Re: [PATCH 2/2] file capabilities: removeCONFIG_SECURITY_FILE_CAPABILITIES

From: Chris Wright
Date: Wed Sep 24 2008 - 19:50:33 EST


* Serge E. Hallyn (serue@xxxxxxxxxx) wrote:
> Remove the option to compile the kernel without file capabilities. Not
> compiling file capabilities actually makes the kernel less safe, as it
> includes the possibility for a task changing another task's capabilities.
>
> Some are concerned that userspace tools (and user education) are not
> up to the task of properly configuring file capabilities on a system.
> For those cases, there is now the ability to boot with the no_file_caps
> boot option. This will prevent file capabilities from being used in
> the capabilities recalculation at exec, but will not change the rest
> of the kernel behavior which used to be switchable using the
> CONFIG_SECURITY_FILE_CAPABILITIES option.

(note: defconfig has CONFIG_SECURITY_FILE_CAPABILITIES=y)
text data bss dec hex filename
6805157 1018344 671900 8495401 81a129 obj64-defconfig/vmlinux
6805151 1018368 671900 8495419 81a13b obj64-defconfig-patch1/vmlinux
6805151 1018368 671900 8495419 81a13b obj64-defconfig-patch2/vmlinux
6804605 1018344 671900 8494849 819f01 obj64-nofcap/vmlinux
6804604 1018344 671900 8494848 819f00 obj64-nofcap-patch1/vmlinux
6805150 1018368 671900 8495418 81a13a obj64-nofcap-patch2/vmlinux

The last 2 show the real diff now, add 570 bytes by effectively forcing
CONFIG_SECURITY_FILE_CAPABILITIES on.

What is being done to enable userspace in distros to make those 570
bytes generally useful?

thanks,
-chris
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