[Devel] Re: [PATCH 11/15] Signal semantics

[sukadev at us.ibm.com]

Serge E. Hallyn [serue at us.ibm.com] wrote:
| Quoting sukadev at us.ibm.com (sukadev at us.ibm.com):
| > Pavel Emelianov [xemul at openvz.org] wrote:
| > | Oleg Nesterov wrote:
| > | >(What about ptrace_attach() btw? If it is possible to send a signal to init
| > | > from the "parent" namespace, perhaps it makes sense to allow ptracing as
| > | > well).
| > | 
| > | ptracing of tasks fro different namespaces is not possible at all, since
| > | strace utility determines the fork()-ed child pid from the parent's eax
| > | register, which would contain the pid value as this parent sees his child.
| > | But if the strace is in different namespace - it won't be able to find
| > | this child with the pid value from parent's eax.
| > | 
| > | Maybe it's worth disabling cross-namespaces ptracing...
| > 
| > I think so too. Its probably not a serious limitation ?
| 
| Several people think we will implement 'namespace entering' through a
| ptrace hack, where maybe the admin ptraces the init in a child pidns,
| makes it fork, and makes the child execute what it wants (i.e. ps -ef).
| 
| You're talking about killing that functionality?

No. I was only thinking in terms of debugging container init and missed
the namespace entering part.

Pavel, I am not sure I understand your comment about being unable to
ptrace() a child ns. 

BTW, I am able to gdb a process (incl container-init) from parent ns now.

| 
| -serge