projects/linux·blob v4.14 · refs

569 lines · 13.3 KiB

1/*
2 * Stream Parser
3 *
4 * Copyright (c) 2016 Tom Herbert <[email protected]>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2
8 * as published by the Free Software Foundation.
9 */
10
11#include <linux/bpf.h>
12#include <linux/errno.h>
13#include <linux/errqueue.h>
14#include <linux/file.h>
15#include <linux/in.h>
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/net.h>
19#include <linux/netdevice.h>
20#include <linux/poll.h>
21#include <linux/rculist.h>
22#include <linux/skbuff.h>
23#include <linux/socket.h>
24#include <linux/uaccess.h>
25#include <linux/workqueue.h>
26#include <net/strparser.h>
27#include <net/netns/generic.h>
28#include <net/sock.h>
29
30static struct workqueue_struct *strp_wq;
31
32struct _strp_msg {
33 /* Internal cb structure. struct strp_msg must be first for passing
34 * to upper layer.
35 */
36 struct strp_msg strp;
37 int accum_len;
38 int early_eaten;
39};
40
41static inline struct _strp_msg *_strp_msg(struct sk_buff *skb)
42{
43 return (struct _strp_msg *)((void *)skb->cb +
44 offsetof(struct qdisc_skb_cb, data));
45}
46
47/* Lower lock held */
48static void strp_abort_strp(struct strparser *strp, int err)
49{
50 /* Unrecoverable error in receive */
51
52 cancel_delayed_work(&strp->msg_timer_work);
53
54 if (strp->stopped)
55 return;
56
57 strp->stopped = 1;
58
59 if (strp->sk) {
60 struct sock *sk = strp->sk;
61
62 /* Report an error on the lower socket */
63 sk->sk_err = err;
64 sk->sk_error_report(sk);
65 }
66}
67
68static void strp_start_timer(struct strparser *strp, long timeo)
69{
70 if (timeo)
71 mod_delayed_work(strp_wq, &strp->msg_timer_work, timeo);
72}
73
74/* Lower lock held */
75static void strp_parser_err(struct strparser *strp, int err,
76 read_descriptor_t *desc)
77{
78 desc->error = err;
79 kfree_skb(strp->skb_head);
80 strp->skb_head = NULL;
81 strp->cb.abort_parser(strp, err);
82}
83
84static inline int strp_peek_len(struct strparser *strp)
85{
86 if (strp->sk) {
87 struct socket *sock = strp->sk->sk_socket;
88
89 return sock->ops->peek_len(sock);
90 }
91
92 /* If we don't have an associated socket there's nothing to peek.
93 * Return int max to avoid stopping the strparser.
94 */
95
96 return INT_MAX;
97}
98
99/* Lower socket lock held */
100static int __strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
101 unsigned int orig_offset, size_t orig_len,
102 size_t max_msg_size, long timeo)
103{
104 struct strparser *strp = (struct strparser *)desc->arg.data;
105 struct _strp_msg *stm;
106 struct sk_buff *head, *skb;
107 size_t eaten = 0, cand_len;
108 ssize_t extra;
109 int err;
110 bool cloned_orig = false;
111
112 if (strp->paused)
113 return 0;
114
115 head = strp->skb_head;
116 if (head) {
117 /* Message already in progress */
118
119 stm = _strp_msg(head);
120 if (unlikely(stm->early_eaten)) {
121 /* Already some number of bytes on the receive sock
122 * data saved in skb_head, just indicate they
123 * are consumed.
124 */
125 eaten = orig_len <= stm->early_eaten ?
126 orig_len : stm->early_eaten;
127 stm->early_eaten -= eaten;
128
129 return eaten;
130 }
131
132 if (unlikely(orig_offset)) {
133 /* Getting data with a non-zero offset when a message is
134 * in progress is not expected. If it does happen, we
135 * need to clone and pull since we can't deal with
136 * offsets in the skbs for a message expect in the head.
137 */
138 orig_skb = skb_clone(orig_skb, GFP_ATOMIC);
139 if (!orig_skb) {
140 STRP_STATS_INCR(strp->stats.mem_fail);
141 desc->error = -ENOMEM;
142 return 0;
143 }
144 if (!pskb_pull(orig_skb, orig_offset)) {
145 STRP_STATS_INCR(strp->stats.mem_fail);
146 kfree_skb(orig_skb);
147 desc->error = -ENOMEM;
148 return 0;
149 }
150 cloned_orig = true;
151 orig_offset = 0;
152 }
153
154 if (!strp->skb_nextp) {
155 /* We are going to append to the frags_list of head.
