Messages in this thread | | | Date | Wed, 28 Aug 2013 17:30:25 -0700 | Subject | Re: [PATCH 1/2] procfs: restore 0400 permissions on /proc/*/{syscall,stack,personality} | From | Kees Cook <> |
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On Wed, Aug 28, 2013 at 5:26 PM, Eric W. Biederman <ebiederm@xmission.com> wrote: > Can someome please state what they are worried about in simple language > step by step? > [...] > The closest I saw in the thread was people were worried about ASLR being > defeated. All I see are kernel addresses and we don't have much if any > runtime or even load time randomization of where code is located in the > kernel address map on x86_64. So I don't understand the concern.
I showed the output of "syscall", since that contains user-space addresses and shows a leak of ASLR from a privileged process to an unprivileged process.
The flaw as I see it is that an unprivileged process opens /proc/$priv_pid/syscall and passes it to a setuid process which is able to read it, and provides those contents to the unprivileged process.
The unprivileged process should not be able to the open the file in the first place.
-Kees
-- Kees Cook Chrome OS Security
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