/* SPDX-License-Identifier: GPL-2.0 */
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <linux/types.h>
#include <pthread.h>
#include <sched.h>
#include <signal.h>
#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <syscall.h>
#include <sys/epoll.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>
#include "pidfd.h"
#include "../kselftest.h"
#define str(s) _str(s)
#define _str(s) #s
#define CHILD_THREAD_MIN_WAIT 3 /* seconds */
#define MAX_EVENTS 5
static bool have_pidfd_send_signal;
static pid_t pidfd_clone(int flags, int *pidfd, int (*fn)(void *))
{
size_t stack_size = 1024;
char *stack[1024] = { 0 };
#ifdef __ia64__
return __clone2(fn, stack, stack_size, flags | SIGCHLD, NULL, pidfd);
#else
return clone(fn, stack + stack_size, flags | SIGCHLD, NULL, pidfd);
#endif
}
static int signal_received;
static void set_signal_received_on_sigusr1(int sig)
{
if (sig == SIGUSR1)
signal_received = 1;
}
/*
* Straightforward test to see whether pidfd_send_signal() works is to send
* a signal to ourself.
*/
static int test_pidfd_send_signal_simple_success(void)
{
int pidfd, ret;
const char *test_name = "pidfd_send_signal send SIGUSR1";
if (!have_pidfd_send_signal) {
ksft_test_result_skip(
"%s test: pidfd_send_signal() syscall not supported\n",
test_name);
return 0;
}
pidfd = open("/proc/self", O_DIRECTORY | O_CLOEXEC);
if (pidfd < 0)
ksft_exit_fail_msg(
"%s test: Failed to open process file descriptor\n",
test_name);
signal(SIGUSR1, set_signal_received_on_sigusr1);
ret = sys_pidfd_send_signal(pidfd, SIGUSR1, NULL, 0);
close(pidfd);
if (ret < 0)
ksft_exit_fail_msg("%s test: Failed to send signal\n",
test_name);
if (signal_received != 1)
ksft_exit_fail_msg("%s test: Failed to receive signal\n",
test_name);
signal_received = 0;
ksft_test_result_pass("%s test: Sent signal\n", test_name);
return 0;
}
static int test_pidfd_send_signal_exited_fail(void)
{
int pidfd, ret, saved_errno;
char buf[256];
pid_t pid;
const char *test_name = "pidfd_send_signal signal exited process";
if (!have_pidfd_send_signal) {
ksft_test_result_skip(
"%s test: pidfd_send_signal() syscall not supported\n",
test_name);
return 0;
}
pid = fork();
if (pid < 0)
ksft_exit_fail_msg("%s test: Failed to create new process\n",
test_name);
if (pid == 0)
_exit(EXIT_SUCCESS);
snprintf(buf, sizeof(buf), "/proc/%d", pid);
pidfd = open(buf, O_DIRECTORY | O_CLOEXEC);
ret = wait_for_pid(pid);
ksft_print_msg("waitpid WEXITSTATUS=%d\n", ret);
if (pidfd < 0)
ksft_exit_fail_msg(
"%s test: Failed to open process file descriptor\n",
test_name);
ret = sys_pidfd_send_signal(pidfd, 0, NULL, 0);
saved_errno = errno;
close(pidfd);
if (ret == 0)
ksft_exit_fail_msg(
"%s test: Managed to send signal to process even though it should have failed\n",
test_name);
if (saved_errno != ESRCH)
ksft_exit_fail_msg(
"%s test: Expected to receive ESRCH as errno value but received %d instead\n",
test_name, saved_errno);
ksft_test_result_pass("%s test: Failed to send signal as expected\n",
test_name);
return 0;
}
/*
* Maximum number of cycles we allow. This is equivalent to PID_MAX_DEFAULT.
* If users set a higher limit or we have cycled PIDFD_MAX_DEFAULT number of
* times then we skip the test to not go into an infinite loop or block for a
* long time.
