[linux-block.git] / net / mptcp / token.c

// SPDX-License-Identifier: GPL-2.0
/* Multipath TCP token management
 * Copyright (c) 2017 - 2019, Intel Corporation.
 *
 * Note: This code is based on mptcp_ctrl.c from multipath-tcp.org,
 *       authored by:
 *
 *       Sébastien Barré <sebastien.barre@uclouvain.be>
 *       Christoph Paasch <christoph.paasch@uclouvain.be>
 *       Jaakko Korkeaniemi <jaakko.korkeaniemi@aalto.fi>
 *       Gregory Detal <gregory.detal@uclouvain.be>
 *       Fabien Duchêne <fabien.duchene@uclouvain.be>
 *       Andreas Seelinger <Andreas.Seelinger@rwth-aachen.de>
 *       Lavkesh Lahngir <lavkesh51@gmail.com>
 *       Andreas Ripke <ripke@neclab.eu>
 *       Vlad Dogaru <vlad.dogaru@intel.com>
 *       Octavian Purdila <octavian.purdila@intel.com>
 *       John Ronan <jronan@tssg.org>
 *       Catalin Nicutar <catalin.nicutar@gmail.com>
 *       Brandon Heller <brandonh@stanford.edu>
 */

#define pr_fmt(fmt) "MPTCP: " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/memblock.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <net/sock.h>
#include <net/inet_common.h>
#include <net/protocol.h>
#include <net/mptcp.h>
#include "protocol.h"

#define TOKEN_MAX_CHAIN_LEN	4

struct token_bucket {
	spinlock_t		lock;
	int			chain_len;
	struct hlist_nulls_head	req_chain;
	struct hlist_nulls_head	msk_chain;
};

static struct token_bucket *token_hash __read_mostly;
static unsigned int token_mask __read_mostly;

static struct token_bucket *token_bucket(u32 token)
{
	return &token_hash[token & token_mask];
}

/* called with bucket lock held */
static struct mptcp_subflow_request_sock *
__token_lookup_req(struct token_bucket *t, u32 token)
{
	struct mptcp_subflow_request_sock *req;
	struct hlist_nulls_node *pos;

	hlist_nulls_for_each_entry_rcu(req, pos, &t->req_chain, token_node)
		if (req->token == token)
			return req;
	return NULL;
}

/* called with bucket lock held */
static struct mptcp_sock *
__token_lookup_msk(struct token_bucket *t, u32 token)
{
	struct hlist_nulls_node *pos;
	struct sock *sk;

	sk_nulls_for_each_rcu(sk, pos, &t->msk_chain)
		if (mptcp_sk(sk)->token == token)
			return mptcp_sk(sk);
	return NULL;
}

static bool __token_bucket_busy(struct token_bucket *t, u32 token)
{
	return !token || t->chain_len >= TOKEN_MAX_CHAIN_LEN ||
	       __token_lookup_req(t, token) || __token_lookup_msk(t, token);
}

static void mptcp_crypto_key_gen_sha(u64 *key, u32 *token, u64 *idsn)
{
	/* we might consider a faster version that computes the key as a
	 * hash of some information available in the MPTCP socket. Use
	 * random data at the moment, as it's probably the safest option
	 * in case multiple sockets are opened in different namespaces at
	 * the same time.
	 */
	get_random_bytes(key, sizeof(u64));
	mptcp_crypto_key_sha(*key, token, idsn);
}

/**
 * mptcp_token_new_request - create new key/idsn/token for subflow_request
 * @req: the request socket
 *
 * This function is called when a new mptcp connection is coming in.
 *
 * It creates a unique token to identify the new mptcp connection,
 * a secret local key and the initial data sequence number (idsn).
 *
 * Returns 0 on success.
 */
int mptcp_token_new_request(struct request_sock *req)
{
	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
	struct token_bucket *bucket;
	u32 token;

	mptcp_crypto_key_sha(subflow_req->local_key,
			     &subflow_req->token,
			     &subflow_req->idsn);
	pr_debug("req=%p local_key=%llu, token=%u, idsn=%llu\n",
		 req, subflow_req->local_key, subflow_req->token,
		 subflow_req->idsn);

	token = subflow_req->token;
	bucket = token_bucket(token);
	spin_lock_bh(&bucket->lock);
	if (__token_bucket_busy(bucket, token)) {
		spin_unlock_bh(&bucket->lock);
		return -EBUSY;
	}

	hlist_nulls_add_head_rcu(&subflow_req->token_node, &bucket->req_chain);
	bucket->chain_len++;
	spin_unlock_bh(&bucket->lock);
	return 0;
}

