On 05/07/2011 04:24 AM, Eric W. Biederman wrote:
With the networking stack today there is demand to handle multiple network stacks at a time. Not in the context of containers but in the context of people doing interesting things with routing. There is also demand in the context of containers to have an efficient way to execute some code in the container itself. If nothing else it is very useful ad a debugging technique. Both problems can be solved by starting some form of login daemon in the namespaces people want access to, or you can play games by ptracing a process and getting the traced process to do things you want it to do. However it turns out that a login daemon or a ptrace puppet controller are more code, they are more prone to failure, and generally they are less efficient than simply changing the namespace of a process to a specified one. Pieces of this puzzle can also be solved by instead of coming up with a general purpose system call coming up with targed system calls perhaps socketat that solve a subset of the larger problem. Overall that appears to be more work for less reward. int setns(int fd, int nstype); The fd argument is a file descriptor referring to a proc file of the namespace you want to switch the process to. In the setns system call the nstype is 0 or specifies an clone flag of the namespace you intend to change to prevent changing a namespace unintentionally. v2: Most of the architecture support added by Daniel Lezcano<dlezcano@xxxxxxxxxx> v3: ported to v2.6.36-rc4 by: Eric W. Biederman<ebiederm@xxxxxxxxxxxx> v4: Moved wiring up of the system call to another patch Signed-off-by: Eric W. Biederman<ebiederm@xxxxxxxxxxxx> ---
Acked-by: Daniel Lezcano <daniel.lezcano@xxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
