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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// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * inet fragments management
4 *
5 * Authors: Pavel Emelyanov <xemul@openvz.org>
6 * Started as consolidation of ipv4/ip_fragment.c,
7 * ipv6/reassembly. and ipv6 nf conntrack reassembly
8 */
9
10#include <linux/list.h>
11#include <linux/spinlock.h>
12#include <linux/module.h>
13#include <linux/timer.h>
14#include <linux/mm.h>
15#include <linux/random.h>
16#include <linux/skbuff.h>
17#include <linux/rtnetlink.h>
18#include <linux/slab.h>
19#include <linux/rhashtable.h>
20
21#include <net/sock.h>
22#include <net/inet_frag.h>
23#include <net/inet_ecn.h>
24#include <net/ip.h>
25#include <net/ipv6.h>
26
27#include "../core/sock_destructor.h"
28
29/* Use skb->cb to track consecutive/adjacent fragments coming at
30 * the end of the queue. Nodes in the rb-tree queue will
31 * contain "runs" of one or more adjacent fragments.
32 *
33 * Invariants:
34 * - next_frag is NULL at the tail of a "run";
35 * - the head of a "run" has the sum of all fragment lengths in frag_run_len.
36 */
37struct ipfrag_skb_cb {
38 union {
39 struct inet_skb_parm h4;
40 struct inet6_skb_parm h6;
41 };
42 struct sk_buff *next_frag;
43 int frag_run_len;
44 int ip_defrag_offset;
45};
46
47#define FRAG_CB(skb) ((struct ipfrag_skb_cb *)((skb)->cb))
48
49static void fragcb_clear(struct sk_buff *skb)
50{
51 RB_CLEAR_NODE(&skb->rbnode);
52 FRAG_CB(skb)->next_frag = NULL;
53 FRAG_CB(skb)->frag_run_len = skb->len;
54}
55
56/* Append skb to the last "run". */
57static void fragrun_append_to_last(struct inet_frag_queue *q,
58 struct sk_buff *skb)
59{
60 fragcb_clear(skb);
61
62 FRAG_CB(q->last_run_head)->frag_run_len += skb->len;
63 FRAG_CB(q->fragments_tail)->next_frag = skb;
64 q->fragments_tail = skb;
65}
66
67/* Create a new "run" with the skb. */
68static void fragrun_create(struct inet_frag_queue *q, struct sk_buff *skb)
69{
70 BUILD_BUG_ON(sizeof(struct ipfrag_skb_cb) > sizeof(skb->cb));
71 fragcb_clear(skb);
72
73 if (q->last_run_head)
74 rb_link_node(&skb->rbnode, &q->last_run_head->rbnode,
75 &q->last_run_head->rbnode.rb_right);
76 else
77 rb_link_node(&skb->rbnode, NULL, &q->rb_fragments.rb_node);
78 rb_insert_color(&skb->rbnode, &q->rb_fragments);
79
80 q->fragments_tail = skb;
81 q->last_run_head = skb;
82}
83
84/* Given the OR values of all fragments, apply RFC 3168 5.3 requirements
85 * Value : 0xff if frame should be dropped.
