net/strparser/strparser.c - kernel/msm-4.9 - Gitiles

 /*
  * Stream Parser
  *
  * Copyright (c) 2016 Tom Herbert <tom@herbertland.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2
  * as published by the Free Software Foundation.
  */

 #include <linux/bpf.h>
 #include <linux/errno.h>
 #include <linux/errqueue.h>
 #include <linux/file.h>
 #include <linux/in.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/net.h>
 #include <linux/netdevice.h>
 #include <linux/poll.h>
 #include <linux/rculist.h>
 #include <linux/skbuff.h>
 #include <linux/socket.h>
 #include <linux/uaccess.h>
 #include <linux/workqueue.h>
 #include <net/strparser.h>
 #include <net/netns/generic.h>
 #include <net/sock.h>

 static struct workqueue_struct *strp_wq;

 struct _strp_rx_msg {
 	/* Internal cb structure. struct strp_rx_msg must be first for passing
 	 * to upper layer.
 	 */
 	struct strp_rx_msg strp;
 	int accum_len;
 	int early_eaten;
 };

 static inline struct _strp_rx_msg *_strp_rx_msg(struct sk_buff *skb)
 {
 	return (struct _strp_rx_msg *)((void *)skb->cb +
 		offsetof(struct qdisc_skb_cb, data));
 }

 /* Lower lock held */
 static void strp_abort_rx_strp(struct strparser *strp, int err)
 {
 	struct sock *csk = strp->sk;

 	/* Unrecoverable error in receive */

 	del_timer(&strp->rx_msg_timer);

 	if (strp->rx_stopped)
 		return;

 	strp->rx_stopped = 1;

 	/* Report an error on the lower socket */
 	csk->sk_err = -err;
 	csk->sk_error_report(csk);
 }

 static void strp_start_rx_timer(struct strparser *strp)
 {
 	if (strp->sk->sk_rcvtimeo)
 		mod_timer(&strp->rx_msg_timer, strp->sk->sk_rcvtimeo);
 }

 /* Lower lock held */
 static void strp_parser_err(struct strparser *strp, int err,
 			    read_descriptor_t *desc)
 {
 	desc->error = err;
 	kfree_skb(strp->rx_skb_head);
 	strp->rx_skb_head = NULL;
 	strp->cb.abort_parser(strp, err);
 }

 static inline int strp_peek_len(struct strparser *strp)
 {
 	struct socket *sock = strp->sk->sk_socket;

 	return sock->ops->peek_len(sock);
 }

 /* Lower socket lock held */
 static int strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
 		     unsigned int orig_offset, size_t orig_len)
 {
 	struct strparser *strp = (struct strparser *)desc->arg.data;
 	struct _strp_rx_msg *rxm;
 	struct sk_buff *head, *skb;
 	size_t eaten = 0, cand_len;
 	ssize_t extra;
 	int err;
 	bool cloned_orig = false;

 	if (strp->rx_paused)
 		return 0;

 	head = strp->rx_skb_head;
 	if (head) {
 		/* Message already in progress */

 		rxm = _strp_rx_msg(head);
 		if (unlikely(rxm->early_eaten)) {
 			/* Already some number of bytes on the receive sock
 			 * data saved in rx_skb_head, just indicate they
 			 * are consumed.
 			 */
 			eaten = orig_len <= rxm->early_eaten ?
 				orig_len : rxm->early_eaten;
 			rxm->early_eaten -= eaten;

 			return eaten;
 		}

 		if (unlikely(orig_offset)) {
 			/* Getting data with a non-zero offset when a message is
 			 * in progress is not expected. If it does happen, we
 			 * need to clone and pull since we can't deal with
 			 * offsets in the skbs for a message expect in the head.
 			 */
 			orig_skb = skb_clone(orig_skb, GFP_ATOMIC);
 			if (!orig_skb) {
 				STRP_STATS_INCR(strp->stats.rx_mem_fail);
 				desc->error = -ENOMEM;
 				return 0;
 			}
 			if (!pskb_pull(orig_skb, orig_offset)) {
 				STRP_STATS_INCR(strp->stats.rx_mem_fail);
 				kfree_skb(orig_skb);
 				desc->error = -ENOMEM;
 				return 0;
 			}
 			cloned_orig = true;
 			orig_offset = 0;
 		}

