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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/module.h> | |
13 | #include <linux/init.h> | |
14 | #include <linux/sched.h> | |
15 | #include <linux/magic.h> | |
16 | #include <linux/binfmts.h> | |
17 | #include <linux/slab.h> | |
18 | #include <linux/ctype.h> | |
19 | #include <linux/string_helpers.h> | |
20 | #include <linux/file.h> | |
21 | #include <linux/pagemap.h> | |
22 | #include <linux/namei.h> | |
23 | #include <linux/mount.h> | |
24 | #include <linux/syscalls.h> | |
25 | #include <linux/fs.h> | |
26 | #include <linux/uaccess.h> | |
27 | ||
28 | #ifdef DEBUG | |
29 | # define USE_DEBUG 1 | |
30 | #else | |
31 | # define USE_DEBUG 0 | |
32 | #endif | |
33 | ||
34 | enum { | |
35 | VERBOSE_STATUS = 1 /* make it zero to save 400 bytes kernel memory */ | |
36 | }; | |
37 | ||
38 | static LIST_HEAD(entries); | |
39 | static int enabled = 1; | |
40 | ||
41 | enum {Enabled, Magic}; | |
42 | #define MISC_FMT_PRESERVE_ARGV0 (1 << 31) | |
43 | #define MISC_FMT_OPEN_BINARY (1 << 30) | |
44 | #define MISC_FMT_CREDENTIALS (1 << 29) | |
45 | ||
46 | typedef struct { | |
47 | struct list_head list; | |
48 | unsigned long flags; /* type, status, etc. */ | |
49 | int offset; /* offset of magic */ | |
50 | int size; /* size of magic/mask */ | |
51 | char *magic; /* magic or filename extension */ | |
52 | char *mask; /* mask, NULL for exact match */ | |
53 | char *interpreter; /* filename of interpreter */ | |
54 | char *name; | |
55 | struct dentry *dentry; | |
56 | } Node; | |
57 | ||
58 | static DEFINE_RWLOCK(entries_lock); | |
59 | static struct file_system_type bm_fs_type; | |
60 | static struct vfsmount *bm_mnt; | |
61 | static int entry_count; | |
62 | ||
63 | /* | |
64 | * Max length of the register string. Determined by: | |
65 | * - 7 delimiters | |
66 | * - name: ~50 bytes | |
67 | * - type: 1 byte | |
68 | * - offset: 3 bytes (has to be smaller than BINPRM_BUF_SIZE) | |
69 | * - magic: 128 bytes (512 in escaped form) | |
70 | * - mask: 128 bytes (512 in escaped form) | |
71 | * - interp: ~50 bytes | |
72 | * - flags: 5 bytes | |
73 | * Round that up a bit, and then back off to hold the internal data | |
74 | * (like struct Node). | |
75 | */ | |
76 | #define MAX_REGISTER_LENGTH 1920 | |
77 | ||
78 | /* | |
79 | * Check if we support the binfmt | |
80 | * if we do, return the node, else NULL | |
81 | * locking is done in load_misc_binary | |
82 | */ | |
83 | static Node *check_file(struct linux_binprm *bprm) | |
84 | { | |
85 | char *p = strrchr(bprm->interp, '.'); | |
86 | struct list_head *l; | |
87 | ||
88 | /* Walk all the registered handlers. */ | |
89 | list_for_each(l, &entries) { | |
90 | Node *e = list_entry(l, Node, list); | |
91 | char *s; | |
92 | int j; | |
93 | ||
94 | /* Make sure this one is currently enabled. */ | |
95 | if (!test_bit(Enabled, &e->flags)) | |
96 | continue; | |
97 | ||
98 | /* Do matching based on extension if applicable. */ | |
99 | if (!test_bit(Magic, &e->flags)) { | |
100 | if (p && !strcmp(e->magic, p + 1)) | |
101 | return e; | |
