Messages in this thread | | | Date | Wed, 15 Dec 2010 11:04:46 +0530 | From | "Suzuki K. Poulose" <> | Subject | Re: [RFC] [Patch 0/21] Non disruptive application core dump infrastructure |
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On Tue, 14 Dec 2010 07:49:37 -0800 Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Tue, Dec 14, 2010 at 1:52 AM, Suzuki K. Poulose <suzuki@in.ibm.com> wrote: > > > > This is series of patches implementing an infrastructure for capturing the core > > of an application without disrupting its process semantics. > > > > The infrastructure makes use of the freezer subsystem in kernel to freeze the > > threads and then collect the information to generate the core. > > This seems to be a fundamentally flawed approach. > > From a security standpoint, it looks like a total disaster. A frozen > process is really hard to get rid of, so it looks like an obvious DoS > attack to just create lots of processes, then sneakily freeze them > all, and then laugh at the poor system admin who has no idea what's > going on. While frozen, the things are basically unkillable but look > entirely normal, no?
You are right. We need a simple mechanism to hold the threads, so that we could collect the register information of the process without affecting its process semantics (eg, signals etc.). The suggestion by Kamezawa-san -a freeze state variant which allows SIGKILL - is one possibility.
I'd be very glad not using the freezer if there is a neat way to accomplish this without the undesired side effects. Tejun's ptrace enhancement would still require a userland program to control it(gcore); something contained in the kernel would be ideal.
Thanks
Suzuki
> > Linus
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