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  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]
Date:	Tue, 14 Oct 2014 15:13:16 -0700
From:	Andy Lutomirski <>
To:	"Eric W. Biederman" <>
Cc:	Linux FS Devel <>,
	"" <>,
	Michael j Theall <>,,
	Miklos Szeredi <>,
	"Serge H. Hallyn" <>,
	Seth Forshee <>
Subject: Re: [PATCH] fs: Treat non-ancestor-namespace mounts as MNT_NOSUID

On Tue, Oct 14, 2014 at 3:07 PM, Andy Lutomirski <> wrote:
> On Tue, Oct 14, 2014 at 2:57 PM, Eric W. Biederman

>>> Seth, this should address a problem that's related to yours.  If a
>>> userns creates and untrusted fs (by any means, although admittedly fuse
>>> and user namespaces don't work all that well together right now), then
>>> this prevents shenanigans that could happen when the userns passes an fd
>>> pointing at the filesystem out to the root ns.
>> Andy for now I really think we are best not even reading those
>> capabilities into the vfs from unprivileged mounts.
> But won't we want to support letting userns containers create setuid
> files and security labels using FUSE and related things for their own
> benefit someday?  This lets us do that without compromising the init
> namespace.

More concretely, root in a userns should be able to have a
setuid-whomever or security-labeled file, and another user in that
userns should be able to exec it and transition.  But, if you're
outside the userns, then:

$ /proc/PID_IN_USERNS/root/path/to/labeled/file

shouldn't transition.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists