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Commit | Line | Data |
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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. | |
7 | * | |
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 | */ | |
57 | int sysctl_ipfrag_high_thresh = 256*1024; | |
58 | int sysctl_ipfrag_low_thresh = 192*1024; | |
59 | ||
89cee8b1 HX |
60 | int sysctl_ipfrag_max_dist = 64; |
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 | */ | |
65 | int sysctl_ipfrag_time = IP_FRAG_TIME; | |
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; | |
80 | u32 saddr; | |
81 | u32 daddr; | |
82 | u16 id; | |
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 | ||
126 | static unsigned int ipqhashfn(u16 id, u32 saddr, u32 daddr, u8 prot) | |
127 | { | |
128 | return jhash_3words((u32)id << 16 | prot, saddr, daddr, | |
129 | ipfrag_hash_rnd) & (IPQ_HASHSZ - 1); | |
130 | } | |
131 | ||
132 | static struct timer_list ipfrag_secret_timer; | |
133 | int sysctl_ipfrag_secret_interval = 10 * 60 * HZ; | |
134 | ||
135 | static void ipfrag_secret_rebuild(unsigned long dummy) | |
136 | { | |
137 | unsigned long now = jiffies; | |
138 | int i; | |
139 | ||
140 | write_lock(&ipfrag_lock); | |
141 | get_random_bytes(&ipfrag_hash_rnd, sizeof(u32)); | |
142 | for (i = 0; i < IPQ_HASHSZ; i++) { | |
143 | struct ipq *q; | |
e7c8a41e | 144 | struct hlist_node *p, *n; |
1da177e4 | 145 | |
e7c8a41e | 146 | hlist_for_each_entry_safe(q, p, n, &ipq_hash[i], list) { |
1da177e4 LT |
147 | unsigned int hval = ipqhashfn(q->id, q->saddr, |
148 | q->daddr, q->protocol); | |
149 | ||
150 | if (hval != i) { | |
e7c8a41e | 151 | hlist_del(&q->list); |
1da177e4 LT |
152 | |
153 | /* Relink to new hash chain. */ | |
e7c8a41e | 154 | hlist_add_head(&q->list, &ipq_hash[hval]); |
1da177e4 | 155 | } |
1da177e4 LT |
156 | } |
157 | } | |
158 | write_unlock(&ipfrag_lock); | |
159 | ||
160 | mod_timer(&ipfrag_secret_timer, now + sysctl_ipfrag_secret_interval); | |
161 | } | |
162 | ||
163 | atomic_t ip_frag_mem = ATOMIC_INIT(0); /* Memory used for fragments */ | |
164 | ||
165 | /* Memory Tracking Functions. */ | |
166 | static __inline__ void frag_kfree_skb(struct sk_buff *skb, int *work) | |
167 | { | |
168 | if (work) | |
169 | *work -= skb->truesize; | |
170 | atomic_sub(skb->truesize, &ip_frag_mem); | |
171 | kfree_skb(skb); | |
172 | } | |
173 | ||
174 | static __inline__ void frag_free_queue(struct ipq *qp, int *work) | |
175 | { | |
176 | if (work) | |
177 | *work -= sizeof(struct ipq); | |
178 | atomic_sub(sizeof(struct ipq), &ip_frag_mem); | |
179 | kfree(qp); | |
180 | } | |
181 | ||
182 | static __inline__ struct ipq *frag_alloc_queue(void) | |
183 | { | |
184 | struct ipq *qp = kmalloc(sizeof(struct ipq), GFP_ATOMIC); | |
185 | ||
186 | if(!qp) | |
187 | return NULL; | |
188 | atomic_add(sizeof(struct ipq), &ip_frag_mem); | |
189 | return qp; | |
190 | } | |
191 | ||
192 | ||
193 | /* Destruction primitives. */ | |
