From: David Ahern <dsahern@gmail.com>
To: Ishaan Gandhi <ishaangandhi@gmail.com>
Cc: David Miller <davem@davemloft.net>,
Network Development <netdev@vger.kernel.org>,
willemb@google.com,
Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: [PATCH v3] icmp: support rfc5837
Date: Fri, 19 Mar 2021 17:54:54 -0600 [thread overview]
Message-ID: <45eff141-30fb-e8af-5ca5-034a86398ac9@gmail.com> (raw)
In-Reply-To: <5E97397E-7028-46E8-BC0D-44A3E30C41A4@gmail.com>
On 3/19/21 10:11 AM, Ishaan Gandhi wrote:
> Thank you. Would it be better to do instead:
>
> + if_index = skb->skb_iif;
>
> or
>
> + if_index = ip_version == 4 ? inet_iif(skb) : skb->skb_iif;
>
If the packet comes in via an interface assigned to a VRF, skb_iif is
most likely the VRF index which is not what you want.
The general problem of relying on skb_iif was discussed on v1 and v2 of
your patch. Returning an iif that is a VRF, as an example, leaks
information about the networking configuration of the device which from
a quick reading of the RFC is not the intention.
Further, the Security Considerations section recommends controls on what
information can be returned where you have added a single sysctl that
determines if all information or none is returned. Further, it is not a
a per-device control but a global one that applies to all net devices -
though multiple entries per netdevice has a noticeable cost in memory at
scale.
In the end it seems to me the cost benefit is not there for a feature
like this.
next prev parent reply other threads:[~2021-03-19 23:56 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-17 22:19 [PATCH v3] icmp: support rfc5837 ishaangandhi
2021-03-19 14:55 ` David Ahern
2021-03-19 16:11 ` Ishaan Gandhi
2021-03-19 23:54 ` David Ahern [this message]
2021-03-20 0:53 ` Willem de Bruijn
2021-03-20 4:24 ` David Ahern
2021-03-20 20:35 ` rfc5837 and rfc8335 David Ahern
2021-03-22 1:50 ` Ishaan Gandhi
[not found] ` <CAJByZJBNMqVDXjcOGCJHGcAv+sT4oEv1FD608TpA_e-J2a3L2w@mail.gmail.com>
[not found] ` <BL0PR05MB5316A2F5C2F1A727FA0190F3AE649@BL0PR05MB5316.namprd05.prod.outlook.com>
2021-03-25 3:19 ` David Ahern
2021-03-29 14:49 ` Ron Bonica
2021-03-29 19:39 ` Ron Bonica
2021-03-31 14:04 ` Willem de Bruijn
2021-03-31 17:56 ` Ron Bonica
2021-04-08 22:03 ` Ishaan Gandhi
2021-05-03 1:41 ` RESEND " Ishaan Gandhi
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