| /* |
| * 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)(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); |
| 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 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; |
| |
| u32 max_qlen_log ____cacheline_aligned_in_smp; |
| u32 synflood_warned; |
| 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; /* Check max_qlen != 0 to determine |
| * if TFO is enabled. |
| */ |
| |
| /* 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 */ |