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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 | 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 | { |
d433673e | 125 | return sum_frag_mem_limit(&net->ipv4.frags); |
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 | ||
c6fda282 PE |
164 | static void ip4_frag_init(struct inet_frag_queue *q, void *a) |
165 | { | |
166 | struct ipq *qp = container_of(q, struct ipq, q); | |
54db0cc2 G |
167 | struct netns_ipv4 *ipv4 = container_of(q->net, struct netns_ipv4, |
168 | frags); | |
169 | struct net *net = container_of(ipv4, struct net, ipv4); | |
170 | ||
c6fda282 PE |
171 | struct ip4_create_arg *arg = a; |
172 | ||
173 | qp->protocol = arg->iph->protocol; | |
174 | qp->id = arg->iph->id; | |
6623e3b2 | 175 | qp->ecn = ip4_frag_ecn(arg->iph->tos); |
c6fda282 PE |
176 | qp->saddr = arg->iph->saddr; |
177 | qp->daddr = arg->iph->daddr; | |
178 | qp->user = arg->user; | |
179 | qp->peer = sysctl_ipfrag_max_dist ? | |
c0efc887 | 180 | inet_getpeer_v4(net->ipv4.peers, arg->iph->saddr, 1) : NULL; |
c6fda282 PE |
181 | } |
182 | ||
1e4b8287 | 183 | static __inline__ void ip4_frag_free(struct inet_frag_queue *q) |
1da177e4 | 184 | { |
1e4b8287 PE |
185 | struct ipq *qp; |
186 | ||
187 | qp = container_of(q, struct ipq, q); | |
188 | if (qp->peer) | |
189 | inet_putpeer(qp->peer); | |
1da177e4 LT |
190 | } |
191 | ||
1da177e4 LT |
192 | |
193 | /* Destruction primitives. */ | |
194 | ||
4b6cb5d8 | 195 | static __inline__ void ipq_put(struct ipq *ipq) |
1da177e4 | 196 | { |
762cc408 | 197 | inet_frag_put(&ipq->q, &ip4_frags); |
1da177e4 LT |
198 | } |
199 | ||
200 | /* Kill ipq entry. It is not destroyed immediately, | |
201 | * because caller (and someone more) holds reference count. | |
202 | */ | |
203 | static void ipq_kill(struct ipq *ipq) | |
204 | { | |
277e650d | 205 | inet_frag_kill(&ipq->q, &ip4_frags); |
1da177e4 LT |
206 | } |
207 | ||
e905a9ed | 208 | /* Memory limiting on fragments. Evictor trashes the oldest |
1da177e4 LT |
209 | * fragment queue until we are back under the threshold. |
210 | */ | |
6ddc0822 | 211 | static void ip_evictor(struct net *net) |
1da177e4 | 212 | { |
8e7999c4 PE |
213 | int evicted; |
214 | ||
6b102865 | 215 | evicted = inet_frag_evictor(&net->ipv4.frags, &ip4_frags, false); |
8e7999c4 | 216 | if (evicted) |
c5346fe3 | 217 | IP_ADD_STATS_BH(net, IPSTATS_MIB_REASMFAILS, evicted); |
1da177e4 LT |
218 | } |
219 | ||
220 | /* | |
221 | * Oops, a fragment queue timed out. Kill it and send an ICMP reply. | |
222 | */ | |
223 | static void ip_expire(unsigned long arg) | |
224 | { | |
e521db9d | 225 | struct ipq *qp; |
84a3aa00 | 226 | struct net *net; |
e521db9d PE |
227 | |
228 | qp = container_of((struct inet_frag_queue *) arg, struct ipq, q); | |
84a3aa00 | 229 | net = container_of(qp->q.net, struct net, ipv4.frags); |
1da177e4 | 230 | |
5ab11c98 | 231 | spin_lock(&qp->q.lock); |
1da177e4 | 232 | |
bc578a54 | 233 | if (qp->q.last_in & INET_FRAG_COMPLETE) |
1da177e4 LT |
234 | goto out; |
235 | ||
236 | ipq_kill(qp); | |
237 | ||
7c73a6fa PE |
238 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMTIMEOUT); |
239 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); | |
1da177e4 | 240 | |
bc578a54 | 241 | if ((qp->q.last_in & INET_FRAG_FIRST_IN) && qp->q.fragments != NULL) { |
5ab11c98 | 242 | struct sk_buff *head = qp->q.fragments; |
64f3b9e2 ED |
243 | const struct iphdr *iph; |
