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			125 lines
		
	
	
		
			3.7 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			125 lines
		
	
	
		
			3.7 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
/* Specific tests for Linux pidfd_getpid.
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   Copyright (C) 2023-2025 Free Software Foundation, Inc.
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   This file is part of the GNU C Library.
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   The GNU C Library is free software; you can redistribute it and/or
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   modify it under the terms of the GNU Lesser General Public
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   License as published by the Free Software Foundation; either
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   version 2.1 of the License, or (at your option) any later version.
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   The GNU C Library is distributed in the hope that it will be useful,
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   but WITHOUT ANY WARRANTY; without even the implied warranty of
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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   Lesser General Public License for more details.
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   You should have received a copy of the GNU Lesser General Public
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   License along with the GNU C Library; if not, see
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   <https://www.gnu.org/licenses/>.  */
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#include <errno.h>
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#include <sched.h>
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#include <stdlib.h>
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#include <support/check.h>
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#include <support/xunistd.h>
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#include <support/test-driver.h>
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#include <sys/pidfd.h>
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#include <sys/wait.h>
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#include <sys/mount.h>
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static int
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do_test (void)
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{
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  {
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    /* The pidfd_getfd syscall was the last in the set of pidfd related
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       syscalls added to the kernel.  Use pidfd_getfd to decide if this
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       kernel has pidfd support that we can test.  */
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    int r = pidfd_getfd (0, 0, 1);
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    TEST_VERIFY_EXIT (r == -1);
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    if (errno == ENOSYS)
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      FAIL_UNSUPPORTED ("kernel does not support pidfd_getfd, skipping test");
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    if (errno == EPERM)
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      FAIL_UNSUPPORTED ("kernel does not allow pidfd_getfd, skipping test");
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  }
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  /* Check if pidfd_getpid returns EREMOTE for process not in current
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     namespace.  */
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  {
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    pid_t child0 = xfork ();
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    TEST_VERIFY_EXIT (child0 >= 0);
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    if (child0 == 0)
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      {
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	/* Create another unrelated descriptor, so child2 will inherit the
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	   file descriptor.  */
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	pid_t child1 = xfork ();
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	TEST_VERIFY_EXIT (child1 >= 0);
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        if (child1 == 0)
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	  _exit (0);
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	int child1_pidfd = pidfd_open (child1, 0);
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	TEST_VERIFY_EXIT (child1_pidfd != -1);
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	if (unshare (CLONE_NEWNS | CLONE_NEWUSER | CLONE_NEWPID) < 0)
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	  {
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	    /* Older kernels may not support all the options, or security
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	       policy may block this call.  */
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	    if (errno == EINVAL || errno == EPERM
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	        || errno == ENOSPC || errno == EACCES)
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	      exit (EXIT_UNSUPPORTED);
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	    FAIL_EXIT1 ("unshare user/fs/pid failed: %m");
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	  }
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	if (mount (NULL, "/", NULL, MS_REC | MS_PRIVATE, 0) != 0)
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	  {
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	    /* This happens if we're trying to create a nested container,
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	       like if the build is running under podman, and we lack
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	       priviledges.  */
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	    if (errno  == EPERM)
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	      _exit (EXIT_UNSUPPORTED);
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	    else
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	      _exit (EXIT_FAILURE);
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	  }
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	pid_t child2 = xfork ();
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	if (child2 > 0)
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	  {
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	    int status;
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	    xwaitpid (child2, &status, 0);
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	    TEST_VERIFY (WIFEXITED (status));
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	    xwaitpid (child1, &status, 0);
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	    TEST_VERIFY (WIFEXITED (status));
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	    _exit (WEXITSTATUS (status));
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	  }
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	/* Now that we're pid 1 (effectively "root") we can mount /proc  */
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	if (mount ("proc", "/proc", "proc", 0, NULL) != 0)
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	  {
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	    if (errno == EPERM)
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	      _exit (EXIT_UNSUPPORTED);
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	    else
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	      _exit (EXIT_FAILURE);
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	  }
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	TEST_COMPARE (pidfd_getpid (child1_pidfd), -1);
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	TEST_COMPARE (errno, EREMOTE);
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	_exit (EXIT_SUCCESS);
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      }
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      int child0_pidfd = pidfd_open (child0, 0);
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      TEST_VERIFY_EXIT (child0_pidfd != -1);
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      pid_t child0pid = pidfd_getpid (child0_pidfd);
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      siginfo_t info;
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      TEST_COMPARE (waitid (P_PIDFD, child0_pidfd, &info, WEXITED), 0);
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      if (info.si_status == EXIT_UNSUPPORTED)
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	FAIL_UNSUPPORTED ("unable to unshare user/fs/pid");
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      TEST_COMPARE (info.si_status, 0);
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      TEST_COMPARE (info.si_code, CLD_EXITED);
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      TEST_COMPARE (info.si_pid, child0pid);
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  }
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  return 0;
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}
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#include <support/test-driver.c>
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