/* * 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				*saved_syn;	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;		req->saved_syn = NULL;		/* 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);	kfree(req->saved_syn);	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 */