[Bug 256728] rc.subr: ${name}_user uses "su -m" that invokes root shell instead of /bin/sh

From: <bugzilla-noreply_at_freebsd.org>
Date: Sun, 20 Jun 2021 10:02:32 +0000
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=256728

            Bug ID: 256728
           Summary: rc.subr: ${name}_user uses "su -m" that invokes root
                    shell instead of /bin/sh
           Product: Ports & Packages
           Version: Latest
          Hardware: Any
                OS: Any
            Status: New
          Severity: Affects Some People
          Priority: ---
         Component: Ports Framework
          Assignee: portmgr_at_FreeBSD.org
          Reporter: eugen_at_freebsd.org
                CC: ports-bugs_at_FreeBSD.org

The port net/p2p/transmission-daemon is an example of service that utilizes
<name>_user rc.conf setting. Also, it supports writing debugging logs to
pre-opened (redirected to a file) STDERR by means of environment variable
TR_DEBUG_FD=2 but our framework uses "su -m" for such services executing root
shell that defaults to stock csh (contrib/tcsh) that closes its file descriptor
2 at start.

Note there is some kind of work-around if we do not use login classes and/or
limits for the service, then add to /etc/rc.conf

transmission_chroot="/"

So "chroot -u transmission /" is used to substitute user instead of "su -m" and
chroot(8) is documented not to use root shell but SHELL=/bin/sh. And /bin/sh
keeps redirected STDERR open in such case.

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Received on Sun Jun 20 2021 - 10:02:32 UTC

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