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-rw-r--r--net/mptcp/token.c416
1 files changed, 416 insertions, 0 deletions
diff --git a/net/mptcp/token.c b/net/mptcp/token.c
new file mode 100644
index 000000000..f52ee7b26
--- /dev/null
+++ b/net/mptcp/token.c
@@ -0,0 +1,416 @@
+// 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
+ * @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 mptcp_sock *msk = mptcp_sk(subflow->conn);
+ int retries = MPTCP_TOKEN_MAX_RETRIES;
+ 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",
+ sk, 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);
+ 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 token_bucket *bucket;
+
+ 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 move to the next position and the
+ * the acquires a reference to the returned socket.
+ */
+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 token_bucket *bucket;
+ struct mptcp_sock *pos;
+
+ if (sk_unhashed((struct sock *)msk))
+ return;
+
+ 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
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