q->refcnt))
233			inet_frag_destroy(q, f, &work);
234		evicted++;
235	}
236
237	return evicted;
238}
239EXPORT_SYMBOL(inet_frag_evictor);
240
241static struct inet_frag_queue *inet_frag_intern(struct netns_frags *nf,
242		struct inet_frag_queue *qp_in, struct inet_frags *f,
243		void *arg)
244{
245	struct inet_frag_bucket *hb;
246	struct inet_frag_queue *qp;
247	unsigned int hash;
248
249	read_lock(&f->lock); /* Protects against hash rebuild */
250	/*
251	 * While we stayed w/o the lock other CPU could update
252	 * the rnd seed, so we need to re-calculate the hash
253	 * chain. Fortunatelly the qp_in can be used to get one.
254	 */
255	hash = f->hashfn(qp_in);
256	hb = &f->hash[hash];
257	spin_lock(&hb->chain_lock);
258
259#ifdef CONFIG_SMP
260	/* With SMP race we have to recheck hash table, because
261	 * such entry could be created on other cpu, while we
262	 * released the hash bucket lock.
263	 */
264	hlist_for_each_entry(qp, &hb->chain, list) {
265		if (qp->net == nf && f->match(qp, arg)) {
266			atomic_inc(&qp->refcnt);
267			spin_unlock(&hb->chain_lock);
268			read_unlock(&f->lock);
269			qp_in->last_in |= INET_FRAG_COMPLETE;
270			inet_frag_put(qp_in, f);
271			return qp;
272		}
273	}
274#endif
275	qp = qp_in;
276	if (!mod_timer(&qp->timer, jiffies + nf->timeout))
277		atomic_inc(&qp->refcnt);
278
279	atomic_inc(&qp->refcnt);
280	hlist_add_head(&qp->list, &hb->chain);
281	inet_frag_lru_add(nf, qp);
282	spin_unlock(&hb->chain_lock);
283	read_unlock(&f->lock);
284
285	return qp;
286}
287
288static struct inet_frag_queue *inet_frag_alloc(struct netns_frags *nf,
289		struct inet_frags *f, void *arg)
 
290{
291	struct inet_frag_queue *q;
292
293	q = kzalloc(f->qsize, GFP_ATOMIC);
294	if (q == NULL)
 
 
 
295		return NULL;
296
297	q->net = nf;
298	f->constructor(q, arg);
299	add_frag_mem_limit(q, f->qsize);
300
301	setup_timer(&q->timer, f->frag_expire, (unsigned long)q);
302	spin_lock_init(&q->lock);
303	atomic_set(&q->refcnt, 1);
304	INIT_LIST_HEAD(&q->lru_list);
305
306	return q;
307}
308
309static struct inet_frag_queue *inet_frag_create(struct netns_frags *nf,
310		struct inet_frags *f, void *arg)
311{
 
312	struct inet_frag_queue *q;
 
313
314	q = inet_frag_alloc(nf, f, arg);
315	if (q == NULL)
316		return NULL;
317
318	return inet_frag_intern(nf, q, f, arg);
 
 
 
 
 
 
 
 
 
