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fuse: Trust kernel i_mtime only
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1 /*
2   FUSE: Filesystem in Userspace
3   Copyright (C) 2001-2008  Miklos Szeredi <miklos@szeredi.hu>
4
5   This program can be distributed under the terms of the GNU GPL.
6   See the file COPYING.
7 */
8
9 #include "fuse_i.h"
10
11 #include <linux/pagemap.h>
12 #include <linux/slab.h>
13 #include <linux/file.h>
14 #include <linux/seq_file.h>
15 #include <linux/init.h>
16 #include <linux/module.h>
17 #include <linux/moduleparam.h>
18 #include <linux/parser.h>
19 #include <linux/statfs.h>
20 #include <linux/random.h>
21 #include <linux/sched.h>
22 #include <linux/exportfs.h>
23
24 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
25 MODULE_DESCRIPTION("Filesystem in Userspace");
26 MODULE_LICENSE("GPL");
27
28 static struct kmem_cache *fuse_inode_cachep;
29 struct list_head fuse_conn_list;
30 DEFINE_MUTEX(fuse_mutex);
31
32 static int set_global_limit(const char *val, struct kernel_param *kp);
33
34 unsigned max_user_bgreq;
35 module_param_call(max_user_bgreq, set_global_limit, param_get_uint,
36                   &max_user_bgreq, 0644);
37 __MODULE_PARM_TYPE(max_user_bgreq, "uint");
38 MODULE_PARM_DESC(max_user_bgreq,
39  "Global limit for the maximum number of backgrounded requests an "
40  "unprivileged user can set");
41
42 unsigned max_user_congthresh;
43 module_param_call(max_user_congthresh, set_global_limit, param_get_uint,
44                   &max_user_congthresh, 0644);
45 __MODULE_PARM_TYPE(max_user_congthresh, "uint");
46 MODULE_PARM_DESC(max_user_congthresh,
47  "Global limit for the maximum congestion threshold an "
48  "unprivileged user can set");
49
50 #define FUSE_SUPER_MAGIC 0x65735546
51
52 #define FUSE_DEFAULT_BLKSIZE 512
53
54 /** Maximum number of outstanding background requests */
55 #define FUSE_DEFAULT_MAX_BACKGROUND 12
56
57 /** Congestion starts at 75% of maximum */
58 #define FUSE_DEFAULT_CONGESTION_THRESHOLD (FUSE_DEFAULT_MAX_BACKGROUND * 3 / 4)
59
60 struct fuse_mount_data {
61         int fd;
62         unsigned rootmode;
63         kuid_t user_id;
64         kgid_t group_id;
65         unsigned fd_present:1;
66         unsigned rootmode_present:1;
67         unsigned user_id_present:1;
68         unsigned group_id_present:1;
69         unsigned flags;
70         unsigned max_read;
71         unsigned blksize;
72 };
73
74 struct fuse_forget_link *fuse_alloc_forget(void)
75 {
76         return kzalloc(sizeof(struct fuse_forget_link), GFP_KERNEL);
77 }
78
79 static struct inode *fuse_alloc_inode(struct super_block *sb)
80 {
81         struct inode *inode;
82         struct fuse_inode *fi;
83
84         inode = kmem_cache_alloc(fuse_inode_cachep, GFP_KERNEL);
85         if (!inode)
86                 return NULL;
87
88         fi = get_fuse_inode(inode);
89         fi->i_time = 0;
90         fi->nodeid = 0;
91         fi->nlookup = 0;
92         fi->attr_version = 0;
93         fi->writectr = 0;
94         fi->orig_ino = 0;
95         fi->state = 0;
96         INIT_LIST_HEAD(&fi->write_files);
97         INIT_LIST_HEAD(&fi->queued_writes);
98         INIT_LIST_HEAD(&fi->writepages);
99         init_waitqueue_head(&fi->page_waitq);
100         fi->forget = fuse_alloc_forget();
101         if (!fi->forget) {
102                 kmem_cache_free(fuse_inode_cachep, inode);
103                 return NULL;
104         }
105
106         return inode;
107 }
108
109 static void fuse_i_callback(struct rcu_head *head)
110 {
111         struct inode *inode = container_of(head, struct inode, i_rcu);
112         kmem_cache_free(fuse_inode_cachep, inode);
113 }
114
115 static void fuse_destroy_inode(struct inode *inode)
116 {
117         struct fuse_inode *fi = get_fuse_inode(inode);
118         BUG_ON(!list_empty(&fi->write_files));
119         BUG_ON(!list_empty(&fi->queued_writes));
120         kfree(fi->forget);
121         call_rcu(&inode->i_rcu, fuse_i_callback);
122 }
123
124 static void fuse_evict_inode(struct inode *inode)
125 {
126         truncate_inode_pages(&inode->i_data, 0);
127         clear_inode(inode);
128         if (inode->i_sb->s_flags & MS_ACTIVE) {
129                 struct fuse_conn *fc = get_fuse_conn(inode);
130                 struct fuse_inode *fi = get_fuse_inode(inode);
131                 fuse_queue_forget(fc, fi->forget, fi->nodeid, fi->nlookup);
132                 fi->forget = NULL;
133         }
134 }
135
136 static int fuse_remount_fs(struct super_block *sb, int *flags, char *data)
137 {
138         if (*flags & MS_MANDLOCK)
139                 return -EINVAL;
140
141         return 0;
142 }
143
144 /*
145  * ino_t is 32-bits on 32-bit arch. We have to squash the 64-bit value down
146  * so that it will fit.
