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/* * 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_msg {	/* Internal cb structure. struct strp_msg must be first for passing	 * to upper layer.	 */	struct strp_msg strp;	int accum_len;}; static inline struct _strp_msg *_strp_msg(struct sk_buff *skb){	return (struct _strp_msg *)((void *)skb->cb +		offsetof(struct qdisc_skb_cb, data));} /* Lower lock held */static void strp_abort_strp(struct strparser *strp, int err){	/* Unrecoverable error in receive */ 	cancel_delayed_work(&strp->msg_timer_work); 	if (strp->stopped)		return; 	strp->stopped = 1; 	if (strp->sk) {		struct sock *sk = strp->sk; 		/* Report an error on the lower socket */		sk->sk_err = -err;		sk->sk_error_report(sk);	}} static void strp_start_timer(struct strparser *strp, long timeo){	if (timeo && timeo != LONG_MAX)		mod_delayed_work(strp_wq, &strp->msg_timer_work, timeo);} /* Lower lock held */static void strp_parser_err(struct strparser *strp, int err,			    read_descriptor_t *desc){	desc->error = err;	kfree_skb(strp->skb_head);	strp->skb_head = NULL;	strp->cb.abort_parser(strp, err);} static inline int strp_peek_len(struct strparser *strp){	if (strp->sk) {		struct socket *sock = strp->sk->sk_socket; 		return sock->ops->peek_len(sock);	} 	/* If we don't have an associated socket there's nothing to peek.	 * Return int max to avoid stopping the strparser.	 */ 	return INT_MAX;} /* 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,		       size_t max_msg_size, long timeo){	struct strparser *strp = (struct strparser *)desc->arg.data;	struct _strp_msg *stm;	struct sk_buff *head, *skb;	size_t eaten = 0, cand_len;	ssize_t extra;	int err;	bool cloned_orig = false; 	if (strp->paused)		return 0; 	head = strp->skb_head;	if (head) {		/* Message already in progress */		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.mem_fail);				desc->error = -ENOMEM;				return 0;			}			if (!pskb_pull(orig_skb, orig_offset)) {				STRP_STATS_INCR(strp->stats.mem_fail);				kfree_skb(orig_skb);				desc->error = -ENOMEM;				return 0;			}			cloned_orig = true;			orig_offset = 0;		} 		if (!strp->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.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.mem_fail);					desc->error = -ENOMEM;					return 0;				}				skb->len = head->len;				skb->data_len = head->len;				skb->truesize = head->truesize;				*_strp_msg(skb) = *_strp_msg(head);				strp->skb_nextp = &head->next;				skb_shinfo(skb)->frag_list = head;				strp->skb_head = skb;				head = skb;			} else {				strp->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.mem_fail);			desc->error = -ENOMEM;			break;		} 		cand_len = orig_len - eaten; 		head = strp->skb_head;		if (!head) {			head = skb;			strp->skb_head = head;			/* Will set skb_nextp on next packet if needed */			strp->skb_nextp = NULL;			stm = _strp_msg(head);			memset(stm, 0, sizeof(*stm));			stm->strp.offset = orig_offset + eaten;		} else {			/* Unclone if we are appending to an skb that we			 * already share a frag_list with.			 */			if (skb_has_frag_list(skb)) {				err = skb_unclone(skb, GFP_ATOMIC);				if (err) {					STRP_STATS_INCR(strp->stats.mem_fail);					desc->error = err;					break;				}			} 			stm = _strp_msg(head);			*strp->skb_nextp = skb;			strp->skb_nextp = &skb->next;			head->data_len += skb->len;			head->len += skb->len;			head->truesize += skb->truesize;		} 		if (!stm->strp.full_len) {			ssize_t len; 			len = (*strp->cb.parse_msg)(strp, head); 			if (!len) {				/* Need more header to determine length */				if (!stm->accum_len) {					/* Start RX timer for new message */					strp_start_timer(strp, timeo);				}				stm->accum_len += cand_len;				eaten += cand_len;				STRP_STATS_INCR(strp->stats.need_more_hdr);				WARN_ON(eaten != orig_len);				break;			} else if (len < 0) {				if (len == -ESTRPIPE && stm->accum_len) {					len = -ENODATA;					strp->unrecov_intr = 1;				} else {					strp->interrupted = 1;				}				strp_parser_err(strp, len, desc);				break;			} else if (len > max_msg_size) {				/* Message length exceeds maximum allowed */				STRP_STATS_INCR(strp->stats.msg_too_big);				strp_parser_err(strp, -EMSGSIZE, desc);				break;			} else if (len <= (ssize_t)head->len -					  skb->len - stm->strp.offset) {				/* Length must be into new skb (and also				 * greater than zero)				 */				STRP_STATS_INCR(strp->stats.bad_hdr_len);				