86 * 0 or INET_ECN_CE value, to be ORed in to final iph->tos field
87 */
88const u8 ip_frag_ecn_table[16] = {
89 /* at least one fragment had CE, and others ECT_0 or ECT_1 */
90 [IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0] = INET_ECN_CE,
91 [IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1] = INET_ECN_CE,
92 [IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = INET_ECN_CE,
93
94 /* invalid combinations : drop frame */
95 [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE] = 0xff,
96 [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0] = 0xff,
97 [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_1] = 0xff,
98 [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff,
99 [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0] = 0xff,
100 [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1] = 0xff,
101 [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff,
102};
103EXPORT_SYMBOL(ip_frag_ecn_table);
104
105int inet_frags_init(struct inet_frags *f)
106{
107 f->frags_cachep = kmem_cache_create(f->frags_cache_name, f->qsize, 0, 0,
108 NULL);
109 if (!f->frags_cachep)
110 return -ENOMEM;
111
112 refcount_set(&f->refcnt, 1);
113 init_completion(&f->completion);
114 return 0;
115}
116EXPORT_SYMBOL(inet_frags_init);
117
118void inet_frags_fini(struct inet_frags *f)
119{
120 if (refcount_dec_and_test(&f->refcnt))
121 complete(&f->completion);
122
123 wait_for_completion(&f->completion);
124
125 kmem_cache_destroy(f->frags_cachep);
126 f->frags_cachep = NULL;
127}
128EXPORT_SYMBOL(inet_frags_fini);
129
130/* called from rhashtable_free_and_destroy() at netns_frags dismantle */
131static void inet_frags_free_cb(void *ptr, void *arg)
132{
133 struct inet_frag_queue *fq = ptr;
134 int count;
135
136 count = del_timer_sync(&fq->timer) ? 1 : 0;
137
138 spin_lock_bh(&fq->lock);
139 fq->flags |= INET_FRAG_DROP;
140 if (!(fq->flags & INET_FRAG_COMPLETE)) {
141 fq->flags |= INET_FRAG_COMPLETE;
142 count++;
143 } else if (fq->flags & INET_FRAG_HASH_DEAD) {
144 count++;
145 }
146 spin_unlock_bh(&fq->lock);
147
148 if (refcount_sub_and_test(count, &fq->refcnt))
149 inet_frag_destroy(fq);
150}
151
152static LLIST_HEAD(fqdir_free_list);
153
154static void fqdir_free_fn(struct work_struct *work)
155{
156 struct llist_node *kill_list;
157 struct fqdir *fqdir, *tmp;
158 struct inet_frags *f;
159
160 /* Atomically snapshot the list of fqdirs to free */
161 kill_list = llist_del_all(&fqdir_free_list);
162
163 /* We need to make sure all ongoing call_rcu(..., inet_frag_destroy_rcu)
164 * have completed, since they need to dereference fqdir.
165 * Would it not be nice to have kfree_rcu_barrier() ? :)
166 */
167 rcu_barrier();
168
169 llist_for_each_entry_safe(fqdir, tmp, kill_list, free_list) {
170 f = fqdir->f;
171 if (refcount_dec_and_test(&f->refcnt))
172 complete(&f->completion);
173
174 kfree(fqdir);
175 }
176}
177
178static DECLARE_DELAYED_WORK(fqdir_free_work, fqdir_free_fn);
179
180static void fqdir_work_fn(struct work_struct *work)
181{
182 struct fqdir *fqdir = container_of(work, struct fqdir, destroy_work);
183
184 rhashtable_free_and_destroy(&fqdir->rhashtable, inet_frags_free_cb, NULL);
185
186 if (llist_add(&fqdir->free_list, &fqdir_free_list))
187 queue_delayed_work(system_wq, &fqdir_free_work, HZ);
188}
189
190int fqdir_init(struct fqdir **fqdirp, struct inet_frags *f, struct net *net)
191{
192 struct fqdir *fqdir = kzalloc(sizeof(*fqdir), GFP_KERNEL);
193 int res;
194
195 if (!fqdir)
196 return -ENOMEM;
197 fqdir->f = f;
198 fqdir->net = net;
199 res = rhashtable_init(&fqdir->rhashtable, &fqdir->f->rhash_params);
200 if (res < 0) {
201 kfree(fqdir);
202 return res;
203 }
204 refcount_inc(&f->refcnt);
205 *fqdirp = fqdir;
206 return 0;
207}
208EXPORT_SYMBOL(fqdir_init);
209
210static struct workqueue_struct *inet_frag_wq;
211
212static int __init inet_frag_wq_init(void)
213{
214 inet_frag_wq = create_workqueue("inet_frag_wq");
215 if (!inet_frag_wq)
216 panic("Could not create inet frag workq");
217 return 0;
218}
219
220pure_initcall(inet_frag_wq_init);
221
222void fqdir_exit(struct fqdir *fqdir)
223{
224 INIT_WORK(&fqdir->destroy_work, fqdir_work_fn);
225 queue_work(inet_frag_wq, &fqdir->destroy_work);
226}
227EXPORT_SYMBOL(fqdir_exit);
228
229void inet_frag_kill(struct inet_frag_queue *fq)
230{
231 if (del_timer(&fq->timer))
232 refcount_dec(&fq->refcnt);
233
234 if (!(fq->flags & INET_FRAG_COMPLETE)) {
235 struct fqdir *fqdir = fq->fqdir;
236
237 fq->flags |= INET_FRAG_COMPLETE;
238 rcu_read_lock();
239 /* The RCU read lock provides a memory barrier
240 * guaranteeing that if fqdir->dead is false then
241 * the hash table destruction will not start until
242 * after we unlock. Paired with fqdir_pre_exit().
