linux-kernel - RE: [PATCH] vsock: ratelimit unknown ioctl error message

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <3e34e4121f794355891fd7577c9dfbc0@AcuMS.aculab.com>
Date:   Mon, 26 Oct 2020 09:46:17 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Stefano Garzarella' <sgarzare@...hat.com>
CC:     Colin King <colin.king@...onical.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] vsock: ratelimit unknown ioctl error message

From: Stefano Garzarella
> Sent: 26 October 2020 09:39
> 
> On Mon, Oct 26, 2020 at 09:13:23AM +0000, David Laight wrote:
> >From: Stefano Garzarella
> >> Sent: 26 October 2020 08:43
> >...
> >> >Isn't the canonical error for unknown ioctl codes -ENOTTY?
> >> >
> >>
> >> Oh, thanks for pointing that out!
> >>
> >> I had not paid attention to the error returned, but looking at it I
> >> noticed that perhaps the most appropriate would be -ENOIOCTLCMD.
> >> In the ioctl syscall we return -ENOTTY, if the callback returns
> >> -ENOIOCTLCMD.
> >>
> >> What do you think?
> >
> >It is 729 v 443 in favour of ENOTTY (based on grep).
> 
> Under net/ it is 6 vs 83 in favour of ENOIOCTLCMD.
> 
> >
> >No idea where ENOIOCTLCMD comes from, but ENOTTY probably
> >goes back to the early 1970s.
> 
> Me too.
> 
> >
> >The fact that the ioctl wrapper converts the value is a good
> >hint that userspace expects ENOTTY.
> 
> Agree on that, but since we are not interfacing directly with userspace,
> I think it is better to return the more specific error (ENOIOCTLCMD).

I bet Linux thought it could use a different error code then
found that 'unknown ioctl' was spelt ENOTTY.

Back in the old days error values were probably almost unique.
strerror(EAGIAN) was "No more processes" for a long time!

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)