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[BINPRM_BUF_SIZE];
  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         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 = 0;
  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         remove_arg_zero(bprm);
  70         retval = copy_strings_kernel(1, &bprm->filename, bprm);
  71         if (retval < 0) return retval;
  72         bprm->argc++;
  73         if (i_arg) {
  74                 retval = copy_strings_kernel(1, &i_arg, bprm);
  75                 if (retval < 0) return retval;
  76                 bprm->argc++;
  77         }
  78         retval = copy_strings_kernel(1, &i_name, bprm);
  79         if (retval) return retval;
  80         bprm->argc++;
  81         /*
  82          * OK, now restart the process with the interpreter's dentry.
  83          */
  84         file = open_exec(interp);
  85         if (IS_ERR(file))
  86                 return PTR_ERR(file);
  87
  88         bprm->file = file;
  89         retval = prepare_binprm(bprm);
  90         if (retval < 0)
  91                 return retval;
  92         return search_binary_handler(bprm,regs);
  93 }
  94
  95 struct linux_binfmt script_format = {
  96         NULL, THIS_MODULE, load_script, NULL, NULL, 0
  97 };
  98
  99 static int __init init_script_binfmt(void)
 100 {
 101         return register_binfmt(&script_format);
 102 }
 103
 104 static void __exit exit_script_binfmt(void)
 105 {
 106         unregister_binfmt(&script_format);
 107 }
 108
 109 module_init(init_script_binfmt)
 110 module_exit(exit_script_binfmt)