Re: [ptxdist] Resend: Home dir fixup for root in systemd

[Artur Wiebe <artur@4wiebe.de>]

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Hi all,

to patch systemd to fit some "mistake" in ptxdist seems quite 
disproportionately.

It is much simpler to change home of root to /root by providing own 
/projectroot/etc/passwd then undoing a patch.

Oh, it was just a typo of Michael! Great!

Ialsovote for solution 1: set home for root to /root

Change PTXdist and all places in it that assume the $HOME=/home for root.

Best Regards,
Artur

Am 27.07.2016 um 10:55 schrieb David Jander:
> Dear Michael,
>
> On Wed, 27 Jul 2016 08:55:13 +0200
> Michael Olbrich <m.olbrich@pengutronix.de> wrote:
>
>> Hi,
>>
>> On Tue, Jul 26, 2016 at 04:00:34PM +0200, David Jander wrote:
>>> On Tue, 26 Jul 2016 15:19:59 +0200
>>> Guillermo Rodriguez Garcia <guille.rodriguez@gmail.com> wrote:
>>>    
>>>> Wouldn't it be easier to either use a custom /etc/passwd, or create a /root
>>>> dir in the filesystem ? That sounds better than patching systemd.
>>> Maybe it would be better to change the default /etc/passwd (and everywhere
>>> else) in ptxdist then...
>>>
>>> The problem is that what /etc/passwd says is mandatory. The home directory has
>>> a special meaning to the user. You can get to the home directory via $HOME
>>> passed in the environment, or via the NS-switch (getent) lookup. They are
>>> supposed to be the same.
>>> systemd has hardcoded defaults in source-code, which by definition is ugly as
>>> hell, but the reason is clearly to avoid potentially expensive, blocking
>>> NSS-lookups in the early boot stages, so it is understandable. It would be a
>>> lot better if there was some configuration setting read from a file I guess,
>>> but alas.
>>> On PTXdist now (with the default, shipped /etc/passwd), a user logging in as
>>> "root" via, say a serial console getty, will have a different $HOME than a
>>> systemd service started with User=root. This is bad, and can potentially do
>>> funny things people will not like.
>>> To solve the problem, there are really only two options AFAICS:
>>>
>>>   1.- Change PTXdist and all places in it that assume the $HOME=/home for root.
>>>   No idea how many places that are, nor how many users already depend on this
>>>   historic assumption.
>>>
>>> or
>>>
>>>   2.- Patch systemd to adapt to the reality of PTXdist.
>>>
>>> I agree that option 1 is probably better if PTXdist is more or less the only
>>> place on earth left where $HOME != /root for uid=0. Historically on Unix it
>>> used to be "/", but that is just way too ugly (guess where the name "root"
>>> came from?).
>>>
>>> Using a custom /etc/passwd is not an option, because the default PTXdist stays
>>> broken this way.
>>>
>>> Creating a /root dir is also broken, because like I explained above, the root
>>> user will become schizophrenic when logging in and running services from
>>> systemd alternately. Think about a user logging in, starting a tool that
>>> writes a config files to ~/.bla, and then configuring the same tool to run as a
>>> system service. I would (did!) get slightly mad when finding the tool to run
>>> with a totally different configuration in the latter case.
>> Unless someone comes up with a really good reason, then I think we should go
>> with option 2. I have actually considered making the change in the past
>> just to be consistent. But I never got around to do it.
>> I didn't notice this problem, probably because my rootfs is usually
>> read-only, and /root and /home are both empty.
>>
>> It would be great if some more people would speak up. Such a change can
>> potentially break things, so I'd like to know what others are thinking.
> Ok, just so we understand each other, you propose to go with my original patch
> in this case (i.e. patch systemd to assume $HOME=/home), right?
> In case nobody speaks up against it, will you pick it up as-is, or should I
> make a correct patch (i.e. learn how to properly use git-ptxdist-patch to
> generate a correct series file) and post it here?
>
> Best regards,
>


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