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-rw-r--r--net/mptcp/token.c195
1 files changed, 195 insertions, 0 deletions
diff --git a/net/mptcp/token.c b/net/mptcp/token.c
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+// 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/radix-tree.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"
+
+static RADIX_TREE(token_tree, GFP_ATOMIC);
+static RADIX_TREE(token_req_tree, GFP_ATOMIC);
+static DEFINE_SPINLOCK(token_tree_lock);
+static int token_used __read_mostly;
+
+/**
+ * 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);
+ int err;
+
+ while (1) {
+ u32 token;
+
+ mptcp_crypto_key_gen_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;
+ spin_lock_bh(&token_tree_lock);
+ if (!radix_tree_lookup(&token_req_tree, token) &&
+ !radix_tree_lookup(&token_tree, token))
+ break;
+ spin_unlock_bh(&token_tree_lock);
+ }
+
+ err = radix_tree_insert(&token_req_tree,
+ subflow_req->token, &token_used);
+ spin_unlock_bh(&token_tree_lock);
+ return err;
+}
+
+/**
+ * mptcp_token_new_connect - create new key/idsn/token for subflow
+ * @sk - 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 *sk)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ struct sock *mptcp_sock = subflow->conn;
+ int err;
+
+ while (1) {
+ u32 token;
+
+ mptcp_crypto_key_gen_sha(&subflow->local_key, &subflow->token,
+ &subflow->idsn);
+
+ pr_debug("ssk=%p, local_key=%llu, token=%u, idsn=%llu\n",
+ sk, subflow->local_key, subflow->token, subflow->idsn);
+
+ token = subflow->token;
+ spin_lock_bh(&token_tree_lock);
+ if (!radix_tree_lookup(&token_req_tree, token) &&
+ !radix_tree_lookup(&token_tree, token))
+ break;
+ spin_unlock_bh(&token_tree_lock);
+ }
+ err = radix_tree_insert(&token_tree, subflow->token, mptcp_sock);
+ spin_unlock_bh(&token_tree_lock);
+
+ return err;
+}
+
+/**
+ * mptcp_token_new_accept - insert token for later processing
+ * @token: the token to insert to the tree
+ *
+ * Called when a SYN packet creates a new logical connection, i.e.
+ * is not a join request.
+ *
+ * We don't have an mptcp socket yet at that point.
+ * This is paired with mptcp_token_update_accept, called on accept().
+ */
+int mptcp_token_new_accept(u32 token)
+{
+ int err;
+
+ spin_lock_bh(&token_tree_lock);
+ err = radix_tree_insert(&token_tree, token, &token_used);
+ spin_unlock_bh(&token_tree_lock);
+
+ return err;
+}
+
+/**
+ * mptcp_token_update_accept - update token to map to mptcp socket
+ * @conn: the new struct mptcp_sock
+ * @sk: the initial subflow for this mptcp socket
+ *
+ * Called when the first mptcp socket is created on accept to
+ * refresh the dummy mapping (done to reserve the token) with
+ * the mptcp_socket structure that wasn't allocated before.
+ */
+void mptcp_token_update_accept(struct sock *sk, struct sock *conn)
+{
+ struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+ void __rcu **slot;
+
+ spin_lock_bh(&token_tree_lock);
+ slot = radix_tree_lookup_slot(&token_tree, subflow->token);
+ WARN_ON_ONCE(!slot);
+ if (slot) {
+ WARN_ON_ONCE(rcu_access_pointer(*slot) != &token_used);
+ radix_tree_replace_slot(&token_tree, slot, conn);
+ }
+ spin_unlock_bh(&token_tree_lock);
+}
+
+/**
+ * mptcp_token_destroy_request - remove mptcp connection/token
+ * @token - token of mptcp connection to remove
+ *
+ * Remove not-yet-fully-established incoming connection identified
+ * by @token.
+ */
+void mptcp_token_destroy_request(u32 token)
+{
+ spin_lock_bh(&token_tree_lock);
+ radix_tree_delete(&token_req_tree, token);
+ spin_unlock_bh(&token_tree_lock);
+}
+
+/**
+ * mptcp_token_destroy - remove mptcp connection/token
+ * @token - token of mptcp connection to remove
+ *
+ * Remove the connection identified by @token.
+ */
+void mptcp_token_destroy(u32 token)
+{
+ spin_lock_bh(&token_tree_lock);
+ radix_tree_delete(&token_tree, token);
+ spin_unlock_bh(&token_tree_lock);
+}