244 | int err; | |
cb84663e | 245 | |
69df9d59 ED |
246 | rcu_read_lock(); |
247 | head->dev = dev_get_by_index_rcu(net, qp->iif); | |
e9017b55 SW |
248 | if (!head->dev) |
249 | goto out_rcu_unlock; | |
250 | ||
64f3b9e2 ED |
251 | /* skb dst is stale, drop it, and perform route lookup again */ |
252 | skb_dst_drop(head); | |
253 | iph = ip_hdr(head); | |
c6cffba4 DM |
254 | err = ip_route_input_noref(head, iph->daddr, iph->saddr, |
255 | iph->tos, head->dev); | |
64f3b9e2 ED |
256 | if (err) |
257 | goto out_rcu_unlock; | |
258 | ||
e9017b55 | 259 | /* |
64f3b9e2 ED |
260 | * Only an end host needs to send an ICMP |
261 | * "Fragment Reassembly Timeout" message, per RFC792. | |
e9017b55 | 262 | */ |
595fc71b DM |
263 | if (qp->user == IP_DEFRAG_AF_PACKET || |
264 | (qp->user == IP_DEFRAG_CONNTRACK_IN && | |
265 | skb_rtable(head)->rt_type != RTN_LOCAL)) | |
64f3b9e2 ED |
266 | goto out_rcu_unlock; |
267 | ||
e9017b55 SW |
268 | |
269 | /* Send an ICMP "Fragment Reassembly Timeout" message. */ | |
270 | icmp_send(head, ICMP_TIME_EXCEEDED, ICMP_EXC_FRAGTIME, 0); | |
e9017b55 | 271 | out_rcu_unlock: |
d1c9ae6d PM |
272 | rcu_read_unlock(); |
273 | } | |
1da177e4 | 274 | out: |
5ab11c98 | 275 | spin_unlock(&qp->q.lock); |
4b6cb5d8 | 276 | ipq_put(qp); |
1da177e4 LT |
277 | } |
278 | ||
abd6523d PE |
279 | /* Find the correct entry in the "incomplete datagrams" queue for |
280 | * this IP datagram, and create new one, if nothing is found. | |
281 | */ | |
ac18e750 | 282 | static inline struct ipq *ip_find(struct net *net, struct iphdr *iph, u32 user) |
1da177e4 | 283 | { |
c6fda282 PE |
284 | struct inet_frag_queue *q; |
285 | struct ip4_create_arg arg; | |
abd6523d | 286 | unsigned int hash; |
1da177e4 | 287 | |
c6fda282 PE |
288 | arg.iph = iph; |
289 | arg.user = user; | |
9a375803 PE |
290 | |
291 | read_lock(&ip4_frags.lock); | |
abd6523d | 292 | hash = ipqhashfn(iph->id, iph->saddr, iph->daddr, iph->protocol); |
1da177e4 | 293 | |
ac18e750 | 294 | q = inet_frag_find(&net->ipv4.frags, &ip4_frags, &arg, hash); |
5a3da1fe HFS |
295 | if (IS_ERR_OR_NULL(q)) { |
296 | inet_frag_maybe_warn_overflow(q, pr_fmt()); | |
297 | return NULL; | |
298 | } | |
c6fda282 | 299 | return container_of(q, struct ipq, q); |
1da177e4 LT |
300 | } |
301 | ||
89cee8b1 HX |
302 | /* Is the fragment too far ahead to be part of ipq? */ |
303 | static inline int ip_frag_too_far(struct ipq *qp) | |
304 | { | |
305 | struct inet_peer *peer = qp->peer; | |
306 | unsigned int max = sysctl_ipfrag_max_dist; | |
307 | unsigned int start, end; | |
308 | ||
309 | int rc; | |
310 | ||
311 | if (!peer || !max) | |
312 | return 0; | |
313 | ||
314 | start = qp->rid; | |
315 | end = atomic_inc_return(&peer->rid); | |
316 | qp->rid = end; | |
317 | ||
5ab11c98 | 318 | rc = qp->q.fragments && (end - start) > max; |
89cee8b1 HX |
319 | |
320 | if (rc) { | |
7c73a6fa PE |
321 | struct net *net; |
322 | ||
323 | net = container_of(qp->q.net, struct net, ipv4.frags); | |
324 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); | |
89cee8b1 HX |
325 | } |
326 | ||
327 | return rc; | |
328 | } | |
329 | ||
330 | static int ip_frag_reinit(struct ipq *qp) | |
331 | { | |
332 | struct sk_buff *fp; | |
d433673e | 333 | unsigned int sum_truesize = 0; |
89cee8b1 | 334 | |
b2fd5321 | 335 | if (!mod_timer(&qp->q.timer, jiffies + qp->q.net->timeout)) { |
5ab11c98 | 336 | atomic_inc(&qp->q.refcnt); |
89cee8b1 HX |
337 | return -ETIMEDOUT; |
338 | } | |
339 | ||
5ab11c98 | 340 | fp = qp->q.fragments; |
89cee8b1 HX |
341 | do { |
342 | struct sk_buff *xp = fp->next; | |
d433673e JDB |
343 | |
344 | sum_truesize += fp->truesize; | |
345 | kfree_skb(fp); | |
89cee8b1 HX |
346 | fp = xp; |
347 | } while (fp); | |
d433673e | 348 | sub_frag_mem_limit(&qp->q, sum_truesize); |
89cee8b1 | 349 | |
5ab11c98 PE |
350 | qp->q.last_in = 0; |
351 | qp->q.len = 0; | |
352 | qp->q.meat = 0; | |
353 | qp->q.fragments = NULL; | |
d6bebca9 | 354 | qp->q.fragments_tail = NULL; |
89cee8b1 | 355 | qp->iif = 0; |
6623e3b2 | 356 | qp->ecn = 0; |
89cee8b1 HX |
357 | |
358 | return 0; | |
359 | } | |
360 | ||
1da177e4 | 361 | /* Add new segment to existing queue. */ |
1706d587 | 362 | static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) |
1da177e4 LT |
363 | { |
364 | struct sk_buff *prev, *next; | |
1706d587 | 365 | struct net_device *dev; |
1da177e4 LT |
366 | int flags, offset; |
367 | int ihl, end; | |
1706d587 | 368 | int err = -ENOENT; |
6623e3b2 | 369 | u8 ecn; |
1da177e4 | 370 | |
bc578a54 | 371 | if (qp->q.last_in & INET_FRAG_COMPLETE) |
1da177e4 LT |
372 | goto err; |
373 | ||
89cee8b1 | 374 | if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) && |
1706d587 HX |
375 | unlikely(ip_frag_too_far(qp)) && |
376 | unlikely(err = ip_frag_reinit(qp))) { | |
89cee8b1 HX |
377 | ipq_kill(qp); |
378 | goto err; | |
379 | } | |
380 | ||
6623e3b2 | 381 | ecn = ip4_frag_ecn(ip_hdr(skb)->tos); |
eddc9ec5 | 382 | offset = ntohs(ip_hdr(skb)->frag_off); |
1da177e4 LT |
383 | flags = offset & ~IP_OFFSET; |
384 | offset &= IP_OFFSET; | |
385 | offset <<= 3; /* offset is in 8-byte chunks */ | |
c9bdd4b5 | 386 | ihl = ip_hdrlen(skb); |
1da177e4 LT |
387 | |
388 | /* Determine the position of this fragment. */ | |
e905a9ed | 389 | end = offset + skb->len - ihl; |
1706d587 | 390 | err = -EINVAL; |
1da177e4 LT |
391 | |
392 | /* Is this the final fragment? */ | |
393 | if ((flags & IP_MF) == 0) { | |
394 | /* If we already have some bits beyond end | |
42b2aa86 | 395 | * or have different end, the segment is corrupted. |
1da177e4 | 396 | */ |
5ab11c98 | 397 | if (end < qp->q.len || |
bc578a54 | 398 | ((qp->q.last_in & INET_FRAG_LAST_IN) && end != qp->q.len)) |
1da177e4 | 399 | goto err; |
bc578a54 | 400 | qp->q.last_in |= INET_FRAG_LAST_IN; |
5ab11c98 | 401 | qp->q.len = end; |
1da177e4 LT |
402 | } else { |
403 | if (end&7) { | |
404 | end &= ~7; | |
405 | if (skb->ip_summed != CHECKSUM_UNNECESSARY) | |
406 | skb->ip_summed = CHECKSUM_NONE; | |
407 | } | |
5ab11c98 | 408 | if (end > qp->q.len) { |
1da177e4 | 409 | /* Some bits beyond end -> corruption. */ |
bc578a54 | 410 | if (qp->q.last_in & INET_FRAG_LAST_IN) |
1da177e4 | 411 | goto err; |
5ab11c98 | 412 | qp->q.len = end; |
1da177e4 LT |
413 | } |
414 | } | |
415 | if (end == offset) | |
416 | goto err; | |
417 | ||
1706d587 | 418 | err = -ENOMEM; |
1da177e4 LT |
419 | if (pskb_pull(skb, ihl) == NULL) |
420 | goto err; | |
1706d587 HX |
421 | |
422 | err = pskb_trim_rcsum(skb, end - offset); | |
423 | if (err) | |
1da177e4 LT |
424 | goto err; |
425 | ||
426 | /* Find out which fragments are in front and at the back of us | |
427 | * in the chain of fragments so far. We must know where to put | |
428 | * this fragment, right? | |
429 | */ | |
d6bebca9 CG |
430 | prev = qp->q.fragments_tail; |
431 | if (!prev || FRAG_CB(prev)->offset < offset) { | |
432 | next = NULL; | |
