LXR linux/fs/binfmt

   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/binfmts.h>
  12#include <linux/init.h>
  13#include <linux/file.h>
  14#include <linux/err.h>
  15#include <linux/fs.h>
  16
  17static int load_script(struct linux_binprm *bprm)
  18{
  19        const char *i_arg, *i_name;
  20        char *cp;
  21        struct file *file;
  22        char interp[BINPRM_BUF_SIZE];
  23        int retval;
  24
  25        if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!'))
  26                return -ENOEXEC;
  27        /*
  28         * This section does the #! interpretation.
  29         * Sorta complicated, but hopefully it will work.  -TYT
  30         */
  31
  32        allow_write_access(bprm->file);
  33        fput(bprm->file);
  34        bprm->file = NULL;
  35
  36        bprm->buf[BINPRM_BUF_SIZE - 1] = '\0';
  37        if ((cp = strchr(bprm->buf, '\n')) == NULL)
  38                cp = bprm->buf+BINPRM_BUF_SIZE-1;
  39        *cp = '\0';
  40        while (cp > bprm->buf) {
  41                cp--;
  42                if ((*cp == ' ') || (*cp == '\t'))
  43                        *cp = '\0';
  44                else
  45                        break;
  46        }
  47        for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++);
  48        if (*cp == '\0') 
  49                return -ENOEXEC; /* No interpreter name found */
  50        i_name = cp;
  51        i_arg = NULL;
  52        for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++)
  53                /* nothing */ ;
  54        while ((*cp == ' ') || (*cp == '\t'))
  55                *cp++ = '\0';
  56        if (*cp)
  57                i_arg = cp;
  58        strcpy (interp, i_name);
  59        /*
  60         * OK, we've parsed out the interpreter name and
  61         * (optional) argument.
  62         * Splice in (1) the interpreter's name for argv[0]
  63         *           (2) (optional) argument to interpreter
  64         *           (3) filename of shell script (replace argv[0])
  65         *
  66         * This is done in reverse order, because of how the
  67         * user environment and arguments are stored.
  68         */
  69        retval = remove_arg_zero(bprm);
  70        if (retval)
  71                return retval;
  72        retval = copy_strings_kernel(1, &bprm->interp, bprm);
  73        if (retval < 0) return retval; 
  74        bprm->argc++;
  75        if (i_arg) {
  76                retval = copy_strings_kernel(1, &i_arg, bprm);
  77                if (retval < 0) return retval; 
  78                bprm->argc++;
  79        }
  80        retval = copy_strings_kernel(1, &i_name, bprm);
  81        if (retval) return retval; 
  82        bprm->argc++;
  83        retval = bprm_change_interp(interp, bprm);
  84        if (retval < 0)
  85                return retval;
  86
  87        /*
  88         * OK, now restart the process with the interpreter's dentry.
  89         */
  90        file = open_exec(interp);
  91        if (IS_ERR(file))
  92                return PTR_ERR(file);
  93
  94        bprm->file = file;
  95        retval = prepare_binprm(bprm);
  96        if (retval < 0)
  97                return retval;
  98        return search_binary_handler(bprm);
  99}
 100
 101static struct linux_binfmt script_format = {
 102        .module         = THIS_MODULE,
 103        .load_binary    = load_script,
 104};
 105
 106static int __init init_script_binfmt(void)
 107{
 108        register_binfmt(&script_format);
 109        return 0;
 110}
 111
 112static void __exit exit_script_binfmt(void)
 113{
 114        unregister_binfmt(&script_format);
 115}
 116
 117core_initcall(init_script_binfmt);
 118module_exit(exit_script_binfmt);
 119MODULE_LICENSE("GPL");
 120