Bug#1110980: /var/lock/ is the standard interface for serial devices locks

[René]

Hello, if I set /var/lock/ to be writable only by the dialout group, can I update systemd without any problems, please? 

Best regards
René

On Wed, 13 Aug 2025 10:23:56 +0200 Marco d'Itri <md at linux.it> wrote:
> Package: systemd
> Version: 258~rc2-2
> Severity: critical
> 
> Control: forwarded -1 https://github.com/systemd/systemd/issues/38563
> 
> Breaks unrelated software.
> 
> /var/lock/ is not just the dumping ground for lock files of random 
> applications, but also the published interface for system-wide locks of 
> serial devices.
> 
> From section 5.9.1 of the FHS:
> 
>    Lock files should be stored within the /var/lock directory
>    structure.
> 
>    Lock files for devices and other resources shared by multiple
>    applications, such as the serial device lock files that were
>    originally found in either /usr/spool/locks or /usr/spool/uucp,
>    must now be stored in /var/lock. The naming convention which
>    must be used is "LCK.." followed by the base name of the
>    device. For example, to lock /dev/ttyS0 the file "LCK..ttyS0"
>    would be created. ^[43]
> 
> I think that this can be easily solved by making /run/lock/ owned by 
> group dialout.
> 
> -- 
> ciao,
> Marco