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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Daemon interface
3 *
4 * Copyright (C) 2007, 2021 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells ([email protected])
6 */
7
8#include <linux/module.h>
9#include <linux/init.h>
10#include <linux/sched.h>
11#include <linux/completion.h>
12#include <linux/slab.h>
13#include <linux/fs.h>
14#include <linux/file.h>
15#include <linux/namei.h>
16#include <linux/poll.h>
17#include <linux/mount.h>
18#include <linux/security.h>
19#include <linux/statfs.h>
20#include <linux/ctype.h>
21#include <linux/string.h>
22#include <linux/fs_struct.h>
23#include "internal.h"
24
25static int cachefiles_daemon_open(struct inode *, struct file *);
26static int cachefiles_daemon_release(struct inode *, struct file *);
27static ssize_t cachefiles_daemon_read(struct file *, char __user *, size_t,
28 loff_t *);
29static ssize_t cachefiles_daemon_write(struct file *, const char __user *,
30 size_t, loff_t *);
31static __poll_t cachefiles_daemon_poll(struct file *,
32 struct poll_table_struct *);
33static int cachefiles_daemon_frun(struct cachefiles_cache *, char *);
34static int cachefiles_daemon_fcull(struct cachefiles_cache *, char *);
35static int cachefiles_daemon_fstop(struct cachefiles_cache *, char *);
36static int cachefiles_daemon_brun(struct cachefiles_cache *, char *);
37static int cachefiles_daemon_bcull(struct cachefiles_cache *, char *);
38static int cachefiles_daemon_bstop(struct cachefiles_cache *, char *);
39static int cachefiles_daemon_cull(struct cachefiles_cache *, char *);
40static int cachefiles_daemon_debug(struct cachefiles_cache *, char *);
41static int cachefiles_daemon_dir(struct cachefiles_cache *, char *);
42static int cachefiles_daemon_inuse(struct cachefiles_cache *, char *);
43static int cachefiles_daemon_secctx(struct cachefiles_cache *, char *);
44static int cachefiles_daemon_tag(struct cachefiles_cache *, char *);
45static int cachefiles_daemon_bind(struct cachefiles_cache *, char *);
46static void cachefiles_daemon_unbind(struct cachefiles_cache *);
47
48static unsigned long cachefiles_open;
49
50const struct file_operations cachefiles_daemon_fops = {
51 .owner = THIS_MODULE,
52 .open = cachefiles_daemon_open,
53 .release = cachefiles_daemon_release,
54 .read = cachefiles_daemon_read,
55 .write = cachefiles_daemon_write,
56 .poll = cachefiles_daemon_poll,
57 .llseek = noop_llseek,
58};
59
60struct cachefiles_daemon_cmd {
61 char name[8];
62 int (*handler)(struct cachefiles_cache *cache, char *args);
63};
64
65static const struct cachefiles_daemon_cmd cachefiles_daemon_cmds[] = {
66 { "bind", cachefiles_daemon_bind },
67 { "brun", cachefiles_daemon_brun },
68 { "bcull", cachefiles_daemon_bcull },
69 { "bstop", cachefiles_daemon_bstop },
70 { "cull", cachefiles_daemon_cull },
71 { "debug", cachefiles_daemon_debug },
72 { "dir", cachefiles_daemon_dir },
73 { "frun", cachefiles_daemon_frun },
74 { "fcull", cachefiles_daemon_fcull },
75 { "fstop", cachefiles_daemon_fstop },
76 { "inuse", cachefiles_daemon_inuse },
77 { "secctx", cachefiles_daemon_secctx },
78 { "tag", cachefiles_daemon_tag },
79 { "", NULL }
80};
81
82
83/*
84 * Prepare a cache for caching.
