1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * binfmt_misc.c
4 *
5 * Copyright (C) 1997 Richard Günther
6 *
7 * binfmt_misc detects binaries via a magic or filename extension and invokes
8 * a specified wrapper. See Documentation/admin-guide/binfmt-misc.rst for more details.
9 */
10
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/sched/mm.h>
17 #include <linux/magic.h>
18 #include <linux/binfmts.h>
19 #include <linux/slab.h>
20 #include <linux/ctype.h>
21 #include <linux/string_helpers.h>
22 #include <linux/file.h>
23 #include <linux/pagemap.h>
24 #include <linux/namei.h>
25 #include <linux/mount.h>
26 #include <linux/fs_context.h>
27 #include <linux/syscalls.h>
28 #include <linux/fs.h>
29 #include <linux/uaccess.h>
30
31 #include "internal.h"
32
33 #ifdef DEBUG
34 # define USE_DEBUG 1
35 #else
36 # define USE_DEBUG 0
37 #endif
38
39 enum {
40 VERBOSE_STATUS = 1 /* make it zero to save 400 bytes kernel memory */
41 };
42
43 static LIST_HEAD(entries);
44 static int enabled = 1;
45
46 enum {Enabled, Magic};
47 #define MISC_FMT_PRESERVE_ARGV0 (1 << 31)
48 #define MISC_FMT_OPEN_BINARY (1 << 30)
49 #define MISC_FMT_CREDENTIALS (1 << 29)
50 #define MISC_FMT_OPEN_FILE (1 << 28)
51
52 typedef struct {
53 struct list_head list;
54 unsigned long flags; /* type, status, etc. */
55 int offset; /* offset of magic */
56 int size; /* size of magic/mask */
57 char *magic; /* magic or filename extension */
58 char *mask; /* mask, NULL for exact match */
59 const char *interpreter; /* filename of interpreter */
60 char *name;
61 struct dentry *dentry;
62 struct file *interp_file;
63 } Node;
64
65 static DEFINE_RWLOCK(entries_lock);
66 static struct file_system_type bm_fs_type;
67 static struct vfsmount *bm_mnt;
68 static int entry_count;
69
70 /*
71 * Max length of the register string. Determined by:
72 * - 7 delimiters
73 * - name: ~50 bytes
74 * - type: 1 byte
75 * - offset: 3 bytes (has to be smaller than BINPRM_BUF_SIZE)
76 * - magic: 128 bytes (512 in escaped form)
77 * - mask: 128 bytes (512 in escaped form)
78 * - interp: ~50 bytes
79 * - flags: 5 bytes
80 * Round that up a bit, and then back off to hold the internal data
81 * (like struct Node).
82 */
83 #define MAX_REGISTER_LENGTH 1920
84
85 /*
86 * Check if we support the binfmt
87 * if we do, return the node, else NULL
88 * locking is done in load_misc_binary
89 */
check_file(struct linux_binprm * bprm)90 static Node *check_file(struct linux_binprm *bprm)
91 {
92 char *p = strrchr(bprm->interp, '.');
93 struct list_head *l;
94
95 /* Walk all the registered handlers. */
96 list_for_each(l, &entries) {
97 Node *e = list_entry(l, Node, list);
98 char *s;
99 int j;
100
101 /* Make sure this one is currently enabled. */
102 if (!test_bit(Enabled, &e->flags))
103 continue;
104
105 /* Do matching based on extension if applicable. */
106 if (!test_bit(Magic, &e->flags)) {
107 if (p && !strcmp(e->magic, p + 1))
108 return e;
109 continue;
110 }
111
112 /* Do matching based on magic & mask. */
113 s = bprm->buf + e->offset;
114 if (e->mask) {
115 for (j = 0; j < e->size; j++)
116 if ((*s++ ^ e->magic[j]) & e->mask[j])
117 break;
118 } else {
119 for (j = 0; j < e->size; j++)
120 if ((*s++ ^ e->magic[j]))
121 break;
122 }
123 if (j == e->size)
124 return e;
125 }
126 return NULL;
127 }
