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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 | |
23 | #include <net/inet_frag.h> |
24 | |
25 | static void inet_frag_secret_rebuild(unsigned long dummy) |
26 | { |
27 | struct inet_frags *f = (struct inet_frags *)dummy; |
28 | unsigned long now = jiffies; |
29 | int i; |
30 | |
31 | write_lock(&f->lock); |
32 | get_random_bytes(&f->rnd, sizeof(u32)); |
33 | for (i = 0; i < INETFRAGS_HASHSZ; i++) { |
34 | struct inet_frag_queue *q; |
35 | struct hlist_node *p, *n; |
36 | |
37 | hlist_for_each_entry_safe(q, p, n, &f->hash[i], list) { |
38 | unsigned int hval = f->hashfn(q); |
39 | |
40 | if (hval != i) { |
41 | hlist_del(&q->list); |
42 | |
43 | /* Relink to new hash chain. */ |
44 | hlist_add_head(&q->list, &f->hash[hval]); |
45 | } |
46 | } |
47 | } |
48 | write_unlock(&f->lock); |
49 | |
50 | mod_timer(&f->secret_timer, now + f->secret_interval); |
51 | } |
52 | |
53 | void inet_frags_init(struct inet_frags *f) |
54 | { |
55 | int i; |
56 | |
57 | for (i = 0; i < INETFRAGS_HASHSZ; i++) |
58 | INIT_HLIST_HEAD(&f->hash[i]); |
59 | |
60 | rwlock_init(&f->lock); |
61 | |
62 | f->rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^ |
63 | (jiffies ^ (jiffies >> 6))); |
64 | |
65 | setup_timer(&f->secret_timer, inet_frag_secret_rebuild, |
66 | (unsigned long)f); |
67 | f->secret_timer.expires = jiffies + f->secret_interval; |
68 | add_timer(&f->secret_timer); |
69 | } |
70 | EXPORT_SYMBOL(inet_frags_init); |
71 | |
72 | void inet_frags_init_net(struct netns_frags *nf) |
73 | { |
74 | nf->nqueues = 0; |
75 | atomic_set(&nf->mem, 0); |
76 | INIT_LIST_HEAD(&nf->lru_list); |
77 | } |
78 | EXPORT_SYMBOL(inet_frags_init_net); |
79 | |
80 | void inet_frags_fini(struct inet_frags *f) |
81 | { |
82 | del_timer(&f->secret_timer); |
83 | } |
84 | EXPORT_SYMBOL(inet_frags_fini); |
85 | |
86 | void inet_frags_exit_net(struct netns_frags *nf, struct inet_frags *f) |
87 | { |
88 | nf->low_thresh = 0; |
89 | |
90 | local_bh_disable(); |
91 | inet_frag_evictor(nf, f); |
92 | local_bh_enable(); |
93 | } |
94 | EXPORT_SYMBOL(inet_frags_exit_net); |
95 | |
96 | static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f) |
97 | { |
98 | write_lock(&f->lock); |
99 | hlist_del(&fq->list); |
100 | list_del(&fq->lru_list); |
101 | fq->net->nqueues--; |
102 | write_unlock(&f->lock); |
103 | } |
104 | |
105 | void inet_frag_kill(struct inet_frag_queue *fq, struct inet_frags *f) |
106 | { |
107 | if (del_timer(&fq->timer)) |
108 | atomic_dec(&fq->refcnt); |
109 | |
110 | if (!(fq->last_in & INET_FRAG_COMPLETE)) { |
111 | fq_unlink(fq, f); |
112 | atomic_dec(&fq->refcnt); |
113 | fq->last_in |= INET_FRAG_COMPLETE; |
114 | } |
115 | } |
116 | |
117 | EXPORT_SYMBOL(inet_frag_kill); |
118 | |
119 | static inline void frag_kfree_skb(struct netns_frags *nf, struct inet_frags *f, |
120 | struct sk_buff *skb, int *work) |
121 | { |
122 | if (work) |
123 | *work -= skb->truesize; |
124 | |
125 | atomic_sub(skb->truesize, &nf->mem); |
126 | if (f->skb_free) |
127 | f->skb_free(skb); |
128 | kfree_skb(skb); |
129 | } |
130 | |
131 | void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f, |
132 | int *work) |
133 | { |
134 | struct sk_buff *fp; |
135 | struct netns_frags *nf; |
136 | |
137 | WARN_ON(!(q->last_in & INET_FRAG_COMPLETE)); |
138 | WARN_ON(del_timer(&q->timer) != 0); |
139 | |
140 | /* Release all fragment data. */ |
141 | fp = q->fragments; |
142 | nf = q->net; |
143 | while (fp) { |
144 | struct sk_buff *xp = fp->next; |
145 | |
146 | frag_kfree_skb(nf, f, fp, work); |
147 | fp = xp; |
148 | } |
149 | |
150 | if (work) |
151 | *work -= f->qsize; |
152 | atomic_sub(f->qsize, &nf->mem); |
153 | |
154 | if (f->destructor) |
155 | f->destructor(q); |
156 | kfree(q); |
157 | |
158 | } |
159 | EXPORT_SYMBOL(inet_frag_destroy); |
160 | |
