netdev - [PATCH v2 5/6] net/handshake: Unpin sock->file if a handshake is cancelled

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Date: Fri, 05 May 2023 20:47:13 -0400
From: Chuck Lever <cel@...nel.org>
To: kernel-tls-handshake@...ts.linux.dev
Cc: netdev@...r.kernel.org, dan.carpenter@...aro.org
Subject: [PATCH v2 5/6] net/handshake: Unpin sock->file if a handshake is
 cancelled

From: Chuck Lever <chuck.lever@...cle.com>

If user space never calls DONE, sock->file's reference count remains
elevated. Enable sock->file to be freed eventually in this case.

Reported-by: Jakub Kacinski <kuba@...nel.org>
Fixes: 3b3009ea8abb ("net/handshake: Create a NETLINK service for handling handshake requests")
Signed-off-by: Chuck Lever <chuck.lever@...cle.com>
---
 net/handshake/handshake.h |    1 +
 net/handshake/request.c   |    4 ++++
 2 files changed, 5 insertions(+)

diff --git a/net/handshake/handshake.h b/net/handshake/handshake.h
index 4dac965c99df..8aeaadca844f 100644
--- a/net/handshake/handshake.h
+++ b/net/handshake/handshake.h
@@ -31,6 +31,7 @@ struct handshake_req {
 	struct list_head		hr_list;
 	struct rhash_head		hr_rhash;
 	unsigned long			hr_flags;
+	struct file			*hr_file;
 	const struct handshake_proto	*hr_proto;
 	struct sock			*hr_sk;
 	void				(*hr_odestruct)(struct sock *sk);
diff --git a/net/handshake/request.c b/net/handshake/request.c
index 94d5cef3e048..d78d41abb3d9 100644
--- a/net/handshake/request.c
+++ b/net/handshake/request.c
@@ -239,6 +239,7 @@ int handshake_req_submit(struct socket *sock, struct handshake_req *req,
 	}
 	req->hr_odestruct = req->hr_sk->sk_destruct;
 	req->hr_sk->sk_destruct = handshake_sk_destruct;
+	req->hr_file = sock->file;
 
 	ret = -EOPNOTSUPP;
 	net = sock_net(req->hr_sk);
@@ -334,6 +335,9 @@ bool handshake_req_cancel(struct sock *sk)
 		return false;
 	}
 
+	/* Request accepted and waiting for DONE */
+	fput(req->hr_file);
+
 out_true:
 	trace_handshake_cancel(net, req, sk);