mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-21 16:29:59 +00:00
550 lines
13 KiB
C
550 lines
13 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Stream Parser
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*
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* Copyright (c) 2016 Tom Herbert <tom@herbertland.com>
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*/
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#include <linux/bpf.h>
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#include <linux/errno.h>
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#include <linux/errqueue.h>
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#include <linux/file.h>
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#include <linux/in.h>
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#include <linux/kernel.h>
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#include <linux/export.h>
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#include <linux/init.h>
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#include <linux/net.h>
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#include <linux/netdevice.h>
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#include <linux/poll.h>
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#include <linux/rculist.h>
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#include <linux/skbuff.h>
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#include <linux/socket.h>
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#include <linux/uaccess.h>
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#include <linux/workqueue.h>
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#include <net/strparser.h>
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#include <net/netns/generic.h>
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#include <net/sock.h>
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static struct workqueue_struct *strp_wq;
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struct _strp_msg {
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/* Internal cb structure. struct strp_msg must be first for passing
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* to upper layer.
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*/
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struct strp_msg strp;
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int accum_len;
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};
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static inline struct _strp_msg *_strp_msg(struct sk_buff *skb)
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{
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return (struct _strp_msg *)((void *)skb->cb +
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offsetof(struct qdisc_skb_cb, data));
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}
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/* Lower lock held */
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static void strp_abort_strp(struct strparser *strp, int err)
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{
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/* Unrecoverable error in receive */
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cancel_delayed_work(&strp->msg_timer_work);
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if (strp->stopped)
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return;
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strp->stopped = 1;
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if (strp->sk) {
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struct sock *sk = strp->sk;
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/* Report an error on the lower socket */
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sk->sk_err = -err;
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sk->sk_error_report(sk);
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}
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}
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static void strp_start_timer(struct strparser *strp, long timeo)
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{
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if (timeo && timeo != LONG_MAX)
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mod_delayed_work(strp_wq, &strp->msg_timer_work, timeo);
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}
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/* Lower lock held */
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static void strp_parser_err(struct strparser *strp, int err,
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read_descriptor_t *desc)
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{
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desc->error = err;
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kfree_skb(strp->skb_head);
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strp->skb_head = NULL;
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strp->cb.abort_parser(strp, err);
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}
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static inline int strp_peek_len(struct strparser *strp)
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{
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if (strp->sk) {
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struct socket *sock = strp->sk->sk_socket;
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return sock->ops->peek_len(sock);
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}
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/* If we don't have an associated socket there's nothing to peek.
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* Return int max to avoid stopping the strparser.
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*/
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return INT_MAX;
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}
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/* Lower socket lock held */
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static int __strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
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unsigned int orig_offset, size_t orig_len,
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size_t max_msg_size, long timeo)
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{
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struct strparser *strp = (struct strparser *)desc->arg.data;
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struct _strp_msg *stm;
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struct sk_buff *head, *skb;
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size_t eaten = 0, cand_len;
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ssize_t extra;
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int err;
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bool cloned_orig = false;
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if (strp->paused)
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return 0;
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head = strp->skb_head;
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if (head) {
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/* Message already in progress */
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if (unlikely(orig_offset)) {
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/* Getting data with a non-zero offset when a message is
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* in progress is not expected. If it does happen, we
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* need to clone and pull since we can't deal with
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* offsets in the skbs for a message expect in the head.
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*/
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orig_skb = skb_clone(orig_skb, GFP_ATOMIC);
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if (!orig_skb) {
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STRP_STATS_INCR(strp->stats.mem_fail);
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desc->error = -ENOMEM;
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return 0;
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}
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if (!pskb_pull(orig_skb, orig_offset)) {
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STRP_STATS_INCR(strp->stats.mem_fail);
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kfree_skb(orig_skb);
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desc->error = -ENOMEM;
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return 0;
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}
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cloned_orig = true;
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orig_offset = 0;
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}
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if (!strp->skb_nextp) {
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/* We are going to append to the frags_list of head.
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* Need to unshare the frag_list.
