Date: Mon, 27 Feb 2012 22:34:25 -0800 From: Julian Elischer <julian@freebsd.org> To: Konstantin Belousov <kostikbel@gmail.com> Cc: Mikolaj Golub <trociny@freebsd.org>, svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Pawel Jakub Dawidek <pjd@freebsd.org> Subject: Re: svn commit: r232181 - in head/sys: kern sys Message-ID: <4F4C7571.7010407@freebsd.org> In-Reply-To: <20120227092951.GB55074@deviant.kiev.zoral.com.ua> References: <201202261425.q1QEPm9g069102@svn.freebsd.org> <20120227082811.GC1363@garage.freebsd.pl> <864nucd5jc.fsf@in138.ua3> <20120227092951.GB55074@deviant.kiev.zoral.com.ua>
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On 2/27/12 1:29 AM, Konstantin Belousov wrote: > On Mon, Feb 27, 2012 at 10:49:59AM +0200, Mikolaj Golub wrote: >> On Mon, 27 Feb 2012 09:28:11 +0100 Pawel Jakub Dawidek wrote: >> >> PJD> On Sun, Feb 26, 2012 at 02:25:48PM +0000, Mikolaj Golub wrote: >> >> Author: trociny >> >> Date: Sun Feb 26 14:25:48 2012 >> >> New Revision: 232181 >> >> URL: http://svn.freebsd.org/changeset/base/232181 >> >> >> >> Log: >> >> Add sysctl to retrieve or set umask of another process. >> >> PJD> "set umask of another process"? This seems... weird. What's the purpose >> PJD> of this change? >> >> When we were discussing this with Kostik and Robert, and I asked if it could >> be useful to have the sysctl rw, Kostik described a real situation when he had >> had to change umask of another process: umask had not been set properly on an >> aplication start but it could not be restarted until the end of the day. >> Kostik was able to fix it using gdb but having an easier way looked useful. > kgdb, not gdb. > > It is indeed possible to write a ptrace-based utility that inject a code > payload that would change umask. Since this is very risky but indeed possible, > having the straighforward kernel facility is justified. Why not have a sysctl to change a process' uid, cwd, memory limits, etc. etc. I don't think this belongs in the kernel by default. It's not exactl a call for backout but It's teh next thing short of that. a call for "do you REALLY think we need this particular specific case catered for?" Julian > Patch puts the same restrictions on the caller as ptrace().
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