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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. | |
e905a9ed | 7 | * |
1da177e4 | 8 | * Authors: Fred N. van Kempen <waltje@uWalt.NL.Mugnet.ORG> |
113aa838 | 9 | * Alan Cox <alan@lxorguk.ukuu.org.uk> |
1da177e4 LT |
10 | * |
11 | * Fixes: | |
12 | * Alan Cox : Split from ip.c , see ip_input.c for history. | |
13 | * David S. Miller : Begin massive cleanup... | |
14 | * Andi Kleen : Add sysctls. | |
15 | * xxxx : Overlapfrag bug. | |
16 | * Ultima : ip_expire() kernel panic. | |
17 | * Bill Hawes : Frag accounting and evictor fixes. | |
18 | * John McDonald : 0 length frag bug. | |
19 | * Alexey Kuznetsov: SMP races, threading, cleanup. | |
20 | * Patrick McHardy : LRU queue of frag heads for evictor. | |
21 | */ | |
22 | ||
afd46503 JP |
23 | #define pr_fmt(fmt) "IPv4: " fmt |
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> | |
5a0e3ad6 | 37 | #include <linux/slab.h> |
e9017b55 SW |
38 | #include <net/route.h> |
39 | #include <net/dst.h> | |
1da177e4 LT |
40 | #include <net/sock.h> |
41 | #include <net/ip.h> | |
42 | #include <net/icmp.h> | |
43 | #include <net/checksum.h> | |
89cee8b1 | 44 | #include <net/inetpeer.h> |
5ab11c98 | 45 | #include <net/inet_frag.h> |
1da177e4 LT |
46 | #include <linux/tcp.h> |
47 | #include <linux/udp.h> | |
48 | #include <linux/inet.h> | |
49 | #include <linux/netfilter_ipv4.h> | |
6623e3b2 | 50 | #include <net/inet_ecn.h> |
1da177e4 LT |
51 | |
52 | /* NOTE. Logic of IP defragmentation is parallel to corresponding IPv6 | |
53 | * code now. If you change something here, _PLEASE_ update ipv6/reassembly.c | |
54 | * as well. Or notify me, at least. --ANK | |
55 | */ | |
56 | ||
8d8354d2 | 57 | static int sysctl_ipfrag_max_dist __read_mostly = 64; |
89cee8b1 | 58 | |
1da177e4 LT |
59 | struct ipfrag_skb_cb |
60 | { | |
61 | struct inet_skb_parm h; | |
62 | int offset; | |
63 | }; | |
64 | ||
fd3f8c4c | 65 | #define FRAG_CB(skb) ((struct ipfrag_skb_cb *)((skb)->cb)) |
1da177e4 LT |
66 | |
67 | /* Describe an entry in the "incomplete datagrams" queue. */ | |
68 | struct ipq { | |
5ab11c98 PE |
69 | struct inet_frag_queue q; |
70 | ||
1da177e4 | 71 | u32 user; |
18277770 AV |
72 | __be32 saddr; |
73 | __be32 daddr; | |
74 | __be16 id; | |
1da177e4 | 75 | u8 protocol; |
6623e3b2 | 76 | u8 ecn; /* RFC3168 support */ |
89cee8b1 HX |
77 | int iif; |
78 | unsigned int rid; | |
79 | struct inet_peer *peer; | |
1da177e4 LT |
80 | }; |
81 | ||
5173cc05 ED |
82 | /* RFC 3168 support : |
83 | * We want to check ECN values of all fragments, do detect invalid combinations. | |
84 | * In ipq->ecn, we store the OR value of each ip4_frag_ecn() fragment value. | |
85 | */ | |
1d1652cb DM |
86 | #define IPFRAG_ECN_NOT_ECT 0x01 /* one frag had ECN_NOT_ECT */ |
87 | #define IPFRAG_ECN_ECT_1 0x02 /* one frag had ECN_ECT_1 */ | |
88 | #define IPFRAG_ECN_ECT_0 0x04 /* one frag had ECN_ECT_0 */ | |
89 | #define IPFRAG_ECN_CE 0x08 /* one frag had ECN_CE */ | |
6623e3b2 ED |
90 | |
91 | static inline u8 ip4_frag_ecn(u8 tos) | |
92 | { | |
5173cc05 | 93 | return 1 << (tos & INET_ECN_MASK); |
6623e3b2 ED |
94 | } |
95 | ||
5173cc05 ED |
96 | /* Given the OR values of all fragments, apply RFC 3168 5.3 requirements |
97 | * Value : 0xff if frame should be dropped. | |
98 | * 0 or INET_ECN_CE value, to be ORed in to final iph->tos field | |
99 | */ | |
100 | static const u8 ip4_frag_ecn_table[16] = { | |
101 | /* at least one fragment had CE, and others ECT_0 or ECT_1 */ | |
102 | [IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0] = INET_ECN_CE, | |
103 | [IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1] = INET_ECN_CE, | |
104 | [IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = INET_ECN_CE, | |
105 | ||
106 | /* invalid combinations : drop frame */ | |
107 | [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE] = 0xff, | |
108 | [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0] = 0xff, | |
109 | [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_1] = 0xff, | |
110 | [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff, | |
