IOError - cannot create file (linux daemon-invoked script)

Nobody nobody at nowhere.com
Tue Jan 5 19:58:23 CET 2010


On Mon, 04 Jan 2010 21:30:31 -0800, cassiope wrote:

> One more tidbit observed: my last note, that it works when using
> seteuid/setegid?
> Well - that only applies if the daemon is running under strace (!).
> It fails
> if started directly by root, or if the strace session has ended,
> leaving the
> main body of the daemon running in its normal headless manner.
> 
> I wonder if running under "strace -f" - might setegid/seteuid be
> prevented from
> having their normal effect?

Possibly. The ptrace() syscall on which strace depends will fail if you
try to trace a "privileged" process and you aren't root, so it's possible
that a ptrace()d process will refuse to become privileged.

Here, "privileged" includes a process which has changed any of its UIDs or
GIDs (this prevents a normal user from tracing, killing, etc an otherwise
privileged process which has switched to the user's UID for the time being).




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