147  */
148 static ino_t fuse_squash_ino(u64 ino64)
149 {
150         ino_t ino = (ino_t) ino64;
151         if (sizeof(ino_t) < sizeof(u64))
152                 ino ^= ino64 >> (sizeof(u64) - sizeof(ino_t)) * 8;
153         return ino;
154 }
155
156 void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
157                                    u64 attr_valid)
158 {
159         struct fuse_conn *fc = get_fuse_conn(inode);
160         struct fuse_inode *fi = get_fuse_inode(inode);
161
162         fi->attr_version = ++fc->attr_version;
163         fi->i_time = attr_valid;
164
165         inode->i_ino     = fuse_squash_ino(attr->ino);
166         inode->i_mode    = (inode->i_mode & S_IFMT) | (attr->mode & 07777);
167         set_nlink(inode, attr->nlink);
168         inode->i_uid     = make_kuid(&init_user_ns, attr->uid);
169         inode->i_gid     = make_kgid(&init_user_ns, attr->gid);
170         inode->i_blocks  = attr->blocks;
171         inode->i_atime.tv_sec   = attr->atime;
172         inode->i_atime.tv_nsec  = attr->atimensec;
173         /* mtime from server may be stale due to local buffered write */
174         if (!fc->writeback_cache || !S_ISREG(inode->i_mode)) {
175                 inode->i_mtime.tv_sec   = attr->mtime;
176                 inode->i_mtime.tv_nsec  = attr->mtimensec;
177         }
178         inode->i_ctime.tv_sec   = attr->ctime;
179         inode->i_ctime.tv_nsec  = attr->ctimensec;
180
181         if (attr->blksize != 0)
182                 inode->i_blkbits = ilog2(attr->blksize);
183         else
184                 inode->i_blkbits = inode->i_sb->s_blocksize_bits;
185
186         /*
187          * Don't set the sticky bit in i_mode, unless we want the VFS
188          * to check permissions.  This prevents failures due to the
189          * check in may_delete().
190          */
191         fi->orig_i_mode = inode->i_mode;
192         if (!(fc->flags & FUSE_DEFAULT_PERMISSIONS))
193                 inode->i_mode &= ~S_ISVTX;
194
195         fi->orig_ino = attr->ino;
196 }
197
198 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
199                             u64 attr_valid, u64 attr_version)
200 {
201         struct fuse_conn *fc = get_fuse_conn(inode);
202         struct fuse_inode *fi = get_fuse_inode(inode);
203         bool is_wb = fc->writeback_cache;
204         loff_t oldsize;
205         struct timespec old_mtime;
206
207         spin_lock(&fc->lock);
208         if ((attr_version != 0 && fi->attr_version > attr_version) ||
209             test_bit(FUSE_I_SIZE_UNSTABLE, &fi->state)) {
210                 spin_unlock(&fc->lock);
211                 return;
212         }
213
214         old_mtime = inode->i_mtime;
215         fuse_change_attributes_common(inode, attr, attr_valid);
216
217         oldsize = inode->i_size;
218         /*
219          * In case of writeback_cache enabled, the cached writes beyond EOF
220          * extend local i_size without keeping userspace server in sync. So,
221          * attr->size coming from server can be stale. We cannot trust it.
222          */
223         if (!is_wb || !S_ISREG(inode->i_mode))
224                 i_size_write(inode, attr->size);
225         spin_unlock(&fc->lock);
226
227         if (!is_wb && S_ISREG(inode->i_mode)) {
228                 bool inval = false;
229
230                 if (oldsize != attr->size) {
231                         truncate_pagecache(inode, attr->size);
232                         inval = true;
233                 } else if (fc->auto_inval_data) {
234                         struct timespec new_mtime = {
235                                 .tv_sec = attr->mtime,
236                                 .tv_nsec = attr->mtimensec,
237                         };
238
239                         /*
240                          * Auto inval mode also checks and invalidates if mtime
241                          * has changed.
242                          */
243                         if (!timespec_equal(&old_mtime, &new_mtime))
244                                 inval = true;
245                 }
246
247                 if (inval)
248                         invalidate_inode_pages2(inode->i_mapping);
249         }
250 }
251
252 static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
253 {
254         inode->i_mode = attr->mode & S_IFMT;
255         inode->i_size = attr->size;
256         inode->i_mtime.tv_sec  = attr->mtime;
257         inode->i_mtime.tv_nsec = attr->mtimensec;
258         if (S_ISREG(inode->i_mode)) {
259                 fuse_init_common(inode);
260                 fuse_init_file_inode(inode);
261         } else if (S_ISDIR(inode->i_mode))
262                 fuse_init_dir(inode);
263         else if (S_ISLNK(inode->i_mode))
264                 fuse_init_symlink(inode);
265         else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
266                  S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
267                 fuse_init_common(inode);
268                 init_special_inode(inode, inode->i_mode,
269                                    new_decode_dev(attr->rdev));
270         } else
271                 BUG();
272 }
273
274 int fuse_inode_eq(struct inode *inode, void *_nodeidp)
275 {
276         u64 nodeid = *(u64 *) _nodeidp;
277         if (get_node_id(inode) == nodeid)
278                 return 1;
279         else
280                 return 0;
281 }
282
283 static int fuse_inode_set(struct inode *inode, void *_nodeidp)
284 {
285         u64 nodeid = *(u64 *) _nodeidp;
286         get_fuse_inode(inode)->nodeid = nodeid;
287         return 0;
288 }
289
290 struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
291                         int generation, struct fuse_attr *attr,
292                         u64 attr_valid, u64 attr_version)
293 {
294         struct inode *inode;
295         struct fuse_inode *fi;
296         struct fuse_conn *fc = get_fuse_conn_super(sb);
297
298  retry:
299         inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);
300         if (!inode)
301                 return NULL;
302
