Openwall GNU/*/Linux - a small security-enhanced Linux distro for servers
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Tue, 01 Oct 2013 18:40:41 -0700
From: Andy Lutomirski <>
To: Djalal Harouni <>
CC: "Eric W. Biederman" <>, 
 Kees Cook <>,
 Al Viro <>, 
 Andrew Morton <>,
 Linus Torvalds <>, 
 Ingo Molnar <>,
 "Serge E. Hallyn" <>, 
 Cyrill Gorcunov <>,
 David Rientjes <>, 
 LKML <>,,,
Subject: Re: [PATCH v2 0/9] procfs: protect /proc/<pid>/* files with file->f_cred

On 10/01/2013 01:26 PM, Djalal Harouni wrote:
> /proc/<pid>/* entries varies at runtime, appropriate permission checks
> need to happen during each system call.
> Currently some of these sensitive entries are protected by performing
> the ptrace_may_access() check. However even with that the /proc file
> descriptors can be passed to a more privileged process
> (e.g. a suid-exec) which will pass the classic ptrace_may_access()
> check. In general the ->open() call will be issued by an unprivileged
> process while the ->read(),->write() calls by a more privileged one.
> Example of these files are:
> /proc/*/syscall, /proc/*/stack etc.
> And any open(/proc/self/*) then suid-exec to read()/write() /proc/self/*
> These files are protected during read() by the ptrace_may_access(),
> however the file descriptor can be passed to a suid-exec which can be
> used to read data and bypass ASLR. Of course this was discussed several
> times on LKML.

Can you elaborate on what it is that you're fixing?  That is, can you
give a concrete example of what process opens what file and passes the
fd to what process?

I'm having trouble following your description.


Powered by blists - more mailing lists

Your e-mail address:

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.