1 /* Daemon interface
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/sched.h>
15 #include <linux/completion.h>
16 #include <linux/slab.h>
17 #include <linux/fs.h>
18 #include <linux/file.h>
19 #include <linux/namei.h>
20 #include <linux/poll.h>
21 #include <linux/mount.h>
22 #include <linux/statfs.h>
23 #include <linux/ctype.h>
24 #include <linux/string.h>
25 #include <linux/fs_struct.h>
26 #include "internal.h"
27
28 static int cachefiles_daemon_open(struct inode *, struct file *);
29 static int cachefiles_daemon_release(struct inode *, struct file *);
30 static ssize_t cachefiles_daemon_read(struct file *, char __user *, size_t,
31 loff_t *);
32 static ssize_t cachefiles_daemon_write(struct file *, const char __user *,
33 size_t, loff_t *);
34 static __poll_t cachefiles_daemon_poll(struct file *,
35 struct poll_table_struct *);
36 static int cachefiles_daemon_frun(struct cachefiles_cache *, char *);
37 static int cachefiles_daemon_fcull(struct cachefiles_cache *, char *);
38 static int cachefiles_daemon_fstop(struct cachefiles_cache *, char *);
39 static int cachefiles_daemon_brun(struct cachefiles_cache *, char *);
40 static int cachefiles_daemon_bcull(struct cachefiles_cache *, char *);
41 static int cachefiles_daemon_bstop(struct cachefiles_cache *, char *);
42 static int cachefiles_daemon_cull(struct cachefiles_cache *, char *);
43 static int cachefiles_daemon_debug(struct cachefiles_cache *, char *);
44 static int cachefiles_daemon_dir(struct cachefiles_cache *, char *);
45 static int cachefiles_daemon_inuse(struct cachefiles_cache *, char *);
46 static int cachefiles_daemon_secctx(struct cachefiles_cache *, char *);
47 static int cachefiles_daemon_tag(struct cachefiles_cache *, char *);
48
49 static unsigned long cachefiles_open;
50
51 const struct file_operations cachefiles_daemon_fops = {
52 .owner = THIS_MODULE,
53 .open = cachefiles_daemon_open,
54 .release = cachefiles_daemon_release,
55 .read = cachefiles_daemon_read,
56 .write = cachefiles_daemon_write,
57 .poll = cachefiles_daemon_poll,
58 .llseek = noop_llseek,
59 };
60
61 struct cachefiles_daemon_cmd {
62 char name[8];
63 int (*handler)(struct cachefiles_cache *cache, char *args);
64 };
65
66 static const struct cachefiles_daemon_cmd cachefiles_daemon_cmds[] = {
67 { "bind", cachefiles_daemon_bind },
68 { "brun", cachefiles_daemon_brun },
69 { "bcull", cachefiles_daemon_bcull },
70 { "bstop", cachefiles_daemon_bstop },
71 { "cull", cachefiles_daemon_cull },
72 { "debug", cachefiles_daemon_debug },
73 { "dir", cachefiles_daemon_dir },
74 { "frun", cachefiles_daemon_frun },
75 { "fcull", cachefiles_daemon_fcull },
76 { "fstop", cachefiles_daemon_fstop },
77 { "inuse", cachefiles_daemon_inuse },
78 { "secctx", cachefiles_daemon_secctx },
79 { "tag", cachefiles_daemon_tag },
80 { "", NULL }
81 };
82
83
84 /*
85 * do various checks
86 */
cachefiles_daemon_open(struct inode * inode,struct file * file)87 static int cachefiles_daemon_open(struct inode *inode, struct file *file)
88 {
89 struct cachefiles_cache *cache;
90
91 _enter("");
92
93 /* only the superuser may do this */
94 if (!capable(CAP_SYS_ADMIN))
95 return -EPERM;
96
97 /* the cachefiles device may only be open once at a time */
98 if (xchg(&cachefiles_open, 1) == 1)
99 return -EBUSY;
100
101 /* allocate a cache record */
102 cache = kzalloc(sizeof(struct cachefiles_cache), GFP_KERNEL);
103 if (!cache) {
104 cachefiles_open = 0;
105 return -ENOMEM;
106 }
107
108 mutex_init(&cache->daemon_mutex);
109 cache->active_nodes = RB_ROOT;
110 rwlock_init(&cache->active_lock);
111 init_waitqueue_head(&cache->daemon_pollwq);
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 */
cachefiles_daemon_release(struct inode * inode,struct file * file)133 static 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
143 cachefiles_daemon_unbind(cache);