/**
 * mptcp_token_new_connect - create new key/idsn/token for subflow
 * @ssk: the socket that will initiate a connection
 *
 * This function is called when a new outgoing mptcp connection is
 * initiated.
 *
 * It creates a unique token to identify the new mptcp connection,
 * a secret local key and the initial data sequence number (idsn).
 *
 * On success, the mptcp connection can be found again using
 * the computed token at a later time, this is needed to process
 * join requests.
 *
 * returns 0 on success.
 */
int mptcp_token_new_connect(struct sock *ssk)
{
	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
	int retries = MPTCP_TOKEN_MAX_RETRIES;
	struct sock *sk = subflow->conn;
	struct token_bucket *bucket;

again:
	mptcp_crypto_key_gen_sha(&subflow->local_key, &subflow->token,
				 &subflow->idsn);

	bucket = token_bucket(subflow->token);
	spin_lock_bh(&bucket->lock);
	if (__token_bucket_busy(bucket, subflow->token)) {
		spin_unlock_bh(&bucket->lock);
		if (!--retries)
			return -EBUSY;
		goto again;
	}

	pr_debug("ssk=%p, local_key=%llu, token=%u, idsn=%llu\n",
		 ssk, subflow->local_key, subflow->token, subflow->idsn);

	WRITE_ONCE(msk->token, subflow->token);
	__sk_nulls_add_node_rcu((struct sock *)msk, &bucket->msk_chain);
	bucket->chain_len++;
	spin_unlock_bh(&bucket->lock);
	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
	return 0;
}

/**
 * mptcp_token_accept - replace a req sk with full sock in token hash
 * @req: the request socket to be removed
 * @msk: the just cloned socket linked to the new connection
 *
 * Called when a SYN packet creates a new logical connection, i.e.
 * is not a join request.
 */
void mptcp_token_accept(struct mptcp_subflow_request_sock *req,
			struct mptcp_sock *msk)
{
	struct mptcp_subflow_request_sock *pos;
	struct sock *sk = (struct sock *)msk;
	struct token_bucket *bucket;

	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
	bucket = token_bucket(req->token);
	spin_lock_bh(&bucket->lock);

	/* pedantic lookup check for the moved token */
	pos = __token_lookup_req(bucket, req->token);
	if (!WARN_ON_ONCE(pos != req))
		hlist_nulls_del_init_rcu(&req->token_node);
	__sk_nulls_add_node_rcu((struct sock *)msk, &bucket->msk_chain);
	spin_unlock_bh(&bucket->lock);
}

bool mptcp_token_exists(u32 token)
{
	struct hlist_nulls_node *pos;
	struct token_bucket *bucket;
	struct mptcp_sock *msk;
	struct sock *sk;

	rcu_read_lock();
	bucket = token_bucket(token);

again:
	sk_nulls_for_each_rcu(sk, pos, &bucket->msk_chain) {
		msk = mptcp_sk(sk);
		if (READ_ONCE(msk->token) == token)
			goto found;
	}
	if (get_nulls_value(pos) != (token & token_mask))
		goto again;

	rcu_read_unlock();
	return false;
found:
	rcu_read_unlock();
	return true;
}

/**
 * mptcp_token_get_sock - retrieve mptcp connection sock using its token
 * @net: restrict to this namespace
 * @token: token of the mptcp connection to retrieve
 *
 * This function returns the mptcp connection structure with the given token.
 * A reference count on the mptcp socket returned is taken.
 *
 * returns NULL if no connection with the given token value exists.
 */
struct mptcp_sock *mptcp_token_get_sock(struct net *net, u32 token)
{
	struct hlist_nulls_node *pos;
	struct token_bucket *bucket;
	struct mptcp_sock *msk;
	struct sock *sk;

	rcu_read_lock();
	bucket = token_bucket(token);

again:
	sk_nulls_for_each_rcu(sk, pos, &bucket->msk_chain) {
		msk = mptcp_sk(sk);
		if (READ_ONCE(msk->token) != token ||
		    !net_eq(sock_net(sk), net))
			continue;

		if (!refcount_inc_not_zero(&sk->sk_refcnt))
			goto not_found;

		if (READ_ONCE(msk->token) != token ||
		    !net_eq(sock_net(sk), net)) {
			sock_put(sk);
			goto again;
		}
		goto found;
	}
	if (get_nulls_value(pos) != (token & token_mask))
		goto again;

not_found:
	msk = NULL;

found:
	rcu_read_unlock();
	return msk;
}
EXPORT_SYMBOL_GPL(mptcp_token_get_sock);

