Edit File: request_sock.h
/* * 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)(struct sock *sk, struct request_sock *req); }; extern 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; struct request_sock *dl_next; 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; unsigned long expires; 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 request_sock *req = kmem_cache_alloc(ops->slab, GFP_ATOMIC); if (req != NULL) req->rsk_ops = ops; return req; } static inline void __reqsk_free(struct request_sock *req) { kmem_cache_free(req->rsk_ops->slab, req); } static inline void reqsk_free(struct request_sock *req) { req->rsk_ops->destructor(req); __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 { u8 max_qlen_log; u8 synflood_warned; /* 2 bytes hole, try to use */ int qlen; int qlen_young; int clock_hand; 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). * * This lock is acquired in read mode only from listening_get_next() seq_file * op and it's acquired in write mode _only_ from code that is actively * changing rskq_accept_head. All readers that are holding the master sock lock * don't need to grab this lock in read mode too as rskq_accept_head. writes * are always protected from the main sock lock. */ struct request_sock_queue { struct request_sock *rskq_accept_head; struct request_sock *rskq_accept_tail; rwlock_t syn_wait_lock; u8 rskq_defer_accept; /* 3 bytes hole, try to pack */ 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. */ }; extern int reqsk_queue_alloc(struct request_sock_queue *queue, unsigned int nr_table_entries); extern void __reqsk_queue_destroy(struct request_sock_queue *queue); extern void reqsk_queue_destroy(struct request_sock_queue *queue); extern 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_unlink(struct request_sock_queue *queue, struct request_sock *req, struct request_sock **prev_req) { write_lock(&queue->syn_wait_lock); *prev_req = req->dl_next; write_unlock(&queue->syn_wait_lock); } 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 int reqsk_queue_removed(struct request_sock_queue *queue, struct request_sock *req) { struct listen_sock *lopt = queue->listen_opt; if (req->num_timeout == 0) --lopt->qlen_young; return --lopt->qlen; } static inline int reqsk_queue_added(struct request_sock_queue *queue) { struct listen_sock *lopt = queue->listen_opt; const int prev_qlen = lopt->qlen; lopt->qlen_young++; lopt->qlen++; return prev_qlen; } static inline int reqsk_queue_len(const struct request_sock_queue *queue) { return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0; } static inline int reqsk_queue_len_young(const struct request_sock_queue *queue) { return queue->listen_opt->qlen_young; } static inline int reqsk_queue_is_full(const struct request_sock_queue *queue) { return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log; } static inline void reqsk_queue_hash_req(struct request_sock_queue *queue, u32 hash, struct request_sock *req, unsigned long timeout) { struct listen_sock *lopt = queue->listen_opt; req->expires = jiffies + timeout; req->num_retrans = 0; req->num_timeout = 0; req->sk = NULL; req->dl_next = lopt->syn_table[hash]; write_lock(&queue->syn_wait_lock); lopt->syn_table[hash] = req; write_unlock(&queue->syn_wait_lock); } #endif /* _REQUEST_SOCK_H */