243 */
244 if (!READ_ONCE(fqdir->dead)) {
245 rhashtable_remove_fast(&fqdir->rhashtable, &fq->node,
246 fqdir->f->rhash_params);
247 refcount_dec(&fq->refcnt);
248 } else {
249 fq->flags |= INET_FRAG_HASH_DEAD;
250 }
251 rcu_read_unlock();
252 }
253}
254EXPORT_SYMBOL(inet_frag_kill);
255
256static void inet_frag_destroy_rcu(struct rcu_head *head)
257{
258 struct inet_frag_queue *q = container_of(head, struct inet_frag_queue,
259 rcu);
260 struct inet_frags *f = q->fqdir->f;
261
262 if (f->destructor)
263 f->destructor(q);
264 kmem_cache_free(f->frags_cachep, q);
265}
266
267unsigned int inet_frag_rbtree_purge(struct rb_root *root,
268 enum skb_drop_reason reason)
269{
270 struct rb_node *p = rb_first(root);
271 unsigned int sum = 0;
272
273 while (p) {
274 struct sk_buff *skb = rb_entry(p, struct sk_buff, rbnode);
275
276 p = rb_next(p);
277 rb_erase(&skb->rbnode, root);
278 while (skb) {
279 struct sk_buff *next = FRAG_CB(skb)->next_frag;
280
281 sum += skb->truesize;
282 kfree_skb_reason(skb, reason);
283 skb = next;
284 }
285 }
286 return sum;
287}
288EXPORT_SYMBOL(inet_frag_rbtree_purge);
289
290void inet_frag_destroy(struct inet_frag_queue *q)
291{
292 unsigned int sum, sum_truesize = 0;
293 enum skb_drop_reason reason;
294 struct inet_frags *f;
295 struct fqdir *fqdir;
296
297 WARN_ON(!(q->flags & INET_FRAG_COMPLETE));
298 reason = (q->flags & INET_FRAG_DROP) ?
299 SKB_DROP_REASON_FRAG_REASM_TIMEOUT :
300 SKB_CONSUMED;
301 WARN_ON(del_timer(&q->timer) != 0);
302
303 /* Release all fragment data. */
304 fqdir = q->fqdir;
305 f = fqdir->f;
306 sum_truesize = inet_frag_rbtree_purge(&q->rb_fragments, reason);
307 sum = sum_truesize + f->qsize;
308
309 call_rcu(&q->rcu, inet_frag_destroy_rcu);
310
311 sub_frag_mem_limit(fqdir, sum);
312}
313EXPORT_SYMBOL(inet_frag_destroy);
314
315static struct inet_frag_queue *inet_frag_alloc(struct fqdir *fqdir,
316 struct inet_frags *f,
317 void *arg)
318{
319 struct inet_frag_queue *q;
320
321 q = kmem_cache_zalloc(f->frags_cachep, GFP_ATOMIC);
322 if (!q)
323 return NULL;
324
325 q->fqdir = fqdir;
326 f->constructor(q, arg);
327 add_frag_mem_limit(fqdir, f->qsize);
328
329 timer_setup(&q->timer, f->frag_expire, 0);
330 spin_lock_init(&q->lock);
331 refcount_set(&q->refcnt, 3);
332
333 return q;
334}
335
336static struct inet_frag_queue *inet_frag_create(struct fqdir *fqdir,
337 void *arg,
338 struct inet_frag_queue **prev)
339{
340 struct inet_frags *f = fqdir->f;
341 struct inet_frag_queue *q;
342
343 q = inet_frag_alloc(fqdir, f, arg);
344 if (!q) {
345 *prev = ERR_PTR(-ENOMEM);
346 return NULL;
347 }
348 mod_timer(&q->timer, jiffies + fqdir->timeout);
349
350 *prev = rhashtable_lookup_get_insert_key(&fqdir->rhashtable, &q->key,
351 &q->node, f->rhash_params);
