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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/inet_frag.h> |
25 | |
26 | static void inet_frag_secret_rebuild(unsigned long dummy) |
27 | { |
28 | struct inet_frags *f = (struct inet_frags *)dummy; |
29 | unsigned long now = jiffies; |
30 | int i; |
31 | |
32 | write_lock(&f->lock); |
33 | get_random_bytes(&f->rnd, sizeof(u32)); |
34 | for (i = 0; i < INETFRAGS_HASHSZ; i++) { |
35 | struct inet_frag_queue *q; |
36 | struct hlist_node *p, *n; |
37 | |
38 | hlist_for_each_entry_safe(q, p, n, &f->hash[i], list) { |
39 | unsigned int hval = f->hashfn(q); |
40 | |
41 | if (hval != i) { |
42 | hlist_del(&q->list); |
43 | |
44 | /* Relink to new hash chain. */ |
45 | hlist_add_head(&q->list, &f->hash[hval]); |
46 | } |
47 | } |
48 | } |
49 | write_unlock(&f->lock); |
50 | |
51 | mod_timer(&f->secret_timer, now + f->secret_interval); |
52 | } |
53 | |
54 | void inet_frags_init(struct inet_frags *f) |
55 | { |
56 | int i; |
57 | |
58 | for (i = 0; i < INETFRAGS_HASHSZ; i++) |
59 | INIT_HLIST_HEAD(&f->hash[i]); |
60 | |
61 | rwlock_init(&f->lock); |
62 | |
63 | f->rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^ |
64 | (jiffies ^ (jiffies >> 6))); |
65 | |
66 | setup_timer(&f->secret_timer, inet_frag_secret_rebuild, |
67 | (unsigned long)f); |
68 | f->secret_timer.expires = jiffies + f->secret_interval; |
69 | add_timer(&f->secret_timer); |
70 | } |
71 | EXPORT_SYMBOL(inet_frags_init); |
72 | |
73 | void inet_frags_init_net(struct netns_frags *nf) |
74 | { |
75 | nf->nqueues = 0; |
76 | atomic_set(&nf->mem, 0); |
77 | INIT_LIST_HEAD(&nf->lru_list); |
78 | } |
79 | EXPORT_SYMBOL(inet_frags_init_net); |
80 | |
81 | void inet_frags_fini(struct inet_frags *f) |
82 | { |
83 | del_timer(&f->secret_timer); |
84 | } |
85 | EXPORT_SYMBOL(inet_frags_fini); |
86 | |
87 | void inet_frags_exit_net(struct netns_frags *nf, struct inet_frags *f) |
88 | { |
89 | nf->low_thresh = 0; |
90 | |
91 | local_bh_disable(); |
92 | inet_frag_evictor(nf, f); |
93 | local_bh_enable(); |
94 | } |
95 | EXPORT_SYMBOL(inet_frags_exit_net); |
96 | |
97 | static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f) |
98 | { |
99 | write_lock(&f->lock); |
100 | hlist_del(&fq->list); |
101 | list_del(&fq->lru_list); |
102 | fq->net->nqueues--; |
103 | write_unlock(&f->lock); |
104 | } |
105 | |
106 | void inet_frag_kill(struct inet_frag_queue *fq, struct inet_frags *f) |
107 | { |
108 | if (del_timer(&fq->timer)) |
109 | atomic_dec(&fq->refcnt); |
110 | |
111 | if (!(fq->last_in & INET_FRAG_COMPLETE)) { |
112 | fq_unlink(fq, f); |
113 | atomic_dec(&fq->refcnt); |
114 | fq->last_in |= INET_FRAG_COMPLETE; |
115 | } |
116 | } |
117 | |
118 | EXPORT_SYMBOL(inet_frag_kill); |
119 | |
120 | static inline void frag_kfree_skb(struct netns_frags *nf, struct inet_frags *f, |
121 | struct sk_buff *skb, int *work) |
122 | { |
123 | if (work) |
124 | *work -= skb->truesize; |
125 | |
126 | atomic_sub(skb->truesize, &nf->mem); |
127 | if (f->skb_free) |
128 | f->skb_free(skb); |
129 | kfree_skb(skb); |
130 | } |
131 | |
132 | void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f, |
133 | int *work) |
134 | { |
135 | struct sk_buff *fp; |
136 | struct netns_frags *nf; |
137 | |
138 | WARN_ON(!(q->last_in & INET_FRAG_COMPLETE)); |
139 | WARN_ON(del_timer(&q->timer) != 0); |
140 | |
141 | /* Release all fragment data. */ |
142 | fp = q->fragments; |
143 | nf = q->net; |
144 | while (fp) { |
145 | struct sk_buff *xp = fp->next; |
146 | |
147 | frag_kfree_skb(nf, f, fp, work); |
148 | fp = xp; |
149 | } |
150 | |
151 | if (work) |
152 | *work -= f->qsize; |
153 | atomic_sub(f->qsize, &nf->mem); |
154 | |
155 | if (f->destructor) |
156 | f->destructor(q); |
157 | kfree(q); |
158 | |
159 | } |
160 | EXPORT_SYMBOL(inet_frag_destroy); |
161 | |
