path: root/fs/binfmt_misc.c (plain)
blob: f842261ce97388536104b36e80da6a25016c7f1a

1	/*
2	* binfmt_misc.c
3	*
4	* Copyright (C) 1997 Richard Günther
5	*
6	* binfmt_misc detects binaries via a magic or filename extension and invokes
7	* a specified wrapper. See Documentation/binfmt_misc.txt for more details.
8	*/
9
10	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12	#include <linux/kernel.h>
13	#include <linux/module.h>
14	#include <linux/init.h>
15	#include <linux/sched.h>
16	#include <linux/magic.h>
17	#include <linux/binfmts.h>
18	#include <linux/slab.h>
19	#include <linux/ctype.h>
20	#include <linux/string_helpers.h>
21	#include <linux/file.h>
22	#include <linux/pagemap.h>
23	#include <linux/namei.h>
24	#include <linux/mount.h>
25	#include <linux/syscalls.h>
26	#include <linux/fs.h>
27	#include <linux/uaccess.h>
28
29	#include "internal.h"
30
31	#ifdef DEBUG
32	# define USE_DEBUG 1
33	#else
34	# define USE_DEBUG 0
35	#endif
36
37	enum {
38	VERBOSE_STATUS = 1 /* make it zero to save 400 bytes kernel memory */
39	};
40
41	static LIST_HEAD(entries);
42	static int enabled = 1;
43
44	enum {Enabled, Magic};
45	#define MISC_FMT_PRESERVE_ARGV0 (1 << 31)
46	#define MISC_FMT_OPEN_BINARY (1 << 30)
47	#define MISC_FMT_CREDENTIALS (1 << 29)
48	#define MISC_FMT_OPEN_FILE (1 << 28)
49
50	typedef struct {
51	struct list_head list;
52	unsigned long flags; /* type, status, etc. */
53	int offset; /* offset of magic */
54	int size; /* size of magic/mask */
55	char *magic; /* magic or filename extension */
56	char *mask; /* mask, NULL for exact match */
57	char *interpreter; /* filename of interpreter */
58	char *name;
59	struct dentry *dentry;
60	struct file *interp_file;
61	} Node;
62
63	static DEFINE_RWLOCK(entries_lock);
64	static struct file_system_type bm_fs_type;
65	static struct vfsmount *bm_mnt;
66	static int entry_count;
67
68	/*
69	* Max length of the register string. Determined by:
70	* - 7 delimiters
71	* - name: ~50 bytes
72	* - type: 1 byte
73	* - offset: 3 bytes (has to be smaller than BINPRM_BUF_SIZE)
74	* - magic: 128 bytes (512 in escaped form)
75	* - mask: 128 bytes (512 in escaped form)
76	* - interp: ~50 bytes
77	* - flags: 5 bytes
78	* Round that up a bit, and then back off to hold the internal data
79	* (like struct Node).
80	*/
81	#define MAX_REGISTER_LENGTH 1920
82
83	/*
84	* Check if we support the binfmt
85	* if we do, return the node, else NULL
86	* locking is done in load_misc_binary
87	*/
88	static Node *check_file(struct linux_binprm *bprm)
89	{
90	char *p = strrchr(bprm->interp, '.');
91	struct list_head *l;
92
93	/* Walk all the registered handlers. */
94	list_for_each(l, &entries) {
95	Node *e = list_entry(l, Node, list);
96	char *s;
97	int j;
98
99	/* Make sure this one is currently enabled. */
100	if (!test_bit(Enabled, &e->flags))
101	continue;
102
103	/* Do matching based on extension if applicable. */
104	if (!test_bit(Magic, &e->flags)) {
105	if (p && !strcmp(e->magic, p + 1))
106	return e;
107	continue;
108	}
109
110	/* Do matching based on magic & mask. */
111	s = bprm->buf + e->offset;
112	if (e->mask) {
113	for (j = 0; j < e->size; j++)
114	if ((*s++ ^ e->magic[j]) & e->mask[j])
115	break;
116	} else {
117	for (j = 0; j < e->size; j++)
118	if ((*s++ ^ e->magic[j]))
119	break;
120	}
121	if (j == e->size)
122	return e;
123	}
124	return NULL;
125	}
126
127	/*
