/* 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/>.  */

/* Test that secure_getenv works by invoking the test as a SGID

   program with a group ID from the supplementary group list.  This

   test can fail spuriously if the user is not a member of a suitable

   supplementary group.  */

#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 MAGIC_ARGUMENT[] = "run-actual-test";

#define MAGIC_STATUS 19

/* 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;

}

/* 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/secure-getenv.%jd",

			     test_dir, (intmax_t) getpid ());

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

  int infd = -1;

  int outfd = -1;

  int ret = -1;

  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;

    }

  int kid = fork ();

  if (kid < 0)

    {

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

      goto err;

    }

  if (kid == 0)

    {

      /* Child process.  */

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

      execve (execname, args, environ);

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

      _exit (1);

    }

  int status;

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

    {

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

      goto err;

    }

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

    {

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

	      status);

      goto err;

    }

  ret = 0;

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;

}

static int

do_test (void)

{

  if (getenv ("PATH") == NULL)

    {

      printf ("PATH not set\n");

      exit (1);

    }

  if (secure_getenv ("PATH") == NULL)

    {

      printf ("PATH not set according to secure_getenv\n");

      exit (1);

    }

  if (strcmp (getenv ("PATH"), secure_getenv ("PATH")) != 0)

    {

      printf ("PATH mismatch (%s, %s)\n",

	      getenv ("PATH"), secure_getenv ("PATH"));

      exit (1);

    }

  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);

}

static void

alternative_main (int argc, char **argv)

{

  if (argc == 2 && strcmp (argv[1], MAGIC_ARGUMENT) == 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 (MAGIC_STATUS);

	}

      if (getenv ("PATH") == NULL)

	{

	  printf ("PATH variable not present\n");

	  exit (3);

	}

      if (secure_getenv ("PATH") != NULL)

	{

	  printf ("PATH variable not filtered out\n");

	  exit (4);

	}

      exit (MAGIC_STATUS);

    }

}

#define PREPARE alternative_main

#include <support/test-driver.c>