/*

 * Sandbox helper for CUPS.

 *

 * Copyright 2007-2014 by Apple Inc.

 *

 * These coded instructions, statements, and computer programs are the

 * property of Apple Inc. and are protected by Federal copyright

 * law.  Distribution and use rights are outlined in the file "LICENSE.txt"

 * which should have been included with this file.  If this file is

 * missing or damaged, see the license at "http://www.cups.org/".

 *

 * Usage:

 *

 *     cups-exec /path/to/profile [-u UID] [-g GID] [-n NICE] /path/to/program argv0 argv1 ... argvN

 */

/*

 * Include necessary headers...

 */

#include <cups/string-private.h>

#include <cups/file.h>

#include <unistd.h>

#include <fcntl.h>

#include <grp.h>

#include <sys/stat.h>

#ifdef HAVE_SANDBOX_H

#  include <sandbox.h>

#  ifndef SANDBOX_NAMED_EXTERNAL

#    define SANDBOX_NAMED_EXTERNAL  0x0003

#  endif /* !SANDBOX_NAMED_EXTERNAL */

#  pragma GCC diagnostic ignored "-Wdeprecated-declarations"

#endif /* HAVE_SANDBOX_H */

/*

 * Local functions...

 */

static void	usage(void) __attribute__((noreturn));

/*

 * 'main()' - Apply sandbox profile and execute program.

 */

int					/* O - Exit status */

main(int  argc,				/* I - Number of command-line args */

     char *argv[])			/* I - Command-line arguments */

{

  int		i;			/* Looping var */

  const char	*opt;			/* Current option character */

  uid_t		uid = getuid();		/* UID */

  gid_t		gid = getgid();		/* GID */

  int		niceval = 0;		/* Nice value */

#ifdef HAVE_SANDBOX_H

  char		*sandbox_error = NULL;	/* Sandbox error, if any */

#endif /* HAVE_SANDBOX_H */

 /*

  * Parse command-line...

  */

  for (i = 1; i < argc; i ++)

  {

    if (argv[i][0] == '-')

    {

      for (opt = argv[i] + 1; *opt; opt ++)

      {

        switch (*opt)

        {

          case 'g' : /* -g gid */

              i ++;

              if (i >= argc)

                usage();

              gid = (gid_t)atoi(argv[i]);

              break;

          case 'n' : /* -n nice-value */

              i ++;

              if (i >= argc)

                usage();

              niceval = atoi(argv[i]);

              break;

          case 'u' : /* -g gid */

              i ++;

              if (i >= argc)

                usage();

              uid = (uid_t)atoi(argv[i]);

              break;

	  default :

	      fprintf(stderr, "cups-exec: Unknown option '-%c'.\n", *opt);

	      usage();

        }

      }

    }

    else

      break;

  }

 /*

  * Check that we have enough arguments...

  */

  if ((i + 3) > argc)

  {

    fputs("cups-exec: Insufficient arguments.\n", stderr);

    usage();

  }

 /*

  * Make sure side and back channel FDs are non-blocking...

  */

  fcntl(3, F_SETFL, O_NDELAY);

  fcntl(4, F_SETFL, O_NDELAY);

 /*

  * Change UID, GID, and nice value...

  */

  if (uid)

    nice(niceval);

  if (!getuid())

  {

    if (setgid(gid))

      exit(errno + 100);

    if (setgroups(1, &gid))

      exit(errno + 100);

    if (uid && setuid(uid))

      exit(errno + 100);

  }

  umask(077);

#ifdef HAVE_SANDBOX_H

 /*

  * Run in a separate security profile...

  */

  if (strcmp(argv[i], "none") &&

      sandbox_init(argv[i], SANDBOX_NAMED_EXTERNAL, &sandbox_error))

  {

    cups_file_t	*fp;			/* File */

    char	line[1024];		/* Line from file */

    int		linenum = 0;		/* Line number in file */

    fprintf(stderr, "DEBUG: sandbox_init failed: %s (%s)\n", sandbox_error,

	    strerror(errno));

    sandbox_free_error(sandbox_error);

    if ((fp = cupsFileOpen(argv[i], "r")) != NULL)

    {

      while (cupsFileGets(fp, line, sizeof(line)))

      {

        linenum ++;

        fprintf(stderr, "DEBUG: %4d  %s\n", linenum, line);

      }

      cupsFileClose(fp);

    }

    return (100 + EINVAL);

  }

#endif /* HAVE_SANDBOX_H */

 /*

  * Execute the program...

  */

  execv(argv[i + 1], argv + i + 2);

 /*

  * If we get here, execv() failed...

  */

  fprintf(stderr, "DEBUG: execv failed: %s\n", strerror(errno));

  return (errno + 100);

}

/*

 * 'usage()' - Show program usage.

 */

static void

usage(void)

{

  fputs("Usage: cups-exec [-g gid] [-n nice-value] [-u uid] /path/to/profile /path/to/program argv0 argv1 ... argvN\n", stderr);

  exit(1);

}