Date:   Mon, 27 Feb 2023 11:07:50 -0800
From:   Jakub Kicinski <kuba@kernel.org>
To:     Hangyu Hua <hbh25y@gmail.com>
Cc:     Sabrina Dubroca <sd@queasysnail.net>,
        Florian Westphal <fw@strlen.de>, borisp@nvidia.com,
        john.fastabend@gmail.com, davem@davemloft.net, edumazet@google.com,
        pabeni@redhat.com, davejwatson@fb.com, aviadye@mellanox.com,
        ilyal@mellanox.com, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] net: tls: fix possible race condition between
 do_tls_getsockopt_conf() and do_tls_setsockopt_conf()
Message-ID: <20230227110750.6988fca5@kernel.org>
In-Reply-To: <52faaa10-f3e4-bca9-4bff-6f1ea7d26593@gmail.com>
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        <20230224120606.GI26596@breakpoint.cc>
        <20230224105508.4892901f@kernel.org>
        <Y/kck0/+NB+Akpoy@hog>
        <20230224130625.6b5261b4@kernel.org>
        <Y/kwyS2n4uLn8eD0@hog>
        <20230224141740.63d5e503@kernel.org>
        <52faaa10-f3e4-bca9-4bff-6f1ea7d26593@gmail.com>
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On Mon, 27 Feb 2023 11:26:18 +0800 Hangyu Hua wrote:
> In order to reduce ambiguity, I think it may be a good idea only to
> lock do_tls_getsockopt_conf() like we did in do_tls_setsockopt()
> 
> It will look like:
> 
> static int do_tls_getsockopt(struct sock *sk, int optname,
> 			     char __user *optval, int __user *optlen)
> {
> 	int rc = 0;
> 
> 	switch (optname) {
> 	case TLS_TX:
> 	case TLS_RX:
> +		lock_sock(sk);
> 		rc = do_tls_getsockopt_conf(sk, optval, optlen,
> 					    optname == TLS_TX);
> +		release_sock(sk);
> 		break;
> 	case TLS_TX_ZEROCOPY_RO:
> 		rc = do_tls_getsockopt_tx_zc(sk, optval, optlen);
> 		break;
> 	case TLS_RX_EXPECT_NO_PAD:
> 		rc = do_tls_getsockopt_no_pad(sk, optval, optlen);
> 		break;
> 	default:
> 		rc = -ENOPROTOOPT;
> 		break;
> 	}
> 	return rc;
> }
> 
> Of cause, I will clean the lock in do_tls_getsockopt_conf(). What do you
> guys think?

I'd suggest to take the lock around the entire switch statement.