linux/fs/binfmt_em86.c
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   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        register_binfmt(&em86_format);
 104        return 0;
 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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