 		if (!strp->rx_skb_nextp) {
 			/* We are going to append to the frags_list of head.
 			 * Need to unshare the frag_list.
 			 */
 			err = skb_unclone(head, GFP_ATOMIC);
 			if (err) {
 				STRP_STATS_INCR(strp->stats.rx_mem_fail);
 				desc->error = err;
 				return 0;
 			}

 			if (unlikely(skb_shinfo(head)->frag_list)) {
 				/* We can't append to an sk_buff that already
 				 * has a frag_list. We create a new head, point
 				 * the frag_list of that to the old head, and
 				 * then are able to use the old head->next for
 				 * appending to the message.
 				 */
 				if (WARN_ON(head->next)) {
 					desc->error = -EINVAL;
 					return 0;
 				}

 				skb = alloc_skb(0, GFP_ATOMIC);
 				if (!skb) {
 					STRP_STATS_INCR(strp->stats.rx_mem_fail);
 					desc->error = -ENOMEM;
 					return 0;
 				}
 				skb->len = head->len;
 				skb->data_len = head->len;
 				skb->truesize = head->truesize;
 				*_strp_rx_msg(skb) = *_strp_rx_msg(head);
 				strp->rx_skb_nextp = &head->next;
 				skb_shinfo(skb)->frag_list = head;
 				strp->rx_skb_head = skb;
 				head = skb;
 			} else {
 				strp->rx_skb_nextp =
 				    &skb_shinfo(head)->frag_list;
 			}
 		}
 	}

 	while (eaten < orig_len) {
 		/* Always clone since we will consume something */
 		skb = skb_clone(orig_skb, GFP_ATOMIC);
 		if (!skb) {
 			STRP_STATS_INCR(strp->stats.rx_mem_fail);
 			desc->error = -ENOMEM;
 			break;
 		}

 		cand_len = orig_len - eaten;

 		head = strp->rx_skb_head;
 		if (!head) {
 			head = skb;
 			strp->rx_skb_head = head;
 			/* Will set rx_skb_nextp on next packet if needed */
 			strp->rx_skb_nextp = NULL;
 			rxm = _strp_rx_msg(head);
 			memset(rxm, 0, sizeof(*rxm));
 			rxm->strp.offset = orig_offset + eaten;
 		} else {
 			/* Unclone since we may be appending to an skb that we
 			 * already share a frag_list with.
 			 */
 			err = skb_unclone(skb, GFP_ATOMIC);
 			if (err) {
 				STRP_STATS_INCR(strp->stats.rx_mem_fail);
 				desc->error = err;
 				break;
 			}

 			rxm = _strp_rx_msg(head);
 			*strp->rx_skb_nextp = skb;
 			strp->rx_skb_nextp = &skb->next;
 			head->data_len += skb->len;
 			head->len += skb->len;
 			head->truesize += skb->truesize;
 		}

 		if (!rxm->strp.full_len) {
 			ssize_t len;

 			len = (*strp->cb.parse_msg)(strp, head);

