4 * Copyright (c) 2016 Tom Herbert <tom@herbertland.com>
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.
11 #include <linux/bpf.h>
12 #include <linux/errno.h>
13 #include <linux/errqueue.h>
14 #include <linux/file.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>
30 static struct workqueue_struct *strp_wq;
33 /* Internal cb structure. struct strp_msg must be first for passing
40 static inline struct _strp_msg *_strp_msg(struct sk_buff *skb)
42 return (struct _strp_msg *)((void *)skb->cb +
43 offsetof(struct qdisc_skb_cb, data));
47 static void strp_abort_strp(struct strparser *strp, int err)
49 /* Unrecoverable error in receive */
51 cancel_delayed_work(&strp->msg_timer_work);
59 struct sock *sk = strp->sk;
61 /* Report an error on the lower socket */
63 sk->sk_error_report(sk);
67 static void strp_start_timer(struct strparser *strp, long timeo)
69 if (timeo && timeo != LONG_MAX)
70 mod_delayed_work(strp_wq, &strp->msg_timer_work, timeo);
74 static void strp_parser_err(struct strparser *strp, int err,
75 read_descriptor_t *desc)
78 kfree_skb(strp->skb_head);
79 strp->skb_head = NULL;
80 strp->cb.abort_parser(strp, err);
83 static inline int strp_peek_len(struct strparser *strp)
86 struct socket *sock = strp->sk->sk_socket;
88 return sock->ops->peek_len(sock);
91 /* If we don't have an associated socket there's nothing to peek.
92 * Return int max to avoid stopping the strparser.
98 /* Lower socket lock held */
99 static int __strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
100 unsigned int orig_offset, size_t orig_len,
101 size_t max_msg_size, long timeo)
103 struct strparser *strp = (struct strparser *)desc->arg.data;
104 struct _strp_msg *stm;
105 struct sk_buff *head, *skb;
106 size_t eaten = 0, cand_len;
109 bool cloned_orig = false;
114 head = strp->skb_head;
116 /* Message already in progress */
117 if (unlikely(orig_offset)) {
118 /* Getting data with a non-zero offset when a message is
119 * in progress is not expected. If it does happen, we
120 * need to clone and pull since we can't deal with
121 * offsets in the skbs for a message expect in the head.
123 orig_skb = skb_clone(orig_skb, GFP_ATOMIC);
125 STRP_STATS_INCR(strp->stats.mem_fail);
126 desc->error = -ENOMEM;
129 if (!pskb_pull(orig_skb, orig_offset)) {
130 STRP_STATS_INCR(strp->stats.mem_fail);
132 desc->error = -ENOMEM;
139 if (!strp->skb_nextp) {
140 /* We are going to append to the frags_list of head.
141 * Need to unshare the frag_list.
143 if (skb_has_frag_list(head)) {
144 err = skb_unclone(head, GFP_ATOMIC);
146 STRP_STATS_INCR(strp->stats.mem_fail);
152 if (unlikely(skb_shinfo(head)->frag_list)) {
153 /* We can't append to an sk_buff that already
154 * has a frag_list. We create a new head, point
155 * the frag_list of that to the old head, and
156 * then are able to use the old head->next for
157 * appending to the message.
159 if (WARN_ON(head->next)) {
160 desc->error = -EINVAL;
164 skb = alloc_skb(0, GFP_ATOMIC);
166 STRP_STATS_INCR(strp->stats.mem_fail);
167 desc->error = -ENOMEM;
170 skb->len = head->len;
171 skb->data_len = head->len;
172 skb->truesize = head->truesize;
173 *_strp_msg(skb) = *_strp_msg(head);
174 strp->skb_nextp = &head->next;
175 skb_shinfo(skb)->frag_list = head;
176 strp->skb_head = skb;
180 &skb_shinfo(head)->frag_list;
185 while (eaten < orig_len) {
186 /* Always clone since we will consume something */
187 skb = skb_clone(orig_skb, GFP_ATOMIC);
189 STRP_STATS_INCR(strp->stats.mem_fail);
190 desc->error = -ENOMEM;
194 cand_len = orig_len - eaten;
196 head = strp->skb_head;
199 strp->skb_head = head;
200 /* Will set skb_nextp on next packet if needed */
201 strp->skb_nextp = NULL;
202 stm = _strp_msg(head);
203 memset(stm, 0, sizeof(*stm));
204 stm->strp.offset = orig_offset + eaten;
206 /* Unclone if we are appending to an skb that we
207 * already share a frag_list with.