156 * Need to unshare the frag_list.
157 */
158 err = skb_unclone(head, GFP_ATOMIC);
159 if (err) {
160 STRP_STATS_INCR(strp->stats.mem_fail);
161 desc->error = err;
162 return 0;
163 }
164
165 if (unlikely(skb_shinfo(head)->frag_list)) {
166 /* We can't append to an sk_buff that already
167 * has a frag_list. We create a new head, point
168 * the frag_list of that to the old head, and
169 * then are able to use the old head->next for
170 * appending to the message.
171 */
172 if (WARN_ON(head->next)) {
173 desc->error = -EINVAL;
174 return 0;
175 }
176
177 skb = alloc_skb(0, GFP_ATOMIC);
178 if (!skb) {
179 STRP_STATS_INCR(strp->stats.mem_fail);
180 desc->error = -ENOMEM;
181 return 0;
182 }
183 skb->len = head->len;
184 skb->data_len = head->len;
185 skb->truesize = head->truesize;
186 *_strp_msg(skb) = *_strp_msg(head);
187 strp->skb_nextp = &head->next;
188 skb_shinfo(skb)->frag_list = head;
189 strp->skb_head = skb;
190 head = skb;
191 } else {
192 strp->skb_nextp =
193 &skb_shinfo(head)->frag_list;
194 }
195 }
196 }
197
198 while (eaten < orig_len) {
199 /* Always clone since we will consume something */
200 skb = skb_clone(orig_skb, GFP_ATOMIC);
201 if (!skb) {
202 STRP_STATS_INCR(strp->stats.mem_fail);
203 desc->error = -ENOMEM;
204 break;
205 }
206
207 cand_len = orig_len - eaten;
208
209 head = strp->skb_head;
210 if (!head) {
211 head = skb;
212 strp->skb_head = head;
213 /* Will set skb_nextp on next packet if needed */
214 strp->skb_nextp = NULL;
215 stm = _strp_msg(head);
216 memset(stm, 0, sizeof(*stm));
217 stm->strp.offset = orig_offset + eaten;
218 } else {
219 /* Unclone since we may be appending to an skb that we
220 * already share a frag_list with.
221 */
222 err = skb_unclone(skb, GFP_ATOMIC);
223 if (err) {
224 STRP_STATS_INCR(strp->stats.mem_fail);
225 desc->error = err;
226 break;
227 }
228
229 stm = _strp_msg(head);
230 *strp->skb_nextp = skb;
231 strp->skb_nextp = &skb->next;
232 head->data_len += skb->len;
233 head->len += skb->len;
234 head->truesize += skb->truesize;
235 }
236
237 if (!stm->strp.full_len) {
238 ssize_t len;
239
240 len = (*strp->cb.parse_msg)(strp, head);
241
242 if (!len) {
243 /* Need more header to determine length */
244 if (!stm->accum_len) {
245 /* Start RX timer for new message */
246 strp_start_timer(strp, timeo);
247 }
248 stm->accum_len += cand_len;
249 eaten += cand_len;
250 STRP_STATS_INCR(strp->stats.need_more_hdr);
251 WARN_ON(eaten != orig_len);
252 break;
253 } else if (len < 0) {
254 if (len == -ESTRPIPE && stm->accum_len) {
255 len = -ENODATA;
256 strp->unrecov_intr = 1;
257 } else {
258 strp->interrupted = 1;
259 }
260 strp_parser_err(strp, len, desc);
261 break;
262 } else if (len > max_msg_size) {
263 /* Message length exceeds maximum allowed */
264 STRP_STATS_INCR(strp->stats.msg_too_big);
265 strp_parser_err(strp, -EMSGSIZE, desc);
266 break;
267 } else if (len <= (ssize_t)head->len -
268 skb->len - stm->strp.offset) {
269 /* Length must be into new skb (and also
270 * greater than zero)
271 */
272 STRP_STATS_INCR(strp->stats.bad_hdr_len);
273 strp_parser_err(strp, -EPROTO, desc);
274 break;
275 }
276
277 stm->strp.full_len = len;
278 }
279
280 extra = (ssize_t)(stm->accum_len + cand_len) -
281 stm->strp.full_len;
282
283 if (extra < 0) {
284 /* Message not complete yet. */
285 if (stm->strp.full_len - stm->accum_len >
286 strp_peek_len(strp)) {
287 /* Don't have the whole message in the socket
288 * buffer. Set strp->need_bytes to wait for
289 * the rest of the message. Also, set "early
290 * eaten" since we've already buffered the skb
291 * but don't consume yet per strp_read_sock.