102 | continue; | |
103 | } | |
104 | ||
105 | /* Do matching based on magic & mask. */ | |
106 | s = bprm->buf + e->offset; | |
107 | if (e->mask) { | |
108 | for (j = 0; j < e->size; j++) | |
109 | if ((*s++ ^ e->magic[j]) & e->mask[j]) | |
110 | break; | |
111 | } else { | |
112 | for (j = 0; j < e->size; j++) | |
113 | if ((*s++ ^ e->magic[j])) | |
114 | break; | |
115 | } | |
116 | if (j == e->size) | |
117 | return e; | |
118 | } | |
119 | return NULL; | |
120 | } | |
121 | ||
122 | /* | |
123 | * the loader itself | |
124 | */ | |
125 | static int load_misc_binary(struct linux_binprm *bprm) | |
126 | { | |
127 | Node *fmt; | |
128 | struct file *interp_file = NULL; | |
129 | char iname[BINPRM_BUF_SIZE]; | |
130 | const char *iname_addr = iname; | |
131 | int retval; | |
132 | int fd_binary = -1; | |
133 | ||
134 | retval = -ENOEXEC; | |
135 | if (!enabled) | |
136 | goto ret; | |
137 | ||
138 | /* to keep locking time low, we copy the interpreter string */ | |
139 | read_lock(&entries_lock); | |
140 | fmt = check_file(bprm); | |
141 | if (fmt) | |
142 | strlcpy(iname, fmt->interpreter, BINPRM_BUF_SIZE); | |
143 | read_unlock(&entries_lock); | |
144 | if (!fmt) | |
145 | goto ret; | |
146 | ||
147 | /* Need to be able to load the file after exec */ | |
148 | if (bprm->interp_flags & BINPRM_FLAGS_PATH_INACCESSIBLE) | |
149 | return -ENOENT; | |
150 | ||
151 | if (!(fmt->flags & MISC_FMT_PRESERVE_ARGV0)) { | |
152 | retval = remove_arg_zero(bprm); | |
153 | if (retval) | |
154 | goto ret; | |
155 | } | |
156 | ||
157 | if (fmt->flags & MISC_FMT_OPEN_BINARY) { | |
158 | ||
159 | /* if the binary should be opened on behalf of the | |
160 | * interpreter than keep it open and assign descriptor | |
161 | * to it | |
162 | */ | |
163 | fd_binary = get_unused_fd_flags(0); | |
164 | if (fd_binary < 0) { | |
165 | retval = fd_binary; | |
166 | goto ret; | |
167 | } | |
168 | fd_install(fd_binary, bprm->file); | |
169 | ||
170 | /* if the binary is not readable than enforce mm->dumpable=0 | |
171 | regardless of the interpreter's permissions */ | |
172 | would_dump(bprm, bprm->file); | |
173 | ||
174 | allow_write_access(bprm->file); | |
175 | bprm->file = NULL; | |
176 | ||
177 | /* mark the bprm that fd should be passed to interp */ | |
178 | bprm->interp_flags |= BINPRM_FLAGS_EXECFD; | |
179 | bprm->interp_data = fd_binary; | |
180 | ||
181 | } else { | |
182 | allow_write_access(bprm->file); | |
183 | fput(bprm->file); | |
184 | bprm->file = NULL; | |
185 | } | |
186 | /* make argv[1] be the path to the binary */ | |
187 | retval = copy_strings_kernel(1, &bprm->interp, bprm); | |
188 | if (retval < 0) | |
189 | goto error; | |
190 | bprm->argc++; | |
191 | ||
192 | /* add the interp as argv[0] */ | |
193 | retval = copy_strings_kernel(1, &iname_addr, bprm); | |
194 | if (retval < 0) | |
195 | goto error; | |
196 | bprm->argc++; | |
197 | ||
198 | /* Update interp in case binfmt_script needs it. */ | |
199 | retval = bprm_change_interp(iname, bprm); | |
200 | if (retval < 0) | |
201 | goto error; | |
202 | ||
