1/*
  2 *  linux/fs/binfmt_em86.c
  3 *
  4 *  Based on linux/fs/binfmt_script.c
  5 *  Copyright (C) 1996  Martin von Löwis
  6 *  original #!-checking implemented by tytso.
  7 *
  8 *  em86 changes Copyright (C) 1997  Jim Paradis
  9 */
 10
 11#include <linux/module.h>
 12#include <linux/string.h>
 13#include <linux/stat.h>
 14#include <linux/binfmts.h>
 15#include <linux/elf.h>
 16#include <linux/init.h>
 17#include <linux/fs.h>
 18#include <linux/file.h>
 19#include <linux/errno.h>
 20
 21
 22#define EM86_INTERP	"/usr/bin/em86"
 23#define EM86_I_NAME	"em86"
 24
 25static int load_em86(struct linux_binprm *bprm)
 26{
 27	const char *i_name, *i_arg;
 28	char *interp;
 29	struct file * file;
 30	int retval;
 31	struct elfhdr	elf_ex;
 32
 33	/* Make sure this is a Linux/Intel ELF executable... */
 34	elf_ex = *((struct elfhdr *)bprm->buf);
 35
 36	if (memcmp(elf_ex.e_ident, ELFMAG, SELFMAG) != 0)
 37		return  -ENOEXEC;
 38
 39	/* First of all, some simple consistency checks */
 40	if ((elf_ex.e_type != ET_EXEC && elf_ex.e_type != ET_DYN) ||
 41		(!((elf_ex.e_machine == EM_386) || (elf_ex.e_machine == EM_486))) ||
 42		!bprm->file->f_op->mmap) {
 43			return -ENOEXEC;
 44	}
 45
 46	/* Need to be able to load the file after exec */
 47	if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE)
 48		return -ENOENT;
 49
 50	allow_write_access(bprm->file);
 51	fput(bprm->file);
 52	bprm->file = NULL;
 53
 54	/* Unlike in the script case, we don't have to do any hairy
 55	 * parsing to find our interpreter... it's hardcoded!
 56	 */
 57	interp = EM86_INTERP;
 58	i_name = EM86_I_NAME;
 59	i_arg = NULL;		/* We reserve the right to add an arg later */
 60
 61	/*
 62	 * Splice in (1) the interpreter's name for argv[0]
 63	 *           (2) (optional) argument to interpreter
 64	 *           (3) filename of emulated file (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 < 0)	return retval;
 80	bprm->argc++;
 81
 82	/*
 83	 * OK, now restart the process with the interpreter's inode.
 84	 * Note that we use open_exec() as the name is now in kernel
 85	 * space, and we don't need to copy it.
 86	 */
 87	file = open_exec(interp);
 88	if (IS_ERR(file))
 89		return PTR_ERR(file);
 90
 91	bprm->file = file;
 92
 93	retval = prepare_binprm(bprm);
 94	if (retval < 0)
 95		return retval;
 96
 97	return search_binary_handler(bprm);
 98}
 99
100static struct linux_binfmt em86_format = {
101	.module		= THIS_MODULE,
102	.load_binary	= load_em86,
103};
104
105static int __init init_em86_binfmt(void)
106{
107	register_binfmt(&em86_format);
108	return 0;
109}
110
111static void __exit exit_em86_binfmt(void)
112{
113	unregister_binfmt(&em86_format);
114}
115
116core_initcall(init_em86_binfmt);
117module_exit(exit_em86_binfmt);
118MODULE_LICENSE("GPL");