Messages in this thread | | | Date | Tue, 6 Jul 2004 14:08:04 +0100 (BST) | From | Tigran Aivazian <> | Subject | Re: question about /proc/<PID>/mem in 2.4 |
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On Tue, 6 Jul 2004, Marcelo Tosatti wrote: > On Tue, Jul 06, 2004 at 12:14:04PM +0100, Tigran Aivazian wrote: > > Ok, but still nobody seems to know why the super user is not allowed to > > access /proc/<PID>/mem of any task. Any code which nobody in the world > > knows the reason for, is broken and should be removed. > > > > I will wait a few weeks to see if someone does come up with the reason for > > that "extra secure" check in mem_read() and if nobody has objections I'll > > send Linus a patch to relax the check to a more reasonable one, namely to > > allow CAP_SYS_PTRACE process to bypass any other conditions imposed. > > Hi Tigran, > > 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. > > However changing it to > > if (!is_dumpable(task) && !capable(CAP_SYS_PTRACE)) > goto out; > > Seems wrong because this will stop always honoring the tsk->is_dumpable flag. (?) > > Alan for sure can make the picture clear - he wrote this thing.
Ok, let's see what Alan says then (if he has time to look at it).
Btw, the mem_read() code in both 2.4 and 2.6 can be cleaned up to use get_task_mm() inline instead of doing it inline "manually".
Kind regards Tigran
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