 
319}
320
321struct inet_frag_queue *inet_frag_find(struct netns_frags *nf,
322		struct inet_frags *f, void *key, unsigned int hash)
323	__releases(&f->lock)
324{
325	struct inet_frag_bucket *hb;
326	struct inet_frag_queue *q;
327	int depth = 0;
328
329	hb = &f->hash[hash];
330
331	spin_lock(&hb->chain_lock);
332	hlist_for_each_entry(q, &hb->chain, list) {
333		if (q->net == nf && f->match(q, key)) {
334			atomic_inc(&q->refcnt);
335			spin_unlock(&hb->chain_lock);
336			read_unlock(&f->lock);
337			return q;
338		}
339		depth++;
340	}
341	spin_unlock(&hb->chain_lock);
342	read_unlock(&f->lock);
343
344	if (depth <= INETFRAGS_MAXDEPTH)
345		return inet_frag_create(nf, f, key);
346	else
347		return ERR_PTR(-ENOBUFS);
348}
349EXPORT_SYMBOL(inet_frag_find);
350
351void inet_frag_maybe_warn_overflow(struct inet_frag_queue *q,
352				   const char *prefix)
353{
354	static const char msg[] = "inet_frag_find: Fragment hash bucket"
355		" list length grew over limit " __stringify(INETFRAGS_MAXDEPTH)
356		". Dropping fragment.\n";
357
358	if (PTR_ERR(q) == -ENOBUFS)
359		LIMIT_NETDEBUG(KERN_WARNING "%s%s", prefix, msg);
360}
361EXPORT_SYMBOL(inet_frag_maybe_warn_overflow);
v4.17
  1/*
  2 * inet fragments management
  3 *
  4 *		This program is free software; you can redistribute it and/or
  5 *		modify it under the terms of the GNU General Public License
  6 *		as published by the Free Software Foundation; either version
  7 *		2 of the License, or (at your option) any later version.
  8 *
  9 * 		Authors:	Pavel Emelyanov <xemul@openvz.org>
 10 *				Started as consolidation of ipv4/ip_fragment.c,
 11 *				ipv6/reassembly. and ipv6 nf conntrack reassembly
 12 */
 13
 14#include <linux/list.h>
 15#include <linux/spinlock.h>
 16#include <linux/module.h>
 17#include <linux/timer.h>
 18#include <linux/mm.h>
 19#include <linux/random.h>
 20#include <linux/skbuff.h>
 21#include <linux/rtnetlink.h>
 22#include <linux/slab.h>
 23
 24#include <net/sock.h>
 25#include <net/inet_frag.h>
 26#include <net/inet_ecn.h>
 27
 28/* Given the OR values of all fragments, apply RFC 3168 5.3 requirements
 29 * Value : 0xff if frame should be dropped.
 30 *         0 or INET_ECN_CE value, to be ORed in to final iph->tos field
 31 */
 32const u8 ip_frag_ecn_table[16] = {
 33	/* at least one fragment had CE, and others ECT_0 or ECT_1 */
 34	[IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0]			= INET_ECN_CE,
 35	[IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1]			= INET_ECN_CE,
 36	[IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1]	= INET_ECN_CE,
 37
 38	/* invalid combinations : drop frame */
 39	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE] = 0xff,
 40	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0] = 0xff,
 41	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_1] = 0xff,
 42	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff,
 43	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0] = 0xff,
 44	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1] = 0xff,
 45	[IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff,
 46};
 47EXPORT_SYMBOL(ip_frag_ecn_table);
 48
 49int inet_frags_init(struct inet_frags *f)
 50{
 51	f->frags_cachep = kmem_cache_create(f->frags_cache_name, f->qsize, 0, 0,
 52					    NULL);
 53	if (!f->frags_cachep)
 54		return -ENOMEM;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 55
 56	return 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 57}
 58EXPORT_SYMBOL(inet_frags_init);
 59
 
 
 
 
 
 
 
 
 
 60void inet_frags_fini(struct inet_frags *f)
 61{
 62	/* We must wait that all inet_frag_destroy_rcu() have completed. */
 63	rcu_barrier();
 64
 65	kmem_cache_destroy(f->frags_cachep);
 66	f->frags_cachep = NULL;
 67}
 68EXPORT_SYMBOL(inet_frags_fini);
 69
 70static void inet_frags_free_cb(void *ptr, void *arg)
 71{
 72	struct inet_frag_queue *fq = ptr;
 73
 74	/* If we can not cancel the timer, it means this frag_queue
 75	 * is already disappearing, we have nothing to do.
 76	 * Otherwise, we own a refcount until the end of this function.
 77	 */
 78	if (!del_timer(&fq->timer))
 79		return;
 80
 81	spin_lock_bh(&fq->lock);
 82	if (!(fq->flags & INET_FRAG_COMPLETE)) {
 83		fq->flags |= INET_FRAG_COMPLETE;
 84		refcount_dec(&fq->refcnt);
 85	}
 86	spin_unlock_bh(&fq->lock);
 87
 88	inet_frag_put(fq);
 89}
 
 90
 91void inet_frags_exit_net(struct netns_frags *nf)
 92{
 93	nf->low_thresh = 0; /* prevent creation of new frags */
 
 
 
 
 
 
 
 
 
 94
 95	rhashtable_free_and_destroy(&nf->rhashtable, inet_frags_free_cb, NULL);
 