/**
 * mptcp_token_iter_next - iterate over the token container from given pos
 * @net: namespace to be iterated
 * @s_slot: start slot number
 * @s_num: start number inside the given lock
 *
 * This function returns the first mptcp connection structure found inside the
 * token container starting from the specified position, or NULL.
 *
 * On successful iteration, the iterator is moved to the next position and
 * a reference to the returned socket is acquired.
 */
struct mptcp_sock *mptcp_token_iter_next(const struct net *net, long *s_slot,
					 long *s_num)
{
	struct mptcp_sock *ret = NULL;
	struct hlist_nulls_node *pos;
	int slot, num = 0;

	for (slot = *s_slot; slot <= token_mask; *s_num = 0, slot++) {
		struct token_bucket *bucket = &token_hash[slot];
		struct sock *sk;

		num = 0;

		if (hlist_nulls_empty(&bucket->msk_chain))
			continue;

		rcu_read_lock();
		sk_nulls_for_each_rcu(sk, pos, &bucket->msk_chain) {
			++num;
			if (!net_eq(sock_net(sk), net))
				continue;

			if (num <= *s_num)
				continue;

			if (!refcount_inc_not_zero(&sk->sk_refcnt))
				continue;

			if (!net_eq(sock_net(sk), net)) {
				sock_put(sk);
				continue;
			}

			ret = mptcp_sk(sk);
			rcu_read_unlock();
			goto out;
		}
		rcu_read_unlock();
	}

out:
	*s_slot = slot;
	*s_num = num;
	return ret;
}
EXPORT_SYMBOL_GPL(mptcp_token_iter_next);

/**
 * mptcp_token_destroy_request - remove mptcp connection/token
 * @req: mptcp request socket dropping the token
 *
 * Remove the token associated to @req.
 */
void mptcp_token_destroy_request(struct request_sock *req)
{
	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
	struct mptcp_subflow_request_sock *pos;
	struct token_bucket *bucket;

	if (hlist_nulls_unhashed(&subflow_req->token_node))
		return;

	bucket = token_bucket(subflow_req->token);
	spin_lock_bh(&bucket->lock);
	pos = __token_lookup_req(bucket, subflow_req->token);
	if (!WARN_ON_ONCE(pos != subflow_req)) {
		hlist_nulls_del_init_rcu(&pos->token_node);
		bucket->chain_len--;
	}
	spin_unlock_bh(&bucket->lock);
}

/**
 * mptcp_token_destroy - remove mptcp connection/token
 * @msk: mptcp connection dropping the token
 *
 * Remove the token associated to @msk
 */
void mptcp_token_destroy(struct mptcp_sock *msk)
{
	struct sock *sk = (struct sock *)msk;
	struct token_bucket *bucket;
	struct mptcp_sock *pos;

	if (sk_unhashed((struct sock *)msk))
		return;

	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
	bucket = token_bucket(msk->token);
	spin_lock_bh(&bucket->lock);
	pos = __token_lookup_msk(bucket, msk->token);
	if (!WARN_ON_ONCE(pos != msk)) {
		__sk_nulls_del_node_init_rcu((struct sock *)pos);
		bucket->chain_len--;
	}
	spin_unlock_bh(&bucket->lock);
	WRITE_ONCE(msk->token, 0);
}

void __init mptcp_token_init(void)
{
	int i;

	token_hash = alloc_large_system_hash("MPTCP token",
					     sizeof(struct token_bucket),
					     0,
					     20,/* one slot per 1MB of memory */
					     HASH_ZERO,
					     NULL,
					     &token_mask,
					     0,
					     64 * 1024);
	for (i = 0; i < token_mask + 1; ++i) {
		INIT_HLIST_NULLS_HEAD(&token_hash[i].req_chain, i);
		INIT_HLIST_NULLS_HEAD(&token_hash[i].msk_chain, i);
		spin_lock_init(&token_hash[i].lock);
	}
}

