Re: [PATCH 5/7] FUSE: implement ioctl support

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To: <tj@...>
Cc: <miklos@...>, <greg@...>, <fuse-devel@...>, <linux-kernel@...>
Date: Friday, August 29, 2008 - 3:59 am

On Fri, 29 Aug 2008, Tejun Heo wrote:

Yes and no.  Fuse allows this protection to be relaxed
(-oallow_other), because it does provide quite good privilege
separation.  This ioctl thing breaks that, so we should disable ioctls
with 'allow_other' or require the filesystem to be privileged.  But
the latter is not easy because mount(2) is always privileged, we don't
know if the process calling fusermount was privileged or not.

So, your current patch actually _introduces_ a security vulnerability
with the 'allow_other' mount option.


What do you call client?  If you mean the app using the char dev, then
I don't see how it could break out of any protection.


Dunno.  Isn't there some transformation of pids going on, so that the
global namespace can access pids in all containers but under a
different alias?  I do hope somethinig like this works, otherwise it's
not only fuse that will break.

Miklos
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Messages in current thread:
Re: [PATCHSET] FUSE: extend FUSE to support more operations, Miklos Szeredi, (Thu Nov 13, 10:48 am)
Re: [PATCHSET] FUSE: extend FUSE to support more operations, Miklos Szeredi, (Thu Nov 13, 11:52 am)
Re: [PATCHSET] FUSE: extend FUSE to support more operations, Christoph Hellwig, (Wed Nov 12, 5:14 am)
Re: [fuse-devel] [PATCHSET] FUSE: extend FUSE to support mor..., Szabolcs Szakacsits, (Tue Oct 14, 8:16 am)
[PATCH 5/7] FUSE: implement ioctl support, Tejun Heo, (Thu Aug 28, 1:41 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, H. Peter Anvin, (Thu Aug 28, 2:20 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Tejun Heo, (Thu Aug 28, 2:28 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, H. Peter Anvin, (Thu Aug 28, 3:08 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Miklos Szeredi, (Thu Aug 28, 3:18 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, H. Peter Anvin, (Thu Aug 28, 4:21 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Miklos Szeredi, (Thu Aug 28, 4:55 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, H. Peter Anvin, (Thu Aug 28, 5:27 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Miklos Szeredi, (Fri Aug 29, 3:32 am)
Re: [PATCH 5/7] FUSE: implement ioctl support, Greg KH, (Thu Aug 28, 1:51 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Tejun Heo, (Thu Aug 28, 1:59 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Tejun Heo, (Thu Aug 28, 2:02 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Greg KH, (Thu Aug 28, 2:14 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Tejun Heo, (Thu Aug 28, 2:25 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Tejun Heo, (Thu Aug 28, 2:01 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Miklos Szeredi, (Thu Aug 28, 2:13 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Tejun Heo, (Thu Aug 28, 2:17 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Miklos Szeredi, (Thu Aug 28, 2:23 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Tejun Heo, (Thu Aug 28, 2:34 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Alan Cox, (Thu Aug 28, 4:48 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Miklos Szeredi, (Thu Aug 28, 3:25 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Tejun Heo, (Thu Aug 28, 3:42 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Miklos Szeredi, (Thu Aug 28, 4:02 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Tejun Heo, (Thu Aug 28, 10:19 pm)
Re: [fuse-devel] [PATCH 5/7] FUSE: implement ioctl support, Roger Willcocks, (Fri Aug 29, 7:31 am)
Re: [PATCH 5/7] FUSE: implement ioctl support, Miklos Szeredi, (Fri Aug 29, 3:59 am)
Re: [PATCH 5/7] FUSE: implement ioctl support, Tejun Heo, (Fri Aug 29, 4:12 am)
Re: [PATCH 5/7] FUSE: implement ioctl support, Miklos Szeredi, (Fri Aug 29, 4:29 am)
Re: [PATCH 5/7] FUSE: implement ioctl support, Tejun Heo, (Fri Aug 29, 5:03 am)
Re: [PATCH 5/7] FUSE: implement ioctl support, Eric W. Biederman, (Fri Aug 29, 3:17 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Miklos Szeredi, (Mon Sep 1, 7:57 am)
Re: [PATCH 5/7] FUSE: implement ioctl support, Tejun Heo, (Mon Sep 1, 8:03 am)
Re: [PATCH 5/7] FUSE: implement ioctl support, Eric W. Biederman, (Wed Sep 3, 10:32 am)
Re: [PATCH 5/7] FUSE: implement ioctl support, Tejun Heo, (Wed Sep 3, 10:40 am)
Re: [PATCH 5/7] FUSE: implement ioctl support, Eric W. Biederman, (Wed Sep 3, 5:51 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Tejun Heo, (Wed Sep 3, 8:09 pm)
Re: [PATCH 5/7] FUSE: implement ioctl support, Tejun Heo, (Sat Aug 30, 7:40 am)
Re: [PATCH 5/7] FUSE: implement ioctl support, Arnd Bergmann, (Fri Aug 29, 3:47 pm)
[PATCH 7/7] FUSE: implement poll support, Tejun Heo, (Thu Aug 28, 1:41 pm)
[PATCH 4/7] FUSE: implement direct lseek support, Tejun Heo, (Thu Aug 28, 1:41 pm)
[PATCH 1/7] FUSE: add include protectors, Tejun Heo, (Thu Aug 28, 1:40 pm)
[PATCH 3/7] FUSE: implement nonseekable open, Tejun Heo, (Thu Aug 28, 1:40 pm)
[PATCH 2/7] FUSE: pass nonblock flag to client, Tejun Heo, (Thu Aug 28, 1:40 pm)