433 | goto found; | |
434 | } | |
1da177e4 | 435 | prev = NULL; |
5ab11c98 | 436 | for (next = qp->q.fragments; next != NULL; next = next->next) { |
1da177e4 LT |
437 | if (FRAG_CB(next)->offset >= offset) |
438 | break; /* bingo! */ | |
439 | prev = next; | |
440 | } | |
441 | ||
d6bebca9 | 442 | found: |
1da177e4 LT |
443 | /* We found where to put this one. Check for overlap with |
444 | * preceding fragment, and, if needed, align things so that | |
445 | * any overlaps are eliminated. | |
446 | */ | |
447 | if (prev) { | |
448 | int i = (FRAG_CB(prev)->offset + prev->len) - offset; | |
449 | ||
450 | if (i > 0) { | |
451 | offset += i; | |
1706d587 | 452 | err = -EINVAL; |
1da177e4 LT |
453 | if (end <= offset) |
454 | goto err; | |
1706d587 | 455 | err = -ENOMEM; |
1da177e4 LT |
456 | if (!pskb_pull(skb, i)) |
457 | goto err; | |
458 | if (skb->ip_summed != CHECKSUM_UNNECESSARY) | |
459 | skb->ip_summed = CHECKSUM_NONE; | |
460 | } | |
461 | } | |
462 | ||
1706d587 HX |
463 | err = -ENOMEM; |
464 | ||
1da177e4 LT |
465 | while (next && FRAG_CB(next)->offset < end) { |
466 | int i = end - FRAG_CB(next)->offset; /* overlap is 'i' bytes */ | |
467 | ||
468 | if (i < next->len) { | |
469 | /* Eat head of the next overlapped fragment | |
470 | * and leave the loop. The next ones cannot overlap. | |
471 | */ | |
472 | if (!pskb_pull(next, i)) | |
473 | goto err; | |
474 | FRAG_CB(next)->offset += i; | |
5ab11c98 | 475 | qp->q.meat -= i; |
1da177e4 LT |
476 | if (next->ip_summed != CHECKSUM_UNNECESSARY) |
477 | next->ip_summed = CHECKSUM_NONE; | |
478 | break; | |
479 | } else { | |
480 | struct sk_buff *free_it = next; | |
481 | ||
47c6bf77 | 482 | /* Old fragment is completely overridden with |
1da177e4 LT |
483 | * new one drop it. |
484 | */ | |
485 | next = next->next; | |
486 | ||
487 | if (prev) | |
488 | prev->next = next; | |
489 | else | |
5ab11c98 | 490 | qp->q.fragments = next; |
1da177e4 | 491 | |
5ab11c98 | 492 | qp->q.meat -= free_it->len; |
d433673e JDB |
493 | sub_frag_mem_limit(&qp->q, free_it->truesize); |
494 | kfree_skb(free_it); | |
1da177e4 LT |
495 | } |
496 | } | |
497 | ||
498 | FRAG_CB(skb)->offset = offset; | |
499 | ||
500 | /* Insert this fragment in the chain of fragments. */ | |
501 | skb->next = next; | |
d6bebca9 CG |
502 | if (!next) |
503 | qp->q.fragments_tail = skb; | |
1da177e4 LT |
504 | if (prev) |
505 | prev->next = skb; | |
506 | else | |
5ab11c98 | 507 | qp->q.fragments = skb; |
1da177e4 | 508 | |
1706d587 HX |
509 | dev = skb->dev; |
510 | if (dev) { | |
511 | qp->iif = dev->ifindex; | |
512 | skb->dev = NULL; | |
513 | } | |
5ab11c98 PE |
514 | qp->q.stamp = skb->tstamp; |
515 | qp->q.meat += skb->len; | |
6623e3b2 | 516 | qp->ecn |= ecn; |
d433673e | 517 | add_frag_mem_limit(&qp->q, skb->truesize); |
1da177e4 | 518 | if (offset == 0) |
bc578a54 | 519 | qp->q.last_in |= INET_FRAG_FIRST_IN; |
1da177e4 | 520 | |
5f2d04f1 PM |
521 | if (ip_hdr(skb)->frag_off & htons(IP_DF) && |
522 | skb->len + ihl > qp->q.max_size) | |
523 | qp->q.max_size = skb->len + ihl; | |
524 | ||
bc578a54 JP |
525 | if (qp->q.last_in == (INET_FRAG_FIRST_IN | INET_FRAG_LAST_IN) && |
526 | qp->q.meat == qp->q.len) | |
1706d587 HX |
527 | return ip_frag_reasm(qp, prev, dev); |
528 | ||
3ef0eb0d | 529 | inet_frag_lru_move(&qp->q); |
1706d587 | 530 | return -EINPROGRESS; |
1da177e4 LT |
531 | |
532 | err: | |
533 | kfree_skb(skb); | |
1706d587 | 534 | return err; |
1da177e4 LT |