 			if (!len) {
 				/* Need more header to determine length */
 				if (!rxm->accum_len) {
 					/* Start RX timer for new message */
 					strp_start_rx_timer(strp);
 				}
 				rxm->accum_len += cand_len;
 				eaten += cand_len;
 				STRP_STATS_INCR(strp->stats.rx_need_more_hdr);
 				WARN_ON(eaten != orig_len);
 				break;
 			} else if (len < 0) {
 				if (len == -ESTRPIPE && rxm->accum_len) {
 					len = -ENODATA;
 					strp->rx_unrecov_intr = 1;
 				} else {
 					strp->rx_interrupted = 1;
 				}
 				strp_parser_err(strp, len, desc);
 				break;
 			} else if (len > strp->sk->sk_rcvbuf) {
 				/* Message length exceeds maximum allowed */
 				STRP_STATS_INCR(strp->stats.rx_msg_too_big);
 				strp_parser_err(strp, -EMSGSIZE, desc);
 				break;
 			} else if (len <= (ssize_t)head->len -
 					  skb->len - rxm->strp.offset) {
 				/* Length must be into new skb (and also
 				 * greater than zero)
 				 */
 				STRP_STATS_INCR(strp->stats.rx_bad_hdr_len);
 				strp_parser_err(strp, -EPROTO, desc);
 				break;
 			}

 			rxm->strp.full_len = len;
 		}

 		extra = (ssize_t)(rxm->accum_len + cand_len) -
 			rxm->strp.full_len;

 		if (extra < 0) {
 			/* Message not complete yet. */
 			if (rxm->strp.full_len - rxm->accum_len >
 			    strp_peek_len(strp)) {
 				/* Don't have the whole messages in the socket
 				 * buffer. Set strp->rx_need_bytes to wait for
 				 * the rest of the message. Also, set "early
 				 * eaten" since we've already buffered the skb
 				 * but don't consume yet per strp_read_sock.
 				 */

 				if (!rxm->accum_len) {
 					/* Start RX timer for new message */
 					strp_start_rx_timer(strp);
 				}

 				rxm->accum_len += cand_len;
 				strp->rx_need_bytes = rxm->strp.full_len -
 						       rxm->accum_len;
 				rxm->early_eaten = cand_len;
 				STRP_STATS_ADD(strp->stats.rx_bytes, cand_len);
 				desc->count = 0; /* Stop reading socket */
 				break;
 			}
 			rxm->accum_len += cand_len;
 			eaten += cand_len;
 			WARN_ON(eaten != orig_len);
 			break;
 		}

 		/* Positive extra indicates ore bytes than needed for the
 		 * message
 		 */

 		WARN_ON(extra > cand_len);

 		eaten += (cand_len - extra);

 		/* Hurray, we have a new message! */
 		del_timer(&strp->rx_msg_timer);
 		strp->rx_skb_head = NULL;
 		strp->rx_need_bytes = 0;
 		STRP_STATS_INCR(strp->stats.rx_msgs);

 		/* Give skb to upper layer */
 		strp->cb.rcv_msg(strp, head);

 		if (unlikely(strp->rx_paused)) {
 			/* Upper layer paused strp */
 			break;
 		}
 	}

 	if (cloned_orig)
 		kfree_skb(orig_skb);

 	STRP_STATS_ADD(strp->stats.rx_bytes, eaten);

 	return eaten;
 }

 static int default_read_sock_done(struct strparser *strp, int err)
 {
 	return err;
 }

 /* Called with lock held on lower socket */
 static int strp_read_sock(struct strparser *strp)
 {
 	struct socket *sock = strp->sk->sk_socket;
 	read_descriptor_t desc;

 	desc.arg.data = strp;
 	desc.error = 0;
 	desc.count = 1; /* give more than one skb per call */

 	/* sk should be locked here, so okay to do read_sock */
 	sock->ops->read_sock(strp->sk, &desc, strp_recv);

 	desc.error = strp->cb.read_sock_done(strp, desc.error);

 	return desc.error;
 }

 /* Lower sock lock held */
 void strp_data_ready(struct strparser *strp)
 {
 	if (unlikely(strp->rx_stopped))
 		return;