162 | int inet_frag_evictor(struct netns_frags *nf, struct inet_frags *f) |
163 | { |
164 | struct inet_frag_queue *q; |
165 | int work, evicted = 0; |
166 | |
167 | work = atomic_read(&nf->mem) - nf->low_thresh; |
168 | while (work > 0) { |
169 | read_lock(&f->lock); |
170 | if (list_empty(&nf->lru_list)) { |
171 | read_unlock(&f->lock); |
172 | break; |
173 | } |
174 | |
175 | q = list_first_entry(&nf->lru_list, |
176 | struct inet_frag_queue, lru_list); |
177 | atomic_inc(&q->refcnt); |
178 | read_unlock(&f->lock); |
179 | |
180 | spin_lock(&q->lock); |
181 | if (!(q->last_in & INET_FRAG_COMPLETE)) |
182 | inet_frag_kill(q, f); |
183 | spin_unlock(&q->lock); |
184 | |
185 | if (atomic_dec_and_test(&q->refcnt)) |
186 | inet_frag_destroy(q, f, &work); |
187 | evicted++; |
188 | } |
189 | |
190 | return evicted; |
191 | } |
192 | EXPORT_SYMBOL(inet_frag_evictor); |
193 | |
194 | static struct inet_frag_queue *inet_frag_intern(struct netns_frags *nf, |
195 | struct inet_frag_queue *qp_in, struct inet_frags *f, |
196 | void *arg) |
197 | { |
198 | struct inet_frag_queue *qp; |
199 | #ifdef CONFIG_SMP |
200 | struct hlist_node *n; |
201 | #endif |
202 | unsigned int hash; |
203 | |
204 | write_lock(&f->lock); |
205 | /* |
206 | * While we stayed w/o the lock other CPU could update |
207 | * the rnd seed, so we need to re-calculate the hash |
208 | * chain. Fortunatelly the qp_in can be used to get one. |
209 | */ |
210 | hash = f->hashfn(qp_in); |
211 | #ifdef CONFIG_SMP |
212 | /* With SMP race we have to recheck hash table, because |
213 | * such entry could be created on other cpu, while we |
214 | * promoted read lock to write lock. |
215 | */ |
216 | hlist_for_each_entry(qp, n, &f->hash[hash], list) { |
217 | if (qp->net == nf && f->match(qp, arg)) { |
218 | atomic_inc(&qp->refcnt); |
219 | write_unlock(&f->lock); |
220 | qp_in->last_in |= INET_FRAG_COMPLETE; |
221 | inet_frag_put(qp_in, f); |
222 | return qp; |
223 | } |
224 | } |
225 | #endif |
226 | qp = qp_in; |
227 | if (!mod_timer(&qp->timer, jiffies + nf->timeout)) |
228 | atomic_inc(&qp->refcnt); |
229 | |
230 | atomic_inc(&qp->refcnt); |
231 | hlist_add_head(&qp->list, &f->hash[hash]); |
232 | list_add_tail(&qp->lru_list, &nf->lru_list); |
233 | nf->nqueues++; |
234 | write_unlock(&f->lock); |
235 | return qp; |
236 | } |
237 | |
238 | static struct inet_frag_queue *inet_frag_alloc(struct netns_frags *nf, |
239 | struct inet_frags *f, void *arg) |
240 | { |
241 | struct inet_frag_queue *q; |
242 | |
243 | q = kzalloc(f->qsize, GFP_ATOMIC); |
244 | if (q == NULL) |
245 | return NULL; |
246 | |
247 | f->constructor(q, arg); |
248 | atomic_add(f->qsize, &nf->mem); |
249 | setup_timer(&q->timer, f->frag_expire, (unsigned long)q); |
250 | spin_lock_init(&q->lock); |
251 | atomic_set(&q->refcnt, 1); |
252 | q->net = nf; |
253 | |
254 | return q; |
255 | } |
256 | |
257 | static struct inet_frag_queue *inet_frag_create(struct netns_frags *nf, |
258 | struct inet_frags *f, void *arg) |
259 | { |
260 | struct inet_frag_queue *q; |
261 | |
262 | q = inet_frag_alloc(nf, f, arg); |
263 | if (q == NULL) |
264 | return NULL; |
265 | |
266 | return inet_frag_intern(nf, q, f, arg); |
267 | } |
268 | |
269 | struct inet_frag_queue *inet_frag_find(struct netns_frags *nf, |
270 | struct inet_frags *f, void *key, unsigned int hash) |
271 | __releases(&f->lock) |
272 | { |
273 | struct inet_frag_queue *q; |
274 | struct hlist_node *n; |
275 | |
276 | hlist_for_each_entry(q, n, &f->hash[hash], list) { |
277 | if (q->net == nf && f->match(q, key)) { |
278 | atomic_inc(&q->refcnt); |
279 | read_unlock(&f->lock); |
280 | return q; |
281 | } |
282 | } |
283 | read_unlock(&f->lock); |
284 | |
285 | return inet_frag_create(nf, f, key); |
286 | } |
287 | EXPORT_SYMBOL(inet_frag_find); |
288 |
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