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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
2 | /* |
3 | * INET An implementation of the TCP/IP protocol suite for the LINUX | |
4 | * operating system. INET is implemented using the BSD Socket | |
5 | * interface as the means of communication with the user level. | |
6 | * | |
7 | * The IP fragmentation functionality. | |
e905a9ed | 8 | * |
1da177e4 | 9 | * Authors: Fred N. van Kempen <waltje@uWalt.NL.Mugnet.ORG> |
113aa838 | 10 | * Alan Cox <alan@lxorguk.ukuu.org.uk> |
1da177e4 LT |
11 | * |
12 | * Fixes: | |
13 | * Alan Cox : Split from ip.c , see ip_input.c for history. | |
14 | * David S. Miller : Begin massive cleanup... | |
15 | * Andi Kleen : Add sysctls. | |
16 | * xxxx : Overlapfrag bug. | |
17 | * Ultima : ip_expire() kernel panic. | |
18 | * Bill Hawes : Frag accounting and evictor fixes. | |
19 | * John McDonald : 0 length frag bug. | |
20 | * Alexey Kuznetsov: SMP races, threading, cleanup. | |
21 | * Patrick McHardy : LRU queue of frag heads for evictor. | |
22 | */ | |
23 | ||
afd46503 JP |
24 | #define pr_fmt(fmt) "IPv4: " fmt |
25 | ||
89cee8b1 | 26 | #include <linux/compiler.h> |
1da177e4 LT |
27 | #include <linux/module.h> |
28 | #include <linux/types.h> | |
29 | #include <linux/mm.h> | |
30 | #include <linux/jiffies.h> | |
31 | #include <linux/skbuff.h> | |
32 | #include <linux/list.h> | |
33 | #include <linux/ip.h> | |
34 | #include <linux/icmp.h> | |
35 | #include <linux/netdevice.h> | |
36 | #include <linux/jhash.h> | |
37 | #include <linux/random.h> | |
5a0e3ad6 | 38 | #include <linux/slab.h> |
e9017b55 SW |
39 | #include <net/route.h> |
40 | #include <net/dst.h> | |
1da177e4 LT |
41 | #include <net/sock.h> |
42 | #include <net/ip.h> | |
43 | #include <net/icmp.h> | |
44 | #include <net/checksum.h> | |
89cee8b1 | 45 | #include <net/inetpeer.h> |
5ab11c98 | 46 | #include <net/inet_frag.h> |
1da177e4 LT |
47 | #include <linux/tcp.h> |
48 | #include <linux/udp.h> | |
49 | #include <linux/inet.h> | |
50 | #include <linux/netfilter_ipv4.h> | |
6623e3b2 | 51 | #include <net/inet_ecn.h> |
385add90 | 52 | #include <net/l3mdev.h> |
1da177e4 LT |
53 | |
54 | /* NOTE. Logic of IP defragmentation is parallel to corresponding IPv6 | |
55 | * code now. If you change something here, _PLEASE_ update ipv6/reassembly.c | |
56 | * as well. Or notify me, at least. --ANK | |
57 | */ | |
d4ad4d22 | 58 | static const char ip_frag_cache_name[] = "ip4-frags"; |
89cee8b1 | 59 | |
1da177e4 LT |
60 | struct ipfrag_skb_cb |
61 | { | |
62 | struct inet_skb_parm h; | |
63 | int offset; | |
64 | }; | |
65 | ||
fd3f8c4c | 66 | #define FRAG_CB(skb) ((struct ipfrag_skb_cb *)((skb)->cb)) |
1da177e4 LT |
67 | |
68 | /* Describe an entry in the "incomplete datagrams" queue. */ | |
69 | struct ipq { | |
5ab11c98 PE |
70 | struct inet_frag_queue q; |
71 | ||
6623e3b2 | 72 | u8 ecn; /* RFC3168 support */ |
d6b915e2 | 73 | u16 max_df_size; /* largest frag with DF set seen */ |
89cee8b1 HX |
74 | int iif; |
75 | unsigned int rid; | |
76 | struct inet_peer *peer; | |
1da177e4 LT |
77 | }; |
78 | ||
aa1f731e | 79 | static u8 ip4_frag_ecn(u8 tos) |
6623e3b2 | 80 | { |
5173cc05 | 81 | return 1 << (tos & INET_ECN_MASK); |
6623e3b2 ED |
82 | } |
83 | ||
7eb95156 | 84 | static struct inet_frags ip4_frags; |
1da177e4 | 85 | |
1706d587 HX |
86 | static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, |
87 | struct net_device *dev); | |
88 | ||
abd6523d | 89 | |
36c77782 | 90 | static void ip4_frag_init(struct inet_frag_queue *q, const void *a) |
c6fda282 PE |
91 | { |
92 | struct ipq *qp = container_of(q, struct ipq, q); | |
54db0cc2 G |
93 | struct netns_ipv4 *ipv4 = container_of(q->net, struct netns_ipv4, |
94 | frags); | |
95 | struct net *net = container_of(ipv4, struct net, ipv4); | |
96 | ||
4e722036 | 97 | const struct frag_v4_compare_key *key = a; |
c6fda282 | 98 | |
4e722036 ED |
99 | q->key.v4 = *key; |
100 | qp->ecn = 0; | |
0fbf4cb2 | 101 | qp->peer = q->net->max_dist ? |
4e722036 | 102 | inet_getpeer_v4(net->ipv4.peers, key->saddr, key->vif, 1) : |
192132b9 | 103 | NULL; |
c6fda282 PE |
104 | } |
105 | ||