 	/* This check is needed to synchronize with do_strp_rx_work.
 	 * do_strp_rx_work acquires a process lock (lock_sock) whereas
 	 * the lock held here is bh_lock_sock. The two locks can be
 	 * held by different threads at the same time, but bh_lock_sock
 	 * allows a thread in BH context to safely check if the process
 	 * lock is held. In this case, if the lock is held, queue work.
 	 */
 	if (sock_owned_by_user(strp->sk)) {
 		queue_work(strp_wq, &strp->rx_work);
 		return;
 	}

 	if (strp->rx_paused)
 		return;

 	if (strp->rx_need_bytes) {
 		if (strp_peek_len(strp) < strp->rx_need_bytes)
 			return;
 	}

 	if (strp_read_sock(strp) == -ENOMEM)
 		queue_work(strp_wq, &strp->rx_work);
 }
 EXPORT_SYMBOL_GPL(strp_data_ready);

 static void do_strp_rx_work(struct strparser *strp)
 {
 	read_descriptor_t rd_desc;
 	struct sock *csk = strp->sk;

 	/* We need the read lock to synchronize with strp_data_ready. We
 	 * need the socket lock for calling strp_read_sock.
 	 */
 	lock_sock(csk);

 	if (unlikely(strp->rx_stopped))
 		goto out;

 	if (strp->rx_paused)
 		goto out;

 	rd_desc.arg.data = strp;

 	if (strp_read_sock(strp) == -ENOMEM)
 		queue_work(strp_wq, &strp->rx_work);

 out:
 	release_sock(csk);
 }

 static void strp_rx_work(struct work_struct *w)
 {
 	do_strp_rx_work(container_of(w, struct strparser, rx_work));
 }

 static void strp_rx_msg_timeout(unsigned long arg)
 {
 	struct strparser *strp = (struct strparser *)arg;

 	/* Message assembly timed out */
 	STRP_STATS_INCR(strp->stats.rx_msg_timeouts);
 	lock_sock(strp->sk);
 	strp->cb.abort_parser(strp, -ETIMEDOUT);
 	release_sock(strp->sk);
 }

 int strp_init(struct strparser *strp, struct sock *csk,
 	      struct strp_callbacks *cb)
 {
 	struct socket *sock = csk->sk_socket;

 	if (!cb || !cb->rcv_msg || !cb->parse_msg)
 		return -EINVAL;

 	if (!sock->ops->read_sock || !sock->ops->peek_len)
 		return -EAFNOSUPPORT;

 	memset(strp, 0, sizeof(*strp));

 	strp->sk = csk;

 	setup_timer(&strp->rx_msg_timer, strp_rx_msg_timeout,
 		    (unsigned long)strp);

 	INIT_WORK(&strp->rx_work, strp_rx_work);

 	strp->cb.rcv_msg = cb->rcv_msg;
 	strp->cb.parse_msg = cb->parse_msg;
 	strp->cb.read_sock_done = cb->read_sock_done ? : default_read_sock_done;
 	strp->cb.abort_parser = cb->abort_parser ? : strp_abort_rx_strp;

 	return 0;
 }
 EXPORT_SYMBOL_GPL(strp_init);

 void strp_unpause(struct strparser *strp)
 {
 	strp->rx_paused = 0;

 	/* Sync setting rx_paused with RX work */
 	smp_mb();

 	queue_work(strp_wq, &strp->rx_work);
 }
 EXPORT_SYMBOL_GPL(strp_unpause);

 /* strp must already be stopped so that strp_recv will no longer be called.
  * Note that strp_done is not called with the lower socket held.
  */
 void strp_done(struct strparser *strp)
 {
 	WARN_ON(!strp->rx_stopped);

 	del_timer_sync(&strp->rx_msg_timer);
 	cancel_work_sync(&strp->rx_work);

 	if (strp->rx_skb_head) {
 		kfree_skb(strp->rx_skb_head);
 		strp->rx_skb_head = NULL;
 	}
 }
 EXPORT_SYMBOL_GPL(strp_done);

 void strp_stop(struct strparser *strp)
 {
 	strp->rx_stopped = 1;
 }
 EXPORT_SYMBOL_GPL(strp_stop);

 void strp_check_rcv(struct strparser *strp)
 {
 	queue_work(strp_wq, &strp->rx_work);
 }
 EXPORT_SYMBOL_GPL(strp_check_rcv);