303         if ((inode->i_state & I_NEW)) {
304                 inode->i_flags |= S_NOATIME;
305                 if (!fc->writeback_cache || !S_ISREG(inode->i_mode))
306                         inode->i_flags |= S_NOCMTIME;
307                 inode->i_generation = generation;
308                 inode->i_data.backing_dev_info = &fc->bdi;
309                 fuse_init_inode(inode, attr);
310                 unlock_new_inode(inode);
311         } else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
312                 /* Inode has changed type, any I/O on the old should fail */
313                 make_bad_inode(inode);
314                 iput(inode);
315                 goto retry;
316         }
317
318         fi = get_fuse_inode(inode);
319         spin_lock(&fc->lock);
320         fi->nlookup++;
321         spin_unlock(&fc->lock);
322         fuse_change_attributes(inode, attr, attr_valid, attr_version);
323
324         return inode;
325 }
326
327 int fuse_reverse_inval_inode(struct super_block *sb, u64 nodeid,
328                              loff_t offset, loff_t len)
329 {
330         struct inode *inode;
331         pgoff_t pg_start;
332         pgoff_t pg_end;
333
334         inode = ilookup5(sb, nodeid, fuse_inode_eq, &nodeid);
335         if (!inode)
336                 return -ENOENT;
337
338         fuse_invalidate_attr(inode);
339         if (offset >= 0) {
340                 pg_start = offset >> PAGE_CACHE_SHIFT;
341                 if (len <= 0)
342                         pg_end = -1;
343                 else
344                         pg_end = (offset + len - 1) >> PAGE_CACHE_SHIFT;
345                 invalidate_inode_pages2_range(inode->i_mapping,
346                                               pg_start, pg_end);
347         }
348         iput(inode);
349         return 0;
350 }
351
352 static void fuse_umount_begin(struct super_block *sb)
353 {
354         fuse_abort_conn(get_fuse_conn_super(sb));
355 }
356
357 static void fuse_send_destroy(struct fuse_conn *fc)
358 {
359         struct fuse_req *req = fc->destroy_req;
360         if (req && fc->conn_init) {
361                 fc->destroy_req = NULL;
362                 req->in.h.opcode = FUSE_DESTROY;
363                 req->force = 1;
364                 req->background = 0;
365                 fuse_request_send(fc, req);
366                 fuse_put_request(fc, req);
367         }
368 }
369
370 static void fuse_bdi_destroy(struct fuse_conn *fc)
371 {
372         if (fc->bdi_initialized)
373                 bdi_destroy(&fc->bdi);
374 }
375
376 void fuse_conn_kill(struct fuse_conn *fc)
377 {
378         spin_lock(&fc->lock);
379         fc->connected = 0;
380         fc->blocked = 0;
381         fc->initialized = 1;
382         spin_unlock(&fc->lock);
383         /* Flush all readers on this fs */
384         kill_fasync(&fc->fasync, SIGIO, POLL_IN);
385         wake_up_all(&fc->waitq);
386         wake_up_all(&fc->blocked_waitq);
387         wake_up_all(&fc->reserved_req_waitq);
388 }
389 EXPORT_SYMBOL_GPL(fuse_conn_kill);
390
391 static void fuse_put_super(struct super_block *sb)
392 {
393         struct fuse_conn *fc = get_fuse_conn_super(sb);
394
395         fuse_send_destroy(fc);
396
397         fuse_conn_kill(fc);
398         mutex_lock(&fuse_mutex);
399         list_del(&fc->entry);
400         fuse_ctl_remove_conn(fc);
401         mutex_unlock(&fuse_mutex);
402         fuse_bdi_destroy(fc);
403
404         fuse_conn_put(fc);
405 }
406
407 static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
408 {
409         stbuf->f_type    = FUSE_SUPER_MAGIC;
410         stbuf->f_bsize   = attr->bsize;
411         stbuf->f_frsize  = attr->frsize;
412         stbuf->f_blocks  = attr->blocks;
413         stbuf->f_bfree   = attr->bfree;
414         stbuf->f_bavail  = attr->bavail;
415         stbuf->f_files   = attr->files;
416         stbuf->f_ffree   = attr->ffree;
417         stbuf->f_namelen = attr->namelen;
418         /* fsid is left zero */
419 }
420
421 static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)
422 {
423         struct super_block *sb = dentry->d_sb;
424         struct fuse_conn *fc = get_fuse_conn_super(sb);
425         struct fuse_req *req;
426         struct fuse_statfs_out outarg;
427         int err;
428
429         if (!fuse_allow_current_process(fc)) {
430                 buf->f_type = FUSE_SUPER_MAGIC;
431                 return 0;
432         }
433
434         req = fuse_get_req_nopages(fc);
435         if (IS_ERR(req))
436                 return PTR_ERR(req);
437
438         memset(&outarg, 0, sizeof(outarg));
439         req->in.numargs = 0;
440         req->in.h.opcode = FUSE_STATFS;
441         req->in.h.nodeid = get_node_id(dentry->d_inode);
442         req->out.numargs = 1;
443         req->out.args[0].size =
444                 fc->minor < 4 ? FUSE_COMPAT_STATFS_SIZE : sizeof(outarg);
445         req->out.args[0].value = &outarg;
446         fuse_request_send(fc, req);
447         err = req->out.h.error;
448         if (!err)
449                 convert_fuse_statfs(buf, &outarg.st);
450         fuse_put_request(fc, req);
451         return err;
452 }
453
454 enum {
455         OPT_FD,
456         OPT_ROOTMODE,
457         OPT_USER_ID,
458         OPT_GROUP_ID,
459         OPT_DEFAULT_PERMISSIONS,
460         OPT_ALLOW_OTHER,
461         OPT_MAX_READ,
462         OPT_BLKSIZE,
463         OPT_ERR
464 };
465
466 static const match_table_t tokens = {
467         {OPT_FD,                        "fd=%u"},
468         {OPT_ROOTMODE,                  "rootmode=%o"},
469         {OPT_USER_ID,                   "user_id=%u"},
470         {OPT_GROUP_ID,                  "group_id=%u"},
471         {OPT_DEFAULT_PERMISSIONS,       "default_permissions"},
472         {OPT_ALLOW_OTHER,               "allow_other"},
473         {OPT_MAX_READ,                  "max_read=%u"},
474         {OPT_BLKSIZE,                   "blksize=%u"},
475         {OPT_ERR,                       NULL}
476 };
477
478 static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev)
479 {
480         char *p;
