1 files changed, 561 insertions, 0 deletions

diff --git a/net/strparser/strparser.c b/net/strparser/strparser.c
new file mode 100644
index 000000000..0f4e42792
--- /dev/null
+++ b/net/strparser/strparser.c
@@ -0,0 +1,561 @@
+/*
+ * 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) {
+		if (strp_peek_len(strp) < strp->need_bytes)
+			return;
+	}
+	strp_read_sock(strp);
+}
+EXPORT_SYMBOL_GPL(__strp_unpause);
+
+void strp_unpause(struct strparser *strp)
+{
+	strp->paused = 0;
+
+	/* Sync setting paused with RX work */
+	smp_mb();
+
+	queue_work(strp_wq, &strp->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->stopped);
+
+	cancel_delayed_work_sync(&strp->msg_timer_work);
+	cancel_work_sync(&strp->work);
+
+	if (strp->skb_head) {
+		kfree_skb(strp->skb_head);
+		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_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");