 static int __init strp_mod_init(void)
 {
 	strp_wq = create_singlethread_workqueue("kstrp");

 	return 0;
 }

 static void __exit strp_mod_exit(void)
 {
 	destroy_workqueue(strp_wq);
 }
 module_init(strp_mod_init);
 module_exit(strp_mod_exit);
 MODULE_LICENSE("GPL");
	/*
	* Stream Parser
	*
	* Copyright (c) 2016 Tom Herbert <tom@herbertland.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2
	* as published by the Free Software Foundation.
	*/

	#include <linux/bpf.h>
	#include <linux/errno.h>
	#include <linux/errqueue.h>
	#include <linux/file.h>
	#include <linux/in.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/net.h>
	#include <linux/netdevice.h>
	#include <linux/poll.h>
	#include <linux/rculist.h>
	#include <linux/skbuff.h>
	#include <linux/socket.h>
	#include <linux/uaccess.h>
	#include <linux/workqueue.h>
	#include <net/strparser.h>
	#include <net/netns/generic.h>
	#include <net/sock.h>

	static struct workqueue_struct *strp_wq;

	struct _strp_rx_msg {
	/* Internal cb structure. struct strp_rx_msg must be first for passing
	* to upper layer.
	*/
	struct strp_rx_msg strp;
	int accum_len;
	int early_eaten;
	};

	static inline struct _strp_rx_msg _strp_rx_msg(struct sk_buff skb)
	{
	return (struct _strp_rx_msg )((void )skb->cb +
	offsetof(struct qdisc_skb_cb, data));
	}

	/* Lower lock held */
	static void strp_abort_rx_strp(struct strparser *strp, int err)
	{
	struct sock *csk = strp->sk;

	/* Unrecoverable error in receive */

	del_timer(&strp->rx_msg_timer);

	if (strp->rx_stopped)
	return;

	strp->rx_stopped = 1;

	/* Report an error on the lower socket */
	csk->sk_err = -err;
	csk->sk_error_report(csk);
	}

	static void strp_start_rx_timer(struct strparser *strp)
	{
	if (strp->sk->sk_rcvtimeo)
	mod_timer(&strp->rx_msg_timer, strp->sk->sk_rcvtimeo);
	}

	/* Lower lock held */
	static void strp_parser_err(struct strparser *strp, int err,
	read_descriptor_t *desc)
	{
	desc->error = err;
	kfree_skb(strp->rx_skb_head);
	strp->rx_skb_head = NULL;
	strp->cb.abort_parser(strp, err);
	}

	static inline int strp_peek_len(struct strparser *strp)
	{
	struct socket *sock = strp->sk->sk_socket;

	return sock->ops->peek_len(sock);
	}

	/* Lower socket lock held */
	static int strp_recv(read_descriptor_t desc, struct sk_buff orig_skb,
	unsigned int orig_offset, size_t orig_len)
	{
	struct strparser strp = (struct strparser )desc->arg.data;
	struct _strp_rx_msg *rxm;
	struct sk_buff head, skb;
	size_t eaten = 0, cand_len;
	ssize_t extra;
	int err;
	bool cloned_orig = false;

	if (strp->rx_paused)
	return 0;

	head = strp->rx_skb_head;
	if (head) {
	/* Message already in progress */

	rxm = _strp_rx_msg(head);
	if (unlikely(rxm->early_eaten)) {
	/* Already some number of bytes on the receive sock
	* data saved in rx_skb_head, just indicate they
	* are consumed.
	*/
	eaten = orig_len <= rxm->early_eaten ?
	orig_len : rxm->early_eaten;
	rxm->early_eaten -= eaten;