aa1f731e | 106 | static void ip4_frag_free(struct inet_frag_queue *q) |
1da177e4 | 107 | { |
1e4b8287 PE |
108 | struct ipq *qp; |
109 | ||
110 | qp = container_of(q, struct ipq, q); | |
111 | if (qp->peer) | |
112 | inet_putpeer(qp->peer); | |
1da177e4 LT |
113 | } |
114 | ||
1da177e4 LT |
115 | |
116 | /* Destruction primitives. */ | |
117 | ||
aa1f731e | 118 | static void ipq_put(struct ipq *ipq) |
1da177e4 | 119 | { |
9bdf9ca9 | 120 | inet_frag_put(&ipq->q); |
1da177e4 LT |
121 | } |
122 | ||
123 | /* Kill ipq entry. It is not destroyed immediately, | |
124 | * because caller (and someone more) holds reference count. | |
125 | */ | |
126 | static void ipq_kill(struct ipq *ipq) | |
127 | { | |
9bdf9ca9 | 128 | inet_frag_kill(&ipq->q); |
1da177e4 LT |
129 | } |
130 | ||
5cf42280 AZ |
131 | static bool frag_expire_skip_icmp(u32 user) |
132 | { | |
133 | return user == IP_DEFRAG_AF_PACKET || | |
134 | ip_defrag_user_in_between(user, IP_DEFRAG_CONNTRACK_IN, | |
8bc04864 AZ |
135 | __IP_DEFRAG_CONNTRACK_IN_END) || |
136 | ip_defrag_user_in_between(user, IP_DEFRAG_CONNTRACK_BRIDGE_IN, | |
137 | __IP_DEFRAG_CONNTRACK_BRIDGE_IN); | |
5cf42280 AZ |
138 | } |
139 | ||
1da177e4 LT |
140 | /* |
141 | * Oops, a fragment queue timed out. Kill it and send an ICMP reply. | |
142 | */ | |
78802011 | 143 | static void ip_expire(struct timer_list *t) |
1da177e4 | 144 | { |
78802011 | 145 | struct inet_frag_queue *frag = from_timer(frag, t, timer); |
ea41b4d2 ED |
146 | struct sk_buff *clone, *head; |
147 | const struct iphdr *iph; | |
84a3aa00 | 148 | struct net *net; |
ea41b4d2 ED |
149 | struct ipq *qp; |
150 | int err; | |
e521db9d | 151 | |
78802011 | 152 | qp = container_of(frag, struct ipq, q); |
84a3aa00 | 153 | net = container_of(qp->q.net, struct net, ipv4.frags); |
1da177e4 | 154 | |
ec4fbd64 | 155 | rcu_read_lock(); |
5ab11c98 | 156 | spin_lock(&qp->q.lock); |
1da177e4 | 157 | |
06aa8b8a | 158 | if (qp->q.flags & INET_FRAG_COMPLETE) |
1da177e4 LT |
159 | goto out; |
160 | ||
161 | ipq_kill(qp); | |
b45386ef | 162 | __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS); |
1da177e4 | 163 | |
ea41b4d2 | 164 | head = qp->q.fragments; |
cb84663e | 165 | |
ea41b4d2 | 166 | __IP_INC_STATS(net, IPSTATS_MIB_REASMTIMEOUT); |
2e404f63 | 167 | |
ea41b4d2 ED |
168 | if (!(qp->q.flags & INET_FRAG_FIRST_IN) || !head) |
169 | goto out; | |
2e404f63 | 170 | |
ea41b4d2 ED |
171 | head->dev = dev_get_by_index_rcu(net, qp->iif); |
172 | if (!head->dev) | |
173 | goto out; | |
ec4fbd64 | 174 | |
e9017b55 | 175 | |
ea41b4d2 ED |
176 | /* skb has no dst, perform route lookup again */ |
177 | iph = ip_hdr(head); | |
178 | err = ip_route_input_noref(head, iph->daddr, iph->saddr, | |
c6cffba4 | 179 | iph->tos, head->dev); |
ea41b4d2 ED |
180 | if (err) |
181 | goto out; | |
182 | ||
183 | /* Only an end host needs to send an ICMP | |
184 | * "Fragment Reassembly Timeout" message, per RFC792. | |
185 | */ | |
186 | if (frag_expire_skip_icmp(qp->q.key.v4.user) && | |
187 | (skb_rtable(head)->rt_type != RTN_LOCAL)) | |
188 | goto out; | |
189 | ||
190 | clone = skb_clone(head, GFP_ATOMIC); | |
191 | ||
192 | /* Send an ICMP "Fragment Reassembly Timeout" message. */ | |
193 | if (clone) { | |
194 | spin_unlock(&qp->q.lock); | |
195 | icmp_send(clone, ICMP_TIME_EXCEEDED, | |
196 | ICMP_EXC_FRAGTIME, 0); | |
197 | consume_skb(clone); | |
198 | goto out_rcu_unlock; | |
d1c9ae6d | 199 | } |
1da177e4 | 200 | out: |
5ab11c98 | 201 | spin_unlock(&qp->q.lock); |
ec4fbd64 ED |
202 | out_rcu_unlock: |
203 | rcu_read_unlock(); | |
4b6cb5d8 | 204 | ipq_put(qp); |
1da177e4 LT |
205 | } |
206 | ||
abd6523d PE |
207 | /* Find the correct entry in the "incomplete datagrams" queue for |
208 | * this IP datagram, and create new one, if nothing is found. | |
209 | */ | |
9972f134 DA |
210 | static struct ipq *ip_find(struct net *net, struct iphdr *iph, |
211 | u32 user, int vif) | |
1da177e4 | 212 | { |
4e722036 ED |
213 | struct frag_v4_compare_key key = { |
214 | .saddr = iph->saddr, | |
215 | .daddr = iph->daddr, | |
216 | .user = user, | |
217 | .vif = vif, | |
218 | .id = iph->id, | |
219 | .protocol = iph->protocol, | |
220 | }; | |
