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// SPDX-License-Identifier: GPL-2.0-only
/*
* Pluggable TCP upper layer protocol support.
*
* Copyright (c) 2016-2017, Mellanox Technologies. All rights reserved.
* Copyright (c) 2016-2017, Dave Watson <davejwatson@fb.com>. All rights reserved.
*
*/
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/gfp.h>
#include <net/tcp.h>
static DEFINE_SPINLOCK(tcp_ulp_list_lock);
static LIST_HEAD(tcp_ulp_list);
/* Simple linear search, don't expect many entries! */
static struct tcp_ulp_ops *tcp_ulp_find(const char *name)
{
struct tcp_ulp_ops *e;
list_for_each_entry_rcu(e, &tcp_ulp_list, list) {
if (strcmp(e->name, name) == 0)
return e;
}
return NULL;
}
static const struct tcp_ulp_ops *__tcp_ulp_find_autoload(const char *name)
{
const struct tcp_ulp_ops *ulp = NULL;
rcu_read_lock();
ulp = tcp_ulp_find(name);
#ifdef CONFIG_MODULES
if (!ulp && capable(CAP_NET_ADMIN)) {
rcu_read_unlock();
request_module("tcp-ulp-%s", name);
rcu_read_lock();
ulp = tcp_ulp_find(name);
}
#endif
if (!ulp || !try_module_get(ulp->owner))
ulp = NULL;
rcu_read_unlock();
return ulp;
}
/* Attach new upper layer protocol to the list
* of available protocols.
*/
int tcp_register_ulp(struct tcp_ulp_ops *ulp)
{
int ret = 0;
spin_lock(&tcp_ulp_list_lock);
if (tcp_ulp_find(ulp->name))
ret = -EEXIST;
else
list_add_tail_rcu(&ulp->list, &tcp_ulp_list);
spin_unlock(&tcp_ulp_list_lock);
return ret;
}
EXPORT_SYMBOL_GPL(tcp_register_ulp);
void tcp_unregister_ulp(struct tcp_ulp_ops *ulp)
{
spin_lock(&tcp_ulp_list_lock);
list_del_rcu(&ulp->list);
spin_unlock(&tcp_ulp_list_lock);
synchronize_rcu();
}
EXPORT_SYMBOL_GPL(tcp_unregister_ulp);
/* Build string with list of available upper layer protocl values */
void tcp_get_available_ulp(char *buf, size_t maxlen)
{
struct tcp_ulp_ops *ulp_ops;
size_t offs = 0;
*buf = '\0';
rcu_read_lock();
list_for_each_entry_rcu(ulp_ops, &tcp_ulp_list, list) {
offs += snprintf(buf + offs, maxlen - offs,
"%s%s",
offs == 0 ? "" : " ", ulp_ops->name);
if (WARN_ON_ONCE(offs >= maxlen))
break;
}
rcu_read_unlock();
}
void tcp_update_ulp(struct sock *sk, struct proto *proto,
void (*write_space)(struct sock *sk))
{
struct inet_connection_sock *icsk = inet_csk(sk);
if (!icsk->icsk_ulp_ops) {
sk->sk_write_space = write_space;
sk->sk_prot = proto;
return;
}
if (icsk->icsk_ulp_ops->update)
icsk->icsk_ulp_ops->update(sk, proto, write_space);
}
void tcp_cleanup_ulp(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
/* No sock_owned_by_me() check here as at the time the
* stack calls this function, the socket is dead and
* about to be destroyed.
*/
if (!icsk->icsk_ulp_ops)
return;
if (icsk->icsk_ulp_ops->release)
icsk->icsk_ulp_ops->release(sk);
module_put(icsk->icsk_ulp_ops->owner);
icsk->icsk_ulp_ops = NULL;
}
static int __tcp_set_ulp(struct sock *sk, const struct tcp_ulp_ops *ulp_ops)
{
struct inet_connection_sock *icsk = inet_csk(sk);
int err;
err = -EEXIST;
if (icsk->icsk_ulp_ops)
goto out_err;
err = ulp_ops->init(sk);
if (err)
goto out_err;
icsk->icsk_ulp_ops = ulp_ops;
return 0;
out_err:
module_put(ulp_ops->owner);
return err;
}
int tcp_set_ulp(struct sock *sk, const char *name)
{
const struct tcp_ulp_ops *ulp_ops;
sock_owned_by_me(sk);
ulp_ops = __tcp_ulp_find_autoload(name);
if (!ulp_ops)
return -ENOENT;
return __tcp_set_ulp(sk, ulp_ops);
}
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