	return eaten;
	}

	if (unlikely(orig_offset)) {
	/* Getting data with a non-zero offset when a message is
	* in progress is not expected. If it does happen, we
	* need to clone and pull since we can't deal with
	* offsets in the skbs for a message expect in the head.
	*/
	orig_skb = skb_clone(orig_skb, GFP_ATOMIC);
	if (!orig_skb) {
	STRP_STATS_INCR(strp->stats.rx_mem_fail);
	desc->error = -ENOMEM;
	return 0;
	}
	if (!pskb_pull(orig_skb, orig_offset)) {
	STRP_STATS_INCR(strp->stats.rx_mem_fail);
	kfree_skb(orig_skb);
	desc->error = -ENOMEM;
	return 0;
	}
	cloned_orig = true;
	orig_offset = 0;
	}

	if (!strp->rx_skb_nextp) {
	/* We are going to append to the frags_list of head.
	* Need to unshare the frag_list.
	*/
	err = skb_unclone(head, GFP_ATOMIC);
	if (err) {
	STRP_STATS_INCR(strp->stats.rx_mem_fail);
	desc->error = err;
	return 0;
	}

	if (unlikely(skb_shinfo(head)->frag_list)) {
	/* We can't append to an sk_buff that already
	* has a frag_list. We create a new head, point
	* the frag_list of that to the old head, and
	* then are able to use the old head->next for
	* appending to the message.
	*/
	if (WARN_ON(head->next)) {
	desc->error = -EINVAL;
	return 0;
	}

	skb = alloc_skb(0, GFP_ATOMIC);
	if (!skb) {
	STRP_STATS_INCR(strp->stats.rx_mem_fail);
	desc->error = -ENOMEM;
	return 0;
	}
	skb->len = head->len;
	skb->data_len = head->len;
	skb->truesize = head->truesize;
	_strp_rx_msg(skb) = _strp_rx_msg(head);
	strp->rx_skb_nextp = &head->next;
	skb_shinfo(skb)->frag_list = head;
	strp->rx_skb_head = skb;
	head = skb;
	} else {
	strp->rx_skb_nextp =
	&skb_shinfo(head)->frag_list;
	}
	}
	}

	while (eaten < orig_len) {
	/* Always clone since we will consume something */
	skb = skb_clone(orig_skb, GFP_ATOMIC);
	if (!skb) {
	STRP_STATS_INCR(strp->stats.rx_mem_fail);
	desc->error = -ENOMEM;
	break;
	}

	cand_len = orig_len - eaten;

	head = strp->rx_skb_head;
	if (!head) {
	head = skb;
	strp->rx_skb_head = head;
	/* Will set rx_skb_nextp on next packet if needed */
	strp->rx_skb_nextp = NULL;
	rxm = _strp_rx_msg(head);
	memset(rxm, 0, sizeof(*rxm));
	rxm->strp.offset = orig_offset + eaten;
	} else {
	/* Unclone since we may be appending to an skb that we
	* already share a frag_list with.
	*/
	err = skb_unclone(skb, GFP_ATOMIC);
	if (err) {
	STRP_STATS_INCR(strp->stats.rx_mem_fail);
	desc->error = err;
	break;
	}

	rxm = _strp_rx_msg(head);
	*strp->rx_skb_nextp = skb;
	strp->rx_skb_nextp = &skb->next;
	head->data_len += skb->len;
	head->len += skb->len;
	head->truesize += skb->truesize;
	}

	if (!rxm->strp.full_len) {
	ssize_t len;

	len = (*strp->cb.parse_msg)(strp, head);

