Re: [PATCH v3] kernel: Conditionally support non-root users, groups and capabilities

[Geert Uytterhoeven]

Hi Iulia,

On Fri, Feb 6, 2015 at 2:10 PM, Iulia Manda <iulia.manda21@xxxxxxxxx> wrote:
> On 6 February 2015 at 02:03, Iulia Manda <iulia.manda21@xxxxxxxxx> wrote:
>> There are a lot of embedded systems that run most or all of their functionality
>> in init, running as root:root. For these systems, supporting multiple users is
>> not necessary.
>>
>> This patch adds a new symbol, CONFIG_MULTIUSER, that makes support for non-root
>> users, non-root groups, and capabilities optional. It is enabled under
>> CONFIG_EXPERT menu.
>>
>> When this symbol is not defined, UID and GID are zero in any possible case
>> and processes always have all capabilities.
>>
>> The following syscalls are compiled out: setuid, setregid, setgid,
>> setreuid, setresuid, getresuid, setresgid, getresgid, setgroups, getgroups,
>> setfsuid, setfsgid, capget, capset.
>>
>> Also, groups.c is compiled out completely.
>>
>> This change saves about 25 KB on a defconfig build.
>>
>> The kernel was booted in Qemu. All the common functionalities work. Adding
>> users/groups is not possible, failing with -ENOSYS.
>>
>> Bloat-o-meter output:
>> add/remove: 7/87 grow/shrink: 19/397 up/down: 1675/-26325 (-24650)
>>
>
> Forgot to add:
>
> Signed-off-by: Iulia Manda <iulia.manda21@xxxxxxxxx>
> Reviewed-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
>
>> ---
>> Changes since v2:
>>         - rename symbol;
>>         - make SECURITY dependent on MULTIUSER
>>
>
> + make symbols depend on MULTIUSER instead of selecting it.

Thanks for the update!

Acked-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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