1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (c) 2016 Tom Herbert <tom@herbertland.com>
9 #include <linux/errno.h>
10 #include <linux/errqueue.h>
11 #include <linux/file.h>
13 #include <linux/kernel.h>
14 #include <linux/export.h>
15 #include <linux/init.h>
16 #include <linux/net.h>
17 #include <linux/netdevice.h>
18 #include <linux/poll.h>
19 #include <linux/rculist.h>
20 #include <linux/skbuff.h>
21 #include <linux/socket.h>
22 #include <linux/uaccess.h>
23 #include <linux/workqueue.h>
24 #include <net/strparser.h>
25 #include <net/netns/generic.h>
28 static struct workqueue_struct *strp_wq;
30 static inline struct _strp_msg *_strp_msg(struct sk_buff *skb)
32 return (struct _strp_msg *)((void *)skb->cb +
33 offsetof(struct sk_skb_cb, strp));
37 static void strp_abort_strp(struct strparser *strp, int err)
39 /* Unrecoverable error in receive */
41 cancel_delayed_work(&strp->msg_timer_work);
49 struct sock *sk = strp->sk;
51 /* Report an error on the lower socket */
57 static void strp_start_timer(struct strparser *strp, long timeo)
59 if (timeo && timeo != LONG_MAX)
60 mod_delayed_work(strp_wq, &strp->msg_timer_work, timeo);
64 static void strp_parser_err(struct strparser *strp, int err,
65 read_descriptor_t *desc)
68 kfree_skb(strp->skb_head);
69 strp->skb_head = NULL;
70 strp->cb.abort_parser(strp, err);
73 static inline int strp_peek_len(struct strparser *strp)
76 struct socket *sock = strp->sk->sk_socket;
78 return sock->ops->peek_len(sock);
81 /* If we don't have an associated socket there's nothing to peek.
82 * Return int max to avoid stopping the strparser.
88 /* Lower socket lock held */
89 static int __strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
90 unsigned int orig_offset, size_t orig_len,
91 size_t max_msg_size, long timeo)
93 struct strparser *strp = (struct strparser *)desc->arg.data;
94 struct _strp_msg *stm;
95 struct sk_buff *head, *skb;
96 size_t eaten = 0, cand_len;
99 bool cloned_orig = false;
104 head = strp->skb_head;
106 /* Message already in progress */
107 if (unlikely(orig_offset)) {
108 /* Getting data with a non-zero offset when a message is
109 * in progress is not expected. If it does happen, we
110 * need to clone and pull since we can't deal with
111 * offsets in the skbs for a message expect in the head.
113 orig_skb = skb_clone(orig_skb, GFP_ATOMIC);
115 STRP_STATS_INCR(strp->stats.mem_fail);
116 desc->error = -ENOMEM;
119 if (!pskb_pull(orig_skb, orig_offset)) {
120 STRP_STATS_INCR(strp->stats.mem_fail);
122 desc->error = -ENOMEM;
129 if (!strp->skb_nextp) {
130 /* We are going to append to the frags_list of head.
131 * Need to unshare the frag_list.
133 err = skb_unclone(head, GFP_ATOMIC);
135 STRP_STATS_INCR(strp->stats.mem_fail);
140 if (unlikely(skb_shinfo(head)->frag_list)) {
141 /* We can't append to an sk_buff that already
142 * has a frag_list. We create a new head, point
143 * the frag_list of that to the old head, and
144 * then are able to use the old head->next for
145 * appending to the message.
147 if (WARN_ON(head->next)) {
148 desc->error = -EINVAL;
152 skb = alloc_skb_for_msg(head);
154 STRP_STATS_INCR(strp->stats.mem_fail);
155 desc->error = -ENOMEM;
159 strp->skb_nextp = &head->next;
160 strp->skb_head = skb;
164 &skb_shinfo(head)->frag_list;
169 while (eaten < orig_len) {
170 /* Always clone since we will consume something */
171 skb = skb_clone(orig_skb, GFP_ATOMIC);
173 STRP_STATS_INCR(strp->stats.mem_fail);
174 desc->error = -ENOMEM;
178 cand_len = orig_len - eaten;
180 head = strp->skb_head;
183 strp->skb_head = head;
184 /* Will set skb_nextp on next packet if needed */
185 strp->skb_nextp = NULL;
186 stm = _strp_msg(head);
187 memset(stm, 0, sizeof(*stm));
188 stm->strp.offset = orig_offset + eaten;
190 /* Unclone if we are appending to an skb that we
191 * already share a frag_list with.
