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/malloc.h>
  12 #include <linux/binfmts.h>
  13 #include <linux/init.h>
  14 #include <linux/file.h>
  15 #include <linux/smp_lock.h>
  16
  17 static int load_script(struct linux_binprm *bprm,struct pt_regs *regs)
  18 {
  19         char *cp, *i_name, *i_arg;
  20         struct file *file;
  21         char interp[128];
  22         int retval;
  23
  24         if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!') || (bprm->sh_bang))
  25                 return -ENOEXEC;
  26         /*
  27          * This section does the #! interpretation.
  28          * Sorta complicated, but hopefully it will work.  -TYT
  29          */
  30
  31         bprm->sh_bang++;
  32         fput(bprm->file);
  33         bprm->file = NULL;
  34
  35         bprm->buf[127] = '\0';
  36         if ((cp = strchr(bprm->buf, '\n')) == NULL)
  37                 cp = bprm->buf+127;
  38         *cp = '\0';
  39         while (cp > bprm->buf) {
  40                 cp--;
  41                 if ((*cp == ' ') || (*cp == '\t'))
  42                         *cp = '\0';
  43                 else
  44                         break;
  45         }
  46         for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++);
  47         if (*cp == '\0')
  48                 return -ENOEXEC; /* No interpreter name found */
  49         i_name = cp;
  50         i_arg = 0;
  51         for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++)
  52                 /* nothing */ ;
  53         while ((*cp == ' ') || (*cp == '\t'))
  54                 *cp++ = '\0';
  55         if (*cp)
  56                 i_arg = cp;
  57         strcpy (interp, i_name);
  58         /*
  59          * OK, we've parsed out the interpreter name and
  60          * (optional) argument.
  61          * Splice in (1) the interpreter's name for argv[0]
  62          *           (2) (optional) argument to interpreter
  63          *           (3) filename of shell script (replace argv[0])
  64          *
  65          * This is done in reverse order, because of how the
  66          * user environment and arguments are stored.
  67          */
  68         remove_arg_zero(bprm);
  69         retval = copy_strings_kernel(1, &bprm->filename, bprm);
  70         if (retval < 0) return retval;
  71         bprm->argc++;
  72         if (i_arg) {
  73                 retval = copy_strings_kernel(1, &i_arg, bprm);
  74                 if (retval < 0) return retval;
  75                 bprm->argc++;
  76         }
  77         retval = copy_strings_kernel(1, &i_name, bprm);
  78         if (retval) return retval;
  79         bprm->argc++;
  80         /*
  81          * OK, now restart the process with the interpreter's dentry.
  82          */
  83         file = open_exec(interp);
  84         if (IS_ERR(file))
  85                 return PTR_ERR(file);
  86
  87         bprm->file = file;
  88         retval = prepare_binprm(bprm);
  89         if (retval < 0)
  90                 return retval;
  91         return search_binary_handler(bprm,regs);
  92 }
  93
  94 struct linux_binfmt script_format = {
  95         NULL, THIS_MODULE, load_script, NULL, NULL, 0
  96 };
  97
  98 static int __init init_script_binfmt(void)
  99 {
 100         return register_binfmt(&script_format);
 101 }
 102
 103 static void __exit exit_script_binfmt(void)
 104 {
 105         unregister_binfmt(&script_format);
 106 }
 107
 108 module_init(init_script_binfmt)
 109 module_exit(exit_script_binfmt)