2 * inet fragments management
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.
9 * Authors: Pavel Emelyanov <xemul@openvz.org>
10 * Started as consolidation of ipv4/ip_fragment.c,
11 * ipv6/reassembly. and ipv6 nf conntrack reassembly
14 #include <linux/list.h>
15 #include <linux/spinlock.h>
16 #include <linux/module.h>
17 #include <linux/timer.h>
19 #include <linux/random.h>
20 #include <linux/skbuff.h>
21 #include <linux/rtnetlink.h>
22 #include <linux/slab.h>
25 #include <net/inet_frag.h>
26 #include <net/inet_ecn.h>
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
32 const 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
,
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,
47 EXPORT_SYMBOL(ip_frag_ecn_table
);
50 inet_frag_hashfn(const struct inet_frags
*f
, const struct inet_frag_queue
*q
)
52 return f
->hashfn(q
) & (INETFRAGS_HASHSZ
- 1);
55 static void inet_frag_secret_rebuild(unsigned long dummy
)
57 struct inet_frags
*f
= (struct inet_frags
*)dummy
;
58 unsigned long now
= jiffies
;
61 /* Per bucket lock NOT needed here, due to write lock protection */
64 get_random_bytes(&f
->rnd
, sizeof(u32
));
65 for (i
= 0; i
< INETFRAGS_HASHSZ
; i
++) {
66 struct inet_frag_bucket
*hb
;
67 struct inet_frag_queue
*q
;
71 hlist_for_each_entry_safe(q
, n
, &hb
->chain
, list
) {
72 unsigned int hval
= inet_frag_hashfn(f
, q
);
75 struct inet_frag_bucket
*hb_dest
;
79 /* Relink to new hash chain. */
80 hb_dest
= &f
->hash
[hval
];
81 hlist_add_head(&q
->list
, &hb_dest
->chain
);
85 write_unlock(&f
->lock
);
87 mod_timer(&f
->secret_timer
, now
+ f
->secret_interval
);
90 void inet_frags_init(struct inet_frags
*f
)
94 for (i
= 0; i
< INETFRAGS_HASHSZ
; i
++) {
95 struct inet_frag_bucket
*hb
= &f
->hash
[i
];
97 spin_lock_init(&hb
->chain_lock
);
98 INIT_HLIST_HEAD(&hb
->chain
);
100 rwlock_init(&f
->lock
);
102 setup_timer(&f
->secret_timer
, inet_frag_secret_rebuild
,
104 f
->secret_timer
.expires
= jiffies
+ f
->secret_interval
;
105 add_timer(&f
->secret_timer
);
107 EXPORT_SYMBOL(inet_frags_init
);
109 void inet_frags_init_net(struct netns_frags
*nf
)
112 init_frag_mem_limit(nf
);
113 INIT_LIST_HEAD(&nf
->lru_list
);
114 spin_lock_init(&nf
->lru_lock
);
116 EXPORT_SYMBOL(inet_frags_init_net
);
118 void inet_frags_fini(struct inet_frags
*f
)
120 del_timer(&f
->secret_timer
);
122 EXPORT_SYMBOL(inet_frags_fini
);
124 void inet_frags_exit_net(struct netns_frags
*nf
, struct inet_frags
*f
)
129 inet_frag_evictor(nf
, f
, true);
132 percpu_counter_destroy(&nf
->mem
);
134 EXPORT_SYMBOL(inet_frags_exit_net
);
136 static inline void fq_unlink(struct inet_frag_queue
*fq
, struct inet_frags
*f
)
138 struct inet_frag_bucket
*hb
;
142 hash
= inet_frag_hashfn(f
, fq
);
145 spin_lock(&hb
->chain_lock
);
146 hlist_del(&fq
->list
);
147 spin_unlock(&hb
->chain_lock
);
149 read_unlock(&f
->lock
);
150 inet_frag_lru_del(fq
);
153 void inet_frag_kill(struct inet_frag_queue
*fq
, struct inet_frags
*f
)
155 if (del_timer(&fq
->timer
))
156 atomic_dec(&fq
->refcnt
);
158 if (!(fq
->last_in
& INET_FRAG_COMPLETE
)) {
160 atomic_dec(&fq
->refcnt
);
161 fq
->last_in
|= INET_FRAG_COMPLETE
;
164 EXPORT_SYMBOL(inet_frag_kill
);
166 static inline void frag_kfree_skb(struct netns_frags
*nf
, struct inet_frags
*f
,
174 void inet_frag_destroy(struct inet_frag_queue
*q
, struct inet_frags
*f
,
178 struct netns_frags
*nf
;
179 unsigned int sum
, sum_truesize
= 0;
181 WARN_ON(!(q
->last_in
& INET_FRAG_COMPLETE
));
182 WARN_ON(del_timer(&q
->timer
) != 0);
184 /* Release all fragment data. */
188 struct sk_buff
*xp
= fp
->next
;
190 sum_truesize
+= fp
->truesize
;
191 frag_kfree_skb(nf
, f
, fp
);
194 sum
= sum_truesize
+ f
->qsize
;
197 sub_frag_mem_limit(q
, sum
);
204 EXPORT_SYMBOL(inet_frag_destroy
);