194 | ||
195 | /* Complete destruction of ipq. */ | |
196 | static void ip_frag_destroy(struct ipq *qp, int *work) | |
197 | { | |
198 | struct sk_buff *fp; | |
199 | ||
200 | BUG_TRAP(qp->last_in&COMPLETE); | |
201 | BUG_TRAP(del_timer(&qp->timer) == 0); | |
202 | ||
89cee8b1 HX |
203 | if (qp->peer) |
204 | inet_putpeer(qp->peer); | |
205 | ||
1da177e4 LT |
206 | /* Release all fragment data. */ |
207 | fp = qp->fragments; | |
208 | while (fp) { | |
209 | struct sk_buff *xp = fp->next; | |
210 | ||
211 | frag_kfree_skb(fp, work); | |
212 | fp = xp; | |
213 | } | |
214 | ||
215 | /* Finally, release the queue descriptor itself. */ | |
216 | frag_free_queue(qp, work); | |
217 | } | |
218 | ||
219 | static __inline__ void ipq_put(struct ipq *ipq, int *work) | |
220 | { | |
221 | if (atomic_dec_and_test(&ipq->refcnt)) | |
222 | ip_frag_destroy(ipq, work); | |
223 | } | |
224 | ||
225 | /* Kill ipq entry. It is not destroyed immediately, | |
226 | * because caller (and someone more) holds reference count. | |
227 | */ | |
228 | static void ipq_kill(struct ipq *ipq) | |
229 | { | |
230 | if (del_timer(&ipq->timer)) | |
231 | atomic_dec(&ipq->refcnt); | |
232 | ||
233 | if (!(ipq->last_in & COMPLETE)) { | |
234 | ipq_unlink(ipq); | |
235 | atomic_dec(&ipq->refcnt); | |
236 | ipq->last_in |= COMPLETE; | |
237 | } | |
238 | } | |
239 | ||
240 | /* Memory limiting on fragments. Evictor trashes the oldest | |
241 | * fragment queue until we are back under the threshold. | |
242 | */ | |
243 | static void ip_evictor(void) | |
244 | { | |
245 | struct ipq *qp; | |
246 | struct list_head *tmp; | |
247 | int work; | |
248 | ||
249 | work = atomic_read(&ip_frag_mem) - sysctl_ipfrag_low_thresh; | |
250 | if (work <= 0) | |
251 | return; | |
252 | ||
253 | while (work > 0) { | |
254 | read_lock(&ipfrag_lock); | |
255 | if (list_empty(&ipq_lru_list)) { | |
256 | read_unlock(&ipfrag_lock); | |
257 | return; | |
258 | } | |
259 | tmp = ipq_lru_list.next; | |
260 | qp = list_entry(tmp, struct ipq, lru_list); | |
261 | atomic_inc(&qp->refcnt); | |
262 | read_unlock(&ipfrag_lock); | |
263 | ||
264 | spin_lock(&qp->lock); | |
265 | if (!(qp->last_in&COMPLETE)) | |
266 | ipq_kill(qp); | |
267 | spin_unlock(&qp->lock); | |
268 | ||
269 | ipq_put(qp, &work); | |
270 | IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); | |
271 | } | |
272 | } | |
273 | ||
274 | /* | |
275 | * Oops, a fragment queue timed out. Kill it and send an ICMP reply. | |
276 | */ | |
277 | static void ip_expire(unsigned long arg) | |
278 | { | |
279 | struct ipq *qp = (struct ipq *) arg; | |
280 | ||
281 | spin_lock(&qp->lock); | |
282 | ||
283 | if (qp->last_in & COMPLETE) | |
284 | goto out; | |
285 | ||
286 | ipq_kill(qp); | |
287 | ||
288 | IP_INC_STATS_BH(IPSTATS_MIB_REASMTIMEOUT); | |
289 | IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); | |
290 | ||
291 | if ((qp->last_in&FIRST_IN) && qp->fragments != NULL) { | |
292 | struct sk_buff *head = qp->fragments; | |