128
129 /*
130 * the loader itself
131 */
load_misc_binary(struct linux_binprm * bprm)132 static int load_misc_binary(struct linux_binprm *bprm)
133 {
134 Node *fmt;
135 struct file *interp_file = NULL;
136 int retval;
137 int fd_binary = -1;
138
139 retval = -ENOEXEC;
140 if (!enabled)
141 return retval;
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 dget(fmt->dentry);
148 read_unlock(&entries_lock);
149 if (!fmt)
150 return retval;
151
152 /* Need to be able to load the file after exec */
153 retval = -ENOENT;
154 if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE)
155 goto ret;
156
157 if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) {
158 retval = remove_arg_zero(bprm);
159 if (retval)
160 goto ret;
161 }
162
163 if (fmt->flags & MISC_FMT_OPEN_BINARY) {
164
165 /* if the binary should be opened on behalf of the
166 * interpreter than keep it open and assign descriptor
167 * to it
168 */
169 fd_binary = get_unused_fd_flags(0);
170 if (fd_binary < 0) {
171 retval = fd_binary;
172 goto ret;
173 }
174 fd_install(fd_binary, bprm->file);
175
176 /* if the binary is not readable than enforce mm->dumpable=0
177 regardless of the interpreter's permissions */
178 would_dump(bprm, bprm->file);
179
180 allow_write_access(bprm->file);
181 bprm->file = NULL;
182
183 /* mark the bprm that fd should be passed to interp */
184 bprm->interp_flags |= BINPRM_FLAGS_EXECFD;
185 bprm->interp_data = fd_binary;
186
187 } else {
188 allow_write_access(bprm->file);
189 fput(bprm->file);
190 bprm->file = NULL;
191 }
192 /* make argv[1] be the path to the binary */
193 retval = copy_strings_kernel(1, &bprm->interp, bprm);
194 if (retval < 0)
195 goto error;
196 bprm->argc++;
197
198 /* add the interp as argv[0] */
199 retval = copy_strings_kernel(1, &fmt->interpreter, bprm);
200 if (retval < 0)
201 goto error;
202 bprm->argc++;
203
204 /* Update interp in case binfmt_script needs it. */
205 retval = bprm_change_interp(fmt->interpreter, bprm);
206 if (retval < 0)
207 goto error;
208
209 if (fmt->flags & MISC_FMT_OPEN_FILE) {
210 interp_file = file_clone_open(fmt->interp_file);
211 if (!IS_ERR(interp_file))
212 deny_write_access(interp_file);
213 } else {
214 interp_file = open_exec(fmt->interpreter);
215 }
216 retval = PTR_ERR(interp_file);
217 if (IS_ERR(interp_file))
218 goto error;
219
220 bprm->file = interp_file;
221 if (fmt->flags & MISC_FMT_CREDENTIALS) {
222 loff_t pos = 0;
223
224 /*
225 * No need to call prepare_binprm(), it's already been
226 * done. bprm->buf is stale, update from interp_file.
227 */
228 memset(bprm->buf, 0, BINPRM_BUF_SIZE);
229 retval = kernel_read(bprm->file, bprm->buf, BINPRM_BUF_SIZE,
230 &pos);
231 } else
232 retval = prepare_binprm(bprm);
233
234 if (retval < 0)
235 goto error;
236
237 retval = search_binary_handler(bprm);
238 if (retval < 0)
239 goto error;
240
241 ret:
242 dput(fmt->dentry);
243 return retval;
244 error:
245 if (fd_binary > 0)
246 ksys_close(fd_binary);
247 bprm->interp_flags = 0;
248 bprm->interp_data = 0;
249 goto ret;
250 }
251
252 /* Command parsers */
253
254 /*
255 * parses and copies one argument enclosed in del from *sp to *dp,
256 * recognising the \x special.
257 * returns pointer to the copied argument or NULL in case of an
258 * error (and sets err) or null argument length.
