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b29fcfb54c
The current mptcp_disconnect() implementation lacks several steps, we additionally need to reset the msk socket state and flush the subflow list. Factor out the needed helper to avoid code duplication. Additionally ensure that the initial subflow is disposed only after mptcp_close(), just reset it at disconnect time. Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
417 lines
11 KiB
C
417 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Multipath TCP token management
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* Copyright (c) 2017 - 2019, Intel Corporation.
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*
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* Note: This code is based on mptcp_ctrl.c from multipath-tcp.org,
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* authored by:
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*
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* Sébastien Barré <sebastien.barre@uclouvain.be>
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* Christoph Paasch <christoph.paasch@uclouvain.be>
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* Jaakko Korkeaniemi <jaakko.korkeaniemi@aalto.fi>
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* Gregory Detal <gregory.detal@uclouvain.be>
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* Fabien Duchêne <fabien.duchene@uclouvain.be>
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* Andreas Seelinger <Andreas.Seelinger@rwth-aachen.de>
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* Lavkesh Lahngir <lavkesh51@gmail.com>
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* Andreas Ripke <ripke@neclab.eu>
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* Vlad Dogaru <vlad.dogaru@intel.com>
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* Octavian Purdila <octavian.purdila@intel.com>
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* John Ronan <jronan@tssg.org>
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* Catalin Nicutar <catalin.nicutar@gmail.com>
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* Brandon Heller <brandonh@stanford.edu>
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*/
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#define pr_fmt(fmt) "MPTCP: " fmt
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/memblock.h>
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#include <linux/ip.h>
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#include <linux/tcp.h>
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#include <net/sock.h>
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#include <net/inet_common.h>
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#include <net/protocol.h>
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#include <net/mptcp.h>
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#include "protocol.h"
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#define TOKEN_MAX_CHAIN_LEN 4
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struct token_bucket {
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spinlock_t lock;
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int chain_len;
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struct hlist_nulls_head req_chain;
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struct hlist_nulls_head msk_chain;
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};
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static struct token_bucket *token_hash __read_mostly;
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static unsigned int token_mask __read_mostly;
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static struct token_bucket *token_bucket(u32 token)
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{
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return &token_hash[token & token_mask];
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}
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/* called with bucket lock held */
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static struct mptcp_subflow_request_sock *
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__token_lookup_req(struct token_bucket *t, u32 token)
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{
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struct mptcp_subflow_request_sock *req;
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struct hlist_nulls_node *pos;
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hlist_nulls_for_each_entry_rcu(req, pos, &t->req_chain, token_node)
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if (req->token == token)
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return req;
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return NULL;
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}
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/* called with bucket lock held */
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static struct mptcp_sock *
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__token_lookup_msk(struct token_bucket *t, u32 token)
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{
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struct hlist_nulls_node *pos;
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struct sock *sk;
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sk_nulls_for_each_rcu(sk, pos, &t->msk_chain)
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if (mptcp_sk(sk)->token == token)
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return mptcp_sk(sk);
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return NULL;
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}
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static bool __token_bucket_busy(struct token_bucket *t, u32 token)
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{
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return !token || t->chain_len >= TOKEN_MAX_CHAIN_LEN ||
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__token_lookup_req(t, token) || __token_lookup_msk(t, token);
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}
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static void mptcp_crypto_key_gen_sha(u64 *key, u32 *token, u64 *idsn)
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{
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/* we might consider a faster version that computes the key as a
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* hash of some information available in the MPTCP socket. Use
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* random data at the moment, as it's probably the safest option
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* in case multiple sockets are opened in different namespaces at
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* the same time.
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*/
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get_random_bytes(key, sizeof(u64));
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mptcp_crypto_key_sha(*key, token, idsn);
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}
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/**
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* mptcp_token_new_request - create new key/idsn/token for subflow_request
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* @req: the request socket
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*
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* This function is called when a new mptcp connection is coming in.
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*
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* It creates a unique token to identify the new mptcp connection,
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* a secret local key and the initial data sequence number (idsn).
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*
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* Returns 0 on success.
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*/
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int mptcp_token_new_request(struct request_sock *req)
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{
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struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
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struct token_bucket *bucket;
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u32 token;
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mptcp_crypto_key_sha(subflow_req->local_key,
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&subflow_req->token,
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&subflow_req->idsn);
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pr_debug("req=%p local_key=%llu, token=%u, idsn=%llu\n",
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req, subflow_req->local_key, subflow_req->token,
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subflow_req->idsn);
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token = subflow_req->token;
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bucket = token_bucket(token);
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spin_lock_bh(&bucket->lock);
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if (__token_bucket_busy(bucket, token)) {
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spin_unlock_bh(&bucket->lock);
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return -EBUSY;
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}
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hlist_nulls_add_head_rcu(&subflow_req->token_node, &bucket->req_chain);
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bucket->chain_len++;
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spin_unlock_bh(&bucket->lock);
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return 0;
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}
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/**
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* mptcp_token_new_connect - create new key/idsn/token for subflow
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* @sk: the socket that will initiate a connection
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*
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* This function is called when a new outgoing mptcp connection is
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* initiated.