144
145 ASSERT(!cache->active_nodes.rb_node);
146
147 /* clean up the control file interface */
148 cache->cachefilesd = NULL;
149 file->private_data = NULL;
150 cachefiles_open = 0;
151
152 kfree(cache);
153
154 _leave("");
155 return 0;
156 }
157
158 /*
159 * read the cache state
160 */
cachefiles_daemon_read(struct file * file,char __user * _buffer,size_t buflen,loff_t * pos)161 static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer,
162 size_t buflen, loff_t *pos)
163 {
164 struct cachefiles_cache *cache = file->private_data;
165 unsigned long long b_released;
166 unsigned f_released;
167 char buffer[256];
168 int n;
169
170 //_enter(",,%zu,", buflen);
171
172 if (!test_bit(CACHEFILES_READY, &cache->flags))
173 return 0;
174
175 /* check how much space the cache has */
176 cachefiles_has_space(cache, 0, 0);
177
178 /* summarise */
179 f_released = atomic_xchg(&cache->f_released, 0);
180 b_released = atomic_long_xchg(&cache->b_released, 0);
181 clear_bit(CACHEFILES_STATE_CHANGED, &cache->flags);
182
183 n = snprintf(buffer, sizeof(buffer),
184 "cull=%c"
185 " frun=%llx"
186 " fcull=%llx"
187 " fstop=%llx"
188 " brun=%llx"
189 " bcull=%llx"
190 " bstop=%llx"
191 " freleased=%x"
192 " breleased=%llx",
193 test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '0',
194 (unsigned long long) cache->frun,
195 (unsigned long long) cache->fcull,
196 (unsigned long long) cache->fstop,
197 (unsigned long long) cache->brun,
198 (unsigned long long) cache->bcull,
199 (unsigned long long) cache->bstop,
200 f_released,
201 b_released);
202
203 if (n > buflen)
204 return -EMSGSIZE;
205
206 if (copy_to_user(_buffer, buffer, n) != 0)
207 return -EFAULT;
208
209 return n;
210 }
211
212 /*
213 * command the cache
214 */
cachefiles_daemon_write(struct file * file,const char __user * _data,size_t datalen,loff_t * pos)215 static ssize_t cachefiles_daemon_write(struct file *file,
216 const char __user *_data,
217 size_t datalen,
218 loff_t *pos)
219 {
220 const struct cachefiles_daemon_cmd *cmd;
221 struct cachefiles_cache *cache = file->private_data;
222 ssize_t ret;
223 char *data, *args, *cp;
224
225 //_enter(",,%zu,", datalen);
226
227 ASSERT(cache);
228
229 if (test_bit(CACHEFILES_DEAD, &cache->flags))
230 return -EIO;
231
232 if (datalen < 0 || datalen > PAGE_SIZE - 1)
233 return -EOPNOTSUPP;
234
235 /* drag the command string into the kernel so we can parse it */
236 data = memdup_user_nul(_data, datalen);
237 if (IS_ERR(data))
238 return PTR_ERR(data);
239
240 ret = -EINVAL;
241 if (memchr(data, '\0', datalen))
242 goto error;
243
244 /* strip any newline */
245 cp = memchr(data, '\n', datalen);
246 if (cp) {
247 if (cp == data)
248 goto error;
249
250 *cp = '\0';
251 }
252
253 /* parse the command */
254 ret = -EOPNOTSUPP;
255
256 for (args = data; *args; args++)
257 if (isspace(*args))
258 break;
259 if (*args) {
260 if (args == data)
261 goto error;
262 *args = '\0';
263 args = skip_spaces(++args);
264 }
265
266 /* run the appropriate command handler */
267 for (cmd = cachefiles_daemon_cmds; cmd->name[0]; cmd++)
268 if (strcmp(cmd->name, data) == 0)
269 goto found_command;
270
271 error:
272 kfree(data);
273 //_leave(" = %zd", ret);
274 return ret;
275
276 found_command:
277 mutex_lock(&cache->daemon_mutex);
278
279 ret = -EIO;
280 if (!test_bit(CACHEFILES_DEAD, &cache->flags))
281 ret = cmd->handler(cache, args);
282
283 mutex_unlock(&cache->daemon_mutex);
284
285 if (ret == 0)
286 ret = datalen;
287 goto error;
288 }
289
290 /*
291 * poll for culling state
292 * - use EPOLLOUT to indicate culling state
293 */
cachefiles_daemon_poll(struct file * file,struct poll_table_struct * poll)294 static __poll_t cachefiles_daemon_poll(struct file *file,
295 struct poll_table_struct *poll)
296 {
297 struct cachefiles_cache *cache = file->private_data;
298 __poll_t mask;
299