259 */
scanarg(char * s,char del)260 static char *scanarg(char *s, char del)
261 {
262 char c;
263
264 while ((c = *s++) != del) {
265 if (c == '\\' && *s == 'x') {
266 s++;
267 if (!isxdigit(*s++))
268 return NULL;
269 if (!isxdigit(*s++))
270 return NULL;
271 }
272 }
273 s[-1] ='\0';
274 return s;
275 }
276
check_special_flags(char * sfs,Node * e)277 static char *check_special_flags(char *sfs, Node *e)
278 {
279 char *p = sfs;
280 int cont = 1;
281
282 /* special flags */
283 while (cont) {
284 switch (*p) {
285 case 'P':
286 pr_debug("register: flag: P (preserve argv0)\n");
287 p++;
288 e->flags |= MISC_FMT_PRESERVE_ARGV0;
289 break;
290 case 'O':
291 pr_debug("register: flag: O (open binary)\n");
292 p++;
293 e->flags |= MISC_FMT_OPEN_BINARY;
294 break;
295 case 'C':
296 pr_debug("register: flag: C (preserve creds)\n");
297 p++;
298 /* this flags also implies the
299 open-binary flag */
300 e->flags |= (MISC_FMT_CREDENTIALS |
301 MISC_FMT_OPEN_BINARY);
302 break;
303 case 'F':
304 pr_debug("register: flag: F: open interpreter file now\n");
305 p++;
306 e->flags |= MISC_FMT_OPEN_FILE;
307 break;
308 default:
309 cont = 0;
310 }
311 }
312
313 return p;
314 }
315
316 /*
317 * This registers a new binary format, it recognises the syntax
318 * ':name:type:offset:magic:mask:interpreter:flags'
319 * where the ':' is the IFS, that can be chosen with the first char
320 */
create_entry(const char __user * buffer,size_t count)321 static Node *create_entry(const char __user *buffer, size_t count)
322 {
323 Node *e;
324 int memsize, err;
325 char *buf, *p;
326 char del;
327
328 pr_debug("register: received %zu bytes\n", count);
329
330 /* some sanity checks */
331 err = -EINVAL;
332 if ((count < 11) || (count > MAX_REGISTER_LENGTH))
333 goto out;
334
335 err = -ENOMEM;
336 memsize = sizeof(Node) + count + 8;
337 e = kmalloc(memsize, GFP_KERNEL);
338 if (!e)
339 goto out;
340
341 p = buf = (char *)e + sizeof(Node);
342
343 memset(e, 0, sizeof(Node));
344 if (copy_from_user(buf, buffer, count))
345 goto efault;
346
347 del = *p++; /* delimeter */
348
349 pr_debug("register: delim: %#x {%c}\n", del, del);
350
351 /* Pad the buffer with the delim to simplify parsing below. */
352 memset(buf + count, del, 8);
353
354 /* Parse the 'name' field. */
355 e->name = p;
356 p = strchr(p, del);
357 if (!p)
358 goto einval;
359 *p++ = '\0';
360 if (!e->name[0] ||
361 !strcmp(e->name, ".") ||
362 !strcmp(e->name, "..") ||
363 strchr(e->name, '/'))
364 goto einval;
365
366 pr_debug("register: name: {%s}\n", e->name);
367
368 /* Parse the 'type' field. */
369 switch (*p++) {
370 case 'E':
371 pr_debug("register: type: E (extension)\n");
372 e->flags = 1 << Enabled;
373 break;
374 case 'M':
375 pr_debug("register: type: M (magic)\n");
376 e->flags = (1 << Enabled) | (1 << Magic);
377 break;
378 default:
379 goto einval;
380 }
381 if (*p++ != del)
382 goto einval;
383
384 if (test_bit(Magic, &e->flags)) {
385 /* Handle the 'M' (magic) format. */
386 char *s;
387
388 /* Parse the 'offset' field. */
389 s = strchr(p, del);
390 if (!s)
391 goto einval;
392 *s = '\0';
393 if (p != s) {
394 int r = kstrtoint(p, 10, &e->offset);
395 if (r != 0 || e->offset < 0)
396 goto einval;
397 }
398 p = s;
399 if (*p++)
400 goto einval;
401 pr_debug("register: offset: %#x\n", e->offset);
402
403 /* Parse the 'magic' field. */
404 e->magic = p;
405 p = scanarg(p, del);
406 if (!p)
407 goto einval;
408 if (!e->magic[0])
409 goto einval;
410 if (USE_DEBUG)
411 print_hex_dump_bytes(
412 KBUILD_MODNAME ": register: magic[raw]: ",
413 DUMP_PREFIX_NONE, e->magic, p - e->magic);
414
415 /* Parse the 'mask' field. */
416 e->mask = p;
417 p = scanarg(p, del);
418 if (!p)
419 goto einval;
420 if (!e->mask[0]) {
421 e->mask = NULL;
422 pr_debug("register: mask[raw]: none\n");
423 } else if (USE_DEBUG)
424 print_hex_dump_bytes(
425 KBUILD_MODNAME ": register: mask[raw]: ",
426 DUMP_PREFIX_NONE, e->mask, p - e->mask);
427
428 /*
429 * Decode the magic & mask fields.
