281 lines
8.0 KiB
C
281 lines
8.0 KiB
C
/*
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* NET Generic infrastructure for Network protocols.
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*
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* Definitions for request_sock
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*
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* Authors: Arnaldo Carvalho de Melo <acme@conectiva.com.br>
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*
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* From code originally in include/net/tcp.h
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _REQUEST_SOCK_H
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#define _REQUEST_SOCK_H
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/types.h>
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#include <linux/bug.h>
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#include <net/sock.h>
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struct request_sock;
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struct sk_buff;
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struct dst_entry;
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struct proto;
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struct request_sock_ops {
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int family;
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int obj_size;
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struct kmem_cache *slab;
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char *slab_name;
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int (*rtx_syn_ack)(struct sock *sk,
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struct request_sock *req);
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void (*send_ack)(struct sock *sk, struct sk_buff *skb,
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struct request_sock *req);
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void (*send_reset)(struct sock *sk,
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struct sk_buff *skb);
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void (*destructor)(struct request_sock *req);
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void (*syn_ack_timeout)(struct sock *sk,
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struct request_sock *req);
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};
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int inet_rtx_syn_ack(struct sock *parent, struct request_sock *req);
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/* struct request_sock - mini sock to represent a connection request
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*/
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struct request_sock {
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struct sock_common __req_common;
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struct request_sock *dl_next;
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u16 mss;
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u8 num_retrans; /* number of retransmits */
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u8 cookie_ts:1; /* syncookie: encode tcpopts in timestamp */
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u8 num_timeout:7; /* number of timeouts */
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/* The following two fields can be easily recomputed I think -AK */
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u32 window_clamp; /* window clamp at creation time */
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u32 rcv_wnd; /* rcv_wnd offered first time */
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u32 ts_recent;
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unsigned long expires;
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const struct request_sock_ops *rsk_ops;
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struct sock *sk;
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u32 secid;
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u32 peer_secid;
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};
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static inline struct request_sock *reqsk_alloc(const struct request_sock_ops *ops)
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{
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struct request_sock *req = kmem_cache_alloc(ops->slab, GFP_ATOMIC);
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if (req != NULL)
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req->rsk_ops = ops;
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return req;
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}
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static inline void __reqsk_free(struct request_sock *req)
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{
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kmem_cache_free(req->rsk_ops->slab, req);
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}
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static inline void reqsk_free(struct request_sock *req)
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{
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req->rsk_ops->destructor(req);
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__reqsk_free(req);
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}
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extern int sysctl_max_syn_backlog;
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/** struct listen_sock - listen state
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*
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* @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs
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*/
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struct listen_sock {
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u8 max_qlen_log;
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u8 synflood_warned;
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/* 2 bytes hole, try to use */
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int qlen;
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int qlen_young;
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int clock_hand;
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u32 hash_rnd;
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u32 nr_table_entries;
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struct request_sock *syn_table[0];
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};
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/*
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* For a TCP Fast Open listener -
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* lock - protects the access to all the reqsk, which is co-owned by
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* the listener and the child socket.
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* qlen - pending TFO requests (still in TCP_SYN_RECV).
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* max_qlen - max TFO reqs allowed before TFO is disabled.
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*
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* XXX (TFO) - ideally these fields can be made as part of "listen_sock"
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* structure above. But there is some implementation difficulty due to
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* listen_sock being part of request_sock_queue hence will be freed when
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* a listener is stopped. But TFO related fields may continue to be
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* accessed even after a listener is closed, until its sk_refcnt drops
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* to 0 implying no more outstanding TFO reqs. One solution is to keep
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* listen_opt around until sk_refcnt drops to 0. But there is some other
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* complexity that needs to be resolved. E.g., a listener can be disabled
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* temporarily through shutdown()->tcp_disconnect(), and re-enabled later.
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*/
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struct fastopen_queue {
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struct request_sock *rskq_rst_head; /* Keep track of past TFO */
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struct request_sock *rskq_rst_tail; /* requests that caused RST.
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* This is part of the defense
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* against spoofing attack.
