Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * INET An implementation of the TCP/IP protocol suite for the LINUX | |
3 | * operating system. INET is implemented using the BSD Socket | |
4 | * interface as the means of communication with the user level. | |
5 | * | |
6 | * The IP fragmentation functionality. | |
e905a9ed | 7 | * |
1da177e4 LT |
8 | * Version: $Id: ip_fragment.c,v 1.59 2002/01/12 07:54:56 davem Exp $ |
9 | * | |
10 | * Authors: Fred N. van Kempen <waltje@uWalt.NL.Mugnet.ORG> | |
11 | * Alan Cox <Alan.Cox@linux.org> | |
12 | * | |
13 | * Fixes: | |
14 | * Alan Cox : Split from ip.c , see ip_input.c for history. | |
15 | * David S. Miller : Begin massive cleanup... | |
16 | * Andi Kleen : Add sysctls. | |
17 | * xxxx : Overlapfrag bug. | |
18 | * Ultima : ip_expire() kernel panic. | |
19 | * Bill Hawes : Frag accounting and evictor fixes. | |
20 | * John McDonald : 0 length frag bug. | |
21 | * Alexey Kuznetsov: SMP races, threading, cleanup. | |
22 | * Patrick McHardy : LRU queue of frag heads for evictor. | |
23 | */ | |
24 | ||
89cee8b1 | 25 | #include <linux/compiler.h> |
1da177e4 LT |
26 | #include <linux/module.h> |
27 | #include <linux/types.h> | |
28 | #include <linux/mm.h> | |
29 | #include <linux/jiffies.h> | |
30 | #include <linux/skbuff.h> | |
31 | #include <linux/list.h> | |
32 | #include <linux/ip.h> | |
33 | #include <linux/icmp.h> | |
34 | #include <linux/netdevice.h> | |
35 | #include <linux/jhash.h> | |
36 | #include <linux/random.h> | |
37 | #include <net/sock.h> | |
38 | #include <net/ip.h> | |
39 | #include <net/icmp.h> | |
40 | #include <net/checksum.h> | |
89cee8b1 | 41 | #include <net/inetpeer.h> |
1da177e4 LT |
42 | #include <linux/tcp.h> |
43 | #include <linux/udp.h> | |
44 | #include <linux/inet.h> | |
45 | #include <linux/netfilter_ipv4.h> | |
46 | ||
47 | /* NOTE. Logic of IP defragmentation is parallel to corresponding IPv6 | |
48 | * code now. If you change something here, _PLEASE_ update ipv6/reassembly.c | |
49 | * as well. Or notify me, at least. --ANK | |
50 | */ | |
51 | ||
52 | /* Fragment cache limits. We will commit 256K at one time. Should we | |
53 | * cross that limit we will prune down to 192K. This should cope with | |
54 | * even the most extreme cases without allowing an attacker to measurably | |
55 | * harm machine performance. | |
56 | */ | |
ab32ea5d BH |
57 | int sysctl_ipfrag_high_thresh __read_mostly = 256*1024; |
58 | int sysctl_ipfrag_low_thresh __read_mostly = 192*1024; | |
1da177e4 | 59 | |
ab32ea5d | 60 | int sysctl_ipfrag_max_dist __read_mostly = 64; |
89cee8b1 | 61 | |
1da177e4 LT |
62 | /* Important NOTE! Fragment queue must be destroyed before MSL expires. |
63 | * RFC791 is wrong proposing to prolongate timer each fragment arrival by TTL. | |
64 | */ | |
ab32ea5d | 65 | int sysctl_ipfrag_time __read_mostly = IP_FRAG_TIME; |
1da177e4 LT |
66 | |
67 | struct ipfrag_skb_cb | |
68 | { | |
69 | struct inet_skb_parm h; | |
70 | int offset; | |
71 | }; | |
72 | ||
73 | #define FRAG_CB(skb) ((struct ipfrag_skb_cb*)((skb)->cb)) | |
74 | ||
75 | /* Describe an entry in the "incomplete datagrams" queue. */ | |
76 | struct ipq { | |