c6fda282 | 221 | struct inet_frag_queue *q; |
9a375803 | 222 | |
4e722036 | 223 | q = inet_frag_find(&net->ipv4.frags, &key); |
79583fc1 | 224 | if (!q) |
5a3da1fe | 225 | return NULL; |
79583fc1 | 226 | |
c6fda282 | 227 | return container_of(q, struct ipq, q); |
1da177e4 LT |
228 | } |
229 | ||
89cee8b1 | 230 | /* Is the fragment too far ahead to be part of ipq? */ |
aa1f731e | 231 | static int ip_frag_too_far(struct ipq *qp) |
89cee8b1 HX |
232 | { |
233 | struct inet_peer *peer = qp->peer; | |
0fbf4cb2 | 234 | unsigned int max = qp->q.net->max_dist; |
89cee8b1 HX |
235 | unsigned int start, end; |
236 | ||
237 | int rc; | |
238 | ||
239 | if (!peer || !max) | |
240 | return 0; | |
241 | ||
242 | start = qp->rid; | |
243 | end = atomic_inc_return(&peer->rid); | |
244 | qp->rid = end; | |
245 | ||
5ab11c98 | 246 | rc = qp->q.fragments && (end - start) > max; |
89cee8b1 HX |
247 | |
248 | if (rc) { | |
7c73a6fa PE |
249 | struct net *net; |
250 | ||
251 | net = container_of(qp->q.net, struct net, ipv4.frags); | |
b45386ef | 252 | __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS); |
89cee8b1 HX |
253 | } |
254 | ||
255 | return rc; | |
256 | } | |
257 | ||
258 | static int ip_frag_reinit(struct ipq *qp) | |
259 | { | |
260 | struct sk_buff *fp; | |
d433673e | 261 | unsigned int sum_truesize = 0; |
89cee8b1 | 262 | |
b2fd5321 | 263 | if (!mod_timer(&qp->q.timer, jiffies + qp->q.net->timeout)) { |
edcb6918 | 264 | refcount_inc(&qp->q.refcnt); |
89cee8b1 HX |
265 | return -ETIMEDOUT; |
266 | } | |
267 | ||
5ab11c98 | 268 | fp = qp->q.fragments; |
89cee8b1 HX |
269 | do { |
270 | struct sk_buff *xp = fp->next; | |
d433673e JDB |
271 | |
272 | sum_truesize += fp->truesize; | |
273 | kfree_skb(fp); | |
89cee8b1 HX |
274 | fp = xp; |
275 | } while (fp); | |
0e60d245 | 276 | sub_frag_mem_limit(qp->q.net, sum_truesize); |
89cee8b1 | 277 | |
06aa8b8a | 278 | qp->q.flags = 0; |
5ab11c98 PE |
279 | qp->q.len = 0; |
280 | qp->q.meat = 0; | |
281 | qp->q.fragments = NULL; | |
d6bebca9 | 282 | qp->q.fragments_tail = NULL; |
89cee8b1 | 283 | qp->iif = 0; |
6623e3b2 | 284 | qp->ecn = 0; |
89cee8b1 HX |
285 | |
286 | return 0; | |
287 | } | |
288 | ||
1da177e4 | 289 | /* Add new segment to existing queue. */ |
1706d587 | 290 | static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) |
1da177e4 LT |
291 | { |
292 | struct sk_buff *prev, *next; | |
1706d587 | 293 | struct net_device *dev; |
d6b915e2 | 294 | unsigned int fragsize; |
1da177e4 LT |
295 | int flags, offset; |
296 | int ihl, end; | |
1706d587 | 297 | int err = -ENOENT; |
6623e3b2 | 298 | u8 ecn; |
1da177e4 | 299 | |
06aa8b8a | 300 | if (qp->q.flags & INET_FRAG_COMPLETE) |
1da177e4 LT |
301 | goto err; |
302 | ||
89cee8b1 | 303 | if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) && |
1706d587 HX |
304 | unlikely(ip_frag_too_far(qp)) && |
305 | unlikely(err = ip_frag_reinit(qp))) { | |
89cee8b1 HX |
306 | ipq_kill(qp); |
307 | goto err; | |
308 | } | |
309 | ||
6623e3b2 | 310 | ecn = ip4_frag_ecn(ip_hdr(skb)->tos); |
eddc9ec5 | 311 | offset = ntohs(ip_hdr(skb)->frag_off); |
1da177e4 LT |
312 | flags = offset & ~IP_OFFSET; |
313 | offset &= IP_OFFSET; | |
314 | offset <<= 3; /* offset is in 8-byte chunks */ | |
c9bdd4b5 | 315 | ihl = ip_hdrlen(skb); |
1da177e4 LT |
316 | |
317 | /* Determine the position of this fragment. */ | |
0848f642 | 318 | end = offset + skb->len - skb_network_offset(skb) - ihl; |
1706d587 | 319 | err = -EINVAL; |
1da177e4 LT |
320 | |
321 | /* Is this the final fragment? */ | |
322 | if ((flags & IP_MF) == 0) { | |
323 | /* If we already have some bits beyond end | |
42b2aa86 | 324 | * or have different end, the segment is corrupted. |
1da177e4 | 325 | */ |
5ab11c98 | 326 | if (end < qp->q.len || |
06aa8b8a | 327 | ((qp->q.flags & INET_FRAG_LAST_IN) && end != qp->q.len)) |
1da177e4 | 328 | goto err; |
06aa8b8a | 329 | qp->q.flags |= INET_FRAG_LAST_IN; |
5ab11c98 | 330 | qp->q.len = end; |
1da177e4 LT |
331 | } else { |
332 | if (end&7) { | |
333 | end &= ~7; | |
334 | if (skb->ip_summed != CHECKSUM_UNNECESSARY) | |
335 | skb->ip_summed = CHECKSUM_NONE; | |
336 | } | |
5ab11c98 | 337 | if (end > qp->q.len) { |
