fs/binfmt_script.c

   1 /*
   2  *  linux/fs/binfmt_script.c
   3  *
   4  *  Copyright (C) 1996  Martin von Löwis
   5  *  original #!-checking implemented by tytso.
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/string.h>
  10 #include <linux/stat.h>
  11 #include <linux/malloc.h>
  12 #include <linux/binfmts.h>
  13 #include <linux/init.h>
  14
  15 static int do_load_script(struct linux_binprm *bprm,struct pt_regs *regs)
  16 {
  17         char *cp, *i_name, *i_name_start, *i_arg;
  18         struct dentry * dentry;
  19         char interp[128];
  20         int retval;
  21
  22         if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!') || (bprm->sh_bang))
  23                 return -ENOEXEC;
  24         /*
  25          * This section does the #! interpretation.
  26          * Sorta complicated, but hopefully it will work.  -TYT
  27          */
  28
  29         bprm->sh_bang++;
  30         dput(bprm->dentry);
  31         bprm->dentry = NULL;
  32
  33         bprm->buf[127] = '\0';
  34         if ((cp = strchr(bprm->buf, '\n')) == NULL)
  35                 cp = bprm->buf+127;
  36         *cp = '\0';
  37         while (cp > bprm->buf) {
  38                 cp--;
  39                 if ((*cp == ' ') || (*cp == '\t'))
  40                         *cp = '\0';
  41                 else
  42                         break;
  43         }
  44         for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++);
  45         if (*cp == '\0')
  46                 return -ENOEXEC; /* No interpreter name found */
  47         i_name_start = i_name = cp;
  48         i_arg = 0;
  49         for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++) {
  50                 if (*cp == '/')
  51                         i_name = cp+1;
  52         }
  53         while ((*cp == ' ') || (*cp == '\t'))
  54                 *cp++ = '\0';
  55         if (*cp)
  56                 i_arg = cp;
  57         strcpy (interp, i_name_start);
  58         /*
  59          * OK, we've parsed out the interpreter name and
  60          * (optional) argument.
  61          * Splice in (1) the interpreter's name for argv[0]
  62          *           (2) (optional) argument to interpreter
  63          *           (3) filename of shell script (replace argv[0])
  64          *
  65          * This is done in reverse order, because of how the
  66          * user environment and arguments are stored.
  67          */
  68         remove_arg_zero(bprm);
  69         retval = copy_strings_kernel(1, &bprm->filename, bprm);
  70         if (retval < 0) return retval;
  71         bprm->argc++;
  72         if (i_arg) {
  73                 retval = copy_strings_kernel(1, &i_arg, bprm);
  74                 if (retval < 0) return retval;
  75                 bprm->argc++;
  76         }
  77         retval = copy_strings_kernel(1, &i_name, bprm);
  78         if (retval) return retval;
  79         bprm->argc++;
  80         /*
  81          * OK, now restart the process with the interpreter's dentry.
  82          */
  83         dentry = open_namei(interp, 0, 0);
  84         if (IS_ERR(dentry))
  85                 return PTR_ERR(dentry);
  86
  87         bprm->dentry = dentry;
  88         retval = prepare_binprm(bprm);
  89         if (retval < 0)
  90                 return retval;
  91         return search_binary_handler(bprm,regs);
  92 }
  93
  94 static int load_script(struct linux_binprm *bprm,struct pt_regs *regs)
  95 {
  96         int retval;
  97         MOD_INC_USE_COUNT;
  98         retval = do_load_script(bprm,regs);
  99         MOD_DEC_USE_COUNT;
 100         return retval;
 101 }
 102
 103 struct linux_binfmt script_format = {
 104         NULL,
 105 #ifndef MODULE
 106         NULL,
 107 #else
 108         &__this_module,
 109 #endif
 110         load_script, NULL, NULL, 0
 111 };
 112
 113 int __init init_script_binfmt(void)
 114 {
 115         return register_binfmt(&script_format);
 116 }
 117
 118 #ifdef MODULE
 119 int init_module(void)
 120 {
 121         return init_script_binfmt();
 122 }
 123
 124 void cleanup_module( void) {
 125         unregister_binfmt(&script_format);
 126 }
 127 #endif