e7c8a41e | 77 | struct hlist_node list; |
1da177e4 LT |
78 | struct list_head lru_list; /* lru list member */ |
79 | u32 user; | |
18277770 AV |
80 | __be32 saddr; |
81 | __be32 daddr; | |
82 | __be16 id; | |
1da177e4 LT |
83 | u8 protocol; |
84 | u8 last_in; | |
85 | #define COMPLETE 4 | |
86 | #define FIRST_IN 2 | |
87 | #define LAST_IN 1 | |
88 | ||
89 | struct sk_buff *fragments; /* linked list of received fragments */ | |
90 | int len; /* total length of original datagram */ | |
91 | int meat; | |
92 | spinlock_t lock; | |
93 | atomic_t refcnt; | |
94 | struct timer_list timer; /* when will this queue expire? */ | |
1da177e4 | 95 | struct timeval stamp; |
89cee8b1 HX |
96 | int iif; |
97 | unsigned int rid; | |
98 | struct inet_peer *peer; | |
1da177e4 LT |
99 | }; |
100 | ||
101 | /* Hash table. */ | |
102 | ||
103 | #define IPQ_HASHSZ 64 | |
104 | ||
105 | /* Per-bucket lock is easy to add now. */ | |
e7c8a41e | 106 | static struct hlist_head ipq_hash[IPQ_HASHSZ]; |
1da177e4 LT |
107 | static DEFINE_RWLOCK(ipfrag_lock); |
108 | static u32 ipfrag_hash_rnd; | |
109 | static LIST_HEAD(ipq_lru_list); | |
110 | int ip_frag_nqueues = 0; | |
111 | ||
112 | static __inline__ void __ipq_unlink(struct ipq *qp) | |
113 | { | |
e7c8a41e | 114 | hlist_del(&qp->list); |
1da177e4 LT |
115 | list_del(&qp->lru_list); |
116 | ip_frag_nqueues--; | |
117 | } | |
118 | ||
119 | static __inline__ void ipq_unlink(struct ipq *ipq) | |
120 | { | |
121 | write_lock(&ipfrag_lock); | |
122 | __ipq_unlink(ipq); | |
123 | write_unlock(&ipfrag_lock); | |
124 | } | |
125 | ||
18277770 | 126 | static unsigned int ipqhashfn(__be16 id, __be32 saddr, __be32 daddr, u8 prot) |
1da177e4 | 127 | { |
18277770 AV |
128 | return jhash_3words((__force u32)id << 16 | prot, |
129 | (__force u32)saddr, (__force u32)daddr, | |
1da177e4 LT |
130 | ipfrag_hash_rnd) & (IPQ_HASHSZ - 1); |
131 | } | |
132 | ||
133 | static struct timer_list ipfrag_secret_timer; | |
ab32ea5d | 134 | int sysctl_ipfrag_secret_interval __read_mostly = 10 * 60 * HZ; |
1da177e4 LT |
135 | |
136 | static void ipfrag_secret_rebuild(unsigned long dummy) | |
137 | { | |
138 | unsigned long now = jiffies; | |
139 | int i; | |
140 | ||
141 | write_lock(&ipfrag_lock); | |
142 | get_random_bytes(&ipfrag_hash_rnd, sizeof(u32)); | |
143 | for (i = 0; i < IPQ_HASHSZ; i++) { | |
144 | struct ipq *q; | |
e7c8a41e | 145 | struct hlist_node *p, *n; |
1da177e4 | 146 | |
e7c8a41e | 147 | hlist_for_each_entry_safe(q, p, n, &ipq_hash[i], list) { |
1da177e4 LT |
148 | unsigned int hval = ipqhashfn(q->id, q->saddr, |
149 | q->daddr, q->protocol); | |
150 | ||
151 | if (hval != i) { | |
e7c8a41e | 152 | hlist_del(&q->list); |
1da177e4 LT |
153 | |
154 | /* Relink to new hash chain. */ | |
e7c8a41e | 155 | hlist_add_head(&q->list, &ipq_hash[hval]); |
1da177e4 | 156 | } |
1da177e4 LT |
157 | } |
158 | } | |
159 | write_unlock(&ipfrag_lock); | |
160 | ||
161 | mod_timer(&ipfrag_secret_timer, now + sysctl_ipfrag_secret_interval); | |
162 | } | |
163 | ||
164 | atomic_t ip_frag_mem = ATOMIC_INIT(0); /* Memory used for fragments */ | |
165 | ||
166 | /* Memory Tracking Functions. */ | |
