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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Daemon interface
3 *
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
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/statfs.h>
19#include <linux/ctype.h>
20#include <linux/string.h>
21#include <linux/fs_struct.h>
22#include "internal.h"
23
24static int cachefiles_daemon_open(struct inode *, struct file *);
25static int cachefiles_daemon_release(struct inode *, struct file *);
26static ssize_t cachefiles_daemon_read(struct file *, char __user *, size_t,
27 loff_t *);
28static ssize_t cachefiles_daemon_write(struct file *, const char __user *,
29 size_t, loff_t *);
30static __poll_t cachefiles_daemon_poll(struct file *,
31 struct poll_table_struct *);
32static int cachefiles_daemon_frun(struct cachefiles_cache *, char *);
33static int cachefiles_daemon_fcull(struct cachefiles_cache *, char *);
34static int cachefiles_daemon_fstop(struct cachefiles_cache *, char *);
35static int cachefiles_daemon_brun(struct cachefiles_cache *, char *);
36static int cachefiles_daemon_bcull(struct cachefiles_cache *, char *);
37static int cachefiles_daemon_bstop(struct cachefiles_cache *, char *);
38static int cachefiles_daemon_cull(struct cachefiles_cache *, char *);
39static int cachefiles_daemon_debug(struct cachefiles_cache *, char *);
40static int cachefiles_daemon_dir(struct cachefiles_cache *, char *);
41static int cachefiles_daemon_inuse(struct cachefiles_cache *, char *);
42static int cachefiles_daemon_secctx(struct cachefiles_cache *, char *);
43static int cachefiles_daemon_tag(struct cachefiles_cache *, char *);
44
45static unsigned long cachefiles_open;
46
47const struct file_operations cachefiles_daemon_fops = {
48 .owner = THIS_MODULE,
49 .open = cachefiles_daemon_open,
50 .release = cachefiles_daemon_release,
51 .read = cachefiles_daemon_read,
52 .write = cachefiles_daemon_write,
53 .poll = cachefiles_daemon_poll,
54 .llseek = noop_llseek,
55};
56
57struct cachefiles_daemon_cmd {
58 char name[8];
59 int (*handler)(struct cachefiles_cache *cache, char *args);
60};
61
62static const struct cachefiles_daemon_cmd cachefiles_daemon_cmds[] = {
63 { "bind", cachefiles_daemon_bind },
64 { "brun", cachefiles_daemon_brun },
65 { "bcull", cachefiles_daemon_bcull },
66 { "bstop", cachefiles_daemon_bstop },
67 { "cull", cachefiles_daemon_cull },
68 { "debug", cachefiles_daemon_debug },
69 { "dir", cachefiles_daemon_dir },
70 { "frun", cachefiles_daemon_frun },
71 { "fcull", cachefiles_daemon_fcull },
72 { "fstop", cachefiles_daemon_fstop },
73 { "inuse", cachefiles_daemon_inuse },
74 { "secctx", cachefiles_daemon_secctx },
75 { "tag", cachefiles_daemon_tag },
76 { "", NULL }
77};
78
79
80/*
81 * do various checks
82 */
83static int cachefiles_daemon_open(struct inode *inode, struct file *file)
84{
85 struct cachefiles_cache *cache;
86
87 _enter("");
88
89 /* only the superuser may do this */
90 if (!capable(CAP_SYS_ADMIN))
91 return -EPERM;
92
93 /* the cachefiles device may only be open once at a time */
94 if (xchg(&cachefiles_open, 1) == 1)
95 return -EBUSY;
96
97 /* allocate a cache record */
98 cache = kzalloc(sizeof(struct cachefiles_cache), GFP_KERNEL);
99 if (!cache) {
100 cachefiles_open = 0;
101 return -ENOMEM;
102 }
103
104 mutex_init(&cache->daemon_mutex);
105 cache->active_nodes = RB_ROOT;
106 rwlock_init(&cache->active_lock);
107 init_waitqueue_head(&cache->daemon_pollwq);
108
109 /* set default caching limits
110 * - limit at 1% free space and/or free files
111 * - cull below 5% free space and/or free files
112 * - cease culling above 7% free space and/or free files
113 */
114 cache->frun_percent = 7;
115 cache->fcull_percent = 5;
116 cache->fstop_percent = 1;
117 cache->brun_percent = 7;
118 cache->bcull_percent = 5;
119 cache->bstop_percent = 1;
120
121 file->private_data = cache;
122 cache->cachefilesd = file;
123 return 0;
124}
125
126/*
127 * release a cache
128 */
129static int cachefiles_daemon_release(struct inode *inode, struct file *file)
130{
131 struct cachefiles_cache *cache = file->private_data;
132
133 _enter("");
134
135 ASSERT(cache);
136
137 set_bit(CACHEFILES_DEAD, &cache->flags);
138
139 cachefiles_daemon_unbind(cache);
140
141 ASSERT(!cache->active_nodes.rb_node);
142
143 /* clean up the control file interface */
144 cache->cachefilesd = NULL;
145 file->private_data = NULL;
146 cachefiles_open = 0;
147
148 kfree(cache);
149
150 _leave("");
151 return 0;
152}
153
154/*
155 * read the cache state
156 */
157static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer,
158 size_t buflen, loff_t *pos)
159{
160 struct cachefiles_cache *cache = file->private_data;
161 unsigned long long b_released;
162 unsigned f_released;
163 char buffer[256];