85 */
86static int cachefiles_daemon_open(struct inode *inode, struct file *file)
87{
88 struct cachefiles_cache *cache;
89
90 _enter("");
91
92 /* only the superuser may do this */
93 if (!capable(CAP_SYS_ADMIN))
94 return -EPERM;
95
96 /* the cachefiles device may only be open once at a time */
97 if (xchg(&cachefiles_open, 1) == 1)
98 return -EBUSY;
99
100 /* allocate a cache record */
101 cache = kzalloc_obj(struct cachefiles_cache);
102 if (!cache) {
103 cachefiles_open = 0;
104 return -ENOMEM;
105 }
106
107 mutex_init(&cache->daemon_mutex);
108 init_waitqueue_head(&cache->daemon_pollwq);
109 INIT_LIST_HEAD(&cache->volumes);
110 INIT_LIST_HEAD(&cache->object_list);
111 spin_lock_init(&cache->object_list_lock);
112
113 /* set default caching limits
114 * - limit at 1% free space and/or free files
115 * - cull below 5% free space and/or free files
116 * - cease culling above 7% free space and/or free files
117 */
118 cache->frun_percent = 7;
119 cache->fcull_percent = 5;
120 cache->fstop_percent = 1;
121 cache->brun_percent = 7;
122 cache->bcull_percent = 5;
123 cache->bstop_percent = 1;
124
125 file->private_data = cache;
126 cache->cachefilesd = file;
127 return 0;
128}
129
130/*
131 * Release a cache.
132 */
133static int cachefiles_daemon_release(struct inode *inode, struct file *file)
134{
135 struct cachefiles_cache *cache = file->private_data;
136
137 _enter("");
138
139 ASSERT(cache);
140
141 set_bit(CACHEFILES_DEAD, &cache->flags);
142 cachefiles_daemon_unbind(cache);
143
144 /* clean up the control file interface */
145 cache->cachefilesd = NULL;
146 file->private_data = NULL;
147 cachefiles_open = 0;
148
149 kfree(cache);
150 _leave("");
151 return 0;
152}
153
154static ssize_t cachefiles_do_daemon_read(struct cachefiles_cache *cache,
155 char __user *_buffer, size_t buflen)
156{
157 unsigned long long b_released;
158 unsigned f_released;
159 char buffer[256];
160 int n;
161
162 /* check how much space the cache has */
163 cachefiles_has_space(cache, 0, 0, cachefiles_has_space_check);
164
165 /* summarise */
166 f_released = atomic_xchg(&cache->f_released, 0);
167 b_released = atomic_long_xchg(&cache->b_released, 0);
168 clear_bit(CACHEFILES_STATE_CHANGED, &cache->flags);
169
170 n = snprintf(buffer, sizeof(buffer),
171 "cull=%c"
172 " frun=%llx"
173 " fcull=%llx"
174 " fstop=%llx"
175 " brun=%llx"
176 " bcull=%llx"
177 " bstop=%llx"
178 " freleased=%x"
179 " breleased=%llx",
180 test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '0',
181 (unsigned long long) cache->frun,
182 (unsigned long long) cache->fcull,
183 (unsigned long long) cache->fstop,
184 (unsigned long long) cache->brun,
185 (unsigned long long) cache->bcull,
186 (unsigned long long) cache->bstop,
187 f_released,
188 b_released);
189
190 if (n > buflen)
191 return -EMSGSIZE;
192
193 if (copy_to_user(_buffer, buffer, n) != 0)
194 return -EFAULT;
195
196 return n;
197}
198
199/*
200 * Read the cache state.
201 */
202static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer,
203 size_t buflen, loff_t *pos)
204{
205 struct cachefiles_cache *cache = file->private_data;
206
207 //_enter(",,%zu,", buflen);
208
209 if (!test_bit(CACHEFILES_READY, &cache->flags))
210 return 0;
211
212 return cachefiles_do_daemon_read(cache, _buffer, buflen);
213}
214
215/*
216 * Take a command from cachefilesd, parse it and act on it.