128	* the loader itself
129	*/
130	static int load_misc_binary(struct linux_binprm *bprm)
131	{
132	Node *fmt;
133	struct file *interp_file = NULL;
134	char iname[BINPRM_BUF_SIZE];
135	const char *iname_addr = iname;
136	int retval;
137	int fd_binary = -1;
138
139	retval = -ENOEXEC;
140	if (!enabled)
141	goto ret;
142
143	/* to keep locking time low, we copy the interpreter string */
144	read_lock(&entries_lock);
145	fmt = check_file(bprm);
146	if (fmt)
147	strlcpy(iname, fmt->interpreter, BINPRM_BUF_SIZE);
148	read_unlock(&entries_lock);
149	if (!fmt)
150	goto ret;
151
152	/* Need to be able to load the file after exec */
153	if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE)
154	return -ENOENT;
155
156	if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) {
157	retval = remove_arg_zero(bprm);
158	if (retval)
159	goto ret;
160	}
161
162	if (fmt->flags & MISC_FMT_OPEN_BINARY) {
163
164	/* if the binary should be opened on behalf of the
165	* interpreter than keep it open and assign descriptor
166	* to it
167	*/
168	fd_binary = get_unused_fd_flags(0);
169	if (fd_binary < 0) {
170	retval = fd_binary;
171	goto ret;
172	}
173	fd_install(fd_binary, bprm->file);
174
175	/* if the binary is not readable than enforce mm->dumpable=0
176	regardless of the interpreter's permissions */
177	would_dump(bprm, bprm->file);
178
179	allow_write_access(bprm->file);
180	bprm->file = NULL;
181
182	/* mark the bprm that fd should be passed to interp */
183	bprm->interp_flags |= BINPRM_FLAGS_EXECFD;
184	bprm->interp_data = fd_binary;
185
186	} else {
187	allow_write_access(bprm->file);
188	fput(bprm->file);
189	bprm->file = NULL;
190	}
191	/* make argv[1] be the path to the binary */
192	retval = copy_strings_kernel(1, &bprm->interp, bprm);
193	if (retval < 0)
194	goto error;
195	bprm->argc++;
196
197	/* add the interp as argv[0] */
198	retval = copy_strings_kernel(1, &iname_addr, bprm);
199	if (retval < 0)
200	goto error;
201	bprm->argc++;
202
203	/* Update interp in case binfmt_script needs it. */
204	retval = bprm_change_interp(iname, bprm);
205	if (retval < 0)
206	goto error;
207
208	if (fmt->flags & MISC_FMT_OPEN_FILE && fmt->interp_file) {
209	interp_file = filp_clone_open(fmt->interp_file);
210	if (!IS_ERR(interp_file))
211	deny_write_access(interp_file);
212	} else {
213	interp_file = open_exec(iname);
214	}
215	retval = PTR_ERR(interp_file);
216	if (IS_ERR(interp_file))
217	goto error;
218
219	bprm->file = interp_file;
220	if (fmt->flags & MISC_FMT_CREDENTIALS) {
221	/*
222	* No need to call prepare_binprm(), it's already been
223	* done. bprm->buf is stale, update from interp_file.
224	*/
225	memset(bprm->buf, 0, BINPRM_BUF_SIZE);
226	retval = kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE);
227	} else
228	retval = prepare_binprm(bprm);
229
230	if (retval < 0)
231	goto error;
232
233	retval = search_binary_handler(bprm);
234	if (retval < 0)
235	goto error;
236
237	ret:
238	return retval;
239	error:
240	if (fd_binary > 0)
241	sys_close(fd_binary);
242	bprm->interp_flags = 0;
243	bprm->interp_data = 0;
244	goto ret;
245	}
246
247	/* Command parsers */
248
249	/*
250	* parses and copies one argument enclosed in del from *sp to *dp,
251	* recognising the \x special.
252	* returns pointer to the copied argument or NULL in case of an
253	* error (and sets err) or null argument length.