167 | static __inline__ void frag_kfree_skb(struct sk_buff *skb, int *work) | |
168 | { | |
169 | if (work) | |
170 | *work -= skb->truesize; | |
171 | atomic_sub(skb->truesize, &ip_frag_mem); | |
172 | kfree_skb(skb); | |
173 | } | |
174 | ||
175 | static __inline__ void frag_free_queue(struct ipq *qp, int *work) | |
176 | { | |
177 | if (work) | |
178 | *work -= sizeof(struct ipq); | |
179 | atomic_sub(sizeof(struct ipq), &ip_frag_mem); | |
180 | kfree(qp); | |
181 | } | |
182 | ||
183 | static __inline__ struct ipq *frag_alloc_queue(void) | |
184 | { | |
185 | struct ipq *qp = kmalloc(sizeof(struct ipq), GFP_ATOMIC); | |
186 | ||
187 | if(!qp) | |
188 | return NULL; | |
189 | atomic_add(sizeof(struct ipq), &ip_frag_mem); | |
190 | return qp; | |
191 | } | |
192 | ||
193 | ||
194 | /* Destruction primitives. */ | |
195 | ||
196 | /* Complete destruction of ipq. */ | |
197 | static void ip_frag_destroy(struct ipq *qp, int *work) | |
198 | { | |
199 | struct sk_buff *fp; | |
200 | ||
201 | BUG_TRAP(qp->last_in&COMPLETE); | |
202 | BUG_TRAP(del_timer(&qp->timer) == 0); | |
203 | ||
89cee8b1 HX |
204 | if (qp->peer) |
205 | inet_putpeer(qp->peer); | |
206 | ||
1da177e4 LT |
207 | /* Release all fragment data. */ |
208 | fp = qp->fragments; | |
209 | while (fp) { | |
210 | struct sk_buff *xp = fp->next; | |
211 | ||
212 | frag_kfree_skb(fp, work); | |
213 | fp = xp; | |
214 | } | |
215 | ||
216 | /* Finally, release the queue descriptor itself. */ | |
217 | frag_free_queue(qp, work); | |
218 | } | |
219 | ||
220 | static __inline__ void ipq_put(struct ipq *ipq, int *work) | |
221 | { | |
222 | if (atomic_dec_and_test(&ipq->refcnt)) | |
223 | ip_frag_destroy(ipq, work); | |
224 | } | |
225 | ||
226 | /* Kill ipq entry. It is not destroyed immediately, | |
227 | * because caller (and someone more) holds reference count. | |
228 | */ | |
229 | static void ipq_kill(struct ipq *ipq) | |
230 | { | |
231 | if (del_timer(&ipq->timer)) | |
232 | atomic_dec(&ipq->refcnt); | |
233 | ||
234 | if (!(ipq->last_in & COMPLETE)) { | |
235 | ipq_unlink(ipq); | |
236 | atomic_dec(&ipq->refcnt); | |
237 | ipq->last_in |= COMPLETE; | |
238 | } | |
239 | } | |
240 | ||
e905a9ed | 241 | /* Memory limiting on fragments. Evictor trashes the oldest |
1da177e4 LT |
242 | * fragment queue until we are back under the threshold. |
243 | */ | |
244 | static void ip_evictor(void) | |
245 | { | |
246 | struct ipq *qp; | |
247 | struct list_head *tmp; | |
248 | int work; | |
249 | ||
250 | work = atomic_read(&ip_frag_mem) - sysctl_ipfrag_low_thresh; | |
251 | if (work <= 0) | |
252 | return; | |
253 | ||
254 | while (work > 0) { | |
255 | read_lock(&ipfrag_lock); | |
256 | if (list_empty(&ipq_lru_list)) { | |
257 | read_unlock(&ipfrag_lock); | |
258 | return; | |
259 | } | |
260 | tmp = ipq_lru_list.next; | |
261 | qp = list_entry(tmp, struct ipq, lru_list); | |
262 | atomic_inc(&qp->refcnt); | |
263 | read_unlock(&ipfrag_lock); | |
264 | ||
265 | spin_lock(&qp->lock); | |
266 | if (!(qp->last_in&COMPLETE)) | |
267 | ipq_kill(qp); | |
268 | spin_unlock(&qp->lock); | |
269 | ||
270 | ipq_put(qp, &work); | |