481         memset(d, 0, sizeof(struct fuse_mount_data));
482         d->max_read = ~0;
483         d->blksize = FUSE_DEFAULT_BLKSIZE;
484
485         while ((p = strsep(&opt, ",")) != NULL) {
486                 int token;
487                 int value;
488                 substring_t args[MAX_OPT_ARGS];
489                 if (!*p)
490                         continue;
491
492                 token = match_token(p, tokens, args);
493                 switch (token) {
494                 case OPT_FD:
495                         if (match_int(&args[0], &value))
496                                 return 0;
497                         d->fd = value;
498                         d->fd_present = 1;
499                         break;
500
501                 case OPT_ROOTMODE:
502                         if (match_octal(&args[0], &value))
503                                 return 0;
504                         if (!fuse_valid_type(value))
505                                 return 0;
506                         d->rootmode = value;
507                         d->rootmode_present = 1;
508                         break;
509
510                 case OPT_USER_ID:
511                         if (match_int(&args[0], &value))
512                                 return 0;
513                         d->user_id = make_kuid(current_user_ns(), value);
514                         if (!uid_valid(d->user_id))
515                                 return 0;
516                         d->user_id_present = 1;
517                         break;
518
519                 case OPT_GROUP_ID:
520                         if (match_int(&args[0], &value))
521                                 return 0;
522                         d->group_id = make_kgid(current_user_ns(), value);
523                         if (!gid_valid(d->group_id))
524                                 return 0;
525                         d->group_id_present = 1;
526                         break;
527
528                 case OPT_DEFAULT_PERMISSIONS:
529                         d->flags |= FUSE_DEFAULT_PERMISSIONS;
530                         break;
531
532                 case OPT_ALLOW_OTHER:
533                         d->flags |= FUSE_ALLOW_OTHER;
534                         break;
535
536                 case OPT_MAX_READ:
537                         if (match_int(&args[0], &value))
538                                 return 0;
539                         d->max_read = value;
540                         break;
541
542                 case OPT_BLKSIZE:
543                         if (!is_bdev || match_int(&args[0], &value))
544                                 return 0;
545                         d->blksize = value;
546                         break;
547
548                 default:
549                         return 0;
550                 }
551         }
552
553         if (!d->fd_present || !d->rootmode_present ||
554             !d->user_id_present || !d->group_id_present)
555                 return 0;
556
557         return 1;
558 }
559
560 static int fuse_show_options(struct seq_file *m, struct dentry *root)
561 {
562         struct super_block *sb = root->d_sb;
563         struct fuse_conn *fc = get_fuse_conn_super(sb);
564
565         seq_printf(m, ",user_id=%u", from_kuid_munged(&init_user_ns, fc->user_id));
566         seq_printf(m, ",group_id=%u", from_kgid_munged(&init_user_ns, fc->group_id));
567         if (fc->flags & FUSE_DEFAULT_PERMISSIONS)
568                 seq_puts(m, ",default_permissions");
569         if (fc->flags & FUSE_ALLOW_OTHER)
570                 seq_puts(m, ",allow_other");
571         if (fc->max_read != ~0)
572                 seq_printf(m, ",max_read=%u", fc->max_read);
573         if (sb->s_bdev && sb->s_blocksize != FUSE_DEFAULT_BLKSIZE)
574                 seq_printf(m, ",blksize=%lu", sb->s_blocksize);
575         return 0;
576 }
577
578 void fuse_conn_init(struct fuse_conn *fc)
579 {
580         memset(fc, 0, sizeof(*fc));
581         spin_lock_init(&fc->lock);
582         init_rwsem(&fc->killsb);
583         atomic_set(&fc->count, 1);
584         init_waitqueue_head(&fc->waitq);
585         init_waitqueue_head(&fc->blocked_waitq);
586         init_waitqueue_head(&fc->reserved_req_waitq);
587         INIT_LIST_HEAD(&fc->pending);
588         INIT_LIST_HEAD(&fc->processing);
589         INIT_LIST_HEAD(&fc->io);
590         INIT_LIST_HEAD(&fc->interrupts);
591         INIT_LIST_HEAD(&fc->bg_queue);
592         INIT_LIST_HEAD(&fc->entry);
593         fc->forget_list_tail = &fc->forget_list_head;
594         atomic_set(&fc->num_waiting, 0);
595         fc->max_background = FUSE_DEFAULT_MAX_BACKGROUND;
596         fc->congestion_threshold = FUSE_DEFAULT_CONGESTION_THRESHOLD;
597         fc->khctr = 0;
598         fc->polled_files = RB_ROOT;
599         fc->reqctr = 0;
600         fc->blocked = 0;
601         fc->initialized = 0;
602         fc->attr_version = 1;
603         get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));
604 }
605 EXPORT_SYMBOL_GPL(fuse_conn_init);
606
607 void fuse_conn_put(struct fuse_conn *fc)
608 {
609         if (atomic_dec_and_test(&fc->count)) {
610                 if (fc->destroy_req)
611                         fuse_request_free(fc->destroy_req);
612                 fc->release(fc);
613         }
614 }
615 EXPORT_SYMBOL_GPL(fuse_conn_put);
616
617 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc)
618 {
619         atomic_inc(&fc->count);
620         return fc;
621 }
622 EXPORT_SYMBOL_GPL(fuse_conn_get);
623
624 static struct inode *fuse_get_root_inode(struct super_block *sb, unsigned mode)
625 {
626         struct fuse_attr attr;
627         memset(&attr, 0, sizeof(attr));
628
629         attr.mode = mode;
630         attr.ino = FUSE_ROOT_ID;
631         attr.nlink = 1;
632         return fuse_iget(sb, 1, 0, &attr, 0, 0);
633 }
634
635 struct fuse_inode_handle {
636         u64 nodeid;
637         u32 generation;
638 };
639
640 static struct dentry *fuse_get_dentry(struct super_block *sb,
641                                       struct fuse_inode_handle *handle)
