binfmt_em86.c 2.76 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3 4
/*
 *  linux/fs/binfmt_em86.c
 *
 *  Based on linux/fs/binfmt_script.c
5
 *  Copyright (C) 1996  Martin von Löwis
Linus Torvalds's avatar
Linus Torvalds committed
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44
 *  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/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;
	}

45
	bprm->recursion_depth++; /* Well, the bang-shell is implicit... */
Linus Torvalds's avatar
Linus Torvalds committed
46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102
	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)
{
Al Viro's avatar
Al Viro committed
103 104
	register_binfmt(&em86_format);
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
105 106 107 108 109 110 111 112 113 114
}

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

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