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,struct pt_regs *regs)
  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             (bprm->recursion_depth > BINPRM_MAX_RECURSION))
  27                 return -ENOEXEC;
  28         /*
  29          * This section does the #! interpretation.
  30          * Sorta complicated, but hopefully it will work.  -TYT
  31          */
  32
  33         bprm->recursion_depth++;
  34         allow_write_access(bprm->file);
  35         fput(bprm->file);
  36         bprm->file = NULL;
  37
  38         bprm->buf[BINPRM_BUF_SIZE - 1] = '\0';
  39         if ((cp = strchr(bprm->buf, '\n')) == NULL)
  40                 cp = bprm->buf+BINPRM_BUF_SIZE-1;
  41         *cp = '\0';
  42         while (cp > bprm->buf) {
  43                 cp--;
  44                 if ((*cp == ' ') || (*cp == '\t'))
  45                         *cp = '\0';
  46                 else
  47                         break;
  48         }
  49         for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++);
  50         if (*cp == '\0')
  51                 return -ENOEXEC; /* No interpreter name found */
  52         i_name = cp;
  53         i_arg = NULL;
  54         for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++)
  55                 /* nothing */ ;
  56         while ((*cp == ' ') || (*cp == '\t'))
  57                 *cp++ = '\0';
  58         if (*cp)
  59                 i_arg = cp;
  60         strcpy (interp, i_name);
  61         /*
  62          * OK, we've parsed out the interpreter name and
  63          * (optional) argument.
  64          * Splice in (1) the interpreter's name for argv[0]
  65          *           (2) (optional) argument to interpreter
  66          *           (3) filename of shell script (replace argv[0])
  67          *
  68          * This is done in reverse order, because of how the
  69          * user environment and arguments are stored.
  70          */
  71         retval = remove_arg_zero(bprm);
  72         if (retval)
  73                 return retval;
  74         retval = copy_strings_kernel(1, &bprm->interp, bprm);
  75         if (retval < 0) return retval;
  76         bprm->argc++;
  77         if (i_arg) {
  78                 retval = copy_strings_kernel(1, &i_arg, bprm);
  79                 if (retval < 0) return retval;
  80                 bprm->argc++;
  81         }
  82         retval = copy_strings_kernel(1, &i_name, bprm);
  83         if (retval) return retval;
  84         bprm->argc++;
  85         bprm->interp = interp;
  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,regs);
  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         return register_binfmt(&script_format);
 109 }
 110
 111 static void __exit exit_script_binfmt(void)
 112 {
 113         unregister_binfmt(&script_format);
 114 }
 115
 116 core_initcall(init_script_binfmt);
 117 module_exit(exit_script_binfmt);
 118 MODULE_LICENSE("GPL");