#if IS_MODULE(CONFIG_MPTCP_KUNIT_TEST)
EXPORT_SYMBOL_GPL(mptcp_token_new_request);
EXPORT_SYMBOL_GPL(mptcp_token_new_connect);
EXPORT_SYMBOL_GPL(mptcp_token_accept);
EXPORT_SYMBOL_GPL(mptcp_token_destroy_request);
EXPORT_SYMBOL_GPL(mptcp_token_destroy);
#endif
Commit	Line	Data
79c0949e PK	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>
2c5ebd00	27	#include <linux/memblock.h>
79c0949e PK	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
2c5ebd00 PA	36	#define TOKEN_MAX_CHAIN_LEN 4
	37
	38	struct token_bucket {
	39	spinlock_t lock;
	40	int chain_len;
	41	struct hlist_nulls_head req_chain;
	42	struct hlist_nulls_head msk_chain;
	43	};
	44
	45	static struct token_bucket *token_hash __read_mostly;
	46	static unsigned int token_mask __read_mostly;
	47
	48	static struct token_bucket *token_bucket(u32 token)
	49	{
	50	return &token_hash[token & token_mask];
	51	}
	52
	53	/* called with bucket lock held */
	54	static struct mptcp_subflow_request_sock *
	55	__token_lookup_req(struct token_bucket *t, u32 token)
	56	{
	57	struct mptcp_subflow_request_sock *req;
	58	struct hlist_nulls_node *pos;
	59
	60	hlist_nulls_for_each_entry_rcu(req, pos, &t->req_chain, token_node)
	61	if (req->token == token)
	62	return req;
	63	return NULL;
	64	}
	65
	66	/* called with bucket lock held */
	67	static struct mptcp_sock *
	68	__token_lookup_msk(struct token_bucket *t, u32 token)
	69	{
	70	struct hlist_nulls_node *pos;
	71	struct sock *sk;
	72
	73	sk_nulls_for_each_rcu(sk, pos, &t->msk_chain)
	74	if (mptcp_sk(sk)->token == token)
	75	return mptcp_sk(sk);
	76	return NULL;
	77	}
	78
	79	static bool __token_bucket_busy(struct token_bucket *t, u32 token)
	80	{
	81	return !token \|\| t->chain_len >= TOKEN_MAX_CHAIN_LEN \|\|
	82	__token_lookup_req(t, token) \|\| __token_lookup_msk(t, token);
	83	}
79c0949e	84
c1d069e3 FW	85	static void mptcp_crypto_key_gen_sha(u64 key, u32 token, u64 *idsn)
	86	{
	87	/* we might consider a faster version that computes the key as a
	88	* hash of some information available in the MPTCP socket. Use
	89	* random data at the moment, as it's probably the safest option
	90	* in case multiple sockets are opened in different namespaces at
	91	* the same time.
	92	*/
	93	get_random_bytes(key, sizeof(u64));
	94	mptcp_crypto_key_sha(*key, token, idsn);
	95	}
	96
79c0949e PK	97	/**
79c0949e PK	98	* mptcp_token_new_request - create new key/idsn/token for subflow_request
564cf2f3	99	* @req: the request socket
79c0949e PK	100	*
	101	* This function is called when a new mptcp connection is coming in.
	102	*
	103	* It creates a unique token to identify the new mptcp connection,
	104	* a secret local key and the initial data sequence number (idsn).
	105	*
	106	* Returns 0 on success.
	107	*/
	108	int mptcp_token_new_request(struct request_sock *req)
	109	{
	110	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
2c5ebd00 PA	111	struct token_bucket *bucket;
	112	u32 token;
	113
535fb815 FW	114	mptcp_crypto_key_sha(subflow_req->local_key,
	115	&subflow_req->token,
	116	&subflow_req->idsn);
2c5ebd00 PA	117	pr_debug("req=%p local_key=%llu, token=%u, idsn=%llu\n",
	118	req, subflow_req->local_key, subflow_req->token,
	119	subflow_req->idsn);
	120
	121	token = subflow_req->token;
