From: Leonard Crestez <cdleonard@gmail.com>
To: David Ahern <dsahern@gmail.com>,
Eric Dumazet <edumazet@google.com>,
David Ahern <dsahern@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>,
Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
Jakub Kicinski <kuba@kernel.org>, Martin KaFai Lau <kafai@fb.com>,
Kuniyuki Iwashima <kuniyu@amazon.co.jp>,
Yonghong Song <yhs@fb.com>,
Alexander Duyck <alexanderduyck@fb.com>,
Florian Westphal <fw@strlen.de>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] tcp: md5: Fix overlap between vrf and non-vrf keys
Date: Fri, 8 Oct 2021 18:51:56 +0300 [thread overview]
Message-ID: <3b52d69d-c39f-c662-7211-4b9130c8b527@gmail.com> (raw)
In-Reply-To: <5c77ac1a-b6af-982f-d72f-e71098df3112@gmail.com>
On 07.10.2021 21:27, David Ahern wrote:
> On 10/7/21 12:41 AM, Leonard Crestez wrote:
>> On 07.10.2021 04:14, David Ahern wrote:
>>> On 10/6/21 11:48 AM, Leonard Crestez wrote:
>>>> @@ -1103,11 +1116,11 @@ static struct tcp_md5sig_key
>>>> *tcp_md5_do_lookup_exact(const struct sock *sk,
>>>> #endif
>>>> hlist_for_each_entry_rcu(key, &md5sig->head, node,
>>>> lockdep_sock_is_held(sk)) {
>>>> if (key->family != family)
>>>> continue;
>>>> - if (key->l3index && key->l3index != l3index)
>>>> + if (key->l3index != l3index)
>>>
>>> That seems like the bug fix there. The L3 reference needs to match for
>>> new key and existing key. I think the same change is needed in
>>> __tcp_md5_do_lookup.
>>
>> Current behavior is that keys added without tcpm_ifindex will match
>> connections both inside and outside VRFs. Changing this might break real
>> applications, is it really OK to claim that this behavior was a bug all
>> along?
>
> no.
>
> It's been a few years. I need to refresh on the logic and that is not
> going to happen before this weekend.
It seems that always doing a strict key->l3index != l3index condition
inside of __tcp_md5_do_lookup breaks the usecase of binding one listener
to each VRF and not specifying the ifindex for each key.
This is a very valid usecase, maybe the most common way to use md5 with vrf.
Ways to fix this:
* Make this comparison only take effect if TCP_MD5SIG_FLAG_IFINDEX is set.
* Make this comparison only take effect if tcp_l3mdev_accept=1
* Add a new flag?
Right now passing TCP_MD5SIG_FLAG_IFINDEX and ifindex == 0 results in an
error but maybe it should be accepted to mean "key applies only for
default VRF".
--
Regards,
Leonard
next prev parent reply other threads:[~2021-10-08 15:52 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-06 17:48 [PATCH] tcp: md5: Fix overlap between vrf and non-vrf keys Leonard Crestez
2021-10-07 1:14 ` David Ahern
2021-10-07 6:41 ` Leonard Crestez
2021-10-07 18:27 ` David Ahern
2021-10-08 15:51 ` Leonard Crestez [this message]
2021-10-09 17:19 ` David Ahern
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