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 do_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 (elf_ex.e_ident[0] != 0x7f ||
  34             strncmp(&elf_ex.e_ident[1], "ELF",3) != 0) {
  35                 return  -ENOEXEC;
  36         }
  37
  38
  39         /* First of all, some simple consistency checks */
  40         if ((elf_ex.e_type != ET_EXEC &&
  41             elf_ex.e_type != ET_DYN) ||
  42            (!((elf_ex.e_machine == EM_386) || (elf_ex.e_machine == EM_486))) ||
  43            (!bprm->dentry->d_inode->i_op || !bprm->dentry->d_inode->i_op->default_file_ops ||
  44             !bprm->dentry->d_inode->i_op->default_file_ops->mmap)){
  45                 return -ENOEXEC;
  46         }
  47
  48         bprm->sh_bang++;        /* Well, the bang-shell is implicit... */
  49         dput(bprm->dentry);
  50         bprm->dentry = 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         bprm->p = copy_strings(1, &bprm->filename, bprm->page, bprm->p, 2);
  69         bprm->argc++;
  70         if (i_arg) {
  71                 bprm->p = copy_strings(1, &i_arg, bprm->page, bprm->p, 2);
  72                 bprm->argc++;
  73         }
  74         bprm->p = copy_strings(1, &i_name, bprm->page, bprm->p, 2);
  75         bprm->argc++;
  76         if (!bprm->p)
  77                 return -E2BIG;
  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         dentry = open_namei(interp, 0, 0);
  84         if (IS_ERR(dentry))
  85                 return PTR_ERR(dentry);
  86
  87         bprm->dentry = dentry;
  88
  89         retval = prepare_binprm(bprm);
  90         if (retval < 0)
  91                 return retval;
  92
  93         return search_binary_handler(bprm, regs);
  94 }
  95
  96 static int load_em86(struct linux_binprm *bprm,struct pt_regs *regs)
  97 {
  98         int retval;
  99         MOD_INC_USE_COUNT;
 100         retval = do_load_em86(bprm,regs);
 101         MOD_DEC_USE_COUNT;
 102         return retval;
 103 }
 104
 105 struct linux_binfmt em86_format = {
 106 #ifndef MODULE
 107         NULL, 0, load_em86, NULL, NULL
 108 #else
 109         NULL, &__this_module, load_em86, NULL, NULL
 110 #endif
 111 };
 112
 113 int __init init_em86_binfmt(void)
 114 {
 115         return register_binfmt(&em86_format);
 116 }
 117
 118 #ifdef MODULE
 119 int init_module(void)
 120 {
 121         return init_em86_binfmt();
 122 }
 123
 124 void cleanup_module( void) {
 125         unregister_binfmt(&em86_format);
 126 }
 127 #endif