271 | IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); | |
272 | } | |
273 | } | |
274 | ||
275 | /* | |
276 | * Oops, a fragment queue timed out. Kill it and send an ICMP reply. | |
277 | */ | |
278 | static void ip_expire(unsigned long arg) | |
279 | { | |
280 | struct ipq *qp = (struct ipq *) arg; | |
281 | ||
282 | spin_lock(&qp->lock); | |
283 | ||
284 | if (qp->last_in & COMPLETE) | |
285 | goto out; | |
286 | ||
287 | ipq_kill(qp); | |
288 | ||
289 | IP_INC_STATS_BH(IPSTATS_MIB_REASMTIMEOUT); | |
290 | IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); | |
291 | ||
292 | if ((qp->last_in&FIRST_IN) && qp->fragments != NULL) { | |
293 | struct sk_buff *head = qp->fragments; | |
294 | /* Send an ICMP "Fragment Reassembly Timeout" message. */ | |
295 | if ((head->dev = dev_get_by_index(qp->iif)) != NULL) { | |
296 | icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0); | |
297 | dev_put(head->dev); | |
298 | } | |
299 | } | |
300 | out: | |
301 | spin_unlock(&qp->lock); | |
302 | ipq_put(qp, NULL); | |
303 | } | |
304 | ||
305 | /* Creation primitives. */ | |
306 | ||
55c0022e | 307 | static struct ipq *ip_frag_intern(struct ipq *qp_in) |
1da177e4 LT |
308 | { |
309 | struct ipq *qp; | |
e7c8a41e YK |
310 | #ifdef CONFIG_SMP |
311 | struct hlist_node *n; | |
312 | #endif | |
55c0022e DM |
313 | unsigned int hash; |
314 | ||
1da177e4 | 315 | write_lock(&ipfrag_lock); |
55c0022e DM |
316 | hash = ipqhashfn(qp_in->id, qp_in->saddr, qp_in->daddr, |
317 | qp_in->protocol); | |
1da177e4 LT |
318 | #ifdef CONFIG_SMP |
319 | /* With SMP race we have to recheck hash table, because | |
320 | * such entry could be created on other cpu, while we | |
321 | * promoted read lock to write lock. | |
322 | */ | |
e7c8a41e | 323 | hlist_for_each_entry(qp, n, &ipq_hash[hash], list) { |
1da177e4 LT |
324 | if(qp->id == qp_in->id && |
325 | qp->saddr == qp_in->saddr && | |
326 | qp->daddr == qp_in->daddr && | |
327 | qp->protocol == qp_in->protocol && | |
328 | qp->user == qp_in->user) { | |
329 | atomic_inc(&qp->refcnt); | |
330 | write_unlock(&ipfrag_lock); | |
331 | qp_in->last_in |= COMPLETE; | |
332 | ipq_put(qp_in, NULL); | |
333 | return qp; | |
334 | } | |
335 | } | |
336 | #endif | |
337 | qp = qp_in; | |
338 | ||
339 | if (!mod_timer(&qp->timer, jiffies + sysctl_ipfrag_time)) | |
340 | atomic_inc(&qp->refcnt); | |
341 | ||
342 | atomic_inc(&qp->refcnt); | |
e7c8a41e | 343 | hlist_add_head(&qp->list, &ipq_hash[hash]); |
1da177e4 LT |
344 | INIT_LIST_HEAD(&qp->lru_list); |
345 | list_add_tail(&qp->lru_list, &ipq_lru_list); | |
346 | ip_frag_nqueues++; | |
347 | write_unlock(&ipfrag_lock); | |
348 | return qp; | |
349 | } | |
350 | ||
351 | /* Add an entry to the 'ipq' queue for a newly received IP datagram. */ | |
55c0022e | 352 | static struct ipq *ip_frag_create(struct iphdr *iph, u32 user) |
1da177e4 LT |
353 | { |
354 | struct ipq *qp; | |
355 | ||
356 | if ((qp = frag_alloc_queue()) == NULL) | |
357 | goto out_nomem; | |
358 | ||
359 | qp->protocol = iph->protocol; | |
360 | qp->last_in = 0; | |
361 | qp->id = iph->id; | |
362 | qp->saddr = iph->saddr; | |
363 | qp->daddr = iph->daddr; | |
364 | qp->user = user; | |