254	*/
255	static char *scanarg(char *s, char del)
256	{
257	char c;
258
259	while ((c = *s++) != del) {
260	if (c == '\\' && *s == 'x') {
261	s++;
262	if (!isxdigit(*s++))
263	return NULL;
264	if (!isxdigit(*s++))
265	return NULL;
266	}
267	}
268	s[-1] ='\0';
269	return s;
270	}
271
272	static char *check_special_flags(char *sfs, Node *e)
273	{
274	char *p = sfs;
275	int cont = 1;
276
277	/* special flags */
278	while (cont) {
279	switch (*p) {
280	case 'P':
281	pr_debug("register: flag: P (preserve argv0)\n");
282	p++;
283	e->flags |= MISC_FMT_PRESERVE_ARGV0;
284	break;
285	case 'O':
286	pr_debug("register: flag: O (open binary)\n");
287	p++;
288	e->flags |= MISC_FMT_OPEN_BINARY;
289	break;
290	case 'C':
291	pr_debug("register: flag: C (preserve creds)\n");
292	p++;
293	/* this flags also implies the
294	open-binary flag */
295	e->flags |= (MISC_FMT_CREDENTIALS |
296	MISC_FMT_OPEN_BINARY);
297	break;
298	case 'F':
299	pr_debug("register: flag: F: open interpreter file now\n");
300	p++;
301	e->flags |= MISC_FMT_OPEN_FILE;
302	break;
303	default:
304	cont = 0;
305	}
306	}
307
308	return p;
309	}
310
311	/*
312	* This registers a new binary format, it recognises the syntax
313	* ':name:type:offset:magic:mask:interpreter:flags'
314	* where the ':' is the IFS, that can be chosen with the first char
315	*/
316	static Node *create_entry(const char __user *buffer, size_t count)
317	{
318	Node *e;
319	int memsize, err;
320	char *buf, *p;
321	char del;
322
323	pr_debug("register: received %zu bytes\n", count);
324
325	/* some sanity checks */
326	err = -EINVAL;
327	if ((count < 11) || (count > MAX_REGISTER_LENGTH))
328	goto out;
329
330	err = -ENOMEM;
331	memsize = sizeof(Node) + count + 8;
332	e = kmalloc(memsize, GFP_KERNEL);
333	if (!e)
334	goto out;
335
336	p = buf = (char *)e + sizeof(Node);
337
338	memset(e, 0, sizeof(Node));
339	if (copy_from_user(buf, buffer, count))
340	goto efault;
341
342	del = *p++; /* delimeter */
343
344	pr_debug("register: delim: %#x {%c}\n", del, del);
345
346	/* Pad the buffer with the delim to simplify parsing below. */
347	memset(buf + count, del, 8);
348
349	/* Parse the 'name' field. */
350	e->name = p;
351	p = strchr(p, del);
352	if (!p)
353	goto einval;
354	*p++ = '\0';
355	if (!e->name[0] ||
356	!strcmp(e->name, ".") ||
357	!strcmp(e->name, "..") ||
358	strchr(e->name, '/'))
359	goto einval;
360
361	pr_debug("register: name: {%s}\n", e->name);
362
363	/* Parse the 'type' field. */
364	switch (*p++) {
365	case 'E':
366	pr_debug("register: type: E (extension)\n");
367	e->flags = 1 << Enabled;
368	break;
369	case 'M':
370	pr_debug("register: type: M (magic)\n");
371	e->flags = (1 << Enabled) | (1 << Magic);
372	break;
373	default:
374	goto einval;
375	}
376	if (*p++ != del)
377	goto einval;
378
379	if (test_bit(Magic, &e->flags)) {
380	/* Handle the 'M' (magic) format. */
381	char *s;
382
383	/* Parse the 'offset' field. */
384	s = strchr(p, del);
385	if (!s)
386	goto einval;
387	*s = '\0';
388	if (p != s) {
389	int r = kstrtoint(p, 10, &e->offset);
390	if (r != 0 || e->offset < 0)
391	goto einval;
392	}
393	p = s;
394	if (*p++)
395	goto einval;
396	pr_debug("register: offset: %#x\n", e->offset);
397
398	/* Parse the 'magic' field. */
399	e->magic = p;
400	p = scanarg(p, del);
401	if (!p)
402	goto einval;
403	if (!e->magic[0])
404	goto einval;
405	if (USE_DEBUG)
406	print_hex_dump_bytes(
407	KBUILD_MODNAME ": register: magic[raw]: ",
408	DUMP_PREFIX_NONE, e->magic, p - e->magic);
409
410	/* Parse the 'mask' field. */
411	e->mask = p;
412	p = scanarg(p, del);
413	if (!p)
414	goto einval;
415	if (!e->mask[0]) {
416	e->mask = NULL;
417	pr_debug("register: mask[raw]: none\n");
418	} else if (USE_DEBUG)
419	print_hex_dump_bytes(
420	KBUILD_MODNAME ": register: mask[raw]: ",
421	DUMP_PREFIX_NONE, e->mask, p - e->mask);
422
423	/*
424	* Decode the magic & mask fields.
