pkg/57847: unprivileged pkgsrc builds should be able to make privileged binary packages

[campbell+netbsd%mumble.net@localhost]

>Number:         57847
>Category:       pkg
>Synopsis:       unprivileged pkgsrc builds should be able to make privileged binary packages
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Jan 13 19:50:00 +0000 2024
>Originator:     Taylor R Campbell
>Release:        current
>Organization:
The pkgsrc privilegedation
>Environment:
>Description:
$ cd security/sudo
$ make show-var VARNAME=UNPRIVILEGED
yes
$ make package
=> Bootstrap dependency digest>=20211023: found digest-20220214
ERROR: This package is not available in unprivileged mode.

Although unprivileged pkgsrc can't _install_ privileged packages, i.e., packages with suid executables and similar, it should be able to _build_ them, e.g. with an mtree(8) input to pkg_create to record the privileged permissions.

Similarly, unprivileged builds mask some tools like `chown', replacing them by `true' in installed scripts, like pbulk's pkg-build script.  But you should be able to do unprivileged builds of such packages; the build process doesn't need to execute chown in order to bake it into a script.
>How-To-Repeat:
1. set UNPRIVILEGED=yes
2. build a privileged package like security/sudo
3. try to use a package that runs chown at runtime
>Fix:
Yes, please!