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/slab.h>
15#include <linux/binfmts.h>
16#include <linux/elf.h>
17#include <linux/init.h>
18#include <linux/fs.h>
19#include <linux/file.h>
20#include <linux/errno.h>
21
22
23#define EM86_INTERP "/usr/bin/em86"
24#define EM86_I_NAME "em86"
25
26static int load_em86(struct linux_binprm *bprm,struct pt_regs *regs)
27{
28    char *interp, *i_name, *i_arg;
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 || !bprm->file->f_op->mmap)) {
43            return -ENOEXEC;
44    }
45
46    bprm->recursion_depth++; /* Well, the bang-shell is implicit... */
47    allow_write_access(bprm->file);
48    fput(bprm->file);
49    bprm->file = NULL;
50
51    /* Unlike in the script case, we don't have to do any hairy
52     * parsing to find our interpreter... it's hardcoded!
53     */
54    interp = EM86_INTERP;
55    i_name = EM86_I_NAME;
56    i_arg = NULL; /* We reserve the right to add an arg later */
57
58    /*
59     * Splice in (1) the interpreter's name for argv[0]
60     * (2) (optional) argument to interpreter
61     * (3) filename of emulated file (replace argv[0])
62     *
63     * This is done in reverse order, because of how the
64     * user environment and arguments are stored.
65     */
66    remove_arg_zero(bprm);
67    retval = copy_strings_kernel(1, &bprm->filename, bprm);
68    if (retval < 0) return retval;
69    bprm->argc++;
70    if (i_arg) {
71        retval = copy_strings_kernel(1, &i_arg, bprm);
72        if (retval < 0) return retval;
73        bprm->argc++;
74    }
75    retval = copy_strings_kernel(1, &i_name, bprm);
76    if (retval < 0) return retval;
77    bprm->argc++;
78
79    /*
80     * OK, now restart the process with the interpreter's inode.
81     * Note that we use open_exec() as the name is now in kernel
82     * space, and we don't need to copy it.
83     */
84    file = open_exec(interp);
85    if (IS_ERR(file))
86        return PTR_ERR(file);
87
88    bprm->file = file;
89
90    retval = prepare_binprm(bprm);
91    if (retval < 0)
92        return retval;
93
94    return search_binary_handler(bprm, regs);
95}
96
97static struct linux_binfmt em86_format = {
98    .module = THIS_MODULE,
99    .load_binary = load_em86,
100};
101
102static int __init init_em86_binfmt(void)
103{
104    return register_binfmt(&em86_format);
105}
106
107static void __exit exit_em86_binfmt(void)
108{
109    unregister_binfmt(&em86_format);
110}
111
112core_initcall(init_em86_binfmt);
113module_exit(exit_em86_binfmt);
114MODULE_LICENSE("GPL");
115

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