425	* Note: while we might have accepted embedded NUL bytes from
426	* above, the unescape helpers here will stop at the first one
427	* it encounters.
428	*/
429	e->size = string_unescape_inplace(e->magic, UNESCAPE_HEX);
430	if (e->mask &&
431	string_unescape_inplace(e->mask, UNESCAPE_HEX) != e->size)
432	goto einval;
433	if (e->size > BINPRM_BUF_SIZE ||
434	BINPRM_BUF_SIZE - e->size < e->offset)
435	goto einval;
436	pr_debug("register: magic/mask length: %i\n", e->size);
437	if (USE_DEBUG) {
438	print_hex_dump_bytes(
439	KBUILD_MODNAME ": register: magic[decoded]: ",
440	DUMP_PREFIX_NONE, e->magic, e->size);
441
442	if (e->mask) {
443	int i;
444	char *masked = kmalloc(e->size, GFP_KERNEL);
445
446	print_hex_dump_bytes(
447	KBUILD_MODNAME ": register: mask[decoded]: ",
448	DUMP_PREFIX_NONE, e->mask, e->size);
449
450	if (masked) {
451	for (i = 0; i < e->size; ++i)
452	masked[i] = e->magic[i] & e->mask[i];
453	print_hex_dump_bytes(
454	KBUILD_MODNAME ": register: magic[masked]: ",
455	DUMP_PREFIX_NONE, masked, e->size);
456
457	kfree(masked);
458	}
459	}
460	}
461	} else {
462	/* Handle the 'E' (extension) format. */
463
464	/* Skip the 'offset' field. */
465	p = strchr(p, del);
466	if (!p)
467	goto einval;
468	*p++ = '\0';
469
470	/* Parse the 'magic' field. */
471	e->magic = p;
472	p = strchr(p, del);
473	if (!p)
474	goto einval;
475	*p++ = '\0';
476	if (!e->magic[0] || strchr(e->magic, '/'))
477	goto einval;
478	pr_debug("register: extension: {%s}\n", e->magic);
479
480	/* Skip the 'mask' field. */
481	p = strchr(p, del);
482	if (!p)
483	goto einval;
484	*p++ = '\0';
485	}
486
487	/* Parse the 'interpreter' field. */
488	e->interpreter = p;
489	p = strchr(p, del);
490	if (!p)
491	goto einval;
492	*p++ = '\0';
493	if (!e->interpreter[0])
494	goto einval;
495	pr_debug("register: interpreter: {%s}\n", e->interpreter);
496
497	/* Parse the 'flags' field. */
498	p = check_special_flags(p, e);
499	if (*p == '\n')
500	p++;
501	if (p != buf + count)
502	goto einval;
503
504	return e;
505
506	out:
507	return ERR_PTR(err);
508
509	efault:
510	kfree(e);
511	return ERR_PTR(-EFAULT);
512	einval:
513	kfree(e);
514	return ERR_PTR(-EINVAL);
515	}
516
517	/*
518	* Set status of entry/binfmt_misc:
519	* '1' enables, '0' disables and '-1' clears entry/binfmt_misc
520	*/
521	static int parse_command(const char __user *buffer, size_t count)
522	{
523	char s[4];
524
525	if (count > 3)
526	return -EINVAL;
527	if (copy_from_user(s, buffer, count))
528	return -EFAULT;
529	if (!count)
530	return 0;
531	if (s[count - 1] == '\n')
532	count--;
533	if (count == 1 && s[0] == '0')
534	return 1;
535	if (count == 1 && s[0] == '1')
536	return 2;
537	if (count == 2 && s[0] == '-' && s[1] == '1')
538	return 3;
539	return -EINVAL;
540	}
541
542	/* generic stuff */
543
544	static void entry_status(Node *e, char *page)
545	{
546	char *dp = page;
547	const char *status = "disabled";
548
549	if (test_bit(Enabled, &e->flags))
550	status = "enabled";
551
552	if (!VERBOSE_STATUS) {
553	sprintf(page, "%s\n", status);
554	return;
555	}
556
557	dp += sprintf(dp, "%s\ninterpreter %s\n", status, e->interpreter);
558
559	/* print the special flags */
560	dp += sprintf(dp, "flags: ");
561	if (e->flags & MISC_FMT_PRESERVE_ARGV0)
562	*dp++ = 'P';
563	if (e->flags & MISC_FMT_OPEN_BINARY)
564	*dp++ = 'O';
565	if (e->flags & MISC_FMT_CREDENTIALS)
566	*dp++ = 'C';
567	if (e->flags & MISC_FMT_OPEN_FILE)
568	*dp++ = 'F';
569	*dp++ = '\n';
570
571	if (!test_bit(Magic, &e->flags)) {
