Re: [PATCH v2 05/15] linux: Add tst-pidfd.c

[Carlos O'Donell <carlos@redhat.com>]

On 2/7/22 12:44, Adhemerval Zanella via Libc-alpha wrote:
> To check for the pidfd functions pidfd_open, pidfd_getfd, pid_send_signal,
> and waitid with P_PIDFD.

OK with suggested text changes in the test.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
 
> Checked on x86_64-linux-gnu and i686-linux-gnu.
> ---
>  sysdeps/unix/sysv/linux/Makefile    |   1 +
>  sysdeps/unix/sysv/linux/tst-pidfd.c | 170 ++++++++++++++++++++++++++++
>  2 files changed, 171 insertions(+)
>  create mode 100644 sysdeps/unix/sysv/linux/tst-pidfd.c
> 
> diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
> index 1c08f0918f..6fefcd8fe7 100644
> --- a/sysdeps/unix/sysv/linux/Makefile
> +++ b/sysdeps/unix/sysv/linux/Makefile
> @@ -127,6 +127,7 @@ tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
>    tst-prctl \
>    tst-scm_rights \
>    tst-epoll \
> +  tst-pidfd \

OK. New linux-specific test.

>    # tests
>  
>  # Test for the symbol version of fcntl that was replaced in glibc 2.28.
> diff --git a/sysdeps/unix/sysv/linux/tst-pidfd.c b/sysdeps/unix/sysv/linux/tst-pidfd.c
> new file mode 100644
> index 0000000000..267b071af4
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-pidfd.c
> @@ -0,0 +1,170 @@
> +/* Basic tests for Linux pidfd interfaces.
> +   Copyright (C) 2022 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 <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>
> +
> +#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;

OK. Globals for parent.

> +
> +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);
> +  }

OK.

> +
> +  /* 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);
> +  }

OK.

> +
> +  /* 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);

OK.

> +
> +  /* Wait for final pidfd_send_signal.  */
> +  pause ();
> +
> +  _exit (0);
> +}
> +
> +static int
> +do_test (void)
> +{
> +  {
> +    /* The pidfd_getfd was the last one added on Linux.  */

Suggest:

/* 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_open, skipping test");

Lets be accurate about what we tested and what we say we tested:
s/pidfd_open/pidfd_getfd/g

> +  }
> +
> +  ppid = getpid ();
> +  puid = getuid ();
> +
> +  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);
> +
> +  /* 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);
> +    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);

OK.

> +  }
> +
> +  TEST_COMPARE (pidfd_send_signal (pidfd, SIGKILL, NULL, 0), 0);

OK. Sends signal.

> +  {
> +    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>

OK.

-- 
Cheers,
Carlos.