1da177e4 | 338 | /* Some bits beyond end -> corruption. */ |
06aa8b8a | 339 | if (qp->q.flags & INET_FRAG_LAST_IN) |
1da177e4 | 340 | goto err; |
5ab11c98 | 341 | qp->q.len = end; |
1da177e4 LT |
342 | } |
343 | } | |
344 | if (end == offset) | |
345 | goto err; | |
346 | ||
1706d587 | 347 | err = -ENOMEM; |
0848f642 | 348 | if (!pskb_pull(skb, skb_network_offset(skb) + ihl)) |
1da177e4 | 349 | goto err; |
1706d587 HX |
350 | |
351 | err = pskb_trim_rcsum(skb, end - offset); | |
352 | if (err) | |
1da177e4 LT |
353 | goto err; |
354 | ||
355 | /* Find out which fragments are in front and at the back of us | |
356 | * in the chain of fragments so far. We must know where to put | |
357 | * this fragment, right? | |
358 | */ | |
d6bebca9 CG |
359 | prev = qp->q.fragments_tail; |
360 | if (!prev || FRAG_CB(prev)->offset < offset) { | |
361 | next = NULL; | |
362 | goto found; | |
363 | } | |
1da177e4 | 364 | prev = NULL; |
5ab11c98 | 365 | for (next = qp->q.fragments; next != NULL; next = next->next) { |
1da177e4 LT |
366 | if (FRAG_CB(next)->offset >= offset) |
367 | break; /* bingo! */ | |
368 | prev = next; | |
369 | } | |
370 | ||
d6bebca9 | 371 | found: |
1da177e4 LT |
372 | /* We found where to put this one. Check for overlap with |
373 | * preceding fragment, and, if needed, align things so that | |
374 | * any overlaps are eliminated. | |
375 | */ | |
376 | if (prev) { | |
377 | int i = (FRAG_CB(prev)->offset + prev->len) - offset; | |
378 | ||
379 | if (i > 0) { | |
380 | offset += i; | |
1706d587 | 381 | err = -EINVAL; |
1da177e4 LT |
382 | if (end <= offset) |
383 | goto err; | |
1706d587 | 384 | err = -ENOMEM; |
1da177e4 LT |
385 | if (!pskb_pull(skb, i)) |
386 | goto err; | |
387 | if (skb->ip_summed != CHECKSUM_UNNECESSARY) | |
388 | skb->ip_summed = CHECKSUM_NONE; | |
389 | } | |
390 | } | |
391 | ||
1706d587 HX |
392 | err = -ENOMEM; |
393 | ||
1da177e4 LT |
394 | while (next && FRAG_CB(next)->offset < end) { |
395 | int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */ | |
396 | ||
397 | if (i < next->len) { | |
148854d4 ED |
398 | int delta = -next->truesize; |
399 | ||
1da177e4 LT |
400 | /* Eat head of the next overlapped fragment |
401 | * and leave the loop. The next ones cannot overlap. | |
402 | */ | |
403 | if (!pskb_pull(next, i)) | |
404 | goto err; | |
148854d4 ED |
405 | delta += next->truesize; |
406 | if (delta) | |
407 | add_frag_mem_limit(qp->q.net, delta); | |
1da177e4 | 408 | FRAG_CB(next)->offset += i; |
5ab11c98 | 409 | qp->q.meat -= i; |
1da177e4 LT |
410 | if (next->ip_summed != CHECKSUM_UNNECESSARY) |
411 | next->ip_summed = CHECKSUM_NONE; | |
412 | break; | |
413 | } else { | |
414 | struct sk_buff *free_it = next; | |
415 | ||
47c6bf77 | 416 | /* Old fragment is completely overridden with |
1da177e4 LT |
417 | * new one drop it. |
418 | */ | |
419 | next = next->next; | |
420 | ||
421 | if (prev) | |
422 | prev->next = next; | |
423 | else | |
5ab11c98 | 424 | qp->q.fragments = next; |
1da177e4 | 425 | |
5ab11c98 | 426 | qp->q.meat -= free_it->len; |
0e60d245 | 427 | sub_frag_mem_limit(qp->q.net, free_it->truesize); |
d433673e | 428 | kfree_skb(free_it); |
1da177e4 LT |
429 | } |
430 | } | |
431 | ||
432 | FRAG_CB(skb)->offset = offset; | |
433 | ||
434 | /* Insert this fragment in the chain of fragments. */ | |
435 | skb->next = next; | |
d6bebca9 CG |
436 | if (!next) |
437 | qp->q.fragments_tail = skb; | |
1da177e4 LT |
438 | if (prev) |
439 | prev->next = skb; | |
440 | else | |
5ab11c98 | 441 | qp->q.fragments = skb; |
1da177e4 | 442 | |
1706d587 HX |
443 | dev = skb->dev; |
444 | if (dev) { | |
445 | qp->iif = dev->ifindex; | |
446 | skb->dev = NULL; | |
447 | } | |
5ab11c98 PE |
448 | qp->q.stamp = skb->tstamp; |
449 | qp->q.meat += skb->len; | |
6623e3b2 | 450 | qp->ecn |= ecn; |
0e60d245 | 451 | add_frag_mem_limit(qp->q.net, skb->truesize); |
1da177e4 | 452 | if (offset == 0) |
06aa8b8a | 453 | qp->q.flags |= INET_FRAG_FIRST_IN; |
1da177e4 | 454 | |
d6b915e2 FW |
455 | fragsize = skb->len + ihl; |
456 | ||
457 | if (fragsize > qp->q.max_size) | |
458 | qp->q.max_size = fragsize; | |
459 | ||