572	sprintf(dp, "extension .%s\n", e->magic);
573	} else {
574	dp += sprintf(dp, "offset %i\nmagic ", e->offset);
575	dp = bin2hex(dp, e->magic, e->size);
576	if (e->mask) {
577	dp += sprintf(dp, "\nmask ");
578	dp = bin2hex(dp, e->mask, e->size);
579	}
580	*dp++ = '\n';
581	*dp = '\0';
582	}
583	}
584
585	static struct inode *bm_get_inode(struct super_block *sb, int mode)
586	{
587	struct inode *inode = new_inode(sb);
588
589	if (inode) {
590	inode->i_ino = get_next_ino();
591	inode->i_mode = mode;
592	inode->i_atime = inode->i_mtime = inode->i_ctime =
593	current_time(inode);
594	}
595	return inode;
596	}
597
598	static void bm_evict_inode(struct inode *inode)
599	{
600	clear_inode(inode);
601	kfree(inode->i_private);
602	}
603
604	static void kill_node(Node *e)
605	{
606	struct dentry *dentry;
607
608	write_lock(&entries_lock);
609	dentry = e->dentry;
610	if (dentry) {
611	list_del_init(&e->list);
612	e->dentry = NULL;
613	}
614	write_unlock(&entries_lock);
615
616	if ((e->flags & MISC_FMT_OPEN_FILE) && e->interp_file) {
617	filp_close(e->interp_file, NULL);
618	e->interp_file = NULL;
619	}
620
621	if (dentry) {
622	drop_nlink(d_inode(dentry));
623	d_drop(dentry);
624	dput(dentry);
625	simple_release_fs(&bm_mnt, &entry_count);
626	}
627	}
628
629	/* /<entry> */
630
631	static ssize_t
632	bm_entry_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
633	{
634	Node *e = file_inode(file)->i_private;
635	ssize_t res;
636	char *page;
637
638	page = (char *) __get_free_page(GFP_KERNEL);
639	if (!page)
640	return -ENOMEM;
641
642	entry_status(e, page);
643
644	res = simple_read_from_buffer(buf, nbytes, ppos, page, strlen(page));
645
646	free_page((unsigned long) page);
647	return res;
648	}
649
650	static ssize_t bm_entry_write(struct file *file, const char __user *buffer,
651	size_t count, loff_t *ppos)
652	{
653	struct dentry *root;
654	Node *e = file_inode(file)->i_private;
655	int res = parse_command(buffer, count);
656
657	switch (res) {
658	case 1:
659	/* Disable this handler. */
660	clear_bit(Enabled, &e->flags);
661	break;
662	case 2:
663	/* Enable this handler. */
664	set_bit(Enabled, &e->flags);
665	break;
666	case 3:
667	/* Delete this handler. */
668	root = file_inode(file)->i_sb->s_root;
669	inode_lock(d_inode(root));
670
671	kill_node(e);
672
673	inode_unlock(d_inode(root));
674	break;
675	default:
676	return res;
677	}
678
679	return count;
680	}
681
682	static const struct file_operations bm_entry_operations = {
683	.read = bm_entry_read,
684	.write = bm_entry_write,
685	.llseek = default_llseek,
686	};
687
688	/* /register */
689
690	static ssize_t bm_register_write(struct file *file, const char __user *buffer,
691	size_t count, loff_t *ppos)
692	{
693	Node *e;
694	struct inode *inode;
695	struct super_block *sb = file_inode(file)->i_sb;
696	struct dentry *root = sb->s_root, *dentry;
697	int err = 0;
698
699	e = create_entry(buffer, count);
700
701	if (IS_ERR(e))
702	return PTR_ERR(e);
703
704	inode_lock(d_inode(root));
705	dentry = lookup_one_len(e->name, root, strlen(e->name));
706	err = PTR_ERR(dentry);
707	if (IS_ERR(dentry))
708	goto out;
709
710	err = -EEXIST;
711	if (d_really_is_positive(dentry))
712	goto out2;
713
714	inode = bm_get_inode(sb, S_IFREG | 0644);
715
716	err = -ENOMEM;
717	if (!inode)
718	goto out2;
719
720	err = simple_pin_fs(&bm_fs_type, &bm_mnt, &entry_count);
721	if (err) {
722	iput(inode);
723	inode = NULL;
724	goto out2;
725	}
726
727	if (e->flags & MISC_FMT_OPEN_FILE) {
