1/*
2 * Pluggable TCP upper layer protocol support.
3 *
4 * Copyright (c) 2016-2017, Mellanox Technologies. All rights reserved.
5 * Copyright (c) 2016-2017, Dave Watson <davejwatson@fb.com>. All rights reserved.
6 *
7 */
8
9#include<linux/module.h>
10#include <linux/mm.h>
11#include <linux/types.h>
12#include <linux/list.h>
13#include <linux/gfp.h>
14#include <net/tcp.h>
15
16static DEFINE_SPINLOCK(tcp_ulp_list_lock);
17static LIST_HEAD(tcp_ulp_list);
18
19/* Simple linear search, don't expect many entries! */
20static struct tcp_ulp_ops *tcp_ulp_find(const char *name)
21{
22 struct tcp_ulp_ops *e;
23
24 list_for_each_entry_rcu(e, &tcp_ulp_list, list) {
25 if (strcmp(e->name, name) == 0)
26 return e;
27 }
28
29 return NULL;
30}
31
32static struct tcp_ulp_ops *tcp_ulp_find_id(const int ulp)
33{
34 struct tcp_ulp_ops *e;
35
36 list_for_each_entry_rcu(e, &tcp_ulp_list, list) {
37 if (e->uid == ulp)
38 return e;
39 }
40
41 return NULL;
42}
43
44static const struct tcp_ulp_ops *__tcp_ulp_find_autoload(const char *name)
45{
46 const struct tcp_ulp_ops *ulp = NULL;
47
48 rcu_read_lock();
49 ulp = tcp_ulp_find(name);
50
51#ifdef CONFIG_MODULES
52 if (!ulp && capable(CAP_NET_ADMIN)) {
53 rcu_read_unlock();
54 request_module("tcp-ulp-%s", name);
55 rcu_read_lock();
56 ulp = tcp_ulp_find(name);
57 }
58#endif
59 if (!ulp || !try_module_get(ulp->owner))
60 ulp = NULL;
61
62 rcu_read_unlock();
63 return ulp;
64}
65
66static const struct tcp_ulp_ops *__tcp_ulp_lookup(const int uid)
67{
68 const struct tcp_ulp_ops *ulp;
69
70 rcu_read_lock();
71 ulp = tcp_ulp_find_id(uid);
72 if (!ulp || !try_module_get(ulp->owner))
73 ulp = NULL;
74 rcu_read_unlock();
75 return ulp;
76}
77
78/* Attach new upper layer protocol to the list
79 * of available protocols.
80 */
81int tcp_register_ulp(struct tcp_ulp_ops *ulp)
82{
83 int ret = 0;
84
85 spin_lock(&tcp_ulp_list_lock);
86 if (tcp_ulp_find(ulp->name))
87 ret = -EEXIST;
88 else
89 list_add_tail_rcu(&ulp->list, &tcp_ulp_list);
90 spin_unlock(&tcp_ulp_list_lock);
91
92 return ret;
93}
94EXPORT_SYMBOL_GPL(tcp_register_ulp);
95
96void tcp_unregister_ulp(struct tcp_ulp_ops *ulp)
97{
98 spin_lock(&tcp_ulp_list_lock);
99 list_del_rcu(&ulp->list);
100 spin_unlock(&tcp_ulp_list_lock);
101
102 synchronize_rcu();
103}
104EXPORT_SYMBOL_GPL(tcp_unregister_ulp);
105
106/* Build string with list of available upper layer protocl values */
107void tcp_get_available_ulp(char *buf, size_t maxlen)
108{
109 struct tcp_ulp_ops *ulp_ops;
110 size_t offs = 0;
111
112 *buf = '\0';
113 rcu_read_lock();
114 list_for_each_entry_rcu(ulp_ops, &tcp_ulp_list, list) {
115 offs += snprintf(buf + offs, maxlen - offs,
116 "%s%s",
117 offs == 0 ? "" : " ", ulp_ops->name);
118 }
119 rcu_read_unlock();
120}
121
122void tcp_cleanup_ulp(struct sock *sk)
123{
124 struct inet_connection_sock *icsk = inet_csk(sk);
125
126 if (!icsk->icsk_ulp_ops)
127 return;
128
129 if (icsk->icsk_ulp_ops->release)
130 icsk->icsk_ulp_ops->release(sk);
131 module_put(icsk->icsk_ulp_ops->owner);
132
133 icsk->icsk_ulp_ops = NULL;
134}
135
136/* Change upper layer protocol for socket */
137int tcp_set_ulp(struct sock *sk, const char *name)
138{
139 struct inet_connection_sock *icsk = inet_csk(sk);
140 const struct tcp_ulp_ops *ulp_ops;
141 int err = 0;
142
143 if (icsk->icsk_ulp_ops)
144 return -EEXIST;
145
146 ulp_ops = __tcp_ulp_find_autoload(name);
147 if (!ulp_ops)
148 return -ENOENT;
149
150 if (!ulp_ops->user_visible) {
151 module_put(ulp_ops->owner);
152 return -ENOENT;
153 }
154
155 err = ulp_ops->init(sk);
156 if (err) {
157 module_put(ulp_ops->owner);
158 return err;
159 }
160
161 icsk->icsk_ulp_ops = ulp_ops;
162 return 0;
163}
164
165int tcp_set_ulp_id(struct sock *sk, int ulp)
166{
167 struct inet_connection_sock *icsk = inet_csk(sk);
168 const struct tcp_ulp_ops *ulp_ops;
169 int err;
170
171 if (icsk->icsk_ulp_ops)
172 return -EEXIST;
173
174 ulp_ops = __tcp_ulp_lookup(ulp);
175 if (!ulp_ops)
176 return -ENOENT;
177
178 err = ulp_ops->init(sk);
179 if (err) {
180 module_put(ulp_ops->owner);
181 return err;
182 }
183
184 icsk->icsk_ulp_ops = ulp_ops;
185 return 0;
186}
187