linux-kernel - Re: [PATCH bpf-next 2/2] selftests/bpf: Extend test fs

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: <B6CD210E-96C6-4730-BD05-EC3A0C6905EB@fb.com>
Date: Thu, 31 Oct 2024 15:56:54 +0000
From: Song Liu <songliubraving@...a.com>
To: Christoph Hellwig <hch@...radead.org>
CC: Song Liu <songliubraving@...a.com>,
        Christian Brauner
	<brauner@...nel.org>, Jan Kara <jack@...e.cz>,
        Song Liu <song@...nel.org>, bpf <bpf@...r.kernel.org>,
        Linux-Fsdevel <linux-fsdevel@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Kernel Team <kernel-team@...a.com>,
        Andrii Nakryiko <andrii@...nel.org>,
        Eduard Zingerman <eddyz87@...il.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Al Viro <viro@...iv.linux.org.uk>, KP Singh <kpsingh@...nel.org>,
        Matt Bobrowski <mattbobrowski@...gle.com>
Subject: Re: [PATCH bpf-next 2/2] selftests/bpf: Extend test fs_kfuncs to
 cover security.bpf xattr names



> On Oct 30, 2024, at 11:56 PM, Christoph Hellwig <hch@...radead.org> wrote:
> 
> On Wed, Oct 30, 2024 at 08:44:26PM +0000, Song Liu wrote:
>> Given bpf kfuncs can read user.* xattrs for almost a year now, I think we 
>> cannot simply revert it. We already have some users using it. 
>> 
>> Instead, we can work on a plan to deprecated it. How about we add a 
>> WARN_ON_ONCE as part of this patchset, and then remove user.* support 
>> after some time?
> 
> As Christian mentioned having bpf access to user xattrs is probably
> not a big issue.  OTOH anything that makes security decisions based
> on it is probably pretty broken.  Not sure how you want to best
> handle that.

Agreed that we really need security.bpf prefix for security use cases. 
Reading user.* xattrs could be useful for some tracing use cases. We
may also introduce other prefixes for future use cases.

Thanks,
Song