430 * Note: while we might have accepted embedded NUL bytes from
431 * above, the unescape helpers here will stop at the first one
432 * it encounters.
433 */
434 e->size = string_unescape_inplace(e->magic, UNESCAPE_HEX);
435 if (e->mask &&
436 string_unescape_inplace(e->mask, UNESCAPE_HEX) != e->size)
437 goto einval;
438 if (e->size > BINPRM_BUF_SIZE ||
439 BINPRM_BUF_SIZE - e->size < e->offset)
440 goto einval;
441 pr_debug("register: magic/mask length: %i\n", e->size);
442 if (USE_DEBUG) {
443 print_hex_dump_bytes(
444 KBUILD_MODNAME ": register: magic[decoded]: ",
445 DUMP_PREFIX_NONE, e->magic, e->size);
446
447 if (e->mask) {
448 int i;
449 char *masked = kmalloc(e->size, GFP_KERNEL);
450
451 print_hex_dump_bytes(
452 KBUILD_MODNAME ": register: mask[decoded]: ",
453 DUMP_PREFIX_NONE, e->mask, e->size);
454
455 if (masked) {
456 for (i = 0; i < e->size; ++i)
457 masked[i] = e->magic[i] & e->mask[i];
458 print_hex_dump_bytes(
459 KBUILD_MODNAME ": register: magic[masked]: ",
460 DUMP_PREFIX_NONE, masked, e->size);
461
462 kfree(masked);
463 }
464 }
465 }
466 } else {
467 /* Handle the 'E' (extension) format. */
468
469 /* Skip the 'offset' field. */
470 p = strchr(p, del);
471 if (!p)
472 goto einval;
473 *p++ = '\0';
474
475 /* Parse the 'magic' field. */
476 e->magic = p;
477 p = strchr(p, del);
478 if (!p)
479 goto einval;
480 *p++ = '\0';
481 if (!e->magic[0] || strchr(e->magic, '/'))
482 goto einval;
483 pr_debug("register: extension: {%s}\n", e->magic);
484
485 /* Skip the 'mask' field. */
486 p = strchr(p, del);
487 if (!p)
488 goto einval;
489 *p++ = '\0';
490 }
491
492 /* Parse the 'interpreter' field. */
493 e->interpreter = p;
494 p = strchr(p, del);
495 if (!p)
496 goto einval;
497 *p++ = '\0';
498 if (!e->interpreter[0])
499 goto einval;
500 pr_debug("register: interpreter: {%s}\n", e->interpreter);
501
502 /* Parse the 'flags' field. */
503 p = check_special_flags(p, e);
504 if (*p == '\n')
505 p++;
506 if (p != buf + count)
507 goto einval;
508
509 return e;
510
511 out:
512 return ERR_PTR(err);
513
514 efault:
515 kfree(e);
516 return ERR_PTR(-EFAULT);
517 einval:
518 kfree(e);
519 return ERR_PTR(-EINVAL);
520 }
521
522 /*
523 * Set status of entry/binfmt_misc:
524 * '1' enables, '0' disables and '-1' clears entry/binfmt_misc
525 */
parse_command(const char __user * buffer,size_t count)526 static int parse_command(const char __user *buffer, size_t count)
527 {
528 char s[4];
529
530 if (count > 3)
531 return -EINVAL;
532 if (copy_from_user(s, buffer, count))
533 return -EFAULT;
534 if (!count)
535 return 0;
536 if (s[count - 1] == '\n')
537 count--;
538 if (count == 1 && s[0] == '0')
539 return 1;
540 if (count == 1 && s[0] == '1')
541 return 2;
542 if (count == 2 && s[0] == '-' && s[1] == '1')
543 return 3;
544 return -EINVAL;
545 }
546
547 /* generic stuff */
548
entry_status(Node * e,char * page)549 static void entry_status(Node *e, char *page)
550 {
551 char *dp = page;
552 const char *status = "disabled";
553
554 if (test_bit(Enabled, &e->flags))
555 status = "enabled";
556
557 if (!VERBOSE_STATUS) {
558 sprintf(page, "%s\n", status);
559 return;
560 }
561
562 dp += sprintf(dp, "%s\ninterpreter %s\n", status, e->interpreter);
563
564 /* print the special flags */
565 dp += sprintf(dp, "flags: ");
566 if (e->flags & MISC_FMT_PRESERVE_ARGV0)
567 *dp++ = 'P';
568 if (e->flags & MISC_FMT_OPEN_BINARY)
569 *dp++ = 'O';
570 if (e->flags & MISC_FMT_CREDENTIALS)
571 *dp++ = 'C';
572 if (e->flags & MISC_FMT_OPEN_FILE)
