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
  26 static 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->sh_bang++;        /* 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
  97 static struct linux_binfmt em86_format = {
  98         .module         = THIS_MODULE,
  99         .load_binary    = load_em86,
 100 };
 101
 102 static int __init init_em86_binfmt(void)
 103 {
 104         return register_binfmt(&em86_format);
 105 }
 106
 107 static void __exit exit_em86_binfmt(void)
 108 {
 109         unregister_binfmt(&em86_format);
 110 }
 111
 112 core_initcall(init_em86_binfmt);
 113 module_exit(exit_em86_binfmt);
 114 MODULE_LICENSE("GPL");