binfmt_script.c 2.96 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3
/*
 *  linux/fs/binfmt_script.c
 *
4
 *  Copyright (C) 1996  Martin von Löwis
Linus Torvalds's avatar
Linus Torvalds committed
5 6 7 8 9 10 11 12 13 14 15 16
 *  original #!-checking implemented by tytso.
 */

#include <linux/module.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/binfmts.h>
#include <linux/init.h>
#include <linux/file.h>
#include <linux/err.h>
#include <linux/fs.h>

17
static int load_script(struct linux_binprm *bprm)
Linus Torvalds's avatar
Linus Torvalds committed
18
{
19 20
	const char *i_arg, *i_name;
	char *cp;
Linus Torvalds's avatar
Linus Torvalds committed
21 22 23
	struct file *file;
	int retval;

24
	if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!'))
Linus Torvalds's avatar
Linus Torvalds committed
25
		return -ENOEXEC;
26 27 28 29 30 31 32 33 34 35

	/*
	 * If the script filename will be inaccessible after exec, typically
	 * because it is a "/dev/fd/<fd>/.." path against an O_CLOEXEC fd, give
	 * up now (on the assumption that the interpreter will want to load
	 * this file).
	 */
	if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE)
		return -ENOENT;

Linus Torvalds's avatar
Linus Torvalds committed
36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56
	/*
	 * This section does the #! interpretation.
	 * Sorta complicated, but hopefully it will work.  -TYT
	 */

	allow_write_access(bprm->file);
	fput(bprm->file);
	bprm->file = NULL;

	bprm->buf[BINPRM_BUF_SIZE - 1] = '\0';
	if ((cp = strchr(bprm->buf, '\n')) == NULL)
		cp = bprm->buf+BINPRM_BUF_SIZE-1;
	*cp = '\0';
	while (cp > bprm->buf) {
		cp--;
		if ((*cp == ' ') || (*cp == '\t'))
			*cp = '\0';
		else
			break;
	}
	for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++);
57
	if (*cp == '\0')
Linus Torvalds's avatar
Linus Torvalds committed
58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76
		return -ENOEXEC; /* No interpreter name found */
	i_name = cp;
	i_arg = NULL;
	for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++)
		/* nothing */ ;
	while ((*cp == ' ') || (*cp == '\t'))
		*cp++ = '\0';
	if (*cp)
		i_arg = cp;
	/*
	 * OK, we've parsed out the interpreter name and
	 * (optional) argument.
	 * Splice in (1) the interpreter's name for argv[0]
	 *           (2) (optional) argument to interpreter
	 *           (3) filename of shell script (replace argv[0])
	 *
	 * This is done in reverse order, because of how the
	 * user environment and arguments are stored.
	 */
77 78 79
	retval = remove_arg_zero(bprm);
	if (retval)
		return retval;
Linus Torvalds's avatar
Linus Torvalds committed
80
	retval = copy_strings_kernel(1, &bprm->interp, bprm);
81 82
	if (retval < 0)
		return retval;
Linus Torvalds's avatar
Linus Torvalds committed
83 84 85
	bprm->argc++;
	if (i_arg) {
		retval = copy_strings_kernel(1, &i_arg, bprm);
86 87
		if (retval < 0)
			return retval;
Linus Torvalds's avatar
Linus Torvalds committed
88 89 90
		bprm->argc++;
	}
	retval = copy_strings_kernel(1, &i_name, bprm);
91 92
	if (retval)
		return retval;
Linus Torvalds's avatar
Linus Torvalds committed
93
	bprm->argc++;
94
	retval = bprm_change_interp(i_name, bprm);
95 96
	if (retval < 0)
		return retval;
Linus Torvalds's avatar
Linus Torvalds committed
97 98 99 100

	/*
	 * OK, now restart the process with the interpreter's dentry.
	 */
101
	file = open_exec(i_name);
Linus Torvalds's avatar
Linus Torvalds committed
102 103 104 105 106 107 108
	if (IS_ERR(file))
		return PTR_ERR(file);

	bprm->file = file;
	retval = prepare_binprm(bprm);
	if (retval < 0)
		return retval;
109
	return search_binary_handler(bprm);
Linus Torvalds's avatar
Linus Torvalds committed
110 111 112 113 114 115 116 117 118
}

static struct linux_binfmt script_format = {
	.module		= THIS_MODULE,
	.load_binary	= load_script,
};

static int __init init_script_binfmt(void)
{
Al Viro's avatar
Al Viro committed
119 120
	register_binfmt(&script_format);
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
121 122 123 124 125 126 127 128 129 130
}

static void __exit exit_script_binfmt(void)
{
	unregister_binfmt(&script_format);
}

core_initcall(init_script_binfmt);
module_exit(exit_script_binfmt);
MODULE_LICENSE("GPL");