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