111 | [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0] = 0xff, | |
112 | [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1] = 0xff, | |
113 | [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff, | |
114 | }; | |
115 | ||
7eb95156 | 116 | static struct inet_frags ip4_frags; |
1da177e4 | 117 | |
e5a2bb84 | 118 | int ip_frag_nqueues(struct net *net) |
7eb95156 | 119 | { |
e5a2bb84 | 120 | return net->ipv4.frags.nqueues; |
7eb95156 | 121 | } |
1da177e4 | 122 | |
6ddc0822 | 123 | int ip_frag_mem(struct net *net) |
7eb95156 | 124 | { |
6ddc0822 | 125 | return atomic_read(&net->ipv4.frags.mem); |
7eb95156 | 126 | } |
1da177e4 | 127 | |
1706d587 HX |
128 | static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, |
129 | struct net_device *dev); | |
130 | ||
c6fda282 PE |
131 | struct ip4_create_arg { |
132 | struct iphdr *iph; | |
133 | u32 user; | |
134 | }; | |
135 | ||
18277770 | 136 | static unsigned int ipqhashfn(__be16 id, __be32 saddr, __be32 daddr, u8 prot) |
1da177e4 | 137 | { |
18277770 AV |
138 | return jhash_3words((__force u32)id << 16 | prot, |
139 | (__force u32)saddr, (__force u32)daddr, | |
7eb95156 | 140 | ip4_frags.rnd) & (INETFRAGS_HASHSZ - 1); |
1da177e4 LT |
141 | } |
142 | ||
321a3a99 | 143 | static unsigned int ip4_hashfn(struct inet_frag_queue *q) |
1da177e4 | 144 | { |
321a3a99 | 145 | struct ipq *ipq; |
1da177e4 | 146 | |
321a3a99 PE |
147 | ipq = container_of(q, struct ipq, q); |
148 | return ipqhashfn(ipq->id, ipq->saddr, ipq->daddr, ipq->protocol); | |
1da177e4 LT |
149 | } |
150 | ||
cbc264ca | 151 | static bool ip4_frag_match(struct inet_frag_queue *q, void *a) |
abd6523d PE |
152 | { |
153 | struct ipq *qp; | |
154 | struct ip4_create_arg *arg = a; | |
155 | ||
156 | qp = container_of(q, struct ipq, q); | |
a02cec21 | 157 | return qp->id == arg->iph->id && |
cbc264ca ED |
158 | qp->saddr == arg->iph->saddr && |
159 | qp->daddr == arg->iph->daddr && | |
160 | qp->protocol == arg->iph->protocol && | |
161 | qp->user == arg->user; | |
abd6523d PE |
162 | } |
163 | ||
1da177e4 | 164 | /* Memory Tracking Functions. */ |
a95d8c88 | 165 | static void frag_kfree_skb(struct netns_frags *nf, struct sk_buff *skb) |
1da177e4 | 166 | { |
6ddc0822 | 167 | atomic_sub(skb->truesize, &nf->mem); |
1da177e4 LT |
168 | kfree_skb(skb); |
169 | } | |
170 | ||
c6fda282 PE |
171 | static void ip4_frag_init(struct inet_frag_queue *q, void *a) |
172 | { | |
173 | struct ipq *qp = container_of(q, struct ipq, q); | |
54db0cc2 G |
174 | struct netns_ipv4 *ipv4 = container_of(q->net, struct netns_ipv4, |
175 | frags); | |
176 | struct net *net = container_of(ipv4, struct net, ipv4); | |
177 | ||
c6fda282 PE |
178 | struct ip4_create_arg *arg = a; |
179 | ||
180 | qp->protocol = arg->iph->protocol; | |
181 | qp->id = arg->iph->id; | |
6623e3b2 | 182 | qp->ecn = ip4_frag_ecn(arg->iph->tos); |
c6fda282 PE |
183 | qp->saddr = arg->iph->saddr; |
184 | qp->daddr = arg->iph->daddr; | |
185 | qp->user = arg->user; | |
186 | qp->peer = sysctl_ipfrag_max_dist ? | |
54db0cc2 | 187 | inet_getpeer_v4(net, arg->iph->saddr, 1) : NULL; |
c6fda282 PE |
188 | } |
189 | ||
1e4b8287 | 190 | static __inline__ void ip4_frag_free(struct inet_frag_queue *q) |
1da177e4 | 191 | { |
1e4b8287 PE |
192 | struct ipq *qp; |
193 | ||
194 | qp = container_of(q, struct ipq, q); | |
195 | if (qp->peer) | |
196 | inet_putpeer(qp->peer); | |
1da177e4 LT |
197 | } |
198 | ||
1da177e4 LT |
199 | |
200 | /* Destruction primitives. */ | |
201 | ||
4b6cb5d8 | 202 | static __inline__ void ipq_put(struct ipq *ipq) |
1da177e4 | 203 | { |
762cc408 | 204 | inet_frag_put(&ipq->q, &ip4_frags); |
1da177e4 LT |
205 | } |
206 | ||
207 | /* Kill ipq entry. It is not destroyed immediately, | |
208 | * because caller (and someone more) holds reference count. | |
209 | */ | |
210 | static void ipq_kill(struct ipq *ipq) | |
211 | { | |
277e650d | 212 | inet_frag_kill(&ipq->q, &ip4_frags); |
1da177e4 LT |
213 | } |
214 | ||
e905a9ed | 215 | /* Memory limiting on fragments. Evictor trashes the oldest |
1da177e4 LT |
216 | * fragment queue until we are back under the threshold. |
