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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);
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);