	122	bucket = token_bucket(token);
	123	spin_lock_bh(&bucket->lock);
	124	if (__token_bucket_busy(bucket, token)) {
	125	spin_unlock_bh(&bucket->lock);
535fb815	126	return -EBUSY;
79c0949e PK	127	}
79c0949e PK	128
2c5ebd00 PA	129	hlist_nulls_add_head_rcu(&subflow_req->token_node, &bucket->req_chain);
	130	bucket->chain_len++;
	131	spin_unlock_bh(&bucket->lock);
	132	return 0;
79c0949e PK	133	}
	134
	135	/**
	136	* mptcp_token_new_connect - create new key/idsn/token for subflow
294de909	137	* @ssk: the socket that will initiate a connection
79c0949e PK	138	*
	139	* This function is called when a new outgoing mptcp connection is
	140	* initiated.
	141	*
	142	* It creates a unique token to identify the new mptcp connection,
	143	* a secret local key and the initial data sequence number (idsn).
	144	*
	145	* On success, the mptcp connection can be found again using
	146	* the computed token at a later time, this is needed to process
	147	* join requests.
	148	*
	149	* returns 0 on success.
	150	*/
294de909	151	int mptcp_token_new_connect(struct sock *ssk)
79c0949e	152	{
294de909	153	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
2c5ebd00	154	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
c68a0cd1	155	int retries = MPTCP_TOKEN_MAX_RETRIES;
c558246e	156	struct sock *sk = subflow->conn;
2c5ebd00	157	struct token_bucket *bucket;
79c0949e	158
2c5ebd00 PA	159	again:
	160	mptcp_crypto_key_gen_sha(&subflow->local_key, &subflow->token,
	161	&subflow->idsn);
79c0949e	162
2c5ebd00 PA	163	bucket = token_bucket(subflow->token);
	164	spin_lock_bh(&bucket->lock);
	165	if (__token_bucket_busy(bucket, subflow->token)) {
	166	spin_unlock_bh(&bucket->lock);
	167	if (!--retries)
	168	return -EBUSY;
	169	goto again;
79c0949e	170	}
79c0949e	171
2f1af441	172	pr_debug("ssk=%p, local_key=%llu, token=%u, idsn=%llu\n",
294de909	173	ssk, subflow->local_key, subflow->token, subflow->idsn);
2f1af441	174
2c5ebd00 PA	175	WRITE_ONCE(msk->token, subflow->token);
	176	__sk_nulls_add_node_rcu((struct sock *)msk, &bucket->msk_chain);
	177	bucket->chain_len++;
	178	spin_unlock_bh(&bucket->lock);
c558246e	179	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
2c5ebd00	180	return 0;
79c0949e PK	181	}
	182
	183	/**
2c5ebd00 PA	184	* mptcp_token_accept - replace a req sk with full sock in token hash
	185	* @req: the request socket to be removed
	186	* @msk: the just cloned socket linked to the new connection
79c0949e PK	187	*
	188	* Called when a SYN packet creates a new logical connection, i.e.
	189	* is not a join request.
79c0949e	190	*/
2c5ebd00 PA	191	void mptcp_token_accept(struct mptcp_subflow_request_sock *req,
2c5ebd00 PA	192	struct mptcp_sock *msk)
79c0949e	193	{
2c5ebd00	194	struct mptcp_subflow_request_sock *pos;
c558246e	195	struct sock sk = (struct sock )msk;
2c5ebd00	196	struct token_bucket *bucket;
79c0949e	197
c558246e	198	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
2c5ebd00 PA	199	bucket = token_bucket(req->token);
2c5ebd00 PA	200	spin_lock_bh(&bucket->lock);
79c0949e	201
2c5ebd00 PA	202	/* pedantic lookup check for the moved token */
	203	pos = __token_lookup_req(bucket, req->token);
	204	if (!WARN_ON_ONCE(pos != req))
	205	hlist_nulls_del_init_rcu(&req->token_node);
