root/fs/binfmt_em86.c

DEFINITIONS

1. load_em86
2. init_em86_binfmt
3. exit_em86_binfmt

/*
 *  linux/fs/binfmt_em86.c
 *
 *  Based on linux/fs/binfmt_script.c
 *  Copyright (C) 1996  Martin von Löwis
 *  original #!-checking implemented by tytso.
 *
 *  em86 changes Copyright (C) 1997  Jim Paradis
 */

#include <linux/module.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/slab.h>
#include <linux/binfmts.h>
#include <linux/elf.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/errno.h>


#define EM86_INTERP     "/usr/bin/em86"
#define EM86_I_NAME     "em86"

static int load_em86(struct linux_binprm *bprm,struct pt_regs *regs)
{
        char *interp, *i_name, *i_arg;
        struct file * file;
        int retval;
        struct elfhdr   elf_ex;

        /* Make sure this is a Linux/Intel ELF executable... */
        elf_ex = *((struct elfhdr *)bprm->buf);

        if (memcmp(elf_ex.e_ident, ELFMAG, SELFMAG) != 0)
                return  -ENOEXEC;

        /* First of all, some simple consistency checks */
        if ((elf_ex.e_type != ET_EXEC && elf_ex.e_type != ET_DYN) ||
                (!((elf_ex.e_machine == EM_386) || (elf_ex.e_machine == EM_486))) ||
                (!bprm->file->f_op || !bprm->file->f_op->mmap)) {
                        return -ENOEXEC;
        }

        bprm->sh_bang = 1;      /* Well, the bang-shell is implicit... */
        allow_write_access(bprm->file);
        fput(bprm->file);
        bprm->file = NULL;

        /* Unlike in the script case, we don't have to do any hairy
         * parsing to find our interpreter... it's hardcoded!
         */
        interp = EM86_INTERP;
        i_name = EM86_I_NAME;
        i_arg = NULL;           /* We reserve the right to add an arg later */

        /*
         * Splice in (1) the interpreter's name for argv[0]
         *           (2) (optional) argument to interpreter
         *           (3) filename of emulated file (replace argv[0])
         *
         * This is done in reverse order, because of how the
         * user environment and arguments are stored.
         */
        remove_arg_zero(bprm);
        retval = copy_strings_kernel(1, &bprm->filename, bprm);
        if (retval < 0) return retval; 
        bprm->argc++;
        if (i_arg) {
                retval = copy_strings_kernel(1, &i_arg, bprm);
                if (retval < 0) return retval; 
                bprm->argc++;
        }
        retval = copy_strings_kernel(1, &i_name, bprm);
        if (retval < 0) return retval;
        bprm->argc++;

        /*
         * OK, now restart the process with the interpreter's inode.
         * Note that we use open_exec() as the name is now in kernel
         * space, and we don't need to copy it.
         */
        file = open_exec(interp);
        if (IS_ERR(file))
                return PTR_ERR(file);

        bprm->file = file;

        retval = prepare_binprm(bprm);
        if (retval < 0)
                return retval;

        return search_binary_handler(bprm, regs);
}

static struct linux_binfmt em86_format = {
        .module         = THIS_MODULE,
        .load_binary    = load_em86,
};

static int __init init_em86_binfmt(void)
{
        return register_binfmt(&em86_format);
}

static void __exit exit_em86_binfmt(void)
{
        unregister_binfmt(&em86_format);
}

core_initcall(init_em86_binfmt);
module_exit(exit_em86_binfmt);
MODULE_LICENSE("GPL");