LXR linux/fs/binfmt

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  linux/fs/binfmt_em86.c
   4 *
   5 *  Based on linux/fs/binfmt_script.c
   6 *  Copyright (C) 1996  Martin von Löwis
   7 *  original #!-checking implemented by tytso.
   8 *
   9 *  em86 changes Copyright (C) 1997  Jim Paradis
  10 */
  11
  12#include <linux/module.h>
  13#include <linux/string.h>
  14#include <linux/stat.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)
  27{
  28        const char *i_name, *i_arg;
  29        char *interp;
  30        struct file * file;
  31        int retval;
  32        struct elfhdr   elf_ex;
  33
  34        /* Make sure this is a Linux/Intel ELF executable... */
  35        elf_ex = *((struct elfhdr *)bprm->buf);
  36
  37        if (memcmp(elf_ex.e_ident, ELFMAG, SELFMAG) != 0)
  38                return  -ENOEXEC;
  39
  40        /* First of all, some simple consistency checks */
  41        if ((elf_ex.e_type != ET_EXEC && elf_ex.e_type != ET_DYN) ||
  42                (!((elf_ex.e_machine == EM_386) || (elf_ex.e_machine == EM_486))) ||
  43                !bprm->file->f_op->mmap) {
  44                        return -ENOEXEC;
  45        }
  46
  47        /* Need to be able to load the file after exec */
  48        if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE)
  49                return -ENOENT;
  50
  51        allow_write_access(bprm->file);
  52        fput(bprm->file);
  53        bprm->file = NULL;
  54
  55        /* Unlike in the script case, we don't have to do any hairy
  56         * parsing to find our interpreter... it's hardcoded!
  57         */
  58        interp = EM86_INTERP;
  59        i_name = EM86_I_NAME;
  60        i_arg = NULL;           /* We reserve the right to add an arg later */
  61
  62        /*
  63         * Splice in (1) the interpreter's name for argv[0]
  64         *           (2) (optional) argument to interpreter
  65         *           (3) filename of emulated file (replace argv[0])
  66         *
  67         * This is done in reverse order, because of how the
  68         * user environment and arguments are stored.
  69         */
  70        remove_arg_zero(bprm);
  71        retval = copy_strings_kernel(1, &bprm->filename, bprm);
  72        if (retval < 0) return retval; 
  73        bprm->argc++;
  74        if (i_arg) {
  75                retval = copy_strings_kernel(1, &i_arg, bprm);
  76                if (retval < 0) return retval; 
  77                bprm->argc++;
  78        }
  79        retval = copy_strings_kernel(1, &i_name, bprm);
  80        if (retval < 0) return retval;
  81        bprm->argc++;
  82
  83        /*
  84         * OK, now restart the process with the interpreter's inode.
  85         * Note that we use open_exec() as the name is now in kernel
  86         * space, and we don't need to copy it.
  87         */
  88        file = open_exec(interp);
  89        if (IS_ERR(file))
  90                return PTR_ERR(file);
  91
  92        bprm->file = file;
  93
  94        retval = prepare_binprm(bprm);
  95        if (retval < 0)
  96                return retval;
  97
  98        return search_binary_handler(bprm);
  99}
 100
 101static struct linux_binfmt em86_format = {
 102        .module         = THIS_MODULE,
 103        .load_binary    = load_em86,
 104};
 105
 106static int __init init_em86_binfmt(void)
 107{
 108        register_binfmt(&em86_format);
 109        return 0;
 110}
 111
 112static void __exit exit_em86_binfmt(void)
 113{
 114        unregister_binfmt(&em86_format);
 115}
 116
 117core_initcall(init_em86_binfmt);
 118module_exit(exit_em86_binfmt);
 119MODULE_LICENSE("GPL");
 120