293 | /* Send an ICMP "Fragment Reassembly Timeout" message. */ | |
294 | if ((head->dev = dev_get_by_index(qp->iif)) != NULL) { | |
295 | icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0); | |
296 | dev_put(head->dev); | |
297 | } | |
298 | } | |
299 | out: | |
300 | spin_unlock(&qp->lock); | |
301 | ipq_put(qp, NULL); | |
302 | } | |
303 | ||
304 | /* Creation primitives. */ | |
305 | ||
55c0022e | 306 | static struct ipq *ip_frag_intern(struct ipq *qp_in) |
1da177e4 LT |
307 | { |
308 | struct ipq *qp; | |
e7c8a41e YK |
309 | #ifdef CONFIG_SMP |
310 | struct hlist_node *n; | |
311 | #endif | |
55c0022e DM |
312 | unsigned int hash; |
313 | ||
1da177e4 | 314 | write_lock(&ipfrag_lock); |
55c0022e DM |
315 | hash = ipqhashfn(qp_in->id, qp_in->saddr, qp_in->daddr, |
316 | qp_in->protocol); | |
1da177e4 LT |
317 | #ifdef CONFIG_SMP |
318 | /* With SMP race we have to recheck hash table, because | |
319 | * such entry could be created on other cpu, while we | |
320 | * promoted read lock to write lock. | |
321 | */ | |
e7c8a41e | 322 | hlist_for_each_entry(qp, n, &ipq_hash[hash], list) { |
1da177e4 LT |
323 | if(qp->id == qp_in->id && |
324 | qp->saddr == qp_in->saddr && | |
325 | qp->daddr == qp_in->daddr && | |
326 | qp->protocol == qp_in->protocol && | |
327 | qp->user == qp_in->user) { | |
328 | atomic_inc(&qp->refcnt); | |
329 | write_unlock(&ipfrag_lock); | |
330 | qp_in->last_in |= COMPLETE; | |
331 | ipq_put(qp_in, NULL); | |
332 | return qp; | |
333 | } | |
334 | } | |
335 | #endif | |
336 | qp = qp_in; | |
337 | ||
338 | if (!mod_timer(&qp->timer, jiffies + sysctl_ipfrag_time)) | |
339 | atomic_inc(&qp->refcnt); | |
340 | ||
341 | atomic_inc(&qp->refcnt); | |
e7c8a41e | 342 | hlist_add_head(&qp->list, &ipq_hash[hash]); |
1da177e4 LT |
343 | INIT_LIST_HEAD(&qp->lru_list); |
344 | list_add_tail(&qp->lru_list, &ipq_lru_list); | |
345 | ip_frag_nqueues++; | |
346 | write_unlock(&ipfrag_lock); | |
347 | return qp; | |
348 | } | |
349 | ||
350 | /* Add an entry to the 'ipq' queue for a newly received IP datagram. */ | |
55c0022e | 351 | static struct ipq *ip_frag_create(struct iphdr *iph, u32 user) |
1da177e4 LT |
352 | { |
353 | struct ipq *qp; | |
354 | ||
355 | if ((qp = frag_alloc_queue()) == NULL) | |
356 | goto out_nomem; | |
357 | ||
358 | qp->protocol = iph->protocol; | |
359 | qp->last_in = 0; | |
360 | qp->id = iph->id; | |
361 | qp->saddr = iph->saddr; | |
362 | qp->daddr = iph->daddr; | |
363 | qp->user = user; | |
364 | qp->len = 0; | |
365 | qp->meat = 0; | |
366 | qp->fragments = NULL; | |
367 | qp->iif = 0; | |
89cee8b1 | 368 | qp->peer = sysctl_ipfrag_max_dist ? inet_getpeer(iph->saddr, 1) : NULL; |
1da177e4 LT |
369 | |
370 | /* Initialize a timer for this entry. */ | |
371 | init_timer(&qp->timer); | |
372 | qp->timer.data = (unsigned long) qp; /* pointer to queue */ | |
373 | qp->timer.function = ip_expire; /* expire function */ | |
374 | spin_lock_init(&qp->lock); | |
375 | atomic_set(&qp->refcnt, 1); | |