164 int n;
165
166 //_enter(",,%zu,", buflen);
167
168 if (!test_bit(CACHEFILES_READY, &cache->flags))
169 return 0;
170
171 /* check how much space the cache has */
172 cachefiles_has_space(cache, 0, 0);
173
174 /* summarise */
175 f_released = atomic_xchg(&cache->f_released, 0);
176 b_released = atomic_long_xchg(&cache->b_released, 0);
177 clear_bit(CACHEFILES_STATE_CHANGED, &cache->flags);
178
179 n = snprintf(buffer, sizeof(buffer),
180 "cull=%c"
181 " frun=%llx"
182 " fcull=%llx"
183 " fstop=%llx"
184 " brun=%llx"
185 " bcull=%llx"
186 " bstop=%llx"
187 " freleased=%x"
188 " breleased=%llx",
189 test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '0',
190 (unsigned long long) cache->frun,
191 (unsigned long long) cache->fcull,
192 (unsigned long long) cache->fstop,
193 (unsigned long long) cache->brun,
194 (unsigned long long) cache->bcull,
195 (unsigned long long) cache->bstop,
196 f_released,
197 b_released);
198
199 if (n > buflen)
200 return -EMSGSIZE;
201
202 if (copy_to_user(_buffer, buffer, n) != 0)
203 return -EFAULT;
204
205 return n;
206}
207
208/*
209 * command the cache
210 */
211static ssize_t cachefiles_daemon_write(struct file *file,
212 const char __user *_data,
213 size_t datalen,
214 loff_t *pos)
215{
216 const struct cachefiles_daemon_cmd *cmd;
217 struct cachefiles_cache *cache = file->private_data;
218 ssize_t ret;
219 char *data, *args, *cp;
220
221 //_enter(",,%zu,", datalen);
222
223 ASSERT(cache);
224
225 if (test_bit(CACHEFILES_DEAD, &cache->flags))
226 return -EIO;
227
228 if (datalen < 0 || datalen > PAGE_SIZE - 1)
229 return -EOPNOTSUPP;
230
231 /* drag the command string into the kernel so we can parse it */
232 data = memdup_user_nul(_data, datalen);
233 if (IS_ERR(data))
234 return PTR_ERR(data);
235
236 ret = -EINVAL;
237 if (memchr(data, '\0', datalen))
238 goto error;
239
240 /* strip any newline */
241 cp = memchr(data, '\n', datalen);
242 if (cp) {
243 if (cp == data)
244 goto error;
245
246 *cp = '\0';
247 }
248
249 /* parse the command */
250 ret = -EOPNOTSUPP;
251
252 for (args = data; *args; args++)
253 if (isspace(*args))
254 break;
255 if (*args) {
256 if (args == data)
257 goto error;
258 *args = '\0';
259 args = skip_spaces(++args);
260 }
261
262 /* run the appropriate command handler */
263 for (cmd = cachefiles_daemon_cmds; cmd->name[0]; cmd++)
264 if (strcmp(cmd->name, data) == 0)
265 goto found_command;
266
267error:
268 kfree(data);
269 //_leave(" = %zd", ret);
270 return ret;
271
272found_command:
273 mutex_lock(&cache->daemon_mutex);
274
275 ret = -EIO;
276 if (!test_bit(CACHEFILES_DEAD, &cache->flags))
277 ret = cmd->handler(cache, args);
278
279 mutex_unlock(&cache->daemon_mutex);
280
281 if (ret == 0)
282 ret = datalen;
283 goto error;
284}
285
286/*
287 * poll for culling state
288 * - use EPOLLOUT to indicate culling state
289 */
290static __poll_t cachefiles_daemon_poll(struct file *file,
291 struct poll_table_struct *poll)
292{
293 struct cachefiles_cache *cache = file->private_data;
294 __poll_t mask;
295
296 poll_wait(file, &cache->daemon_pollwq, poll);
297 mask = 0;
298
299 if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
300 mask |= EPOLLIN;
301
302 if (test_bit(CACHEFILES_CULLING, &cache->flags))
303 mask |= EPOLLOUT;
304
305 return mask;
306}
307
308/*
309 * give a range error for cache space constraints
310 * - can be tail-called
311 */
312static int cachefiles_daemon_range_error(struct cachefiles_cache *cache,
313 char *args)
314{
315 pr_err("Free space limits must be in range 0%%<=stop<cull<run<100%%\n");
316
317 return -EINVAL;
318}
319
320/*
321 * set the percentage of files at which to stop culling
322 * - command: "frun <N>%"
323 */
324static int cachefiles_daemon_frun(struct cachefiles_cache *cache, char *args)
325{
326 unsigned long frun;
327
328 _enter(",%s", args);
329
330 if (!*args)
331 return -EINVAL;
332
333 frun = simple_strtoul(args, &args, 10);
334 if (args[0] != '%' || args[1] != '\0')
335 return -EINVAL;
336
337 if (frun <= cache->fcull_percent || frun >= 100)
338 return cachefiles_daemon_range_error(cache, args);
339
340 cache->frun_percent = frun;
341 return 0;
342}
343
344/*
345 * set the percentage of files at which to start culling
346 * - command: "fcull <N>%"
347 */
348static int cachefiles_daemon_fcull(struct cachefiles_cache *cache, char *args)
349{
350 unsigned long fcull;
351
352 _enter(",%s", args);
353
354 if (!*args)
355 return -EINVAL;
356
357 fcull = simple_strtoul(args, &args, 10);
358 if (args[0] != '%' || args[1] != '\0')
359 return -EINVAL;
360
361 if (fcull <= cache->fstop_percent || fcull >= cache->frun_percent)
362 return cachefiles_daemon_range_error(cache, args);
363
364 cache->fcull_percent = fcull;
365 return 0;
366}
367
368/*