	206	__sk_nulls_add_node_rcu((struct sock *)msk, &bucket->msk_chain);
	207	spin_unlock_bh(&bucket->lock);
79c0949e PK	208	}
79c0949e PK	209
c83a47e5 FW	210	bool mptcp_token_exists(u32 token)
	211	{
	212	struct hlist_nulls_node *pos;
	213	struct token_bucket *bucket;
	214	struct mptcp_sock *msk;
	215	struct sock *sk;
	216
	217	rcu_read_lock();
	218	bucket = token_bucket(token);
	219
	220	again:
	221	sk_nulls_for_each_rcu(sk, pos, &bucket->msk_chain) {
	222	msk = mptcp_sk(sk);
	223	if (READ_ONCE(msk->token) == token)
	224	goto found;
	225	}
	226	if (get_nulls_value(pos) != (token & token_mask))
	227	goto again;
	228
	229	rcu_read_unlock();
	230	return false;
	231	found:
	232	rcu_read_unlock();
	233	return true;
	234	}
	235
f296234c PK	236	/**
f296234c PK	237	* mptcp_token_get_sock - retrieve mptcp connection sock using its token
ea1300b9	238	* @net: restrict to this namespace
f296234c PK	239	* @token: token of the mptcp connection to retrieve
	240	*
	241	* This function returns the mptcp connection structure with the given token.
	242	* A reference count on the mptcp socket returned is taken.
	243	*
	244	* returns NULL if no connection with the given token value exists.
	245	*/
ea1300b9	246	struct mptcp_sock mptcp_token_get_sock(struct net net, u32 token)
f296234c	247	{
2c5ebd00 PA	248	struct hlist_nulls_node *pos;
	249	struct token_bucket *bucket;
	250	struct mptcp_sock *msk;
	251	struct sock *sk;
	252
	253	rcu_read_lock();
	254	bucket = token_bucket(token);
	255
	256	again:
	257	sk_nulls_for_each_rcu(sk, pos, &bucket->msk_chain) {
	258	msk = mptcp_sk(sk);
ea1300b9 FW	259	if (READ_ONCE(msk->token) != token \|\|
ea1300b9 FW	260	!net_eq(sock_net(sk), net))
2c5ebd00	261	continue;
ea1300b9	262
2c5ebd00 PA	263	if (!refcount_inc_not_zero(&sk->sk_refcnt))
2c5ebd00 PA	264	goto not_found;
ea1300b9 FW	265
	266	if (READ_ONCE(msk->token) != token \|\|
	267	!net_eq(sock_net(sk), net)) {
2c5ebd00 PA	268	sock_put(sk);
	269	goto again;
	270	}
	271	goto found;
f296234c	272	}
2c5ebd00 PA	273	if (get_nulls_value(pos) != (token & token_mask))
	274	goto again;
	275
	276	not_found:
	277	msk = NULL;
f296234c	278
2c5ebd00 PA	279	found:
	280	rcu_read_unlock();
	281	return msk;
f296234c	282	}
96d890da PA	283	EXPORT_SYMBOL_GPL(mptcp_token_get_sock);
	284
	285	/**
	286	* mptcp_token_iter_next - iterate over the token container from given pos
	287	* @net: namespace to be iterated
	288	* @s_slot: start slot number
	289	* @s_num: start number inside the given lock
	290	*
	291	* This function returns the first mptcp connection structure found inside the
	292	* token container starting from the specified position, or NULL.
	293	*
4373bf4b MM	294	* On successful iteration, the iterator is moved to the next position and
4373bf4b MM	295	* a reference to the returned socket is acquired.
96d890da PA	296	*/
	297	struct mptcp_sock mptcp_token_iter_next(const struct net net, long *s_slot,
	298	long *s_num)
	299	{
	300	struct mptcp_sock *ret = NULL;
	301	struct hlist_nulls_node *pos;
e16b874e	302	int slot, num = 0;
96d890da PA	303
	304	for (slot = s_slot; slot <= token_mask; s_num = 0, slot++) {
	305	struct token_bucket *bucket = &token_hash[slot];
	306	struct sock *sk;
	307
	308	num = 0;
	309
	310	if (hlist_nulls_empty(&bucket->msk_chain))
	311	continue;
