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/malloc.h>
  15 #include <linux/binfmts.h>
  16 #include <linux/elf.h>
  17 #include <linux/init.h>
  18
  19
  20 #define EM86_INTERP     "/usr/bin/em86"
  21 #define EM86_I_NAME     "em86"
  22
  23 static int load_em86(struct linux_binprm *bprm,struct pt_regs *regs)
  24 {
  25         char *interp, *i_name, *i_arg;
  26         struct dentry * dentry;
  27         int retval;
  28         struct elfhdr   elf_ex;
  29
  30         /* Make sure this is a Linux/Intel ELF executable... */
  31         elf_ex = *((struct elfhdr *)bprm->buf);
  32
  33         if (memcmp(elf_ex.e_ident, ELFMAG, SELFMAG) != 0)
  34                 return  -ENOEXEC;
  35
  36         /* First of all, some simple consistency checks */
  37         if ((elf_ex.e_type != ET_EXEC && elf_ex.e_type != ET_DYN) ||
  38                 (!((elf_ex.e_machine == EM_386) || (elf_ex.e_machine == EM_486))) ||
  39                 (!bprm->dentry->d_inode->i_fop ||
  40                 !bprm->dentry->d_inode->i_fop->mmap)) {
  41                         return -ENOEXEC;
  42         }
  43
  44         bprm->sh_bang++;        /* Well, the bang-shell is implicit... */
  45         lock_kernel();
  46         dput(bprm->dentry);
  47         unlock_kernel();
  48         bprm->dentry = 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_namei() as the name is now in kernel
  81          * space, and we don't need to copy it.
  82          */
  83         lock_kernel();
  84         dentry = open_namei(interp, 0, 0);
  85         unlock_kernel();
  86         if (IS_ERR(dentry))
  87                 return PTR_ERR(dentry);
  88
  89         bprm->dentry = dentry;
  90
  91         retval = prepare_binprm(bprm);
  92         if (retval < 0)
  93                 return retval;
  94
  95         return search_binary_handler(bprm, regs);
  96 }
  97
  98 struct linux_binfmt em86_format = {
  99         NULL, THIS_MODULE, load_em86, NULL, NULL, 0
 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 module_init(init_em86_binfmt)
 113 module_exit(exit_em86_binfmt)