203 | interp_file = open_exec(iname); | |
204 | retval = PTR_ERR(interp_file); | |
205 | if (IS_ERR(interp_file)) | |
206 | goto error; | |
207 | ||
208 | bprm->file = interp_file; | |
209 | if (fmt->flags & MISC_FMT_CREDENTIALS) { | |
210 | /* | |
211 | * No need to call prepare_binprm(), it's already been | |
212 | * done. bprm->buf is stale, update from interp_file. | |
213 | */ | |
214 | memset(bprm->buf, 0, BINPRM_BUF_SIZE); | |
215 | retval = kernel_read(bprm->file, 0, bprm->buf, BINPRM_BUF_SIZE); | |
216 | } else | |
217 | retval = prepare_binprm(bprm); | |
218 | ||
219 | if (retval < 0) | |
220 | goto error; | |
221 | ||
222 | retval = search_binary_handler(bprm); | |
223 | if (retval < 0) | |
224 | goto error; | |
225 | ||
226 | ret: | |
227 | return retval; | |
228 | error: | |
229 | if (fd_binary > 0) | |
230 | sys_close(fd_binary); | |
231 | bprm->interp_flags = 0; | |
232 | bprm->interp_data = 0; | |
233 | goto ret; | |
234 | } | |
235 | ||
236 | /* Command parsers */ | |
237 | ||
238 | /* | |
239 | * parses and copies one argument enclosed in del from *sp to *dp, | |
240 | * recognising the \x special. | |
241 | * returns pointer to the copied argument or NULL in case of an | |
242 | * error (and sets err) or null argument length. | |
243 | */ | |
244 | static char *scanarg(char *s, char del) | |
245 | { | |
246 | char c; | |
247 | ||
248 | while ((c = *s++) != del) { | |
249 | if (c == '\\' && *s == 'x') { | |
250 | s++; | |
251 | if (!isxdigit(*s++)) | |
252 | return NULL; | |
253 | if (!isxdigit(*s++)) | |
254 | return NULL; | |
255 | } | |
256 | } | |
257 | s[-1] ='\0'; | |
258 | return s; | |
259 | } | |
260 | ||
261 | static char *check_special_flags(char *sfs, Node *e) | |
262 | { | |
263 | char *p = sfs; | |
264 | int cont = 1; | |
265 | ||
266 | /* special flags */ | |
267 | while (cont) { | |
268 | switch (*p) { | |
269 | case 'P': | |
270 | pr_debug("register: flag: P (preserve argv0)\n"); | |
271 | p++; | |
272 | e->flags |= MISC_FMT_PRESERVE_ARGV0; | |
273 | break; | |
274 | case 'O': | |
275 | pr_debug("register: flag: O (open binary)\n"); | |
276 | p++; | |
277 | e->flags |= MISC_FMT_OPEN_BINARY; | |
278 | break; | |
279 | case 'C': | |
280 | pr_debug("register: flag: C (preserve creds)\n"); | |
281 | p++; | |
282 | /* this flags also implies the | |
283 | open-binary flag */ | |
284 | e->flags |= (MISC_FMT_CREDENTIALS | | |
285 | MISC_FMT_OPEN_BINARY); | |
286 | break; | |
287 | default: | |
288 | cont = 0; | |
289 | } | |
290 | } | |
291 | ||
292 | return p; | |
293 | } | |
294 | ||
295 | /* | |
296 | * This registers a new binary format, it recognises the syntax | |
297 | * ':name:type:offset:magic:mask:interpreter:flags' | |
298 | * where the ':' is the IFS, that can be chosen with the first char | |
299 | */ | |
300 | static Node *create_entry(const char __user *buffer, size_t count) | |
301 | { | |
302 | Node *e; | |
303 | int memsize, err; | |
304 | char *buf, *p; | |
305 | char del; | |
306 | ||
307 | pr_debug("register: received %zu bytes\n", count); | |
308 | ||
309 | /* some sanity checks */ | |
310 | err = -EINVAL; | |
