[OE-core] [PATCH 4/8] busybox: add the ability to split the busybox binary

[Bernhard Reutner-Fischer]

On 13 June 2013 08:46, ChenQi <Qi.Chen at windriver.com> wrote:
> On 06/12/2013 04:26 AM, Bernhard Reutner-Fischer wrote:
>>
>> On Fri, Jun 07, 2013 at 02:13:58PM +0800, Qi.Chen at windriver.com wrote:

> Hi Bernhard,
>
> Thank you very much for your review and suggestions!
> I went through your methods below very carefully and I tried your patch out.
>
> Here are two problems.
>
> 1) The config_list.suid could be derived by renaming the `original
> suid_config_list' file, but what about the config_list.nosuid? We have a
> suid_config_list, because compared with the non-suid apps, the amount of
> config items for suid apps or related to suid apps are relatively small. It
> seems that config_list.nosuid will be a very long list.

yes. You can derive the nosuid by subtracting the suid from the full .config.
If that is inconvenient, see the attached on top to generate both
busybox.cfg.nosuid and busybox.cfg.suid .
see below.
>
> 2) Your patch in the attachment worked out well. `make busybox.applets.suid'
> generates a file named busybox.applets.suid which contains the following
> config items.
> CONFIG_LOGIN
> CONFIG_PASSWD
> CONFIG_FEATURE_PASSWD_WEAK_CHECK
> CONFIG_SU
> CONFIG_FEATURE_SU_SYSLOG
> CONFIG_FEATURE_SU_CHECKS_SHELLS
> CONFIG_VLOCK
> CONFIG_FINDFS
> CONFIG_MOUNT
> CONFIG_FEATURE_MOUNT_FAKE
> CONFIG_FEATURE_MOUNT_VERBOSE
> CONFIG_FEATURE_MOUNT_LABEL
> CONFIG_FEATURE_MOUNT_CIFS
> CONFIG_FEATURE_MOUNT_FLAGS
> CONFIG_FEATURE_MOUNT_FSTAB
> CONFIG_FEATURE_MOUNT_LOOP
> CONFIG_FEATURE_MOUNT_LOOP_CREATE
> CONFIG_CRONTAB
> CONFIG_WALL
> CONFIG_PING
> CONFIG_PING6
> CONFIG_TRACEROUTE
> CONFIG_TRACEROUTE6
> CONFIG_FEATURE_TRACEROUTE_VERBOSE
>
> You see, this is a subset of the suid_config_list. As stated in the file's
> comments, part of the list is obtained from a command, and part of it is
> obtained by manually examine the Config.in files to find out the config
> items that are related to suid apps.

Yes, i know. Do you have suggestions there?
I think what we/you want is to build:
- busybox.suid with all nosuid *applets* turned off, but the
non-applet CONFIG_ as per full.config
- busybox.nosuid with all suid *applets* turned off, but the
non-applet CONFIG_ as per full.config

I.e. take busybox.cfg.nosuid (contains only applets), take
busybox.cfg.suid (also contains only applets)
subtract these -> non-applet_part_of_full.config.
merge non-applet_part_of_full.config + suid -> bb.suid
merge non-applet_part_of_full.config + nosuid -> bb.nosuid

Didn't try that, but you get the idea.
Would that work out for you?

cheers,
>
> Best Regards,
> Chen Qi
>
>> cat .config > .config-oe-full
>> # it would be nice to 'for s in suid nosuid'
>> # but that would mean operating on ${s}_config_list which bitbake (IIRC)
>> # ruins. Better rename the files to config_list.suid to be able to loop.
>> #
>> for s in suid nosuid; do
>>    egrep ^CONFIG_ ${WORKDIR}/config_list.$s | while read i; do
>>      grep -w "$i" .config
>>    done > .config.$s
>>
>>    # populate the config, default everything else to no
>>    KCONFIG_ALLCONFIG=config.$s make allnoconfig
>>    oe_runmake busybox_unstripped busybox.links
>>    mv busybox_unstripped busybox.$s
>>    mv busybox.links busybox.links.$s
>> done
>> cat .config-oe-full > .config
>>
>> I would much prefer to make the generation of the suid cfg stuff more
>> robust. Could you live with the attached helper thing (untested)?
>> That would make it a prepended oe_runmake busybox.applets.suid to
>> generate the list busybox.applets.suid. If that suits your needs we can
>> apply it to busybox for general use..
>> The other possibility is, obviously, to fit all this in busybox' build
>> itself, but given that we do have a seemingly working, bugless suid
>> handling this might be better suited to be dealt with by the user as you
>> suggest here.
>>
>> Thoughts?
>> thanks,
>>>
>>> +               cp .config .config.orig
>>> +               oe_runmake allnoconfig
>>> +               cp .config .config.allno
>>> +               for item in `grep 'CONFIG_' ${WORKDIR}/suid_config_list`;
>>> do
>>> +                       echo "# $item is not set" >> .config.nosuid.tmp
>>> +                       grep -w "$item" .config.orig >> .config.suid.tmp
>>> +               done
>>> +               merge_config.sh -m .config.orig .config.nosuid.tmp
>>> +               cp .config .config.nosuid
>>> +               merge_config.sh -m .config.allno .config.suid.tmp
>>> +               cp .config .config.suid
>>> +
>>> +               # compile with no suid apps
>>> +               cp .config.nosuid .config
>>> +               oe_runmake busybox_unstripped
>>> +               cp busybox_unstripped busybox.nosuid
>>> +               oe_runmake busybox.links
>>> +               cp busybox.links busybox.links.nosuid
>>> +
>>> +               # compile with suid apps
>>> +               cp .config.suid .config
>>> +               oe_runmake busybox_unstripped
>>> +               cp busybox_unstripped busybox.suid
>>> +               oe_runmake busybox.links
>>> +               cp busybox.links busybox.links.suid
>>> +
>>> +               # copy .config.orig back to .config, because the install
>>> process may check this file
>>> +               cp .config.orig .config
>>> +
>>> +               # cleanup
>>> +               rm .config.orig .config.nosuid.tmp .config.allno
>>> .config.suid.tmp .config.nosuid .config.suid
>>> +       else
>>> +               oe_runmake busybox_unstripped
>>> +               cp busybox_unstripped busybox
>>> +               oe_runmake busybox.links
>>> +       fi
>>> }
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