Messages in this thread | | | Date | Tue, 6 Jul 2004 12:31:41 -0400 | From | Alan Cox <> | Subject | Re: question about /proc/<PID>/mem in 2.4 |
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On Tue, Jul 06, 2004 at 02:08:04PM +0100, Tigran Aivazian wrote: > > This code was added to stop the ptrace/kmod vulnerabilities. I do not > > fully understand the issues around tsk->is_dumpable and the fix itself, > > but I agree on that the checks here could be relaxed for the super user.
is_dumpable tells you various things in 2.4, including whether the curent memory image is valid, and as a race preventor for ptrace during exec of setuid apps. You should probably talk to Solar Designer about the whole design of the dump/suid race fixing work rather than me.
We also had to deal with another nasty case which could be fixed by grabbing the mm at open time (which then opens a resource attack bug).
Consider what happens if your setuid app reads stdin
setuidapp < /proc/self/mem
(No idea how 2.6 deals with these but if its got better backportable ways that *actually work* it might make sense).
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