161 | int inet_frag_evictor(struct netns_frags *nf, struct inet_frags *f) |
162 | { |
163 | struct inet_frag_queue *q; |
164 | int work, evicted = 0; |
165 | |
166 | work = atomic_read(&nf->mem) - nf->low_thresh; |
167 | while (work > 0) { |
168 | read_lock(&f->lock); |
169 | if (list_empty(&nf->lru_list)) { |
170 | read_unlock(&f->lock); |
171 | break; |
172 | } |
173 | |
174 | q = list_first_entry(&nf->lru_list, |
175 | struct inet_frag_queue, lru_list); |
176 | atomic_inc(&q->refcnt); |
177 | read_unlock(&f->lock); |
178 | |
179 | spin_lock(&q->lock); |
180 | if (!(q->last_in & INET_FRAG_COMPLETE)) |
181 | inet_frag_kill(q, f); |
182 | spin_unlock(&q->lock); |
183 | |
184 | if (atomic_dec_and_test(&q->refcnt)) |
185 | inet_frag_destroy(q, f, &work); |
186 | evicted++; |
187 | } |
188 | |
189 | return evicted; |
190 | } |
191 | EXPORT_SYMBOL(inet_frag_evictor); |
192 | |
193 | static struct inet_frag_queue *inet_frag_intern(struct netns_frags *nf, |
194 | struct inet_frag_queue *qp_in, struct inet_frags *f, |
195 | void *arg) |
196 | { |
197 | struct inet_frag_queue *qp; |
198 | #ifdef CONFIG_SMP |
199 | struct hlist_node *n; |
200 | #endif |
201 | unsigned int hash; |
202 | |
203 | write_lock(&f->lock); |
204 | /* |
205 | * While we stayed w/o the lock other CPU could update |
206 | * the rnd seed, so we need to re-calculate the hash |
207 | * chain. Fortunatelly the qp_in can be used to get one. |
208 | */ |
209 | hash = f->hashfn(qp_in); |
210 | #ifdef CONFIG_SMP |
211 | /* With SMP race we have to recheck hash table, because |
212 | * such entry could be created on other cpu, while we |
213 | * promoted read lock to write lock. |
214 | */ |
215 | hlist_for_each_entry(qp, n, &f->hash[hash], list) { |
216 | if (qp->net == nf && f->match(qp, arg)) { |
217 | atomic_inc(&qp->refcnt); |
218 | write_unlock(&f->lock); |
219 | qp_in->last_in |= INET_FRAG_COMPLETE; |
220 | inet_frag_put(qp_in, f); |
221 | return qp; |
222 | } |
223 | } |
224 | #endif |
225 | qp = qp_in; |
226 | if (!mod_timer(&qp->timer, jiffies + nf->timeout)) |
227 | atomic_inc(&qp->refcnt); |
228 | |
229 | atomic_inc(&qp->refcnt); |
230 | hlist_add_head(&qp->list, &f->hash[hash]); |
231 | list_add_tail(&qp->lru_list, &nf->lru_list); |
232 | nf->nqueues++; |
233 | write_unlock(&f->lock); |
234 | return qp; |
235 | } |
236 | |
237 | static struct inet_frag_queue *inet_frag_alloc(struct netns_frags *nf, |
238 | struct inet_frags *f, void *arg) |
239 | { |
240 | struct inet_frag_queue *q; |
241 | |
242 | q = kzalloc(f->qsize, GFP_ATOMIC); |
243 | if (q == NULL) |
244 | return NULL; |
245 | |
246 | f->constructor(q, arg); |
247 | atomic_add(f->qsize, &nf->mem); |
248 | setup_timer(&q->timer, f->frag_expire, (unsigned long)q); |
249 | spin_lock_init(&q->lock); |
250 | atomic_set(&q->refcnt, 1); |
251 | q->net = nf; |
252 | |
253 | return q; |
254 | } |
255 | |
256 | static struct inet_frag_queue *inet_frag_create(struct netns_frags *nf, |
257 | struct inet_frags *f, void *arg) |
258 | { |
259 | struct inet_frag_queue *q; |
260 | |
261 | q = inet_frag_alloc(nf, f, arg); |
262 | if (q == NULL) |
263 | return NULL; |
264 | |
265 | return inet_frag_intern(nf, q, f, arg); |
266 | } |
267 | |
268 | struct inet_frag_queue *inet_frag_find(struct netns_frags *nf, |
269 | struct inet_frags *f, void *key, unsigned int hash) |
270 | __releases(&f->lock) |
271 | { |
272 | struct inet_frag_queue *q; |
273 | struct hlist_node *n; |
274 | |
275 | hlist_for_each_entry(q, n, &f->hash[hash], list) { |
276 | if (q->net == nf && f->match(q, key)) { |
277 | atomic_inc(&q->refcnt); |
278 | read_unlock(&f->lock); |
279 | return q; |
280 | } |
281 | } |
282 | read_unlock(&f->lock); |
283 | |
284 | return inet_frag_create(nf, f, key); |
285 | } |
286 | EXPORT_SYMBOL(inet_frag_find); |
287 |
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