5f2d04f1 | 460 | if (ip_hdr(skb)->frag_off & htons(IP_DF) && |
d6b915e2 FW |
461 | fragsize > qp->max_df_size) |
462 | qp->max_df_size = fragsize; | |
5f2d04f1 | 463 | |
06aa8b8a | 464 | if (qp->q.flags == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && |
97599dc7 ED |
465 | qp->q.meat == qp->q.len) { |
466 | unsigned long orefdst = skb->_skb_refdst; | |
1706d587 | 467 | |
97599dc7 ED |
468 | skb->_skb_refdst = 0UL; |
469 | err = ip_frag_reasm(qp, prev, dev); | |
470 | skb->_skb_refdst = orefdst; | |
471 | return err; | |
472 | } | |
473 | ||
474 | skb_dst_drop(skb); | |
1706d587 | 475 | return -EINPROGRESS; |
1da177e4 LT |
476 | |
477 | err: | |
478 | kfree_skb(skb); | |
1706d587 | 479 | return err; |
1da177e4 LT |
480 | } |
481 | ||
482 | ||
483 | /* Build a new IP datagram from all its fragments. */ | |
484 | ||
1706d587 HX |
485 | static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, |
486 | struct net_device *dev) | |
1da177e4 | 487 | { |
2bad35b7 | 488 | struct net *net = container_of(qp->q.net, struct net, ipv4.frags); |
1da177e4 | 489 | struct iphdr *iph; |
5ab11c98 | 490 | struct sk_buff *fp, *head = qp->q.fragments; |
1da177e4 LT |
491 | int len; |
492 | int ihlen; | |
1706d587 | 493 | int err; |
5173cc05 | 494 | u8 ecn; |
1da177e4 LT |
495 | |
496 | ipq_kill(qp); | |
497 | ||
be991971 | 498 | ecn = ip_frag_ecn_table[qp->ecn]; |
5173cc05 ED |
499 | if (unlikely(ecn == 0xff)) { |
500 | err = -EINVAL; | |
501 | goto out_fail; | |
502 | } | |
1706d587 HX |
503 | /* Make the one we just received the head. */ |
504 | if (prev) { | |
505 | head = prev->next; | |
506 | fp = skb_clone(head, GFP_ATOMIC); | |
1706d587 HX |
507 | if (!fp) |
508 | goto out_nomem; | |
509 | ||
510 | fp->next = head->next; | |
d6bebca9 CG |
511 | if (!fp->next) |
512 | qp->q.fragments_tail = fp; | |
1706d587 HX |
513 | prev->next = fp; |
514 | ||
5ab11c98 PE |
515 | skb_morph(head, qp->q.fragments); |
516 | head->next = qp->q.fragments->next; | |
1706d587 | 517 | |
cbf8f7bb | 518 | consume_skb(qp->q.fragments); |
5ab11c98 | 519 | qp->q.fragments = head; |
1706d587 HX |
520 | } |
521 | ||
51456b29 | 522 | WARN_ON(!head); |
547b792c | 523 | WARN_ON(FRAG_CB(head)->offset != 0); |
1da177e4 LT |
524 | |
525 | /* Allocate a new buffer for the datagram. */ | |
c9bdd4b5 | 526 | ihlen = ip_hdrlen(head); |
5ab11c98 | 527 | len = ihlen + qp->q.len; |
1da177e4 | 528 | |
1706d587 | 529 | err = -E2BIG; |
132adf54 | 530 | if (len > 65535) |
1da177e4 LT |
531 | goto out_oversize; |
532 | ||
533 | /* Head of list must not be cloned. */ | |
14bbd6a5 | 534 | if (skb_unclone(head, GFP_ATOMIC)) |
1da177e4 LT |
535 | goto out_nomem; |
536 | ||
537 | /* If the first fragment is fragmented itself, we split | |
538 | * it to two chunks: the first with data and paged part | |
539 | * and the second, holding only fragments. */ | |
21dc3301 | 540 | if (skb_has_frag_list(head)) { |
1da177e4 LT |
541 | struct sk_buff *clone; |
542 | int i, plen = 0; | |
543 | ||
51456b29 IM |
544 | clone = alloc_skb(0, GFP_ATOMIC); |
545 | if (!clone) | |
1da177e4 LT |
546 | goto out_nomem; |
547 | clone->next = head->next; | |
548 | head->next = clone; | |
549 | skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; | |
d7fcf1a5 | 550 | skb_frag_list_init(head); |
9e903e08 ED |
551 | for (i = 0; i < skb_shinfo(head)->nr_frags; i++) |
552 | plen += skb_frag_size(&skb_shinfo(head)->frags[i]); | |
1da177e4 LT |
553 | clone->len = clone->data_len = head->data_len - plen; |
554 | head->data_len -= clone->len; | |
555 | head->len -= clone->len; | |
556 | clone->csum = 0; | |
557 | clone->ip_summed = head->ip_summed; | |
0e60d245 | 558 | add_frag_mem_limit(qp->q.net, clone->truesize); |
1da177e4 LT |
559 | } |
560 | ||
14fe22e3 | 561 | skb_shinfo(head)->frag_list = head->next; |
d56f90a7 | 562 | skb_push(head, head->data - skb_network_header(head)); |
1da177e4 | 563 | |
14fe22e3 FW |
564 | for (fp=head->next; fp; fp = fp->next) { |
565 | head->data_len += fp->len; | |
566 | head->len += fp->len; | |
1da177e4 LT |
567 | if (head->ip_summed != fp->ip_summed) |
568 | head->ip_summed = CHECKSUM_NONE; | |
84fa7933 | 569 | else if (head->ip_summed == CHECKSUM_COMPLETE) |
