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 | |
16 | static DEFINE_SPINLOCK(tcp_ulp_list_lock); |
17 | static LIST_HEAD(tcp_ulp_list); |
18 | |
19 | /* Simple linear search, don't expect many entries! */ |
20 | static 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 | |
32 | static 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 | |
44 | static 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 | |
66 | static 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 | */ |
81 | int 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 | } |
94 | EXPORT_SYMBOL_GPL(tcp_register_ulp); |
95 | |
96 | void 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 | } |
104 | EXPORT_SYMBOL_GPL(tcp_unregister_ulp); |
105 | |
106 | /* Build string with list of available upper layer protocl values */ |
107 | void 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 | |
122 | void 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 */ |
137 | int 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 | |
165 | int 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 | |