1// SPDX-License-Identifier: GPL-2.0
  2/* Multipath TCP
  3 *
  4 * Copyright (c) 2019, Intel Corporation.
  5 */
  6#define pr_fmt(fmt) "MPTCP: " fmt
  7
  8#include <linux/kernel.h>
  9#include <net/tcp.h>
 10#include <net/mptcp.h>
 11#include "protocol.h"
 12
 13/* path manager command handlers */
 14
 15int mptcp_pm_announce_addr(struct mptcp_sock *msk,
 16			   const struct mptcp_addr_info *addr)
 17{
 18	pr_debug("msk=%p, local_id=%d", msk, addr->id);
 19
 20	msk->pm.local = *addr;
 21	WRITE_ONCE(msk->pm.addr_signal, true);
 22	return 0;
 23}
 24
 25int mptcp_pm_remove_addr(struct mptcp_sock *msk, u8 local_id)
 26{
 27	return -ENOTSUPP;
 28}
 29
 30int mptcp_pm_remove_subflow(struct mptcp_sock *msk, u8 remote_id)
 31{
 32	return -ENOTSUPP;
 33}
 34
 35/* path manager event handlers */
 36
 37void mptcp_pm_new_connection(struct mptcp_sock *msk, int server_side)
 38{
 39	struct mptcp_pm_data *pm = &msk->pm;
 40
 41	pr_debug("msk=%p, token=%u side=%d", msk, msk->token, server_side);
 42
 43	WRITE_ONCE(pm->server_side, server_side);
 44}
 45
 46bool mptcp_pm_allow_new_subflow(struct mptcp_sock *msk)
 47{
 48	struct mptcp_pm_data *pm = &msk->pm;
 49	int ret;
 50
 51	pr_debug("msk=%p subflows=%d max=%d allow=%d", msk, pm->subflows,
 52		 pm->subflows_max, READ_ONCE(pm->accept_subflow));
 53
 54	/* try to avoid acquiring the lock below */
 55	if (!READ_ONCE(pm->accept_subflow))
 56		return false;
 57
 58	spin_lock_bh(&pm->lock);
 59	ret = pm->subflows < pm->subflows_max;
 60	if (ret && ++pm->subflows == pm->subflows_max)
 61		WRITE_ONCE(pm->accept_subflow, false);
 62	spin_unlock_bh(&pm->lock);
 63
 64	return ret;
 65}
 66
 67/* return true if the new status bit is currently cleared, that is, this event
 68 * can be server, eventually by an already scheduled work
 69 */
 70static bool mptcp_pm_schedule_work(struct mptcp_sock *msk,
 71				   enum mptcp_pm_status new_status)
 72{
 73	pr_debug("msk=%p status=%x new=%lx", msk, msk->pm.status,
 74		 BIT(new_status));
 75	if (msk->pm.status & BIT(new_status))
 76		return false;
 77
 78	msk->pm.status |= BIT(new_status);
 79	if (schedule_work(&msk->work))
 80		sock_hold((struct sock *)msk);
 81	return true;
 82}
 83
 84void mptcp_pm_fully_established(struct mptcp_sock *msk)
 85{
 86	struct mptcp_pm_data *pm = &msk->pm;
 87
 88	pr_debug("msk=%p", msk);
 89
 90	/* try to avoid acquiring the lock below */
 91	if (!READ_ONCE(pm->work_pending))
 92		return;
 93
 94	spin_lock_bh(&pm->lock);
 95
 96	if (READ_ONCE(pm->work_pending))
 97		mptcp_pm_schedule_work(msk, MPTCP_PM_ESTABLISHED);
 98
 99	spin_unlock_bh(&pm->lock);
100}
101
102void mptcp_pm_connection_closed(struct mptcp_sock *msk)
103{
104	pr_debug("msk=%p", msk);
105}
106
107void mptcp_pm_subflow_established(struct mptcp_sock *msk,
108				  struct mptcp_subflow_context *subflow)
109{
110	struct mptcp_pm_data *pm = &msk->pm;
111
112	pr_debug("msk=%p", msk);
113
114	if (!READ_ONCE(pm->work_pending))
115		return;
116
117	spin_lock_bh(&pm->lock);
118
119	if (READ_ONCE(pm->work_pending))
120		mptcp_pm_schedule_work(msk, MPTCP_PM_SUBFLOW_ESTABLISHED);
121
122	spin_unlock_bh(&pm->lock);
123}
124
125void mptcp_pm_subflow_closed(struct mptcp_sock *msk, u8 id)
126{
127	pr_debug("msk=%p", msk);
128}
129
130void mptcp_pm_add_addr_received(struct mptcp_sock *msk,
131				const struct mptcp_addr_info *addr)
132{
133	struct mptcp_pm_data *pm = &msk->pm;
134
135	pr_debug("msk=%p remote_id=%d accept=%d", msk, addr->id,
136		 READ_ONCE(pm->accept_addr));
137
138	/* avoid acquiring the lock if there is no room for fouther addresses */
139	if (!READ_ONCE(pm->accept_addr))
140		return;
141
142	spin_lock_bh(&pm->lock);
143
144	/* be sure there is something to signal re-checking under PM lock */
145	if (READ_ONCE(pm->accept_addr) &&
146	    mptcp_pm_schedule_work(msk, MPTCP_PM_ADD_ADDR_RECEIVED))
147		pm->remote = *addr;
148
149	spin_unlock_bh(&pm->lock);
150}
151
152/* path manager helpers */
153
154bool mptcp_pm_addr_signal(struct mptcp_sock *msk, unsigned int remaining,
155			  struct mptcp_addr_info *saddr)
156{
157	int ret = false;
158
159	spin_lock_bh(&msk->pm.lock);
160
161	/* double check after the lock is acquired */
162	if (!mptcp_pm_should_signal(msk))
163		goto out_unlock;
164
165	if (remaining < mptcp_add_addr_len(msk->pm.local.family))
166		goto out_unlock;
167
168	*saddr = msk->pm.local;
169	WRITE_ONCE(msk->pm.addr_signal, false);
170	ret = true;
171
172out_unlock:
173	spin_unlock_bh(&msk->pm.lock);
174	return ret;
175}
176
177int mptcp_pm_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
178{
179	return mptcp_pm_nl_get_local_id(msk, skc);
180}
181
182void mptcp_pm_data_init(struct mptcp_sock *msk)
183{
184	msk->pm.add_addr_signaled = 0;
185	msk->pm.add_addr_accepted = 0;
186	msk->pm.local_addr_used = 0;
187	msk->pm.subflows = 0;
188	WRITE_ONCE(msk->pm.work_pending, false);
189	WRITE_ONCE(msk->pm.addr_signal, false);
190	WRITE_ONCE(msk->pm.accept_addr, false);
191	WRITE_ONCE(msk->pm.accept_subflow, false);
192	msk->pm.status = 0;
193
194	spin_lock_init(&msk->pm.lock);
195
196	mptcp_pm_nl_data_init(msk);
197}
198
199void __init mptcp_pm_init(void)
200{
201	mptcp_pm_nl_init();
202}