xref: /openbmc/linux/net/mptcp/token.c (revision 022dacdd)
1 // SPDX-License-Identifier: GPL-2.0
2 /* Multipath TCP token management
3  * Copyright (c) 2017 - 2019, Intel Corporation.
4  *
5  * Note: This code is based on mptcp_ctrl.c from multipath-tcp.org,
6  *       authored by:
7  *
8  *       Sébastien Barré <sebastien.barre@uclouvain.be>
9  *       Christoph Paasch <christoph.paasch@uclouvain.be>
10  *       Jaakko Korkeaniemi <jaakko.korkeaniemi@aalto.fi>
11  *       Gregory Detal <gregory.detal@uclouvain.be>
12  *       Fabien Duchêne <fabien.duchene@uclouvain.be>
13  *       Andreas Seelinger <Andreas.Seelinger@rwth-aachen.de>
14  *       Lavkesh Lahngir <lavkesh51@gmail.com>
15  *       Andreas Ripke <ripke@neclab.eu>
16  *       Vlad Dogaru <vlad.dogaru@intel.com>
17  *       Octavian Purdila <octavian.purdila@intel.com>
18  *       John Ronan <jronan@tssg.org>
19  *       Catalin Nicutar <catalin.nicutar@gmail.com>
20  *       Brandon Heller <brandonh@stanford.edu>
21  */
22 
23 #define pr_fmt(fmt) "MPTCP: " fmt
24 
25 #include <linux/kernel.h>
26 #include <linux/module.h>
27 #include <linux/radix-tree.h>
28 #include <linux/ip.h>
29 #include <linux/tcp.h>
30 #include <net/sock.h>
31 #include <net/inet_common.h>
32 #include <net/protocol.h>
33 #include <net/mptcp.h>
34 #include "protocol.h"
35 
36 static RADIX_TREE(token_tree, GFP_ATOMIC);
37 static RADIX_TREE(token_req_tree, GFP_ATOMIC);
38 static DEFINE_SPINLOCK(token_tree_lock);
39 static int token_used __read_mostly;
40 
41 /**
42  * mptcp_token_new_request - create new key/idsn/token for subflow_request
43  * @req: the request socket
44  *
45  * This function is called when a new mptcp connection is coming in.
46  *
47  * It creates a unique token to identify the new mptcp connection,
48  * a secret local key and the initial data sequence number (idsn).
49  *
50  * Returns 0 on success.
51  */
52 int mptcp_token_new_request(struct request_sock *req)
53 {
54 	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
55 	int err;
56 
57 	while (1) {
58 		u32 token;
59 
60 		mptcp_crypto_key_gen_sha(&subflow_req->local_key,
61 					 &subflow_req->token,
62 					 &subflow_req->idsn);
63 		pr_debug("req=%p local_key=%llu, token=%u, idsn=%llu\n",
64 			 req, subflow_req->local_key, subflow_req->token,
65 			 subflow_req->idsn);
66 
67 		token = subflow_req->token;
68 		spin_lock_bh(&token_tree_lock);
69 		if (!radix_tree_lookup(&token_req_tree, token) &&
70 		    !radix_tree_lookup(&token_tree, token))
71 			break;
72 		spin_unlock_bh(&token_tree_lock);
73 	}
74 
75 	err = radix_tree_insert(&token_req_tree,
76 				subflow_req->token, &token_used);
77 	spin_unlock_bh(&token_tree_lock);
78 	return err;
79 }
80 
81 /**
82  * mptcp_token_new_connect - create new key/idsn/token for subflow
83  * @sk: the socket that will initiate a connection
84  *
85  * This function is called when a new outgoing mptcp connection is
86  * initiated.
87  *
88  * It creates a unique token to identify the new mptcp connection,
89  * a secret local key and the initial data sequence number (idsn).
90  *
91  * On success, the mptcp connection can be found again using
92  * the computed token at a later time, this is needed to process
93  * join requests.
94  *
95  * returns 0 on success.
96  */
97 int mptcp_token_new_connect(struct sock *sk)
98 {
99 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
100 	struct sock *mptcp_sock = subflow->conn;
101 	int err;
102 
103 	while (1) {
104 		u32 token;
105 
106 		mptcp_crypto_key_gen_sha(&subflow->local_key, &subflow->token,
107 					 &subflow->idsn);
108 
109 		pr_debug("ssk=%p, local_key=%llu, token=%u, idsn=%llu\n",
110 			 sk, subflow->local_key, subflow->token, subflow->idsn);
111 
112 		token = subflow->token;
113 		spin_lock_bh(&token_tree_lock);
114 		if (!radix_tree_lookup(&token_req_tree, token) &&
115 		    !radix_tree_lookup(&token_tree, token))
116 			break;
117 		spin_unlock_bh(&token_tree_lock);
118 	}
119 	err = radix_tree_insert(&token_tree, subflow->token, mptcp_sock);
120 	spin_unlock_bh(&token_tree_lock);
121 
122 	return err;
123 }
124 
125 /**
126  * mptcp_token_new_accept - insert token for later processing
127  * @token: the token to insert to the tree
128  * @conn: the just cloned socket linked to the new connection
129  *
130  * Called when a SYN packet creates a new logical connection, i.e.
131  * is not a join request.
132  */
133 int mptcp_token_new_accept(u32 token, struct sock *conn)
134 {
135 	int err;
136 
137 	spin_lock_bh(&token_tree_lock);
138 	err = radix_tree_insert(&token_tree, token, conn);
139 	spin_unlock_bh(&token_tree_lock);
140 
141 	return err;
142 }
143 
144 /**
145  * mptcp_token_get_sock - retrieve mptcp connection sock using its token
146  * @token: token of the mptcp connection to retrieve
147  *
148  * This function returns the mptcp connection structure with the given token.
149  * A reference count on the mptcp socket returned is taken.
150  *
151  * returns NULL if no connection with the given token value exists.
152  */
153 struct mptcp_sock *mptcp_token_get_sock(u32 token)
154 {
155 	struct sock *conn;
156 
157 	spin_lock_bh(&token_tree_lock);
158 	conn = radix_tree_lookup(&token_tree, token);
159 	if (conn) {
160 		/* token still reserved? */
161 		if (conn == (struct sock *)&token_used)
162 			conn = NULL;
163 		else
164 			sock_hold(conn);
165 	}
166 	spin_unlock_bh(&token_tree_lock);
167 
168 	return mptcp_sk(conn);
169 }
170 
171 /**
172  * mptcp_token_destroy_request - remove mptcp connection/token
173  * @token: token of mptcp connection to remove
174  *
175  * Remove not-yet-fully-established incoming connection identified
176  * by @token.
177  */
178 void mptcp_token_destroy_request(u32 token)
179 {
180 	spin_lock_bh(&token_tree_lock);
181 	radix_tree_delete(&token_req_tree, token);
182 	spin_unlock_bh(&token_tree_lock);
183 }
184 
185 /**
186  * mptcp_token_destroy - remove mptcp connection/token
187  * @token: token of mptcp connection to remove
188  *
189  * Remove the connection identified by @token.
190  */
191 void mptcp_token_destroy(u32 token)
192 {
193 	spin_lock_bh(&token_tree_lock);
194 	radix_tree_delete(&token_tree, token);
195 	spin_unlock_bh(&token_tree_lock);
196 }
197