scheduler/cups-exec.c

   1 /*
   2  * Sandbox helper for CUPS.
   3  *
   4  * Copyright 2007-2014 by Apple Inc.
   5  *
   6  * These coded instructions, statements, and computer programs are the
   7  * property of Apple Inc. and are protected by Federal copyright
   8  * law.  Distribution and use rights are outlined in the file "LICENSE.txt"
   9  * which should have been included with this file.  If this file is
  10  * file is missing or damaged, see the license at "http://www.cups.org/".
  11  *
  12  * Usage:
  13  *
  14  *     cups-exec /path/to/profile [-u UID] [-g GID] [-n NICE] /path/to/program argv0 argv1 ... argvN
  15  */
  16
  17 /*
  18  * Include necessary headers...
  19  */
  20
  21 #include <cups/string-private.h>
  22 #include <cups/file.h>
  23 #include <unistd.h>
  24 #include <fcntl.h>
  25 #include <grp.h>
  26 #include <sys/stat.h>
  27 #ifdef HAVE_SANDBOX_H
  28 #  include <sandbox.h>
  29 #  ifndef SANDBOX_NAMED_EXTERNAL
  30 #    define SANDBOX_NAMED_EXTERNAL  0x0003
  31 #  endif /* !SANDBOX_NAMED_EXTERNAL */
  32 #  pragma GCC diagnostic ignored "-Wdeprecated-declarations"
  33 #endif /* HAVE_SANDBOX_H */
  34
  35
  36 /*
  37  * Local functions...
  38  */
  39
  40 static void     usage(void) __attribute__((noreturn));
  41
  42
  43 /*
  44  * 'main()' - Apply sandbox profile and execute program.
  45  */
  46
  47 int                                     /* O - Exit status */
  48 main(int  argc,                         /* I - Number of command-line args */
  49      char *argv[])                      /* I - Command-line arguments */
  50 {
  51   int           i;                      /* Looping var */
  52   const char    *opt;                   /* Current option character */
  53   uid_t         uid = getuid();         /* UID */
  54   gid_t         gid = getgid();         /* GID */
  55   int           niceval = 0;            /* Nice value */
  56 #ifdef HAVE_SANDBOX_H
  57   char          *sandbox_error = NULL;  /* Sandbox error, if any */
  58 #endif /* HAVE_SANDBOX_H */
  59
  60
  61  /*
  62   * Parse command-line...
  63   */
  64
  65   for (i = 1; i < argc; i ++)
  66   {
  67     if (argv[i][0] == '-')
  68     {
  69       for (opt = argv[i] + 1; *opt; opt ++)
  70       {
  71         switch (*opt)
  72         {
  73           case 'g' : /* -g gid */
  74               i ++;
  75               if (i >= argc)
  76                 usage();
  77
  78               gid = (gid_t)atoi(argv[i]);
  79               break;
  80
  81           case 'n' : /* -n nice-value */
  82               i ++;
  83               if (i >= argc)
  84                 usage();
  85
  86               niceval = atoi(argv[i]);
  87               break;
  88
  89           case 'u' : /* -g gid */
  90               i ++;
  91               if (i >= argc)
  92                 usage();
  93
  94               uid = (uid_t)atoi(argv[i]);
  95               break;
  96
  97           default :
  98               fprintf(stderr, "cups-exec: Unknown option '-%c'.\n", *opt);
  99               usage();
 100         }
 101       }
 102     }
 103     else
 104       break;
 105   }
 106
 107  /*
 108   * Check that we have enough arguments...
 109   */
 110
 111   if ((i + 3) > argc)
 112   {
 113     fputs("cups-exec: Insufficient arguments.\n", stderr);
 114     usage();
 115   }
 116
 117  /*
 118   * Make sure side and back channel FDs are non-blocking...
 119   */
 120
 121   fcntl(3, F_SETFL, O_NDELAY);
 122   fcntl(4, F_SETFL, O_NDELAY);
 123
 124  /*
 125   * Change UID, GID, and nice value...
 126   */
 127
 128   if (uid)
 129     nice(niceval);
 130
 131   if (!getuid())
 132   {
 133     if (setgid(gid))
 134       exit(errno + 100);
 135
 136     if (setgroups(1, &gid))
 137       exit(errno + 100);
 138
 139     if (uid && setuid(uid))
 140       exit(errno + 100);
 141   }
 142
 143   umask(077);
 144
 145 #ifdef HAVE_SANDBOX_H
 146  /*
 147   * Run in a separate security profile...
 148   */
 149
 150   if (strcmp(argv[i], "none") &&
 151       sandbox_init(argv[i], SANDBOX_NAMED_EXTERNAL, &sandbox_error))
 152   {
 153     cups_file_t *fp;                    /* File */
 154     char        line[1024];             /* Line from file */
 155     int         linenum = 0;            /* Line number in file */
 156
 157     fprintf(stderr, "DEBUG: sandbox_init failed: %s (%s)\n", sandbox_error,
 158             strerror(errno));
 159     sandbox_free_error(sandbox_error);
 160
 161     if ((fp = cupsFileOpen(argv[i], "r")) != NULL)
 162     {
 163       while (cupsFileGets(fp, line, sizeof(line)))
 164       {
 165         linenum ++;
 166         fprintf(stderr, "DEBUG: %4d  %s\n", linenum, line);
 167       }
 168       cupsFileClose(fp);
 169     }
 170
 171     return (100 + EINVAL);
 172   }
 173 #endif /* HAVE_SANDBOX_H */
 174
 175  /*
 176   * Execute the program...
 177   */
 178
 179   execv(argv[i + 1], argv + i + 2);
 180
 181  /*
 182   * If we get here, execv() failed...
 183   */
 184
 185   fprintf(stderr, "DEBUG: execv failed: %s\n", strerror(errno));
 186   return (errno + 100);
 187 }
 188
 189
 190 /*
 191  * 'usage()' - Show program usage.
 192  */
 193
 194 static void
 195 usage(void)
 196 {
 197   fputs("Usage: cups-exec [-g gid] [-n nice-value] [-u uid] /path/to/profile /path/to/program argv0 argv1 ... argvN\n", stderr);
 198   exit(1);
 199 }