#include <signal.h>
#include <libproc.h>
#include <sys/sysctl.h>
#include <darwintest.h>
// rdar://128791723
// Ensure pidversion always changes across exec
static int32_t
get_pidversion_for_pid(pid_t pid)
{
struct proc_bsdinfowithuniqid bsd_info;
int ret = proc_pidinfo(pid, PROC_PIDT_BSDINFOWITHUNIQID, 0, &bsd_info, sizeof(bsd_info));
T_ASSERT_EQ((unsigned long)ret, sizeof(bsd_info), "PROC_PIDT_BSDINFOWITHUNIQID");
return bsd_info.p_uniqidentifier.p_idversion;
}
T_DECL(ensure_pidversion_changes_on_exec,
"Ensure pidversion always changes across exec, even when groomed not to",
T_META_NAMESPACE("xnu.exec"),
T_META_TAG_VM_PREFERRED
) {
T_SETUPBEGIN;
// Given we exec a helper program (in a forked child, so this runner can stick around)
// (And we set up some resources to communicate with the forked process)
int pipefd[2];
T_ASSERT_POSIX_SUCCESS(pipe(pipefd), "pipe");
pid_t forked_pid = fork();
T_ASSERT_POSIX_SUCCESS(forked_pid, "fork");
if (forked_pid == 0) {
close(pipefd[0]);
// And we keep track of our current pidversion
int32_t forked_proc_pidv = get_pidversion_for_pid(getpid());
// And we ask the kernel to groom things such that `nextpidversion == current_proc->p_idversion + 1`
int64_t val = 0;
size_t val_len = sizeof(val);
sysctlbyname("debug.test.setup_ensure_pidversion_changes_on_exec", &val, &val_len, &val, sizeof(val));
// (And we send the parent's pidversion back to the test runner, for comparison with the exec'd process)
T_ASSERT_POSIX_SUCCESS(write(pipefd[1], (void*)&forked_proc_pidv, sizeof(forked_proc_pidv)), "write");
T_ASSERT_POSIX_SUCCESS(close(pipefd[1]), "close");
// When I exec a child
// (Which spins forever, so we can poke it)
char *args[4];
char *tail_path = "/usr/bin/tail";
args[0] = tail_path;
args[1] = "-f";
args[2] = "/dev/null";
args[3] = NULL;
execv(tail_path, args);
T_FAIL("execve() failed");
}
T_ASSERT_POSIX_SUCCESS(close(pipefd[1]), "close");
// (And we read the parent's pidversion from our forked counterpart, for comparison with the exec'd process)
int32_t forked_proc_pidversion;
T_ASSERT_POSIX_SUCCESS(read(pipefd[0], &forked_proc_pidversion, sizeof(forked_proc_pidversion)), "read");
T_ASSERT_POSIX_SUCCESS(close(pipefd[0]), "close");
// (Give the forked process a moment to exec().)
// (To get rid of this, we could exec something controlled that signals a semaphore.)
sleep(1);
T_SETUPEND;
// And I interrogate the pidversion of the exec'd process
int32_t exec_proc_pidversion = get_pidversion_for_pid(forked_pid);
// Then the pidversion should NOT be reused, despite our grooming
T_ASSERT_NE(exec_proc_pidversion, forked_proc_pidversion, "Prevent pidversion reuse");
// Cleanup: kill our errant child
T_SETUPBEGIN;
T_ASSERT_POSIX_SUCCESS(kill(forked_pid, SIGKILL), "kill");
T_SETUPEND;
}