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