	if (!len) {
	/* Need more header to determine length */
	if (!rxm->accum_len) {
	/* Start RX timer for new message */
	strp_start_rx_timer(strp);
	}
	rxm->accum_len += cand_len;
	eaten += cand_len;
	STRP_STATS_INCR(strp->stats.rx_need_more_hdr);
	WARN_ON(eaten != orig_len);
	break;
	} else if (len < 0) {
	if (len == -ESTRPIPE && rxm->accum_len) {
	len = -ENODATA;
	strp->rx_unrecov_intr = 1;
	} else {
	strp->rx_interrupted = 1;
	}
	strp_parser_err(strp, len, desc);
	break;
	} else if (len > strp->sk->sk_rcvbuf) {
	/* Message length exceeds maximum allowed */
	STRP_STATS_INCR(strp->stats.rx_msg_too_big);
	strp_parser_err(strp, -EMSGSIZE, desc);
	break;
	} else if (len <= (ssize_t)head->len -
	skb->len - rxm->strp.offset) {
	/* Length must be into new skb (and also
	* greater than zero)
	*/
	STRP_STATS_INCR(strp->stats.rx_bad_hdr_len);
	strp_parser_err(strp, -EPROTO, desc);
	break;
	}

	rxm->strp.full_len = len;
	}

	extra = (ssize_t)(rxm->accum_len + cand_len) -
	rxm->strp.full_len;

	if (extra < 0) {
	/* Message not complete yet. */
	if (rxm->strp.full_len - rxm->accum_len >
	strp_peek_len(strp)) {
	/* Don't have the whole messages in the socket
	* buffer. Set strp->rx_need_bytes to wait for
	* the rest of the message. Also, set "early
	* eaten" since we've already buffered the skb
	* but don't consume yet per strp_read_sock.
	*/

	if (!rxm->accum_len) {
	/* Start RX timer for new message */
	strp_start_rx_timer(strp);
	}

	rxm->accum_len += cand_len;
	strp->rx_need_bytes = rxm->strp.full_len -
	rxm->accum_len;
	rxm->early_eaten = cand_len;
	STRP_STATS_ADD(strp->stats.rx_bytes, cand_len);
	desc->count = 0; /* Stop reading socket */
	break;
	}
	rxm->accum_len += cand_len;
	eaten += cand_len;
	WARN_ON(eaten != orig_len);
	break;
	}

	/* Positive extra indicates ore bytes than needed for the
	* message
	*/

	WARN_ON(extra > cand_len);

	eaten += (cand_len - extra);

	/* Hurray, we have a new message! */
	del_timer(&strp->rx_msg_timer);
	strp->rx_skb_head = NULL;
	strp->rx_need_bytes = 0;
	STRP_STATS_INCR(strp->stats.rx_msgs);

	/* Give skb to upper layer */
	strp->cb.rcv_msg(strp, head);

	if (unlikely(strp->rx_paused)) {
	/* Upper layer paused strp */
	break;
	}
	}

	if (cloned_orig)
	kfree_skb(orig_skb);

	STRP_STATS_ADD(strp->stats.rx_bytes, eaten);

	return eaten;
	}

	static int default_read_sock_done(struct strparser *strp, int err)
	{
	return err;
	}

	/* Called with lock held on lower socket */
	static int strp_read_sock(struct strparser *strp)
	{
	struct socket *sock = strp->sk->sk_socket;
	read_descriptor_t desc;

	desc.arg.data = strp;
	desc.error = 0;
	desc.count = 1; /* give more than one skb per call */

	/* sk should be locked here, so okay to do read_sock */
	sock->ops->read_sock(strp->sk, &desc, strp_recv);

	desc.error = strp->cb.read_sock_done(strp, desc.error);

	return desc.error;
	}

	/* Lower sock lock held */
	void strp_data_ready(struct strparser *strp)
	{
	if (unlikely(strp->rx_stopped))
	return;

	/* This check is needed to synchronize with do_strp_rx_work.
	* do_strp_rx_work acquires a process lock (lock_sock) whereas
	* the lock held here is bh_lock_sock. The two locks can be
	* held by different threads at the same time, but bh_lock_sock
	* allows a thread in BH context to safely check if the process
	* lock is held. In this case, if the lock is held, queue work.
	*/
	if (sock_owned_by_user(strp->sk)) {
	queue_work(strp_wq, &strp->rx_work);
	return;
	}

	if (strp->rx_paused)
	return;

	if (strp->rx_need_bytes) {
	if (strp_peek_len(strp) < strp->rx_need_bytes)
	return;
	}

	if (strp_read_sock(strp) == -ENOMEM)
	queue_work(strp_wq, &strp->rx_work);
	}
	EXPORT_SYMBOL_GPL(strp_data_ready);

	static void do_strp_rx_work(struct strparser *strp)
	{
	read_descriptor_t rd_desc;
	struct sock *csk = strp->sk;

