Drop daemon privilegies

[Denys Vlasenko]

On Monday 28 November 2011 06:52, Brilliantov Kirill Vladimirovich wrote:
> Hello!
> I run syslogd with system and found this:
> Jan  1 00:00:06 arm user.err monitor: Run drop_root, user monitor, errno 
> 0 (Success)
> Jan  1 00:00:06 arm daemon.crit mini_httpd[296]: socket :: - Address 
> family not supported by protocol
> Jan  1 00:00:06 arm user.err monitor: After getpwnam, uid = 100, gid = 
> 100, errno 0 (Success)
> Jan  1 00:00:06 arm user.err monitor: After setGID, r = 0, errno 0 (Success)
> Jan  1 00:00:06 arm user.err monitor: After setUID, r = 0, errno 0 (Success)

setgid/setuid worked.

> Jan  1 00:00:06 arm user.err monitor: Can't run in daemon mode, errno 13 
> (Permission denied)

Where this message comes from? Can you show C code which generates it
(and immediately preceding code too)?
What operation was attempted which ended with EPERM?


> But if I run daemon after manual all ok and in /var/log/messages I see this:
> Jan  1 00:02:46 arm user.err monitor: Run drop_root, user monitor, errno 
> 0 (Success)
> Jan  1 00:02:46 arm user.err monitor: After getpwnam, uid = 100, gid = 
> 100, errno 0 (Success)
> Jan  1 00:02:46 arm user.err monitor: After setGID, r = 0, errno 0 (Success)
> Jan  1 00:02:46 arm user.err monitor: After setUID, r = 0, errno 0 (Success)
> Jan  1 00:02:46 arm user.info monitor: daemon started, pid-file 
> /var/run/monitd.pid, PID 324
> Jan  1 00:02:46 arm user.info monitor: Ready to send message
> 
>