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*
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* It creates a unique token to identify the new mptcp connection,
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* a secret local key and the initial data sequence number (idsn).
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*
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* On success, the mptcp connection can be found again using
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* the computed token at a later time, this is needed to process
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* join requests.
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*
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* returns 0 on success.
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*/
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int mptcp_token_new_connect(struct sock *sk)
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{
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struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
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struct mptcp_sock *msk = mptcp_sk(subflow->conn);
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int retries = MPTCP_TOKEN_MAX_RETRIES;
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struct token_bucket *bucket;
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again:
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mptcp_crypto_key_gen_sha(&subflow->local_key, &subflow->token,
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&subflow->idsn);
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bucket = token_bucket(subflow->token);
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spin_lock_bh(&bucket->lock);
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if (__token_bucket_busy(bucket, subflow->token)) {
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spin_unlock_bh(&bucket->lock);
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if (!--retries)
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return -EBUSY;
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goto again;
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}
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pr_debug("ssk=%p, local_key=%llu, token=%u, idsn=%llu\n",
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sk, subflow->local_key, subflow->token, subflow->idsn);
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WRITE_ONCE(msk->token, subflow->token);
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__sk_nulls_add_node_rcu((struct sock *)msk, &bucket->msk_chain);
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bucket->chain_len++;
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spin_unlock_bh(&bucket->lock);
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return 0;
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}
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/**
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* mptcp_token_accept - replace a req sk with full sock in token hash
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* @req: the request socket to be removed
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* @msk: the just cloned socket linked to the new connection
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*
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* Called when a SYN packet creates a new logical connection, i.e.
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* is not a join request.
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*/
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void mptcp_token_accept(struct mptcp_subflow_request_sock *req,
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struct mptcp_sock *msk)
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{
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struct mptcp_subflow_request_sock *pos;
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struct token_bucket *bucket;
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bucket = token_bucket(req->token);
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spin_lock_bh(&bucket->lock);
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/* pedantic lookup check for the moved token */
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pos = __token_lookup_req(bucket, req->token);
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if (!WARN_ON_ONCE(pos != req))
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hlist_nulls_del_init_rcu(&req->token_node);
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__sk_nulls_add_node_rcu((struct sock *)msk, &bucket->msk_chain);
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spin_unlock_bh(&bucket->lock);
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}
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bool mptcp_token_exists(u32 token)
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{
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struct hlist_nulls_node *pos;
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struct token_bucket *bucket;
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struct mptcp_sock *msk;
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struct sock *sk;
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rcu_read_lock();
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bucket = token_bucket(token);
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again:
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sk_nulls_for_each_rcu(sk, pos, &bucket->msk_chain) {
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msk = mptcp_sk(sk);
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if (READ_ONCE(msk->token) == token)
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goto found;
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}
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if (get_nulls_value(pos) != (token & token_mask))
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goto again;
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rcu_read_unlock();
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return false;
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found:
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rcu_read_unlock();
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return true;
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}
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/**
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* mptcp_token_get_sock - retrieve mptcp connection sock using its token
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* @net: restrict to this namespace
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* @token: token of the mptcp connection to retrieve
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*
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* This function returns the mptcp connection structure with the given token.
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* A reference count on the mptcp socket returned is taken.
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*
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* returns NULL if no connection with the given token value exists.
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*/
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struct mptcp_sock *mptcp_token_get_sock(struct net *net, u32 token)
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{
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struct hlist_nulls_node *pos;
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struct token_bucket *bucket;
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struct mptcp_sock *msk;
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struct sock *sk;
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rcu_read_lock();
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bucket = token_bucket(token);
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again:
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sk_nulls_for_each_rcu(sk, pos, &bucket->msk_chain) {
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msk = mptcp_sk(sk);
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if (READ_ONCE(msk->token) != token ||
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!net_eq(sock_net(sk), net))
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continue;
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if (!refcount_inc_not_zero(&sk->sk_refcnt))
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goto not_found;
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if (READ_ONCE(msk->token) != token ||
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!net_eq(sock_net(sk), net)) {
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sock_put(sk);
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goto again;
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}
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goto found;
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}
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if (get_nulls_value(pos) != (token & token_mask))
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goto again;
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not_found:
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msk = NULL;
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found:
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rcu_read_unlock();
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return msk;
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}
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EXPORT_SYMBOL_GPL(mptcp_token_get_sock);
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/**
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* mptcp_token_iter_next - iterate over the token container from given pos
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* @net: namespace to be iterated
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* @s_slot: start slot number
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* @s_num: start number inside the given lock
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*
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* This function returns the first mptcp connection structure found inside the
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* token container starting from the specified position, or NULL.
