/* Copyright (C) 2012-2018 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

   <http://www.gnu.org/licenses/>.  */

/* Verify that tunables correctly filter out unsafe environment variables like

   MALLOC_CHECK_ and MALLOC_MMAP_THRESHOLD_ but also retain

   MALLOC_MMAP_THRESHOLD_ in an unprivileged child.  */

#include <errno.h>

#include <fcntl.h>

#include <stdlib.h>

#include <stdint.h>

#include <stdio.h>

#include <string.h>

#include <sys/stat.h>

#include <sys/wait.h>

#include <unistd.h>

#include <support/support.h>

#include <support/test-driver.h>

static char SETGID_CHILD[] = "setgid-child";

#define CHILD_STATUS 42

/* Return a GID which is not our current GID, but is present in the

   supplementary group list.  */

static gid_t

choose_gid (void)

{

  const int count = 64;

  gid_t groups[count];

  int ret = getgroups (count, groups);

  if (ret < 0)

    {

      printf ("getgroups: %m\n");

      exit (1);

    }

  gid_t current = getgid ();

  for (int i = 0; i < ret; ++i)

    {

      if (groups[i] != current)

	return groups[i];

    }

  return 0;

}

/* Spawn and execute a program and verify that it returns the CHILD_STATUS.  */

static pid_t

do_execve (char **args)

{

  pid_t kid = vfork ();

  if (kid < 0)

    {

      printf ("vfork: %m\n");

      return -1;

    }

  if (kid == 0)

    {

      /* Child process.  */

      execve (args[0], args, environ);

      _exit (-errno);

    }

  if (kid < 0)

    return 1;

  int status;

  if (waitpid (kid, &status, 0) < 0)

    {

      printf ("waitpid: %m\n");

      return 1;

    }

  if (WEXITSTATUS (status) == EXIT_UNSUPPORTED)

    return EXIT_UNSUPPORTED;

  if (!WIFEXITED (status) || WEXITSTATUS (status) != CHILD_STATUS)

    {

      printf ("Unexpected exit status %d from child process\n",

	      WEXITSTATUS (status));

      return 1;

    }

  return 0;

}

/* Copies the executable into a restricted directory, so that we can

   safely make it SGID with the TARGET group ID.  Then runs the

   executable.  */

static int

run_executable_sgid (gid_t target)

{

  char *dirname = xasprintf ("%s/tst-tunables-setuid.%jd",

			     test_dir, (intmax_t) getpid ());

  char *execname = xasprintf ("%s/bin", dirname);

  int infd = -1;

  int outfd = -1;

  int ret = 0;

  if (mkdir (dirname, 0700) < 0)

    {

      printf ("mkdir: %m\n");

      goto err;

    }

  infd = open ("/proc/self/exe", O_RDONLY);

  if (infd < 0)

    {

      printf ("open (/proc/self/exe): %m\n");

      goto err;

    }

  outfd = open (execname, O_WRONLY | O_CREAT | O_EXCL, 0700);

  if (outfd < 0)

    {

      printf ("open (%s): %m\n", execname);

      goto err;

    }

  char buf[4096];

  for (;;)

    {

      ssize_t rdcount = read (infd, buf, sizeof (buf));

      if (rdcount < 0)

	{

	  printf ("read: %m\n");

	  goto err;

	}

      if (rdcount == 0)

	break;

      char *p = buf;

      char *end = buf + rdcount;

      while (p != end)

	{

	  ssize_t wrcount = write (outfd, buf, end - p);

	  if (wrcount == 0)

	    errno = ENOSPC;

	  if (wrcount <= 0)

	    {

	      printf ("write: %m\n");

	      goto err;

	    }

	  p += wrcount;

	}

    }

  if (fchown (outfd, getuid (), target) < 0)

    {

      printf ("fchown (%s): %m\n", execname);

      goto err;

    }

  if (fchmod (outfd, 02750) < 0)

    {

      printf ("fchmod (%s): %m\n", execname);

      goto err;

    }

  if (close (outfd) < 0)

    {

      printf ("close (outfd): %m\n");

      goto err;

    }

  if (close (infd) < 0)

    {

      printf ("close (infd): %m\n");

      goto err;

    }

  char *args[] = {execname, SETGID_CHILD, NULL};

  ret = do_execve (args);

err:

  if (outfd >= 0)

    close (outfd);

  if (infd >= 0)

    close (infd);

  if (execname)

    {

      unlink (execname);

      free (execname);

    }

  if (dirname)

    {

      rmdir (dirname);

      free (dirname);

    }

  return ret;

}

#ifndef test_child

static int

test_child (void)

{

  if (getenv ("MALLOC_CHECK_") != NULL)

    {

      printf ("MALLOC_CHECK_ is still set\n");

      return 1;

    }

  if (getenv ("MALLOC_MMAP_THRESHOLD_") == NULL)

    {

      printf ("MALLOC_MMAP_THRESHOLD_ lost\n");

      return 1;

    }

  if (getenv ("LD_HWCAP_MASK") != NULL)

    {

      printf ("LD_HWCAP_MASK still set\n");

      return 1;

    }

  return 0;

}

#endif

#ifndef test_parent

static int

test_parent (void)

{

  if (getenv ("MALLOC_CHECK_") == NULL)

    {

      printf ("MALLOC_CHECK_ lost\n");

      return 1;

    }

  if (getenv ("MALLOC_MMAP_THRESHOLD_") == NULL)

    {

      printf ("MALLOC_MMAP_THRESHOLD_ lost\n");

      return 1;

    }

  if (getenv ("LD_HWCAP_MASK") == NULL)

    {

      printf ("LD_HWCAP_MASK lost\n");

      return 1;

    }

  return 0;

}

#endif

static int

do_test (int argc, char **argv)

{

  /* Setgid child process.  */

  if (argc == 2 && strcmp (argv[1], SETGID_CHILD) == 0)

    {

      if (getgid () == getegid ())

	{

	  /* This can happen if the file system is mounted nosuid.  */

	  fprintf (stderr, "SGID failed: GID and EGID match (%jd)\n",

		   (intmax_t) getgid ());

	  exit (EXIT_UNSUPPORTED);

	}

      int ret = test_child ();

      if (ret != 0)

	exit (1);

      exit (CHILD_STATUS);

    }

  else

    {

      if (test_parent () != 0)

	exit (1);

      /* Try running a setgid program.  */

      gid_t target = choose_gid ();

      if (target == 0)

	{

	  fprintf (stderr,

		   "Could not find a suitable GID for user %jd, skipping test\n",

		   (intmax_t) getuid ());

	  exit (0);

	}

      return run_executable_sgid (target);

    }

  /* Something went wrong and our argv was corrupted.  */

  _exit (1);

}

#define TEST_FUNCTION_ARGV do_test

#include <support/test-driver.c>