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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Pluggable TCP upper layer protocol support.
4 *
5 * Copyright (c) 2016-2017, Mellanox Technologies. All rights reserved.
6 * Copyright (c) 2016-2017, Dave Watson <davejwatson@fb.com>. All rights reserved.
7 *
8 */
9
10#include <linux/module.h>
11#include <linux/mm.h>
12#include <linux/types.h>
13#include <linux/list.h>
14#include <linux/gfp.h>
15#include <net/tcp.h>
16
17static DEFINE_SPINLOCK(tcp_ulp_list_lock);
18static LIST_HEAD(tcp_ulp_list);
19
20/* Simple linear search, don't expect many entries! */
21static struct tcp_ulp_ops *tcp_ulp_find(const char *name)
22{
23 struct tcp_ulp_ops *e;
24
25 list_for_each_entry_rcu(e, &tcp_ulp_list, list) {
26 if (strcmp(e->name, name) == 0)
27 return e;
28 }
29
30 return NULL;
31}
32
33static const struct tcp_ulp_ops *__tcp_ulp_find_autoload(const char *name)
34{
35 const struct tcp_ulp_ops *ulp = NULL;
36
37 rcu_read_lock();
38 ulp = tcp_ulp_find(name);
39
40#ifdef CONFIG_MODULES
41 if (!ulp && capable(CAP_NET_ADMIN)) {
42 rcu_read_unlock();
43 request_module("tcp-ulp-%s", name);
44 rcu_read_lock();
45 ulp = tcp_ulp_find(name);
46 }
47#endif
48 if (!ulp || !try_module_get(ulp->owner))
49 ulp = NULL;
50
51 rcu_read_unlock();
52 return ulp;
53}
54
55/* Attach new upper layer protocol to the list
56 * of available protocols.
57 */
58int tcp_register_ulp(struct tcp_ulp_ops *ulp)
59{
60 int ret = 0;
61
62 spin_lock(&tcp_ulp_list_lock);
63 if (tcp_ulp_find(ulp->name))
64 ret = -EEXIST;
65 else
66 list_add_tail_rcu(&ulp->list, &tcp_ulp_list);
67 spin_unlock(&tcp_ulp_list_lock);
68
69 return ret;
70}
71EXPORT_SYMBOL_GPL(tcp_register_ulp);
72
73void tcp_unregister_ulp(struct tcp_ulp_ops *ulp)
74{
75 spin_lock(&tcp_ulp_list_lock);
76 list_del_rcu(&ulp->list);
77 spin_unlock(&tcp_ulp_list_lock);
78
79 synchronize_rcu();
80}
81EXPORT_SYMBOL_GPL(tcp_unregister_ulp);
82
83/* Build string with list of available upper layer protocl values */
84void tcp_get_available_ulp(char *buf, size_t maxlen)
85{
86 struct tcp_ulp_ops *ulp_ops;
87 size_t offs = 0;
88
89 *buf = '\0';
90 rcu_read_lock();
91 list_for_each_entry_rcu(ulp_ops, &tcp_ulp_list, list) {
92 offs += snprintf(buf + offs, maxlen - offs,
93 "%s%s",
94 offs == 0 ? "" : " ", ulp_ops->name);
95 }
96 rcu_read_unlock();
97}
98
99void tcp_cleanup_ulp(struct sock *sk)
100{
101 struct inet_connection_sock *icsk = inet_csk(sk);
102
103 /* No sock_owned_by_me() check here as at the time the
104 * stack calls this function, the socket is dead and
105 * about to be destroyed.
106 */
107 if (!icsk->icsk_ulp_ops)
108 return;
109
110 if (icsk->icsk_ulp_ops->release)
111 icsk->icsk_ulp_ops->release(sk);
112 module_put(icsk->icsk_ulp_ops->owner);
113
114 icsk->icsk_ulp_ops = NULL;
115}
116
117static int __tcp_set_ulp(struct sock *sk, const struct tcp_ulp_ops *ulp_ops)
118{
119 struct inet_connection_sock *icsk = inet_csk(sk);
120 int err;
121
122 err = -EEXIST;
123 if (icsk->icsk_ulp_ops)
124 goto out_err;
125
126 err = ulp_ops->init(sk);
127 if (err)
128 goto out_err;
129
130 icsk->icsk_ulp_ops = ulp_ops;
131 return 0;
132out_err:
133 module_put(ulp_ops->owner);
134 return err;
135}
136
137int tcp_set_ulp(struct sock *sk, const char *name)
138{
139 const struct tcp_ulp_ops *ulp_ops;
140
141 sock_owned_by_me(sk);
142
143 ulp_ops = __tcp_ulp_find_autoload(name);
144 if (!ulp_ops)
145 return -ENOENT;
146
147 return __tcp_set_ulp(sk, ulp_ops);
148}