535 | } |
536 | ||
537 | ||
538 | /* Build a new IP datagram from all its fragments. */ | |
539 | ||
1706d587 HX |
540 | static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev, |
541 | struct net_device *dev) | |
1da177e4 | 542 | { |
2bad35b7 | 543 | struct net *net = container_of(qp->q.net, struct net, ipv4.frags); |
1da177e4 | 544 | struct iphdr *iph; |
5ab11c98 | 545 | struct sk_buff *fp, *head = qp->q.fragments; |
1da177e4 LT |
546 | int len; |
547 | int ihlen; | |
1706d587 | 548 | int err; |
3cc49492 | 549 | int sum_truesize; |
5173cc05 | 550 | u8 ecn; |
1da177e4 LT |
551 | |
552 | ipq_kill(qp); | |
553 | ||
5173cc05 ED |
554 | ecn = ip4_frag_ecn_table[qp->ecn]; |
555 | if (unlikely(ecn == 0xff)) { | |
556 | err = -EINVAL; | |
557 | goto out_fail; | |
558 | } | |
1706d587 HX |
559 | /* Make the one we just received the head. */ |
560 | if (prev) { | |
561 | head = prev->next; | |
562 | fp = skb_clone(head, GFP_ATOMIC); | |
1706d587 HX |
563 | if (!fp) |
564 | goto out_nomem; | |
565 | ||
566 | fp->next = head->next; | |
d6bebca9 CG |
567 | if (!fp->next) |
568 | qp->q.fragments_tail = fp; | |
1706d587 HX |
569 | prev->next = fp; |
570 | ||
5ab11c98 PE |
571 | skb_morph(head, qp->q.fragments); |
572 | head->next = qp->q.fragments->next; | |
1706d587 | 573 | |
cbf8f7bb | 574 | consume_skb(qp->q.fragments); |
5ab11c98 | 575 | qp->q.fragments = head; |
1706d587 HX |
576 | } |
577 | ||
547b792c IJ |
578 | WARN_ON(head == NULL); |
579 | WARN_ON(FRAG_CB(head)->offset != 0); | |
1da177e4 LT |
580 | |
581 | /* Allocate a new buffer for the datagram. */ | |
c9bdd4b5 | 582 | ihlen = ip_hdrlen(head); |
5ab11c98 | 583 | len = ihlen + qp->q.len; |
1da177e4 | 584 | |
1706d587 | 585 | err = -E2BIG; |
132adf54 | 586 | if (len > 65535) |
1da177e4 LT |
587 | goto out_oversize; |
588 | ||
589 | /* Head of list must not be cloned. */ | |
14bbd6a5 | 590 | if (skb_unclone(head, GFP_ATOMIC)) |
1da177e4 LT |
591 | goto out_nomem; |
592 | ||
593 | /* If the first fragment is fragmented itself, we split | |
594 | * it to two chunks: the first with data and paged part | |
595 | * and the second, holding only fragments. */ | |
21dc3301 | 596 | if (skb_has_frag_list(head)) { |
1da177e4 LT |
597 | struct sk_buff *clone; |
598 | int i, plen = 0; | |
599 | ||
600 | if ((clone = alloc_skb(0, GFP_ATOMIC)) == NULL) | |
601 | goto out_nomem; | |
602 | clone->next = head->next; | |
603 | head->next = clone; | |
604 | skb_shinfo(clone)->frag_list = skb_shinfo(head)->frag_list; | |
d7fcf1a5 | 605 | skb_frag_list_init(head); |
9e903e08 ED |
606 | for (i = 0; i < skb_shinfo(head)->nr_frags; i++) |
607 | plen += skb_frag_size(&skb_shinfo(head)->frags[i]); | |
1da177e4 LT |
608 | clone->len = clone->data_len = head->data_len - plen; |
609 | head->data_len -= clone->len; | |
610 | head->len -= clone->len; | |
611 | clone->csum = 0; | |
612 | clone->ip_summed = head->ip_summed; | |
d433673e | 613 | add_frag_mem_limit(&qp->q, clone->truesize); |
1da177e4 LT |
614 | } |
615 | ||
d56f90a7 | 616 | skb_push(head, head->data - skb_network_header(head)); |
1da177e4 | 617 | |
3cc49492 ED |
618 | sum_truesize = head->truesize; |
619 | for (fp = head->next; fp;) { | |
620 | bool headstolen; | |
621 | int delta; | |
622 | struct sk_buff *next = fp->next; | |
623 | ||
624 | sum_truesize += fp->truesize; | |
1da177e4 LT |
625 | if (head->ip_summed != fp->ip_summed) |
626 | head->ip_summed = CHECKSUM_NONE; | |