*/
#define PIDFD_MAX_DEFAULT 0x8000
static int test_pidfd_send_signal_recycled_pid_fail(void)
{
int i, ret;
pid_t pid1;
const char *test_name = "pidfd_send_signal signal recycled pid";
if (!have_pidfd_send_signal) {
ksft_test_result_skip(
"%s test: pidfd_send_signal() syscall not supported\n",
test_name);
return 0;
}
ret = unshare(CLONE_NEWPID);
if (ret < 0) {
if (errno == EPERM) {
ksft_test_result_skip("%s test: Unsharing pid namespace not permitted\n",
test_name);
return 0;
}
ksft_exit_fail_msg("%s test: Failed to unshare pid namespace\n",
test_name);
}
ret = unshare(CLONE_NEWNS);
if (ret < 0) {
if (errno == EPERM) {
ksft_test_result_skip("%s test: Unsharing mount namespace not permitted\n",
test_name);
return 0;
}
ksft_exit_fail_msg("%s test: Failed to unshare mount namespace\n",
test_name);
}
ret = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0);
if (ret < 0)
ksft_exit_fail_msg("%s test: Failed to remount / private\n",
test_name);
/* pid 1 in new pid namespace */
pid1 = fork();
if (pid1 < 0)
ksft_exit_fail_msg("%s test: Failed to create new process\n",
test_name);
if (pid1 == 0) {
char buf[256];
pid_t pid2;
int pidfd = -1;
(void)umount2("/proc", MNT_DETACH);
ret = mount("proc", "/proc", "proc", 0, NULL);
if (ret < 0)
_exit(PIDFD_ERROR);
/* grab pid PID_RECYCLE */
for (i = 0; i <= PIDFD_MAX_DEFAULT; i++) {
pid2 = fork();
if (pid2 < 0)
_exit(PIDFD_ERROR);
if (pid2 == 0)
_exit(PIDFD_PASS);
if (pid2 == PID_RECYCLE) {
snprintf(buf, sizeof(buf), "/proc/%d", pid2);
ksft_print_msg("pid to recycle is %d\n", pid2);
pidfd = open(buf, O_DIRECTORY | O_CLOEXEC);
}
if (wait_for_pid(pid2))
_exit(PIDFD_ERROR);
if (pid2 >= PID_RECYCLE)
break;
}
/*
* We want to be as predictable as we can so if we haven't been
* able to grab pid PID_RECYCLE skip the test.
*/
if (pid2 != PID_RECYCLE) {
/* skip test */
close(pidfd);
_exit(PIDFD_SKIP);
}
if (pidfd < 0)
_exit(PIDFD_ERROR);
for (i = 0; i <= PIDFD_MAX_DEFAULT; i++) {
char c;
int pipe_fds[2];
pid_t recycled_pid;
int child_ret = PIDFD_PASS;
ret = pipe2(pipe_fds, O_CLOEXEC);
if (ret < 0)
_exit(PIDFD_ERROR);
recycled_pid = fork();
if (recycled_pid < 0)
_exit(PIDFD_ERROR);
if (recycled_pid == 0) {
close(pipe_fds[1]);
(void)read(pipe_fds[0], &c, 1);
close(pipe_fds[0]);
_exit(PIDFD_PASS);
}
/*
* Stop the child so we can inspect whether we have
* recycled pid PID_RECYCLE.
*/
close(pipe_fds[0]);
ret = kill(recycled_pid, SIGSTOP);
close(pipe_fds[1]);
if (ret) {
(void)wait_for_pid(recycled_pid);
_exit(PIDFD_ERROR);
}
/*
* We have recycled the pid. Try to signal it. This
* needs to fail since this is a different process than
* the one the pidfd refers to.
*/
if (recycled_pid == PID_RECYCLE) {
ret = sys_pidfd_send_signal(pidfd, SIGCONT,
NULL, 0);
if (ret && errno == ESRCH)
child_ret = PIDFD_XFAIL;
else
child_ret = PIDFD_FAIL;
}
/* let the process move on */
ret = kill(recycled_pid, SIGCONT);
if (ret)
(void)kill(recycled_pid, SIGKILL);
if (wait_for_pid(recycled_pid))
_exit(PIDFD_ERROR);
switch (child_ret) {
case PIDFD_FAIL:
/* fallthrough */
case PIDFD_XFAIL:
_exit(child_ret);
case PIDFD_PASS:
break;
default:
/* not reached */
_exit(PIDFD_ERROR);
}
/*
* If the user set a custom pid_max limit we could be
* in the millions.
* Skip the test in this case.