642 {
643         struct fuse_conn *fc = get_fuse_conn_super(sb);
644         struct inode *inode;
645         struct dentry *entry;
646         int err = -ESTALE;
647
648         if (handle->nodeid == 0)
649                 goto out_err;
650
651         inode = ilookup5(sb, handle->nodeid, fuse_inode_eq, &handle->nodeid);
652         if (!inode) {
653                 struct fuse_entry_out outarg;
654                 struct qstr name;
655
656                 if (!fc->export_support)
657                         goto out_err;
658
659                 name.len = 1;
660                 name.name = ".";
661                 err = fuse_lookup_name(sb, handle->nodeid, &name, &outarg,
662                                        &inode);
663                 if (err && err != -ENOENT)
664                         goto out_err;
665                 if (err || !inode) {
666                         err = -ESTALE;
667                         goto out_err;
668                 }
669                 err = -EIO;
670                 if (get_node_id(inode) != handle->nodeid)
671                         goto out_iput;
672         }
673         err = -ESTALE;
674         if (inode->i_generation != handle->generation)
675                 goto out_iput;
676
677         entry = d_obtain_alias(inode);
678         if (!IS_ERR(entry) && get_node_id(inode) != FUSE_ROOT_ID)
679                 fuse_invalidate_entry_cache(entry);
680
681         return entry;
682
683  out_iput:
684         iput(inode);
685  out_err:
686         return ERR_PTR(err);
687 }
688
689 static int fuse_encode_fh(struct inode *inode, u32 *fh, int *max_len,
690                            struct inode *parent)
691 {
692         int len = parent ? 6 : 3;
693         u64 nodeid;
694         u32 generation;
695
696         if (*max_len < len) {
697                 *max_len = len;
698                 return  FILEID_INVALID;
699         }
700
701         nodeid = get_fuse_inode(inode)->nodeid;
702         generation = inode->i_generation;
703
704         fh[0] = (u32)(nodeid >> 32);
705         fh[1] = (u32)(nodeid & 0xffffffff);
706         fh[2] = generation;
707
708         if (parent) {
709                 nodeid = get_fuse_inode(parent)->nodeid;
710                 generation = parent->i_generation;
711
712                 fh[3] = (u32)(nodeid >> 32);
713                 fh[4] = (u32)(nodeid & 0xffffffff);
714                 fh[5] = generation;
715         }
716
717         *max_len = len;
718         return parent ? 0x82 : 0x81;
719 }
720
721 static struct dentry *fuse_fh_to_dentry(struct super_block *sb,
722                 struct fid *fid, int fh_len, int fh_type)
723 {
724         struct fuse_inode_handle handle;
725
726         if ((fh_type != 0x81 && fh_type != 0x82) || fh_len < 3)
727                 return NULL;
728
729         handle.nodeid = (u64) fid->raw[0] << 32;
730         handle.nodeid |= (u64) fid->raw[1];
731         handle.generation = fid->raw[2];
732         return fuse_get_dentry(sb, &handle);
733 }
734
735 static struct dentry *fuse_fh_to_parent(struct super_block *sb,
736                 struct fid *fid, int fh_len, int fh_type)
737 {
738         struct fuse_inode_handle parent;
739
740         if (fh_type != 0x82 || fh_len < 6)
741                 return NULL;
742
743         parent.nodeid = (u64) fid->raw[3] << 32;
744         parent.nodeid |= (u64) fid->raw[4];
745         parent.generation = fid->raw[5];
746         return fuse_get_dentry(sb, &parent);
747 }
748
749 static struct dentry *fuse_get_parent(struct dentry *child)
750 {
751         struct inode *child_inode = child->d_inode;
752         struct fuse_conn *fc = get_fuse_conn(child_inode);
753         struct inode *inode;
754         struct dentry *parent;
755         struct fuse_entry_out outarg;
756         struct qstr name;
757         int err;
758
759         if (!fc->export_support)
760                 return ERR_PTR(-ESTALE);
761
762         name.len = 2;
763         name.name = "..";
764         err = fuse_lookup_name(child_inode->i_sb, get_node_id(child_inode),
765                                &name, &outarg, &inode);
766         if (err) {
767                 if (err == -ENOENT)
768                         return ERR_PTR(-ESTALE);
769                 return ERR_PTR(err);
770         }
771
772         parent = d_obtain_alias(inode);
773         if (!IS_ERR(parent) && get_node_id(inode) != FUSE_ROOT_ID)
774                 fuse_invalidate_entry_cache(parent);
775
776         return parent;
777 }
778
779 static const struct export_operations fuse_export_operations = {
780         .fh_to_dentry   = fuse_fh_to_dentry,
781         .fh_to_parent   = fuse_fh_to_parent,
782         .encode_fh      = fuse_encode_fh,
783         .get_parent     = fuse_get_parent,
784 };
785
786 static const struct super_operations fuse_super_operations = {
787         .alloc_inode    = fuse_alloc_inode,
788         .destroy_inode  = fuse_destroy_inode,
789         .evict_inode    = fuse_evict_inode,
790         .drop_inode     = generic_delete_inode,
791         .remount_fs     = fuse_remount_fs,
792         .put_super      = fuse_put_super,
793         .umount_begin   = fuse_umount_begin,
794         .statfs         = fuse_statfs,
795         .show_options   = fuse_show_options,
796 };
797
798 static void sanitize_global_limit(unsigned *limit)
799 {
800         if (*limit == 0)
801                 *limit = ((totalram_pages << PAGE_SHIFT) >> 13) /
802                          sizeof(struct fuse_req);
803
804         if (*limit >= 1 << 16)
805                 *limit = (1 << 16) - 1;
806 }
807
808 static int set_global_limit(const char *val, struct kernel_param *kp)
809 {
810         int rv;
811
812         rv = param_set_uint(val, kp);
813         if (rv)
814                 return rv;
815
816         sanitize_global_limit((unsigned *)kp->arg);
817
818         return 0;
819 }
820
821 static void process_init_limits(struct fuse_conn *fc, struct fuse_init_out *arg)
822 {
823         int cap_sys_admin = capable(CAP_SYS_ADMIN);
824
825         if (arg->minor < 13)
826                 return;