209 if (skb_has_frag_list(skb)) {
210 err = skb_unclone(skb, GFP_ATOMIC);
212 STRP_STATS_INCR(strp->stats.mem_fail);
218 stm = _strp_msg(head);
219 *strp->skb_nextp = skb;
220 strp->skb_nextp = &skb->next;
221 head->data_len += skb->len;
222 head->len += skb->len;
223 head->truesize += skb->truesize;
226 if (!stm->strp.full_len) {
229 len = (*strp->cb.parse_msg)(strp, head);
232 /* Need more header to determine length */
233 if (!stm->accum_len) {
234 /* Start RX timer for new message */
235 strp_start_timer(strp, timeo);
237 stm->accum_len += cand_len;
239 STRP_STATS_INCR(strp->stats.need_more_hdr);
240 WARN_ON(eaten != orig_len);
242 } else if (len < 0) {
243 if (len == -ESTRPIPE && stm->accum_len) {
245 strp->unrecov_intr = 1;
247 strp->interrupted = 1;
249 strp_parser_err(strp, len, desc);
251 } else if (len > max_msg_size) {
252 /* Message length exceeds maximum allowed */
253 STRP_STATS_INCR(strp->stats.msg_too_big);
254 strp_parser_err(strp, -EMSGSIZE, desc);
256 } else if (len <= (ssize_t)head->len -
257 skb->len - stm->strp.offset) {
258 /* Length must be into new skb (and also
261 STRP_STATS_INCR(strp->stats.bad_hdr_len);
262 strp_parser_err(strp, -EPROTO, desc);
266 stm->strp.full_len = len;
269 extra = (ssize_t)(stm->accum_len + cand_len) -
273 /* Message not complete yet. */
274 if (stm->strp.full_len - stm->accum_len >
275 strp_peek_len(strp)) {
276 /* Don't have the whole message in the socket
277 * buffer. Set strp->need_bytes to wait for
278 * the rest of the message. Also, set "early
279 * eaten" since we've already buffered the skb
280 * but don't consume yet per strp_read_sock.
283 if (!stm->accum_len) {
284 /* Start RX timer for new message */
285 strp_start_timer(strp, timeo);
288 stm->accum_len += cand_len;
290 strp->need_bytes = stm->strp.full_len -
292 STRP_STATS_ADD(strp->stats.bytes, cand_len);
293 desc->count = 0; /* Stop reading socket */
296 stm->accum_len += cand_len;
298 WARN_ON(eaten != orig_len);
302 /* Positive extra indicates ore bytes than needed for the
306 WARN_ON(extra > cand_len);
308 eaten += (cand_len - extra);
310 /* Hurray, we have a new message! */
311 cancel_delayed_work(&strp->msg_timer_work);
312 strp->skb_head = NULL;
313 strp->need_bytes = 0;
314 STRP_STATS_INCR(strp->stats.msgs);
316 /* Give skb to upper layer */
317 strp->cb.rcv_msg(strp, head);
319 if (unlikely(strp->paused)) {
320 /* Upper layer paused strp */
328 STRP_STATS_ADD(strp->stats.bytes, eaten);
333 int strp_process(struct strparser *strp, struct sk_buff *orig_skb,
334 unsigned int orig_offset, size_t orig_len,
335 size_t max_msg_size, long timeo)
337 read_descriptor_t desc; /* Dummy arg to strp_recv */
339 desc.arg.data = strp;
341 return __strp_recv(&desc, orig_skb, orig_offset, orig_len,
342 max_msg_size, timeo);
344 EXPORT_SYMBOL_GPL(strp_process);
346 static int strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
347 unsigned int orig_offset, size_t orig_len)
349 struct strparser *strp = (struct strparser *)desc->arg.data;
351 return __strp_recv(desc, orig_skb, orig_offset, orig_len,
352 strp->sk->sk_rcvbuf, strp->sk->sk_rcvtimeo);
355 static int default_read_sock_done(struct strparser *strp, int err)
360 /* Called with lock held on lower socket */
361 static int strp_read_sock(struct strparser *strp)
363 struct socket *sock = strp->sk->sk_socket;
364 read_descriptor_t desc;
366 if (unlikely(!sock || !sock->ops || !sock->ops->read_sock))
369 desc.arg.data = strp;
371 desc.count = 1; /* give more than one skb per call */
373 /* sk should be locked here, so okay to do read_sock */
374 sock->ops->read_sock(strp->sk, &desc, strp_recv);
376 desc.error = strp->cb.read_sock_done(strp, desc.error);
381 /* Lower sock lock held */
382 void strp_data_ready(struct strparser *strp)
384 if (unlikely(strp->stopped) || strp->paused)
387 /* This check is needed to synchronize with do_strp_work.