*/
if (recycled_pid > PIDFD_MAX_DEFAULT)
_exit(PIDFD_SKIP);
}
/* failed to recycle pid */
_exit(PIDFD_SKIP);
}
ret = wait_for_pid(pid1);
switch (ret) {
case PIDFD_FAIL:
ksft_exit_fail_msg(
"%s test: Managed to signal recycled pid %d\n",
test_name, PID_RECYCLE);
case PIDFD_PASS:
ksft_exit_fail_msg("%s test: Failed to recycle pid %d\n",
test_name, PID_RECYCLE);
case PIDFD_SKIP:
ksft_test_result_skip("%s test: Skipping test\n", test_name);
ret = 0;
break;
case PIDFD_XFAIL:
ksft_test_result_pass(
"%s test: Failed to signal recycled pid as expected\n",
test_name);
ret = 0;
break;
default /* PIDFD_ERROR */:
ksft_exit_fail_msg("%s test: Error while running tests\n",
test_name);
}
return ret;
}
static int test_pidfd_send_signal_syscall_support(void)
{
int pidfd, ret;
const char *test_name = "pidfd_send_signal check for support";
pidfd = open("/proc/self", O_DIRECTORY | O_CLOEXEC);
if (pidfd < 0)
ksft_exit_fail_msg(
"%s test: Failed to open process file descriptor\n",
test_name);
ret = sys_pidfd_send_signal(pidfd, 0, NULL, 0);
if (ret < 0) {
if (errno == ENOSYS) {
ksft_test_result_skip(
"%s test: pidfd_send_signal() syscall not supported\n",
test_name);
return 0;
}
ksft_exit_fail_msg("%s test: Failed to send signal\n",
test_name);
}
have_pidfd_send_signal = true;
close(pidfd);
ksft_test_result_pass(
"%s test: pidfd_send_signal() syscall is supported. Tests can be executed\n",
test_name);
return 0;
}
static void *test_pidfd_poll_exec_thread(void *priv)
{
ksft_print_msg("Child Thread: starting. pid %d tid %ld ; and sleeping\n",
getpid(), syscall(SYS_gettid));
ksft_print_msg("Child Thread: doing exec of sleep\n");
execl("/bin/sleep", "sleep", str(CHILD_THREAD_MIN_WAIT), (char *)NULL);
ksft_print_msg("Child Thread: DONE. pid %d tid %ld\n",
getpid(), syscall(SYS_gettid));
return NULL;
}
static void poll_pidfd(const char *test_name, int pidfd)
{
int c;
int epoll_fd = epoll_create1(EPOLL_CLOEXEC);
struct epoll_event event, events[MAX_EVENTS];
if (epoll_fd == -1)
ksft_exit_fail_msg("%s test: Failed to create epoll file descriptor "
"(errno %d)\n",
test_name, errno);
event.events = EPOLLIN;
event.data.fd = pidfd;
if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, pidfd, &event)) {
ksft_exit_fail_msg("%s test: Failed to add epoll file descriptor "
"(errno %d)\n",
test_name, errno);
}
c = epoll_wait(epoll_fd, events, MAX_EVENTS, 5000);
if (c != 1 || !(events[0].events & EPOLLIN))
ksft_exit_fail_msg("%s test: Unexpected epoll_wait result (c=%d, events=%x) "
"(errno %d)\n",
test_name, c, events[0].events, errno);
close(epoll_fd);
return;
}
static int child_poll_exec_test(void *args)
{
pthread_t t1;
ksft_print_msg("Child (pidfd): starting. pid %d tid %ld\n", getpid(),
syscall(SYS_gettid));
pthread_create(&t1, NULL, test_pidfd_poll_exec_thread, NULL);
/*
* Exec in the non-leader thread will destroy the leader immediately.
* If the wait in the parent returns too soon, the test fails.
