From: Leonard Crestez <cdleonard@gmail.com>
To: David Ahern <dsahern@gmail.com>,
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,
Shuah Khan <shuah@kernel.org>,
linux-hardening@vger.kernel.org,
Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH v2 09/25] tcp: authopt: Disable via sysctl by default
Date: Fri, 5 Nov 2021 10:50:01 +0200 [thread overview]
Message-ID: <de6030e6-7280-4835-3864-3595e267fcdd@gmail.com> (raw)
In-Reply-To: <019e96b5-4047-6458-0cfa-c9ef8f0d0470@gmail.com>
On 11/3/21 4:39 AM, David Ahern wrote:
> 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.
This is deliberately per-system because the goal is to avoid possible
local privilege escalations by reducing the attack surface. Even the
smallest flaw could be exploited by a malicious application establishing
an authenticated connection on loopback.
Applications running in containers frequently have full access to
sysctls so making this per-namespace would defeat the original purpose.
I can't think of any reason to prevent using this feature at the
namespace level, it has no interesting effects outside TCP connections
for which it is enabled.
I also believe that as similar sysctl would be useful for TCP-MD5.
You're right about adding additional prints.
--
Regards,
Leonard
next prev parent reply other threads:[~2021-11-05 8:50 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-01 16:34 [PATCH v2] tcp: Initial support for RFC5925 auth option Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 01/25] tcp: authopt: Initial support and key management Leonard Crestez
2021-11-03 2:29 ` David Ahern
2021-11-05 12:10 ` Leonard Crestez
2021-11-05 1:22 ` Dmitry Safonov
2021-11-05 7:04 ` Leonard Crestez
2021-11-05 14:50 ` Dmitry Safonov
2021-11-05 18:00 ` Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 02/25] docs: Add user documentation for tcp_authopt Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 03/25] selftests: Initial tcp_authopt test module Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 04/25] selftests: tcp_authopt: Initial sockopt manipulation Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 05/25] tcp: authopt: Add crypto initialization Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 06/25] tcp: authopt: Compute packet signatures Leonard Crestez
2021-11-05 1:53 ` Dmitry Safonov
2021-11-05 6:39 ` Leonard Crestez
2021-11-05 2:08 ` Dmitry Safonov
2021-11-05 6:09 ` Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 07/25] tcp: Use BIT() for OPTION_* constants Leonard Crestez
2021-11-03 2:31 ` David Ahern
2021-11-03 22:19 ` Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 08/25] tcp: authopt: Hook into tcp core Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 09/25] tcp: authopt: Disable via sysctl by default Leonard Crestez
2021-11-03 2:39 ` David Ahern
2021-11-05 8:50 ` Leonard Crestez [this message]
2021-11-05 1:46 ` Dmitry Safonov
2021-11-01 16:34 ` [PATCH v2 10/25] selftests: tcp_authopt: Test key address binding Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 11/25] tcp: authopt: Implement Sequence Number Extension Leonard Crestez
2021-11-01 19:22 ` Francesco Ruggeri
2021-11-02 10:03 ` Leonard Crestez
2021-11-02 19:21 ` Francesco Ruggeri
2021-11-03 22:01 ` Leonard Crestez
2021-11-01 20:54 ` Eric Dumazet
2021-11-02 9:50 ` Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 12/25] tcp: ipv6: Add AO signing for tcp_v6_send_response Leonard Crestez
2021-11-03 2:44 ` David Ahern
2021-11-03 22:09 ` Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 13/25] tcp: authopt: Add support for signing skb-less replies Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 14/25] tcp: ipv4: Add AO signing for " Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 15/25] selftests: tcp_authopt: Implement SNE in python Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 16/25] selftests: tcp_authopt: Add scapy-based packet signing code Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 17/25] selftests: tcp_authopt: Add packet-level tests Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 18/25] selftests: tcp_authopt: Initial sne test Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 19/25] tcp: authopt: Add key selection controls Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 20/25] selftests: tcp_authopt: Add tests for rollover Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 21/25] tcp: authopt: Add initial l3index support Leonard Crestez
2021-11-03 3:06 ` David Ahern
2021-11-05 12:26 ` Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 22/25] selftests: tcp_authopt: Initial tests for l3mdev handling Leonard Crestez
2021-11-01 16:34 ` [PATCH v2 23/25] selftests: nettest: Rename md5_prefix to key_addr_prefix Leonard Crestez
2021-11-03 3:08 ` David Ahern
2021-11-01 16:34 ` [PATCH v2 24/25] selftests: nettest: Initial tcp_authopt support Leonard Crestez
2021-11-03 3:09 ` David Ahern
2021-11-01 16:35 ` [PATCH v2 25/25] selftests: net/fcnal: " Leonard Crestez
2021-11-03 3:18 ` [PATCH v2] tcp: Initial support for RFC5925 auth option David Ahern
2021-11-03 22:22 ` Leonard Crestez
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