217 | */ | |
6ddc0822 | 218 | static void ip_evictor(struct net *net) |
1da177e4 | 219 | { |
8e7999c4 PE |
220 | int evicted; |
221 | ||
6ddc0822 | 222 | evicted = inet_frag_evictor(&net->ipv4.frags, &ip4_frags); |
8e7999c4 | 223 | if (evicted) |
c5346fe3 | 224 | IP_ADD_STATS_BH(net, IPSTATS_MIB_REASMFAILS, evicted); |
1da177e4 LT |
225 | } |
226 | ||
227 | /* | |
228 | * Oops, a fragment queue timed out. Kill it and send an ICMP reply. | |
229 | */ | |
230 | static void ip_expire(unsigned long arg) | |
231 | { | |
e521db9d | 232 | struct ipq *qp; |
84a3aa00 | 233 | struct net *net; |
e521db9d PE |
234 | |
235 | qp = container_of((struct inet_frag_queue *) arg, struct ipq, q); | |
84a3aa00 | 236 | net = container_of(qp->q.net, struct net, ipv4.frags); |
1da177e4 | 237 | |
5ab11c98 | 238 | spin_lock(&qp->q.lock); |
1da177e4 | 239 | |
bc578a54 | 240 | if (qp->q.last_in & INET_FRAG_COMPLETE) |
1da177e4 LT |
241 | goto out; |
242 | ||
243 | ipq_kill(qp); | |
244 | ||
7c73a6fa PE |
245 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMTIMEOUT); |
246 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); | |
1da177e4 | 247 | |
bc578a54 | 248 | if ((qp->q.last_in & INET_FRAG_FIRST_IN) && qp->q.fragments != NULL) { |
5ab11c98 | 249 | struct sk_buff *head = qp->q.fragments; |
64f3b9e2 ED |
250 | const struct iphdr *iph; |
251 | int err; | |
cb84663e | 252 | |
69df9d59 ED |
253 | rcu_read_lock(); |
254 | head->dev = dev_get_by_index_rcu(net, qp->iif); | |
e9017b55 SW |
255 | if (!head->dev) |
256 | goto out_rcu_unlock; | |
257 | ||
64f3b9e2 ED |
258 | /* skb dst is stale, drop it, and perform route lookup again */ |
259 | skb_dst_drop(head); | |
260 | iph = ip_hdr(head); | |
261 | err = ip_route_input_noref(head, iph->daddr, iph->saddr, | |
262 | iph->tos, head->dev); | |
263 | if (err) | |
264 | goto out_rcu_unlock; | |
265 | ||
e9017b55 | 266 | /* |
64f3b9e2 ED |
267 | * Only an end host needs to send an ICMP |
268 | * "Fragment Reassembly Timeout" message, per RFC792. | |
e9017b55 | 269 | */ |
595fc71b DM |
270 | if (qp->user == IP_DEFRAG_AF_PACKET || |
271 | (qp->user == IP_DEFRAG_CONNTRACK_IN && | |
272 | skb_rtable(head)->rt_type != RTN_LOCAL)) | |
64f3b9e2 ED |
273 | goto out_rcu_unlock; |
274 | ||
e9017b55 SW |
275 | |
276 | /* Send an ICMP "Fragment Reassembly Timeout" message. */ | |
277 | icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0); | |
e9017b55 | 278 | out_rcu_unlock: |
d1c9ae6d PM |
279 | rcu_read_unlock(); |
280 | } | |
1da177e4 | 281 | out: |
5ab11c98 | 282 | spin_unlock(&qp->q.lock); |
4b6cb5d8 | 283 | ipq_put(qp); |
1da177e4 LT |
284 | } |
285 | ||
abd6523d PE |
286 | /* Find the correct entry in the "incomplete datagrams" queue for |
287 | * this IP datagram, and create new one, if nothing is found. | |
288 | */ | |
ac18e750 | 289 | static inline struct ipq *ip_find(struct net *net, struct iphdr *iph, u32 user) |
1da177e4 | 290 | { |
c6fda282 PE |
291 | struct inet_frag_queue *q; |
292 | struct ip4_create_arg arg; | |
abd6523d | 293 | unsigned int hash; |
1da177e4 | 294 | |
c6fda282 PE |
295 | arg.iph = iph; |
296 | arg.user = user; | |
9a375803 PE |
297 | |
298 | read_lock(&ip4_frags.lock); | |
abd6523d | 299 | hash = ipqhashfn(iph->id, iph->saddr, iph->daddr, iph->protocol); |
1da177e4 | 300 | |
ac18e750 | 301 | q = inet_frag_find(&net->ipv4.frags, &ip4_frags, &arg, hash); |
c6fda282 PE |
302 | if (q == NULL) |
303 | goto out_nomem; | |
1da177e4 | 304 | |
c6fda282 | 305 | return container_of(q, struct ipq, q); |
1da177e4 LT |
306 | |
307 | out_nomem: | |
afd46503 | 308 | LIMIT_NETDEBUG(KERN_ERR pr_fmt("ip_frag_create: no memory left !\n")); |
1da177e4 LT |
309 | return NULL; |
310 | } | |
311 | ||
89cee8b1 HX |
312 | /* Is the fragment too far ahead to be part of ipq? */ |
313 | static inline int ip_frag_too_far(struct ipq *qp) | |
314 | { | |
315 | struct inet_peer *peer = qp->peer; | |
316 | unsigned int max = sysctl_ipfrag_max_dist; | |
317 | unsigned int start, end; | |
318 | ||
319 | int rc; | |
320 | ||
321 | if (!peer || !max) | |
322 | return 0; | |
323 | ||
324 | start = qp->rid; | |
