[lkml]   [2010]   [Nov]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] kernel: make /proc/kallsyms mode 400 to reduce ease of attacking
On 11/29/2010 10:04 AM, Ingo Molnar wrote:
> * Sarah Sharp <> wrote:
>> On Fri, Nov 26, 2010 at 08:48:09AM +0100, Ingo Molnar wrote:
>>> * Linus Torvalds <> wrote:
>>>> On Fri, Nov 19, 2010 at 11:19 AM, Sarah Sharp
>>>> <> wrote:
>>>>> .config and dmesg are attached. The box is running klogd 1.5.5ubuntu3
>>>>> (from Jaunty). Yes, I know that's old. I read the bit in the commit
>>>>> about changing the permissions of kallsyms after boot, but if I can't
>>>>> boot that doesn't help. Perhaps this can be made a configuration
>>>>> option?
>>>> It's not worth a config option.
>>>> If it actually breaks user-space, I think we should just revert it.
>>> Sarah,
>>> Does your system boot fine if we make /proc/kallsyms simply an empty file to
>>> unprivileged users? Something like the (untested ...) patch below.
>> Yes, that works. The system boots as normal. `cat /proc/kallsyms`
>> returns an empty file, and `sudo cat /proc/kallsyms` does not.
> Great! Marcus, mind respinning your patch with that approach?

Can we please not use CAP_SYS_ADMIN for this? Relying on CAP_SYS_ADMIN
is worse than anything else -- it is a fixed policy hardcoded in the
kernel, with no ability for the system owner to delegate the policy
outward, e.g. by adding group read permission and/or chgrp the file.

Delegating CAP_SYS_ADMIN, of course, otherwise known as "everything", is
worse than anything...


 \ /
  Last update: 2010-11-29 20:11    [W:0.064 / U:19.580 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site