311 | if ((count < 11) || (count > MAX_REGISTER_LENGTH)) | |
312 | goto out; | |
313 | ||
314 | err = -ENOMEM; | |
315 | memsize = sizeof(Node) + count + 8; | |
316 | e = kmalloc(memsize, GFP_KERNEL); | |
317 | if (!e) | |
318 | goto out; | |
319 | ||
320 | p = buf = (char *)e + sizeof(Node); | |
321 | ||
322 | memset(e, 0, sizeof(Node)); | |
323 | if (copy_from_user(buf, buffer, count)) | |
324 | goto efault; | |
325 | ||
326 | del = *p++; /* delimeter */ | |
327 | ||
328 | pr_debug("register: delim: %#x {%c}\n", del, del); | |
329 | ||
330 | /* Pad the buffer with the delim to simplify parsing below. */ | |
331 | memset(buf + count, del, 8); | |
332 | ||
333 | /* Parse the 'name' field. */ | |
334 | e->name = p; | |
335 | p = strchr(p, del); | |
336 | if (!p) | |
337 | goto einval; | |
338 | *p++ = '\0'; | |
339 | if (!e->name[0] || | |
340 | !strcmp(e->name, ".") || | |
341 | !strcmp(e->name, "..") || | |
342 | strchr(e->name, '/')) | |
343 | goto einval; | |
344 | ||
345 | pr_debug("register: name: {%s}\n", e->name); | |
346 | ||
347 | /* Parse the 'type' field. */ | |
348 | switch (*p++) { | |
349 | case 'E': | |
350 | pr_debug("register: type: E (extension)\n"); | |
351 | e->flags = 1 << Enabled; | |
352 | break; | |
353 | case 'M': | |
354 | pr_debug("register: type: M (magic)\n"); | |
355 | e->flags = (1 << Enabled) | (1 << Magic); | |
356 | break; | |
357 | default: | |
358 | goto einval; | |
359 | } | |
360 | if (*p++ != del) | |
361 | goto einval; | |
362 | ||
363 | if (test_bit(Magic, &e->flags)) { | |
364 | /* Handle the 'M' (magic) format. */ | |
365 | char *s; | |
366 | ||
367 | /* Parse the 'offset' field. */ | |
368 | s = strchr(p, del); | |
369 | if (!s) | |
370 | goto einval; | |
371 | *s++ = '\0'; | |
372 | e->offset = simple_strtoul(p, &p, 10); | |
373 | if (*p++) | |
374 | goto einval; | |
375 | pr_debug("register: offset: %#x\n", e->offset); | |
376 | ||
377 | /* Parse the 'magic' field. */ | |
378 | e->magic = p; | |
379 | p = scanarg(p, del); | |
380 | if (!p) | |
381 | goto einval; | |
382 | if (!e->magic[0]) | |
383 | goto einval; | |
384 | if (USE_DEBUG) | |
385 | print_hex_dump_bytes( | |
386 | KBUILD_MODNAME ": register: magic[raw]: ", | |
387 | DUMP_PREFIX_NONE, e->magic, p - e->magic); | |
388 | ||
389 | /* Parse the 'mask' field. */ | |
390 | e->mask = p; | |
391 | p = scanarg(p, del); | |
392 | if (!p) | |
393 | goto einval; | |
394 | if (!e->mask[0]) { | |
395 | e->mask = NULL; | |
396 | pr_debug("register: mask[raw]: none\n"); | |
397 | } else if (USE_DEBUG) | |
398 | print_hex_dump_bytes( | |
399 | KBUILD_MODNAME ": register: mask[raw]: ", | |
400 | DUMP_PREFIX_NONE, e->mask, p - e->mask); | |
401 | ||
402 | /* | |
403 | * Decode the magic & mask fields. | |
404 | * Note: while we might have accepted embedded NUL bytes from | |
405 | * above, the unescape helpers here will stop at the first one | |
406 | * it encounters. | |
407 | */ | |
408 | e->size = string_unescape_inplace(e->magic, UNESCAPE_HEX); | |
409 | if (e->mask && | |
410 | string_unescape_inplace(e->mask, UNESCAPE_HEX) != e->size) | |