325 | end = atomic_inc_return(&peer->rid); | |
326 | qp->rid = end; | |
327 | ||
5ab11c98 | 328 | rc = qp->q.fragments && (end - start) > max; |
89cee8b1 HX |
329 | |
330 | if (rc) { | |
7c73a6fa PE |
331 | struct net *net; |
332 | ||
333 | net = container_of(qp->q.net, struct net, ipv4.frags); | |
334 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); | |
89cee8b1 HX |
335 | } |
336 | ||
337 | return rc; | |
338 | } | |
339 | ||
340 | static int ip_frag_reinit(struct ipq *qp) | |
341 | { | |
342 | struct sk_buff *fp; | |
343 | ||
b2fd5321 | 344 | if (!mod_timer(&qp->q.timer, jiffies + qp->q.net->timeout)) { |
5ab11c98 | 345 | atomic_inc(&qp->q.refcnt); |
89cee8b1 HX |
346 | return -ETIMEDOUT; |
347 | } | |
348 | ||
5ab11c98 | 349 | fp = qp->q.fragments; |
89cee8b1 HX |
350 | do { |
351 | struct sk_buff *xp = fp->next; | |
a95d8c88 | 352 | frag_kfree_skb(qp->q.net, fp); |
89cee8b1 HX |
353 | fp = xp; |
354 | } while (fp); | |
355 | ||
5ab11c98 PE |
356 | qp->q.last_in = 0; |
357 | qp->q.len = 0; | |
358 | qp->q.meat = 0; | |
359 | qp->q.fragments = NULL; | |
d6bebca9 | 360 | qp->q.fragments_tail = NULL; |
89cee8b1 | 361 | qp->iif = 0; |
6623e3b2 | 362 | qp->ecn = 0; |
89cee8b1 HX |
363 | |
364 | return 0; | |
365 | } | |
366 | ||
1da177e4 | 367 | /* Add new segment to existing queue. */ |
1706d587 | 368 | static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) |
1da177e4 LT |
369 | { |
370 | struct sk_buff *prev, *next; | |
1706d587 | 371 | struct net_device *dev; |
1da177e4 LT |
372 | int flags, offset; |
373 | int ihl, end; | |
1706d587 | 374 | int err = -ENOENT; |
6623e3b2 | 375 | u8 ecn; |
1da177e4 | 376 | |
bc578a54 | 377 | if (qp->q.last_in & INET_FRAG_COMPLETE) |
1da177e4 LT |
378 | goto err; |
379 | ||
89cee8b1 | 380 | if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) && |
1706d587 HX |
381 | unlikely(ip_frag_too_far(qp)) && |
382 | unlikely(err = ip_frag_reinit(qp))) { | |
89cee8b1 HX |
383 | ipq_kill(qp); |
384 | goto err; | |
385 | } | |
386 | ||
6623e3b2 | 387 | ecn = ip4_frag_ecn(ip_hdr(skb)->tos); |
eddc9ec5 | 388 | offset = ntohs(ip_hdr(skb)->frag_off); |
1da177e4 LT |
389 | flags = offset & ~IP_OFFSET; |
390 | offset &= IP_OFFSET; | |
391 | offset <<= 3; /* offset is in 8-byte chunks */ | |
c9bdd4b5 | 392 | ihl = ip_hdrlen(skb); |
1da177e4 LT |
393 | |
394 | /* Determine the position of this fragment. */ | |
e905a9ed | 395 | end = offset + skb->len - ihl; |
1706d587 | 396 | err = -EINVAL; |
1da177e4 LT |
397 | |
398 | /* Is this the final fragment? */ | |
399 | if ((flags & IP_MF) == 0) { | |
400 | /* If we already have some bits beyond end | |
42b2aa86 | 401 | * or have different end, the segment is corrupted. |
1da177e4 | 402 | */ |
5ab11c98 | 403 | if (end < qp->q.len || |
bc578a54 | 404 | ((qp->q.last_in & INET_FRAG_LAST_IN) && end != qp->q.len)) |
1da177e4 | 405 | goto err; |
bc578a54 | 406 | qp->q.last_in |= INET_FRAG_LAST_IN; |
5ab11c98 | 407 | qp->q.len = end; |
1da177e4 LT |
408 | } else { |
409 | if (end&7) { | |
410 | end &= ~7; | |
411 | if (skb->ip_summed != CHECKSUM_UNNECESSARY) | |
412 | skb->ip_summed = CHECKSUM_NONE; | |
413 | } | |
5ab11c98 | 414 | if (end > qp->q.len) { |
1da177e4 | 415 | /* Some bits beyond end -> corruption. */ |
bc578a54 | 416 | if (qp->q.last_in & INET_FRAG_LAST_IN) |
1da177e4 | 417 | goto err; |
5ab11c98 | 418 | qp->q.len = end; |
1da177e4 LT |
419 | } |
420 | } | |
421 | if (end == offset) | |
422 | goto err; | |
423 | ||
1706d587 | 424 | err = -ENOMEM; |
1da177e4 LT |
425 | if (pskb_pull(skb, ihl) == NULL) |
426 | goto err; | |
1706d587 HX |
427 | |
428 | err = pskb_trim_rcsum(skb, end - offset); | |
429 | if (err) | |
1da177e4 LT |
430 | goto err; |
431 | ||
432 | /* Find out which fragments are in front and at the back of us | |
433 | * in the chain of fragments so far. We must know where to put | |
434 | * this fragment, right? | |
435 | */ | |
d6bebca9 CG |
436 | prev = qp->q.fragments_tail; |
437 | if (!prev || FRAG_CB(prev)->offset < offset) { | |
438 | next = NULL; | |
439 | goto found; | |
440 | } | |
1da177e4 | 441 | prev = NULL; |
