132 lines
3.5 KiB
C
132 lines
3.5 KiB
C
/*
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* NET Generic infrastructure for Network protocols.
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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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#include <linux/module.h>
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#include <linux/random.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include <linux/vmalloc.h>
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#include <net/request_sock.h>
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/*
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* Maximum number of SYN_RECV sockets in queue per LISTEN socket.
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* One SYN_RECV socket costs about 80bytes on a 32bit machine.
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* It would be better to replace it with a global counter for all sockets
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* but then some measure against one socket starving all other sockets
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* would be needed.
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*
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* It was 128 by default. Experiments with real servers show, that
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* it is absolutely not enough even at 100conn/sec. 256 cures most
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* of problems. This value is adjusted to 128 for very small machines
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* (<=32Mb of memory) and to 1024 on normal or better ones (>=256Mb).
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* Note : Dont forget somaxconn that may limit backlog too.
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*/
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int sysctl_max_syn_backlog = 256;
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EXPORT_SYMBOL(sysctl_max_syn_backlog);
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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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{
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size_t lopt_size = sizeof(struct listen_sock);
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struct listen_sock *lopt;
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nr_table_entries = min_t(u32, nr_table_entries, sysctl_max_syn_backlog);
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nr_table_entries = max_t(u32, nr_table_entries, 8);
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nr_table_entries = roundup_pow_of_two(nr_table_entries + 1);
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lopt_size += nr_table_entries * sizeof(struct request_sock *);
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if (lopt_size > PAGE_SIZE)
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lopt = vzalloc(lopt_size);
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else
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lopt = kzalloc(lopt_size, GFP_KERNEL);
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if (lopt == NULL)
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return -ENOMEM;
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for (lopt->max_qlen_log = 3;
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(1 << lopt->max_qlen_log) < nr_table_entries;
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lopt->max_qlen_log++);
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get_random_bytes(&lopt->hash_rnd, sizeof(lopt->hash_rnd));
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rwlock_init(&queue->syn_wait_lock);
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queue->rskq_accept_head = NULL;
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lopt->nr_table_entries = nr_table_entries;
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write_lock_bh(&queue->syn_wait_lock);
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queue->listen_opt = lopt;
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write_unlock_bh(&queue->syn_wait_lock);
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return 0;
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}
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void __reqsk_queue_destroy(struct request_sock_queue *queue)
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{
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struct listen_sock *lopt;
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size_t lopt_size;
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/*
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* this is an error recovery path only
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* no locking needed and the lopt is not NULL
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*/
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lopt = queue->listen_opt;
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lopt_size = sizeof(struct listen_sock) +
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lopt->nr_table_entries * sizeof(struct request_sock *);
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if (lopt_size > PAGE_SIZE)
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vfree(lopt);
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else
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kfree(lopt);
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}
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static inline struct listen_sock *reqsk_queue_yank_listen_sk(
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struct request_sock_queue *queue)
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{
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struct listen_sock *lopt;
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write_lock_bh(&queue->syn_wait_lock);
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lopt = queue->listen_opt;
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queue->listen_opt = NULL;
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write_unlock_bh(&queue->syn_wait_lock);
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return lopt;
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}
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void reqsk_queue_destroy(struct request_sock_queue *queue)
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{
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/* make all the listen_opt local to us */
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struct listen_sock *lopt = reqsk_queue_yank_listen_sk(queue);
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size_t lopt_size = sizeof(struct listen_sock) +
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lopt->nr_table_entries * sizeof(struct request_sock *);
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if (lopt->qlen != 0) {
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unsigned int i;
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for (i = 0; i < lopt->nr_table_entries; i++) {
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struct request_sock *req;
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while ((req = lopt->syn_table[i]) != NULL) {
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lopt->syn_table[i] = req->dl_next;
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lopt->qlen--;
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reqsk_free(req);
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}
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}
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}
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WARN_ON(lopt->qlen != 0);
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if (lopt_size > PAGE_SIZE)
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vfree(lopt);
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else
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kfree(lopt);
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}
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