1da177e4 | 570 | head->csum = csum_add(head->csum, fp->csum); |
14fe22e3 | 571 | head->truesize += fp->truesize; |
1da177e4 | 572 | } |
5510b3c2 | 573 | sub_frag_mem_limit(qp->q.net, head->truesize); |
1da177e4 LT |
574 | |
575 | head->next = NULL; | |
576 | head->dev = dev; | |
5ab11c98 | 577 | head->tstamp = qp->q.stamp; |
d6b915e2 | 578 | IPCB(head)->frag_max_size = max(qp->max_df_size, qp->q.max_size); |
1da177e4 | 579 | |
eddc9ec5 | 580 | iph = ip_hdr(head); |
1da177e4 | 581 | iph->tot_len = htons(len); |
5173cc05 | 582 | iph->tos |= ecn; |
d6b915e2 FW |
583 | |
584 | /* When we set IP_DF on a refragmented skb we must also force a | |
585 | * call to ip_fragment to avoid forwarding a DF-skb of size s while | |
586 | * original sender only sent fragments of size f (where f < s). | |
587 | * | |
588 | * We only set DF/IPSKB_FRAG_PMTU if such DF fragment was the largest | |
589 | * frag seen to avoid sending tiny DF-fragments in case skb was built | |
590 | * from one very small df-fragment and one large non-df frag. | |
591 | */ | |
592 | if (qp->max_df_size == qp->q.max_size) { | |
593 | IPCB(head)->flags |= IPSKB_FRAG_PMTU; | |
594 | iph->frag_off = htons(IP_DF); | |
595 | } else { | |
596 | iph->frag_off = 0; | |
597 | } | |
598 | ||
0848f642 EHJ |
599 | ip_send_check(iph); |
600 | ||
b45386ef | 601 | __IP_INC_STATS(net, IPSTATS_MIB_REASMOKS); |
5ab11c98 | 602 | qp->q.fragments = NULL; |
d6bebca9 | 603 | qp->q.fragments_tail = NULL; |
1706d587 | 604 | return 0; |
1da177e4 LT |
605 | |
606 | out_nomem: | |
ba7a46f1 | 607 | net_dbg_ratelimited("queue_glue: no memory for gluing queue %p\n", qp); |
45542479 | 608 | err = -ENOMEM; |
1da177e4 LT |
609 | goto out_fail; |
610 | out_oversize: | |
4e722036 | 611 | net_info_ratelimited("Oversized IP packet from %pI4\n", &qp->q.key.v4.saddr); |
1da177e4 | 612 | out_fail: |
b45386ef | 613 | __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS); |
1706d587 | 614 | return err; |
1da177e4 LT |
615 | } |
616 | ||
617 | /* Process an incoming IP datagram fragment. */ | |
19bcf9f2 | 618 | int ip_defrag(struct net *net, struct sk_buff *skb, u32 user) |
1da177e4 | 619 | { |
9972f134 | 620 | struct net_device *dev = skb->dev ? : skb_dst(skb)->dev; |
385add90 | 621 | int vif = l3mdev_master_ifindex_rcu(dev); |
1da177e4 | 622 | struct ipq *qp; |
e905a9ed | 623 | |
b45386ef | 624 | __IP_INC_STATS(net, IPSTATS_MIB_REASMREQDS); |
8282f274 | 625 | skb_orphan(skb); |
1da177e4 | 626 | |
1da177e4 | 627 | /* Lookup (or create) queue header */ |
9972f134 | 628 | qp = ip_find(net, ip_hdr(skb), user, vif); |
00db4124 | 629 | if (qp) { |
1706d587 | 630 | int ret; |
1da177e4 | 631 | |
5ab11c98 | 632 | spin_lock(&qp->q.lock); |
1da177e4 | 633 | |
1706d587 | 634 | ret = ip_frag_queue(qp, skb); |
1da177e4 | 635 | |
5ab11c98 | 636 | spin_unlock(&qp->q.lock); |
4b6cb5d8 | 637 | ipq_put(qp); |
776c729e | 638 | return ret; |
1da177e4 LT |
639 | } |
640 | ||
b45386ef | 641 | __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS); |
1da177e4 | 642 | kfree_skb(skb); |
776c729e | 643 | return -ENOMEM; |
1da177e4 | 644 | } |
4bc2f18b | 645 | EXPORT_SYMBOL(ip_defrag); |
1da177e4 | 646 | |
19bcf9f2 | 647 | struct sk_buff *ip_check_defrag(struct net *net, struct sk_buff *skb, u32 user) |
bc416d97 | 648 | { |
1bf3751e | 649 | struct iphdr iph; |
3e32e733 | 650 | int netoff; |
bc416d97 ED |
651 | u32 len; |
652 | ||
653 | if (skb->protocol != htons(ETH_P_IP)) | |
654 | return skb; | |
655 | ||
3e32e733 AD |
656 | netoff = skb_network_offset(skb); |
657 | ||
658 | if (skb_copy_bits(skb, netoff, &iph, sizeof(iph)) < 0) | |
bc416d97 ED |
659 | return skb; |
660 | ||
1bf3751e | 661 | if (iph.ihl < 5 || iph.version != 4) |
bc416d97 | 662 | return skb; |
1bf3751e JB |
663 | |
664 | len = ntohs(iph.tot_len); | |
3e32e733 | 665 | if (skb->len < netoff + len || len < (iph.ihl * 4)) |
bc416d97 ED |
666 | return skb; |
667 | ||
1bf3751e | 668 | if (ip_is_fragment(&iph)) { |
bc416d97 ED |
669 | skb = skb_share_check(skb, GFP_ATOMIC); |
670 | if (skb) { | |
3e32e733 | 671 | if (!pskb_may_pull(skb, netoff + iph.ihl * 4)) |
1bf3751e | 672 | return skb; |