5ab11c98 | 442 | for (next = qp->q.fragments; next != NULL; next = next->next) { |
1da177e4 LT |
443 | if (FRAG_CB(next)->offset >= offset) |
444 | break; /* bingo! */ | |
445 | prev = next; | |
446 | } | |
447 | ||
d6bebca9 | 448 | found: |
1da177e4 LT |
449 | /* We found where to put this one. Check for overlap with |
450 | * preceding fragment, and, if needed, align things so that | |
451 | * any overlaps are eliminated. | |
452 | */ | |
453 | if (prev) { | |
454 | int i = (FRAG_CB(prev)->offset + prev->len) - offset; | |
455 | ||
456 | if (i > 0) { | |
457 | offset += i; | |
1706d587 | 458 | err = -EINVAL; |
1da177e4 LT |
459 | if (end <= offset) |
460 | goto err; | |
1706d587 | 461 | err = -ENOMEM; |
1da177e4 LT |
462 | if (!pskb_pull(skb, i)) |
463 | goto err; | |
464 | if (skb->ip_summed != CHECKSUM_UNNECESSARY) | |
465 | skb->ip_summed = CHECKSUM_NONE; | |
466 | } | |
467 | } | |
468 | ||
1706d587 HX |
469 | err = -ENOMEM; |
470 | ||
1da177e4 LT |
471 | while (next && FRAG_CB(next)->offset < end) { |
472 | int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */ | |
473 | ||
474 | if (i < next->len) { | |
475 | /* Eat head of the next overlapped fragment | |
476 | * and leave the loop. The next ones cannot overlap. | |
477 | */ | |
478 | if (!pskb_pull(next, i)) | |
479 | goto err; | |
480 | FRAG_CB(next)->offset += i; | |
5ab11c98 | 481 | qp->q.meat -= i; |
1da177e4 LT |
482 | if (next->ip_summed != CHECKSUM_UNNECESSARY) |
483 | next->ip_summed = CHECKSUM_NONE; | |
484 | break; | |
485 | } else { | |
486 | struct sk_buff *free_it = next; | |
487 | ||
47c6bf77 | 488 | /* Old fragment is completely overridden with |
1da177e4 LT |
489 | * new one drop it. |
490 | */ | |
491 | next = next->next; | |
492 | ||
493 | if (prev) | |
494 | prev->next = next; | |
495 | else | |
5ab11c98 | 496 | qp->q.fragments = next; |
1da177e4 | 497 | |
5ab11c98 | 498 | qp->q.meat -= free_it->len; |
a95d8c88 | 499 | frag_kfree_skb(qp->q.net, free_it); |
1da177e4 LT |
500 | } |
501 | } | |
502 | ||
503 | FRAG_CB(skb)->offset = offset; | |
504 | ||
505 | /* Insert this fragment in the chain of fragments. */ | |
506 | skb->next = next; | |
d6bebca9 CG |
507 | if (!next) |
508 | qp->q.fragments_tail = skb; | |
1da177e4 LT |
509 | if (prev) |
510 | prev->next = skb; | |
511 | else | |
5ab11c98 | 512 | qp->q.fragments = skb; |
1da177e4 | 513 | |
1706d587 HX |
514 | dev = skb->dev; |
515 | if (dev) { | |
516 | qp->iif = dev->ifindex; | |
517 | skb->dev = NULL; | |
518 | } | |
5ab11c98 PE |
519 | qp->q.stamp = skb->tstamp; |
520 | qp->q.meat += skb->len; | |
6623e3b2 | 521 | qp->ecn |= ecn; |
6ddc0822 | 522 | atomic_add(skb->truesize, &qp->q.net->mem); |
1da177e4 | 523 | if (offset == 0) |
bc578a54 | 524 | qp->q.last_in |= INET_FRAG_FIRST_IN; |
1da177e4 | 525 | |
bc578a54 JP |
526 | if (qp->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && |
527 | qp->q.meat == qp->q.len) | |
1706d587 HX |
528 | return ip_frag_reasm(qp, prev, dev); |
529 | ||
7eb95156 | 530 | write_lock(&ip4_frags.lock); |
3140c25c | 531 | list_move_tail(&qp->q.lru_list, &qp->q.net->lru_list); |
7eb95156 | 532 | write_unlock(&ip4_frags.lock); |
1706d587 | 533 | return -EINPROGRESS; |
1da177e4 LT |
534 | |
535 | err: | |
536 | kfree_skb(skb); | |
1706d587 | 537 | return err; |
1da177e4 LT |
538 | } |
539 | ||
540 | ||
541 | /* Build a new IP datagram from all its fragments. */ | |
542 | ||
1706d587 HX |
543 | static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, |
544 | struct net_device *dev) | |
1da177e4 | 545 | { |
2bad35b7 | 546 | struct net *net = container_of(qp->q.net, struct net, ipv4.frags); |
1da177e4 | 547 | struct iphdr *iph; |
5ab11c98 | 548 | struct sk_buff *fp, *head = qp->q.fragments; |
1da177e4 LT |
549 | int len; |
550 | int ihlen; | |
1706d587 | 551 | int err; |
3cc49492 | 552 | int sum_truesize; |
5173cc05 | 553 | u8 ecn; |
1da177e4 LT |
554 | |
555 | ipq_kill(qp); | |
556 | ||
5173cc05 ED |
557 | ecn = ip4_frag_ecn_table[qp->ecn]; |
558 | if (unlikely(ecn == 0xff)) { | |
559 | err = -EINVAL; | |
560 | goto out_fail; | |
561 | } | |
1706d587 HX |