827
828         sanitize_global_limit(&max_user_bgreq);
829         sanitize_global_limit(&max_user_congthresh);
830
831         if (arg->max_background) {
832                 fc->max_background = arg->max_background;
833
834                 if (!cap_sys_admin && fc->max_background > max_user_bgreq)
835                         fc->max_background = max_user_bgreq;
836         }
837         if (arg->congestion_threshold) {
838                 fc->congestion_threshold = arg->congestion_threshold;
839
840                 if (!cap_sys_admin &&
841                     fc->congestion_threshold > max_user_congthresh)
842                         fc->congestion_threshold = max_user_congthresh;
843         }
844 }
845
846 static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
847 {
848         struct fuse_init_out *arg = &req->misc.init_out;
849
850         if (req->out.h.error || arg->major != FUSE_KERNEL_VERSION)
851                 fc->conn_error = 1;
852         else {
853                 unsigned long ra_pages;
854
855                 process_init_limits(fc, arg);
856
857                 if (arg->minor >= 6) {
858                         ra_pages = arg->max_readahead / PAGE_CACHE_SIZE;
859                         if (arg->flags & FUSE_ASYNC_READ)
860                                 fc->async_read = 1;
861                         if (!(arg->flags & FUSE_POSIX_LOCKS))
862                                 fc->no_lock = 1;
863                         if (arg->minor >= 17) {
864                                 if (!(arg->flags & FUSE_FLOCK_LOCKS))
865                                         fc->no_flock = 1;
866                         } else {
867                                 if (!(arg->flags & FUSE_POSIX_LOCKS))
868                                         fc->no_flock = 1;
869                         }
870                         if (arg->flags & FUSE_ATOMIC_O_TRUNC)
871                                 fc->atomic_o_trunc = 1;
872                         if (arg->minor >= 9) {
873                                 /* LOOKUP has dependency on proto version */
874                                 if (arg->flags & FUSE_EXPORT_SUPPORT)
875                                         fc->export_support = 1;
876                         }
877                         if (arg->flags & FUSE_BIG_WRITES)
878                                 fc->big_writes = 1;
879                         if (arg->flags & FUSE_DONT_MASK)
880                                 fc->dont_mask = 1;
881                         if (arg->flags & FUSE_AUTO_INVAL_DATA)
882                                 fc->auto_inval_data = 1;
883                         if (arg->flags & FUSE_DO_READDIRPLUS) {
884                                 fc->do_readdirplus = 1;
885                                 if (arg->flags & FUSE_READDIRPLUS_AUTO)
886                                         fc->readdirplus_auto = 1;
887                         }
888                         if (arg->flags & FUSE_ASYNC_DIO)
889                                 fc->async_dio = 1;
890                 } else {
891                         ra_pages = fc->max_read / PAGE_CACHE_SIZE;
892                         fc->no_lock = 1;
893                         fc->no_flock = 1;
894                 }
895
896                 fc->bdi.ra_pages = min(fc->bdi.ra_pages, ra_pages);
897                 fc->minor = arg->minor;
898                 fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
899                 fc->max_write = max_t(unsigned, 4096, fc->max_write);
900                 fc->conn_init = 1;
901         }
902         fc->initialized = 1;
903         wake_up_all(&fc->blocked_waitq);
904 }
905
906 static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
907 {
908         struct fuse_init_in *arg = &req->misc.init_in;
909
910         arg->major = FUSE_KERNEL_VERSION;
911         arg->minor = FUSE_KERNEL_MINOR_VERSION;
912         arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
913         arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |
914                 FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES | FUSE_DONT_MASK |
915                 FUSE_SPLICE_WRITE | FUSE_SPLICE_MOVE | FUSE_SPLICE_READ |
916                 FUSE_FLOCK_LOCKS | FUSE_IOCTL_DIR | FUSE_AUTO_INVAL_DATA |
917                 FUSE_DO_READDIRPLUS | FUSE_READDIRPLUS_AUTO | FUSE_ASYNC_DIO;
918         req->in.h.opcode = FUSE_INIT;
919         req->in.numargs = 1;
920         req->in.args[0].size = sizeof(*arg);
921         req->in.args[0].value = arg;
922         req->out.numargs = 1;
923         /* Variable length argument used for backward compatibility
924            with interface version < 7.5.  Rest of init_out is zeroed
925            by do_get_request(), so a short reply is not a problem */
926         req->out.argvar = 1;
927         req->out.args[0].size = sizeof(struct fuse_init_out);
928         req->out.args[0].value = &req->misc.init_out;
929         req->end = process_init_reply;
930         fuse_request_send_background(fc, req);
931 }
932
933 static void fuse_free_conn(struct fuse_conn *fc)
934 {
935         kfree_rcu(fc, rcu);
936 }
937
938 static int fuse_bdi_init(struct fuse_conn *fc, struct super_block *sb)
939 {
940         int err;
941
942         fc->bdi.name = "fuse";
943         fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
944         /* fuse does it's own writeback accounting */
945         fc->bdi.capabilities = BDI_CAP_NO_ACCT_WB | BDI_CAP_STRICTLIMIT;
946
947         err = bdi_init(&fc->bdi);
948         if (err)
949                 return err;
950
951         fc->bdi_initialized = 1;
952
953         if (sb->s_bdev) {
954                 err =  bdi_register(&fc->bdi, NULL, "%u:%u-fuseblk",
955                                     MAJOR(fc->dev), MINOR(fc->dev));
956         } else {
957                 err = bdi_register_dev(&fc->bdi, fc->dev);
958         }
959
960         if (err)
961                 return err;
962
963         /*
964          * For a single fuse filesystem use max 1% of dirty +
965          * writeback threshold.