376 | ||
55c0022e | 377 | return ip_frag_intern(qp); |
1da177e4 LT |
378 | |
379 | out_nomem: | |
64ce2073 | 380 | LIMIT_NETDEBUG(KERN_ERR "ip_frag_create: no memory left !\n"); |
1da177e4 LT |
381 | return NULL; |
382 | } | |
383 | ||
384 | /* Find the correct entry in the "incomplete datagrams" queue for | |
385 | * this IP datagram, and create new one, if nothing is found. | |
386 | */ | |
387 | static inline struct ipq *ip_find(struct iphdr *iph, u32 user) | |
388 | { | |
76ab608d | 389 | __be16 id = iph->id; |
1da177e4 LT |
390 | __u32 saddr = iph->saddr; |
391 | __u32 daddr = iph->daddr; | |
392 | __u8 protocol = iph->protocol; | |
55c0022e | 393 | unsigned int hash; |
1da177e4 | 394 | struct ipq *qp; |
e7c8a41e | 395 | struct hlist_node *n; |
1da177e4 LT |
396 | |
397 | read_lock(&ipfrag_lock); | |
55c0022e | 398 | hash = ipqhashfn(id, saddr, daddr, protocol); |
e7c8a41e | 399 | hlist_for_each_entry(qp, n, &ipq_hash[hash], list) { |
1da177e4 LT |
400 | if(qp->id == id && |
401 | qp->saddr == saddr && | |
402 | qp->daddr == daddr && | |
403 | qp->protocol == protocol && | |
404 | qp->user == user) { | |
405 | atomic_inc(&qp->refcnt); | |
406 | read_unlock(&ipfrag_lock); | |
407 | return qp; | |
408 | } | |
409 | } | |
410 | read_unlock(&ipfrag_lock); | |
411 | ||
55c0022e | 412 | return ip_frag_create(iph, user); |
1da177e4 LT |
413 | } |
414 | ||
89cee8b1 HX |
415 | /* Is the fragment too far ahead to be part of ipq? */ |
416 | static inline int ip_frag_too_far(struct ipq *qp) | |
417 | { | |
418 | struct inet_peer *peer = qp->peer; | |
419 | unsigned int max = sysctl_ipfrag_max_dist; | |
420 | unsigned int start, end; | |
421 | ||
422 | int rc; | |
423 | ||
424 | if (!peer || !max) | |
425 | return 0; | |
426 | ||
427 | start = qp->rid; | |
428 | end = atomic_inc_return(&peer->rid); | |
429 | qp->rid = end; | |
430 | ||
431 | rc = qp->fragments && (end - start) > max; | |
432 | ||
433 | if (rc) { | |
434 | IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); | |
435 | } | |
436 | ||
437 | return rc; | |
438 | } | |
439 | ||
440 | static int ip_frag_reinit(struct ipq *qp) | |
441 | { | |
442 | struct sk_buff *fp; | |
443 | ||
444 | if (!mod_timer(&qp->timer, jiffies + sysctl_ipfrag_time)) { | |
445 | atomic_inc(&qp->refcnt); | |
446 | return -ETIMEDOUT; | |
447 | } | |
448 | ||
449 | fp = qp->fragments; | |
450 | do { | |
451 | struct sk_buff *xp = fp->next; | |
452 | frag_kfree_skb(fp, NULL); | |
453 | fp = xp; | |
454 | } while (fp); | |
455 | ||
456 | qp->last_in = 0; | |
457 | qp->len = 0; | |
458 | qp->meat = 0; | |
459 | qp->fragments = NULL; | |
460 | qp->iif = 0; | |
461 | ||
462 | return 0; | |
463 | } | |
464 | ||
1da177e4 LT |
465 | /* Add new segment to existing queue. */ |
466 | static void ip_frag_queue(struct ipq *qp, struct sk_buff *skb) | |
467 | { | |
468 | struct sk_buff *prev, *next; | |
469 | int flags, offset; | |
470 | int ihl, end; | |
471 | ||
472 | if (qp->last_in & COMPLETE) | |