3e32e733 | 673 | if (pskb_trim_rcsum(skb, netoff + len)) |
bc416d97 ED |
674 | return skb; |
675 | memset(IPCB(skb), 0, sizeof(struct inet_skb_parm)); | |
19bcf9f2 | 676 | if (ip_defrag(net, skb, user)) |
bc416d97 | 677 | return NULL; |
7539fadc | 678 | skb_clear_hash(skb); |
bc416d97 ED |
679 | } |
680 | } | |
681 | return skb; | |
682 | } | |
683 | EXPORT_SYMBOL(ip_check_defrag); | |
684 | ||
8d8354d2 | 685 | #ifdef CONFIG_SYSCTL |
c88be42e | 686 | static long zero; |
8d8354d2 | 687 | |
0a64b4b8 | 688 | static struct ctl_table ip4_frags_ns_ctl_table[] = { |
8d8354d2 | 689 | { |
8d8354d2 | 690 | .procname = "ipfrag_high_thresh", |
e31e0bdc | 691 | .data = &init_net.ipv4.frags.high_thresh, |
c88be42e | 692 | .maxlen = sizeof(unsigned long), |
8d8354d2 | 693 | .mode = 0644, |
c88be42e | 694 | .proc_handler = proc_doulongvec_minmax, |
1bab4c75 | 695 | .extra1 = &init_net.ipv4.frags.low_thresh |
8d8354d2 PE |
696 | }, |
697 | { | |
8d8354d2 | 698 | .procname = "ipfrag_low_thresh", |
e31e0bdc | 699 | .data = &init_net.ipv4.frags.low_thresh, |
c88be42e | 700 | .maxlen = sizeof(unsigned long), |
8d8354d2 | 701 | .mode = 0644, |
c88be42e | 702 | .proc_handler = proc_doulongvec_minmax, |
1bab4c75 NA |
703 | .extra1 = &zero, |
704 | .extra2 = &init_net.ipv4.frags.high_thresh | |
8d8354d2 PE |
705 | }, |
706 | { | |
8d8354d2 | 707 | .procname = "ipfrag_time", |
b2fd5321 | 708 | .data = &init_net.ipv4.frags.timeout, |
8d8354d2 PE |
709 | .maxlen = sizeof(int), |
710 | .mode = 0644, | |
6d9f239a | 711 | .proc_handler = proc_dointvec_jiffies, |
8d8354d2 | 712 | }, |
0fbf4cb2 NB |
713 | { |
714 | .procname = "ipfrag_max_dist", | |
715 | .data = &init_net.ipv4.frags.max_dist, | |
716 | .maxlen = sizeof(int), | |
717 | .mode = 0644, | |
718 | .proc_handler = proc_dointvec_minmax, | |
719 | .extra1 = &zero | |
720 | }, | |
7d291ebb PE |
721 | { } |
722 | }; | |
723 | ||
e3a57d18 FW |
724 | /* secret interval has been deprecated */ |
725 | static int ip4_frags_secret_interval_unused; | |
7d291ebb | 726 | static struct ctl_table ip4_frags_ctl_table[] = { |
8d8354d2 | 727 | { |
8d8354d2 | 728 | .procname = "ipfrag_secret_interval", |
e3a57d18 | 729 | .data = &ip4_frags_secret_interval_unused, |
8d8354d2 PE |
730 | .maxlen = sizeof(int), |
731 | .mode = 0644, | |
6d9f239a | 732 | .proc_handler = proc_dointvec_jiffies, |
8d8354d2 | 733 | }, |
8d8354d2 PE |
734 | { } |
735 | }; | |
736 | ||
2c8c1e72 | 737 | static int __net_init ip4_frags_ns_ctl_register(struct net *net) |
8d8354d2 | 738 | { |
e4a2d5c2 | 739 | struct ctl_table *table; |
8d8354d2 PE |
740 | struct ctl_table_header *hdr; |
741 | ||
0a64b4b8 | 742 | table = ip4_frags_ns_ctl_table; |
09ad9bc7 | 743 | if (!net_eq(net, &init_net)) { |
0a64b4b8 | 744 | table = kmemdup(table, sizeof(ip4_frags_ns_ctl_table), GFP_KERNEL); |
51456b29 | 745 | if (!table) |
e4a2d5c2 PE |
746 | goto err_alloc; |
747 | ||
e31e0bdc | 748 | table[0].data = &net->ipv4.frags.high_thresh; |
1bab4c75 NA |
749 | table[0].extra1 = &net->ipv4.frags.low_thresh; |
750 | table[0].extra2 = &init_net.ipv4.frags.high_thresh; | |
e31e0bdc | 751 | table[1].data = &net->ipv4.frags.low_thresh; |
1bab4c75 | 752 | table[1].extra2 = &net->ipv4.frags.high_thresh; |
b2fd5321 | 753 | table[2].data = &net->ipv4.frags.timeout; |
0fbf4cb2 | 754 | table[3].data = &net->ipv4.frags.max_dist; |
e4a2d5c2 PE |
755 | } |
756 | ||
ec8f23ce | 757 | hdr = register_net_sysctl(net, "net/ipv4", table); |
51456b29 | 758 | if (!hdr) |
e4a2d5c2 PE |
759 | goto err_reg; |
760 | ||
761 | net->ipv4.frags_hdr = hdr; | |
762 | return 0; | |
763 | ||
764 | err_reg: | |
09ad9bc7 | 765 | if (!net_eq(net, &init_net)) |
e4a2d5c2 PE |
766 | kfree(table); |
767 | err_alloc: | |
768 | return -ENOMEM; | |
769 | } | |
770 | ||
2c8c1e72 | 771 | static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net) |
e4a2d5c2 PE |
772 | { |
773 | struct ctl_table *table; | |
774 | ||
775 | table = net->ipv4.frags_hdr->ctl_table_arg; | |
776 | unregister_net_sysctl_table(net->ipv4.frags_hdr); | |
777 | kfree(table); | |
8d8354d2 | 778 | } |
7d291ebb | 779 | |
57a02c39 | 780 | static void __init ip4_frags_ctl_register(void) |
