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편집 파일: request_sock.h

/* SPDX-License-Identifier: GPL-2.0-or-later */ /* * 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 */ #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 <linux/refcount.h> #include <net/sock.h> #include <net/rstreason.h> struct request_sock; struct sk_buff; struct dst_entry; struct proto; struct request_sock_ops { int family; unsigned int obj_size; struct kmem_cache *slab; char *slab_name; int (*rtx_syn_ack)(const struct sock *sk, struct request_sock *req); void (*send_ack)(const struct sock *sk, struct sk_buff *skb, struct request_sock *req); void (*send_reset)(const struct sock *sk, struct sk_buff *skb, enum sk_rst_reason reason); void (*destructor)(struct request_sock *req); void (*syn_ack_timeout)(const struct request_sock *req); }; int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req); struct saved_syn { u32 mac_hdrlen; u32 network_hdrlen; u32 tcp_hdrlen; u8 data[]; }; /* 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 #define rsk_listener __req_common.skc_listener #define rsk_window_clamp __req_common.skc_window_clamp #define rsk_rcv_wnd __req_common.skc_rcv_wnd struct request_sock *dl_next; u16 mss; u8 num_retrans; /* number of retransmits */ u8 syncookie:1; /* syncookie: encode tcpopts in timestamp */ u8 num_timeout:7; /* number of timeouts */ u32 ts_recent; struct timer_list rsk_timer; const struct request_sock_ops *rsk_ops; struct sock *sk; struct saved_syn *saved_syn; u32 secid; u32 peer_secid; }; static inline struct request_sock *inet_reqsk(const 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 struct request_sock * reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener, bool attach_listener) { struct request_sock *req; req = kmem_cache_alloc(ops->slab, GFP_ATOMIC | __GFP_NOWARN); if (!req) return NULL; req->rsk_listener = NULL; if (attach_listener) { if (unlikely(!refcount_inc_not_zero(&sk_listener->sk_refcnt))) { kmem_cache_free(ops->slab, req); return NULL; } req->rsk_listener = sk_listener; } req->rsk_ops = ops; req_to_sk(req)->sk_prot = sk_listener->sk_prot; sk_node_init(&req_to_sk(req)->sk_node); sk_tx_queue_clear(req_to_sk(req)); req->saved_syn = NULL; req->num_timeout = 0; req->num_retrans = 0; req->sk = NULL; refcount_set(&req->rsk_refcnt, 0); return req; } static inline void __reqsk_free(struct request_sock *req) { 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_free(struct request_sock *req) { WARN_ON_ONCE(refcount_read(&req->rsk_refcnt) != 0); __reqsk_free(req); } static inline void reqsk_put(struct request_sock *req) { if (refcount_dec_and_test(&req->rsk_refcnt)) reqsk_free(req); } /* * 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 tcp_fastopen_context __rcu *ctx; /* cipher context for cookie */ }; /** 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() * */ struct request_sock_queue { spinlock_t rskq_lock; u8 rskq_defer_accept; u32 synflood_warned; atomic_t qlen; atomic_t young; struct request_sock *rskq_accept_head; struct request_sock *rskq_accept_tail; struct fastopen_queue fastopenq; /* Check max_qlen != 0 to determine * if TFO is enabled. */ }; void reqsk_queue_alloc(struct request_sock_queue *queue); void reqsk_fastopen_remove(struct sock *sk, struct request_sock *req, bool reset); static inline bool reqsk_queue_empty(const struct request_sock_queue *queue) { return READ_ONCE(queue->rskq_accept_head) == NULL; } static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue, struct sock *parent) { struct request_sock *req; spin_lock_bh(&queue->rskq_lock); req = queue->rskq_accept_head; if (req) { sk_acceptq_removed(parent); WRITE_ONCE(queue->rskq_accept_head, req->dl_next); if (queue->rskq_accept_head == NULL) queue->rskq_accept_tail = NULL; } spin_unlock_bh(&queue->rskq_lock); return req; } static inline void reqsk_queue_removed(struct request_sock_queue *queue, const struct request_sock *req) { if (req->num_timeout == 0) atomic_dec(&queue->young); atomic_dec(&queue->qlen); } static inline void reqsk_queue_added(struct request_sock_queue *queue) { atomic_inc(&queue->young); atomic_inc(&queue->qlen); } static inline int reqsk_queue_len(const struct request_sock_queue *queue) { return atomic_read(&queue->qlen); } static inline int reqsk_queue_len_young(const struct request_sock_queue *queue) { return atomic_read(&queue->young); } #endif /* _REQUEST_SOCK_H */