369 * set the percentage of files at which to stop allocating
370 * - command: "fstop <N>%"
371 */
372static int cachefiles_daemon_fstop(struct cachefiles_cache *cache, char *args)
373{
374 unsigned long fstop;
375
376 _enter(",%s", args);
377
378 if (!*args)
379 return -EINVAL;
380
381 fstop = simple_strtoul(args, &args, 10);
382 if (args[0] != '%' || args[1] != '\0')
383 return -EINVAL;
384
385 if (fstop < 0 || fstop >= cache->fcull_percent)
386 return cachefiles_daemon_range_error(cache, args);
387
388 cache->fstop_percent = fstop;
389 return 0;
390}
391
392/*
393 * set the percentage of blocks at which to stop culling
394 * - command: "brun <N>%"
395 */
396static int cachefiles_daemon_brun(struct cachefiles_cache *cache, char *args)
397{
398 unsigned long brun;
399
400 _enter(",%s", args);
401
402 if (!*args)
403 return -EINVAL;
404
405 brun = simple_strtoul(args, &args, 10);
406 if (args[0] != '%' || args[1] != '\0')
407 return -EINVAL;
408
409 if (brun <= cache->bcull_percent || brun >= 100)
410 return cachefiles_daemon_range_error(cache, args);
411
412 cache->brun_percent = brun;
413 return 0;
414}
415
416/*
417 * set the percentage of blocks at which to start culling
418 * - command: "bcull <N>%"
419 */
420static int cachefiles_daemon_bcull(struct cachefiles_cache *cache, char *args)
421{
422 unsigned long bcull;
423
424 _enter(",%s", args);
425
426 if (!*args)
427 return -EINVAL;
428
429 bcull = simple_strtoul(args, &args, 10);
430 if (args[0] != '%' || args[1] != '\0')
431 return -EINVAL;
432
433 if (bcull <= cache->bstop_percent || bcull >= cache->brun_percent)
434 return cachefiles_daemon_range_error(cache, args);
435
436 cache->bcull_percent = bcull;
437 return 0;
438}
439
440/*
441 * set the percentage of blocks at which to stop allocating
442 * - command: "bstop <N>%"
443 */
444static int cachefiles_daemon_bstop(struct cachefiles_cache *cache, char *args)
445{
446 unsigned long bstop;
447
448 _enter(",%s", args);
449
450 if (!*args)
451 return -EINVAL;
452
453 bstop = simple_strtoul(args, &args, 10);
454 if (args[0] != '%' || args[1] != '\0')
455 return -EINVAL;
456
457 if (bstop < 0 || bstop >= cache->bcull_percent)
458 return cachefiles_daemon_range_error(cache, args);
459
460 cache->bstop_percent = bstop;
461 return 0;
462}
463
464/*
465 * set the cache directory
466 * - command: "dir <name>"
467 */
468static int cachefiles_daemon_dir(struct cachefiles_cache *cache, char *args)
469{
470 char *dir;
471
472 _enter(",%s", args);
473
474 if (!*args) {
475 pr_err("Empty directory specified\n");
476 return -EINVAL;
477 }
478
479 if (cache->rootdirname) {
480 pr_err("Second cache directory specified\n");
481 return -EEXIST;
482 }
483
484 dir = kstrdup(args, GFP_KERNEL);
485 if (!dir)
486 return -ENOMEM;
487
488 cache->rootdirname = dir;
489 return 0;
490}
491
492/*
493 * set the cache security context
494 * - command: "secctx <ctx>"
495 */
496static int cachefiles_daemon_secctx(struct cachefiles_cache *cache, char *args)
497{
498 char *secctx;
499
500 _enter(",%s", args);
501
502 if (!*args) {
503 pr_err("Empty security context specified\n");
504 return -EINVAL;
505 }
506
507 if (cache->secctx) {
508 pr_err("Second security context specified\n");
509 return -EINVAL;
510 }
511
512 secctx = kstrdup(args, GFP_KERNEL);
513 if (!secctx)
514 return -ENOMEM;
515
516 cache->secctx = secctx;
517 return 0;
518}
519
520/*
521 * set the cache tag
522 * - command: "tag <name>"
523 */
524static int cachefiles_daemon_tag(struct cachefiles_cache *cache, char *args)
525{
526 char *tag;
527
528 _enter(",%s", args);
529
530 if (!*args) {
531 pr_err("Empty tag specified\n");
532 return -EINVAL;
533 }
534
535 if (cache->tag)
536 return -EEXIST;
537
538 tag = kstrdup(args, GFP_KERNEL);
539 if (!tag)
540 return -ENOMEM;
541
542 cache->tag = tag;
543 return 0;
544}
545
546/*
547 * request a node in the cache be culled from the current working directory
548 * - command: "cull <name>"
549 */
550static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args)
551{
552 struct path path;
553 const struct cred *saved_cred;
554 int ret;
555
556 _enter(",%s", args);
557
558 if (strchr(args, '/'))
559 goto inval;
560
561 if (!test_bit(CACHEFILES_READY, &cache->flags)) {
562 pr_err("cull applied to unready cache\n");
563 return -EIO;
564 }
565
566 if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
567 pr_err("cull applied to dead cache\n");
568 return -EIO;
569 }
570
571 /* extract the directory dentry from the cwd */
572 get_fs_pwd(current->fs, &path);
573
574 if (!d_can_lookup(path.dentry))
575 goto notdir;
576
577 cachefiles_begin_secure(cache, &saved_cred);
578 ret = cachefiles_cull(cache, path.dentry, args);
579 cachefiles_end_secure(cache, saved_cred);
580
581 path_put(&path);