300 poll_wait(file, &cache->daemon_pollwq, poll);
301 mask = 0;
302
303 if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
304 mask |= EPOLLIN;
305
306 if (test_bit(CACHEFILES_CULLING, &cache->flags))
307 mask |= EPOLLOUT;
308
309 return mask;
310 }
311
312 /*
313 * give a range error for cache space constraints
314 * - can be tail-called
315 */
cachefiles_daemon_range_error(struct cachefiles_cache * cache,char * args)316 static int cachefiles_daemon_range_error(struct cachefiles_cache *cache,
317 char *args)
318 {
319 pr_err("Free space limits must be in range 0%%<=stop<cull<run<100%%\n");
320
321 return -EINVAL;
322 }
323
324 /*
325 * set the percentage of files at which to stop culling
326 * - command: "frun <N>%"
327 */
cachefiles_daemon_frun(struct cachefiles_cache * cache,char * args)328 static int cachefiles_daemon_frun(struct cachefiles_cache *cache, char *args)
329 {
330 unsigned long frun;
331
332 _enter(",%s", args);
333
334 if (!*args)
335 return -EINVAL;
336
337 frun = simple_strtoul(args, &args, 10);
338 if (args[0] != '%' || args[1] != '\0')
339 return -EINVAL;
340
341 if (frun <= cache->fcull_percent || frun >= 100)
342 return cachefiles_daemon_range_error(cache, args);
343
344 cache->frun_percent = frun;
345 return 0;
346 }
347
348 /*
349 * set the percentage of files at which to start culling
350 * - command: "fcull <N>%"
351 */
cachefiles_daemon_fcull(struct cachefiles_cache * cache,char * args)352 static int cachefiles_daemon_fcull(struct cachefiles_cache *cache, char *args)
353 {
354 unsigned long fcull;
355
356 _enter(",%s", args);
357
358 if (!*args)
359 return -EINVAL;
360
361 fcull = simple_strtoul(args, &args, 10);
362 if (args[0] != '%' || args[1] != '\0')
363 return -EINVAL;
364
365 if (fcull <= cache->fstop_percent || fcull >= cache->frun_percent)
366 return cachefiles_daemon_range_error(cache, args);
367
368 cache->fcull_percent = fcull;
369 return 0;
370 }
371
372 /*
373 * set the percentage of files at which to stop allocating
374 * - command: "fstop <N>%"
375 */
cachefiles_daemon_fstop(struct cachefiles_cache * cache,char * args)376 static int cachefiles_daemon_fstop(struct cachefiles_cache *cache, char *args)
377 {
378 unsigned long fstop;
379
380 _enter(",%s", args);
381
382 if (!*args)
383 return -EINVAL;
384
385 fstop = simple_strtoul(args, &args, 10);
386 if (args[0] != '%' || args[1] != '\0')
387 return -EINVAL;
388
389 if (fstop < 0 || fstop >= cache->fcull_percent)
390 return cachefiles_daemon_range_error(cache, args);
391
392 cache->fstop_percent = fstop;
393 return 0;
394 }
395
396 /*
397 * set the percentage of blocks at which to stop culling
398 * - command: "brun <N>%"
399 */
cachefiles_daemon_brun(struct cachefiles_cache * cache,char * args)400 static int cachefiles_daemon_brun(struct cachefiles_cache *cache, char *args)
401 {
402 unsigned long brun;
403
404 _enter(",%s", args);
405
406 if (!*args)
407 return -EINVAL;
408
409 brun = simple_strtoul(args, &args, 10);
410 if (args[0] != '%' || args[1] != '\0')
411 return -EINVAL;
412
413 if (brun <= cache->bcull_percent || brun >= 100)
414 return cachefiles_daemon_range_error(cache, args);
415
416 cache->brun_percent = brun;
417 return 0;
418 }
419
420 /*
421 * set the percentage of blocks at which to start culling
422 * - command: "bcull <N>%"
423 */
cachefiles_daemon_bcull(struct cachefiles_cache * cache,char * args)424 static int cachefiles_daemon_bcull(struct cachefiles_cache *cache, char *args)
425 {
426 unsigned long bcull;
427
428 _enter(",%s", args);
429
430 if (!*args)
431 return -EINVAL;
432
433 bcull = simple_strtoul(args, &args, 10);
434 if (args[0] != '%' || args[1] != '\0')
435 return -EINVAL;
436
437 if (bcull <= cache->bstop_percent || bcull >= cache->brun_percent)
438 return cachefiles_daemon_range_error(cache, args);
439
440 cache->bcull_percent = bcull;
