mptcp: add a new helper subflow_req_create_thmac

This patch adds a new helper named subflow_req_create_thmac, which is
extracted from subflow_token_join_request. It initializes subflow_req's
local_nonce and thmac fields, those are the more expensive to populate.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 2dcc0fb..94926ab 100644 (file)
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -64,10 +64,23 @@ static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk)
 }
 
 /* validate received token and create truncated hmac and nonce for SYN-ACK */
+static void subflow_req_create_thmac(struct mptcp_subflow_request_sock *subflow_req)
+{
+       struct mptcp_sock *msk = subflow_req->msk;
+       u8 hmac[SHA256_DIGEST_SIZE];
+
+       get_random_bytes(&subflow_req->local_nonce, sizeof(u32));
+
+       subflow_generate_hmac(msk->local_key, msk->remote_key,
+                             subflow_req->local_nonce,
+                             subflow_req->remote_nonce, hmac);
+
+       subflow_req->thmac = get_unaligned_be64(hmac);
+}
+
 static struct mptcp_sock *subflow_token_join_request(struct request_sock *req)
 {
        struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
-       u8 hmac[SHA256_DIGEST_SIZE];
        struct mptcp_sock *msk;
        int local_id;
 
@@ -84,13 +97,6 @@ static struct mptcp_sock *subflow_token_join_request(struct request_sock *req)
        }
        subflow_req->local_id = local_id;
 
-       get_random_bytes(&subflow_req->local_nonce, sizeof(u32));
-
-       subflow_generate_hmac(msk->local_key, msk->remote_key,
-                             subflow_req->local_nonce,
-                             subflow_req->remote_nonce, hmac);
-
-       subflow_req->thmac = get_unaligned_be64(hmac);
        return msk;
 }
 
@@ -186,6 +192,8 @@ again:
                if (!subflow_req->msk)
                        return -EPERM;
 
+               subflow_req_create_thmac(subflow_req);
+
                if (unlikely(req->syncookie)) {
                        if (mptcp_can_accept_new_subflow(subflow_req->msk))
                                subflow_init_req_cookie_join_save(subflow_req, skb);