365 | qp->len = 0; | |
366 | qp->meat = 0; | |
367 | qp->fragments = NULL; | |
368 | qp->iif = 0; | |
89cee8b1 | 369 | qp->peer = sysctl_ipfrag_max_dist ? inet_getpeer(iph->saddr, 1) : NULL; |
1da177e4 LT |
370 | |
371 | /* Initialize a timer for this entry. */ | |
372 | init_timer(&qp->timer); | |
373 | qp->timer.data = (unsigned long) qp; /* pointer to queue */ | |
374 | qp->timer.function = ip_expire; /* expire function */ | |
375 | spin_lock_init(&qp->lock); | |
376 | atomic_set(&qp->refcnt, 1); | |
377 | ||
55c0022e | 378 | return ip_frag_intern(qp); |
1da177e4 LT |
379 | |
380 | out_nomem: | |
64ce2073 | 381 | LIMIT_NETDEBUG(KERN_ERR "ip_frag_create: no memory left !\n"); |
1da177e4 LT |
382 | return NULL; |
383 | } | |
384 | ||
385 | /* Find the correct entry in the "incomplete datagrams" queue for | |
386 | * this IP datagram, and create new one, if nothing is found. | |
387 | */ | |
388 | static inline struct ipq *ip_find(struct iphdr *iph, u32 user) | |
389 | { | |
76ab608d | 390 | __be16 id = iph->id; |
18277770 AV |
391 | __be32 saddr = iph->saddr; |
392 | __be32 daddr = iph->daddr; | |
1da177e4 | 393 | __u8 protocol = iph->protocol; |
55c0022e | 394 | unsigned int hash; |
1da177e4 | 395 | struct ipq *qp; |
e7c8a41e | 396 | struct hlist_node *n; |
1da177e4 LT |
397 | |
398 | read_lock(&ipfrag_lock); | |
55c0022e | 399 | hash = ipqhashfn(id, saddr, daddr, protocol); |
e7c8a41e | 400 | hlist_for_each_entry(qp, n, &ipq_hash[hash], list) { |
1da177e4 LT |
401 | if(qp->id == id && |
402 | qp->saddr == saddr && | |
403 | qp->daddr == daddr && | |
404 | qp->protocol == protocol && | |
405 | qp->user == user) { | |
406 | atomic_inc(&qp->refcnt); | |
407 | read_unlock(&ipfrag_lock); | |
408 | return qp; | |
409 | } | |
410 | } | |
411 | read_unlock(&ipfrag_lock); | |
412 | ||
55c0022e | 413 | return ip_frag_create(iph, user); |
1da177e4 LT |
414 | } |
415 | ||
89cee8b1 HX |
416 | /* Is the fragment too far ahead to be part of ipq? */ |
417 | static inline int ip_frag_too_far(struct ipq *qp) | |
418 | { | |
419 | struct inet_peer *peer = qp->peer; | |
420 | unsigned int max = sysctl_ipfrag_max_dist; | |
421 | unsigned int start, end; | |
422 | ||
423 | int rc; | |
424 | ||
425 | if (!peer || !max) | |
426 | return 0; | |
427 | ||
428 | start = qp->rid; | |
429 | end = atomic_inc_return(&peer->rid); | |
430 | qp->rid = end; | |
431 | ||
432 | rc = qp->fragments && (end - start) > max; | |
433 | ||
434 | if (rc) { | |
435 | IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); | |
436 | } | |
437 | ||
438 | return rc; | |
439 | } | |
440 | ||
441 | static int ip_frag_reinit(struct ipq *qp) | |
442 | { | |
443 | struct sk_buff *fp; | |
444 | ||
445 | if (!mod_timer(&qp->timer, jiffies + sysctl_ipfrag_time)) { | |
446 | atomic_inc(&qp->refcnt); | |
447 | return -ETIMEDOUT; | |
448 | } | |
449 | ||
450 | fp = qp->fragments; | |
451 | do { | |
452 | struct sk_buff *xp = fp->next; | |
453 | frag_kfree_skb(fp, NULL); | |
454 | fp = xp; | |
455 | } while (fp); | |
456 | ||
457 | qp->last_in = 0; | |
458 | qp->len = 0; | |
459 | qp->meat = 0; | |
460 | qp->fragments = NULL; | |
461 | qp->iif = 0; | |
