Re: [PATCH 0/2] namespaces: log namespaces per task

On Mon, 2014-05-05 at 17:48 -0400, Richard Guy Briggs wrote: > On 14/05/05, Serge E. Hallyn wrote: > > Quoting James Bottomley (James.Bottomley(a)HansenPartnership.com): > > > On Tue, 2014-04-22 at 14:12 -0400, Richard Guy Briggs wrote: > > > > Questions: > > > > Is there a way to link serial numbers of namespaces involved in migration of a > > > > container to another kernel? (I had a brief look at CRIU.) Is there a unique > > > > identifier for each running instance of a kernel? Or at least some identifier > > > > within the container migration realm? > > > > > > Are you asking for a way of distinguishing an migrated container from an > > > unmigrated one? The answer is pretty much "no" because the job of > > > migration is to restore to the same state as much as possible. > > > > > > Reading between the lines, I think your goal is to correlate audit > > > information across a container migration, right? Ideally the management > > > system should be able to cough up an audit trail for a container > > > wherever it's running and however many times it's been migrated? > > > > > > In that case, I think your idea of a numeric serial number in a dense > > > range is wrong. Because the range is dense you're obviously never going > > > to be able to use the same serial number across a migration. However, > > > > Ah, but I was being silly before, we can actually address this pretty > > simply. If we just (for instance) add > > /proc/self/ns/{ic,mnt,net,pid,user,uts}_seq containing the serial number > > for the relevant ns for the task, then criu can dump this info at > > checkpoint. Then at restart it can dump an audit message per task and > > ns saying old_serial=%x,new_serial=%x. That way the audit log reader > > can if it cares keep track. > > This is the sort of idea I had in mind... OK, but I don't understand then why you need a serial number. There are plenty of things we preserve across a migration, like namespace name for instance. Could you explain what function it performs because I think I might be missing something.

James > > -serge > > > > (Another, more heavyweight approach would be to track all ns hierarchies > > and make the serial numbers per-namespace-instance. So my container's > > pidns serial might be 0x2, and if it clones a new pidns that would be > > "(0x2,0x1)" on the host, or just 0x1 inside the container. But we don't > > need that if the simple userspace approach suffices) > > This sounds manageable... > > - RGB > > -- > Richard Guy Briggs <rbriggs(a)redhat.com&gt; > Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat > Remote, Ottawa, Canada > Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545