1/*
2 *  linux/fs/binfmt_script.c
3 *
4 *  Copyright (C) 1996  Martin von L��wis
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,struct pt_regs *regs)
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	    (bprm->recursion_depth > BINPRM_MAX_RECURSION))
27		return -ENOEXEC;
28	/*
29	 * This section does the #! interpretation.
30	 * Sorta complicated, but hopefully it will work.  -TYT
31	 */
32
33	bprm->recursion_depth++;
34	allow_write_access(bprm->file);
35	fput(bprm->file);
36	bprm->file = NULL;
37
38	bprm->buf[BINPRM_BUF_SIZE - 1] = '\0';
39	if ((cp = strchr(bprm->buf, '\n')) == NULL)
40		cp = bprm->buf+BINPRM_BUF_SIZE-1;
41	*cp = '\0';
42	while (cp > bprm->buf) {
43		cp--;
44		if ((*cp == ' ') || (*cp == '\t'))
45			*cp = '\0';
46		else
47			break;
48	}
49	for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++);
50	if (*cp == '\0')
51		return -ENOEXEC; /* No interpreter name found */
52	i_name = cp;
53	i_arg = NULL;
54	for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++)
55		/* nothing */ ;
56	while ((*cp == ' ') || (*cp == '\t'))
57		*cp++ = '\0';
58	if (*cp)
59		i_arg = cp;
60	strcpy (interp, i_name);
61	/*
62	 * OK, we've parsed out the interpreter name and
63	 * (optional) argument.
64	 * Splice in (1) the interpreter's name for argv[0]
65	 *           (2) (optional) argument to interpreter
66	 *           (3) filename of shell script (replace argv[0])
67	 *
68	 * This is done in reverse order, because of how the
69	 * user environment and arguments are stored.
70	 */
71	retval = remove_arg_zero(bprm);
72	if (retval)
73		return retval;
74	retval = copy_strings_kernel(1, &bprm->interp, bprm);
75	if (retval < 0) return retval;
76	bprm->argc++;
77	if (i_arg) {
78		retval = copy_strings_kernel(1, &i_arg, bprm);
79		if (retval < 0) return retval;
80		bprm->argc++;
81	}
82	retval = copy_strings_kernel(1, &i_name, bprm);
83	if (retval) return retval;
84	bprm->argc++;
85	bprm->interp = interp;
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,regs);
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	return register_binfmt(&script_format);
109}
110
111static void __exit exit_script_binfmt(void)
112{
113	unregister_binfmt(&script_format);
114}
115
116core_initcall(init_script_binfmt);
117module_exit(exit_script_binfmt);
118MODULE_LICENSE("GPL");
119