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Date: Tue, 7 May 2024 12:02:10 +0300
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Subject: Re: [PATCH v6 0/3] implement OA2_CRED_INHERIT flag for openat2()
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To: Aleksa Sarai <cyphar@cyphar.com>
Cc: linux-kernel@vger.kernel.org, Stefan Metzmacher <metze@samba.org>,
 Eric Biederman <ebiederm@xmission.com>,
 Alexander Viro <viro@zeniv.linux.org.uk>, Andy Lutomirski <luto@kernel.org>,
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 Jeff Layton <jlayton@kernel.org>, Chuck Lever <chuck.lever@oracle.com>,
 Alexander Aring <alex.aring@gmail.com>,
 David Laight <David.Laight@aculab.com>, linux-fsdevel@vger.kernel.org,
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 =?UTF-8?Q?Christian_G=C3=B6ttsche?= <cgzones@googlemail.com>
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07.05.2024 10:50, Aleksa Sarai пишет:
> If you are a privileged process which plans to change users,

Not privileged at all.
But I think what you say is still possible
with userns?


> A new attack I just thought of while writing this mail is that because
> there is no RESOLVE_NO_XDEV requirement, it should be possible for the
> process to get an arbitrary write primitive by creating a new
> userns+mountns and then bind-mounting / underneath the directory.
Doesn't this need a write perm to a
directory? In his case this is not a threat,
because you are not supposed to have a
write perm to that dir. OA2_CRED_INHERIT
is the only way to write.