562 | /* Make the one we just received the head. */ |
563 | if (prev) { | |
564 | head = prev->next; | |
565 | fp = skb_clone(head, GFP_ATOMIC); | |
1706d587 HX |
566 | if (!fp) |
567 | goto out_nomem; | |
568 | ||
569 | fp->next = head->next; | |
d6bebca9 CG |
570 | if (!fp->next) |
571 | qp->q.fragments_tail = fp; | |
1706d587 HX |
572 | prev->next = fp; |
573 | ||
5ab11c98 PE |
574 | skb_morph(head, qp->q.fragments); |
575 | head->next = qp->q.fragments->next; | |
1706d587 | 576 | |
cbf8f7bb | 577 | consume_skb(qp->q.fragments); |
5ab11c98 | 578 | qp->q.fragments = head; |
1706d587 HX |
579 | } |
580 | ||
547b792c IJ |
581 | WARN_ON(head == NULL); |
582 | WARN_ON(FRAG_CB(head)->offset != 0); | |
1da177e4 LT |
583 | |
584 | /* Allocate a new buffer for the datagram. */ | |
c9bdd4b5 | 585 | ihlen = ip_hdrlen(head); |
5ab11c98 | 586 | len = ihlen + qp->q.len; |
1da177e4 | 587 | |
1706d587 | 588 | err = -E2BIG; |
132adf54 | 589 | if (len > 65535) |
1da177e4 LT |
590 | goto out_oversize; |
591 | ||
592 | /* Head of list must not be cloned. */ | |
593 | if (skb_cloned(head) && pskb_expand_head(head, 0, 0, GFP_ATOMIC)) | |
594 | goto out_nomem; | |
595 | ||
596 | /* If the first fragment is fragmented itself, we split | |
597 | * it to two chunks: the first with data and paged part | |
598 | * and the second, holding only fragments. */ | |
21dc3301 | 599 | if (skb_has_frag_list(head)) { |
1da177e4 LT |
600 | struct sk_buff *clone; |
601 | int i, plen = 0; | |
602 | ||
603 | if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) | |
604 | goto out_nomem; | |
605 | clone->next = head->next; | |
606 | head->next = clone; | |
607 | skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; | |
d7fcf1a5 | 608 | skb_frag_list_init(head); |
9e903e08 ED |
609 | for (i = 0; i < skb_shinfo(head)->nr_frags; i++) |
610 | plen += skb_frag_size(&skb_shinfo(head)->frags[i]); | |
1da177e4 LT |
611 | clone->len = clone->data_len = head->data_len - plen; |
612 | head->data_len -= clone->len; | |
613 | head->len -= clone->len; | |
614 | clone->csum = 0; | |
615 | clone->ip_summed = head->ip_summed; | |
6ddc0822 | 616 | atomic_add(clone->truesize, &qp->q.net->mem); |
1da177e4 LT |
617 | } |
618 | ||
d56f90a7 | 619 | skb_push(head, head->data - skb_network_header(head)); |
1da177e4 | 620 | |
3cc49492 ED |
621 | sum_truesize = head->truesize; |
622 | for (fp = head->next; fp;) { | |
623 | bool headstolen; | |
624 | int delta; | |
625 | struct sk_buff *next = fp->next; | |
626 | ||
627 | sum_truesize += fp->truesize; | |
1da177e4 LT |
628 | if (head->ip_summed != fp->ip_summed) |
629 | head->ip_summed = CHECKSUM_NONE; | |
84fa7933 | 630 | else if (head->ip_summed == CHECKSUM_COMPLETE) |
1da177e4 | 631 | head->csum = csum_add(head->csum, fp->csum); |
3cc49492 ED |
632 | |
633 | if (skb_try_coalesce(head, fp, &headstolen, &delta)) { | |
634 | kfree_skb_partial(fp, headstolen); | |
635 | } else { | |
636 | if (!skb_shinfo(head)->frag_list) | |
637 | skb_shinfo(head)->frag_list = fp; | |
638 | head->data_len += fp->len; | |
639 | head->len += fp->len; | |
640 | head->truesize += fp->truesize; | |
641 | } | |
642 | fp = next; | |
1da177e4 | 643 | } |
3cc49492 | 644 | atomic_sub(sum_truesize, &qp->q.net->mem); |
1da177e4 LT |
645 | |
646 | head->next = NULL; | |
647 | head->dev = dev; | |
5ab11c98 | 648 | head->tstamp = qp->q.stamp; |
1da177e4 | 649 | |
eddc9ec5 | 650 | iph = ip_hdr(head); |
1da177e4 LT |
651 | iph->frag_off = 0; |
652 | iph->tot_len = htons(len); | |
5173cc05 | 653 | iph->tos |= ecn; |
2bad35b7 | 654 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMOKS); |
5ab11c98 | 655 | qp->q.fragments = NULL; |
d6bebca9 | 656 | qp->q.fragments_tail = NULL; |
1706d587 | 657 | return 0; |
1da177e4 LT |
658 | |
659 | out_nomem: | |
afd46503 JP |
660 | LIMIT_NETDEBUG(KERN_ERR pr_fmt("queue_glue: no memory for gluing queue %p\n"), |
661 | qp); | |
45542479 | 662 | err = -ENOMEM; |
1da177e4 LT |
663 | goto out_fail; |
664 | out_oversize: | |
e87cc472 | 665 | net_info_ratelimited("Oversized IP packet from %pI4\n", &qp->saddr); |
1da177e4 | 666 | out_fail: |