582 _leave(" = %d", ret);
583 return ret;
584
585notdir:
586 path_put(&path);
587 pr_err("cull command requires dirfd to be a directory\n");
588 return -ENOTDIR;
589
590inval:
591 pr_err("cull command requires dirfd and filename\n");
592 return -EINVAL;
593}
594
595/*
596 * set debugging mode
597 * - command: "debug <mask>"
598 */
599static int cachefiles_daemon_debug(struct cachefiles_cache *cache, char *args)
600{
601 unsigned long mask;
602
603 _enter(",%s", args);
604
605 mask = simple_strtoul(args, &args, 0);
606 if (args[0] != '\0')
607 goto inval;
608
609 cachefiles_debug = mask;
610 _leave(" = 0");
611 return 0;
612
613inval:
614 pr_err("debug command requires mask\n");
615 return -EINVAL;
616}
617
618/*
619 * find out whether an object in the current working directory is in use or not
620 * - command: "inuse <name>"
621 */
622static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args)
623{
624 struct path path;
625 const struct cred *saved_cred;
626 int ret;
627
628 //_enter(",%s", args);
629
630 if (strchr(args, '/'))
631 goto inval;
632
633 if (!test_bit(CACHEFILES_READY, &cache->flags)) {
634 pr_err("inuse applied to unready cache\n");
635 return -EIO;
636 }
637
638 if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
639 pr_err("inuse applied to dead cache\n");
640 return -EIO;
641 }
642
643 /* extract the directory dentry from the cwd */
644 get_fs_pwd(current->fs, &path);
645
646 if (!d_can_lookup(path.dentry))
647 goto notdir;
648
649 cachefiles_begin_secure(cache, &saved_cred);
650 ret = cachefiles_check_in_use(cache, path.dentry, args);
651 cachefiles_end_secure(cache, saved_cred);
652
653 path_put(&path);
654 //_leave(" = %d", ret);
655 return ret;
656
657notdir:
658 path_put(&path);
659 pr_err("inuse command requires dirfd to be a directory\n");
660 return -ENOTDIR;
661
662inval:
663 pr_err("inuse command requires dirfd and filename\n");
664 return -EINVAL;
665}
666
667/*
668 * see if we have space for a number of pages and/or a number of files in the
669 * cache
670 */
671int cachefiles_has_space(struct cachefiles_cache *cache,
672 unsigned fnr, unsigned bnr)
673{
674 struct kstatfs stats;
675 struct path path = {
676 .mnt = cache->mnt,
677 .dentry = cache->mnt->mnt_root,
678 };
679 int ret;
680
681 //_enter("{%llu,%llu,%llu,%llu,%llu,%llu},%u,%u",
682 // (unsigned long long) cache->frun,
683 // (unsigned long long) cache->fcull,
684 // (unsigned long long) cache->fstop,
685 // (unsigned long long) cache->brun,
686 // (unsigned long long) cache->bcull,
687 // (unsigned long long) cache->bstop,
688 // fnr, bnr);
689
690 /* find out how many pages of blockdev are available */
691 memset(&stats, 0, sizeof(stats));
692
693 ret = vfs_statfs(&path, &stats);
694 if (ret < 0) {
695 if (ret == -EIO)
696 cachefiles_io_error(cache, "statfs failed");
697 _leave(" = %d", ret);
698 return ret;
699 }
700
701 stats.f_bavail >>= cache->bshift;
702
703 //_debug("avail %llu,%llu",
704 // (unsigned long long) stats.f_ffree,
705 // (unsigned long long) stats.f_bavail);
706
707 /* see if there is sufficient space */
708 if (stats.f_ffree > fnr)
709 stats.f_ffree -= fnr;
710 else
711 stats.f_ffree = 0;
712
713 if (stats.f_bavail > bnr)
714 stats.f_bavail -= bnr;
715 else
716 stats.f_bavail = 0;
717
718 ret = -ENOBUFS;
719 if (stats.f_ffree < cache->fstop ||
720 stats.f_bavail < cache->bstop)
721 goto begin_cull;
722
723 ret = 0;
724 if (stats.f_ffree < cache->fcull ||
725 stats.f_bavail < cache->bcull)
726 goto begin_cull;
727
728 if (test_bit(CACHEFILES_CULLING, &cache->flags) &&
729 stats.f_ffree >= cache->frun &&
730 stats.f_bavail >= cache->brun &&
731 test_and_clear_bit(CACHEFILES_CULLING, &cache->flags)
732 ) {
733 _debug("cease culling");
734 cachefiles_state_changed(cache);
735 }
736
737 //_leave(" = 0");
738 return 0;
739
740begin_cull:
741 if (!test_and_set_bit(CACHEFILES_CULLING, &cache->flags)) {
742 _debug("### CULL CACHE ###");
743 cachefiles_state_changed(cache);
744 }
745
746 _leave(" = %d", ret);
747 return ret;
748}
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 (dhowells@redhat.com)
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/statfs.h>
19#include <linux/ctype.h>
20#include <linux/string.h>
21#include <linux/fs_struct.h>
22#include "internal.h"
23
24static int cachefiles_daemon_open(struct inode *, struct file *);
25static int cachefiles_daemon_release(struct inode *, struct file *);
26static ssize_t cachefiles_daemon_read(struct file *, char __user *, size_t,
27 loff_t *);
28static ssize_t cachefiles_daemon_write(struct file *, const char __user *,
29 size_t, loff_t *);
30static __poll_t cachefiles_daemon_poll(struct file *,
31 struct poll_table_struct *);
32static int cachefiles_daemon_frun(struct cachefiles_cache *, char *);