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*
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* On successful iteration, the iterator is move to the next position and the
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* the acquires a reference to the returned socket.
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*/
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struct mptcp_sock *mptcp_token_iter_next(const struct net *net, long *s_slot,
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long *s_num)
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{
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struct mptcp_sock *ret = NULL;
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struct hlist_nulls_node *pos;
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int slot, num = 0;
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for (slot = *s_slot; slot <= token_mask; *s_num = 0, slot++) {
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struct token_bucket *bucket = &token_hash[slot];
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struct sock *sk;
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num = 0;
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if (hlist_nulls_empty(&bucket->msk_chain))
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continue;
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rcu_read_lock();
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sk_nulls_for_each_rcu(sk, pos, &bucket->msk_chain) {
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++num;
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if (!net_eq(sock_net(sk), net))
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continue;
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if (num <= *s_num)
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continue;
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if (!refcount_inc_not_zero(&sk->sk_refcnt))
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continue;
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if (!net_eq(sock_net(sk), net)) {
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sock_put(sk);
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continue;
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}
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ret = mptcp_sk(sk);
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rcu_read_unlock();
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goto out;
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}
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rcu_read_unlock();
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}
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out:
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*s_slot = slot;
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*s_num = num;
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return ret;
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}
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EXPORT_SYMBOL_GPL(mptcp_token_iter_next);
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/**
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* mptcp_token_destroy_request - remove mptcp connection/token
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* @req: mptcp request socket dropping the token
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*
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* Remove the token associated to @req.
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*/
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void mptcp_token_destroy_request(struct request_sock *req)
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{
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struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
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struct mptcp_subflow_request_sock *pos;
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struct token_bucket *bucket;
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if (hlist_nulls_unhashed(&subflow_req->token_node))
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return;
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bucket = token_bucket(subflow_req->token);
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spin_lock_bh(&bucket->lock);
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pos = __token_lookup_req(bucket, subflow_req->token);
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if (!WARN_ON_ONCE(pos != subflow_req)) {
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hlist_nulls_del_init_rcu(&pos->token_node);
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bucket->chain_len--;
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}
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spin_unlock_bh(&bucket->lock);
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}
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/**
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* mptcp_token_destroy - remove mptcp connection/token
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* @msk: mptcp connection dropping the token
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*
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* Remove the token associated to @msk
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*/
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void mptcp_token_destroy(struct mptcp_sock *msk)
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{
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struct token_bucket *bucket;
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struct mptcp_sock *pos;
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if (sk_unhashed((struct sock *)msk))
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return;
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bucket = token_bucket(msk->token);
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spin_lock_bh(&bucket->lock);
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pos = __token_lookup_msk(bucket, msk->token);
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if (!WARN_ON_ONCE(pos != msk)) {
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__sk_nulls_del_node_init_rcu((struct sock *)pos);
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bucket->chain_len--;
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}
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spin_unlock_bh(&bucket->lock);
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WRITE_ONCE(msk->token, 0);
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}
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void __init mptcp_token_init(void)
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{
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int i;
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token_hash = alloc_large_system_hash("MPTCP token",
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sizeof(struct token_bucket),
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0,
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20,/* one slot per 1MB of memory */
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HASH_ZERO,
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NULL,
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&token_mask,
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0,
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64 * 1024);
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for (i = 0; i < token_mask + 1; ++i) {
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INIT_HLIST_NULLS_HEAD(&token_hash[i].req_chain, i);
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INIT_HLIST_NULLS_HEAD(&token_hash[i].msk_chain, i);
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spin_lock_init(&token_hash[i].lock);
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}
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}
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#if IS_MODULE(CONFIG_MPTCP_KUNIT_TEST)
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EXPORT_SYMBOL_GPL(mptcp_token_new_request);
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EXPORT_SYMBOL_GPL(mptcp_token_new_connect);
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EXPORT_SYMBOL_GPL(mptcp_token_accept);
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EXPORT_SYMBOL_GPL(mptcp_token_destroy_request);
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EXPORT_SYMBOL_GPL(mptcp_token_destroy);
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#endif
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