473 | goto err; | |
474 | ||
89cee8b1 HX |
475 | if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) && |
476 | unlikely(ip_frag_too_far(qp)) && unlikely(ip_frag_reinit(qp))) { | |
477 | ipq_kill(qp); | |
478 | goto err; | |
479 | } | |
480 | ||
1da177e4 LT |
481 | offset = ntohs(skb->nh.iph->frag_off); |
482 | flags = offset & ~IP_OFFSET; | |
483 | offset &= IP_OFFSET; | |
484 | offset <<= 3; /* offset is in 8-byte chunks */ | |
485 | ihl = skb->nh.iph->ihl * 4; | |
486 | ||
487 | /* Determine the position of this fragment. */ | |
488 | end = offset + skb->len - ihl; | |
489 | ||
490 | /* Is this the final fragment? */ | |
491 | if ((flags & IP_MF) == 0) { | |
492 | /* If we already have some bits beyond end | |
493 | * or have different end, the segment is corrrupted. | |
494 | */ | |
495 | if (end < qp->len || | |
496 | ((qp->last_in & LAST_IN) && end != qp->len)) | |
497 | goto err; | |
498 | qp->last_in |= LAST_IN; | |
499 | qp->len = end; | |
500 | } else { | |
501 | if (end&7) { | |
502 | end &= ~7; | |
503 | if (skb->ip_summed != CHECKSUM_UNNECESSARY) | |
504 | skb->ip_summed = CHECKSUM_NONE; | |
505 | } | |
506 | if (end > qp->len) { | |
507 | /* Some bits beyond end -> corruption. */ | |
508 | if (qp->last_in & LAST_IN) | |
509 | goto err; | |
510 | qp->len = end; | |
511 | } | |
512 | } | |
513 | if (end == offset) | |
514 | goto err; | |
515 | ||
516 | if (pskb_pull(skb, ihl) == NULL) | |
517 | goto err; | |
48bc41a4 | 518 | if (pskb_trim_rcsum(skb, end-offset)) |
1da177e4 LT |
519 | goto err; |
520 | ||
521 | /* Find out which fragments are in front and at the back of us | |
522 | * in the chain of fragments so far. We must know where to put | |
523 | * this fragment, right? | |
524 | */ | |
525 | prev = NULL; | |
526 | for(next = qp->fragments; next != NULL; next = next->next) { | |
527 | if (FRAG_CB(next)->offset >= offset) | |
528 | break; /* bingo! */ | |
529 | prev = next; | |
530 | } | |
531 | ||
532 | /* We found where to put this one. Check for overlap with | |
533 | * preceding fragment, and, if needed, align things so that | |
534 | * any overlaps are eliminated. | |
535 | */ | |
536 | if (prev) { | |
537 | int i = (FRAG_CB(prev)->offset + prev->len) - offset; | |
538 | ||
539 | if (i > 0) { | |
540 | offset += i; | |
541 | if (end <= offset) | |
542 | goto err; | |
543 | if (!pskb_pull(skb, i)) | |
544 | goto err; | |
545 | if (skb->ip_summed != CHECKSUM_UNNECESSARY) | |
546 | skb->ip_summed = CHECKSUM_NONE; | |
547 | } | |
548 | } | |
549 | ||
550 | while (next && FRAG_CB(next)->offset < end) { | |
551 | int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */ | |
552 | ||
553 | if (i < next->len) { | |
554 | /* Eat head of the next overlapped fragment | |
555 | * and leave the loop. The next ones cannot overlap. | |
556 | */ | |
557 | if (!pskb_pull(next, i)) | |
558 | goto err; | |
559 | FRAG_CB(next)->offset += i; | |
560 | qp->meat -= i; | |
561 | if (next->ip_summed != CHECKSUM_UNNECESSARY) | |