292 */
293
294 if (!stm->accum_len) {
295 /* Start RX timer for new message */
296 strp_start_timer(strp, timeo);
297 }
298
299 strp->need_bytes = stm->strp.full_len -
300 stm->accum_len;
301 stm->accum_len += cand_len;
302 stm->early_eaten = cand_len;
303 STRP_STATS_ADD(strp->stats.bytes, cand_len);
304 desc->count = 0; /* Stop reading socket */
305 break;
306 }
307 stm->accum_len += cand_len;
308 eaten += cand_len;
309 WARN_ON(eaten != orig_len);
310 break;
311 }
312
313 /* Positive extra indicates ore bytes than needed for the
314 * message
315 */
316
317 WARN_ON(extra > cand_len);
318
319 eaten += (cand_len - extra);
320
321 /* Hurray, we have a new message! */
322 cancel_delayed_work(&strp->msg_timer_work);
323 strp->skb_head = NULL;
324 STRP_STATS_INCR(strp->stats.msgs);
325
326 /* Give skb to upper layer */
327 strp->cb.rcv_msg(strp, head);
328
329 if (unlikely(strp->paused)) {
330 /* Upper layer paused strp */
331 break;
332 }
333 }
334
335 if (cloned_orig)
336 kfree_skb(orig_skb);
337
338 STRP_STATS_ADD(strp->stats.bytes, eaten);
339
340 return eaten;
341}
342
343int strp_process(struct strparser *strp, struct sk_buff *orig_skb,
344 unsigned int orig_offset, size_t orig_len,
345 size_t max_msg_size, long timeo)
346{
347 read_descriptor_t desc; /* Dummy arg to strp_recv */
348
349 desc.arg.data = strp;
350
351 return __strp_recv(&desc, orig_skb, orig_offset, orig_len,
352 max_msg_size, timeo);
353}
354EXPORT_SYMBOL_GPL(strp_process);
355
356static int strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
357 unsigned int orig_offset, size_t orig_len)
358{
359 struct strparser *strp = (struct strparser *)desc->arg.data;
360
361 return __strp_recv(desc, orig_skb, orig_offset, orig_len,
362 strp->sk->sk_rcvbuf, strp->sk->sk_rcvtimeo);
363}
364
365static int default_read_sock_done(struct strparser *strp, int err)
366{
367 return err;
368}
369
370/* Called with lock held on lower socket */
371static int strp_read_sock(struct strparser *strp)
372{
373 struct socket *sock = strp->sk->sk_socket;
374 read_descriptor_t desc;
375
376 if (unlikely(!sock || !sock->ops || !sock->ops->read_sock))
377 return -EBUSY;
378
379 desc.arg.data = strp;
380 desc.error = 0;
381 desc.count = 1; /* give more than one skb per call */
382
383 /* sk should be locked here, so okay to do read_sock */
384 sock->ops->read_sock(strp->sk, &desc, strp_recv);
385
386 desc.error = strp->cb.read_sock_done(strp, desc.error);
387
388 return desc.error;
389}
390
391/* Lower sock lock held */
392void strp_data_ready(struct strparser *strp)
393{
394 if (unlikely(strp->stopped))
395 return;
396
397 /* This check is needed to synchronize with do_strp_work.
398 * do_strp_work acquires a process lock (lock_sock) whereas
399 * the lock held here is bh_lock_sock. The two locks can be
400 * held by different threads at the same time, but bh_lock_sock
401 * allows a thread in BH context to safely check if the process
402 * lock is held. In this case, if the lock is held, queue work.
403 */
404 if (sock_owned_by_user(strp->sk)) {
405 queue_work(strp_wq, &strp->work);
406 return;
407 }
408
409 if (strp->paused)
410 return;
411
412 if (strp->need_bytes) {
413 if (strp_peek_len(strp) >= strp->need_bytes)
414 strp->need_bytes = 0;
415 else
416 return;
417 }
418
419 if (strp_read_sock(strp) == -ENOMEM)
420 queue_work(strp_wq, &strp->work);
421}
422EXPORT_SYMBOL_GPL(strp_data_ready);
423
424static void do_strp_work(struct strparser *strp)
425{
426 read_descriptor_t rd_desc;
427
428 /* We need the read lock to synchronize with strp_data_ready. We
429 * need the socket lock for calling strp_read_sock.
