Re: disable-cap-mlock

William Lee Irwin III
2004-04-01T17:51:36Z

On Thu, Apr 01, 2004 at 12:37:51PM -0500, Stephen Smalley wrote:
>> What prevents any uid 0 process from changing these sysctl settings
>> (aside from SELinux, if you happen to use it and configure the policy
>> accordingly)?

On Thu, Apr 01, 2004 at 09:44:05AM -0800, William Lee Irwin III wrote:
> I'm aware it does some very unintelligent things to the security model,
> e.g. anyone with fs-level access to these things can basically escalate
> their capabilities to "everything". Maybe some kind of big fat warning
> is in order.

Index: mm4-2.6.5-rc3/security/Kconfig
===================================================================
--- mm4-2.6.5-rc3.orig/security/Kconfig 2004-04-01 07:38:49.000000000 -0800
+++ mm4-2.6.5-rc3/security/Kconfig 2004-04-01 09:49:43.000000000 -0800
@@ -49,6 +49,13 @@
depends on SECURITY!=n
help
This allows you to disable capabilities with sysctls.
+ It effectively breaks the kernel's security model so that
+ any user with fs-level access to /proc/sys/capability/*
+ can escalate their privileges to "able to do anything",
+ but some users have special-case needs for these things.
+ Don't use this on any system with untrusted local users.
+ It's probably best to firewall the living daylights out
+ of anything using this also.

source security/selinux/Kconfig