562 | next->ip_summed = CHECKSUM_NONE; | |
563 | break; | |
564 | } else { | |
565 | struct sk_buff *free_it = next; | |
566 | ||
567 | /* Old fragmnet is completely overridden with | |
568 | * new one drop it. | |
569 | */ | |
570 | next = next->next; | |
571 | ||
572 | if (prev) | |
573 | prev->next = next; | |
574 | else | |
575 | qp->fragments = next; | |
576 | ||
577 | qp->meat -= free_it->len; | |
578 | frag_kfree_skb(free_it, NULL); | |
579 | } | |
580 | } | |
581 | ||
582 | FRAG_CB(skb)->offset = offset; | |
583 | ||
584 | /* Insert this fragment in the chain of fragments. */ | |
585 | skb->next = next; | |
586 | if (prev) | |
587 | prev->next = skb; | |
588 | else | |
589 | qp->fragments = skb; | |
590 | ||
591 | if (skb->dev) | |
592 | qp->iif = skb->dev->ifindex; | |
593 | skb->dev = NULL; | |
a61bbcf2 | 594 | skb_get_timestamp(skb, &qp->stamp); |
1da177e4 LT |
595 | qp->meat += skb->len; |
596 | atomic_add(skb->truesize, &ip_frag_mem); | |
597 | if (offset == 0) | |
598 | qp->last_in |= FIRST_IN; | |
599 | ||
600 | write_lock(&ipfrag_lock); | |
601 | list_move_tail(&qp->lru_list, &ipq_lru_list); | |
602 | write_unlock(&ipfrag_lock); | |
603 | ||
604 | return; | |
605 | ||
606 | err: | |
607 | kfree_skb(skb); | |
608 | } | |
609 | ||
610 | ||
611 | /* Build a new IP datagram from all its fragments. */ | |
612 | ||
613 | static struct sk_buff *ip_frag_reasm(struct ipq *qp, struct net_device *dev) | |
614 | { | |
615 | struct iphdr *iph; | |
616 | struct sk_buff *fp, *head = qp->fragments; | |
617 | int len; | |
618 | int ihlen; | |
619 | ||
620 | ipq_kill(qp); | |
621 | ||
622 | BUG_TRAP(head != NULL); | |
623 | BUG_TRAP(FRAG_CB(head)->offset == 0); | |
624 | ||
625 | /* Allocate a new buffer for the datagram. */ | |
626 | ihlen = head->nh.iph->ihl*4; | |
627 | len = ihlen + qp->len; | |
628 | ||
629 | if(len > 65535) | |
630 | goto out_oversize; | |
631 | ||
632 | /* Head of list must not be cloned. */ | |
633 | if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) | |
634 | goto out_nomem; | |
635 | ||
636 | /* If the first fragment is fragmented itself, we split | |
637 | * it to two chunks: the first with data and paged part | |
638 | * and the second, holding only fragments. */ | |
639 | if (skb_shinfo(head)->frag_list) { | |
640 | struct sk_buff *clone; | |
641 | int i, plen = 0; | |
642 | ||
643 | if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) | |
644 | goto out_nomem; | |
645 | clone->next = head->next; | |
646 | head->next = clone; | |
647 | skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; | |
648 | skb_shinfo(head)->frag_list = NULL; | |
649 | for (i=0; i<skb_shinfo(head)->nr_frags; i++) | |
650 | plen += skb_shinfo(head)->frags[i].size; | |
651 | clone->len = clone->data_len = head->data_len - plen; | |
652 | head->data_len -= clone->len; | |
653 | head->len -= clone->len; | |
654 | clone->csum = 0; | |
655 | clone->ip_summed = head->ip_summed; | |
656 | atomic_add(clone->truesize, &ip_frag_mem); | |
