LXR linux/fs/binfmt

   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
  18static 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
  98static struct linux_binfmt script_format = {
  99        .module         = THIS_MODULE,
 100        .load_binary    = load_script,
 101};
 102
 103static int __init init_script_binfmt(void)
 104{
 105        return register_binfmt(&script_format);
 106}
 107
 108static void __exit exit_script_binfmt(void)
 109{
 110        unregister_binfmt(&script_format);
 111}
 112
 113core_initcall(init_script_binfmt);
 114module_exit(exit_script_binfmt);
 115MODULE_LICENSE("GPL");
 116