7d291ebb | 781 | { |
43444757 | 782 | register_net_sysctl(&init_net, "net/ipv4", ip4_frags_ctl_table); |
7d291ebb | 783 | } |
8d8354d2 | 784 | #else |
aa1f731e | 785 | static int ip4_frags_ns_ctl_register(struct net *net) |
8d8354d2 PE |
786 | { |
787 | return 0; | |
788 | } | |
e4a2d5c2 | 789 | |
aa1f731e | 790 | static void ip4_frags_ns_ctl_unregister(struct net *net) |
e4a2d5c2 PE |
791 | { |
792 | } | |
7d291ebb | 793 | |
aa1f731e | 794 | static void __init ip4_frags_ctl_register(void) |
7d291ebb PE |
795 | { |
796 | } | |
8d8354d2 PE |
797 | #endif |
798 | ||
2c8c1e72 | 799 | static int __net_init ipv4_frags_init_net(struct net *net) |
8d8354d2 | 800 | { |
1f5c60ac ED |
801 | int res; |
802 | ||
77a24c31 TH |
803 | /* |
804 | * Fragment cache limits. We will commit 256K at one time. Should we | |
805 | * cross that limit we will prune down to 192K. This should cope with | |
806 | * even the most extreme cases without allowing an attacker to | |
807 | * measurably harm machine performance. | |
e31e0bdc | 808 | */ |
77a24c31 TH |
809 | net->ipv4.frags.high_thresh = 256 * 1024; |
810 | net->ipv4.frags.low_thresh = 192 * 1024; | |
b2fd5321 PE |
811 | /* |
812 | * Important NOTE! Fragment queue must be destroyed before MSL expires. | |
813 | * RFC791 is wrong proposing to prolongate timer each fragment arrival | |
814 | * by TTL. | |
815 | */ | |
816 | net->ipv4.frags.timeout = IP_FRAG_TIME; | |
817 | ||
0fbf4cb2 | 818 | net->ipv4.frags.max_dist = 64; |
9bdf9ca9 | 819 | net->ipv4.frags.f = &ip4_frags; |
0fbf4cb2 | 820 | |
1f5c60ac ED |
821 | res = inet_frags_init_net(&net->ipv4.frags); |
822 | if (res < 0) | |
823 | return res; | |
824 | res = ip4_frags_ns_ctl_register(net); | |
825 | if (res < 0) | |
9bdf9ca9 | 826 | inet_frags_exit_net(&net->ipv4.frags); |
1f5c60ac | 827 | return res; |
8d8354d2 PE |
828 | } |
829 | ||
2c8c1e72 | 830 | static void __net_exit ipv4_frags_exit_net(struct net *net) |
81566e83 | 831 | { |
0a64b4b8 | 832 | ip4_frags_ns_ctl_unregister(net); |
9bdf9ca9 | 833 | inet_frags_exit_net(&net->ipv4.frags); |
81566e83 PE |
834 | } |
835 | ||
836 | static struct pernet_operations ip4_frags_ops = { | |
837 | .init = ipv4_frags_init_net, | |
838 | .exit = ipv4_frags_exit_net, | |
839 | }; | |
840 | ||
4e722036 ED |
841 | |
842 | static u32 ip4_key_hashfn(const void *data, u32 len, u32 seed) | |
843 | { | |
844 | return jhash2(data, | |
845 | sizeof(struct frag_v4_compare_key) / sizeof(u32), seed); | |
846 | } | |
847 | ||
848 | static u32 ip4_obj_hashfn(const void *data, u32 len, u32 seed) | |
849 | { | |
850 | const struct inet_frag_queue *fq = data; | |
851 | ||
852 | return jhash2((const u32 *)&fq->key.v4, | |
853 | sizeof(struct frag_v4_compare_key) / sizeof(u32), seed); | |
854 | } | |
855 | ||
856 | static int ip4_obj_cmpfn(struct rhashtable_compare_arg *arg, const void *ptr) | |
857 | { | |
858 | const struct frag_v4_compare_key *key = arg->key; | |
859 | const struct inet_frag_queue *fq = ptr; | |
860 | ||
861 | return !!memcmp(&fq->key, key, sizeof(*key)); | |
862 | } | |
863 | ||
864 | static const struct rhashtable_params ip4_rhash_params = { | |
865 | .head_offset = offsetof(struct inet_frag_queue, node), | |
866 | .key_offset = offsetof(struct inet_frag_queue, key), | |
867 | .key_len = sizeof(struct frag_v4_compare_key), | |
868 | .hashfn = ip4_key_hashfn, | |
869 | .obj_hashfn = ip4_obj_hashfn, | |
870 | .obj_cmpfn = ip4_obj_cmpfn, | |
871 | .automatic_shrinking = true, | |
872 | }; | |
873 | ||
b7aa0bf7 | 874 | void __init ipfrag_init(void) |
1da177e4 | 875 | { |
c6fda282 | 876 | ip4_frags.constructor = ip4_frag_init; |
1e4b8287 | 877 | ip4_frags.destructor = ip4_frag_free; |
1e4b8287 | 878 | ip4_frags.qsize = sizeof(struct ipq); |
e521db9d | 879 | ip4_frags.frag_expire = ip_expire; |
d4ad4d22 | 880 | ip4_frags.frags_cache_name = ip_frag_cache_name; |
4e722036 | 881 | ip4_frags.rhash_params = ip4_rhash_params; |
d4ad4d22 NA |
882 | if (inet_frags_init(&ip4_frags)) |
883 | panic("IP: failed to allocate ip4_frags cache\n"); | |
72c16050 ED |
884 | ip4_frags_ctl_register(); |
885 | register_pernet_subsys(&ip4_frags_ops); | |
1da177e4 | 886 | } |