966          *
967          * This gives about 1M of write buffer for memory maps on a
968          * machine with 1G and 10% dirty_ratio, which should be more
969          * than enough.
970          *
971          * Privileged users can raise it by writing to
972          *
973          *    /sys/class/bdi/<bdi>/max_ratio
974          */
975         bdi_set_max_ratio(&fc->bdi, 1);
976
977         return 0;
978 }
979
980 static int fuse_fill_super(struct super_block *sb, void *data, int silent)
981 {
982         struct fuse_conn *fc;
983         struct inode *root;
984         struct fuse_mount_data d;
985         struct file *file;
986         struct dentry *root_dentry;
987         struct fuse_req *init_req;
988         int err;
989         int is_bdev = sb->s_bdev != NULL;
990
991         err = -EINVAL;
992         if (sb->s_flags & MS_MANDLOCK)
993                 goto err;
994
995         sb->s_flags &= ~MS_NOSEC;
996
997         if (!parse_fuse_opt((char *) data, &d, is_bdev))
998                 goto err;
999
1000         if (is_bdev) {
1001 #ifdef CONFIG_BLOCK
1002                 err = -EINVAL;
1003                 if (!sb_set_blocksize(sb, d.blksize))
1004                         goto err;
1005 #endif
1006         } else {
1007                 sb->s_blocksize = PAGE_CACHE_SIZE;
1008                 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
1009         }
1010         sb->s_magic = FUSE_SUPER_MAGIC;
1011         sb->s_op = &fuse_super_operations;
1012         sb->s_maxbytes = MAX_LFS_FILESIZE;
1013         sb->s_time_gran = 1;
1014         sb->s_export_op = &fuse_export_operations;
1015
1016         file = fget(d.fd);
1017         err = -EINVAL;
1018         if (!file)
1019                 goto err;
1020
1021         if ((file->f_op != &fuse_dev_operations) ||
1022             (file->f_cred->user_ns != &init_user_ns))
1023                 goto err_fput;
1024
1025         fc = kmalloc(sizeof(*fc), GFP_KERNEL);
1026         err = -ENOMEM;
1027         if (!fc)
1028                 goto err_fput;
1029
1030         fuse_conn_init(fc);
1031
1032         fc->dev = sb->s_dev;
1033         fc->sb = sb;
1034         err = fuse_bdi_init(fc, sb);
1035         if (err)
1036                 goto err_put_conn;
1037
1038         sb->s_bdi = &fc->bdi;
1039
1040         /* Handle umasking inside the fuse code */
1041         if (sb->s_flags & MS_POSIXACL)
1042                 fc->dont_mask = 1;
1043         sb->s_flags |= MS_POSIXACL;
1044
1045         fc->release = fuse_free_conn;
1046         fc->flags = d.flags;
1047         fc->user_id = d.user_id;
1048         fc->group_id = d.group_id;
1049         fc->max_read = max_t(unsigned, 4096, d.max_read);
1050
1051         /* Used by get_root_inode() */
1052         sb->s_fs_info = fc;
1053
1054         err = -ENOMEM;
1055         root = fuse_get_root_inode(sb, d.rootmode);
1056         root_dentry = d_make_root(root);
1057         if (!root_dentry)
1058                 goto err_put_conn;
1059         /* only now - we want root dentry with NULL ->d_op */
1060         sb->s_d_op = &fuse_dentry_operations;
1061
1062         init_req = fuse_request_alloc(0);
1063         if (!init_req)
1064                 goto err_put_root;
1065         init_req->background = 1;
1066
1067         if (is_bdev) {
1068                 fc->destroy_req = fuse_request_alloc(0);
1069                 if (!fc->destroy_req)
1070                         goto err_free_init_req;
1071         }
1072
1073         mutex_lock(&fuse_mutex);
1074         err = -EINVAL;
1075         if (file->private_data)
1076                 goto err_unlock;
1077
1078         err = fuse_ctl_add_conn(fc);
1079         if (err)
1080                 goto err_unlock;
1081
1082         list_add_tail(&fc->entry, &fuse_conn_list);
1083         sb->s_root = root_dentry;
1084         fc->connected = 1;
1085         file->private_data = fuse_conn_get(fc);
1086         mutex_unlock(&fuse_mutex);
1087         /*
1088          * atomic_dec_and_test() in fput() provides the necessary
1089          * memory barrier for file->private_data to be visible on all
1090          * CPUs after this
1091          */
1092         fput(file);
1093
1094         fuse_send_init(fc, init_req);
1095
1096         return 0;
1097
1098  err_unlock:
1099         mutex_unlock(&fuse_mutex);
1100  err_free_init_req:
1101         fuse_request_free(init_req);
1102  err_put_root:
1103         dput(root_dentry);
1104  err_put_conn:
1105         fuse_bdi_destroy(fc);
1106         fuse_conn_put(fc);
1107  err_fput:
1108         fput(file);
1109  err:
1110         return err;
1111 }
1112
1113 static struct dentry *fuse_mount(struct file_system_type *fs_type,
1114                        int flags, const char *dev_name,
1115                        void *raw_data)
1116 {
1117         return mount_nodev(fs_type, flags, raw_data, fuse_fill_super);
1118 }
1119
1120 static void fuse_kill_sb_anon(struct super_block *sb)
1121 {
1122         struct fuse_conn *fc = get_fuse_conn_super(sb);
1123
1124         if (fc) {
1125                 down_write(&fc->killsb);
1126                 fc->sb = NULL;
1127                 up_write(&fc->killsb);
1128         }
1129
1130         kill_anon_super(sb);
1131 }
1132
1133 static struct file_system_type fuse_fs_type = {
