syscalls/fork.c

   1 /*
   2    int sys_fork(struct pt_regs *regs)
   3  */
   4 #include <sys/wait.h>
   5 #include <stdlib.h>
   6 #include <unistd.h>
   7 #include "pids.h"
   8 #include "sanitise.h"
   9 #include "shm.h"
  10 #include "trinity.h"
  11
  12 /*
  13  * Because we don't want to forkbomb, we don't really do anything in the child process.
  14  * We only actually do a fork at all on the off-chance that it might trigger some oddness
  15  * in the VMAs we've created when we COW.
  16  *
  17  * TODO: Maybe do some dirty_mapping calls in the child ?
  18  * TODO: Maybe we could enforce an upper limit on the child count before we fork,
  19  *        and keep track of them using handle_child ?
  20  */
  21
  22 static void post_fork(int childno)
  23 {
  24         pid_t pid;
  25
  26         pid = shm->syscall[childno].retval;
  27         if (pid == 0) {
  28                 // child
  29                 sleep(1);
  30                 _exit(EXIT_SUCCESS);
  31         } else {
  32                 __unused__ int ret;
  33
  34                 while (pid_alive(pid)) {
  35                         int status;
  36                         ret = waitpid(pid, &status, WUNTRACED | WCONTINUED | WNOHANG);
  37                 }
  38         }
  39 }
  40
  41 struct syscallentry syscall_fork = {
  42         .name = "fork",
  43         .num_args = 0,
  44         .flags = AVOID_SYSCALL, // No args to fuzz, confuses fuzzer
  45         .post = post_fork,
  46 };