// SPDX-License-Identifier: GPL-2.0/* Multipath TCP * * Copyright (c) 2019, Tessares SA. */ #ifdef CONFIG_SYSCTL#include <linux/sysctl.h>#endif #include <net/net_namespace.h>#include <net/netns/generic.h> #include "protocol.h"#include "mib.h" #define MPTCP_SYSCTL_PATH "net/mptcp" static int mptcp_pernet_id; #ifdef CONFIG_SYSCTLstatic int mptcp_pm_type_max = __MPTCP_PM_TYPE_MAX;#endif struct mptcp_pernet {#ifdef CONFIG_SYSCTL	struct ctl_table_header *ctl_table_hdr;#endif 	unsigned int add_addr_timeout;	unsigned int blackhole_timeout;	unsigned int close_timeout;	unsigned int stale_loss_cnt;	atomic_t active_disable_times;	unsigned long active_disable_stamp;	u8 mptcp_enabled;	u8 checksum_enabled;	u8 allow_join_initial_addr_port;	u8 pm_type;	char scheduler[MPTCP_SCHED_NAME_MAX];}; static struct mptcp_pernet *mptcp_get_pernet(const struct net *net){	return net_generic(net, mptcp_pernet_id);} int mptcp_is_enabled(const struct net *net){	return mptcp_get_pernet(net)->mptcp_enabled;} unsigned int mptcp_get_add_addr_timeout(const struct net *net){	return mptcp_get_pernet(net)->add_addr_timeout;} int mptcp_is_checksum_enabled(const struct net *net){	return mptcp_get_pernet(net)->checksum_enabled;} int mptcp_allow_join_id0(const struct net *net){	return mptcp_get_pernet(net)->allow_join_initial_addr_port;} unsigned int mptcp_stale_loss_cnt(const struct net *net){	return mptcp_get_pernet(net)->stale_loss_cnt;} unsigned int mptcp_close_timeout(const struct sock *sk){	if (sock_flag(sk, SOCK_DEAD))		return TCP_TIMEWAIT_LEN;	return mptcp_get_pernet(sock_net(sk))->close_timeout;} int mptcp_get_pm_type(const struct net *net){	return mptcp_get_pernet(net)->pm_type;} const char *mptcp_get_scheduler(const struct net *net){	return mptcp_get_pernet(net)->scheduler;} static void mptcp_pernet_set_defaults(struct mptcp_pernet *pernet){	pernet->mptcp_enabled = 1;	pernet->add_addr_timeout = TCP_RTO_MAX;	pernet->blackhole_timeout = 3600;	atomic_set(&pernet->active_disable_times, 0);	pernet->close_timeout = TCP_TIMEWAIT_LEN;	pernet->checksum_enabled = 0;	pernet->allow_join_initial_addr_port = 1;	pernet->stale_loss_cnt = 4;	pernet->pm_type = MPTCP_PM_TYPE_KERNEL;	strscpy(pernet->scheduler, "default", sizeof(pernet->scheduler));} #ifdef CONFIG_SYSCTLstatic int mptcp_set_scheduler(char *scheduler, const char *name){	struct mptcp_sched_ops *sched;	int ret = 0; 	rcu_read_lock();	sched = mptcp_sched_find(name);	if (sched)		strscpy(scheduler, name, MPTCP_SCHED_NAME_MAX);	else		ret = -ENOENT;	rcu_read_unlock(); 	return ret;} static int proc_scheduler(const struct ctl_table *ctl, int write,			  void *buffer, size_t *lenp, loff_t *ppos){	char (*scheduler)[MPTCP_SCHED_NAME_MAX] = ctl->data;	char val[MPTCP_SCHED_NAME_MAX];	struct ctl_table tbl = {		.data = val,		.maxlen = MPTCP_SCHED_NAME_MAX,	};	int ret; 	strscpy(val, *scheduler, MPTCP_SCHED_NAME_MAX); 	ret = proc_dostring(&tbl, write, buffer, lenp, ppos);	if (write && ret == 0)		ret = mptcp_set_scheduler(*scheduler, val); 	return ret;} static int proc_available_schedulers(const struct ctl_table *ctl,				     int write, void *buffer,				     size_t *lenp, loff_t *ppos){	struct ctl_table tbl = { .maxlen = MPTCP_SCHED_BUF_MAX, };	int ret; 	tbl.data = kmalloc(tbl.maxlen, GFP_USER);	if (!tbl.data)		return -ENOMEM; 	mptcp_get_available_schedulers(tbl.data, MPTCP_SCHED_BUF_MAX);	ret = proc_dostring(&tbl, write, buffer, lenp, ppos);	kfree(tbl.data); 	return ret;} static int proc_blackhole_detect_timeout(const struct ctl_table *table,					 int write, void *buffer, size_t *lenp,					 loff_t *ppos){	struct mptcp_pernet *pernet = container_of(table->data,						   struct mptcp_pernet,						   blackhole_timeout);	int ret; 	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);	if (write && ret == 0)		atomic_set(&pernet->active_disable_times, 0); 	return ret;} static struct ctl_table mptcp_sysctl_table[] = {	{		.procname = "enabled",		.maxlen = sizeof(u8),		.mode = 0644,		/* users with CAP_NET_ADMIN or root (not and) can change this		 * value, same as other sysctl or the 'net' tree.		 */		.proc_handler = proc_dou8vec_minmax,		.extra1       = SYSCTL_ZERO,		.extra2       = SYSCTL_ONE	},	{		.procname = "add_addr_timeout",		.maxlen = sizeof(unsigned int),		.mode = 0644,		.proc_handler = proc_dointvec_jiffies,	},	{		.procname = "checksum_enabled",		.maxlen = sizeof(u8),		.mode = 0644,		.proc_handler = proc_dou8vec_minmax,		.extra1       = SYSCTL_ZERO,		.extra2       = SYSCTL_ONE	},	{		.procname = "allow_join_initial_addr_port",		.maxlen = sizeof(u8),		.mode = 0644,		.proc_handler = proc_dou8vec_minmax,		.extra1       = SYSCTL_ZERO,		.extra2       = SYSCTL_ONE	},	{		.procname = "stale_loss_cnt",		.maxlen = sizeof(unsigned int),		.mode = 0644,		.proc_handler = proc_douintvec_minmax,	},	{		.procname = "pm_type",		.maxlen = sizeof(u8),		.mode = 0644,		.proc_handler = proc_dou8vec_minmax,		.extra1       = SYSCTL_ZERO,		.extra2       = &mptcp_pm_type_max	},	{		.procname = "scheduler",		.maxlen	= MPTCP_SCHED_NAME_MAX,		.mode = 0644,		.proc_handler = proc_scheduler,	},	{		.procname = "available_schedulers",		.maxlen	= MPTCP_SCHED_BUF_MAX,		.mode = 0444,		.proc_handler = proc_available_schedulers,	},	{		.procname = "close_timeout",		.maxlen = sizeof(unsigned int),		.mode = 0644,		.proc_handler = proc_dointvec_jiffies,	},	{		.procname = "blackhole_timeout",		.maxlen = sizeof(unsigned int),		.mode = 0644,		.proc_handler = proc_blackhole_detect_timeout,		.extra1 = SYSCTL_ZERO,	},}; static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet){	struct ctl_table_header *hdr;	struct ctl_table *table; 	table = mptcp_sysctl_table;	if (!net_eq(net, &init_net)) {		table = kmemdup(table, sizeof(mptcp_sysctl_table), GFP_KERNEL);		if (!table)			goto err_alloc;	} 	table[0].data = &pernet->mptcp_enabled;	table[1].data = &pernet->add_addr_timeout;	table[2].data = &pernet->checksum_enabled;	table[3].data = &pernet->allow_join_initial_addr_port;	table[4].data = &pernet->stale_loss_cnt;	table[5].data = &pernet->pm_type;	table[6].data = &pernet->scheduler;	/* table[7] is for available_schedulers which is read-only info */	table[8].data = &pernet->close_timeout;	table[9].data = &pernet->blackhole_timeout; 	hdr = register_net_sysctl_sz(net, MPTCP_SYSCTL_PATH, table,				     ARRAY_SIZE(mptcp_sysctl_table));	if (!hdr)		goto err_reg; 	pernet->ctl_table_hdr = hdr; 	return 0; err_reg:	if (!net_eq(net, &init_net))		kfree(table);err_alloc:	return -ENOMEM;} static void mptcp_pernet_del_table(struct mptcp_pernet *pernet){	const struct ctl_table *table = pernet->ctl_table_hdr->ctl_table_arg; 	unregister_net_sysctl_table(pernet->ctl_table_hdr); 	kfree(table);} #else static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet){	return 0;} static void mptcp_pernet_del_table(struct mptcp_pernet *pernet) {} #endif /* CONFIG_SYSCTL */ /* The following code block is to deal with middle box issues with MPTCP, * similar to what is done with TFO. * The proposed solution is to disable active MPTCP globally when SYN+MPC are * dropped, while SYN without MPC aren't. In this case, active side MPTCP is * disabled globally for 1hr at first. Then if it happens again, it is disabled * for 2h, then 4h, 