430 */
431 strp->cb.lock(strp);
432
433 if (unlikely(strp->stopped))
434 goto out;
435
436 if (strp->paused)
437 goto out;
438
439 rd_desc.arg.data = strp;
440
441 if (strp_read_sock(strp) == -ENOMEM)
442 queue_work(strp_wq, &strp->work);
443
444out:
445 strp->cb.unlock(strp);
446}
447
448static void strp_work(struct work_struct *w)
449{
450 do_strp_work(container_of(w, struct strparser, work));
451}
452
453static void strp_msg_timeout(struct work_struct *w)
454{
455 struct strparser *strp = container_of(w, struct strparser,
456 msg_timer_work.work);
457
458 /* Message assembly timed out */
459 STRP_STATS_INCR(strp->stats.msg_timeouts);
460 strp->cb.lock(strp);
461 strp->cb.abort_parser(strp, ETIMEDOUT);
462 strp->cb.unlock(strp);
463}
464
465static void strp_sock_lock(struct strparser *strp)
466{
467 lock_sock(strp->sk);
468}
469
470static void strp_sock_unlock(struct strparser *strp)
471{
472 release_sock(strp->sk);
473}
474
475int strp_init(struct strparser *strp, struct sock *sk,
476 const struct strp_callbacks *cb)
477{
478
479 if (!cb || !cb->rcv_msg || !cb->parse_msg)
480 return -EINVAL;
481
482 /* The sk (sock) arg determines the mode of the stream parser.
483 *
484 * If the sock is set then the strparser is in receive callback mode.
485 * The upper layer calls strp_data_ready to kick receive processing
486 * and strparser calls the read_sock function on the socket to
487 * get packets.
488 *
489 * If the sock is not set then the strparser is in general mode.
490 * The upper layer calls strp_process for each skb to be parsed.
491 */
492
493 if (!sk) {
494 if (!cb->lock || !cb->unlock)
495 return -EINVAL;
496 }
497
498 memset(strp, 0, sizeof(*strp));
499
500 strp->sk = sk;
501
502 strp->cb.lock = cb->lock ? : strp_sock_lock;
503 strp->cb.unlock = cb->unlock ? : strp_sock_unlock;
504 strp->cb.rcv_msg = cb->rcv_msg;
505 strp->cb.parse_msg = cb->parse_msg;
506 strp->cb.read_sock_done = cb->read_sock_done ? : default_read_sock_done;
507 strp->cb.abort_parser = cb->abort_parser ? : strp_abort_strp;
508
509 INIT_DELAYED_WORK(&strp->msg_timer_work, strp_msg_timeout);
510 INIT_WORK(&strp->work, strp_work);
511
512 return 0;
513}
514EXPORT_SYMBOL_GPL(strp_init);
515
516void strp_unpause(struct strparser *strp)
517{
518 strp->paused = 0;
519
520 /* Sync setting paused with RX work */
521 smp_mb();
522
523 queue_work(strp_wq, &strp->work);
524}
525EXPORT_SYMBOL_GPL(strp_unpause);
526
527/* strp must already be stopped so that strp_recv will no longer be called.
528 * Note that strp_done is not called with the lower socket held.
529 */
530void strp_done(struct strparser *strp)
531{
532 WARN_ON(!strp->stopped);
533
534 cancel_delayed_work_sync(&strp->msg_timer_work);
535 cancel_work_sync(&strp->work);
536
537 if (strp->skb_head) {
538 kfree_skb(strp->skb_head);
539 strp->skb_head = NULL;
540 }
541}
542EXPORT_SYMBOL_GPL(strp_done);
543
544void strp_stop(struct strparser *strp)
545{
546 strp->stopped = 1;
547}
548EXPORT_SYMBOL_GPL(strp_stop);
549
550void strp_check_rcv(struct strparser *strp)
551{
552 queue_work(strp_wq, &strp->work);
553}
554EXPORT_SYMBOL_GPL(strp_check_rcv);
555
556static int __init strp_mod_init(void)
557{
558 strp_wq = create_singlethread_workqueue("kstrp");
559
560 return 0;
561}
562
563static void __exit strp_mod_exit(void)
564{
565 destroy_workqueue(strp_wq);
566}
567module_init(strp_mod_init);
568module_exit(strp_mod_exit);
569MODULE_LICENSE("GPL");