Bug 256728 - rc.subr: ${name}_user uses "su -m" that invokes root shell instead of /bin/sh
Summary: rc.subr: ${name}_user uses "su -m" that invokes root shell instead of /bin/sh
Status: Open
Alias: None
Product: Base System
Classification: Unclassified
Component: conf (show other bugs)
Version: Unspecified
Hardware: Any Any
: --- Affects Some People
Assignee: freebsd-rc (Nobody)
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2021-06-20 10:02 UTC by Eugene Grosbein
Modified: 2021-12-10 23:14 UTC (History)
2 users (show)

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Description Eugene Grosbein freebsd_committer freebsd_triage 2021-06-20 10:02:32 UTC 
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.
Comment 1 Mateusz Piotrowski freebsd_committer freebsd_triage 2021-12-10 23:14:30 UTC 
The default root shell is now /bin/sh. It makes the issue a bit less pressing for new releases. The problem is still that users don't expect the choice of the interactive root shell to impact their rc service scripts...