8h, ... * The timeout is reset back to 1hr when a successful active MPTCP connection is * fully established. */ /* Disable active MPTCP and record current jiffies and active_disable_times */void mptcp_active_disable(struct sock *sk){	struct net *net = sock_net(sk);	struct mptcp_pernet *pernet; 	pernet = mptcp_get_pernet(net); 	if (!READ_ONCE(pernet->blackhole_timeout))		return; 	/* Paired with READ_ONCE() in mptcp_active_should_disable() */	WRITE_ONCE(pernet->active_disable_stamp, jiffies); 	/* Paired with smp_rmb() in mptcp_active_should_disable().	 * We want pernet->active_disable_stamp to be updated first.	 */	smp_mb__before_atomic();	atomic_inc(&pernet->active_disable_times); 	MPTCP_INC_STATS(net, MPTCP_MIB_BLACKHOLE);} /* Calculate timeout for MPTCP active disable * Return true if we are still in the active MPTCP disable period * Return false if timeout already expired and we should use active MPTCP */bool mptcp_active_should_disable(struct sock *ssk){	struct net *net = sock_net(ssk);	unsigned int blackhole_timeout;	struct mptcp_pernet *pernet;	unsigned long timeout;	int disable_times;	int multiplier; 	pernet = mptcp_get_pernet(net);	blackhole_timeout = READ_ONCE(pernet->blackhole_timeout); 	if (!blackhole_timeout)		return false; 	disable_times = atomic_read(&pernet->active_disable_times);	if (!disable_times)		return false; 	/* Paired with smp_mb__before_atomic() in mptcp_active_disable() */	smp_rmb(); 	/* Limit timeout to max: 2^6 * initial timeout */	multiplier = 1 << min(disable_times - 1, 6); 	/* Paired with the WRITE_ONCE() in mptcp_active_disable(). */	timeout = READ_ONCE(pernet->active_disable_stamp) +		  multiplier * blackhole_timeout * HZ; 	return time_before(jiffies, timeout);} /* Enable active MPTCP and reset active_disable_times if needed */void mptcp_active_enable(struct sock *sk){	struct mptcp_pernet *pernet = mptcp_get_pernet(sock_net(sk)); 	if (atomic_read(&pernet->active_disable_times)) {		struct dst_entry *dst = sk_dst_get(sk); 		if (dst && dst->dev && (dst->dev->flags & IFF_LOOPBACK))			atomic_set(&pernet->active_disable_times, 0);	}} /* Check the number of retransmissions, and fallback to TCP if needed */void mptcp_active_detect_blackhole(struct sock *ssk, bool expired){	struct mptcp_subflow_context *subflow;	u32 timeouts; 	if (!sk_is_mptcp(ssk))		return; 	timeouts = inet_csk(ssk)->icsk_retransmits;	subflow = mptcp_subflow_ctx(ssk); 	if (subflow->request_mptcp && ssk->sk_state == TCP_SYN_SENT) {		if (timeouts == 2 || (timeouts < 2 && expired)) {			MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPCAPABLEACTIVEDROP);			subflow->mpc_drop = 1;			mptcp_subflow_early_fallback(mptcp_sk(subflow->conn), subflow);		} else {			subflow->mpc_drop = 0;		}	}} static int __net_init mptcp_net_init(struct net *net){	struct mptcp_pernet *pernet = mptcp_get_pernet(net); 	mptcp_pernet_set_defaults(pernet); 	return mptcp_pernet_new_table(net, pernet);} /* Note: the callback will only be called per extra netns */static void __net_exit mptcp_net_exit(struct net *net){	struct mptcp_pernet *pernet = mptcp_get_pernet(net); 	mptcp_pernet_del_table(pernet);} static struct pernet_operations mptcp_pernet_ops = {	.init = mptcp_net_init,	.exit = mptcp_net_exit,	.id = &mptcp_pernet_id,	.size = sizeof(struct mptcp_pernet),}; void __init mptcp_init(void){	mptcp_join_cookie_init();	mptcp_proto_init(); 	if (register_pernet_subsys(&mptcp_pernet_ops) < 0)		panic("Failed to register MPTCP pernet subsystem.\n");} #if IS_ENABLED(CONFIG_MPTCP_IPV6)int __init mptcpv6_init(void){	int err; 	err = mptcp_proto_v6_init(); 	return err;}#endif