1 files changed, 309 insertions, 88 deletions

diff --git a/net/mptcp/token.c b/net/mptcp/token.c
index 84d887806090..f52ee7b26aed 100644
--- a/net/mptcp/token.c
+++ b/net/mptcp/token.c
@@ -24,7 +24,7 @@
 
 #include <linux/kernel.h>
 #include <linux/module.h>
-#include <linux/radix-tree.h>
+#include <linux/memblock.h>
 #include <linux/ip.h>
 #include <linux/tcp.h>
 #include <net/sock.h>
@@ -33,14 +33,70 @@
 #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;
+#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
+ * @req: the request socket
  *
  * This function is called when a new mptcp connection is coming in.
  *
@@ -52,35 +108,33 @@ static int token_used __read_mostly;
 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);
+	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;
 	}
 
-	err = radix_tree_insert(&token_req_tree,
-				subflow_req->token, &token_used);
-	spin_unlock_bh(&token_tree_lock);
-	return err;
+	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
+ * @sk: the socket that will initiate a connection
  *
  * This function is called when a new outgoing mptcp connection is
  * initiated.
@@ -97,99 +151,266 @@ int mptcp_token_new_request(struct request_sock *req)
 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;
+	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
+	int retries = MPTCP_TOKEN_MAX_RETRIES;
+	struct token_bucket *bucket;
 
-		mptcp_crypto_key_gen_sha(&subflow->local_key, &subflow->token,
-					 &subflow->idsn);
+again:
+	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);
+	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;
 	}
-	err = radix_tree_insert(&token_tree, subflow->token, mptcp_sock);
-	spin_unlock_bh(&token_tree_lock);
 
-	return err;
+	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_new_accept - insert token for later processing
- * @token: the token to insert to the tree
+ * 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.
  *
- * We don't have an mptcp socket yet at that point.
- * This is paired with mptcp_token_update_accept, called on accept().
+ * returns NULL if no connection with the given token value exists.
  */
-int mptcp_token_new_accept(u32 token)
+struct mptcp_sock *mptcp_token_get_sock(struct net *net, u32 token)
 {
-	int err;
+	struct hlist_nulls_node *pos;
+	struct token_bucket *bucket;
+	struct mptcp_sock *msk;
+	struct sock *sk;
 
-	spin_lock_bh(&token_tree_lock);
-	err = radix_tree_insert(&token_tree, token, &token_used);
-	spin_unlock_bh(&token_tree_lock);
+	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;
 
-	return err;
+not_found:
+	msk = NULL;
+
+found:
+	rcu_read_unlock();
+	return msk;
 }
+EXPORT_SYMBOL_GPL(mptcp_token_get_sock);
 
 /**
- * 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
+ * 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.
  *
- * 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.
+ * On successful iteration, the iterator is move to the next position and the
+ * the acquires a reference to the returned socket.
  */
-void mptcp_token_update_accept(struct sock *sk, struct sock *conn)
+struct mptcp_sock *mptcp_token_iter_next(const struct net *net, long *s_slot,
+					 long *s_num)
 {
-	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);
+	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();
 	}
-	spin_unlock_bh(&token_tree_lock);
+
+out:
+	*s_slot = slot;
+	*s_num = num;
+	return ret;
 }
+EXPORT_SYMBOL_GPL(mptcp_token_iter_next);
 
 /**
  * mptcp_token_destroy_request - remove mptcp connection/token
- * @token - token of mptcp connection to remove
+ * @req: mptcp request socket dropping the token
  *
- * Remove not-yet-fully-established incoming connection identified
- * by @token.
+ * Remove the token associated to @req.
  */
-void mptcp_token_destroy_request(u32 token)
+void mptcp_token_destroy_request(struct request_sock *req)
 {
-	spin_lock_bh(&token_tree_lock);
-	radix_tree_delete(&token_req_tree, token);
-	spin_unlock_bh(&token_tree_lock);
+	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
- * @token - token of mptcp connection to remove
+ * @msk: mptcp connection dropping the token
  *
- * Remove the connection identified by @token.
+ * Remove the token associated to @msk
  */
-void mptcp_token_destroy(u32 token)
+void mptcp_token_destroy(struct mptcp_sock *msk)
 {
-	spin_lock_bh(&token_tree_lock);
-	radix_tree_delete(&token_tree, token);
-	spin_unlock_bh(&token_tree_lock);
+	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