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/* Basic tests for Linux pidfd interfaces.
Copyright (C) 2022-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <support/capture_subprocess.h>
#include <support/check.h>
#include <support/process_state.h>
#include <support/support.h>
#include <support/xsignal.h>
#include <support/xunistd.h>
#include <support/xsocket.h>
#include <sys/pidfd.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <unistd.h>
#define REMOTE_PATH "/dev/null"
/* The pair of sockets used for coordination. The subprocess uses
sockets[1]. */
static int sockets[2];
static pid_t ppid;
static uid_t puid;
static void
sighandler (int sig)
{
}
static void
subprocess (void)
{
xsignal (SIGUSR1, sighandler);
xsignal (SIGUSR2, sighandler);
/* Check first pidfd_send_signal with default NULL siginfo_t argument. */
{
sigset_t set;
sigemptyset (&set);
sigaddset (&set, SIGUSR1);
siginfo_t info;
TEST_COMPARE (sigtimedwait (&set, &info, NULL), SIGUSR1);
TEST_COMPARE (info.si_signo, SIGUSR1);
TEST_COMPARE (info.si_errno, 0);
TEST_COMPARE (info.si_code, SI_USER);
TEST_COMPARE (info.si_pid, ppid);
TEST_COMPARE (info.si_uid, puid);
}
/* Check second pidfd_send_signal with crafted siginfo_t argument. */
{
sigset_t set;
sigemptyset (&set);
sigaddset (&set, SIGUSR2);
siginfo_t info;
TEST_COMPARE (sigtimedwait (&set, &info, NULL), SIGUSR2);
TEST_COMPARE (info.si_signo, SIGUSR2);
TEST_COMPARE (info.si_errno, EAGAIN);
TEST_COMPARE (info.si_code, -10);
TEST_COMPARE (info.si_pid, ppid);
TEST_COMPARE (info.si_uid, puid);
}
/* Send a local file descriptor value to check pidfd_getfd. */
int remote_fd = xopen (REMOTE_PATH, O_WRONLY | O_CLOEXEC, 0);
xsendto (sockets[1], &remote_fd, sizeof (remote_fd), 0, NULL, 0);
/* Wait for final pidfd_send_signal. */
pause ();
_exit (0);
}
static int
do_test (void)
{
{
/* The pidfd_getfd syscall was the last in the set of pidfd related
syscalls added to the kernel. Use pidfd_getfd to decide if this
kernel has pidfd support that we can test. */
int r = pidfd_getfd (0, 0, 1);
TEST_VERIFY_EXIT (r == -1);
if (errno == ENOSYS)
FAIL_UNSUPPORTED ("kernel does not support pidfd_getfd, skipping test");
}
ppid = getpid ();
puid = getuid ();
/* Sanity check for invalid inputs. */
TEST_COMPARE (pidfd_getpid (-1), -1);
TEST_COMPARE (errno, EBADF);
{
pid_t pid = pidfd_getpid (STDOUT_FILENO);
TEST_COMPARE (pid, -1);
TEST_COMPARE (errno, EBADF);
}
/* Check if pidfd_getpid returns ESRCH for exited subprocess. */
{
pid_t pidfork = xfork ();
if (pidfork == 0)
_exit (EXIT_SUCCESS);
int pidfork_pidfd = pidfd_open (pidfork, 0);
/* The process might be still running or already in zombie state, in
either case the PID is still allocated to the process. */
pid_t pid = pidfd_getpid (pidfork_pidfd);
TEST_COMPARE (pidfork, pid);
if (pid > 0)
support_process_state_wait (pid, support_process_state_zombie);
siginfo_t info;
TEST_COMPARE (waitid (P_PIDFD, pidfork_pidfd, &info, WEXITED), 0);
TEST_COMPARE (info.si_pid, pidfork);
TEST_COMPARE (info.si_status, 0);
TEST_COMPARE (info.si_code, CLD_EXITED);
/* Once the process is reaped the associated PID is not available. */
pid = pidfd_getpid (pidfork_pidfd);
TEST_COMPARE (pid, -1);
TEST_COMPARE (errno, ESRCH);
xclose (pidfork_pidfd);
}
TEST_COMPARE (socketpair (AF_UNIX, SOCK_STREAM, 0, sockets), 0);
pid_t pid = xfork ();
if (pid == 0)
{
xclose (sockets[0]);
subprocess ();
}
xclose (sockets[1]);
TEST_COMPARE (pidfd_open (-1, 0), -1);
TEST_COMPARE (errno, EINVAL);
int pidfd = pidfd_open (pid, 0);
TEST_VERIFY (pidfd != -1);
TEST_COMPARE (pidfd_getpid (INT_MAX), -1);
{
pid_t querypid = pidfd_getpid (pidfd);
TEST_COMPARE (querypid, pid);
}
/* Wait for first sigtimedwait. */
support_process_state_wait (pid, support_process_state_sleeping);
TEST_COMPARE (pidfd_send_signal (pidfd, SIGUSR1, NULL, 0), 0);
/* Wait for second sigtimedwait. */
support_process_state_wait (pid, support_process_state_sleeping);
{
siginfo_t info =
{
.si_signo = SIGUSR2,
.si_errno = EAGAIN,
.si_code = -10,
.si_pid = ppid,
.si_uid = puid
};
TEST_COMPARE (pidfd_send_signal (pidfd, SIGUSR2, &info, 0), 0);
}
/* Get remote file descriptor to check for pidfd_getfd. */
{
int remote_fd;
xrecvfrom (sockets[0], &remote_fd, sizeof (remote_fd), 0, NULL, 0);
int fd = pidfd_getfd (pidfd, remote_fd, 0);
/* pidfd_getfd may fail with EPERM if the process does not have
PTRACE_MODE_ATTACH_REALCREDS permissions. This means the call
may be denied if the process doesn't have CAP_SYS_PTRACE or
if a LSM security_ptrace_access_check denies access. */
if (fd == -1 && errno == EPERM)
{
TEST_COMPARE (pidfd_send_signal (pidfd, SIGKILL, NULL, 0), 0);
FAIL_UNSUPPORTED ("don't have permission to use pidfd_getfd on pidfd, "
"skipping test");
}
TEST_VERIFY (fd > 0);
char *path = xasprintf ("/proc/%d/fd/%d", pid, remote_fd);
char *resolved = xreadlink (path);
TEST_COMPARE_STRING (resolved, REMOTE_PATH);
int remote_fd_mode = fcntl (fd, F_GETFL);
TEST_VERIFY (remote_fd_mode != -1);
TEST_VERIFY (remote_fd_mode & O_WRONLY);
int remote_fd_flags = fcntl (fd, F_GETFD);
TEST_VERIFY (remote_fd_flags != -1);
TEST_VERIFY (remote_fd_flags & FD_CLOEXEC);
}
TEST_COMPARE (pidfd_send_signal (pidfd, SIGKILL, NULL, 0), 0);
{
siginfo_t info;
int r = waitid (P_PIDFD, pidfd, &info, WEXITED);
TEST_COMPARE (r, 0);
TEST_COMPARE (info.si_status, SIGKILL);
TEST_COMPARE (info.si_code, CLD_KILLED);
}
return 0;
}
#include <support/test-driver.c>
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