Re: [PATCH] USB: disable all RNDIS protocol drivers

On Wed, 2023-07-12 at 18:39 +0200, Greg Kroah-Hartman wrote:

On Wed, Jul 12, 2023 at 03:00:55PM +0200, Johannes Berg wrote:

quoted

On Wed, 2023-07-12 at 11:22 +0200, Oliver Neukum wrote:

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On 04.07.23 08:47, Greg Kroah-Hartman wrote:

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On Mon, Jul 03, 2023 at 11:11:57PM +0200, Enrico Mioso wrote:

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Hi all!!

I think the rndis_host USB driver might emit a warning in the dmesg, but disabling the driver wouldn't be a good idea.
The TP-Link MR6400 V1 LTE modem and also some ZTE modems integrated in routers do use this protocol.

We may also distinguish between these cases and devices you might plug in - as they pose different risk levels.

Again, you have to fully trust the other side of an RNDIS connection,
any hints on how to have the kernel determine that?

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it is a network protocol. So this statement is kind of odd.
Are you saying that there are RNDIS messages that cannot be verified
for some reason, that still cannot be disclosed?

Agree, it's also just a USB device, so no special trickery with DMA,
shared buffers, etc.

I mean, yeah, the RNDIS code is really old and almost certainly has a
severe lack of input validation, but that still doesn't mean it's
fundamentally impossible.

You all are going to make me have to write some exploits aren't you...

This is getting a bit childish. Nobody ever said that wasn't possible,
in fact I did say exactly above that I'm sure since it's old and all it
lacks input validation. So yeah, I full well believe that you can write
exploits for it.

All we said is that your statement of "RNDIS is fundamentally unfixable"
doesn't make a lot of sense. If this were the case, all USB drivers
would have to "trust the other side" as well, right?

johannes