linux/net/ipv4/tcp_ulp.c
John Fastabend b11a632c44 net: add a UID to use for ULP socket assignment
Create a UID field and enum that can be used to assign ULPs to
sockets. This saves a set of string comparisons if the ULP id
is known.

For sockmap, which is added in the next patches, a ULP is used to
hook into TCP sockets close state. In this case the ULP being added
is done at map insert time and the ULP is known and done on the kernel
side. In this case the named lookup is not needed. Because we don't
want to expose psock internals to user space socket options a user
visible flag is also added. For TLS this is set for BPF it will be
cleared.

Alos remove pr_notice, user gets an error code back and should check
that rather than rely on logs.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2018-02-06 11:39:31 +01:00

185 lines
3.6 KiB
C

/*
* 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 struct tcp_ulp_ops *tcp_ulp_find_id(const int ulp)
{
struct tcp_ulp_ops *e;
list_for_each_entry_rcu(e, &tcp_ulp_list, list) {
if (e->uid == ulp)
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("%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;
}
static const struct tcp_ulp_ops *__tcp_ulp_lookup(const int uid)
{
const struct tcp_ulp_ops *ulp;
rcu_read_lock();
ulp = tcp_ulp_find_id(uid);
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);
}
rcu_read_unlock();
}
void tcp_cleanup_ulp(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
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);
}
/* Change upper layer protocol for socket */
int tcp_set_ulp(struct sock *sk, const char *name)
{
struct inet_connection_sock *icsk = inet_csk(sk);
const struct tcp_ulp_ops *ulp_ops;
int err = 0;
if (icsk->icsk_ulp_ops)
return -EEXIST;
ulp_ops = __tcp_ulp_find_autoload(name);
if (!ulp_ops)
return -ENOENT;
if (!ulp_ops->user_visible) {
module_put(ulp_ops->owner);
return -ENOENT;
}
err = ulp_ops->init(sk);
if (err) {
module_put(ulp_ops->owner);
return err;
}
icsk->icsk_ulp_ops = ulp_ops;
return 0;
}
int tcp_set_ulp_id(struct sock *sk, int ulp)
{
struct inet_connection_sock *icsk = inet_csk(sk);
const struct tcp_ulp_ops *ulp_ops;
int err;
if (icsk->icsk_ulp_ops)
return -EEXIST;
ulp_ops = __tcp_ulp_lookup(ulp);
if (!ulp_ops)
return -ENOENT;
err = ulp_ops->init(sk);
if (err) {
module_put(ulp_ops->owner);
return err;
}
icsk->icsk_ulp_ops = ulp_ops;
return 0;
}