193 if (skb_has_frag_list(skb)) {
194 err = skb_unclone(skb, GFP_ATOMIC);
196 STRP_STATS_INCR(strp->stats.mem_fail);
202 stm = _strp_msg(head);
203 *strp->skb_nextp = skb;
204 strp->skb_nextp = &skb->next;
205 head->data_len += skb->len;
206 head->len += skb->len;
207 head->truesize += skb->truesize;
210 if (!stm->strp.full_len) {
213 len = (*strp->cb.parse_msg)(strp, head);
216 /* Need more header to determine length */
217 if (!stm->accum_len) {
218 /* Start RX timer for new message */
219 strp_start_timer(strp, timeo);
221 stm->accum_len += cand_len;
223 STRP_STATS_INCR(strp->stats.need_more_hdr);
224 WARN_ON(eaten != orig_len);
226 } else if (len < 0) {
227 if (len == -ESTRPIPE && stm->accum_len) {
229 strp->unrecov_intr = 1;
231 strp->interrupted = 1;
233 strp_parser_err(strp, len, desc);
235 } else if (len > max_msg_size) {
236 /* Message length exceeds maximum allowed */
237 STRP_STATS_INCR(strp->stats.msg_too_big);
238 strp_parser_err(strp, -EMSGSIZE, desc);
240 } else if (len <= (ssize_t)head->len -
241 skb->len - stm->strp.offset) {
242 /* Length must be into new skb (and also
245 STRP_STATS_INCR(strp->stats.bad_hdr_len);
246 strp_parser_err(strp, -EPROTO, desc);
250 stm->strp.full_len = len;
253 extra = (ssize_t)(stm->accum_len + cand_len) -
257 /* Message not complete yet. */
258 if (stm->strp.full_len - stm->accum_len >
259 strp_peek_len(strp)) {
260 /* Don't have the whole message in the socket
261 * buffer. Set strp->need_bytes to wait for
262 * the rest of the message. Also, set "early
263 * eaten" since we've already buffered the skb
264 * but don't consume yet per strp_read_sock.
267 if (!stm->accum_len) {
268 /* Start RX timer for new message */
269 strp_start_timer(strp, timeo);
272 stm->accum_len += cand_len;
274 strp->need_bytes = stm->strp.full_len -
276 STRP_STATS_ADD(strp->stats.bytes, cand_len);
277 desc->count = 0; /* Stop reading socket */
280 stm->accum_len += cand_len;
282 WARN_ON(eaten != orig_len);
286 /* Positive extra indicates more bytes than needed for the
290 WARN_ON(extra > cand_len);
292 eaten += (cand_len - extra);
294 /* Hurray, we have a new message! */
295 cancel_delayed_work(&strp->msg_timer_work);
296 strp->skb_head = NULL;
297 strp->need_bytes = 0;
298 STRP_STATS_INCR(strp->stats.msgs);
300 /* Give skb to upper layer */
301 strp->cb.rcv_msg(strp, head);
303 if (unlikely(strp->paused)) {
304 /* Upper layer paused strp */
312 STRP_STATS_ADD(strp->stats.bytes, eaten);
317 int strp_process(struct strparser *strp, struct sk_buff *orig_skb,
318 unsigned int orig_offset, size_t orig_len,
319 size_t max_msg_size, long timeo)
321 read_descriptor_t desc; /* Dummy arg to strp_recv */
323 desc.arg.data = strp;
325 return __strp_recv(&desc, orig_skb, orig_offset, orig_len,
326 max_msg_size, timeo);
328 EXPORT_SYMBOL_GPL(strp_process);
330 static int strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
331 unsigned int orig_offset, size_t orig_len)
333 struct strparser *strp = (struct strparser *)desc->arg.data;
335 return __strp_recv(desc, orig_skb, orig_offset, orig_len,
336 strp->sk->sk_rcvbuf, strp->sk->sk_rcvtimeo);
339 static int default_read_sock_done(struct strparser *strp, int err)
344 /* Called with lock held on lower socket */
345 static int strp_read_sock(struct strparser *strp)
347 struct socket *sock = strp->sk->sk_socket;
348 read_descriptor_t desc;
350 if (unlikely(!sock || !sock->ops || !sock->ops->read_sock))
353 desc.arg.data = strp;
355 desc.count = 1; /* give more than one skb per call */
357 /* sk should be locked here, so okay to do read_sock */
358 sock->ops->read_sock(strp->sk, &desc, strp_recv);
360 desc.error = strp->cb.read_sock_done(strp, desc.error);
365 /* Lower sock lock held */
366 void strp_data_ready(struct strparser *strp)
368 if (unlikely(strp->stopped) || strp->paused)
371 /* This check is needed to synchronize with do_strp_work.