573 *dp++ = 'F';
574 *dp++ = '\n';
575
576 if (!test_bit(Magic, &e->flags)) {
577 sprintf(dp, "extension .%s\n", e->magic);
578 } else {
579 dp += sprintf(dp, "offset %i\nmagic ", e->offset);
580 dp = bin2hex(dp, e->magic, e->size);
581 if (e->mask) {
582 dp += sprintf(dp, "\nmask ");
583 dp = bin2hex(dp, e->mask, e->size);
584 }
585 *dp++ = '\n';
586 *dp = '\0';
587 }
588 }
589
bm_get_inode(struct super_block * sb,int mode)590 static struct inode *bm_get_inode(struct super_block *sb, int mode)
591 {
592 struct inode *inode = new_inode(sb);
593
594 if (inode) {
595 inode->i_ino = get_next_ino();
596 inode->i_mode = mode;
597 inode->i_atime = inode->i_mtime = inode->i_ctime =
598 current_time(inode);
599 }
600 return inode;
601 }
602
bm_evict_inode(struct inode * inode)603 static void bm_evict_inode(struct inode *inode)
604 {
605 Node *e = inode->i_private;
606
607 if (e && e->flags & MISC_FMT_OPEN_FILE)
608 filp_close(e->interp_file, NULL);
609
610 clear_inode(inode);
611 kfree(e);
612 }
613
kill_node(Node * e)614 static void kill_node(Node *e)
615 {
616 struct dentry *dentry;
617
618 write_lock(&entries_lock);
619 list_del_init(&e->list);
620 write_unlock(&entries_lock);
621
622 dentry = e->dentry;
623 drop_nlink(d_inode(dentry));
624 d_drop(dentry);
625 dput(dentry);
626 simple_release_fs(&bm_mnt, &entry_count);
627 }
628
629 /* /<entry> */
630
631 static ssize_t
bm_entry_read(struct file * file,char __user * buf,size_t nbytes,loff_t * ppos)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
bm_entry_write(struct file * file,const char __user * buffer,size_t count,loff_t * ppos)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 if (!list_empty(&e->list))
672 kill_node(e);
673
674 inode_unlock(d_inode(root));
675 break;
676 default:
677 return res;
678 }
679
680 return count;
681 }
682
683 static const struct file_operations bm_entry_operations = {
684 .read = bm_entry_read,
685 .write = bm_entry_write,
686 .llseek = default_llseek,
687 };
688
689 /* /register */
690
bm_register_write(struct file * file,const char __user * buffer,size_t count,loff_t * ppos)691 static ssize_t bm_register_write(struct file *file, const char __user *buffer,
692 size_t count, loff_t *ppos)
693 {
694 Node *e;
695 struct inode *inode;
696 struct super_block *sb = file_inode(file)->i_sb;
697 struct dentry *root = sb->s_root, *dentry;
698 int err = 0;
699
700 e = create_entry(buffer, count);
701
702 if (IS_ERR(e))
703 return PTR_ERR(e);
704
705 inode_lock(d_inode(root));
706 dentry = lookup_one_len(e->name, root, strlen(e->name));
707 err = PTR_ERR(dentry);
708 if (IS_ERR(dentry))
709 goto out;
710
711 err = -EEXIST;
712 if (d_really_is_positive(dentry))
713 goto out2;
714
715 inode = bm_get_inode(sb, S_IFREG | 0644);
716
717 err = -ENOMEM;
718 if (!inode)
719 goto out2;
720
721 err = simple_pin_fs(&bm_fs_type, &bm_mnt, &entry_count);
722 if (err) {
723 iput(inode);
724 inode = NULL;
725 goto out2;
726 }
727
728 if (e->flags & MISC_FMT_OPEN_FILE) {
729 struct file *f;
730
731 f = open_exec(e->interpreter);
732 if (IS_ERR(f)) {
733 err = PTR_ERR(f);
734 pr_notice("register: failed to install interpreter file %s\n", e->interpreter);
735 simple_release_fs(&bm_mnt, &entry_count);
736 iput(inode);
737 inode = NULL;
738 goto out2;
739 }
740 e->interp_file = f;
741 }
742
743 e->dentry = dget(dentry);
744 inode->i_private = e;
745 inode->i_fop = &bm_entry_operations;
746
747 d_instantiate(dentry, inode);
748 write_lock(&entries_lock);