	312
	313	rcu_read_lock();
	314	sk_nulls_for_each_rcu(sk, pos, &bucket->msk_chain) {
	315	++num;
	316	if (!net_eq(sock_net(sk), net))
	317	continue;
	318
	319	if (num <= *s_num)
	320	continue;
	321
	322	if (!refcount_inc_not_zero(&sk->sk_refcnt))
	323	continue;
	324
	325	if (!net_eq(sock_net(sk), net)) {
	326	sock_put(sk);
	327	continue;
	328	}
	329
	330	ret = mptcp_sk(sk);
	331	rcu_read_unlock();
	332	goto out;
	333	}
	334	rcu_read_unlock();
	335	}
	336
	337	out:
	338	*s_slot = slot;
	339	*s_num = num;
	340	return ret;
	341	}
	342	EXPORT_SYMBOL_GPL(mptcp_token_iter_next);
f296234c	343
79c0949e PK	344	/**
79c0949e PK	345	* mptcp_token_destroy_request - remove mptcp connection/token
2c5ebd00	346	* @req: mptcp request socket dropping the token
79c0949e	347	*
2c5ebd00	348	* Remove the token associated to @req.
79c0949e	349	*/
2c5ebd00	350	void mptcp_token_destroy_request(struct request_sock *req)
79c0949e	351	{
2c5ebd00 PA	352	struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
	353	struct mptcp_subflow_request_sock *pos;
	354	struct token_bucket *bucket;
	355
	356	if (hlist_nulls_unhashed(&subflow_req->token_node))
	357	return;
	358
	359	bucket = token_bucket(subflow_req->token);
	360	spin_lock_bh(&bucket->lock);
	361	pos = __token_lookup_req(bucket, subflow_req->token);
	362	if (!WARN_ON_ONCE(pos != subflow_req)) {
	363	hlist_nulls_del_init_rcu(&pos->token_node);
	364	bucket->chain_len--;
	365	}
	366	spin_unlock_bh(&bucket->lock);
79c0949e PK	367	}
	368
	369	/**
	370	* mptcp_token_destroy - remove mptcp connection/token
2c5ebd00	371	* @msk: mptcp connection dropping the token
79c0949e	372	*
2c5ebd00	373	* Remove the token associated to @msk
79c0949e	374	*/
2c5ebd00	375	void mptcp_token_destroy(struct mptcp_sock *msk)
79c0949e	376	{
c558246e	377	struct sock sk = (struct sock )msk;
2c5ebd00 PA	378	struct token_bucket *bucket;
	379	struct mptcp_sock *pos;
	380
	381	if (sk_unhashed((struct sock *)msk))
	382	return;
	383
c558246e	384	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
2c5ebd00 PA	385	bucket = token_bucket(msk->token);
	386	spin_lock_bh(&bucket->lock);
	387	pos = __token_lookup_msk(bucket, msk->token);
	388	if (!WARN_ON_ONCE(pos != msk)) {
	389	__sk_nulls_del_node_init_rcu((struct sock *)pos);
	390	bucket->chain_len--;
	391	}
	392	spin_unlock_bh(&bucket->lock);
b29fcfb5	393	WRITE_ONCE(msk->token, 0);
2c5ebd00 PA	394	}
	395
	396	void __init mptcp_token_init(void)
	397	{
	398	int i;
	399
	400	token_hash = alloc_large_system_hash("MPTCP token",
	401	sizeof(struct token_bucket),
	402	0,
	403	20,/* one slot per 1MB of memory */
6ab301c9	404	HASH_ZERO,
2c5ebd00 PA	405	NULL,
	406	&token_mask,
	407	0,
	408	64 * 1024);
	409	for (i = 0; i < token_mask + 1; ++i) {
	410	INIT_HLIST_NULLS_HEAD(&token_hash[i].req_chain, i);
	411	INIT_HLIST_NULLS_HEAD(&token_hash[i].msk_chain, i);
	412	spin_lock_init(&token_hash[i].lock);
	413	}
79c0949e	414	}
a8ee9c9b	415
3fcc8a25	416	#if IS_MODULE(CONFIG_MPTCP_KUNIT_TEST)
a8ee9c9b PA	417	EXPORT_SYMBOL_GPL(mptcp_token_new_request);
	418	EXPORT_SYMBOL_GPL(mptcp_token_new_connect);
	419	EXPORT_SYMBOL_GPL(mptcp_token_accept);
a8ee9c9b PA	420	EXPORT_SYMBOL_GPL(mptcp_token_destroy_request);
	421	EXPORT_SYMBOL_GPL(mptcp_token_destroy);
	422	#endif