*/
while (1)
sleep(1);
return 0;
}
static void test_pidfd_poll_exec(int use_waitpid)
{
int pid, pidfd = 0;
int status, ret;
time_t prog_start = time(NULL);
const char *test_name = "pidfd_poll check for premature notification on child thread exec";
ksft_print_msg("Parent: pid: %d\n", getpid());
pid = pidfd_clone(CLONE_PIDFD, &pidfd, child_poll_exec_test);
if (pid < 0)
ksft_exit_fail_msg("%s test: pidfd_clone failed (ret %d, errno %d)\n",
test_name, pid, errno);
ksft_print_msg("Parent: Waiting for Child (%d) to complete.\n", pid);
if (use_waitpid) {
ret = waitpid(pid, &status, 0);
if (ret == -1)
ksft_print_msg("Parent: error\n");
if (ret == pid)
ksft_print_msg("Parent: Child process waited for.\n");
} else {
poll_pidfd(test_name, pidfd);
}
time_t prog_time = time(NULL) - prog_start;
ksft_print_msg("Time waited for child: %lu\n", prog_time);
close(pidfd);
if (prog_time < CHILD_THREAD_MIN_WAIT || prog_time > CHILD_THREAD_MIN_WAIT + 2)
ksft_exit_fail_msg("%s test: Failed\n", test_name);
else
ksft_test_result_pass("%s test: Passed\n", test_name);
}
static void *test_pidfd_poll_leader_exit_thread(void *priv)
{
ksft_print_msg("Child Thread: starting. pid %d tid %ld ; and sleeping\n",
getpid(), syscall(SYS_gettid));
sleep(CHILD_THREAD_MIN_WAIT);
ksft_print_msg("Child Thread: DONE. pid %d tid %ld\n", getpid(), syscall(SYS_gettid));
return NULL;
}
static time_t *child_exit_secs;
static int child_poll_leader_exit_test(void *args)
{
pthread_t t1, t2;
ksft_print_msg("Child: starting. pid %d tid %ld\n", getpid(), syscall(SYS_gettid));
pthread_create(&t1, NULL, test_pidfd_poll_leader_exit_thread, NULL);
pthread_create(&t2, NULL, test_pidfd_poll_leader_exit_thread, NULL);
/*
* glibc exit calls exit_group syscall, so explicity call exit only
* so that only the group leader exits, leaving the threads alone.
*/
*child_exit_secs = time(NULL);
syscall(SYS_exit, 0);
/* Never reached, but appeases compiler thinking we should return. */
exit(0);
}
static void test_pidfd_poll_leader_exit(int use_waitpid)
{
int pid, pidfd = 0;
int status, ret = 0;
const char *test_name = "pidfd_poll check for premature notification on non-empty"
"group leader exit";
child_exit_secs = mmap(NULL, sizeof *child_exit_secs, PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_ANONYMOUS, -1, 0);
if (child_exit_secs == MAP_FAILED)
ksft_exit_fail_msg("%s test: mmap failed (errno %d)\n",
test_name, errno);
ksft_print_msg("Parent: pid: %d\n", getpid());
pid = pidfd_clone(CLONE_PIDFD, &pidfd, child_poll_leader_exit_test);
if (pid < 0)
ksft_exit_fail_msg("%s test: pidfd_clone failed (ret %d, errno %d)\n",
test_name, pid, errno);
ksft_print_msg("Parent: Waiting for Child (%d) to complete.\n", pid);
if (use_waitpid) {
ret = waitpid(pid, &status, 0);
if (ret == -1)
ksft_print_msg("Parent: error\n");
} else {
/*
* This sleep tests for the case where if the child exits, and is in
* EXIT_ZOMBIE, but the thread group leader is non-empty, then the poll
* doesn't prematurely return even though there are active threads
*/
sleep(1);
poll_pidfd(test_name, pidfd);
}
if (ret == pid)
ksft_print_msg("Parent: Child process waited for.\n");
time_t since_child_exit = time(NULL) - *child_exit_secs;
ksft_print_msg("Time since child exit: %lu\n", since_child_exit);
close(pidfd);
if (since_child_exit < CHILD_THREAD_MIN_WAIT ||
since_child_exit > CHILD_THREAD_MIN_WAIT + 2)
ksft_exit_fail_msg("%s test: Failed\n", test_name);
else
ksft_test_result_pass("%s test: Passed\n", test_name);
}
int main(int argc, char **argv)
{
ksft_print_header();
ksft_set_plan(8);
test_pidfd_poll_exec(0);
test_pidfd_poll_exec(1);
test_pidfd_poll_leader_exit(0);
test_pidfd_poll_leader_exit(1);
test_pidfd_send_signal_syscall_support();
test_pidfd_send_signal_simple_success();
test_pidfd_send_signal_exited_fail();
test_pidfd_send_signal_recycled_pid_fail();
ksft_exit_pass();
}
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