217 */
218static ssize_t cachefiles_daemon_write(struct file *file,
219 const char __user *_data,
220 size_t datalen,
221 loff_t *pos)
222{
223 const struct cachefiles_daemon_cmd *cmd;
224 struct cachefiles_cache *cache = file->private_data;
225 ssize_t ret;
226 char *data, *args, *cp;
227
228 //_enter(",,%zu,", datalen);
229
230 ASSERT(cache);
231
232 if (test_bit(CACHEFILES_DEAD, &cache->flags))
233 return -EIO;
234
235 if (datalen > PAGE_SIZE - 1)
236 return -EOPNOTSUPP;
237
238 /* drag the command string into the kernel so we can parse it */
239 data = memdup_user_nul(_data, datalen);
240 if (IS_ERR(data))
241 return PTR_ERR(data);
242
243 ret = -EINVAL;
244 if (memchr(data, '\0', datalen))
245 goto error;
246
247 /* strip any newline */
248 cp = memchr(data, '\n', datalen);
249 if (cp) {
250 if (cp == data)
251 goto error;
252
253 *cp = '\0';
254 }
255
256 /* parse the command */
257 ret = -EOPNOTSUPP;
258
259 for (args = data; *args; args++)
260 if (isspace(*args))
261 break;
262 if (*args) {
263 if (args == data)
264 goto error;
265 *args = '\0';
266 args = skip_spaces(++args);
267 }
268
269 /* run the appropriate command handler */
270 for (cmd = cachefiles_daemon_cmds; cmd->name[0]; cmd++)
271 if (strcmp(cmd->name, data) == 0)
272 goto found_command;
273
274error:
275 kfree(data);
276 //_leave(" = %zd", ret);
277 return ret;
278
279found_command:
280 mutex_lock(&cache->daemon_mutex);
281
282 ret = -EIO;
283 if (!test_bit(CACHEFILES_DEAD, &cache->flags))
284 ret = cmd->handler(cache, args);
285
286 mutex_unlock(&cache->daemon_mutex);
287
288 if (ret == 0)
289 ret = datalen;
290 goto error;
291}
292
293/*
294 * Poll for culling state
295 * - use EPOLLOUT to indicate culling state
296 */
297static __poll_t cachefiles_daemon_poll(struct file *file,
298 struct poll_table_struct *poll)
299{
300 struct cachefiles_cache *cache = file->private_data;
301 __poll_t mask;
302
303 poll_wait(file, &cache->daemon_pollwq, poll);
304 mask = 0;
305
306 if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
307 mask |= EPOLLIN;
308
309 if (test_bit(CACHEFILES_CULLING, &cache->flags))
310 mask |= EPOLLOUT;
311
312 return mask;
313}
314
315/*
316 * Give a range error for cache space constraints
317 * - can be tail-called
318 */
319static int cachefiles_daemon_range_error(struct cachefiles_cache *cache,
320 char *args)
321{
322 pr_err("Free space limits must be in range 0%%<=stop<cull<run<100%%\n");
323
324 return -EINVAL;
325}
326
327/*
328 * Set the percentage of files at which to stop culling
329 * - command: "frun <N>%"
330 */
331static int cachefiles_daemon_frun(struct cachefiles_cache *cache, char *args)
332{
333 unsigned long frun;
334
335 _enter(",%s", args);
336
337 if (!*args)
338 return -EINVAL;
339
340 frun = simple_strtoul(args, &args, 10);
341 if (args[0] != '%' || args[1] != '\0')
342 return -EINVAL;
343
344 if (frun <= cache->fcull_percent || frun >= 100)
345 return cachefiles_daemon_range_error(cache, args);
346
347 cache->frun_percent = frun;
348 return 0;
349}
350
351/*
352 * Set the percentage of files at which to start culling
353 * - command: "fcull <N>%"
354 */
355static int cachefiles_daemon_fcull(struct cachefiles_cache *cache, char *args)
356{
357 unsigned long fcull;
358
359 _enter(",%s", args);
360
361 if (!*args)
362 return -EINVAL;
363
364 fcull = simple_strtoul(args, &args, 10);
365 if (args[0] != '%' || args[1] != '\0')
366 return -EINVAL;
367
368 if (fcull <= cache->fstop_percent || fcull >= cache->frun_percent)
369 return cachefiles_daemon_range_error(cache, args);
370
371 cache->fcull_percent = fcull;
372 return 0;
373}
374
375/*
376 * Set the percentage of files at which to stop allocating
377 * - command: "fstop <N>%"
378 */
379static int cachefiles_daemon_fstop(struct cachefiles_cache *cache, char *args)
380{
381 unsigned long fstop;
382
383 _enter(",%s", args);
384
385 if (!*args)
386 return -EINVAL;
387
388 fstop = simple_strtoul(args, &args, 10);
389 if (args[0] != '%' || args[1] != '\0')
390 return -EINVAL;
391