bbf31bf1 | 667 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); |
1706d587 | 668 | return err; |
1da177e4 LT |
669 | } |
670 | ||
671 | /* Process an incoming IP datagram fragment. */ | |
776c729e | 672 | int ip_defrag(struct sk_buff *skb, u32 user) |
1da177e4 | 673 | { |
1da177e4 | 674 | struct ipq *qp; |
ac18e750 | 675 | struct net *net; |
e905a9ed | 676 | |
adf30907 | 677 | net = skb->dev ? dev_net(skb->dev) : dev_net(skb_dst(skb)->dev); |
7c73a6fa | 678 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMREQDS); |
1da177e4 LT |
679 | |
680 | /* Start by cleaning up the memory. */ | |
e31e0bdc | 681 | if (atomic_read(&net->ipv4.frags.mem) > net->ipv4.frags.high_thresh) |
6ddc0822 | 682 | ip_evictor(net); |
1da177e4 | 683 | |
1da177e4 | 684 | /* Lookup (or create) queue header */ |
ac18e750 | 685 | if ((qp = ip_find(net, ip_hdr(skb), user)) != NULL) { |
1706d587 | 686 | int ret; |
1da177e4 | 687 | |
5ab11c98 | 688 | spin_lock(&qp->q.lock); |
1da177e4 | 689 | |
1706d587 | 690 | ret = ip_frag_queue(qp, skb); |
1da177e4 | 691 | |
5ab11c98 | 692 | spin_unlock(&qp->q.lock); |
4b6cb5d8 | 693 | ipq_put(qp); |
776c729e | 694 | return ret; |
1da177e4 LT |
695 | } |
696 | ||
7c73a6fa | 697 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); |
1da177e4 | 698 | kfree_skb(skb); |
776c729e | 699 | return -ENOMEM; |
1da177e4 | 700 | } |
4bc2f18b | 701 | EXPORT_SYMBOL(ip_defrag); |
1da177e4 | 702 | |
bc416d97 ED |
703 | struct sk_buff *ip_check_defrag(struct sk_buff *skb, u32 user) |
704 | { | |
705 | const struct iphdr *iph; | |
706 | u32 len; | |
707 | ||
708 | if (skb->protocol != htons(ETH_P_IP)) | |
709 | return skb; | |
710 | ||
711 | if (!pskb_may_pull(skb, sizeof(struct iphdr))) | |
712 | return skb; | |
713 | ||
714 | iph = ip_hdr(skb); | |
715 | if (iph->ihl < 5 || iph->version != 4) | |
716 | return skb; | |
717 | if (!pskb_may_pull(skb, iph->ihl*4)) | |
718 | return skb; | |
719 | iph = ip_hdr(skb); | |
720 | len = ntohs(iph->tot_len); | |
721 | if (skb->len < len || len < (iph->ihl * 4)) | |
722 | return skb; | |
723 | ||
724 | if (ip_is_fragment(ip_hdr(skb))) { | |
725 | skb = skb_share_check(skb, GFP_ATOMIC); | |
726 | if (skb) { | |
727 | if (pskb_trim_rcsum(skb, len)) | |
728 | return skb; | |
729 | memset(IPCB(skb), 0, sizeof(struct inet_skb_parm)); | |
730 | if (ip_defrag(skb, user)) | |
731 | return NULL; | |
732 | skb->rxhash = 0; | |
733 | } | |
734 | } | |
735 | return skb; | |
736 | } | |
737 | EXPORT_SYMBOL(ip_check_defrag); | |
738 | ||
8d8354d2 PE |
739 | #ifdef CONFIG_SYSCTL |
740 | static int zero; | |
741 | ||
0a64b4b8 | 742 | static struct ctl_table ip4_frags_ns_ctl_table[] = { |
8d8354d2 | 743 | { |
8d8354d2 | 744 | .procname = "ipfrag_high_thresh", |
e31e0bdc | 745 | .data = &init_net.ipv4.frags.high_thresh, |
8d8354d2 PE |
746 | .maxlen = sizeof(int), |
747 | .mode = 0644, | |
6d9f239a | 748 | .proc_handler = proc_dointvec |
8d8354d2 PE |
749 | }, |
750 | { | |
8d8354d2 | 751 | .procname = "ipfrag_low_thresh", |
e31e0bdc | 752 | .data = &init_net.ipv4.frags.low_thresh, |
8d8354d2 PE |
753 | .maxlen = sizeof(int), |
754 | .mode = 0644, | |
6d9f239a | 755 | .proc_handler = proc_dointvec |
8d8354d2 PE |
756 | }, |
757 | { | |
8d8354d2 | 758 | .procname = "ipfrag_time", |
b2fd5321 | 759 | .data = &init_net.ipv4.frags.timeout, |
8d8354d2 PE |
760 | .maxlen = sizeof(int), |
761 | .mode = 0644, | |
6d9f239a | 762 | .proc_handler = proc_dointvec_jiffies, |
8d8354d2 | 763 | }, |
7d291ebb PE |
764 | { } |
765 | }; | |
766 | ||
767 | static struct ctl_table ip4_frags_ctl_table[] = { | |
8d8354d2 | 768 | { |
8d8354d2 | 769 | .procname = "ipfrag_secret_interval", |
3b4bc4a2 | 770 | .data = &ip4_frags.secret_interval, |
8d8354d2 PE |
771 | .maxlen = sizeof(int), |
772 | .mode = 0644, | |
6d9f239a | 773 | .proc_handler = proc_dointvec_jiffies, |
8d8354d2 PE |
774 | }, |
775 | { | |
776 | .procname = "ipfrag_max_dist", | |
777 | .data = &sysctl_ipfrag_max_dist, | |
778 | .maxlen = sizeof(int), | |
779 | .mode = 0644, | |
6d9f239a | 780 | .proc_handler = proc_dointvec_minmax, |
8d8354d2 PE |