411 | goto einval; | |
412 | if (e->size + e->offset > BINPRM_BUF_SIZE) | |
413 | goto einval; | |
414 | pr_debug("register: magic/mask length: %i\n", e->size); | |
415 | if (USE_DEBUG) { | |
416 | print_hex_dump_bytes( | |
417 | KBUILD_MODNAME ": register: magic[decoded]: ", | |
418 | DUMP_PREFIX_NONE, e->magic, e->size); | |
419 | ||
420 | if (e->mask) { | |
421 | int i; | |
422 | char *masked = kmalloc(e->size, GFP_KERNEL); | |
423 | ||
424 | print_hex_dump_bytes( | |
425 | KBUILD_MODNAME ": register: mask[decoded]: ", | |
426 | DUMP_PREFIX_NONE, e->mask, e->size); | |
427 | ||
428 | if (masked) { | |
429 | for (i = 0; i < e->size; ++i) | |
430 | masked[i] = e->magic[i] & e->mask[i]; | |
431 | print_hex_dump_bytes( | |
432 | KBUILD_MODNAME ": register: magic[masked]: ", | |
433 | DUMP_PREFIX_NONE, masked, e->size); | |
434 | ||
435 | kfree(masked); | |
436 | } | |
437 | } | |
438 | } | |
439 | } else { | |
440 | /* Handle the 'E' (extension) format. */ | |
441 | ||
442 | /* Skip the 'offset' field. */ | |
443 | p = strchr(p, del); | |
444 | if (!p) | |
445 | goto einval; | |
446 | *p++ = '\0'; | |
447 | ||
448 | /* Parse the 'magic' field. */ | |
449 | e->magic = p; | |
450 | p = strchr(p, del); | |
451 | if (!p) | |
452 | goto einval; | |
453 | *p++ = '\0'; | |
454 | if (!e->magic[0] || strchr(e->magic, '/')) | |
455 | goto einval; | |
456 | pr_debug("register: extension: {%s}\n", e->magic); | |
457 | ||
458 | /* Skip the 'mask' field. */ | |
459 | p = strchr(p, del); | |
460 | if (!p) | |
461 | goto einval; | |
462 | *p++ = '\0'; | |
463 | } | |
464 | ||
465 | /* Parse the 'interpreter' field. */ | |
466 | e->interpreter = p; | |
467 | p = strchr(p, del); | |
468 | if (!p) | |
469 | goto einval; | |
470 | *p++ = '\0'; | |
471 | if (!e->interpreter[0]) | |
472 | goto einval; | |
473 | pr_debug("register: interpreter: {%s}\n", e->interpreter); | |
474 | ||
475 | /* Parse the 'flags' field. */ | |
476 | p = check_special_flags(p, e); | |
477 | if (*p == '\n') | |
478 | p++; | |
479 | if (p != buf + count) | |
480 | goto einval; | |
481 | ||
482 | return e; | |
483 | ||
484 | out: | |
485 | return ERR_PTR(err); | |
486 | ||
487 | efault: | |
488 | kfree(e); | |
489 | return ERR_PTR(-EFAULT); | |
490 | einval: | |
491 | kfree(e); | |
492 | return ERR_PTR(-EINVAL); | |
493 | } | |
494 | ||
495 | /* | |
496 | * Set status of entry/binfmt_misc: | |
497 | * '1' enables, '0' disables and '-1' clears entry/binfmt_misc | |
498 | */ | |
499 | static int parse_command(const char __user *buffer, size_t count) | |
500 | { | |
501 | char s[4]; | |
502 | ||
503 | if (count > 3) | |
504 | return -EINVAL; | |
505 | if (copy_from_user(s, buffer, count)) | |
506 | return -EFAULT; | |
507 | if (!count) | |
508 | return 0; | |
509 | if (s[count - 1] == '\n') | |
510 | count--; | |
511 | if (count == 1 && s[0] == '0') | |
512 | return 1; | |
513 | if (count == 1 && s[0] == '1') | |
514 | return 2; | |
515 | if (count == 2 && s[0] == '-' && s[1] == '1') | |
516 | return 3; | |
517 | return -EINVAL; | |
518 | } | |
519 | ||
