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/smp_lock.h>
  16 #include <linux/binfmts.h>
  17 #include <linux/elf.h>
  18 #include <linux/init.h>
  19 #include <linux/fs.h>
  20 #include <linux/file.h>
  21 #include <linux/errno.h>
  22
  23
  24 #define EM86_INTERP     "/usr/bin/em86"
  25 #define EM86_I_NAME     "em86"
  26
  27 static int load_em86(struct linux_binprm *bprm,struct pt_regs *regs)
  28 {
  29         char *interp, *i_name, *i_arg;
  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 || !bprm->file->f_op->mmap)) {
  44                         return -ENOEXEC;
  45         }
  46
  47         bprm->sh_bang++;        /* Well, the bang-shell is implicit... */
  48         allow_write_access(bprm->file);
  49         fput(bprm->file);
  50         bprm->file = NULL;
  51
  52         /* Unlike in the script case, we don't have to do any hairy
  53          * parsing to find our interpreter... it's hardcoded!
  54          */
  55         interp = EM86_INTERP;
  56         i_name = EM86_I_NAME;
  57         i_arg = NULL;           /* We reserve the right to add an arg later */
  58
  59         /*
  60          * Splice in (1) the interpreter's name for argv[0]
  61          *           (2) (optional) argument to interpreter
  62          *           (3) filename of emulated file (replace argv[0])
  63          *
  64          * This is done in reverse order, because of how the
  65          * user environment and arguments are stored.
  66          */
  67         remove_arg_zero(bprm);
  68         retval = copy_strings_kernel(1, &bprm->filename, bprm);
  69         if (retval < 0) return retval;
  70         bprm->argc++;
  71         if (i_arg) {
  72                 retval = copy_strings_kernel(1, &i_arg, bprm);
  73                 if (retval < 0) return retval;
  74                 bprm->argc++;
  75         }
  76         retval = copy_strings_kernel(1, &i_name, bprm);
  77         if (retval < 0) return retval;
  78         bprm->argc++;
  79
  80         /*
  81          * OK, now restart the process with the interpreter's inode.
  82          * Note that we use open_exec() as the name is now in kernel
  83          * space, and we don't need to copy it.
  84          */
  85         file = open_exec(interp);
  86         if (IS_ERR(file))
  87                 return PTR_ERR(file);
  88
  89         bprm->file = file;
  90
  91         retval = prepare_binprm(bprm);
  92         if (retval < 0)
  93                 return retval;
  94
  95         return search_binary_handler(bprm, regs);
  96 }
  97
  98 static struct linux_binfmt em86_format = {
  99         .module         = THIS_MODULE,
 100         .load_binary    = load_em86,
 101 };
 102
 103 static int __init init_em86_binfmt(void)
 104 {
 105         return register_binfmt(&em86_format);
 106 }
 107
 108 static void __exit exit_em86_binfmt(void)
 109 {
 110         unregister_binfmt(&em86_format);
 111 }
 112
 113 core_initcall(init_em86_binfmt);
 114 module_exit(exit_em86_binfmt);
 115 MODULE_LICENSE("GPL");