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TOMOYO Linux Cross Reference
Linux/fs/cachefiles/daemon.c

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  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 unsigned int 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  */
 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  */
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  */
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         char buffer[256];
166         int n;
167 
168         //_enter(",,%zu,", buflen);
169 
170         if (!test_bit(CACHEFILES_READY, &cache->flags))
171                 return 0;
172 
173         /* check how much space the cache has */
174         cachefiles_has_space(cache, 0, 0);
175 
176         /* summarise */
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                      test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '',
188                      (unsigned long long) cache->frun,
189                      (unsigned long long) cache->fcull,
190                      (unsigned long long) cache->fstop,
191                      (unsigned long long) cache->brun,
192                      (unsigned long long) cache->bcull,
193                      (unsigned long long) cache->bstop
194                      );
195 
196         if (n > buflen)
197                 return -EMSGSIZE;
198 
199         if (copy_to_user(_buffer, buffer, n) != 0)
200                 return -EFAULT;
201 
202         return n;
203 }
204 
205 /*
206  * command the cache
207  */
208 static ssize_t cachefiles_daemon_write(struct file *file,
209                                        const char __user *_data,
210                                        size_t datalen,
211                                        loff_t *pos)
212 {
213         const struct cachefiles_daemon_cmd *cmd;
214         struct cachefiles_cache *cache = file->private_data;
215         ssize_t ret;
216         char *data, *args, *cp;
217 
218         //_enter(",,%zu,", datalen);
219 
220         ASSERT(cache);
221 
222         if (test_bit(CACHEFILES_DEAD, &cache->flags))
223                 return -EIO;
224 
225         if (datalen < 0 || datalen > PAGE_SIZE - 1)
226                 return -EOPNOTSUPP;
227 
228         /* drag the command string into the kernel so we can parse it */
229         data = kmalloc(datalen + 1, GFP_KERNEL);
230         if (!data)
231                 return -ENOMEM;
232 
233         ret = -EFAULT;
234         if (copy_from_user(data, _data, datalen) != 0)
235                 goto error;
236 
237         data[datalen] = '\0';
238 
239         ret = -EINVAL;
240         if (memchr(data, '\0', datalen))
241                 goto error;
242 
243         /* strip any newline */
244         cp = memchr(data, '\n', datalen);
245         if (cp) {
246                 if (cp == data)
247                         goto error;
248 
249                 *cp = '\0';
250         }
251 
252         /* parse the command */
253         ret = -EOPNOTSUPP;
254 
255         for (args = data; *args; args++)
256                 if (isspace(*args))
257                         break;
258         if (*args) {
259                 if (args == data)
260                         goto error;
261                 *args = '\0';
262                 args = skip_spaces(++args);
263         }
264 
265         /* run the appropriate command handler */
266         for (cmd = cachefiles_daemon_cmds; cmd->name[0]; cmd++)
267                 if (strcmp(cmd->name, data) == 0)
268                         goto found_command;
269 
270 error:
271         kfree(data);
272         //_leave(" = %zd", ret);
273         return ret;
274 
275 found_command:
276         mutex_lock(&cache->daemon_mutex);
277 
278         ret = -EIO;
279         if (!test_bit(CACHEFILES_DEAD, &cache->flags))
280                 ret = cmd->handler(cache, args);
281 
282         mutex_unlock(&cache->daemon_mutex);
283 
284         if (ret == 0)
285                 ret = datalen;
286         goto error;
287 }
288 
289 /*
290  * poll for culling state
291  * - use POLLOUT to indicate culling state
292  */
293 static unsigned int cachefiles_daemon_poll(struct file *file,
294                                            struct poll_table_struct *poll)
295 {
296         struct cachefiles_cache *cache = file->private_data;
297         unsigned int mask;
298 
299         poll_wait(file, &cache->daemon_pollwq, poll);
300         mask = 0;
301 
302         if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
303                 mask |= POLLIN;
304 
305         if (test_bit(CACHEFILES_CULLING, &cache->flags))
306                 mask |= POLLOUT;
307 
308         return mask;
309 }
310 
311 /*
312  * give a range error for cache space constraints
313  * - can be tail-called
314  */
315 static int cachefiles_daemon_range_error(struct cachefiles_cache *cache,
316                                          char *args)
317 {
318         kerror("Free space limits must be in range"
319                " 0%%<=stop<cull<run<100%%");
320 
321         return -EINVAL;
322 }
323 
324 /*
325  * set the percentage of files at which to stop culling
326  * - command: "frun <N>%"
327  */
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  */
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  */
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  */
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  */
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  */
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  */
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                 kerror("Empty directory specified");
480                 return -EINVAL;
481         }
482 
483         if (cache->rootdirname) {
484                 kerror("Second cache directory specified");
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  */
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                 kerror("Empty security context specified");
508                 return -EINVAL;
509         }
510 
511         if (cache->secctx) {
512                 kerror("Second security context specified");
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  */
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                 kerror("Empty tag specified");
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  */
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                 kerror("cull applied to unready cache");
567                 return -EIO;
568         }
569 
570         if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
571                 kerror("cull applied to dead cache");
572                 return -EIO;
573         }
574 
575         /* extract the directory dentry from the cwd */
576         get_fs_pwd(current->fs, &path);
577 
578         if (!S_ISDIR(path.dentry->d_inode->i_mode))
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         kerror("cull command requires dirfd to be a directory");
592         return -ENOTDIR;
593 
594 inval:
595         kerror("cull command requires dirfd and filename");
596         return -EINVAL;
597 }
598 
599 /*
600  * set debugging mode
601  * - command: "debug <mask>"
602  */
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         kerror("debug command requires mask");
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  */
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                 kerror("inuse applied to unready cache");
639                 return -EIO;
640         }
641 
642         if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
643                 kerror("inuse applied to dead cache");
644                 return -EIO;
645         }
646 
647         /* extract the directory dentry from the cwd */
648         get_fs_pwd(current->fs, &path);
649 
650         if (!S_ISDIR(path.dentry->d_inode->i_mode))
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         kerror("inuse command requires dirfd to be a directory");
664         return -ENOTDIR;
665 
666 inval:
667         kerror("inuse command requires dirfd and filename");
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  */
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 

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