 96}
 97EXPORT_SYMBOL(inet_frags_exit_net);
 98
 99void inet_frag_kill(struct inet_frag_queue *fq)
100{
101	if (del_timer(&fq->timer))
102		refcount_dec(&fq->refcnt);
103
104	if (!(fq->flags & INET_FRAG_COMPLETE)) {
105		struct netns_frags *nf = fq->net;
106
107		fq->flags |= INET_FRAG_COMPLETE;
108		rhashtable_remove_fast(&nf->rhashtable, &fq->node, nf->f->rhash_params);
109		refcount_dec(&fq->refcnt);
 
110	}
111}
112EXPORT_SYMBOL(inet_frag_kill);
113
114static void inet_frag_destroy_rcu(struct rcu_head *head)
 
115{
116	struct inet_frag_queue *q = container_of(head, struct inet_frag_queue,
117						 rcu);
118	struct inet_frags *f = q->net->f;
119
120	if (f->destructor)
121		f->destructor(q);
122	kmem_cache_free(f->frags_cachep, q);
123}
124
125void inet_frag_destroy(struct inet_frag_queue *q)
 
126{
127	struct sk_buff *fp;
128	struct netns_frags *nf;
129	unsigned int sum, sum_truesize = 0;
130	struct inet_frags *f;
131
132	WARN_ON(!(q->flags & INET_FRAG_COMPLETE));
133	WARN_ON(del_timer(&q->timer) != 0);
134
135	/* Release all fragment data. */
136	fp = q->fragments;
137	nf = q->net;
138	f = nf->f;
139	while (fp) {
140		struct sk_buff *xp = fp->next;
141
142		sum_truesize += fp->truesize;
143		kfree_skb(fp);
144		fp = xp;
145	}
146	sum = sum_truesize + f->qsize;
 
 
 
147
148	call_rcu(&q->rcu, inet_frag_destroy_rcu);
 
 
149
150	sub_frag_mem_limit(nf, sum);
151}
152EXPORT_SYMBOL(inet_frag_destroy);
153
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
154static struct inet_frag_queue *inet_frag_alloc(struct netns_frags *nf,
155					       struct inet_frags *f,
156					       void *arg)
157{
158	struct inet_frag_queue *q;
159
160	if (!nf->high_thresh || frag_mem_limit(nf) > nf->high_thresh)
161		return NULL;
162
163	q = kmem_cache_zalloc(f->frags_cachep, GFP_ATOMIC);
164	if (!q)
165		return NULL;
166
167	q->net = nf;
168	f->constructor(q, arg);
169	add_frag_mem_limit(nf, f->qsize);
170
171	timer_setup(&q->timer, f->frag_expire, 0);
172	spin_lock_init(&q->lock);
173	refcount_set(&q->refcnt, 3);
 
174
175	return q;
176}
177
178static struct inet_frag_queue *inet_frag_create(struct netns_frags *nf,
179						void *arg)
180{
181	struct inet_frags *f = nf->f;
182	struct inet_frag_queue *q;
183	int err;
184
185	q = inet_frag_alloc(nf, f, arg);
186	if (!q)
187		return NULL;
188
189	mod_timer(&q->timer, jiffies + nf->timeout);
190
191	err = rhashtable_insert_fast(&nf->rhashtable, &q->node,
192				     f->rhash_params);
193	if (err < 0) {
194		q->flags |= INET_FRAG_COMPLETE;
195		inet_frag_kill(q);
196		inet_frag_destroy(q);
197		return NULL;
198	}
199	return q;
200}
201
202/* TODO : call from rcu_read_lock() and no longer use refcount_inc_not_zero() */
203struct inet_frag_queue *inet_frag_find(struct netns_frags *nf, void *key)
 
204{
205	struct inet_frag_queue *fq;
 
 
206
207	rcu_read_lock();
208
209	fq = rhashtable_lookup(&nf->rhashtable, key, nf->f->rhash_params);
210	if (fq) {
211		if (!refcount_inc_not_zero(&fq->refcnt))
212			fq = NULL;
213		rcu_read_unlock();
214		return fq;
 
 
 
215	}
216	rcu_read_unlock();
 
217
218	return inet_frag_create(nf, key);
 
 
 
219}
220EXPORT_SYMBOL(inet_frag_find);