1134         .owner          = THIS_MODULE,
1135         .name           = "fuse",
1136         .fs_flags       = FS_HAS_SUBTYPE,
1137         .mount          = fuse_mount,
1138         .kill_sb        = fuse_kill_sb_anon,
1139 };
1140 MODULE_ALIAS_FS("fuse");
1141
1142 #ifdef CONFIG_BLOCK
1143 static struct dentry *fuse_mount_blk(struct file_system_type *fs_type,
1144                            int flags, const char *dev_name,
1145                            void *raw_data)
1146 {
1147         return mount_bdev(fs_type, flags, dev_name, raw_data, fuse_fill_super);
1148 }
1149
1150 static void fuse_kill_sb_blk(struct super_block *sb)
1151 {
1152         struct fuse_conn *fc = get_fuse_conn_super(sb);
1153
1154         if (fc) {
1155                 down_write(&fc->killsb);
1156                 fc->sb = NULL;
1157                 up_write(&fc->killsb);
1158         }
1159
1160         kill_block_super(sb);
1161 }
1162
1163 static struct file_system_type fuseblk_fs_type = {
1164         .owner          = THIS_MODULE,
1165         .name           = "fuseblk",
1166         .mount          = fuse_mount_blk,
1167         .kill_sb        = fuse_kill_sb_blk,
1168         .fs_flags       = FS_REQUIRES_DEV | FS_HAS_SUBTYPE,
1169 };
1170 MODULE_ALIAS_FS("fuseblk");
1171
1172 static inline int register_fuseblk(void)
1173 {
1174         return register_filesystem(&fuseblk_fs_type);
1175 }
1176
1177 static inline void unregister_fuseblk(void)
1178 {
1179         unregister_filesystem(&fuseblk_fs_type);
1180 }
1181 #else
1182 static inline int register_fuseblk(void)
1183 {
1184         return 0;
1185 }
1186
1187 static inline void unregister_fuseblk(void)
1188 {
1189 }
1190 #endif
1191
1192 static void fuse_inode_init_once(void *foo)
1193 {
1194         struct inode *inode = foo;
1195
1196         inode_init_once(inode);
1197 }
1198
1199 static int __init fuse_fs_init(void)
1200 {
1201         int err;
1202
1203         fuse_inode_cachep = kmem_cache_create("fuse_inode",
1204                                               sizeof(struct fuse_inode),
1205                                               0, SLAB_HWCACHE_ALIGN,
1206                                               fuse_inode_init_once);
1207         err = -ENOMEM;
1208         if (!fuse_inode_cachep)
1209                 goto out;
1210
1211         err = register_fuseblk();
1212         if (err)
1213                 goto out2;
1214
1215         err = register_filesystem(&fuse_fs_type);
1216         if (err)
1217                 goto out3;
1218
1219         return 0;
1220
1221  out3:
1222         unregister_fuseblk();
1223  out2:
1224         kmem_cache_destroy(fuse_inode_cachep);
1225  out:
1226         return err;
1227 }
1228
1229 static void fuse_fs_cleanup(void)
1230 {
1231         unregister_filesystem(&fuse_fs_type);
1232         unregister_fuseblk();
1233
1234         /*
1235          * Make sure all delayed rcu free inodes are flushed before we
1236          * destroy cache.
1237          */
1238         rcu_barrier();
1239         kmem_cache_destroy(fuse_inode_cachep);
1240 }
1241
1242 static struct kobject *fuse_kobj;
1243 static struct kobject *connections_kobj;
1244
1245 static int fuse_sysfs_init(void)
1246 {
1247         int err;
1248
1249         fuse_kobj = kobject_create_and_add("fuse", fs_kobj);
1250         if (!fuse_kobj) {
1251                 err = -ENOMEM;
1252                 goto out_err;
1253         }
1254
1255         connections_kobj = kobject_create_and_add("connections", fuse_kobj);
1256         if (!connections_kobj) {
1257                 err = -ENOMEM;
1258                 goto out_fuse_unregister;
1259         }
1260
1261         return 0;
1262
1263  out_fuse_unregister:
1264         kobject_put(fuse_kobj);
1265  out_err:
1266         return err;
1267 }
1268
1269 static void fuse_sysfs_cleanup(void)
1270 {
1271         kobject_put(connections_kobj);
1272         kobject_put(fuse_kobj);
1273 }
1274
1275 static int __init fuse_init(void)
1276 {
1277         int res;
1278
1279         printk(KERN_INFO "fuse init (API version %i.%i)\n",
1280                FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
1281
1282         INIT_LIST_HEAD(&fuse_conn_list);
1283         res = fuse_fs_init();
1284         if (res)
1285                 goto err;
1286
1287         res = fuse_dev_init();
1288         if (res)
1289                 goto err_fs_cleanup;
1290
1291         res = fuse_sysfs_init();
1292         if (res)
1293                 goto err_dev_cleanup;
1294
1295         res = fuse_ctl_init();
1296         if (res)
1297                 goto err_sysfs_cleanup;
1298
1299         sanitize_global_limit(&max_user_bgreq);
1300         sanitize_global_limit(&max_user_congthresh);
1301
1302         return 0;
1303
1304  err_sysfs_cleanup:
1305         fuse_sysfs_cleanup();
1306  err_dev_cleanup:
1307         fuse_dev_cleanup();
1308  err_fs_cleanup:
1309         fuse_fs_cleanup();
1310  err:
1311         return res;
1312 }
1313
1314 static void __exit fuse_exit(void)
1315 {
1316         printk(KERN_DEBUG "fuse exit\n");
1317
1318         fuse_ctl_cleanup();
1319         fuse_sysfs_cleanup();
1320         fuse_fs_cleanup();
1321         fuse_dev_cleanup();
1322 }
1323
1324 module_init(fuse_init);
1325 module_exit(fuse_exit);