392 if (fstop >= cache->fcull_percent)
393 return cachefiles_daemon_range_error(cache, args);
394
395 cache->fstop_percent = fstop;
396 return 0;
397}
398
399/*
400 * Set the percentage of blocks at which to stop culling
401 * - command: "brun <N>%"
402 */
403static int cachefiles_daemon_brun(struct cachefiles_cache *cache, char *args)
404{
405 unsigned long brun;
406
407 _enter(",%s", args);
408
409 if (!*args)
410 return -EINVAL;
411
412 brun = simple_strtoul(args, &args, 10);
413 if (args[0] != '%' || args[1] != '\0')
414 return -EINVAL;
415
416 if (brun <= cache->bcull_percent || brun >= 100)
417 return cachefiles_daemon_range_error(cache, args);
418
419 cache->brun_percent = brun;
420 return 0;
421}
422
423/*
424 * Set the percentage of blocks at which to start culling
425 * - command: "bcull <N>%"
426 */
427static int cachefiles_daemon_bcull(struct cachefiles_cache *cache, char *args)
428{
429 unsigned long bcull;
430
431 _enter(",%s", args);
432
433 if (!*args)
434 return -EINVAL;
435
436 bcull = simple_strtoul(args, &args, 10);
437 if (args[0] != '%' || args[1] != '\0')
438 return -EINVAL;
439
440 if (bcull <= cache->bstop_percent || bcull >= cache->brun_percent)
441 return cachefiles_daemon_range_error(cache, args);
442
443 cache->bcull_percent = bcull;
444 return 0;
445}
446
447/*
448 * Set the percentage of blocks at which to stop allocating
449 * - command: "bstop <N>%"
450 */
451static int cachefiles_daemon_bstop(struct cachefiles_cache *cache, char *args)
452{
453 unsigned long bstop;
454
455 _enter(",%s", args);
456
457 if (!*args)
458 return -EINVAL;
459
460 bstop = simple_strtoul(args, &args, 10);
461 if (args[0] != '%' || args[1] != '\0')
462 return -EINVAL;
463
464 if (bstop >= cache->bcull_percent)
465 return cachefiles_daemon_range_error(cache, args);
466
467 cache->bstop_percent = bstop;
468 return 0;
469}
470
471/*
472 * Set the cache directory
473 * - command: "dir <name>"
474 */
475static int cachefiles_daemon_dir(struct cachefiles_cache *cache, char *args)
476{
477 char *dir;
478
479 _enter(",%s", args);
480
481 if (!*args) {
482 pr_err("Empty directory specified\n");
483 return -EINVAL;
484 }
485
486 if (cache->rootdirname) {
487 pr_err("Second cache directory specified\n");
488 return -EEXIST;
489 }
490
491 dir = kstrdup(args, GFP_KERNEL);
492 if (!dir)
493 return -ENOMEM;
494
495 cache->rootdirname = dir;
496 return 0;
497}
498
499/*
500 * Set the cache security context
501 * - command: "secctx <ctx>"
502 */
503static int cachefiles_daemon_secctx(struct cachefiles_cache *cache, char *args)
504{
505 int err;
506
507 _enter(",%s", args);
508
509 if (!*args) {
510 pr_err("Empty security context specified\n");
511 return -EINVAL;
512 }
513
514 if (cache->have_secid) {
515 pr_err("Second security context specified\n");
516 return -EINVAL;
517 }
518
519 err = security_secctx_to_secid(args, strlen(args), &cache->secid);
520 if (err)
521 return err;
522
523 cache->have_secid = true;
524 return 0;
525}
526
527/*
528 * Set the cache tag
529 * - command: "tag <name>"
530 */
531static int cachefiles_daemon_tag(struct cachefiles_cache *cache, char *args)
532{
533 char *tag;
534
535 _enter(",%s", args);
536
537 if (!*args) {
538 pr_err("Empty tag specified\n");
539 return -EINVAL;
540 }
541
542 if (cache->tag)
543 return -EEXIST;
544
545 tag = kstrdup(args, GFP_KERNEL);
546 if (!tag)
547 return -ENOMEM;
548
549 cache->tag = tag;
550 return 0;
551}
552
553/*
554 * Request a node in the cache be culled from the current working directory
555 * - command: "cull <name>"
556 */
557static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args)
558{
559 struct path path;
560 const struct cred *saved_cred;
561 int ret;
562
563 _enter(",%s", args);
564
565 if (strchr(args, '/'))
566 goto inval;
567
568 if (!test_bit(CACHEFILES_READY, &cache->flags)) {
569 pr_err("cull applied to unready cache\n");
570 return -EIO;
571 }
572
573 if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
574 pr_err("cull applied to dead cache\n");
