linux/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 <[email protected]>
 *       Christoph Paasch <[email protected]>
 *       Jaakko Korkeaniemi <[email protected]>
 *       Gregory Detal <[email protected]>
 *       Fabien Duchêne <[email protected]>
 *       Andreas Seelinger <[email protected]>
 *       Lavkesh Lahngir <[email protected]>
 *       Andreas Ripke <[email protected]>
 *       Vlad Dogaru <[email protected]>
 *       Octavian Purdila <[email protected]>
 *       John Ronan <[email protected]>
 *       Catalin Nicutar <[email protected]>
 *       Brandon Heller <[email protected]>
 */

#define pr_fmt(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 …

struct token_bucket { … };

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

static struct token_bucket *token_bucket(u32 token)
{ … }

/* called with bucket lock held */
static struct mptcp_subflow_request_sock *
__token_lookup_req(struct token_bucket *t, u32 token)
{ … }

/* called with bucket lock held */
static struct mptcp_sock *
__token_lookup_msk(struct token_bucket *t, u32 token)
{ … }

static bool __token_bucket_busy(struct token_bucket *t, u32 token)
{ … }

static void mptcp_crypto_key_gen_sha(u64 *key, u32 *token, u64 *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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

bool mptcp_token_exists(u32 token)
{ … }

/**
 * 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)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * 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)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * 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)
{ … }

/**
 * 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)
{ … }

void __init mptcp_token_init(void)
{ … }

#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