728	struct file *f;
729
730	f = open_exec(e->interpreter);
731	if (IS_ERR(f)) {
732	err = PTR_ERR(f);
733	pr_notice("register: failed to install interpreter file %s\n", e->interpreter);
734	simple_release_fs(&bm_mnt, &entry_count);
735	iput(inode);
736	inode = NULL;
737	goto out2;
738	}
739	e->interp_file = f;
740	}
741
742	e->dentry = dget(dentry);
743	inode->i_private = e;
744	inode->i_fop = &bm_entry_operations;
745
746	d_instantiate(dentry, inode);
747	write_lock(&entries_lock);
748	list_add(&e->list, &entries);
749	write_unlock(&entries_lock);
750
751	err = 0;
752	out2:
753	dput(dentry);
754	out:
755	inode_unlock(d_inode(root));
756
757	if (err) {
758	kfree(e);
759	return err;
760	}
761	return count;
762	}
763
764	static const struct file_operations bm_register_operations = {
765	.write = bm_register_write,
766	.llseek = noop_llseek,
767	};
768
769	/* /status */
770
771	static ssize_t
772	bm_status_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
773	{
774	char *s = enabled ? "enabled\n" : "disabled\n";
775
776	return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s));
777	}
778
779	static ssize_t bm_status_write(struct file *file, const char __user *buffer,
780	size_t count, loff_t *ppos)
781	{
782	int res = parse_command(buffer, count);
783	struct dentry *root;
784
785	switch (res) {
786	case 1:
787	/* Disable all handlers. */
788	enabled = 0;
789	break;
790	case 2:
791	/* Enable all handlers. */
792	enabled = 1;
793	break;
794	case 3:
795	/* Delete all handlers. */
796	root = file_inode(file)->i_sb->s_root;
797	inode_lock(d_inode(root));
798
799	while (!list_empty(&entries))
800	kill_node(list_entry(entries.next, Node, list));
801
802	inode_unlock(d_inode(root));
803	break;
804	default:
805	return res;
806	}
807
808	return count;
809	}
810
811	static const struct file_operations bm_status_operations = {
812	.read = bm_status_read,
813	.write = bm_status_write,
814	.llseek = default_llseek,
815	};
816
817	/* Superblock handling */
818
819	static const struct super_operations s_ops = {
820	.statfs = simple_statfs,
821	.evict_inode = bm_evict_inode,
822	};
823
824	static int bm_fill_super(struct super_block *sb, void *data, int silent)
825	{
826	int err;
827	static struct tree_descr bm_files[] = {
828	[2] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
829	[3] = {"register", &bm_register_operations, S_IWUSR},
830	/* last one */ {""}
831	};
832
833	err = simple_fill_super(sb, BINFMTFS_MAGIC, bm_files);
834	if (!err)
835	sb->s_op = &s_ops;
836	return err;
837	}
838
839	static struct dentry *bm_mount(struct file_system_type *fs_type,
840	int flags, const char *dev_name, void *data)
841	{
842	return mount_single(fs_type, flags, data, bm_fill_super);
843	}
844
845	static struct linux_binfmt misc_format = {
846	.module = THIS_MODULE,
847	.load_binary = load_misc_binary,
848	};
849
850	static struct file_system_type bm_fs_type = {
851	.owner = THIS_MODULE,
852	.name = "binfmt_misc",
853	.mount = bm_mount,
854	.kill_sb = kill_litter_super,
855	};
856	MODULE_ALIAS_FS("binfmt_misc");
857
858	static int __init init_misc_binfmt(void)
859	{
860	int err = register_filesystem(&bm_fs_type);
861	if (!err)
862	insert_binfmt(&misc_format);
863	return err;
864	}
865
866	static void __exit exit_misc_binfmt(void)
867	{
868	unregister_binfmt(&misc_format);
869	unregister_filesystem(&bm_fs_type);
870	}
871
872	core_initcall(init_misc_binfmt);
873	module_exit(exit_misc_binfmt);
874	MODULE_LICENSE("GPL");
875