tst-env-setuid: Use support_capture_subprogram_self_sgid

Use the support_capture_subprogram_self_sgid to spawn an sgid child.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

(cherry picked from commit ca335281068a1ed549a75ee64f90a8310755956f)

diff --git a/elf/tst-env-setuid.c b/elf/tst-env-setuid.c

index 183a6dd133cfa16e..eda87f9dda293e79 100644

--- a/elf/tst-env-setuid.c

+++ b/elf/tst-env-setuid.c

@@ -29,173 +29,12 @@

 #include <sys/wait.h>

 #include <unistd.h>

+#include <support/check.h>

 #include <support/support.h>

 #include <support/test-driver.h>

+#include <support/capture_subprocess.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

@@ -256,40 +95,32 @@ do_test (int argc, char **argv)

   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);

-	}

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

+	FAIL_UNSUPPORTED ("SGID failed: GID and EGID match (%jd)\n",

+			  (intmax_t) getgid ());

       int ret = test_child ();

       if (ret != 0)

 	exit (1);

-      exit (CHILD_STATUS);

+      exit (EXIT_SUCCESS);

     }

   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);

-	}

+      int status = support_capture_subprogram_self_sgid (SETGID_CHILD);

-      return run_executable_sgid (target);

-    }

+      if (WEXITSTATUS (status) == EXIT_UNSUPPORTED)

+	return EXIT_UNSUPPORTED;

+

+      if (!WIFEXITED (status))

+	FAIL_EXIT1 ("Unexpected exit status %d from child process\n", status);

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

-  _exit (1);

+      return 0;

+    }

 }

 #define TEST_FUNCTION_ARGV do_test