1# Linux PID Namespace Support 2 3The [LinuxSUIDSandbox](suid_sandbox.md) currently relies on support for 4the `CLONE_NEWPID` flag in Linux's 5[clone() system call](http://www.kernel.org/doc/man-pages/online/pages/man2/clone.2.html). 6You can check whether your system supports PID namespaces with the code below, 7which must be run as root: 8 9```c 10#define _GNU_SOURCE 11#include <unistd.h> 12#include <sched.h> 13#include <stdio.h> 14#include <sys/wait.h> 15 16#if !defined(CLONE_NEWPID) 17#define CLONE_NEWPID 0x20000000 18#endif 19 20int worker(void* arg) { 21 const pid_t pid = getpid(); 22 if (pid == 1) { 23 printf("PID namespaces are working\n"); 24 } else { 25 printf("PID namespaces ARE NOT working. Child pid: %d\n", pid); 26 } 27 28 return 0; 29} 30 31int main() { 32 if (getuid()) { 33 fprintf(stderr, "Must be run as root.\n"); 34 return 1; 35 } 36 37 char stack[8192]; 38 const pid_t child = clone(worker, stack + sizeof(stack), CLONE_NEWPID, NULL); 39 if (child == -1) { 40 perror("clone"); 41 fprintf(stderr, "Clone failed. PID namespaces ARE NOT supported\n"); 42 } 43 44 waitpid(child, NULL, 0); 45 46 return 0; 47} 48``` 49