520 | /* generic stuff */ | |
521 | ||
522 | static void entry_status(Node *e, char *page) | |
523 | { | |
524 | char *dp; | |
525 | char *status = "disabled"; | |
526 | const char *flags = "flags: "; | |
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 | sprintf(page, "%s\ninterpreter %s\n", status, e->interpreter); | |
537 | dp = page + strlen(page); | |
538 | ||
539 | /* print the special flags */ | |
540 | sprintf(dp, "%s", flags); | |
541 | dp += strlen(flags); | |
542 | if (e->flags & MISC_FMT_PRESERVE_ARGV0) | |
543 | *dp++ = 'P'; | |
544 | if (e->flags & MISC_FMT_OPEN_BINARY) | |
545 | *dp++ = 'O'; | |
546 | if (e->flags & MISC_FMT_CREDENTIALS) | |
547 | *dp++ = 'C'; | |
548 | *dp++ = '\n'; | |
549 | ||
550 | if (!test_bit(Magic, &e->flags)) { | |
551 | sprintf(dp, "extension .%s\n", e->magic); | |
552 | } else { | |
553 | int i; | |
554 | ||
555 | sprintf(dp, "offset %i\nmagic ", e->offset); | |
556 | dp = page + strlen(page); | |
557 | for (i = 0; i < e->size; i++) { | |
558 | sprintf(dp, "%02x", 0xff & (int) (e->magic[i])); | |
559 | dp += 2; | |
560 | } | |
561 | if (e->mask) { | |
562 | sprintf(dp, "\nmask "); | |
563 | dp += 6; | |
564 | for (i = 0; i < e->size; i++) { | |
565 | sprintf(dp, "%02x", 0xff & (int) (e->mask[i])); | |
566 | dp += 2; | |
567 | } | |
568 | } | |
569 | *dp++ = '\n'; | |
570 | *dp = '\0'; | |
571 | } | |
572 | } | |
573 | ||
574 | static struct inode *bm_get_inode(struct super_block *sb, int mode) | |
575 | { | |
576 | struct inode *inode = new_inode(sb); | |
577 | ||
578 | if (inode) { | |
579 | inode->i_ino = get_next_ino(); | |
580 | inode->i_mode = mode; | |
581 | inode->i_atime = inode->i_mtime = inode->i_ctime = | |
582 | current_fs_time(inode->i_sb); | |
583 | } | |
584 | return inode; | |
585 | } | |
586 | ||
587 | static void bm_evict_inode(struct inode *inode) | |
588 | { | |
589 | clear_inode(inode); | |
590 | kfree(inode->i_private); | |
591 | } | |
592 | ||
593 | static void kill_node(Node *e) | |
594 | { | |
595 | struct dentry *dentry; | |
596 | ||
597 | write_lock(&entries_lock); | |
598 | dentry = e->dentry; | |
599 | if (dentry) { | |
600 | list_del_init(&e->list); | |
601 | e->dentry = NULL; | |
602 | } | |
603 | write_unlock(&entries_lock); | |
604 | ||
605 | if (dentry) { | |
606 | drop_nlink(dentry->d_inode); | |
607 | d_drop(dentry); | |
608 | dput(dentry); | |
609 | simple_release_fs(&bm_mnt, &entry_count); | |
610 | } | |
611 | } | |
612 | ||
613 | /* /<entry> */ | |
614 | ||
615 | static ssize_t | |
616 | bm_entry_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) | |
617 | { | |
618 | Node *e = file_inode(file)->i_private; | |
619 | ssize_t res; | |
620 | char *page; | |
621 | ||
622 | page = (char *) __get_free_page(GFP_KERNEL); | |
623 | if (!page) | |
624 | return -ENOMEM; | |
625 | ||
626 | entry_status(e, page); | |
627 | ||
628 | res = simple_read_from_buffer(buf, nbytes, ppos, page, strlen(page)); | |
629 | ||
630 | free_page((unsigned long) page); | |
631 | return res; | |
632 | } | |
633 | ||
634 | static ssize_t bm_entry_write(struct file *file, const char __user *buffer, | |