352 if (*prev) {
353 q->flags |= INET_FRAG_COMPLETE;
354 inet_frag_kill(q);
355 inet_frag_destroy(q);
356 return NULL;
357 }
358 return q;
359}
360
361/* TODO : call from rcu_read_lock() and no longer use refcount_inc_not_zero() */
362struct inet_frag_queue *inet_frag_find(struct fqdir *fqdir, void *key)
363{
364 /* This pairs with WRITE_ONCE() in fqdir_pre_exit(). */
365 long high_thresh = READ_ONCE(fqdir->high_thresh);
366 struct inet_frag_queue *fq = NULL, *prev;
367
368 if (!high_thresh || frag_mem_limit(fqdir) > high_thresh)
369 return NULL;
370
371 rcu_read_lock();
372
373 prev = rhashtable_lookup(&fqdir->rhashtable, key, fqdir->f->rhash_params);
374 if (!prev)
375 fq = inet_frag_create(fqdir, key, &prev);
376 if (!IS_ERR_OR_NULL(prev)) {
377 fq = prev;
378 if (!refcount_inc_not_zero(&fq->refcnt))
379 fq = NULL;
380 }
381 rcu_read_unlock();
382 return fq;
383}
384EXPORT_SYMBOL(inet_frag_find);
385
386int inet_frag_queue_insert(struct inet_frag_queue *q, struct sk_buff *skb,
387 int offset, int end)
388{
389 struct sk_buff *last = q->fragments_tail;
390
391 /* RFC5722, Section 4, amended by Errata ID : 3089
392 * When reassembling an IPv6 datagram, if
393 * one or more its constituent fragments is determined to be an
394 * overlapping fragment, the entire datagram (and any constituent
395 * fragments) MUST be silently discarded.
396 *
397 * Duplicates, however, should be ignored (i.e. skb dropped, but the
398 * queue/fragments kept for later reassembly).
399 */
400 if (!last)
401 fragrun_create(q, skb); /* First fragment. */
402 else if (FRAG_CB(last)->ip_defrag_offset + last->len < end) {
403 /* This is the common case: skb goes to the end. */
404 /* Detect and discard overlaps. */
405 if (offset < FRAG_CB(last)->ip_defrag_offset + last->len)
406 return IPFRAG_OVERLAP;
407 if (offset == FRAG_CB(last)->ip_defrag_offset + last->len)
408 fragrun_append_to_last(q, skb);
409 else
410 fragrun_create(q, skb);
411 } else {
412 /* Binary search. Note that skb can become the first fragment,
413 * but not the last (covered above).
414 */
415 struct rb_node **rbn, *parent;
416
417 rbn = &q->rb_fragments.rb_node;
418 do {
419 struct sk_buff *curr;
420 int curr_run_end;
421
422 parent = *rbn;
423 curr = rb_to_skb(parent);
424 curr_run_end = FRAG_CB(curr)->ip_defrag_offset +
425 FRAG_CB(curr)->frag_run_len;
426 if (end <= FRAG_CB(curr)->ip_defrag_offset)
427 rbn = &parent->rb_left;
428 else if (offset >= curr_run_end)
429 rbn = &parent->rb_right;
430 else if (offset >= FRAG_CB(curr)->ip_defrag_offset &&
431 end <= curr_run_end)
432 return IPFRAG_DUP;
433 else
434 return IPFRAG_OVERLAP;
435 } while (*rbn);
436 /* Here we have parent properly set, and rbn pointing to
437 * one of its NULL left/right children. Insert skb.