206 int inet_frag_evictor(struct netns_frags
*nf
, struct inet_frags
*f
, bool force
)
208 struct inet_frag_queue
*q
;
209 int work
, evicted
= 0;
212 if (frag_mem_limit(nf
) <= nf
->high_thresh
)
216 work
= frag_mem_limit(nf
) - nf
->low_thresh
;
217 while (work
> 0 || force
) {
218 spin_lock(&nf
->lru_lock
);
220 if (list_empty(&nf
->lru_list
)) {
221 spin_unlock(&nf
->lru_lock
);
225 q
= list_first_entry(&nf
->lru_list
,
226 struct inet_frag_queue
, lru_list
);
227 atomic_inc(&q
->refcnt
);
228 /* Remove q from list to avoid several CPUs grabbing it */
229 list_del_init(&q
->lru_list
);
231 spin_unlock(&nf
->lru_lock
);
234 if (!(q
->last_in
& INET_FRAG_COMPLETE
))
235 inet_frag_kill(q
, f
);
236 spin_unlock(&q
->lock
);
238 if (atomic_dec_and_test(&q
->refcnt
))
239 inet_frag_destroy(q
, f
, &work
);
245 EXPORT_SYMBOL(inet_frag_evictor
);
247 static struct inet_frag_queue
*inet_frag_intern(struct netns_frags
*nf
,
248 struct inet_frag_queue
*qp_in
, struct inet_frags
*f
,
251 struct inet_frag_bucket
*hb
;
252 struct inet_frag_queue
*qp
;
255 read_lock(&f
->lock
); /* Protects against hash rebuild */
257 * While we stayed w/o the lock other CPU could update
258 * the rnd seed, so we need to re-calculate the hash
259 * chain. Fortunatelly the qp_in can be used to get one.
261 hash
= inet_frag_hashfn(f
, qp_in
);
263 spin_lock(&hb
->chain_lock
);
266 /* With SMP race we have to recheck hash table, because
267 * such entry could be created on other cpu, while we
268 * released the hash bucket lock.
270 hlist_for_each_entry(qp
, &hb
->chain
, list
) {
271 if (qp
->net
== nf
&& f
->match(qp
, arg
)) {
272 atomic_inc(&qp
->refcnt
);
273 spin_unlock(&hb
->chain_lock
);
274 read_unlock(&f
->lock
);
275 qp_in
->last_in
|= INET_FRAG_COMPLETE
;
276 inet_frag_put(qp_in
, f
);
282 if (!mod_timer(&qp
->timer
, jiffies
+ nf
->timeout
))
283 atomic_inc(&qp
->refcnt
);
285 atomic_inc(&qp
->refcnt
);
286 hlist_add_head(&qp
->list
, &hb
->chain
);
287 inet_frag_lru_add(nf
, qp
);
288 spin_unlock(&hb
->chain_lock
);
289 read_unlock(&f
->lock
);
294 static struct inet_frag_queue
*inet_frag_alloc(struct netns_frags
*nf
,
295 struct inet_frags
*f
, void *arg
)
297 struct inet_frag_queue
*q
;
299 q
= kzalloc(f
->qsize
, GFP_ATOMIC
);
304 f
->constructor(q
, arg
);
305 add_frag_mem_limit(q
, f
->qsize
);
307 setup_timer(&q
->timer
, f
->frag_expire
, (unsigned long)q
);
308 spin_lock_init(&q
->lock
);
309 atomic_set(&q
->refcnt
, 1);
310 INIT_LIST_HEAD(&q
->lru_list
);
315 static struct inet_frag_queue
*inet_frag_create(struct netns_frags
*nf
,
316 struct inet_frags
*f
, void *arg
)
318 struct inet_frag_queue
*q
;
320 q
= inet_frag_alloc(nf
, f
, arg
);
324 return inet_frag_intern(nf
, q
, f
, arg
);
327 struct inet_frag_queue
*inet_frag_find(struct netns_frags
*nf
,
328 struct inet_frags
*f
, void *key
, unsigned int hash
)
331 struct inet_frag_bucket
*hb
;
332 struct inet_frag_queue
*q
;
335 hash
&= (INETFRAGS_HASHSZ
- 1);
338 spin_lock(&hb
->chain_lock
);
339 hlist_for_each_entry(q
, &hb
->chain
, list
) {
340 if (q
->net
== nf
&& f
->match(q
, key
)) {
341 atomic_inc(&q
->refcnt
);
342 spin_unlock(&hb
->chain_lock
);
343 read_unlock(&f
->lock
);
348 spin_unlock(&hb
->chain_lock
);
349 read_unlock(&f
->lock
);
351 if (depth
<= INETFRAGS_MAXDEPTH
)
352 return inet_frag_create(nf
, f
, key
);
354 return ERR_PTR(-ENOBUFS
);
356 EXPORT_SYMBOL(inet_frag_find
);
358 void inet_frag_maybe_warn_overflow(struct inet_frag_queue
*q
,
361 static const char msg
[] = "inet_frag_find: Fragment hash bucket"
362 " list length grew over limit " __stringify(INETFRAGS_MAXDEPTH
)
363 ". Dropping fragment.\n";
365 if (PTR_ERR(q
) == -ENOBUFS
)
366 LIMIT_NETDEBUG(KERN_WARNING
"%s%s", prefix
, msg
);
368 EXPORT_SYMBOL(inet_frag_maybe_warn_overflow
);