Update pam_zfs_key.c default path for FreeBSD

[eborisch]

As described in freebsd/freebsd-src#1305 : FreeBSD's installer defaults to zroot/home for user home directories.

For FreeBSD only, set the default prefix for pam_zfs_key to match.

Motivation and Context

This will resolve freebsd/freebsd-src#1305 : have the default for pam_zfs_key's home directory root match what FreeBSD installer sets it to.

Description

FreeBSD-only (ifdef-ed) change of the default (in the zfs tree) home location for pam_zfs_key.

How Has This Been Tested?

No testing of this minor change. pam_zfs_key isn't quite "ready for prime time" (IMHO) on FreeBSD, but this is one step towards that.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Quality assurance (non-breaking change which makes the code more robust against bugs)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.

[oshogbo]

Maybe this should be somehow configured instead of the hardcoded path?

[eborisch]

Maybe this should be somehow configured instead of the hardcoded path?

It is configurable with the homes= argument in the pam configuration; this is just setting the default (for FreeBSD) to match the FreeBSD installer’s default naming.

[amotin]

I can't say that I like this change of the default, since somebody might actually use the old name already, and they may end up in an inconvenient position. But if FreeBSD people wish to have this...

[behlendorf]

It'd be nice not to have a different defaults, but if it makes things simpler for the FreeBSD installer then I'm fine with it.

[behlendorf]

@eborisch please update the commit message with your signed-off-by, then this should be all set.

https://github.com/openzfs/zfs/actions/runs/16793233992/job/47558772845?pr=17600