[LightDM] Problem with LightDM on Solaris build

[Raimund Steger]

Hi,

On 2011-11-29 18:07, Guido Berhoerster wrote:
> [...]
>>
>> Is the use of these functions necessary?  Would it make sense to #ifdef
>> the code so it can also build and work on Solaris?  Any advice about how
>> to make this code more portable would be appreciated.
>
> privileges_drop() is being called from the lightdm daemon running
> with root privileges, so manipulating real and effective uid/gid
> without side effects on the saved uid is possible via procfs, ie.
> /proc/<pid>/ctl. Restoring them later in privileges_reclaim
> should be possible by first calling setuid() for setting the
> effective to the saved and then setreuid() for setting the real
> to the effective uid (and analoguosly calling setgid()/setregid()
> for restoring the effective/real gid).

I wonder, is it even necessary in this situation to set the real user ID?

Wouldn't setegid()/seteuid() (first to the user's, then back to 0) 
suffice for filesystem operations?

-Raimund

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