Root/fs/binfmt_em86.c

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,struct pt_regs *regs)
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 || !bprm->file->f_op->mmap)) {
42            return -ENOEXEC;
43    }
44
45    bprm->recursion_depth++; /* Well, the bang-shell is implicit... */
46    allow_write_access(bprm->file);
47    fput(bprm->file);
48    bprm->file = NULL;
49
50    /* Unlike in the script case, we don't have to do any hairy
51     * parsing to find our interpreter... it's hardcoded!
52     */
53    interp = EM86_INTERP;
54    i_name = EM86_I_NAME;
55    i_arg = NULL; /* We reserve the right to add an arg later */
56
57    /*
58     * Splice in (1) the interpreter's name for argv[0]
59     * (2) (optional) argument to interpreter
60     * (3) filename of emulated file (replace argv[0])
61     *
62     * This is done in reverse order, because of how the
63     * user environment and arguments are stored.
64     */
65    remove_arg_zero(bprm);
66    retval = copy_strings_kernel(1, &bprm->filename, bprm);
67    if (retval < 0) return retval;
68    bprm->argc++;
69    if (i_arg) {
70        retval = copy_strings_kernel(1, &i_arg, bprm);
71        if (retval < 0) return retval;
72        bprm->argc++;
73    }
74    retval = copy_strings_kernel(1, &i_name, bprm);
75    if (retval < 0) return retval;
76    bprm->argc++;
77
78    /*
79     * OK, now restart the process with the interpreter's inode.
80     * Note that we use open_exec() as the name is now in kernel
81     * space, and we don't need to copy it.
82     */
83    file = open_exec(interp);
84    if (IS_ERR(file))
85        return PTR_ERR(file);
86
87    bprm->file = file;
88
89    retval = prepare_binprm(bprm);
90    if (retval < 0)
91        return retval;
92
93    return search_binary_handler(bprm, regs);
94}
95
96static struct linux_binfmt em86_format = {
97    .module = THIS_MODULE,
98    .load_binary = load_em86,
99};
100
101static int __init init_em86_binfmt(void)
102{
103    return register_binfmt(&em86_format);
104}
105
106static void __exit exit_em86_binfmt(void)
107{
108    unregister_binfmt(&em86_format);
109}
110
111core_initcall(init_em86_binfmt);
112module_exit(exit_em86_binfmt);
113MODULE_LICENSE("GPL");
114

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