fs/binfmt_script.c

   1 /*
   2  *  linux/fs/binfmt_script.c
   3  *
   4  *  Copyright (C) 1996  Martin von Löwis
   5  *  original #!-checking implemented by tytso.
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/string.h>
  10 #include <linux/stat.h>
  11 #include <linux/binfmts.h>
  12 #include <linux/init.h>
  13 #include <linux/file.h>
  14 #include <linux/err.h>
  15 #include <linux/fs.h>
  16
  17 static int load_script(struct linux_binprm *bprm)
  18 {
  19         const char *i_arg, *i_name;
  20         char *cp;
  21         struct file *file;
  22         char interp[BINPRM_BUF_SIZE];
  23         int retval;
  24
  25         if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!'))
  26                 return -ENOEXEC;
  27         /*
  28          * This section does the #! interpretation.
  29          * Sorta complicated, but hopefully it will work.  -TYT
  30          */
  31
  32         allow_write_access(bprm->file);
  33         fput(bprm->file);
  34         bprm->file = NULL;
  35
  36         bprm->buf[BINPRM_BUF_SIZE - 1] = '\0';
  37         if ((cp = strchr(bprm->buf, '\n')) == NULL)
  38                 cp = bprm->buf+BINPRM_BUF_SIZE-1;
  39         *cp = '\0';
  40         while (cp > bprm->buf) {
  41                 cp--;
  42                 if ((*cp == ' ') || (*cp == '\t'))
  43                         *cp = '\0';
  44                 else
  45                         break;
  46         }
  47         for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++);
  48         if (*cp == '\0')
  49                 return -ENOEXEC; /* No interpreter name found */
  50         i_name = cp;
  51         i_arg = NULL;
  52         for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++)
  53                 /* nothing */ ;
  54         while ((*cp == ' ') || (*cp == '\t'))
  55                 *cp++ = '\0';
  56         if (*cp)
  57                 i_arg = cp;
  58         strcpy (interp, i_name);
  59         /*
  60          * OK, we've parsed out the interpreter name and
  61          * (optional) argument.
  62          * Splice in (1) the interpreter's name for argv[0]
  63          *           (2) (optional) argument to interpreter
  64          *           (3) filename of shell script (replace argv[0])
  65          *
  66          * This is done in reverse order, because of how the
  67          * user environment and arguments are stored.
  68          */
  69         retval = remove_arg_zero(bprm);
  70         if (retval)
  71                 return retval;
  72         retval = copy_strings_kernel(1, &bprm->interp, bprm);
  73         if (retval < 0) return retval;
  74         bprm->argc++;
  75         if (i_arg) {
  76                 retval = copy_strings_kernel(1, &i_arg, bprm);
  77                 if (retval < 0) return retval;
  78                 bprm->argc++;
  79         }
  80         retval = copy_strings_kernel(1, &i_name, bprm);
  81         if (retval) return retval;
  82         bprm->argc++;
  83         retval = bprm_change_interp(interp, bprm);
  84         if (retval < 0)
  85                 return retval;
  86
  87         /*
  88          * OK, now restart the process with the interpreter's dentry.
  89          */
  90         file = open_exec(interp);
  91         if (IS_ERR(file))
  92                 return PTR_ERR(file);
  93
  94         bprm->file = file;
  95         retval = prepare_binprm(bprm);
  96         if (retval < 0)
  97                 return retval;
  98         return search_binary_handler(bprm);
  99 }
 100
 101 static struct linux_binfmt script_format = {
 102         .module         = THIS_MODULE,
 103         .load_binary    = load_script,
 104 };
 105
 106 static int __init init_script_binfmt(void)
 107 {
 108         register_binfmt(&script_format);
 109         return 0;
 110 }
 111
 112 static void __exit exit_script_binfmt(void)
 113 {
 114         unregister_binfmt(&script_format);
 115 }
 116
 117 core_initcall(init_script_binfmt);
 118 module_exit(exit_script_binfmt);
 119 MODULE_LICENSE("GPL");