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	char *interp, *i_name, *i_arg;
28	struct file * file;
29	int retval;
30	struct elfhdr	elf_ex;
31
32	/* Make sure this is a Linux/Intel ELF executable... */
33	elf_ex = *((struct elfhdr *)bprm->buf);
34
35	if (memcmp(elf_ex.e_ident, ELFMAG, SELFMAG) != 0)
36		return  -ENOEXEC;
37
38	/* First of all, some simple consistency checks */
39	if ((elf_ex.e_type != ET_EXEC && elf_ex.e_type != ET_DYN) ||
40		(!((elf_ex.e_machine == EM_386) || (elf_ex.e_machine == EM_486))) ||
41		!bprm->file->f_op->mmap) {
42			return -ENOEXEC;
43	}
44
45	/* Need to be able to load the file after exec */
46	if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE)
47		return -ENOENT;
48
49	allow_write_access(bprm->file);
50	fput(bprm->file);
51	bprm->file = NULL;
52
53	/* Unlike in the script case, we don't have to do any hairy
54	 * parsing to find our interpreter... it's hardcoded!
55	 */
56	interp = EM86_INTERP;
57	i_name = EM86_I_NAME;
58	i_arg = NULL;		/* We reserve the right to add an arg later */
59
60	/*
61	 * Splice in (1) the interpreter's name for argv[0]
62	 *           (2) (optional) argument to interpreter
63	 *           (3) filename of emulated file (replace argv[0])
64	 *
65	 * This is done in reverse order, because of how the
66	 * user environment and arguments are stored.
67	 */
68	remove_arg_zero(bprm);
69	retval = copy_strings_kernel(1, &bprm->filename, bprm);
70	if (retval < 0) return retval;
71	bprm->argc++;
72	if (i_arg) {
73		retval = copy_strings_kernel(1, &i_arg, bprm);
74		if (retval < 0) return retval;
75		bprm->argc++;
76	}
77	retval = copy_strings_kernel(1, &i_name, bprm);
78	if (retval < 0)	return retval;
79	bprm->argc++;
80
81	/*
82	 * OK, now restart the process with the interpreter's inode.
83	 * Note that we use open_exec() as the name is now in kernel
84	 * space, and we don't need to copy it.
85	 */
86	file = open_exec(interp);
87	if (IS_ERR(file))
88		return PTR_ERR(file);
89
90	bprm->file = file;
91
92	retval = prepare_binprm(bprm);
93	if (retval < 0)
94		return retval;
95
96	return search_binary_handler(bprm);
97}
98
99static struct linux_binfmt em86_format = {
100	.module		= THIS_MODULE,
101	.load_binary	= load_em86,
102};
103
104static int __init init_em86_binfmt(void)
105{
106	register_binfmt(&em86_format);
107	return 0;
108}
109
110static void __exit exit_em86_binfmt(void)
111{
112	unregister_binfmt(&em86_format);
113}
114
115core_initcall(init_em86_binfmt);
116module_exit(exit_em86_binfmt);
117MODULE_LICENSE("GPL");
118