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*/
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err = skb_unclone(head, GFP_ATOMIC);
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if (err) {
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STRP_STATS_INCR(strp->stats.mem_fail);
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desc->error = err;
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return 0;
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}
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if (unlikely(skb_shinfo(head)->frag_list)) {
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/* We can't append to an sk_buff that already
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* has a frag_list. We create a new head, point
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* the frag_list of that to the old head, and
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* then are able to use the old head->next for
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* appending to the message.
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*/
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if (WARN_ON(head->next)) {
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desc->error = -EINVAL;
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return 0;
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}
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skb = alloc_skb_for_msg(head);
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if (!skb) {
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STRP_STATS_INCR(strp->stats.mem_fail);
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desc->error = -ENOMEM;
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return 0;
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}
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strp->skb_nextp = &head->next;
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strp->skb_head = skb;
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head = skb;
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} else {
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strp->skb_nextp =
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&skb_shinfo(head)->frag_list;
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}
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}
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}
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while (eaten < orig_len) {
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/* Always clone since we will consume something */
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skb = skb_clone(orig_skb, GFP_ATOMIC);
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if (!skb) {
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STRP_STATS_INCR(strp->stats.mem_fail);
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desc->error = -ENOMEM;
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break;
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}
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cand_len = orig_len - eaten;
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head = strp->skb_head;
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if (!head) {
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head = skb;
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strp->skb_head = head;
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/* Will set skb_nextp on next packet if needed */
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strp->skb_nextp = NULL;
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stm = _strp_msg(head);
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memset(stm, 0, sizeof(*stm));
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stm->strp.offset = orig_offset + eaten;
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} else {
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/* Unclone if we are appending to an skb that we
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* already share a frag_list with.
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*/
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if (skb_has_frag_list(skb)) {
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err = skb_unclone(skb, GFP_ATOMIC);
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if (err) {
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STRP_STATS_INCR(strp->stats.mem_fail);
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desc->error = err;
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break;
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}
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}
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stm = _strp_msg(head);
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*strp->skb_nextp = skb;
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strp->skb_nextp = &skb->next;
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head->data_len += skb->len;
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head->len += skb->len;
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head->truesize += skb->truesize;
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}
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if (!stm->strp.full_len) {
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ssize_t len;
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len = (*strp->cb.parse_msg)(strp, head);
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if (!len) {
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/* Need more header to determine length */
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if (!stm->accum_len) {
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/* Start RX timer for new message */
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strp_start_timer(strp, timeo);
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}
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stm->accum_len += cand_len;
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eaten += cand_len;
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STRP_STATS_INCR(strp->stats.need_more_hdr);
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WARN_ON(eaten != orig_len);
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break;
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} else if (len < 0) {
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if (len == -ESTRPIPE && stm->accum_len) {
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len = -ENODATA;
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strp->unrecov_intr = 1;
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} else {
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strp->interrupted = 1;
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}
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strp_parser_err(strp, len, desc);
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break;
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} else if (len > max_msg_size) {
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/* Message length exceeds maximum allowed */
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STRP_STATS_INCR(strp->stats.msg_too_big);
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strp_parser_err(strp, -EMSGSIZE, desc);
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break;
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} else if (len <= (ssize_t)head->len -
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skb->len - stm->strp.offset) {
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/* Length must be into new skb (and also
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* greater than zero)
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*/
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STRP_STATS_INCR(strp->stats.bad_hdr_len);
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strp_parser_err(strp, -EPROTO, desc);
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break;
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}
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stm->strp.full_len = len;
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}
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extra = (ssize_t)(stm->accum_len + cand_len) -
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stm->strp.full_len;
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if (extra < 0) {
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/* Message not complete yet. */
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if (stm->strp.full_len - stm->accum_len >
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strp_peek_len(strp)) {
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/* Don't have the whole message in the socket
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* buffer. Set strp->need_bytes to wait for
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* the rest of the message. Also, set "early
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* eaten" since we've already buffered the skb
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* but don't consume yet per strp_read_sock.