33static int cachefiles_daemon_fcull(struct cachefiles_cache *, char *);
34static int cachefiles_daemon_fstop(struct cachefiles_cache *, char *);
35static int cachefiles_daemon_brun(struct cachefiles_cache *, char *);
36static int cachefiles_daemon_bcull(struct cachefiles_cache *, char *);
37static int cachefiles_daemon_bstop(struct cachefiles_cache *, char *);
38static int cachefiles_daemon_cull(struct cachefiles_cache *, char *);
39static int cachefiles_daemon_debug(struct cachefiles_cache *, char *);
40static int cachefiles_daemon_dir(struct cachefiles_cache *, char *);
41static int cachefiles_daemon_inuse(struct cachefiles_cache *, char *);
42static int cachefiles_daemon_secctx(struct cachefiles_cache *, char *);
43static int cachefiles_daemon_tag(struct cachefiles_cache *, char *);
44static int cachefiles_daemon_bind(struct cachefiles_cache *, char *);
45static void cachefiles_daemon_unbind(struct cachefiles_cache *);
46
47static unsigned long cachefiles_open;
48
49const struct file_operations cachefiles_daemon_fops = {
50 .owner = THIS_MODULE,
51 .open = cachefiles_daemon_open,
52 .release = cachefiles_daemon_release,
53 .read = cachefiles_daemon_read,
54 .write = cachefiles_daemon_write,
55 .poll = cachefiles_daemon_poll,
56 .llseek = noop_llseek,
57};
58
59struct cachefiles_daemon_cmd {
60 char name[8];
61 int (*handler)(struct cachefiles_cache *cache, char *args);
62};
63
64static const struct cachefiles_daemon_cmd cachefiles_daemon_cmds[] = {
65 { "bind", cachefiles_daemon_bind },
66 { "brun", cachefiles_daemon_brun },
67 { "bcull", cachefiles_daemon_bcull },
68 { "bstop", cachefiles_daemon_bstop },
69 { "cull", cachefiles_daemon_cull },
70 { "debug", cachefiles_daemon_debug },
71 { "dir", cachefiles_daemon_dir },
72 { "frun", cachefiles_daemon_frun },
73 { "fcull", cachefiles_daemon_fcull },
74 { "fstop", cachefiles_daemon_fstop },
75 { "inuse", cachefiles_daemon_inuse },
76 { "secctx", cachefiles_daemon_secctx },
77 { "tag", cachefiles_daemon_tag },
78#ifdef CONFIG_CACHEFILES_ONDEMAND
79 { "copen", cachefiles_ondemand_copen },
80#endif
81 { "", NULL }
82};
83
84
85/*
86 * Prepare a cache for caching.
87 */
88static int cachefiles_daemon_open(struct inode *inode, struct file *file)
89{
90 struct cachefiles_cache *cache;
91
92 _enter("");
93
94 /* only the superuser may do this */
95 if (!capable(CAP_SYS_ADMIN))
96 return -EPERM;
97
98 /* the cachefiles device may only be open once at a time */
99 if (xchg(&cachefiles_open, 1) == 1)
100 return -EBUSY;
101
102 /* allocate a cache record */
103 cache = kzalloc(sizeof(struct cachefiles_cache), GFP_KERNEL);
104 if (!cache) {
105 cachefiles_open = 0;
106 return -ENOMEM;
107 }
108
109 mutex_init(&cache->daemon_mutex);
110 init_waitqueue_head(&cache->daemon_pollwq);
111 INIT_LIST_HEAD(&cache->volumes);
112 INIT_LIST_HEAD(&cache->object_list);
113 spin_lock_init(&cache->object_list_lock);
114 refcount_set(&cache->unbind_pincount, 1);
115 xa_init_flags(&cache->reqs, XA_FLAGS_ALLOC);
116 xa_init_flags(&cache->ondemand_ids, XA_FLAGS_ALLOC1);
117
118 /* set default caching limits
119 * - limit at 1% free space and/or free files
120 * - cull below 5% free space and/or free files
121 * - cease culling above 7% free space and/or free files
122 */
123 cache->frun_percent = 7;
124 cache->fcull_percent = 5;
125 cache->fstop_percent = 1;
126 cache->brun_percent = 7;
127 cache->bcull_percent = 5;
128 cache->bstop_percent = 1;
129
130 file->private_data = cache;
131 cache->cachefilesd = file;
132 return 0;
133}
134
135static void cachefiles_flush_reqs(struct cachefiles_cache *cache)
136{
137 struct xarray *xa = &cache->reqs;
138 struct cachefiles_req *req;
139 unsigned long index;
140
141 /*
142 * Make sure the following two operations won't be reordered.
143 * 1) set CACHEFILES_DEAD bit
144 * 2) flush requests in the xarray
145 * Otherwise the request may be enqueued after xarray has been
146 * flushed, leaving the orphan request never being completed.
147 *
148 * CPU 1 CPU 2
149 * ===== =====
150 * flush requests in the xarray
151 * test CACHEFILES_DEAD bit
152 * enqueue the request
153 * set CACHEFILES_DEAD bit
154 */
155 smp_mb();
156
157 xa_lock(xa);
158 xa_for_each(xa, index, req) {
159 req->error = -EIO;
160 complete(&req->done);
161 }
162 xa_unlock(xa);
163
164 xa_destroy(&cache->reqs);
165 xa_destroy(&cache->ondemand_ids);
166}
167
168void cachefiles_put_unbind_pincount(struct cachefiles_cache *cache)
169{
170 if (refcount_dec_and_test(&cache->unbind_pincount)) {
171 cachefiles_daemon_unbind(cache);
172 cachefiles_open = 0;
173 kfree(cache);
174 }
175}
176
177void cachefiles_get_unbind_pincount(struct cachefiles_cache *cache)
178{
179 refcount_inc(&cache->unbind_pincount);
180}
181
182/*
183 * Release a cache.