388 * do_strp_work acquires a process lock (lock_sock) whereas
389 * the lock held here is bh_lock_sock. The two locks can be
390 * held by different threads at the same time, but bh_lock_sock
391 * allows a thread in BH context to safely check if the process
392 * lock is held. In this case, if the lock is held, queue work.
394 if (sock_owned_by_user_nocheck(strp->sk)) {
395 queue_work(strp_wq, &strp->work);
399 if (strp->need_bytes) {
400 if (strp_peek_len(strp) < strp->need_bytes)
404 if (strp_read_sock(strp) == -ENOMEM)
405 queue_work(strp_wq, &strp->work);
407 EXPORT_SYMBOL_GPL(strp_data_ready);
409 static void do_strp_work(struct strparser *strp)
411 /* We need the read lock to synchronize with strp_data_ready. We
412 * need the socket lock for calling strp_read_sock.
416 if (unlikely(strp->stopped))
422 if (strp_read_sock(strp) == -ENOMEM)
423 queue_work(strp_wq, &strp->work);
426 strp->cb.unlock(strp);
429 static void strp_work(struct work_struct *w)
431 do_strp_work(container_of(w, struct strparser, work));
434 static void strp_msg_timeout(struct work_struct *w)
436 struct strparser *strp = container_of(w, struct strparser,
437 msg_timer_work.work);
439 /* Message assembly timed out */
440 STRP_STATS_INCR(strp->stats.msg_timeouts);
442 strp->cb.abort_parser(strp, -ETIMEDOUT);
443 strp->cb.unlock(strp);
446 static void strp_sock_lock(struct strparser *strp)
451 static void strp_sock_unlock(struct strparser *strp)
453 release_sock(strp->sk);
456 int strp_init(struct strparser *strp, struct sock *sk,
457 const struct strp_callbacks *cb)
460 if (!cb || !cb->rcv_msg || !cb->parse_msg)
463 /* The sk (sock) arg determines the mode of the stream parser.
465 * If the sock is set then the strparser is in receive callback mode.
466 * The upper layer calls strp_data_ready to kick receive processing
467 * and strparser calls the read_sock function on the socket to
470 * If the sock is not set then the strparser is in general mode.
471 * The upper layer calls strp_process for each skb to be parsed.
475 if (!cb->lock || !cb->unlock)
479 memset(strp, 0, sizeof(*strp));
483 strp->cb.lock = cb->lock ? : strp_sock_lock;
484 strp->cb.unlock = cb->unlock ? : strp_sock_unlock;
485 strp->cb.rcv_msg = cb->rcv_msg;
486 strp->cb.parse_msg = cb->parse_msg;
487 strp->cb.read_sock_done = cb->read_sock_done ? : default_read_sock_done;
488 strp->cb.abort_parser = cb->abort_parser ? : strp_abort_strp;
490 INIT_DELAYED_WORK(&strp->msg_timer_work, strp_msg_timeout);
491 INIT_WORK(&strp->work, strp_work);
495 EXPORT_SYMBOL_GPL(strp_init);
497 /* Sock process lock held (lock_sock) */
498 void __strp_unpause(struct strparser *strp)
502 if (strp->need_bytes) {
503 if (strp_peek_len(strp) < strp->need_bytes)
506 strp_read_sock(strp);
508 EXPORT_SYMBOL_GPL(__strp_unpause);
510 void strp_unpause(struct strparser *strp)
514 /* Sync setting paused with RX work */
517 queue_work(strp_wq, &strp->work);
519 EXPORT_SYMBOL_GPL(strp_unpause);
521 /* strp must already be stopped so that strp_recv will no longer be called.
522 * Note that strp_done is not called with the lower socket held.
524 void strp_done(struct strparser *strp)
526 WARN_ON(!strp->stopped);
528 cancel_delayed_work_sync(&strp->msg_timer_work);
529 cancel_work_sync(&strp->work);
531 if (strp->skb_head) {
532 kfree_skb(strp->skb_head);
533 strp->skb_head = NULL;
536 EXPORT_SYMBOL_GPL(strp_done);
538 void strp_stop(struct strparser *strp)
542 EXPORT_SYMBOL_GPL(strp_stop);
544 void strp_check_rcv(struct strparser *strp)
546 queue_work(strp_wq, &strp->work);
548 EXPORT_SYMBOL_GPL(strp_check_rcv);
550 static int __init strp_mod_init(void)
552 strp_wq = create_singlethread_workqueue("kstrp");
557 static void __exit strp_mod_exit(void)
559 destroy_workqueue(strp_wq);
561 module_init(strp_mod_init);
562 module_exit(strp_mod_exit);
563 MODULE_LICENSE("GPL");