441 return 0;
442 }
443
444 /*
445 * set the percentage of blocks at which to stop allocating
446 * - command: "bstop <N>%"
447 */
cachefiles_daemon_bstop(struct cachefiles_cache * cache,char * args)448 static int cachefiles_daemon_bstop(struct cachefiles_cache *cache, char *args)
449 {
450 unsigned long bstop;
451
452 _enter(",%s", args);
453
454 if (!*args)
455 return -EINVAL;
456
457 bstop = simple_strtoul(args, &args, 10);
458 if (args[0] != '%' || args[1] != '\0')
459 return -EINVAL;
460
461 if (bstop < 0 || bstop >= cache->bcull_percent)
462 return cachefiles_daemon_range_error(cache, args);
463
464 cache->bstop_percent = bstop;
465 return 0;
466 }
467
468 /*
469 * set the cache directory
470 * - command: "dir <name>"
471 */
cachefiles_daemon_dir(struct cachefiles_cache * cache,char * args)472 static int cachefiles_daemon_dir(struct cachefiles_cache *cache, char *args)
473 {
474 char *dir;
475
476 _enter(",%s", args);
477
478 if (!*args) {
479 pr_err("Empty directory specified\n");
480 return -EINVAL;
481 }
482
483 if (cache->rootdirname) {
484 pr_err("Second cache directory specified\n");
485 return -EEXIST;
486 }
487
488 dir = kstrdup(args, GFP_KERNEL);
489 if (!dir)
490 return -ENOMEM;
491
492 cache->rootdirname = dir;
493 return 0;
494 }
495
496 /*
497 * set the cache security context
498 * - command: "secctx <ctx>"
499 */
cachefiles_daemon_secctx(struct cachefiles_cache * cache,char * args)500 static int cachefiles_daemon_secctx(struct cachefiles_cache *cache, char *args)
501 {
502 char *secctx;
503
504 _enter(",%s", args);
505
506 if (!*args) {
507 pr_err("Empty security context specified\n");
508 return -EINVAL;
509 }
510
511 if (cache->secctx) {
512 pr_err("Second security context specified\n");
513 return -EINVAL;
514 }
515
516 secctx = kstrdup(args, GFP_KERNEL);
517 if (!secctx)
518 return -ENOMEM;
519
520 cache->secctx = secctx;
521 return 0;
522 }
523
524 /*
525 * set the cache tag
526 * - command: "tag <name>"
527 */
cachefiles_daemon_tag(struct cachefiles_cache * cache,char * args)528 static int cachefiles_daemon_tag(struct cachefiles_cache *cache, char *args)
529 {
530 char *tag;
531
532 _enter(",%s", args);
533
534 if (!*args) {
535 pr_err("Empty tag specified\n");
536 return -EINVAL;
537 }
538
539 if (cache->tag)
540 return -EEXIST;
541
542 tag = kstrdup(args, GFP_KERNEL);
543 if (!tag)
544 return -ENOMEM;
545
546 cache->tag = tag;
547 return 0;
548 }
549
550 /*
551 * request a node in the cache be culled from the current working directory
552 * - command: "cull <name>"
553 */
cachefiles_daemon_cull(struct cachefiles_cache * cache,char * args)554 static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args)
555 {
556 struct path path;
557 const struct cred *saved_cred;
558 int ret;
559
560 _enter(",%s", args);
561
562 if (strchr(args, '/'))
563 goto inval;
564
565 if (!test_bit(CACHEFILES_READY, &cache->flags)) {
566 pr_err("cull applied to unready cache\n");
567 return -EIO;
568 }
569
570 if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
571 pr_err("cull applied to dead cache\n");
572 return -EIO;
573 }
574
575 /* extract the directory dentry from the cwd */
576 get_fs_pwd(current->fs, &path);
577
578 if (!d_can_lookup(path.dentry))
579 goto notdir;
580
581 cachefiles_begin_secure(cache, &saved_cred);
582 ret = cachefiles_cull(cache, path.dentry, args);
583 cachefiles_end_secure(cache, saved_cred);
584
585 path_put(&path);
586 _leave(" = %d", ret);
587 return ret;
588
589 notdir:
590 path_put(&path);
591 pr_err("cull command requires dirfd to be a directory\n");
592 return -ENOTDIR;
593
594 inval:
595 pr_err("cull command requires dirfd and filename\n");
596 return -EINVAL;
597 }
598
599 /*
600 * set debugging mode
601 * - command: "debug <mask>"
602 */
cachefiles_daemon_debug(struct cachefiles_cache * cache,char * args)603 static int cachefiles_daemon_debug(struct cachefiles_cache *cache, char *args)