781 | .extra1 = &zero |
782 | }, | |
783 | { } | |
784 | }; | |
785 | ||
2c8c1e72 | 786 | static int __net_init ip4_frags_ns_ctl_register(struct net *net) |
8d8354d2 | 787 | { |
e4a2d5c2 | 788 | struct ctl_table *table; |
8d8354d2 PE |
789 | struct ctl_table_header *hdr; |
790 | ||
0a64b4b8 | 791 | table = ip4_frags_ns_ctl_table; |
09ad9bc7 | 792 | if (!net_eq(net, &init_net)) { |
0a64b4b8 | 793 | table = kmemdup(table, sizeof(ip4_frags_ns_ctl_table), GFP_KERNEL); |
e4a2d5c2 PE |
794 | if (table == NULL) |
795 | goto err_alloc; | |
796 | ||
e31e0bdc PE |
797 | table[0].data = &net->ipv4.frags.high_thresh; |
798 | table[1].data = &net->ipv4.frags.low_thresh; | |
b2fd5321 | 799 | table[2].data = &net->ipv4.frags.timeout; |
e4a2d5c2 PE |
800 | } |
801 | ||
ec8f23ce | 802 | hdr = register_net_sysctl(net, "net/ipv4", table); |
e4a2d5c2 PE |
803 | if (hdr == NULL) |
804 | goto err_reg; | |
805 | ||
806 | net->ipv4.frags_hdr = hdr; | |
807 | return 0; | |
808 | ||
809 | err_reg: | |
09ad9bc7 | 810 | if (!net_eq(net, &init_net)) |
e4a2d5c2 PE |
811 | kfree(table); |
812 | err_alloc: | |
813 | return -ENOMEM; | |
814 | } | |
815 | ||
2c8c1e72 | 816 | static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net) |
e4a2d5c2 PE |
817 | { |
818 | struct ctl_table *table; | |
819 | ||
820 | table = net->ipv4.frags_hdr->ctl_table_arg; | |
821 | unregister_net_sysctl_table(net->ipv4.frags_hdr); | |
822 | kfree(table); | |
8d8354d2 | 823 | } |
7d291ebb PE |
824 | |
825 | static void ip4_frags_ctl_register(void) | |
826 | { | |
43444757 | 827 | register_net_sysctl(&init_net, "net/ipv4", ip4_frags_ctl_table); |
7d291ebb | 828 | } |
8d8354d2 | 829 | #else |
0a64b4b8 | 830 | static inline int ip4_frags_ns_ctl_register(struct net *net) |
8d8354d2 PE |
831 | { |
832 | return 0; | |
833 | } | |
e4a2d5c2 | 834 | |
0a64b4b8 | 835 | static inline void ip4_frags_ns_ctl_unregister(struct net *net) |
e4a2d5c2 PE |
836 | { |
837 | } | |
7d291ebb PE |
838 | |
839 | static inline void ip4_frags_ctl_register(void) | |
840 | { | |
841 | } | |
8d8354d2 PE |
842 | #endif |
843 | ||
2c8c1e72 | 844 | static int __net_init ipv4_frags_init_net(struct net *net) |
8d8354d2 | 845 | { |
e31e0bdc PE |
846 | /* |
847 | * Fragment cache limits. We will commit 256K at one time. Should we | |
848 | * cross that limit we will prune down to 192K. This should cope with | |
849 | * even the most extreme cases without allowing an attacker to | |
850 | * measurably harm machine performance. | |
851 | */ | |
852 | net->ipv4.frags.high_thresh = 256 * 1024; | |
853 | net->ipv4.frags.low_thresh = 192 * 1024; | |
b2fd5321 PE |
854 | /* |
855 | * Important NOTE! Fragment queue must be destroyed before MSL expires. | |
856 | * RFC791 is wrong proposing to prolongate timer each fragment arrival | |
857 | * by TTL. | |
858 | */ | |
859 | net->ipv4.frags.timeout = IP_FRAG_TIME; | |
860 | ||
e5a2bb84 PE |
861 | inet_frags_init_net(&net->ipv4.frags); |
862 | ||
0a64b4b8 | 863 | return ip4_frags_ns_ctl_register(net); |
8d8354d2 PE |
864 | } |
865 | ||
2c8c1e72 | 866 | static void __net_exit ipv4_frags_exit_net(struct net *net) |
81566e83 | 867 | { |
0a64b4b8 | 868 | ip4_frags_ns_ctl_unregister(net); |
81566e83 PE |
869 | inet_frags_exit_net(&net->ipv4.frags, &ip4_frags); |
870 | } | |
871 | ||
872 | static struct pernet_operations ip4_frags_ops = { | |
873 | .init = ipv4_frags_init_net, | |
874 | .exit = ipv4_frags_exit_net, | |
875 | }; | |
876 | ||
b7aa0bf7 | 877 | void __init ipfrag_init(void) |
1da177e4 | 878 | { |
7d291ebb | 879 | ip4_frags_ctl_register(); |
81566e83 | 880 | register_pernet_subsys(&ip4_frags_ops); |
321a3a99 | 881 | ip4_frags.hashfn = ip4_hashfn; |
c6fda282 | 882 | ip4_frags.constructor = ip4_frag_init; |
1e4b8287 PE |
883 | ip4_frags.destructor = ip4_frag_free; |
884 | ip4_frags.skb_free = NULL; | |
885 | ip4_frags.qsize = sizeof(struct ipq); | |
abd6523d | 886 | ip4_frags.match = ip4_frag_match; |
e521db9d | 887 | ip4_frags.frag_expire = ip_expire; |
3b4bc4a2 | 888 | ip4_frags.secret_interval = 10 * 60 * HZ; |
7eb95156 | 889 | inet_frags_init(&ip4_frags); |
1da177e4 | 890 | } |