184 */
185static int cachefiles_daemon_release(struct inode *inode, struct file *file)
186{
187 struct cachefiles_cache *cache = file->private_data;
188
189 _enter("");
190
191 ASSERT(cache);
192
193 set_bit(CACHEFILES_DEAD, &cache->flags);
194
195 if (cachefiles_in_ondemand_mode(cache))
196 cachefiles_flush_reqs(cache);
197
198 /* clean up the control file interface */
199 cache->cachefilesd = NULL;
200 file->private_data = NULL;
201
202 cachefiles_put_unbind_pincount(cache);
203
204 _leave("");
205 return 0;
206}
207
208static ssize_t cachefiles_do_daemon_read(struct cachefiles_cache *cache,
209 char __user *_buffer, size_t buflen)
210{
211 unsigned long long b_released;
212 unsigned f_released;
213 char buffer[256];
214 int n;
215
216 /* check how much space the cache has */
217 cachefiles_has_space(cache, 0, 0, cachefiles_has_space_check);
218
219 /* summarise */
220 f_released = atomic_xchg(&cache->f_released, 0);
221 b_released = atomic_long_xchg(&cache->b_released, 0);
222 clear_bit(CACHEFILES_STATE_CHANGED, &cache->flags);
223
224 n = snprintf(buffer, sizeof(buffer),
225 "cull=%c"
226 " frun=%llx"
227 " fcull=%llx"
228 " fstop=%llx"
229 " brun=%llx"
230 " bcull=%llx"
231 " bstop=%llx"
232 " freleased=%x"
233 " breleased=%llx",
234 test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '0',
235 (unsigned long long) cache->frun,
236 (unsigned long long) cache->fcull,
237 (unsigned long long) cache->fstop,
238 (unsigned long long) cache->brun,
239 (unsigned long long) cache->bcull,
240 (unsigned long long) cache->bstop,
241 f_released,
242 b_released);
243
244 if (n > buflen)
245 return -EMSGSIZE;
246
247 if (copy_to_user(_buffer, buffer, n) != 0)
248 return -EFAULT;
249
250 return n;
251}
252
253/*
254 * Read the cache state.
255 */
256static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer,
257 size_t buflen, loff_t *pos)
258{
259 struct cachefiles_cache *cache = file->private_data;
260
261 //_enter(",,%zu,", buflen);
262
263 if (!test_bit(CACHEFILES_READY, &cache->flags))
264 return 0;
265
266 if (cachefiles_in_ondemand_mode(cache))
267 return cachefiles_ondemand_daemon_read(cache, _buffer, buflen);
268 else
269 return cachefiles_do_daemon_read(cache, _buffer, buflen);
270}
271
272/*
273 * Take a command from cachefilesd, parse it and act on it.
274 */
275static ssize_t cachefiles_daemon_write(struct file *file,
276 const char __user *_data,
277 size_t datalen,
278 loff_t *pos)
279{
280 const struct cachefiles_daemon_cmd *cmd;
281 struct cachefiles_cache *cache = file->private_data;
282 ssize_t ret;
283 char *data, *args, *cp;
284
285 //_enter(",,%zu,", datalen);
286
287 ASSERT(cache);
288
289 if (test_bit(CACHEFILES_DEAD, &cache->flags))
290 return -EIO;
291
292 if (datalen > PAGE_SIZE - 1)
293 return -EOPNOTSUPP;
294
295 /* drag the command string into the kernel so we can parse it */
296 data = memdup_user_nul(_data, datalen);
297 if (IS_ERR(data))
298 return PTR_ERR(data);
299
300 ret = -EINVAL;
301 if (memchr(data, '\0', datalen))
302 goto error;
303
304 /* strip any newline */
305 cp = memchr(data, '\n', datalen);
306 if (cp) {
307 if (cp == data)
308 goto error;
309
310 *cp = '\0';
311 }
312
313 /* parse the command */
314 ret = -EOPNOTSUPP;
315
316 for (args = data; *args; args++)
317 if (isspace(*args))
318 break;
319 if (*args) {
320 if (args == data)
321 goto error;
322 *args = '\0';
323 args = skip_spaces(++args);
324 }
325
326 /* run the appropriate command handler */
327 for (cmd = cachefiles_daemon_cmds; cmd->name[0]; cmd++)
328 if (strcmp(cmd->name, data) == 0)
329 goto found_command;
330
331error:
332 kfree(data);
333 //_leave(" = %zd", ret);
334 return ret;
335
336found_command:
337 mutex_lock(&cache->daemon_mutex);
338
339 ret = -EIO;
340 if (!test_bit(CACHEFILES_DEAD, &cache->flags))
341 ret = cmd->handler(cache, args);
342
343 mutex_unlock(&cache->daemon_mutex);
344
345 if (ret == 0)
346 ret = datalen;
347 goto error;
348}
349
350/*
351 * Poll for culling state
352 * - use EPOLLOUT to indicate culling state
353 */
354static __poll_t cachefiles_daemon_poll(struct file *file,
355 struct poll_table_struct *poll)
356{
357 struct cachefiles_cache *cache = file->private_data;
358 __poll_t mask;
359
360 poll_wait(file, &cache->daemon_pollwq, poll);
361 mask = 0;
362
363 if (cachefiles_in_ondemand_mode(cache)) {
364 if (!xa_empty(&cache->reqs))
365 mask |= EPOLLIN;
366 } else {
367 if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
368 mask |= EPOLLIN;
369 }
370
371 if (test_bit(CACHEFILES_CULLING, &cache->flags))
372 mask |= EPOLLOUT;
373
374 return mask;
375}
376
377/*
378 * Give a range error for cache space constraints
379 * - can be tail-called
380 */
381static int cachefiles_daemon_range_error(struct cachefiles_cache *cache,
382 char *args)
383{
384 pr_err("Free space limits must be in range 0%%<=stop<cull<run<100%%\n");
385
386 return -EINVAL;
387}
388
389/*