635 | size_t count, loff_t *ppos) | |
636 | { | |
637 | struct dentry *root; | |
638 | Node *e = file_inode(file)->i_private; | |
639 | int res = parse_command(buffer, count); | |
640 | ||
641 | switch (res) { | |
642 | case 1: | |
643 | /* Disable this handler. */ | |
644 | clear_bit(Enabled, &e->flags); | |
645 | break; | |
646 | case 2: | |
647 | /* Enable this handler. */ | |
648 | set_bit(Enabled, &e->flags); | |
649 | break; | |
650 | case 3: | |
651 | /* Delete this handler. */ | |
652 | root = dget(file->f_path.dentry->d_sb->s_root); | |
653 | mutex_lock(&root->d_inode->i_mutex); | |
654 | ||
655 | kill_node(e); | |
656 | ||
657 | mutex_unlock(&root->d_inode->i_mutex); | |
658 | dput(root); | |
659 | break; | |
660 | default: | |
661 | return res; | |
662 | } | |
663 | ||
664 | return count; | |
665 | } | |
666 | ||
667 | static const struct file_operations bm_entry_operations = { | |
668 | .read = bm_entry_read, | |
669 | .write = bm_entry_write, | |
670 | .llseek = default_llseek, | |
671 | }; | |
672 | ||
673 | /* /register */ | |
674 | ||
675 | static ssize_t bm_register_write(struct file *file, const char __user *buffer, | |
676 | size_t count, loff_t *ppos) | |
677 | { | |
678 | Node *e; | |
679 | struct inode *inode; | |
680 | struct dentry *root, *dentry; | |
681 | struct super_block *sb = file->f_path.dentry->d_sb; | |
682 | int err = 0; | |
683 | ||
684 | e = create_entry(buffer, count); | |
685 | ||
686 | if (IS_ERR(e)) | |
687 | return PTR_ERR(e); | |
688 | ||
689 | root = dget(sb->s_root); | |
690 | mutex_lock(&root->d_inode->i_mutex); | |
691 | dentry = lookup_one_len(e->name, root, strlen(e->name)); | |
692 | err = PTR_ERR(dentry); | |
693 | if (IS_ERR(dentry)) | |
694 | goto out; | |
695 | ||
696 | err = -EEXIST; | |
697 | if (dentry->d_inode) | |
698 | goto out2; | |
699 | ||
700 | inode = bm_get_inode(sb, S_IFREG | 0644); | |
701 | ||
702 | err = -ENOMEM; | |
703 | if (!inode) | |
704 | goto out2; | |
705 | ||
706 | err = simple_pin_fs(&bm_fs_type, &bm_mnt, &entry_count); | |
707 | if (err) { | |
708 | iput(inode); | |
709 | inode = NULL; | |
710 | goto out2; | |
711 | } | |
712 | ||
713 | e->dentry = dget(dentry); | |
714 | inode->i_private = e; | |
715 | inode->i_fop = &bm_entry_operations; | |
716 | ||
717 | d_instantiate(dentry, inode); | |
718 | write_lock(&entries_lock); | |
719 | list_add(&e->list, &entries); | |
720 | write_unlock(&entries_lock); | |
721 | ||
722 | err = 0; | |
723 | out2: | |
724 | dput(dentry); | |
725 | out: | |
726 | mutex_unlock(&root->d_inode->i_mutex); | |
727 | dput(root); | |
728 | ||
729 | if (err) { | |
730 | kfree(e); | |
731 | return -EINVAL; | |
732 | } | |
733 | return count; | |
734 | } | |
735 | ||
736 | static const struct file_operations bm_register_operations = { | |
737 | .write = bm_register_write, | |
738 | .llseek = noop_llseek, | |
739 | }; | |
740 | ||
741 | /* /status */ | |
742 | ||
743 | static ssize_t | |
744 | bm_status_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) | |
745 | { | |
746 | char *s = enabled ? "enabled\n" : "disabled\n"; | |
