Initial import

1 files changed, 294 insertions, 0 deletions

diff --git a/include/net/request_sock.h b/include/net/request_sock.h
new file mode 100644
index 000000000..9f4265ce8
--- /dev/null
+++ b/include/net/request_sock.h
@@ -0,0 +1,294 @@
+/*
+ * NET		Generic infrastructure for Network protocols.
+ *
+ *		Definitions for request_sock 
+ *
+ * Authors:	Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ * 		From code originally in include/net/tcp.h
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ */
+#ifndef _REQUEST_SOCK_H
+#define _REQUEST_SOCK_H
+
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/bug.h>
+
+#include <net/sock.h>
+
+struct request_sock;
+struct sk_buff;
+struct dst_entry;
+struct proto;
+
+struct request_sock_ops {
+	int		family;
+	int		obj_size;
+	struct kmem_cache	*slab;
+	char		*slab_name;
+	int		(*rtx_syn_ack)(struct sock *sk,
+				       struct request_sock *req);
+	void		(*send_ack)(struct sock *sk, struct sk_buff *skb,
+				    struct request_sock *req);
+	void		(*send_reset)(struct sock *sk,
+				      struct sk_buff *skb);
+	void		(*destructor)(struct request_sock *req);
+	void		(*syn_ack_timeout)(const struct request_sock *req);
+};
+
+int inet_rtx_syn_ack(struct sock *parent, struct request_sock *req);
+
+/* struct request_sock - mini sock to represent a connection request
+ */
+struct request_sock {
+	struct sock_common		__req_common;
+#define rsk_refcnt			__req_common.skc_refcnt
+#define rsk_hash			__req_common.skc_hash
+
+	struct request_sock		*dl_next;
+	struct sock			*rsk_listener;
+	u16				mss;
+	u8				num_retrans; /* number of retransmits */
+	u8				cookie_ts:1; /* syncookie: encode tcpopts in timestamp */
+	u8				num_timeout:7; /* number of timeouts */
+	/* The following two fields can be easily recomputed I think -AK */
+	u32				window_clamp; /* window clamp at creation time */
+	u32				rcv_wnd;	  /* rcv_wnd offered first time */
+	u32				ts_recent;
+	struct timer_list		rsk_timer;
+	const struct request_sock_ops	*rsk_ops;
+	struct sock			*sk;
+	u32				secid;
+	u32				peer_secid;
+};
+
+static inline struct request_sock *
+reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener)
+{
+	struct request_sock *req = kmem_cache_alloc(ops->slab, GFP_ATOMIC);
+
+	if (req) {
+		req->rsk_ops = ops;
+		sock_hold(sk_listener);
+		req->rsk_listener = sk_listener;
+
+		/* Following is temporary. It is coupled with debugging
+		 * helpers in reqsk_put() & reqsk_free()
+		 */
+		atomic_set(&req->rsk_refcnt, 0);
+	}
+	return req;
+}
+
+static inline struct request_sock *inet_reqsk(struct sock *sk)
+{
+	return (struct request_sock *)sk;
+}
+
+static inline struct sock *req_to_sk(struct request_sock *req)
+{
+	return (struct sock *)req;
+}
+
+static inline void reqsk_free(struct request_sock *req)
+{
+	/* temporary debugging */
+	WARN_ON_ONCE(atomic_read(&req->rsk_refcnt) != 0);
+
+	req->rsk_ops->destructor(req);
+	if (req->rsk_listener)
+		sock_put(req->rsk_listener);
+	kmem_cache_free(req->rsk_ops->slab, req);
+}
+
+static inline void reqsk_put(struct request_sock *req)
+{
+	if (atomic_dec_and_test(&req->rsk_refcnt))
+		reqsk_free(req);
+}
+
+extern int sysctl_max_syn_backlog;
+
+/** struct listen_sock - listen state
+ *
+ * @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs
+ */
+struct listen_sock {
+	int			qlen_inc; /* protected by listener lock */
+	int			young_inc;/* protected by listener lock */
+
+	/* following fields can be updated by timer */
+	atomic_t		qlen_dec; /* qlen = qlen_inc - qlen_dec */
+	atomic_t		young_dec;
+
+	u8			max_qlen_log ____cacheline_aligned_in_smp;
+	u8			synflood_warned;
+	/* 2 bytes hole, try to use */
+	u32			hash_rnd;
+	u32			nr_table_entries;
+	struct request_sock	*syn_table[0];
+};
+
+/*
+ * For a TCP Fast Open listener -
+ *	lock - protects the access to all the reqsk, which is co-owned by
+ *		the listener and the child socket.
+ *	qlen - pending TFO requests (still in TCP_SYN_RECV).
+ *	max_qlen - max TFO reqs allowed before TFO is disabled.
+ *
+ *	XXX (TFO) - ideally these fields can be made as part of "listen_sock"
+ *	structure above. But there is some implementation difficulty due to
+ *	listen_sock being part of request_sock_queue hence will be freed when
+ *	a listener is stopped. But TFO related fields may continue to be
+ *	accessed even after a listener is closed, until its sk_refcnt drops
+ *	to 0 implying no more outstanding TFO reqs. One solution is to keep
+ *	listen_opt around until	sk_refcnt drops to 0. But there is some other
+ *	complexity that needs to be resolved. E.g., a listener can be disabled
+ *	temporarily through shutdown()->tcp_disconnect(), and re-enabled later.