390 * Set the percentage of files at which to stop culling
391 * - command: "frun <N>%"
392 */
393static int cachefiles_daemon_frun(struct cachefiles_cache *cache, char *args)
394{
395 unsigned long frun;
396
397 _enter(",%s", args);
398
399 if (!*args)
400 return -EINVAL;
401
402 frun = simple_strtoul(args, &args, 10);
403 if (args[0] != '%' || args[1] != '\0')
404 return -EINVAL;
405
406 if (frun <= cache->fcull_percent || frun >= 100)
407 return cachefiles_daemon_range_error(cache, args);
408
409 cache->frun_percent = frun;
410 return 0;
411}
412
413/*
414 * Set the percentage of files at which to start culling
415 * - command: "fcull <N>%"
416 */
417static int cachefiles_daemon_fcull(struct cachefiles_cache *cache, char *args)
418{
419 unsigned long fcull;
420
421 _enter(",%s", args);
422
423 if (!*args)
424 return -EINVAL;
425
426 fcull = simple_strtoul(args, &args, 10);
427 if (args[0] != '%' || args[1] != '\0')
428 return -EINVAL;
429
430 if (fcull <= cache->fstop_percent || fcull >= cache->frun_percent)
431 return cachefiles_daemon_range_error(cache, args);
432
433 cache->fcull_percent = fcull;
434 return 0;
435}
436
437/*
438 * Set the percentage of files at which to stop allocating
439 * - command: "fstop <N>%"
440 */
441static int cachefiles_daemon_fstop(struct cachefiles_cache *cache, char *args)
442{
443 unsigned long fstop;
444
445 _enter(",%s", args);
446
447 if (!*args)
448 return -EINVAL;
449
450 fstop = simple_strtoul(args, &args, 10);
451 if (args[0] != '%' || args[1] != '\0')
452 return -EINVAL;
453
454 if (fstop >= cache->fcull_percent)
455 return cachefiles_daemon_range_error(cache, args);
456
457 cache->fstop_percent = fstop;
458 return 0;
459}
460
461/*
462 * Set the percentage of blocks at which to stop culling
463 * - command: "brun <N>%"
464 */
465static int cachefiles_daemon_brun(struct cachefiles_cache *cache, char *args)
466{
467 unsigned long brun;
468
469 _enter(",%s", args);
470
471 if (!*args)
472 return -EINVAL;
473
474 brun = simple_strtoul(args, &args, 10);
475 if (args[0] != '%' || args[1] != '\0')
476 return -EINVAL;
477
478 if (brun <= cache->bcull_percent || brun >= 100)
479 return cachefiles_daemon_range_error(cache, args);
480
481 cache->brun_percent = brun;
482 return 0;
483}
484
485/*
486 * Set the percentage of blocks at which to start culling
487 * - command: "bcull <N>%"
488 */
489static int cachefiles_daemon_bcull(struct cachefiles_cache *cache, char *args)
490{
491 unsigned long bcull;
492
493 _enter(",%s", args);
494
495 if (!*args)
496 return -EINVAL;
497
498 bcull = simple_strtoul(args, &args, 10);
499 if (args[0] != '%' || args[1] != '\0')
500 return -EINVAL;
501
502 if (bcull <= cache->bstop_percent || bcull >= cache->brun_percent)
503 return cachefiles_daemon_range_error(cache, args);
504
505 cache->bcull_percent = bcull;
506 return 0;
507}
508
509/*
510 * Set the percentage of blocks at which to stop allocating
511 * - command: "bstop <N>%"
512 */
513static int cachefiles_daemon_bstop(struct cachefiles_cache *cache, char *args)
514{
515 unsigned long bstop;
516
517 _enter(",%s", args);
518
519 if (!*args)
520 return -EINVAL;
521
522 bstop = simple_strtoul(args, &args, 10);
523 if (args[0] != '%' || args[1] != '\0')
524 return -EINVAL;
525
526 if (bstop >= cache->bcull_percent)
527 return cachefiles_daemon_range_error(cache, args);
528
529 cache->bstop_percent = bstop;
530 return 0;
531}
532
533/*
534 * Set the cache directory
535 * - command: "dir <name>"
536 */
537static int cachefiles_daemon_dir(struct cachefiles_cache *cache, char *args)
538{
539 char *dir;
540
541 _enter(",%s", args);
542
543 if (!*args) {
544 pr_err("Empty directory specified\n");
545 return -EINVAL;
546 }
547
548 if (cache->rootdirname) {
549 pr_err("Second cache directory specified\n");
550 return -EEXIST;
551 }
552
553 dir = kstrdup(args, GFP_KERNEL);
554 if (!dir)
555 return -ENOMEM;
556
557 cache->rootdirname = dir;
558 return 0;
559}
560
561/*
562 * Set the cache security context
563 * - command: "secctx <ctx>"
564 */
565static int cachefiles_daemon_secctx(struct cachefiles_cache *cache, char *args)
566{
567 char *secctx;
568
569 _enter(",%s", args);
570
571 if (!*args) {
572 pr_err("Empty security context specified\n");
573 return -EINVAL;
574 }
575
576 if (cache->secctx) {
577 pr_err("Second security context specified\n");
578 return -EINVAL;
579 }
580
581 secctx = kstrdup(args, GFP_KERNEL);
582 if (!secctx)
583 return -ENOMEM;
584
585 cache->secctx = secctx;
586 return 0;
587}
588
589/*
590 * Set the cache tag
591 * - command: "tag <name>"
592 */
593static int cachefiles_daemon_tag(struct cachefiles_cache *cache, char *args)
594{
595 char *tag;
596
597 _enter(",%s", args);
598
599 if (!*args) {
600 pr_err("Empty tag specified\n");
601 return -EINVAL;
602 }
603
604 if (cache->tag)
605 return -EEXIST;
606
607 tag = kstrdup(args, GFP_KERNEL);
608 if (!tag)
609 return -ENOMEM;
610