438 */
439 fragcb_clear(skb);
440 rb_link_node(&skb->rbnode, parent, rbn);
441 rb_insert_color(&skb->rbnode, &q->rb_fragments);
442 }
443
444 FRAG_CB(skb)->ip_defrag_offset = offset;
445
446 return IPFRAG_OK;
447}
448EXPORT_SYMBOL(inet_frag_queue_insert);
449
450void *inet_frag_reasm_prepare(struct inet_frag_queue *q, struct sk_buff *skb,
451 struct sk_buff *parent)
452{
453 struct sk_buff *fp, *head = skb_rb_first(&q->rb_fragments);
454 void (*destructor)(struct sk_buff *);
455 unsigned int orig_truesize = 0;
456 struct sk_buff **nextp = NULL;
457 struct sock *sk = skb->sk;
458 int delta;
459
460 if (sk && is_skb_wmem(skb)) {
461 /* TX: skb->sk might have been passed as argument to
462 * dst->output and must remain valid until tx completes.
463 *
464 * Move sk to reassembled skb and fix up wmem accounting.
465 */
466 orig_truesize = skb->truesize;
467 destructor = skb->destructor;
468 }
469
470 if (head != skb) {
471 fp = skb_clone(skb, GFP_ATOMIC);
472 if (!fp) {
473 head = skb;
474 goto out_restore_sk;
475 }
476 FRAG_CB(fp)->next_frag = FRAG_CB(skb)->next_frag;
477 if (RB_EMPTY_NODE(&skb->rbnode))
478 FRAG_CB(parent)->next_frag = fp;
479 else
480 rb_replace_node(&skb->rbnode, &fp->rbnode,
481 &q->rb_fragments);
482 if (q->fragments_tail == skb)
483 q->fragments_tail = fp;
484
485 if (orig_truesize) {
486 /* prevent skb_morph from releasing sk */
487 skb->sk = NULL;
488 skb->destructor = NULL;
489 }
490 skb_morph(skb, head);
491 FRAG_CB(skb)->next_frag = FRAG_CB(head)->next_frag;
492 rb_replace_node(&head->rbnode, &skb->rbnode,
493 &q->rb_fragments);
494 consume_skb(head);
495 head = skb;
496 }
497 WARN_ON(FRAG_CB(head)->ip_defrag_offset != 0);
498
499 delta = -head->truesize;
500
501 /* Head of list must not be cloned. */
502 if (skb_unclone(head, GFP_ATOMIC))
503 goto out_restore_sk;
504
505 delta += head->truesize;
506 if (delta)
507 add_frag_mem_limit(q->fqdir, delta);
508
509 /* If the first fragment is fragmented itself, we split
510 * it to two chunks: the first with data and paged part
511 * and the second, holding only fragments.
512 */
513 if (skb_has_frag_list(head)) {
514 struct sk_buff *clone;
515 int i, plen = 0;
516
517 clone = alloc_skb(0, GFP_ATOMIC);
518 if (!clone)
519 goto out_restore_sk;
520 skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list;
521 skb_frag_list_init(head);
522 for (i = 0; i < skb_shinfo(head)->nr_frags; i++)
523 plen += skb_frag_size(&skb_shinfo(head)->frags[i]);
524 clone->data_len = head->data_len - plen;
525 clone->len = clone->data_len;
526 head->truesize += clone->truesize;
527 clone->csum = 0;
528 clone->ip_summed = head->ip_summed;
529 add_frag_mem_limit(q->fqdir, clone->truesize);
530 skb_shinfo(head)->frag_list = clone;
531 nextp = &clone->next;
532 } else {
533 nextp = &skb_shinfo(head)->frag_list;
534 }
535
536out_restore_sk:
537 if (orig_truesize) {
538 int ts_delta = head->truesize - orig_truesize;
539
540 /* if this reassembled skb is fragmented later,
541 * fraglist skbs will get skb->sk assigned from head->sk,
542 * and each frag skb will be released via sock_wfree.
