non-root process and PID files
vance at aurema.com
Wed Oct 29 16:32:02 PST 2003
On Mon, Oct 27, 2003 at 10:31:18AM -0500, Dan Langille wrote:
>If a process starts up and does a setuid, should it be writing the
>PID file before or after the setuid?
>Two methods exists AFAIK:
>1 - write your PID immediately, and the file is chown root:wheel
>2 - write your PID to /var/run/myapp/myapp.pid where /var/run/myapp/
> is chown myapp:myapp
>Of the two, I think #1 is cleaner as it does not require another
>directory with special permissions.
You can already mark a fd 'close on exec'.
May I suggest a different feature: the ability to mark an open file
(not just its fd) 'remove on close', with permission checked at mark
time rather than close time (this status forgotten if not permitted
when set) and the unlink actually done at close time only if the file
has exactly one link and one open file instance at that time.
That way your server can
start as root
open file to write/update
downgrade/reopen file to readonly
mark remove on close
Or you could call it a future unlink.
I'm sure there are holes in it, and I won't claim to have tried it, ...
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