+ */
+struct fastopen_queue {
+	struct request_sock	*rskq_rst_head; /* Keep track of past TFO */
+	struct request_sock	*rskq_rst_tail; /* requests that caused RST.
+						 * This is part of the defense
+						 * against spoofing attack.
+						 */
+	spinlock_t	lock;
+	int		qlen;		/* # of pending (TCP_SYN_RECV) reqs */
+	int		max_qlen;	/* != 0 iff TFO is currently enabled */
+};
+
+/** struct request_sock_queue - queue of request_socks
+ *
+ * @rskq_accept_head - FIFO head of established children
+ * @rskq_accept_tail - FIFO tail of established children
+ * @rskq_defer_accept - User waits for some data after accept()
+ * @syn_wait_lock - serializer
+ *
+ * %syn_wait_lock is necessary only to avoid proc interface having to grab the main
+ * lock sock while browsing the listening hash (otherwise it's deadlock prone).
+ *
+ */
+struct request_sock_queue {
+	struct request_sock	*rskq_accept_head;
+	struct request_sock	*rskq_accept_tail;
+	u8			rskq_defer_accept;
+	struct listen_sock	*listen_opt;
+	struct fastopen_queue	*fastopenq; /* This is non-NULL iff TFO has been
+					     * enabled on this listener. Check
+					     * max_qlen != 0 in fastopen_queue
+					     * to determine if TFO is enabled
+					     * right at this moment.
+					     */
+
+	/* temporary alignment, our goal is to get rid of this lock */
+	spinlock_t		syn_wait_lock ____cacheline_aligned_in_smp;
+};
+
+int reqsk_queue_alloc(struct request_sock_queue *queue,
+		      unsigned int nr_table_entries);
+
+void __reqsk_queue_destroy(struct request_sock_queue *queue);
+void reqsk_queue_destroy(struct request_sock_queue *queue);
+void reqsk_fastopen_remove(struct sock *sk, struct request_sock *req,
+			   bool reset);
+
+static inline struct request_sock *
+	reqsk_queue_yank_acceptq(struct request_sock_queue *queue)
+{
+	struct request_sock *req = queue->rskq_accept_head;
+
+	queue->rskq_accept_head = NULL;
+	return req;
+}
+
+static inline int reqsk_queue_empty(struct request_sock_queue *queue)
+{
+	return queue->rskq_accept_head == NULL;
+}
+
+static inline void reqsk_queue_add(struct request_sock_queue *queue,
+				   struct request_sock *req,
+				   struct sock *parent,
+				   struct sock *child)
+{
+	req->sk = child;
+	sk_acceptq_added(parent);
+
+	if (queue->rskq_accept_head == NULL)
+		queue->rskq_accept_head = req;
+	else
+		queue->rskq_accept_tail->dl_next = req;
+
+	queue->rskq_accept_tail = req;
+	req->dl_next = NULL;
+}
+
+static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
+{
+	struct request_sock *req = queue->rskq_accept_head;
+
+	WARN_ON(req == NULL);
+
+	queue->rskq_accept_head = req->dl_next;
+	if (queue->rskq_accept_head == NULL)
+		queue->rskq_accept_tail = NULL;
+
+	return req;
+}
+
+static inline void reqsk_queue_removed(struct request_sock_queue *queue,
+				       const struct request_sock *req)
+{
+	struct listen_sock *lopt = queue->listen_opt;
+
+	if (req->num_timeout == 0)
+		atomic_inc(&lopt->young_dec);
+	atomic_inc(&lopt->qlen_dec);
+}
+
+static inline void reqsk_queue_added(struct request_sock_queue *queue)
+{
+	struct listen_sock *lopt = queue->listen_opt;
+
+	lopt->young_inc++;
+	lopt->qlen_inc++;
+}
+
+static inline int listen_sock_qlen(const struct listen_sock *lopt)
+{
+	return lopt->qlen_inc - atomic_read(&lopt->qlen_dec);
+}
+
+static inline int listen_sock_young(const struct listen_sock *lopt)
+{
+	return lopt->young_inc - atomic_read(&lopt->young_dec);
+}
+
+static inline int reqsk_queue_len(const struct request_sock_queue *queue)
+{
+	const struct listen_sock *lopt = queue->listen_opt;
+
+	return lopt ? listen_sock_qlen(lopt) : 0;
+}
+
+static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
+{
+	return listen_sock_young(queue->listen_opt);
+}
+
+static inline int reqsk_queue_is_full(const struct request_sock_queue *queue)
+{
+	return reqsk_queue_len(queue) >> queue->listen_opt->max_qlen_log;
+}
+
+void reqsk_queue_hash_req(struct request_sock_queue *queue,
+			  u32 hash, struct request_sock *req,
+			  unsigned long timeout);
+
+#endif /* _REQUEST_SOCK_H */