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*/
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spinlock_t lock;
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int qlen; /* # of pending (TCP_SYN_RECV) reqs */
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int max_qlen; /* != 0 iff TFO is currently enabled */
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};
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/** struct request_sock_queue - queue of request_socks
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*
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* @rskq_accept_head - FIFO head of established children
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* @rskq_accept_tail - FIFO tail of established children
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* @rskq_defer_accept - User waits for some data after accept()
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* @syn_wait_lock - serializer
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*
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* %syn_wait_lock is necessary only to avoid proc interface having to grab the main
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* lock sock while browsing the listening hash (otherwise it's deadlock prone).
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*
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* This lock is acquired in read mode only from listening_get_next() seq_file
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* op and it's acquired in write mode _only_ from code that is actively
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* changing rskq_accept_head. All readers that are holding the master sock lock
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* don't need to grab this lock in read mode too as rskq_accept_head. writes
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* are always protected from the main sock lock.
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*/
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struct request_sock_queue {
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struct request_sock *rskq_accept_head;
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struct request_sock *rskq_accept_tail;
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rwlock_t syn_wait_lock;
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u8 rskq_defer_accept;
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/* 3 bytes hole, try to pack */
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struct listen_sock *listen_opt;
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struct fastopen_queue *fastopenq; /* This is non-NULL iff TFO has been
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* enabled on this listener. Check
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* max_qlen != 0 in fastopen_queue
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* to determine if TFO is enabled
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* right at this moment.
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*/
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};
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int reqsk_queue_alloc(struct request_sock_queue *queue,
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unsigned int nr_table_entries);
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void __reqsk_queue_destroy(struct request_sock_queue *queue);
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void reqsk_queue_destroy(struct request_sock_queue *queue);
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void reqsk_fastopen_remove(struct sock *sk, struct request_sock *req,
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bool reset);
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static inline struct request_sock *
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reqsk_queue_yank_acceptq(struct request_sock_queue *queue)
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{
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struct request_sock *req = queue->rskq_accept_head;
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queue->rskq_accept_head = NULL;
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return req;
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}
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static inline int reqsk_queue_empty(struct request_sock_queue *queue)
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{
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return queue->rskq_accept_head == NULL;
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}
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static inline void reqsk_queue_unlink(struct request_sock_queue *queue,
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struct request_sock *req,
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struct request_sock **prev_req)
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{
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write_lock(&queue->syn_wait_lock);
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*prev_req = req->dl_next;
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write_unlock(&queue->syn_wait_lock);
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}
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static inline void reqsk_queue_add(struct request_sock_queue *queue,
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struct request_sock *req,
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struct sock *parent,
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struct sock *child)
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{
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req->sk = child;
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sk_acceptq_added(parent);
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if (queue->rskq_accept_head == NULL)
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queue->rskq_accept_head = req;
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else
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queue->rskq_accept_tail->dl_next = req;
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queue->rskq_accept_tail = req;
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req->dl_next = NULL;
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}
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static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
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{
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struct request_sock *req = queue->rskq_accept_head;
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WARN_ON(req == NULL);
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queue->rskq_accept_head = req->dl_next;
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if (queue->rskq_accept_head == NULL)
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queue->rskq_accept_tail = NULL;
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return req;
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}
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static inline int reqsk_queue_removed(struct request_sock_queue *queue,
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struct request_sock *req)
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{
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struct listen_sock *lopt = queue->listen_opt;
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if (req->num_timeout == 0)
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--lopt->qlen_young;
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return --lopt->qlen;
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}
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static inline int reqsk_queue_added(struct request_sock_queue *queue)
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{
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struct listen_sock *lopt = queue->listen_opt;
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const int prev_qlen = lopt->qlen;
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lopt->qlen_young++;
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lopt->qlen++;
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return prev_qlen;
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}
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static inline int reqsk_queue_len(const struct request_sock_queue *queue)
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{
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return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0;
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}
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static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
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{
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return queue->listen_opt->qlen_young;
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}
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static inline int reqsk_queue_is_full(const struct request_sock_queue *queue)
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{
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return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log;
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}
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static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
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u32 hash, struct request_sock *req,
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unsigned long timeout)
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{
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struct listen_sock *lopt = queue->listen_opt;
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req->expires = jiffies + timeout;
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req->num_retrans = 0;
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req->num_timeout = 0;
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req->sk = NULL;
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req->dl_next = lopt->syn_table[hash];
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write_lock(&queue->syn_wait_lock);
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lopt->syn_table[hash] = req;
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write_unlock(&queue->syn_wait_lock);
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}
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#endif /* _REQUEST_SOCK_H */
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