604 {
605 unsigned long mask;
606
607 _enter(",%s", args);
608
609 mask = simple_strtoul(args, &args, 0);
610 if (args[0] != '\0')
611 goto inval;
612
613 cachefiles_debug = mask;
614 _leave(" = 0");
615 return 0;
616
617 inval:
618 pr_err("debug command requires mask\n");
619 return -EINVAL;
620 }
621
622 /*
623 * find out whether an object in the current working directory is in use or not
624 * - command: "inuse <name>"
625 */
cachefiles_daemon_inuse(struct cachefiles_cache * cache,char * args)626 static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args)
627 {
628 struct path path;
629 const struct cred *saved_cred;
630 int ret;
631
632 //_enter(",%s", args);
633
634 if (strchr(args, '/'))
635 goto inval;
636
637 if (!test_bit(CACHEFILES_READY, &cache->flags)) {
638 pr_err("inuse applied to unready cache\n");
639 return -EIO;
640 }
641
642 if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
643 pr_err("inuse applied to dead cache\n");
644 return -EIO;
645 }
646
647 /* extract the directory dentry from the cwd */
648 get_fs_pwd(current->fs, &path);
649
650 if (!d_can_lookup(path.dentry))
651 goto notdir;
652
653 cachefiles_begin_secure(cache, &saved_cred);
654 ret = cachefiles_check_in_use(cache, path.dentry, args);
655 cachefiles_end_secure(cache, saved_cred);
656
657 path_put(&path);
658 //_leave(" = %d", ret);
659 return ret;
660
661 notdir:
662 path_put(&path);
663 pr_err("inuse command requires dirfd to be a directory\n");
664 return -ENOTDIR;
665
666 inval:
667 pr_err("inuse command requires dirfd and filename\n");
668 return -EINVAL;
669 }
670
671 /*
672 * see if we have space for a number of pages and/or a number of files in the
673 * cache
674 */
cachefiles_has_space(struct cachefiles_cache * cache,unsigned fnr,unsigned bnr)675 int cachefiles_has_space(struct cachefiles_cache *cache,
676 unsigned fnr, unsigned bnr)
677 {
678 struct kstatfs stats;
679 struct path path = {
680 .mnt = cache->mnt,
681 .dentry = cache->mnt->mnt_root,
682 };
683 int ret;
684
685 //_enter("{%llu,%llu,%llu,%llu,%llu,%llu},%u,%u",
686 // (unsigned long long) cache->frun,
687 // (unsigned long long) cache->fcull,
688 // (unsigned long long) cache->fstop,
689 // (unsigned long long) cache->brun,
690 // (unsigned long long) cache->bcull,
691 // (unsigned long long) cache->bstop,
692 // fnr, bnr);
693
694 /* find out how many pages of blockdev are available */
695 memset(&stats, 0, sizeof(stats));
696
697 ret = vfs_statfs(&path, &stats);
698 if (ret < 0) {
699 if (ret == -EIO)
700 cachefiles_io_error(cache, "statfs failed");
701 _leave(" = %d", ret);
702 return ret;
703 }
704
705 stats.f_bavail >>= cache->bshift;
706
707 //_debug("avail %llu,%llu",
708 // (unsigned long long) stats.f_ffree,
709 // (unsigned long long) stats.f_bavail);
710
711 /* see if there is sufficient space */
712 if (stats.f_ffree > fnr)
713 stats.f_ffree -= fnr;
714 else
715 stats.f_ffree = 0;
716
717 if (stats.f_bavail > bnr)
718 stats.f_bavail -= bnr;
719 else
720 stats.f_bavail = 0;
721
722 ret = -ENOBUFS;
723 if (stats.f_ffree < cache->fstop ||
724 stats.f_bavail < cache->bstop)
725 goto begin_cull;
726
727 ret = 0;
728 if (stats.f_ffree < cache->fcull ||
729 stats.f_bavail < cache->bcull)
730 goto begin_cull;
731
732 if (test_bit(CACHEFILES_CULLING, &cache->flags) &&
733 stats.f_ffree >= cache->frun &&
734 stats.f_bavail >= cache->brun &&
735 test_and_clear_bit(CACHEFILES_CULLING, &cache->flags)
736 ) {
737 _debug("cease culling");
738 cachefiles_state_changed(cache);
739 }
740
741 //_leave(" = 0");
742 return 0;
743
744 begin_cull:
745 if (!test_and_set_bit(CACHEFILES_CULLING, &cache->flags)) {
746 _debug("### CULL CACHE ###");
747 cachefiles_state_changed(cache);
748 }
749
750 _leave(" = %d", ret);
751 return ret;
752 }
753