Read-only signingKeyLocation file

[SimonSapin]

On a macOS worker, in an attempt to reduce unneeded permissions given to tasks, I tried to make as many configuration files as possible owned by root with the user running generic-worker only granted read accoss through a Unix group.

This fails, I assume because generic-worker tries to take ownership of the file configured through signingKeyLocation:

generic-worker/chain_of_trust_all-unix-style.go

Lines 42 to 46 in 2b70c93

	err = os.Chown(
	config.SigningKeyLocation,
	uid,
	gid,
	)

2018/11/12 14:12:50  *********** PANIC occurred! *********** 
2018/11/12 14:12:50 chown /etc/generic-worker/key: operation not permitted

Would it be acceptable to not try to take ownership and only check that the file is not world-readable?

[petemoore]

@SimonSapin I think the solution for this will be to use the multiuser engine for macOS, which finally has been created. This works just like the Windows releases, and creates task users on the fly for the tasks, but the generic-worker runs as root. There are some setup/installation instructions here. Let me know if you'd like any assistance/guidance etc.