Re: + core_pattern-set-core-helpers-root-and-namespace-to-crashing-process .patch added to -mm tree

[ebiederm@xmission.com (Eric W. Biederman)]

Neil Horman <nhorman@tuxdriver.com> writes:

> On Tue, Dec 18, 2012 at 12:45:18PM -0800, Eric W. Biederman wrote:

>> The code for setns to change the pid namespace just merged.
>> 
> Can you post a link to the merge commit for reference so I can take a look at
> it?

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commit;h=6a2b60b17b3e48a418695a94bd2420f6ab32e519

>> If we just want one pattern we should be able to to robustly implement
>> this in userspace with the existing functionality.  With the caveat that
>> we need to get some pid namespace and user namespace bugs in the core
>> pattern generation fixed.  But we need to fix those bugs anyway.
>> 
> Then perhaps the right thing to do here is in fact just make core_pattern a
> per-namespace sysctl.  I only took a brief look, but I was unable to find an
> example of such a per-namespace systctl.  Do we already have the infrastructure
> to do such a thing?  I didn't think we did.

We do have the infrastructure for a per namespace sysctls.  Right now we
only have per network namespace sysctls.  It is on my wish list to use
the infrastructure a little more extensively and convert /proc/sys into
a symlink to /proc/<pid>/sys and reduce the amount of magic in /proc for
sysctls.

We also have per namespace sysctls that do magic based upon current.
Since that pattern is has more magic I don't recommend it over the long
term.

Of course there is the question which namespace the sysctl should be
tied to, and what the other namespaces should be set to.  Shrug.

Eric