657 | } | |
658 | ||
659 | skb_shinfo(head)->frag_list = head->next; | |
660 | skb_push(head, head->data - head->nh.raw); | |
661 | atomic_sub(head->truesize, &ip_frag_mem); | |
662 | ||
663 | for (fp=head->next; fp; fp = fp->next) { | |
664 | head->data_len += fp->len; | |
665 | head->len += fp->len; | |
666 | if (head->ip_summed != fp->ip_summed) | |
667 | head->ip_summed = CHECKSUM_NONE; | |
668 | else if (head->ip_summed == CHECKSUM_HW) | |
669 | head->csum = csum_add(head->csum, fp->csum); | |
670 | head->truesize += fp->truesize; | |
671 | atomic_sub(fp->truesize, &ip_frag_mem); | |
672 | } | |
673 | ||
674 | head->next = NULL; | |
675 | head->dev = dev; | |
a61bbcf2 | 676 | skb_set_timestamp(head, &qp->stamp); |
1da177e4 LT |
677 | |
678 | iph = head->nh.iph; | |
679 | iph->frag_off = 0; | |
680 | iph->tot_len = htons(len); | |
681 | IP_INC_STATS_BH(IPSTATS_MIB_REASMOKS); | |
682 | qp->fragments = NULL; | |
683 | return head; | |
684 | ||
685 | out_nomem: | |
64ce2073 PM |
686 | LIMIT_NETDEBUG(KERN_ERR "IP: queue_glue: no memory for gluing " |
687 | "queue %p\n", qp); | |
1da177e4 LT |
688 | goto out_fail; |
689 | out_oversize: | |
690 | if (net_ratelimit()) | |
691 | printk(KERN_INFO | |
692 | "Oversized IP packet from %d.%d.%d.%d.\n", | |
693 | NIPQUAD(qp->saddr)); | |
694 | out_fail: | |
695 | IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); | |
696 | return NULL; | |
697 | } | |
698 | ||
699 | /* Process an incoming IP datagram fragment. */ | |
700 | struct sk_buff *ip_defrag(struct sk_buff *skb, u32 user) | |
701 | { | |
702 | struct iphdr *iph = skb->nh.iph; | |
703 | struct ipq *qp; | |
704 | struct net_device *dev; | |
705 | ||
706 | IP_INC_STATS_BH(IPSTATS_MIB_REASMREQDS); | |
707 | ||
708 | /* Start by cleaning up the memory. */ | |
709 | if (atomic_read(&ip_frag_mem) > sysctl_ipfrag_high_thresh) | |
710 | ip_evictor(); | |
711 | ||
712 | dev = skb->dev; | |
713 | ||
714 | /* Lookup (or create) queue header */ | |
715 | if ((qp = ip_find(iph, user)) != NULL) { | |
716 | struct sk_buff *ret = NULL; | |
717 | ||
718 | spin_lock(&qp->lock); | |
719 | ||
720 | ip_frag_queue(qp, skb); | |
721 | ||
722 | if (qp->last_in == (FIRST_IN|LAST_IN) && | |
723 | qp->meat == qp->len) | |
724 | ret = ip_frag_reasm(qp, dev); | |
725 | ||
726 | spin_unlock(&qp->lock); | |
727 | ipq_put(qp, NULL); | |
728 | return ret; | |
729 | } | |
730 | ||
731 | IP_INC_STATS_BH(IPSTATS_MIB_REASMFAILS); | |
732 | kfree_skb(skb); | |
733 | return NULL; | |
734 | } | |
735 | ||
736 | void ipfrag_init(void) | |
737 | { | |
738 | ipfrag_hash_rnd = (u32) ((num_physpages ^ (num_physpages>>7)) ^ | |
739 | (jiffies ^ (jiffies >> 6))); | |
740 | ||
741 | init_timer(&ipfrag_secret_timer); | |
742 | ipfrag_secret_timer.function = ipfrag_secret_rebuild; | |
743 | ipfrag_secret_timer.expires = jiffies + sysctl_ipfrag_secret_interval; | |
744 | add_timer(&ipfrag_secret_timer); | |
745 | } | |
746 | ||
747 | EXPORT_SYMBOL(ip_defrag); |