372 * do_strp_work acquires a process lock (lock_sock) whereas
373 * the lock held here is bh_lock_sock. The two locks can be
374 * held by different threads at the same time, but bh_lock_sock
375 * allows a thread in BH context to safely check if the process
376 * lock is held. In this case, if the lock is held, queue work.
378 if (sock_owned_by_user_nocheck(strp->sk)) {
379 queue_work(strp_wq, &strp->work);
383 if (strp->need_bytes) {
384 if (strp_peek_len(strp) < strp->need_bytes)
388 if (strp_read_sock(strp) == -ENOMEM)
389 queue_work(strp_wq, &strp->work);
391 EXPORT_SYMBOL_GPL(strp_data_ready);
393 static void do_strp_work(struct strparser *strp)
395 /* We need the read lock to synchronize with strp_data_ready. We
396 * need the socket lock for calling strp_read_sock.
400 if (unlikely(strp->stopped))
406 if (strp_read_sock(strp) == -ENOMEM)
407 queue_work(strp_wq, &strp->work);
410 strp->cb.unlock(strp);
413 static void strp_work(struct work_struct *w)
415 do_strp_work(container_of(w, struct strparser, work));
418 static void strp_msg_timeout(struct work_struct *w)
420 struct strparser *strp = container_of(w, struct strparser,
421 msg_timer_work.work);
423 /* Message assembly timed out */
424 STRP_STATS_INCR(strp->stats.msg_timeouts);
426 strp->cb.abort_parser(strp, -ETIMEDOUT);
427 strp->cb.unlock(strp);
430 static void strp_sock_lock(struct strparser *strp)
435 static void strp_sock_unlock(struct strparser *strp)
437 release_sock(strp->sk);
440 int strp_init(struct strparser *strp, struct sock *sk,
441 const struct strp_callbacks *cb)
444 if (!cb || !cb->rcv_msg || !cb->parse_msg)
447 /* The sk (sock) arg determines the mode of the stream parser.
449 * If the sock is set then the strparser is in receive callback mode.
450 * The upper layer calls strp_data_ready to kick receive processing
451 * and strparser calls the read_sock function on the socket to
454 * If the sock is not set then the strparser is in general mode.
455 * The upper layer calls strp_process for each skb to be parsed.
459 if (!cb->lock || !cb->unlock)
463 memset(strp, 0, sizeof(*strp));
467 strp->cb.lock = cb->lock ? : strp_sock_lock;
468 strp->cb.unlock = cb->unlock ? : strp_sock_unlock;
469 strp->cb.rcv_msg = cb->rcv_msg;
470 strp->cb.parse_msg = cb->parse_msg;
471 strp->cb.read_sock_done = cb->read_sock_done ? : default_read_sock_done;
472 strp->cb.abort_parser = cb->abort_parser ? : strp_abort_strp;
474 INIT_DELAYED_WORK(&strp->msg_timer_work, strp_msg_timeout);
475 INIT_WORK(&strp->work, strp_work);
479 EXPORT_SYMBOL_GPL(strp_init);
481 /* Sock process lock held (lock_sock) */
482 void __strp_unpause(struct strparser *strp)
486 if (strp->need_bytes) {
487 if (strp_peek_len(strp) < strp->need_bytes)
490 strp_read_sock(strp);
492 EXPORT_SYMBOL_GPL(__strp_unpause);
494 void strp_unpause(struct strparser *strp)
498 /* Sync setting paused with RX work */
501 queue_work(strp_wq, &strp->work);
503 EXPORT_SYMBOL_GPL(strp_unpause);
505 /* strp must already be stopped so that strp_recv will no longer be called.
506 * Note that strp_done is not called with the lower socket held.
508 void strp_done(struct strparser *strp)
510 WARN_ON(!strp->stopped);
512 cancel_delayed_work_sync(&strp->msg_timer_work);
513 cancel_work_sync(&strp->work);
515 if (strp->skb_head) {
516 kfree_skb(strp->skb_head);
517 strp->skb_head = NULL;
520 EXPORT_SYMBOL_GPL(strp_done);
522 void strp_stop(struct strparser *strp)
526 EXPORT_SYMBOL_GPL(strp_stop);
528 void strp_check_rcv(struct strparser *strp)
530 queue_work(strp_wq, &strp->work);
532 EXPORT_SYMBOL_GPL(strp_check_rcv);
534 static int __init strp_dev_init(void)
536 strp_wq = create_singlethread_workqueue("kstrp");
537 if (unlikely(!strp_wq))
542 device_initcall(strp_dev_init);