Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Message-ID: <019e96b5-4047-6458-0cfa-c9ef8f0d0470@gmail.com>
Date:   Tue, 2 Nov 2021 20:39:51 -0600
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0)
 Gecko/20100101 Thunderbird/91.2.1
Subject: Re: [PATCH v2 09/25] tcp: authopt: Disable via sysctl by default
Content-Language: en-US
To:     Leonard Crestez <cdleonard@gmail.com>,
        David Ahern <dsahern@kernel.org>,
        Shuah Khan <shuah@kernel.org>,
        Dmitry Safonov <0x7f454c46@gmail.com>,
        Eric Dumazet <edumazet@google.com>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Kuniyuki Iwashima <kuniyu@amazon.co.jp>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Jakub Kicinski <kuba@kernel.org>,
        Yuchung Cheng <ycheng@google.com>,
        Francesco Ruggeri <fruggeri@arista.com>,
        Mat Martineau <mathew.j.martineau@linux.intel.com>,
        Christoph Paasch <cpaasch@apple.com>,
        Ivan Delalande <colona@arista.com>,
        Priyaranjan Jha <priyarjha@google.com>, netdev@vger.kernel.org,
        linux-crypto@vger.kernel.org, linux-kselftest@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <cover.1635784253.git.cdleonard@gmail.com>
 <137399b962131c278acbfa5446a3b6d59aa0547b.1635784253.git.cdleonard@gmail.com>
From:   David Ahern <dsahern@gmail.com>
In-Reply-To: <137399b962131c278acbfa5446a3b6d59aa0547b.1635784253.git.cdleonard@gmail.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 11/1/21 10:34 AM, Leonard Crestez wrote:
> diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
> index 97eb54774924..cc34de6e4817 100644
> --- a/net/ipv4/sysctl_net_ipv4.c
> +++ b/net/ipv4/sysctl_net_ipv4.c
> @@ -17,10 +17,11 @@
>  #include <net/udp.h>
>  #include <net/cipso_ipv4.h>
>  #include <net/ping.h>
>  #include <net/protocol.h>
>  #include <net/netevent.h>
> +#include <net/tcp_authopt.h>
>  
>  static int two = 2;
>  static int three __maybe_unused = 3;
>  static int four = 4;
>  static int thousand = 1000;
> @@ -583,10 +584,19 @@ static struct ctl_table ipv4_table[] = {
>  		.mode		= 0644,
>  		.proc_handler	= proc_douintvec_minmax,
>  		.extra1		= &sysctl_fib_sync_mem_min,
>  		.extra2		= &sysctl_fib_sync_mem_max,
>  	},
> +#ifdef CONFIG_TCP_AUTHOPT
> +	{
> +		.procname	= "tcp_authopt",
> +		.data		= &sysctl_tcp_authopt,
> +		.maxlen		= sizeof(int),
> +		.mode		= 0644,
> +		.proc_handler	= proc_dointvec,

Just add it to the namespace set, and this could be a u8 (try to plug a
hole if possible) with min/max specified:

                .maxlen         = sizeof(u8),
                .mode           = 0644,
                .extra1         = SYSCTL_ZERO,
                .extra2         = SYSCTL_ONE


see icmp_echo_enable_probe as an example. And if you are not going to
clean up when toggled off, you need a handler that tells the user it can
not be disabled by erroring out on attempts to disable it.