462 | ||
463 | return 0; | |
464 | } | |
465 | ||
1da177e4 LT |
466 | /* Add new segment to existing queue. */ |
467 | static void ip_frag_queue(struct ipq *qp, struct sk_buff *skb) | |
468 | { | |
469 | struct sk_buff *prev, *next; | |
470 | int flags, offset; | |
471 | int ihl, end; | |
472 | ||
473 | if (qp->last_in & COMPLETE) | |
474 | goto err; | |
475 | ||
89cee8b1 HX |
476 | if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) && |
477 | unlikely(ip_frag_too_far(qp)) && unlikely(ip_frag_reinit(qp))) { | |
478 | ipq_kill(qp); | |
479 | goto err; | |
480 | } | |
481 | ||
e905a9ed | 482 | offset = ntohs(skb->nh.iph->frag_off); |
1da177e4 LT |
483 | flags = offset & ~IP_OFFSET; |
484 | offset &= IP_OFFSET; | |
485 | offset <<= 3; /* offset is in 8-byte chunks */ | |
e905a9ed | 486 | ihl = skb->nh.iph->ihl * 4; |
1da177e4 LT |
487 | |
488 | /* Determine the position of this fragment. */ | |
e905a9ed | 489 | end = offset + skb->len - ihl; |
1da177e4 LT |
490 | |
491 | /* Is this the final fragment? */ | |
492 | if ((flags & IP_MF) == 0) { | |
493 | /* If we already have some bits beyond end | |
494 | * or have different end, the segment is corrrupted. | |
495 | */ | |
496 | if (end < qp->len || | |
497 | ((qp->last_in & LAST_IN) && end != qp->len)) | |
498 | goto err; | |
499 | qp->last_in |= LAST_IN; | |
500 | qp->len = end; | |
501 | } else { | |
502 | if (end&7) { | |
503 | end &= ~7; | |
504 | if (skb->ip_summed != CHECKSUM_UNNECESSARY) | |
505 | skb->ip_summed = CHECKSUM_NONE; | |
506 | } | |
507 | if (end > qp->len) { | |
508 | /* Some bits beyond end -> corruption. */ | |
509 | if (qp->last_in & LAST_IN) | |
510 | goto err; | |
511 | qp->len = end; | |
512 | } | |
513 | } | |
514 | if (end == offset) | |
515 | goto err; | |
516 | ||
517 | if (pskb_pull(skb, ihl) == NULL) | |
518 | goto err; | |
48bc41a4 | 519 | if (pskb_trim_rcsum(skb, end-offset)) |
1da177e4 LT |
520 | goto err; |
521 | ||
522 | /* Find out which fragments are in front and at the back of us | |
523 | * in the chain of fragments so far. We must know where to put | |
524 | * this fragment, right? | |
525 | */ | |
526 | prev = NULL; | |
527 | for(next = qp->fragments; next != NULL; next = next->next) { | |
528 | if (FRAG_CB(next)->offset >= offset) | |
529 | break; /* bingo! */ | |
530 | prev = next; | |
531 | } | |
532 | ||
533 | /* We found where to put this one. Check for overlap with | |
534 | * preceding fragment, and, if needed, align things so that | |
535 | * any overlaps are eliminated. | |
536 | */ | |
537 | if (prev) { | |
538 | int i = (FRAG_CB(prev)->offset + prev->len) - offset; | |
539 | ||
540 | if (i > 0) { | |
541 | offset += i; | |
542 | if (end <= offset) | |
543 | goto err; | |
544 | if (!pskb_pull(skb, i)) | |
545 | goto err; | |
546 | if (skb->ip_summed != CHECKSUM_UNNECESSARY) | |
547 | skb->ip_summed = CHECKSUM_NONE; | |
548 | } | |
549 | } | |
550 | ||
551 | while (next && FRAG_CB(next)->offset < end) { | |
552 | int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */ | |
553 | ||
554 | if (i < next->len) { | |
555 | /* Eat head of the next overlapped fragment | |