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*/
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if (!stm->accum_len) {
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/* Start RX timer for new message */
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strp_start_timer(strp, timeo);
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}
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stm->accum_len += cand_len;
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eaten += cand_len;
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strp->need_bytes = stm->strp.full_len -
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stm->accum_len;
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STRP_STATS_ADD(strp->stats.bytes, cand_len);
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desc->count = 0; /* Stop reading socket */
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break;
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}
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stm->accum_len += cand_len;
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eaten += cand_len;
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WARN_ON(eaten != orig_len);
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break;
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}
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/* Positive extra indicates more bytes than needed for the
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* message
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*/
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WARN_ON(extra > cand_len);
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eaten += (cand_len - extra);
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/* Hurray, we have a new message! */
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cancel_delayed_work(&strp->msg_timer_work);
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strp->skb_head = NULL;
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strp->need_bytes = 0;
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STRP_STATS_INCR(strp->stats.msgs);
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/* Give skb to upper layer */
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strp->cb.rcv_msg(strp, head);
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if (unlikely(strp->paused)) {
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/* Upper layer paused strp */
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break;
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}
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}
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if (cloned_orig)
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kfree_skb(orig_skb);
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STRP_STATS_ADD(strp->stats.bytes, eaten);
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return eaten;
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}
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int strp_process(struct strparser *strp, struct sk_buff *orig_skb,
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unsigned int orig_offset, size_t orig_len,
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size_t max_msg_size, long timeo)
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{
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read_descriptor_t desc; /* Dummy arg to strp_recv */
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desc.arg.data = strp;
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return __strp_recv(&desc, orig_skb, orig_offset, orig_len,
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max_msg_size, timeo);
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}
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EXPORT_SYMBOL_GPL(strp_process);
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static int strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
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unsigned int orig_offset, size_t orig_len)
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{
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struct strparser *strp = (struct strparser *)desc->arg.data;
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return __strp_recv(desc, orig_skb, orig_offset, orig_len,
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strp->sk->sk_rcvbuf, strp->sk->sk_rcvtimeo);
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}
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static int default_read_sock_done(struct strparser *strp, int err)
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{
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return err;
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}
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/* Called with lock held on lower socket */
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static int strp_read_sock(struct strparser *strp)
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{
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struct socket *sock = strp->sk->sk_socket;
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read_descriptor_t desc;
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if (unlikely(!sock || !sock->ops || !sock->ops->read_sock))
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return -EBUSY;
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desc.arg.data = strp;
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desc.error = 0;
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desc.count = 1; /* give more than one skb per call */
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/* sk should be locked here, so okay to do read_sock */
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sock->ops->read_sock(strp->sk, &desc, strp_recv);
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desc.error = strp->cb.read_sock_done(strp, desc.error);
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return desc.error;
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}
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/* Lower sock lock held */
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void strp_data_ready(struct strparser *strp)
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{
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if (unlikely(strp->stopped) || strp->paused)
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return;
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/* This check is needed to synchronize with do_strp_work.
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* do_strp_work acquires a process lock (lock_sock) whereas
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* the lock held here is bh_lock_sock. The two locks can be
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* held by different threads at the same time, but bh_lock_sock
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* allows a thread in BH context to safely check if the process
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* lock is held. In this case, if the lock is held, queue work.
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*/
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if (sock_owned_by_user_nocheck(strp->sk)) {
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queue_work(strp_wq, &strp->work);
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return;
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}
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if (strp->need_bytes) {
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if (strp_peek_len(strp) < strp->need_bytes)
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return;
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}
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if (strp_read_sock(strp) == -ENOMEM)
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queue_work(strp_wq, &strp->work);
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}
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EXPORT_SYMBOL_GPL(strp_data_ready);
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static void do_strp_work(struct strparser *strp)
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{
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/* We need the read lock to synchronize with strp_data_ready. We
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* need the socket lock for calling strp_read_sock.
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*/
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strp->cb.lock(strp);
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if (unlikely(strp->stopped))
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goto out;
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if (strp->paused)
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goto out;
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if (strp_read_sock(strp) == -ENOMEM)
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queue_work(strp_wq, &strp->work);
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out:
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strp->cb.unlock(strp);
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}
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static void strp_work(struct work_struct *w)
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{
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do_strp_work(container_of(w, struct strparser, work));
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}
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static void strp_msg_timeout(struct work_struct *w)
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{
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struct strparser *strp = container_of(w, struct strparser,
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msg_timer_work.work);
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/* Message assembly timed out */
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STRP_STATS_INCR(strp->stats.msg_timeouts);
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strp->cb.lock(strp);
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strp->cb.abort_parser(strp, -ETIMEDOUT);
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strp->cb.unlock(strp);
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}
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static void strp_sock_lock(struct strparser *strp)
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{
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lock_sock(strp->sk);
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}
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static void strp_sock_unlock(struct strparser *strp)
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{
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release_sock(strp->sk);
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}
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int strp_init(struct strparser *strp, struct sock *sk,
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const struct strp_callbacks *cb)
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{
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if (!cb || !cb->rcv_msg || !cb->parse_msg)
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return -EINVAL;
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/* The sk (sock) arg determines the mode of the stream parser.
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*
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* If the sock is set then the strparser is in receive callback mode.
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* The upper layer calls strp_data_ready to kick receive processing
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* and strparser calls the read_sock function on the socket to
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* get packets.
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*
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* If the sock is not set then the strparser is in general mode.
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* The upper layer calls strp_process for each skb to be parsed.
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*/
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if (!sk) {
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if (!cb->lock || !cb->unlock)
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return -EINVAL;
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}
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memset(strp, 0, sizeof(*strp));
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strp->sk = sk;
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strp->cb.lock = cb->lock ? : strp_sock_lock;
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strp->cb.unlock = cb->unlock ? : strp_sock_unlock;
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strp->cb.rcv_msg = cb->rcv_msg;
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strp->cb.parse_msg = cb->parse_msg;
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strp->cb.read_sock_done = cb->read_sock_done ? : default_read_sock_done;
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strp->cb.abort_parser = cb->abort_parser ? : strp_abort_strp;
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INIT_DELAYED_WORK(&strp->msg_timer_work, strp_msg_timeout);
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INIT_WORK(&strp->work, strp_work);
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return 0;
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}
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EXPORT_SYMBOL_GPL(strp_init);
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/* Sock process lock held (lock_sock) */
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void __strp_unpause(struct strparser *strp)
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{
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strp->paused = 0;
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if (strp->need_bytes) {
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if (strp_peek_len(strp) < strp->need_bytes)
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return;
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}
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strp_read_sock(strp);
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}
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EXPORT_SYMBOL_GPL(__strp_unpause);
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void strp_unpause(struct strparser *strp)
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{
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strp->paused = 0;
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/* Sync setting paused with RX work */
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smp_mb();
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queue_work(strp_wq, &strp->work);
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}
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EXPORT_SYMBOL_GPL(strp_unpause);
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/* strp must already be stopped so that strp_recv will no longer be called.
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* Note that strp_done is not called with the lower socket held.
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*/
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void strp_done(struct strparser *strp)
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{
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WARN_ON(!strp->stopped);
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cancel_delayed_work_sync(&strp->msg_timer_work);
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cancel_work_sync(&strp->work);
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if (strp->skb_head) {
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kfree_skb(strp->skb_head);
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strp->skb_head = NULL;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(strp_done);
|
|
|
|
void strp_stop(struct strparser *strp)
|
|
{
|
|
strp->stopped = 1;
|
|
}
|
|
EXPORT_SYMBOL_GPL(strp_stop);
|
|
|
|
void strp_check_rcv(struct strparser *strp)
|
|
{
|
|
queue_work(strp_wq, &strp->work);
|
|
}
|
|
EXPORT_SYMBOL_GPL(strp_check_rcv);
|
|
|
|
static int __init strp_dev_init(void)
|
|
{
|
|
strp_wq = create_singlethread_workqueue("kstrp");
|
|
if (unlikely(!strp_wq))
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
device_initcall(strp_dev_init);
|