Equivalent of setns() in jails

[suresh.pujar]

Hello,

Looking for linux setns() like facility from freebsd jail - where using setns() a different threads of a process can switch to different namespaces where as, using jail, once the first thread calls jail_attach() whole process(including other threads) gets into the same jail as entered by first thread. And any subsequent attempt to call jail_attach() from other threads would fail with "Invalid argument". Understood the reason for this failure being, once the process gets into a jail(JID#1 below), it can't find jails defined (with JID#1 and JID#2) the system.

Now, Is there a way(libc/system call) for these threads to reassociate with jails similar to setns? Like thread1 should operate on Jail#1 and Thread2 on Jail#2 at any point in time.

# jls
   JID  IP Address      Hostname                      Path
     1                  bsd1                        /
     2                  bsd1                        /

bsd1: # ./jlattach
Starting threads..
Inside Thread1        ==> This thread could attach to Jail#1 (Now, whole process switched to Jail#1)
Inside Thread2
Attach Failed2: Invalid argument   ==> This fails as process already entered Jail#1 and can't find Jail#2 defined inside Jail#1
Attach Failed - Main Thread: Invalid argument ==> This also fails, main thread attempts to attach to Jail#1 from Jail#1
Threads exit..

Test Code for above: (To compile: cc file.c -lpthread -o jlattach)

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <sys/param.h>
#include <sys/jail.h>
#include <netinet/in.h>
#include <string.h>

void *Thread1(void *argp)
{
        printf("Inside Thread1\n");
        if(jail_attach(1)<0)
        perror("Attach Failed1");
        sleep(5);

        return NULL;

}

void *Thread2(void *argp)
{
        printf("Inside Thread2\n");
        if(jail_attach(2)<0)
        perror("Attach Failed2");
        sleep(6);

        return NULL;

}

int main()
{
        pthread_t thread_id[2];

        printf("Starting threads..\n");
        pthread_create(&thread_id[0], NULL, Thread1, NULL);
        pthread_create(&thread_id[1], NULL, Thread2, NULL);
        pthread_join(thread_id[0], NULL);
        pthread_join(thread_id[1], NULL);

        if(jail_attach(1)<0)
        perror("Attach Failed - Main Thread");

        printf("Threads exit..\n");
        exit(0);
}