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