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