556 | * and leave the loop. The next ones cannot overlap. | |
557 | */ | |
558 | if (!pskb_pull(next, i)) | |
559 | goto err; | |
560 | FRAG_CB(next)->offset += i; | |
561 | qp->meat -= i; | |
562 | if (next->ip_summed != CHECKSUM_UNNECESSARY) | |
563 | next->ip_summed = CHECKSUM_NONE; | |
564 | break; | |
565 | } else { | |
566 | struct sk_buff *free_it = next; | |
567 | ||
47c6bf77 | 568 | /* Old fragment is completely overridden with |
1da177e4 LT |
569 | * new one drop it. |
570 | */ | |
571 | next = next->next; | |
572 | ||
573 | if (prev) | |
574 | prev->next = next; | |
575 | else | |
576 | qp->fragments = next; | |
577 | ||
578 | qp->meat -= free_it->len; | |
579 | frag_kfree_skb(free_it, NULL); | |
580 | } | |
581 | } | |
582 | ||
583 | FRAG_CB(skb)->offset = offset; | |
584 | ||
585 | /* Insert this fragment in the chain of fragments. */ | |
586 | skb->next = next; | |
587 | if (prev) | |
588 | prev->next = skb; | |
589 | else | |
590 | qp->fragments = skb; | |
591 | ||
e905a9ed YH |
592 | if (skb->dev) |
593 | qp->iif = skb->dev->ifindex; | |
1da177e4 | 594 | skb->dev = NULL; |
a61bbcf2 | 595 | skb_get_timestamp(skb, &qp->stamp); |
1da177e4 LT |
596 | qp->meat += skb->len; |
597 | atomic_add(skb->truesize, &ip_frag_mem); | |
598 | if (offset == 0) | |
599 | qp->last_in |= FIRST_IN; | |
600 | ||
601 | write_lock(&ipfrag_lock); | |
602 | list_move_tail(&qp->lru_list, &ipq_lru_list); | |
603 | write_unlock(&ipfrag_lock); | |
604 | ||
605 | return; | |
606 | ||
607 | err: | |
608 | kfree_skb(skb); | |
609 | } | |
610 | ||
611 | ||
612 | /* Build a new IP datagram from all its fragments. */ | |
613 | ||
614 | static struct sk_buff *ip_frag_reasm(struct ipq *qp, struct net_device *dev) | |
615 | { | |
616 | struct iphdr *iph; | |
617 | struct sk_buff *fp, *head = qp->fragments; | |
618 | int len; | |
619 | int ihlen; | |
620 | ||
621 | ipq_kill(qp); | |
622 | ||
623 | BUG_TRAP(head != NULL); | |
624 | BUG_TRAP(FRAG_CB(head)->offset == 0); | |
625 | ||
626 | /* Allocate a new buffer for the datagram. */ | |
627 | ihlen = head->nh.iph->ihl*4; | |
628 | len = ihlen + qp->len; | |
629 | ||
630 | if(len > 65535) | |
631 | goto out_oversize; | |
632 | ||
633 | /* Head of list must not be cloned. */ | |
634 | if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) | |
635 | goto out_nomem; | |
636 | ||
637 | /* If the first fragment is fragmented itself, we split | |
638 | * it to two chunks: the first with data and paged part | |
639 | * and the second, holding only fragments. */ | |
640 | if (skb_shinfo(head)->frag_list) { | |
641 | struct sk_buff *clone; | |
642 | int i, plen = 0; | |
643 | ||
644 | if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) | |
645 | goto out_nomem; | |
646 | clone->next = head->next; | |
647 | head->next = clone; | |
648 | skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; | |
649 | skb_shinfo(head)->frag_list = NULL; | |
650 | for (i=0; i<skb_shinfo(head)->nr_frags; i++) | |
651 | plen += skb_shinfo(head)->frags[i].size; | |
652 | clone->len = clone->data_len = head->data_len - plen; | |
653 | head->data_len -= clone->len; | |
654 | head->len -= clone->len; | |