543 *
544 * Update sk_wmem_alloc.
545 */
546 head->sk = sk;
547 head->destructor = destructor;
548 refcount_add(ts_delta, &sk->sk_wmem_alloc);
549 }
550
551 return nextp;
552}
553EXPORT_SYMBOL(inet_frag_reasm_prepare);
554
555void inet_frag_reasm_finish(struct inet_frag_queue *q, struct sk_buff *head,
556 void *reasm_data, bool try_coalesce)
557{
558 struct sock *sk = is_skb_wmem(head) ? head->sk : NULL;
559 const unsigned int head_truesize = head->truesize;
560 struct sk_buff **nextp = reasm_data;
561 struct rb_node *rbn;
562 struct sk_buff *fp;
563 int sum_truesize;
564
565 skb_push(head, head->data - skb_network_header(head));
566
567 /* Traverse the tree in order, to build frag_list. */
568 fp = FRAG_CB(head)->next_frag;
569 rbn = rb_next(&head->rbnode);
570 rb_erase(&head->rbnode, &q->rb_fragments);
571
572 sum_truesize = head->truesize;
573 while (rbn || fp) {
574 /* fp points to the next sk_buff in the current run;
575 * rbn points to the next run.
576 */
577 /* Go through the current run. */
578 while (fp) {
579 struct sk_buff *next_frag = FRAG_CB(fp)->next_frag;
580 bool stolen;
581 int delta;
582
583 sum_truesize += fp->truesize;
584 if (head->ip_summed != fp->ip_summed)
585 head->ip_summed = CHECKSUM_NONE;
586 else if (head->ip_summed == CHECKSUM_COMPLETE)
587 head->csum = csum_add(head->csum, fp->csum);
588
589 if (try_coalesce && skb_try_coalesce(head, fp, &stolen,
590 &delta)) {
591 kfree_skb_partial(fp, stolen);
592 } else {
593 fp->prev = NULL;
594 memset(&fp->rbnode, 0, sizeof(fp->rbnode));
595 fp->sk = NULL;
596
597 head->data_len += fp->len;
598 head->len += fp->len;
599 head->truesize += fp->truesize;
600
601 *nextp = fp;
602 nextp = &fp->next;
603 }
604
605 fp = next_frag;
606 }
607 /* Move to the next run. */
608 if (rbn) {
609 struct rb_node *rbnext = rb_next(rbn);
610
611 fp = rb_to_skb(rbn);
612 rb_erase(rbn, &q->rb_fragments);
613 rbn = rbnext;
614 }
615 }
616 sub_frag_mem_limit(q->fqdir, sum_truesize);
617
618 *nextp = NULL;
619 skb_mark_not_on_list(head);
620 head->prev = NULL;
621 head->tstamp = q->stamp;
622 head->tstamp_type = q->tstamp_type;
623
624 if (sk)
625 refcount_add(sum_truesize - head_truesize, &sk->sk_wmem_alloc);
626}
627EXPORT_SYMBOL(inet_frag_reasm_finish);
628
629struct sk_buff *inet_frag_pull_head(struct inet_frag_queue *q)
630{
631 struct sk_buff *head, *skb;
632
633 head = skb_rb_first(&q->rb_fragments);
634 if (!head)
635 return NULL;
636 skb = FRAG_CB(head)->next_frag;
637 if (skb)
638 rb_replace_node(&head->rbnode, &skb->rbnode,
639 &q->rb_fragments);
640 else
641 rb_erase(&head->rbnode, &q->rb_fragments);
642 memset(&head->rbnode, 0, sizeof(head->rbnode));
643 barrier();
644
645 if (head == q->fragments_tail)
646 q->fragments_tail = NULL;
647
648 sub_frag_mem_limit(q->fqdir, head->truesize);
649
650 return head;
651}
652EXPORT_SYMBOL(inet_frag_pull_head);