fs/binfmt_em86.c

   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
  26 static 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
 101 static struct linux_binfmt em86_format = {
 102         .module         = THIS_MODULE,
 103         .load_binary    = load_em86,
 104 };
 105
 106 static int __init init_em86_binfmt(void)
 107 {
 108         register_binfmt(&em86_format);
 109         return 0;
 110 }
 111
 112 static void __exit exit_em86_binfmt(void)
 113 {
 114         unregister_binfmt(&em86_format);
 115 }
 116
 117 core_initcall(init_em86_binfmt);
 118 module_exit(exit_em86_binfmt);
 119 MODULE_LICENSE("GPL");