	/* We need the read lock to synchronize with strp_data_ready. We
	* need the socket lock for calling strp_read_sock.
	*/
	lock_sock(csk);

	if (unlikely(strp->rx_stopped))
	goto out;

	if (strp->rx_paused)
	goto out;

	rd_desc.arg.data = strp;

	if (strp_read_sock(strp) == -ENOMEM)
	queue_work(strp_wq, &strp->rx_work);

	out:
	release_sock(csk);
	}

	static void strp_rx_work(struct work_struct *w)
	{
	do_strp_rx_work(container_of(w, struct strparser, rx_work));
	}

	static void strp_rx_msg_timeout(unsigned long arg)
	{
	struct strparser strp = (struct strparser )arg;

	/* Message assembly timed out */
	STRP_STATS_INCR(strp->stats.rx_msg_timeouts);
	lock_sock(strp->sk);
	strp->cb.abort_parser(strp, -ETIMEDOUT);
	release_sock(strp->sk);
	}

	int strp_init(struct strparser strp, struct sock csk,
	struct strp_callbacks *cb)
	{
	struct socket *sock = csk->sk_socket;

	if (!cb \|\| !cb->rcv_msg \|\| !cb->parse_msg)
	return -EINVAL;

	if (!sock->ops->read_sock \|\| !sock->ops->peek_len)
	return -EAFNOSUPPORT;

	memset(strp, 0, sizeof(*strp));

	strp->sk = csk;

	setup_timer(&strp->rx_msg_timer, strp_rx_msg_timeout,
	(unsigned long)strp);

	INIT_WORK(&strp->rx_work, strp_rx_work);

	strp->cb.rcv_msg = cb->rcv_msg;
	strp->cb.parse_msg = cb->parse_msg;
	strp->cb.read_sock_done = cb->read_sock_done ? : default_read_sock_done;
	strp->cb.abort_parser = cb->abort_parser ? : strp_abort_rx_strp;

	return 0;
	}
	EXPORT_SYMBOL_GPL(strp_init);

	void strp_unpause(struct strparser *strp)
	{
	strp->rx_paused = 0;

	/* Sync setting rx_paused with RX work */
	smp_mb();

	queue_work(strp_wq, &strp->rx_work);
	}
	EXPORT_SYMBOL_GPL(strp_unpause);

	/* strp must already be stopped so that strp_recv will no longer be called.
	* Note that strp_done is not called with the lower socket held.
	*/
	void strp_done(struct strparser *strp)
	{
	WARN_ON(!strp->rx_stopped);

	del_timer_sync(&strp->rx_msg_timer);
	cancel_work_sync(&strp->rx_work);

	if (strp->rx_skb_head) {
	kfree_skb(strp->rx_skb_head);
	strp->rx_skb_head = NULL;
	}
	}
	EXPORT_SYMBOL_GPL(strp_done);

	void strp_stop(struct strparser *strp)
	{
	strp->rx_stopped = 1;
	}
	EXPORT_SYMBOL_GPL(strp_stop);

	void strp_check_rcv(struct strparser *strp)
	{
	queue_work(strp_wq, &strp->rx_work);
	}
	EXPORT_SYMBOL_GPL(strp_check_rcv);

	static int __init strp_mod_init(void)
	{
	strp_wq = create_singlethread_workqueue("kstrp");

	return 0;
	}

	static void __exit strp_mod_exit(void)
	{
	destroy_workqueue(strp_wq);
	}
	module_init(strp_mod_init);
	module_exit(strp_mod_exit);
	MODULE_LICENSE("GPL");