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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