611 cache->tag = tag;
612 return 0;
613}
614
615/*
616 * Request a node in the cache be culled from the current working directory
617 * - command: "cull <name>"
618 */
619static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args)
620{
621 struct path path;
622 const struct cred *saved_cred;
623 int ret;
624
625 _enter(",%s", args);
626
627 if (strchr(args, '/'))
628 goto inval;
629
630 if (!test_bit(CACHEFILES_READY, &cache->flags)) {
631 pr_err("cull applied to unready cache\n");
632 return -EIO;
633 }
634
635 if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
636 pr_err("cull applied to dead cache\n");
637 return -EIO;
638 }
639
640 get_fs_pwd(current->fs, &path);
641
642 if (!d_can_lookup(path.dentry))
643 goto notdir;
644
645 cachefiles_begin_secure(cache, &saved_cred);
646 ret = cachefiles_cull(cache, path.dentry, args);
647 cachefiles_end_secure(cache, saved_cred);
648
649 path_put(&path);
650 _leave(" = %d", ret);
651 return ret;
652
653notdir:
654 path_put(&path);
655 pr_err("cull command requires dirfd to be a directory\n");
656 return -ENOTDIR;
657
658inval:
659 pr_err("cull command requires dirfd and filename\n");
660 return -EINVAL;
661}
662
663/*
664 * Set debugging mode
665 * - command: "debug <mask>"
666 */
667static int cachefiles_daemon_debug(struct cachefiles_cache *cache, char *args)
668{
669 unsigned long mask;
670
671 _enter(",%s", args);
672
673 mask = simple_strtoul(args, &args, 0);
674 if (args[0] != '\0')
675 goto inval;
676
677 cachefiles_debug = mask;
678 _leave(" = 0");
679 return 0;
680
681inval:
682 pr_err("debug command requires mask\n");
683 return -EINVAL;
684}
685
686/*
687 * Find out whether an object in the current working directory is in use or not
688 * - command: "inuse <name>"
689 */
690static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args)
691{
692 struct path path;
693 const struct cred *saved_cred;
694 int ret;
695
696 //_enter(",%s", args);
697
698 if (strchr(args, '/'))
699 goto inval;
700
701 if (!test_bit(CACHEFILES_READY, &cache->flags)) {
702 pr_err("inuse applied to unready cache\n");
703 return -EIO;
704 }
705
706 if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
707 pr_err("inuse applied to dead cache\n");
708 return -EIO;
709 }
710
711 get_fs_pwd(current->fs, &path);
712
713 if (!d_can_lookup(path.dentry))
714 goto notdir;
715
716 cachefiles_begin_secure(cache, &saved_cred);
717 ret = cachefiles_check_in_use(cache, path.dentry, args);
718 cachefiles_end_secure(cache, saved_cred);
719
720 path_put(&path);
721 //_leave(" = %d", ret);
722 return ret;
723
724notdir:
725 path_put(&path);
726 pr_err("inuse command requires dirfd to be a directory\n");
727 return -ENOTDIR;
728
729inval:
730 pr_err("inuse command requires dirfd and filename\n");
731 return -EINVAL;
732}
733
734/*
735 * Bind a directory as a cache
736 */
737static int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args)
738{
739 _enter("{%u,%u,%u,%u,%u,%u},%s",
740 cache->frun_percent,
741 cache->fcull_percent,
742 cache->fstop_percent,
743 cache->brun_percent,
744 cache->bcull_percent,
745 cache->bstop_percent,
746 args);
747
748 if (cache->fstop_percent >= cache->fcull_percent ||
749 cache->fcull_percent >= cache->frun_percent ||
750 cache->frun_percent >= 100)
751 return -ERANGE;
752
753 if (cache->bstop_percent >= cache->bcull_percent ||
754 cache->bcull_percent >= cache->brun_percent ||
755 cache->brun_percent >= 100)
756 return -ERANGE;
757
758 if (!cache->rootdirname) {
759 pr_err("No cache directory specified\n");
760 return -EINVAL;
761 }
762
763 /* Don't permit already bound caches to be re-bound */
764 if (test_bit(CACHEFILES_READY, &cache->flags)) {
765 pr_err("Cache already bound\n");
766 return -EBUSY;
767 }
768
769 if (IS_ENABLED(CONFIG_CACHEFILES_ONDEMAND)) {
770 if (!strcmp(args, "ondemand")) {
771 set_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags);
772 } else if (*args) {
773 pr_err("Invalid argument to the 'bind' command\n");
774 return -EINVAL;
775 }
776 } else if (*args) {
777 pr_err("'bind' command doesn't take an argument\n");
778 return -EINVAL;
779 }
780
781 /* Make sure we have copies of the tag string */
782 if (!cache->tag) {
783 /*
784 * The tag string is released by the fops->release()
785 * function, so we don't release it on error here
786 */
787 cache->tag = kstrdup("CacheFiles", GFP_KERNEL);
788 if (!cache->tag)
789 return -ENOMEM;
790 }
791
792 return cachefiles_add_cache(cache);
793}
794
795/*
796 * Unbind a cache.
797 */
798static void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
799{
800 _enter("");
801
802 if (test_bit(CACHEFILES_READY, &cache->flags))
803 cachefiles_withdraw_cache(cache);
804
805 cachefiles_put_directory(cache->graveyard);
806 cachefiles_put_directory(cache->store);
807 mntput(cache->mnt);
808
809 kfree(cache->rootdirname);
810 kfree(cache->secctx);
811 kfree(cache->tag);
812
813 _leave("");
814}