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

[Ben Stuyts <ben@altesco.nl>]

Hi David :)

> On 26 Jul 2016, at 16:00, David Jander <david@protonic.nl> wrote:
> 
> 
> Dear Guillermo,
> 
> Thanks for your reply.
> 
> 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…

Perhaps a Q&D solution would be to create a symbolic link from /root to /home (or v.v.)? Then at least whatever mechanism is used, it would end up pointing to the same directory.

Kind regards,
Ben

> 
> 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.
> 
>> Guillermo
>> 
>> 2016-07-26 14:09 GMT+02:00 David Jander <david.jander@protonic.nl>:
>> 
>>> 
>>> Dear Michael,
>>> 
>>> I have prepared a patch against ptxdist git for the package systemd-230.
>>> I would like to know the right way to proceed to submit this patch, since
>>> I am
>>> not a ptxdist developer and am not familiar with how tools like
>>> git-ptxdist-patch are supposed to be used (to generate the correct series
>>> file
>>> in this case).
>>> 
>>> The patch is really trivial and I don't know if it deserves so much work (I
>>> suspect that I have to clone the git repository of systemd first and apply
>>> all
>>> patches there, right?).
>>> 
>>> What I am trying to fix here is the notion that systemd has about what the
>>> $HOME directory of the user 'root' (uid=0) should be. As it seems, in
>>> systemd
>>> this is hardcoded to be "/root", while ptxdist by default seems to insist
>>> in
>>> "/home" for some reason (according to shipped /etc/passwd). Here's the gist
>>> of what the patch does:
>>> 
>>> --- systemd-230.orig/src/basic/user-util.c
>>> +++ systemd-230/src/basic/user-util.c
>>> @@ -123,7 +123,7 @@ int get_user_creds(
>>>                         *gid = 0;
>>> 
>>>                 if (home)
>>> -                        *home = "/root";
>>> +                        *home = "/home";
>>> 
>>>                 if (shell)
>>>                         *shell = "/bin/sh";
>>> 
>>> Without this patch, things like services that declare "User=root" get
>>> screwed
>>> up with the wrong home directory for example.
>>> 
>>> Thanks.
>>> 
>>> Best regards,
>>> 
>>> --
>>> David Jander
>>> Protonic Holland.
>>> 
>>> _______________________________________________
>>> ptxdist mailing list
>>> ptxdist@pengutronix.de  
>> 
>> 
>> 
>> 
> 
> Best regards,
> 
> -- 
> David Jander
> Protonic Holland.
> tel.: +31 (0) 229 212928
> fax.: +31 (0) 229 210930
> Factorij 36 / 1689 AL Zwaag
> 
> _______________________________________________
> ptxdist mailing list
> ptxdist@pengutronix.de
> 


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