strp_parser_err(strp, -EPROTO, desc);				break;			} 			stm->strp.full_len = len;		} 		extra = (ssize_t)(stm->accum_len + cand_len) -			stm->strp.full_len; 		if (extra < 0) {			/* Message not complete yet. */			if (stm->strp.full_len - stm->accum_len >			    strp_peek_len(strp)) {				/* Don't have the whole message in the socket				 * buffer. Set strp->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 (!stm->accum_len) {					/* Start RX timer for new message */					strp_start_timer(strp, timeo);				} 				stm->accum_len += cand_len;				eaten += cand_len;				strp->need_bytes = stm->strp.full_len -						       stm->accum_len;				STRP_STATS_ADD(strp->stats.bytes, cand_len);				desc->count = 0; /* Stop reading socket */				break;			}			stm->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! */		cancel_delayed_work(&strp->msg_timer_work);		strp->skb_head = NULL;		strp->need_bytes = 0;		STRP_STATS_INCR(strp->stats.msgs); 		/* Give skb to upper layer */		strp->cb.rcv_msg(strp, head); 		if (unlikely(strp->paused)) {			/* Upper layer paused strp */			break;		}	} 	if (cloned_orig)		kfree_skb(orig_skb); 	STRP_STATS_ADD(strp->stats.bytes, eaten); 	return eaten;} int strp_process(struct strparser *strp, struct sk_buff *orig_skb,		 unsigned int orig_offset, size_t orig_len,		 size_t max_msg_size, long timeo){	read_descriptor_t desc; /* Dummy arg to strp_recv */ 	desc.arg.data = strp; 	return __strp_recv(&desc, orig_skb, orig_offset, orig_len,			   max_msg_size, timeo);}EXPORT_SYMBOL_GPL(strp_process); 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; 	return __strp_recv(desc, orig_skb, orig_offset, orig_len,			   strp->sk->sk_rcvbuf, strp->sk->sk_rcvtimeo);} 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; 	if (unlikely(!sock || !sock->ops || !sock->ops->read_sock))		return -EBUSY; 	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->stopped) || strp->paused)		return; 	/* This check is needed to synchronize with do_strp_work.	 * do_strp_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_nocheck(strp->sk)) {		queue_work(strp_wq, &strp->work);		return;	} 	if (strp->need_bytes) {		if (strp_peek_len(strp) < strp->need_bytes)			return;	} 	if (strp_read_sock(strp) == -ENOMEM)		queue_work(strp_wq, &strp->work);}EXPORT_SYMBOL_GPL(strp_data_ready); static void do_strp_work(struct strparser *strp){	/* We need the read lock to synchronize with strp_data_ready. We	 * need the socket lock for calling strp_read_sock.	 */	strp->cb.lock(strp); 	if (unlikely(strp->stopped))		goto out; 	if (strp->paused)		goto out; 	if (strp_read_sock(strp) == -ENOMEM)		queue_work(strp_wq, &strp->work); out:	strp->cb.unlock(strp);} static void strp_work(struct work_struct *w){	do_strp_work(container_of(w, struct strparser, work));} static void strp_msg_timeout(struct work_struct *w){	struct strparser *strp = container_of(w, struct strparser,					      msg_timer_work.work); 	/* Message assembly timed out */	STRP_STATS_INCR(strp->stats.msg_timeouts);	strp->cb.lock(strp);	strp->cb.abort_parser(strp, -ETIMEDOUT);	strp->cb.unlock(strp);} static void strp_sock_lock(struct strparser *strp){	lock_sock(strp->sk);} static void strp_sock_unlock(struct strparser *strp){	release_sock(strp->sk);} int strp_init(struct strparser *strp, struct sock *sk,	      const struct strp_callbacks *cb){ 	if (!cb || !cb->rcv_msg || !cb->parse_msg)		return -EINVAL; 	/* The sk (sock) arg determines the mode of the stream parser.	 *	 * If the sock is set then the strparser is in receive callback mode.	 * The upper layer calls strp_data_ready to kick receive processing	 * and strparser calls the read_sock function on the socket to	 * get packets.	 *	 * If the sock is not set then the strparser is in general mode.	 * The upper layer calls strp_process for each skb to be parsed.	 */ 	if (!sk) {		if (!cb->lock || !cb->unlock)			return -EINVAL;	} 	memset(strp, 0, sizeof(*strp)); 	strp->sk = sk; 	strp->cb.lock = cb->lock ? : strp_sock_lock;	strp->cb.unlock = cb->unlock ? : strp_sock_unlock;	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_strp; 	INIT_DELAYED_WORK(&strp->msg_timer_work, strp_msg_timeout);	INIT_WORK(&strp->work, strp_work); 	return 0;}EXPORT_SYMBOL_GPL(strp_init); /* Sock process lock held (lock_sock) */void __strp_unpause(struct strparser *strp){	strp->paused = 0; 	if (strp->need_bytes) {

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