3.0: user namespace problem with capabilities

From: Arkadiusz Miskiewicz
Date: Thu Jul 21 2011 - 08:22:35 EST


linux-vserver guys think that there is a problem with user namespace in
upcoming 3.0

"this is a mainline/upstream bug, which basically happens
when unsharing the USER namespace. what happens is that
all capabilities are dropped, and as result, the userspace
tool cannot issue Linux-VServer syscall commands anymore
(because of missing CAP_CONTEXT)"

"this can be verified on vanilla linux-3.0 kernels with
in the following way:

gcc -o clone_newuser clone_newuser.c
./clone_newuser ls /root/

assuming that /root does not have any right for 'other'
this will result in a permission denied (when the USER
namespace is compiled into the kernel)"

Whole post:


What's maintainers opinion on this?
Arkadiusz MiÅkiewicz PLD/Linux Team
arekm / maven.pl http://ftp.pld-linux.org/
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