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550 lines
13 KiB
550 lines
13 KiB
// 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 <[email protected]> |
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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_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; |
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} |
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} |
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EXPORT_SYMBOL_GPL(strp_done); |
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void strp_stop(struct strparser *strp) |
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{ |
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strp->stopped = 1; |
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} |
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EXPORT_SYMBOL_GPL(strp_stop); |
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void strp_check_rcv(struct strparser *strp) |
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{ |
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queue_work(strp_wq, &strp->work); |
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} |
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EXPORT_SYMBOL_GPL(strp_check_rcv); |
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static int __init strp_dev_init(void) |
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{ |
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strp_wq = create_singlethread_workqueue("kstrp"); |
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if (unlikely(!strp_wq)) |
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return -ENOMEM; |
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return 0; |
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} |
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device_initcall(strp_dev_init);
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