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Date: Sat, 25 Jun 2011 21:35:01 +0400
From: Vasiliy Kulikov <>
Subject: procfs io and taskstats infoleaks, proc/pid/* threats

(Bringing the subject to the list)

While implementing HARDEN_PROC and arguing with LKML folks about
usefullness of the feature, I've discovered /proc/pid/io and taskstats
interfaces can be used to gather rather sensitive information, like
password length:

The suggested patches:

taskstats patch is partial, it doesn't honor set{u,g}ids and processes
using caps.  For the full fix ptrace_task_may_access_current() is
needed, the patch adding it is pending:

I'd appreciate if somebody points me how information stored in
sched, schedstats, stat, and status files can be exploited.  I suspect
it can be used similar way.

Other thoughts:

Files mountinfo, mounts store information related to the process' fs
namespace.  I feel this information can be somewhat private, e.g. mount
points can reveal private file pathes in case of separate namespaces
where this information cannot be learned by reading /proc/self/mountinfo. 

Files limits and status store process related restrictions.  I dunno
whether this can be considered as a private information.

I'd appeciate any comment.


Vasiliy Kulikov - bringing security into open computing environments

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