655 | clone->csum = 0; | |
656 | clone->ip_summed = head->ip_summed; | |
657 | atomic_add(clone->truesize, &ip_frag_mem); | |
658 | } | |
659 | ||
660 | skb_shinfo(head)->frag_list = head->next; | |
661 | skb_push(head, head->data - head->nh.raw); | |
662 | atomic_sub(head->truesize, &ip_frag_mem); | |
663 | ||
664 | for (fp=head->next; fp; fp = fp->next) { | |
665 | head->data_len += fp->len; | |
666 | head->len += fp->len; | |
667 | if (head->ip_summed != fp->ip_summed) | |
668 | head->ip_summed = CHECKSUM_NONE; | |
84fa7933 | 669 | else if (head->ip_summed == CHECKSUM_COMPLETE) |
1da177e4 LT |
670 | head->csum = csum_add(head->csum, fp->csum); |
671 | head->truesize += fp->truesize; | |
672 | atomic_sub(fp->truesize, &ip_frag_mem); | |
673 | } | |
674 | ||
675 | head->next = NULL; | |
676 | head->dev = dev; | |
a61bbcf2 | 677 | skb_set_timestamp(head, &qp->stamp); |
1da177e4 LT |
678 | |
679 | iph = head->nh.iph; | |
680 | iph->frag_off = 0; | |
681 | iph->tot_len = htons(len); | |
682 | IP_INC_STATS_BH(IPSTATS_MIB_REASMOKS); | |
683 | qp->fragments = NULL; | |
684 | return head; | |
685 | ||
686 | out_nomem: | |
e905a9ed | 687 | LIMIT_NETDEBUG(KERN_ERR "IP: queue_glue: no memory for gluing " |
64ce2073 | 688 | "queue %p\n", qp); |
1da177e4 LT |
689 | goto out_fail; |
690 | out_oversize: | |
691 | if (net_ratelimit()) | |
692 | printk(KERN_INFO | |
693 | "Oversized IP packet from %d.%d.%d.%d.\n", | |
694 | NIPQUAD(qp->saddr)); | |
695 | out_fail: | |
696 | IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); | |
697 | return NULL; | |
698 | } | |
699 | ||
700 | /* Process an incoming IP datagram fragment. */ | |
701 | struct sk_buff *ip_defrag(struct sk_buff *skb, u32 user) | |
702 | { | |
703 | struct iphdr *iph = skb->nh.iph; | |
704 | struct ipq *qp; | |
705 | struct net_device *dev; | |
e905a9ed | 706 | |
1da177e4 LT |
707 | IP_INC_STATS_BH(IPSTATS_MIB_REASMREQDS); |
708 | ||
709 | /* Start by cleaning up the memory. */ | |
710 | if (atomic_read(&ip_frag_mem) > sysctl_ipfrag_high_thresh) | |
711 | ip_evictor(); | |
712 | ||
713 | dev = skb->dev; | |
714 | ||
715 | /* Lookup (or create) queue header */ | |
716 | if ((qp = ip_find(iph, user)) != NULL) { | |
717 | struct sk_buff *ret = NULL; | |
718 | ||
719 | spin_lock(&qp->lock); | |
720 | ||
721 | ip_frag_queue(qp, skb); | |
722 | ||
723 | if (qp->last_in == (FIRST_IN|LAST_IN) && | |
724 | qp->meat == qp->len) | |
725 | ret = ip_frag_reasm(qp, dev); | |
726 | ||
727 | spin_unlock(&qp->lock); | |
728 | ipq_put(qp, NULL); | |
729 | return ret; | |
730 | } | |
731 | ||
732 | IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); | |
733 | kfree_skb(skb); | |
734 | return NULL; | |
735 | } | |
736 | ||
737 | void ipfrag_init(void) | |
738 | { | |
739 | ipfrag_hash_rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^ | |
740 | (jiffies ^ (jiffies >> 6))); | |
741 | ||
742 | init_timer(&ipfrag_secret_timer); | |
743 | ipfrag_secret_timer.function = ipfrag_secret_rebuild; | |
744 | ipfrag_secret_timer.expires = jiffies + sysctl_ipfrag_secret_interval; | |
745 | add_timer(&ipfrag_secret_timer); | |
746 | } | |
747 | ||
748 | EXPORT_SYMBOL(ip_defrag); |