747 | ||
748 | return simple_read_from_buffer(buf, nbytes, ppos, s, strlen(s)); | |
749 | } | |
750 | ||
751 | static ssize_t bm_status_write(struct file *file, const char __user *buffer, | |
752 | size_t count, loff_t *ppos) | |
753 | { | |
754 | int res = parse_command(buffer, count); | |
755 | struct dentry *root; | |
756 | ||
757 | switch (res) { | |
758 | case 1: | |
759 | /* Disable all handlers. */ | |
760 | enabled = 0; | |
761 | break; | |
762 | case 2: | |
763 | /* Enable all handlers. */ | |
764 | enabled = 1; | |
765 | break; | |
766 | case 3: | |
767 | /* Delete all handlers. */ | |
768 | root = dget(file->f_path.dentry->d_sb->s_root); | |
769 | mutex_lock(&root->d_inode->i_mutex); | |
770 | ||
771 | while (!list_empty(&entries)) | |
772 | kill_node(list_entry(entries.next, Node, list)); | |
773 | ||
774 | mutex_unlock(&root->d_inode->i_mutex); | |
775 | dput(root); | |
776 | break; | |
777 | default: | |
778 | return res; | |
779 | } | |
780 | ||
781 | return count; | |
782 | } | |
783 | ||
784 | static const struct file_operations bm_status_operations = { | |
785 | .read = bm_status_read, | |
786 | .write = bm_status_write, | |
787 | .llseek = default_llseek, | |
788 | }; | |
789 | ||
790 | /* Superblock handling */ | |
791 | ||
792 | static const struct super_operations s_ops = { | |
793 | .statfs = simple_statfs, | |
794 | .evict_inode = bm_evict_inode, | |
795 | }; | |
796 | ||
797 | static int bm_fill_super(struct super_block *sb, void *data, int silent) | |
798 | { | |
799 | int err; | |
800 | static struct tree_descr bm_files[] = { | |
801 | [2] = {"status", &bm_status_operations, S_IWUSR|S_IRUGO}, | |
802 | [3] = {"register", &bm_register_operations, S_IWUSR}, | |
803 | /* last one */ {""} | |
804 | }; | |
805 | ||
806 | err = simple_fill_super(sb, BINFMTFS_MAGIC, bm_files); | |
807 | if (!err) | |
808 | sb->s_op = &s_ops; | |
809 | return err; | |
810 | } | |
811 | ||
812 | static struct dentry *bm_mount(struct file_system_type *fs_type, | |
813 | int flags, const char *dev_name, void *data) | |
814 | { | |
815 | return mount_single(fs_type, flags, data, bm_fill_super); | |
816 | } | |
817 | ||
818 | static struct linux_binfmt misc_format = { | |
819 | .module = THIS_MODULE, | |
820 | .load_binary = load_misc_binary, | |
821 | }; | |
822 | ||
823 | static struct file_system_type bm_fs_type = { | |
824 | .owner = THIS_MODULE, | |
825 | .name = "binfmt_misc", | |
826 | .mount = bm_mount, | |
827 | .kill_sb = kill_litter_super, | |
828 | }; | |
829 | MODULE_ALIAS_FS("binfmt_misc"); | |
830 | ||
831 | static int __init init_misc_binfmt(void) | |
832 | { | |
833 | int err = register_filesystem(&bm_fs_type); | |
834 | if (!err) | |
835 | insert_binfmt(&misc_format); | |
836 | return err; | |
837 | } | |
838 | ||
839 | static void __exit exit_misc_binfmt(void) | |
840 | { | |
841 | unregister_binfmt(&misc_format); | |
842 | unregister_filesystem(&bm_fs_type); | |
843 | } | |
844 | ||
845 | core_initcall(init_misc_binfmt); | |
846 | module_exit(exit_misc_binfmt); | |
847 | MODULE_LICENSE("GPL"); |