749 list_add(&e->list, &entries);
750 write_unlock(&entries_lock);
751
752 err = 0;
753 out2:
754 dput(dentry);
755 out:
756 inode_unlock(d_inode(root));
757
758 if (err) {
759 kfree(e);
760 return err;
761 }
762 return count;
763 }
764
765 static const struct file_operations bm_register_operations = {
766 .write = bm_register_write,
767 .llseek = noop_llseek,
768 };
769
770 /* /status */
771
772 static ssize_t
bm_status_read(struct file * file,char __user * buf,size_t nbytes,loff_t * ppos)773 bm_status_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
774 {
775 char *s = enabled ? "enabled\n" : "disabled\n";
776
777 return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s));
778 }
779
bm_status_write(struct file * file,const char __user * buffer,size_t count,loff_t * ppos)780 static ssize_t bm_status_write(struct file *file, const char __user *buffer,
781 size_t count, loff_t *ppos)
782 {
783 int res = parse_command(buffer, count);
784 struct dentry *root;
785
786 switch (res) {
787 case 1:
788 /* Disable all handlers. */
789 enabled = 0;
790 break;
791 case 2:
792 /* Enable all handlers. */
793 enabled = 1;
794 break;
795 case 3:
796 /* Delete all handlers. */
797 root = file_inode(file)->i_sb->s_root;
798 inode_lock(d_inode(root));
799
800 while (!list_empty(&entries))
801 kill_node(list_first_entry(&entries, Node, list));
802
803 inode_unlock(d_inode(root));
804 break;
805 default:
806 return res;
807 }
808
809 return count;
810 }
811
812 static const struct file_operations bm_status_operations = {
813 .read = bm_status_read,
814 .write = bm_status_write,
815 .llseek = default_llseek,
816 };
817
818 /* Superblock handling */
819
820 static const struct super_operations s_ops = {
821 .statfs = simple_statfs,
822 .evict_inode = bm_evict_inode,
823 };
824
bm_fill_super(struct super_block * sb,struct fs_context * fc)825 static int bm_fill_super(struct super_block *sb, struct fs_context *fc)
826 {
827 int err;
828 static const struct tree_descr bm_files[] = {
829 [2] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO},
830 [3] = {"register", &bm_register_operations, S_IWUSR},
831 /* last one */ {""}
832 };
833
834 err = simple_fill_super(sb, BINFMTFS_MAGIC, bm_files);
835 if (!err)
836 sb->s_op = &s_ops;
837 return err;
838 }
839
bm_get_tree(struct fs_context * fc)840 static int bm_get_tree(struct fs_context *fc)
841 {
842 return get_tree_single(fc, bm_fill_super);
843 }
844
845 static const struct fs_context_operations bm_context_ops = {
846 .get_tree = bm_get_tree,
847 };
848
bm_init_fs_context(struct fs_context * fc)849 static int bm_init_fs_context(struct fs_context *fc)
850 {
851 fc->ops = &bm_context_ops;
852 return 0;
853 }
854
855 static struct linux_binfmt misc_format = {
856 .module = THIS_MODULE,
857 .load_binary = load_misc_binary,
858 };
859
860 static struct file_system_type bm_fs_type = {
861 .owner = THIS_MODULE,
862 .name = "binfmt_misc",
863 .init_fs_context = bm_init_fs_context,
864 .kill_sb = kill_litter_super,
865 };
866 MODULE_ALIAS_FS("binfmt_misc");
867
init_misc_binfmt(void)868 static int __init init_misc_binfmt(void)
869 {
870 int err = register_filesystem(&bm_fs_type);
871 if (!err)
872 insert_binfmt(&misc_format);
873 return err;
874 }
875
exit_misc_binfmt(void)876 static void __exit exit_misc_binfmt(void)
877 {
878 unregister_binfmt(&misc_format);
879 unregister_filesystem(&bm_fs_type);
880 }
881
882 core_initcall(init_misc_binfmt);
883 module_exit(exit_misc_binfmt);
884 MODULE_LICENSE("GPL");
885