84fa7933 | 627 | else if (head->ip_summed == CHECKSUM_COMPLETE) |
1da177e4 | 628 | head->csum = csum_add(head->csum, fp->csum); |
3cc49492 ED |
629 | |
630 | if (skb_try_coalesce(head, fp, &headstolen, &delta)) { | |
631 | kfree_skb_partial(fp, headstolen); | |
632 | } else { | |
633 | if (!skb_shinfo(head)->frag_list) | |
634 | skb_shinfo(head)->frag_list = fp; | |
635 | head->data_len += fp->len; | |
636 | head->len += fp->len; | |
637 | head->truesize += fp->truesize; | |
638 | } | |
639 | fp = next; | |
1da177e4 | 640 | } |
d433673e | 641 | sub_frag_mem_limit(&qp->q, sum_truesize); |
1da177e4 LT |
642 | |
643 | head->next = NULL; | |
644 | head->dev = dev; | |
5ab11c98 | 645 | head->tstamp = qp->q.stamp; |
5f2d04f1 | 646 | IPCB(head)->frag_max_size = qp->q.max_size; |
1da177e4 | 647 | |
eddc9ec5 | 648 | iph = ip_hdr(head); |
5f2d04f1 PM |
649 | /* max_size != 0 implies at least one fragment had IP_DF set */ |
650 | iph->frag_off = qp->q.max_size ? htons(IP_DF) : 0; | |
1da177e4 | 651 | iph->tot_len = htons(len); |
5173cc05 | 652 | iph->tos |= ecn; |
2bad35b7 | 653 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMOKS); |
5ab11c98 | 654 | qp->q.fragments = NULL; |
d6bebca9 | 655 | qp->q.fragments_tail = NULL; |
1706d587 | 656 | return 0; |
1da177e4 LT |
657 | |
658 | out_nomem: | |
afd46503 JP |
659 | LIMIT_NETDEBUG(KERN_ERR pr_fmt("queue_glue: no memory for gluing queue %p\n"), |
660 | qp); | |
45542479 | 661 | err = -ENOMEM; |
1da177e4 LT |
662 | goto out_fail; |
663 | out_oversize: | |
e87cc472 | 664 | net_info_ratelimited("Oversized IP packet from %pI4\n", &qp->saddr); |
1da177e4 | 665 | out_fail: |
bbf31bf1 | 666 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); |
1706d587 | 667 | return err; |
1da177e4 LT |
668 | } |
669 | ||
670 | /* Process an incoming IP datagram fragment. */ | |
776c729e | 671 | int ip_defrag(struct sk_buff *skb, u32 user) |
1da177e4 | 672 | { |
1da177e4 | 673 | struct ipq *qp; |
ac18e750 | 674 | struct net *net; |
e905a9ed | 675 | |
adf30907 | 676 | net = skb->dev ? dev_net(skb->dev) : dev_net(skb_dst(skb)->dev); |
7c73a6fa | 677 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMREQDS); |
1da177e4 LT |
678 | |
679 | /* Start by cleaning up the memory. */ | |
6b102865 | 680 | ip_evictor(net); |
1da177e4 | 681 | |
1da177e4 | 682 | /* Lookup (or create) queue header */ |
ac18e750 | 683 | if ((qp = ip_find(net, ip_hdr(skb), user)) != NULL) { |
1706d587 | 684 | int ret; |
1da177e4 | 685 | |
5ab11c98 | 686 | spin_lock(&qp->q.lock); |
1da177e4 | 687 | |
1706d587 | 688 | ret = ip_frag_queue(qp, skb); |
1da177e4 | 689 | |
5ab11c98 | 690 | spin_unlock(&qp->q.lock); |
4b6cb5d8 | 691 | ipq_put(qp); |
776c729e | 692 | return ret; |
1da177e4 LT |
693 | } |
694 | ||
7c73a6fa | 695 | IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS); |
1da177e4 | 696 | kfree_skb(skb); |
776c729e | 697 | return -ENOMEM; |
1da177e4 | 698 | } |
4bc2f18b | 699 | EXPORT_SYMBOL(ip_defrag); |
1da177e4 | 700 | |
bc416d97 ED |
701 | struct sk_buff *ip_check_defrag(struct sk_buff *skb, u32 user) |
702 | { | |
1bf3751e | 703 | struct iphdr iph; |
bc416d97 ED |
704 | u32 len; |
705 | ||
706 | if (skb->protocol != htons(ETH_P_IP)) | |
707 | return skb; | |
708 | ||
1bf3751e | 709 | if (!skb_copy_bits(skb, 0, &iph, sizeof(iph))) |
bc416d97 ED |
710 | return skb; |
711 | ||
1bf3751e | 712 | if (iph.ihl < 5 || iph.version != 4) |
bc416d97 | 713 | return skb; |
1bf3751e JB |
714 | |
