Thread (17 messages) 17 messages, 6 authors, 2025-11-24

Re: [PATCH] nbd: restrict sockets to TCP and UDP

From: Simon Horman <horms@kernel.org>
Date: 2025-09-12 09:23:27
Also in: linux-block, lkml

On Tue, Sep 09, 2025 at 08:33:27AM -0700, Eric Dumazet wrote:
On Tue, Sep 9, 2025 at 8:19 AM Richard W.M. Jones [off-list ref] wrote:
quoted
On Tue, Sep 09, 2025 at 07:47:09AM -0700, Eric Dumazet wrote:
quoted
On Tue, Sep 9, 2025 at 7:37 AM Jens Axboe [off-list ref] wrote:
quoted
On 9/9/25 8:35 AM, Eric Dumazet wrote:
quoted
On Tue, Sep 9, 2025 at 7:04 AM Eric Dumazet [off-list ref] wrote:
quoted
On Tue, Sep 9, 2025 at 6:32 AM Richard W.M. Jones [off-list ref] wrote:
quoted
On Tue, Sep 09, 2025 at 01:22:43PM +0000, Eric Dumazet wrote:
...
quoted
From the outside it seems really odd to hard code a list of "good"
socket types into each kernel client that can open a socket.  Normally
if you wanted to restrict socket types wouldn't you do that through
something more flexible like nftables?
nftables is user policy.

We need a kernel that will not crash, even if nftables is not
compiled/loaded/used .
Hi Rich, Eric, all,

FWIIW, I think that the kernel maintaining a list of acceptable and
known to work socket types is a reasonable measure. It reduces the
surface where problems can arise - a surface that has real bugs.
And can be expanded as necessary.

For sure it is not perfect. There is a risk of entering wack-a-mole
territory. And a more flexible mechanism may be nice.

But, OTOH, we may be speculating about a problem that doesn't exist.
If, very occasionally, a new socket type comes along and has to be used.
Or perhaps more likely, there is a follow-up to this change for some
cases it missed (i.e. the topic of this thread). And if that is very
occasional. Is there really a problem?

The answer is of course subjective. But I lean towards no.

...
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