575 return -EIO;
576 }
577
578 get_fs_pwd(current->fs, &path);
579
580 if (!d_can_lookup(path.dentry))
581 goto notdir;
582
583 cachefiles_begin_secure(cache, &saved_cred);
584 ret = cachefiles_cull(cache, path.dentry, args);
585 cachefiles_end_secure(cache, saved_cred);
586
587 path_put(&path);
588 _leave(" = %d", ret);
589 return ret;
590
591notdir:
592 path_put(&path);
593 pr_err("cull command requires dirfd to be a directory\n");
594 return -ENOTDIR;
595
596inval:
597 pr_err("cull command requires dirfd and filename\n");
598 return -EINVAL;
599}
600
601/*
602 * Set debugging mode
603 * - command: "debug <mask>"
604 */
605static int cachefiles_daemon_debug(struct cachefiles_cache *cache, char *args)
606{
607 unsigned long mask;
608
609 _enter(",%s", args);
610
611 mask = simple_strtoul(args, &args, 0);
612 if (args[0] != '\0')
613 goto inval;
614
615 cachefiles_debug = mask;
616 _leave(" = 0");
617 return 0;
618
619inval:
620 pr_err("debug command requires mask\n");
621 return -EINVAL;
622}
623
624/*
625 * Find out whether an object in the current working directory is in use or not
626 * - command: "inuse <name>"
627 */
628static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args)
629{
630 struct path path;
631 const struct cred *saved_cred;
632 int ret;
633
634 //_enter(",%s", args);
635
636 if (strchr(args, '/'))
637 goto inval;
638
639 if (!test_bit(CACHEFILES_READY, &cache->flags)) {
640 pr_err("inuse applied to unready cache\n");
641 return -EIO;
642 }
643
644 if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
645 pr_err("inuse applied to dead cache\n");
646 return -EIO;
647 }
648
649 get_fs_pwd(current->fs, &path);
650
651 if (!d_can_lookup(path.dentry))
652 goto notdir;
653
654 cachefiles_begin_secure(cache, &saved_cred);
655 ret = cachefiles_check_in_use(cache, path.dentry, args);
656 cachefiles_end_secure(cache, saved_cred);
657
658 path_put(&path);
659 //_leave(" = %d", ret);
660 return ret;
661
662notdir:
663 path_put(&path);
664 pr_err("inuse command requires dirfd to be a directory\n");
665 return -ENOTDIR;
666
667inval:
668 pr_err("inuse command requires dirfd and filename\n");
669 return -EINVAL;
670}
671
672/*
673 * Bind a directory as a cache
674 */
675static int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args)
676{
677 _enter("{%u,%u,%u,%u,%u,%u},%s",
678 cache->frun_percent,
679 cache->fcull_percent,
680 cache->fstop_percent,
681 cache->brun_percent,
682 cache->bcull_percent,
683 cache->bstop_percent,
684 args);
685
686 if (cache->fstop_percent >= cache->fcull_percent ||
687 cache->fcull_percent >= cache->frun_percent ||
688 cache->frun_percent >= 100)
689 return -ERANGE;
690
691 if (cache->bstop_percent >= cache->bcull_percent ||
692 cache->bcull_percent >= cache->brun_percent ||
693 cache->brun_percent >= 100)
694 return -ERANGE;
695
696 if (!cache->rootdirname) {
697 pr_err("No cache directory specified\n");
698 return -EINVAL;
699 }
700
701 /* Don't permit already bound caches to be re-bound */
702 if (test_bit(CACHEFILES_READY, &cache->flags)) {
703 pr_err("Cache already bound\n");
704 return -EBUSY;
705 }
706
707 if (*args) {
708 pr_err("'bind' command doesn't take an argument\n");
709 return -EINVAL;
710 }
711
712 /* Make sure we have copies of the tag string */
713 if (!cache->tag) {
714 /*
715 * The tag string is released by the fops->release()
716 * function, so we don't release it on error here
717 */
718 cache->tag = kstrdup("CacheFiles", GFP_KERNEL);
719 if (!cache->tag)
720 return -ENOMEM;
721 }
722
723 return cachefiles_add_cache(cache);
724}
725
726/*
727 * Unbind a cache.
728 */
729static void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
730{
731 _enter("");
732
733 if (test_bit(CACHEFILES_READY, &cache->flags))
734 cachefiles_withdraw_cache(cache);
735
736 cachefiles_put_directory(cache->graveyard);
737 cachefiles_put_directory(cache->store);
738 mntput(cache->mnt);
739 put_cred(cache->cache_cred);
740
741 kfree(cache->rootdirname);
742 kfree(cache->tag);
743
744 _leave("");
745}