Messages in this thread | | | Date | Wed, 2 Apr 2014 12:20:49 -0500 | From | Serge Hallyn <> | Subject | Re: [lxc-devel] Kernel bug? Setuid apps and user namespaces |
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Hi Eric,
(sorry, I don't seem to have the email I actually wanted to reply to in my mbox, but it is https://lists.linuxcontainers.org/pipermail/lxc-devel/2013-October/005857.html)
You'd said, > Someone needs to read and think through all of the corner cases and see > if we can ever have a time when task_dumpable is false but root in the > container would not or should not be able to see everything. > > In particular I am worried about the case of a setuid app calling setns, > and entering a lesser privileged user namespace. In my foggy mind that > might be a security problem. And there might be other similar crazy > cases.
Can we make use of current->mm->exe_file->f_cred->user_ns?
So either always use make_kgid(current->mm->exe_file->f_cred->user_ns, 0) instead of make_kuid(cred->user_ns, 0), or check that (current->mm->exe_file->f_cred->user_ns == cred->user_ns) and, if not, assume that the caller has done a setns?
-serge
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