715 | len = ntohs(iph.tot_len); | |
716 | if (skb->len < len || len < (iph.ihl * 4)) | |
bc416d97 ED |
717 | return skb; |
718 | ||
1bf3751e | 719 | if (ip_is_fragment(&iph)) { |
bc416d97 ED |
720 | skb = skb_share_check(skb, GFP_ATOMIC); |
721 | if (skb) { | |
1bf3751e JB |
722 | if (!pskb_may_pull(skb, iph.ihl*4)) |
723 | return skb; | |
bc416d97 ED |
724 | if (pskb_trim_rcsum(skb, len)) |
725 | return skb; | |
726 | memset(IPCB(skb), 0, sizeof(struct inet_skb_parm)); | |
727 | if (ip_defrag(skb, user)) | |
728 | return NULL; | |
729 | skb->rxhash = 0; | |
730 | } | |
731 | } | |
732 | return skb; | |
733 | } | |
734 | EXPORT_SYMBOL(ip_check_defrag); | |
735 | ||
8d8354d2 PE |
736 | #ifdef CONFIG_SYSCTL |
737 | static int zero; | |
738 | ||
0a64b4b8 | 739 | static struct ctl_table ip4_frags_ns_ctl_table[] = { |
8d8354d2 | 740 | { |
8d8354d2 | 741 | .procname = "ipfrag_high_thresh", |
e31e0bdc | 742 | .data = &init_net.ipv4.frags.high_thresh, |
8d8354d2 PE |
743 | .maxlen = sizeof(int), |
744 | .mode = 0644, | |
6d9f239a | 745 | .proc_handler = proc_dointvec |
8d8354d2 PE |
746 | }, |
747 | { | |
8d8354d2 | 748 | .procname = "ipfrag_low_thresh", |
e31e0bdc | 749 | .data = &init_net.ipv4.frags.low_thresh, |
8d8354d2 PE |
750 | .maxlen = sizeof(int), |
751 | .mode = 0644, | |
6d9f239a | 752 | .proc_handler = proc_dointvec |
8d8354d2 PE |
753 | }, |
754 | { | |
8d8354d2 | 755 | .procname = "ipfrag_time", |
b2fd5321 | 756 | .data = &init_net.ipv4.frags.timeout, |
8d8354d2 PE |
757 | .maxlen = sizeof(int), |
758 | .mode = 0644, | |
6d9f239a | 759 | .proc_handler = proc_dointvec_jiffies, |
8d8354d2 | 760 | }, |
7d291ebb PE |
761 | { } |
762 | }; | |
763 | ||
764 | static struct ctl_table ip4_frags_ctl_table[] = { | |
8d8354d2 | 765 | { |
8d8354d2 | 766 | .procname = "ipfrag_secret_interval", |
3b4bc4a2 | 767 | .data = &ip4_frags.secret_interval, |
8d8354d2 PE |
768 | .maxlen = sizeof(int), |
769 | .mode = 0644, | |
6d9f239a | 770 | .proc_handler = proc_dointvec_jiffies, |
8d8354d2 PE |
771 | }, |
772 | { | |
773 | .procname = "ipfrag_max_dist", | |
774 | .data = &sysctl_ipfrag_max_dist, | |
775 | .maxlen = sizeof(int), | |
776 | .mode = 0644, | |
6d9f239a | 777 | .proc_handler = proc_dointvec_minmax, |
8d8354d2 PE |
778 | .extra1 = &zero |
779 | }, | |
780 | { } | |
781 | }; | |
782 | ||
2c8c1e72 | 783 | static int __net_init ip4_frags_ns_ctl_register(struct net *net) |
8d8354d2 | 784 | { |
e4a2d5c2 | 785 | struct ctl_table *table; |
8d8354d2 PE |
786 | struct ctl_table_header *hdr; |
787 | ||
0a64b4b8 | 788 | table = ip4_frags_ns_ctl_table; |
09ad9bc7 | 789 | if (!net_eq(net, &init_net)) { |
0a64b4b8 | 790 | table = kmemdup(table, sizeof(ip4_frags_ns_ctl_table), GFP_KERNEL); |
e4a2d5c2 PE |
791 | if (table == NULL) |
792 | goto err_alloc; | |
793 | ||
e31e0bdc PE |
794 | table[0].data = &net->ipv4.frags.high_thresh; |
795 | table[1].data = &net->ipv4.frags.low_thresh; | |
b2fd5321 | 796 | table[2].data = &net->ipv4.frags.timeout; |
464dc801 EB |
797 | |
798 | /* Don't export sysctls to unprivileged users */ | |
799 | if (net->user_ns != &init_user_ns) | |
800 | table[0].procname = NULL; | |
e4a2d5c2 PE |
801 | } |
802 | ||
ec8f23ce | 803 | hdr = register_net_sysctl(net, "net/ipv4", table); |
e4a2d5c2 PE |
804 | if (hdr == NULL) |
805 | goto err_reg; | |
806 | ||
807 | net->ipv4.frags_hdr = hdr; | |
808 | return 0; | |
809 | ||
810 | err_reg: | |
09ad9bc7 | 811 | if (!net_eq(net, &init_net)) |
e4a2d5c2 PE |
812 | kfree(table); |
813 | err_alloc: | |
814 | return -ENOMEM; | |
815 | } | |
816 | ||
2c8c1e72 | 817 | static void __net_exit ip4_frags_ns_ctl_unregister(struct net *net) |
e4a2d5c2 PE |
818 | { |
819 | struct ctl_table *table; | |
820 | ||
821 | table = net->ipv4.frags_hdr->ctl_table_arg; | |
822 | unregister_net_sysctl_table(net->ipv4.frags_hdr); | |
823 | kfree(table); | |
8d8354d2 | 824 | } |
7d291ebb PE |
825 | |
826 | static void ip4_frags_ctl_register(void) | |
827 | { | |
43444757 | 828 | register_net_sysctl(&init_net, "net/ipv4", ip4_frags_ctl_table); |
7d291ebb | 829 | } |
8d8354d2 | 830 | #else |
0a64b4b8 | 831 | static inline int ip4_frags_ns_ctl_register(struct net *net) |
8d8354d2 PE |
832 | { |
833 | return 0; | |
834 | } | |
e4a2d5c2 | 835 | |
0a64b4b8 | 836 | static inline void ip4_frags_ns_ctl_unregister(struct net *net) |
e4a2d5c2 PE |
837 | { |
838 | } | |
7d291ebb PE |
839 | |
840 | static inline void ip4_frags_ctl_register(void) | |
841 | { | |
842 | } | |
8d8354d2 PE |
843 | #endif |
844 | ||
2c8c1e72 | 845 | static int __net_init ipv4_frags_init_net(struct net *net) |
8d8354d2 | 846 | { |
c2a93660 JDB |
847 | /* Fragment cache limits. |
848 | * | |
849 | * The fragment memory accounting code, (tries to) account for | |
850 | * the real memory usage, by measuring both the size of frag | |
851 | * queue struct (inet_frag_queue (ipv4:ipq/ipv6:frag_queue)) | |
852 | * and the SKB's truesize. | |
853 | * | |
854 | * A 64K fragment consumes 129736 bytes (44*2944)+200 | |
855 | * (1500 truesize == 2944, sizeof(struct ipq) == 200) | |
856 | * | |
857 | * We will commit 4MB at one time. Should we cross that limit | |
858 | * we will prune down to 3MB, making room for approx 8 big 64K | |
859 | * fragments 8x128k. | |
e31e0bdc | 860 | */ |
c2a93660 JDB |
861 | net->ipv4.frags.high_thresh = 4 * 1024 * 1024; |
862 | net->ipv4.frags.low_thresh = 3 * 1024 * 1024; | |
b2fd5321 PE |
863 | /* |
864 | * Important NOTE! Fragment queue must be destroyed before MSL expires. | |
865 | * RFC791 is wrong proposing to prolongate timer each fragment arrival | |
866 | * by TTL. | |
867 | */ | |
868 | net->ipv4.frags.timeout = IP_FRAG_TIME; | |
869 | ||
e5a2bb84 PE |
870 | inet_frags_init_net(&net->ipv4.frags); |
871 | ||
0a64b4b8 | 872 | return ip4_frags_ns_ctl_register(net); |
8d8354d2 PE |
873 | } |
874 | ||
2c8c1e72 | 875 | static void __net_exit ipv4_frags_exit_net(struct net *net) |
81566e83 | 876 | { |
0a64b4b8 | 877 | ip4_frags_ns_ctl_unregister(net); |
81566e83 PE |
878 | inet_frags_exit_net(&net->ipv4.frags, &ip4_frags); |
879 | } | |
880 | ||
881 | static struct pernet_operations ip4_frags_ops = { | |
882 | .init = ipv4_frags_init_net, | |
883 | .exit = ipv4_frags_exit_net, | |
884 | }; | |
885 | ||
b7aa0bf7 | 886 | void __init ipfrag_init(void) |
1da177e4 | 887 | { |
7d291ebb | 888 | ip4_frags_ctl_register(); |
81566e83 | 889 | register_pernet_subsys(&ip4_frags_ops); |
321a3a99 | 890 | ip4_frags.hashfn = ip4_hashfn; |
c6fda282 | 891 | ip4_frags.constructor = ip4_frag_init; |
1e4b8287 PE |
892 | ip4_frags.destructor = ip4_frag_free; |
893 | ip4_frags.skb_free = NULL; | |
894 | ip4_frags.qsize = sizeof(struct ipq); | |
abd6523d | 895 | ip4_frags.match = ip4_frag_match; |
e521db9d | 896 | ip4_frags.frag_expire = ip_expire; |
3b4bc4a2 | 897 | ip4_frags.secret_interval = 10 * 60 * HZ; |
7eb95156 | 898 | inet_frags_init(&ip4_frags); |
1da177e4 | 899 | } |