fs/fuse/inode.c

   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/fs_context.h>
  19 #include <linux/fs_parser.h>
  20 #include <linux/statfs.h>
  21 #include <linux/random.h>
  22 #include <linux/sched.h>
  23 #include <linux/exportfs.h>
  24 #include <linux/posix_acl.h>
  25 #include <linux/pid_namespace.h>
  26
  27 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
  28 MODULE_DESCRIPTION("Filesystem in Userspace");
  29 MODULE_LICENSE("GPL");
  30
  31 static struct kmem_cache *fuse_inode_cachep;
  32 struct list_head fuse_conn_list;
  33 DEFINE_MUTEX(fuse_mutex);
  34
  35 static int set_global_limit(const char *val, const struct kernel_param *kp);
  36
  37 unsigned max_user_bgreq;
  38 module_param_call(max_user_bgreq, set_global_limit, param_get_uint,
  39                   &max_user_bgreq, 0644);
  40 __MODULE_PARM_TYPE(max_user_bgreq, "uint");
  41 MODULE_PARM_DESC(max_user_bgreq,
  42  "Global limit for the maximum number of backgrounded requests an "
  43  "unprivileged user can set");
  44
  45 unsigned max_user_congthresh;
  46 module_param_call(max_user_congthresh, set_global_limit, param_get_uint,
  47                   &max_user_congthresh, 0644);
  48 __MODULE_PARM_TYPE(max_user_congthresh, "uint");
  49 MODULE_PARM_DESC(max_user_congthresh,
  50  "Global limit for the maximum congestion threshold an "
  51  "unprivileged user can set");
  52
  53 #define FUSE_SUPER_MAGIC 0x65735546
  54
  55 #define FUSE_DEFAULT_BLKSIZE 512
  56
  57 /** Maximum number of outstanding background requests */
  58 #define FUSE_DEFAULT_MAX_BACKGROUND 12
  59
  60 /** Congestion starts at 75% of maximum */
  61 #define FUSE_DEFAULT_CONGESTION_THRESHOLD (FUSE_DEFAULT_MAX_BACKGROUND * 3 / 4)
  62
  63 #ifdef CONFIG_BLOCK
  64 static struct file_system_type fuseblk_fs_type;
  65 #endif
  66
  67 struct fuse_forget_link *fuse_alloc_forget(void)
  68 {
  69         return kzalloc(sizeof(struct fuse_forget_link), GFP_KERNEL_ACCOUNT);
  70 }
  71
  72 static struct inode *fuse_alloc_inode(struct super_block *sb)
  73 {
  74         struct fuse_inode *fi;
  75
  76         fi = kmem_cache_alloc(fuse_inode_cachep, GFP_KERNEL);
  77         if (!fi)
  78                 return NULL;
  79
  80         fi->i_time = 0;
  81         fi->inval_mask = 0;
  82         fi->nodeid = 0;
  83         fi->nlookup = 0;
  84         fi->attr_version = 0;
  85         fi->orig_ino = 0;
  86         fi->state = 0;
  87         mutex_init(&fi->mutex);
  88         init_rwsem(&fi->i_mmap_sem);
  89         spin_lock_init(&fi->lock);
  90         fi->forget = fuse_alloc_forget();
  91         if (!fi->forget)
  92                 goto out_free;
  93
  94         if (IS_ENABLED(CONFIG_FUSE_DAX) && !fuse_dax_inode_alloc(sb, fi))
  95                 goto out_free_forget;
  96
  97         return &fi->inode;
  98
  99 out_free_forget:
 100         kfree(fi->forget);
 101 out_free:
 102         kmem_cache_free(fuse_inode_cachep, fi);
 103         return NULL;
 104 }
 105
 106 static void fuse_free_inode(struct inode *inode)
 107 {
 108         struct fuse_inode *fi = get_fuse_inode(inode);
 109
 110         mutex_destroy(&fi->mutex);
 111         kfree(fi->forget);
 112 #ifdef CONFIG_FUSE_DAX
 113         kfree(fi->dax);
 114 #endif
 115         kmem_cache_free(fuse_inode_cachep, fi);
 116 }
 117
 118 static void fuse_evict_inode(struct inode *inode)
 119 {
 120         struct fuse_inode *fi = get_fuse_inode(inode);
 121
 122         truncate_inode_pages_final(&inode->i_data);
 123         clear_inode(inode);
 124         if (inode->i_sb->s_flags & SB_ACTIVE) {
 125                 struct fuse_conn *fc = get_fuse_conn(inode);
 126
 127                 if (FUSE_IS_DAX(inode))
 128                         fuse_dax_inode_cleanup(inode);
 129                 if (fi->nlookup) {
 130                         fuse_queue_forget(fc, fi->forget, fi->nodeid,
 131                                           fi->nlookup);
 132                         fi->forget = NULL;
 133                 }
 134         }
 135         if (S_ISREG(inode->i_mode) && !fuse_is_bad(inode)) {
 136                 WARN_ON(!list_empty(&fi->write_files));
 137                 WARN_ON(!list_empty(&fi->queued_writes));
 138         }
 139 }
 140
 141 static int fuse_reconfigure(struct fs_context *fsc)
 142 {
 143         struct super_block *sb = fsc->root->d_sb;
 144
 145         sync_filesystem(sb);
 146         if (fsc->sb_flags & SB_MANDLOCK)
 147                 return -EINVAL;
 148
 149         return 0;
 150 }
 151
 152 /*
 153  * ino_t is 32-bits on 32-bit arch. We have to squash the 64-bit value down
 154  * so that it will fit.
 155  */
 156 static ino_t fuse_squash_ino(u64 ino64)
 157 {
 158         ino_t ino = (ino_t) ino64;
 159         if (sizeof(ino_t) < sizeof(u64))
 160                 ino ^= ino64 >> (sizeof(u64) - sizeof(ino_t)) * 8;
 161         return ino;
 162 }
 163
 164 void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
 165                                    u64 attr_valid)
 166 {
 167         struct fuse_conn *fc = get_fuse_conn(inode);
 168         struct fuse_inode *fi = get_fuse_inode(inode);
 169
 170         lockdep_assert_held(&fi->lock);
 171
 172         fi->attr_version = atomic64_inc_return(&fc->attr_version);
 173         fi->i_time = attr_valid;
 174         WRITE_ONCE(fi->inval_mask, 0);
 175
 176         inode->i_ino     = fuse_squash_ino(attr->ino);
 177         inode->i_mode    = (inode->i_mode & S_IFMT) | (attr->mode & 07777);
 178         set_nlink(inode, attr->nlink);
 179         inode->i_uid     = make_kuid(fc->user_ns, attr->uid);
 180         inode->i_gid     = make_kgid(fc->user_ns, attr->gid);
 181         inode->i_blocks  = attr->blocks;
 182         inode->i_atime.tv_sec   = attr->atime;
 183         inode->i_atime.tv_nsec  = attr->atimensec;
 184         /* mtime from server may be stale due to local buffered write */
 185         if (!fc->writeback_cache || !S_ISREG(inode->i_mode)) {
 186                 inode->i_mtime.tv_sec   = attr->mtime;
 187                 inode->i_mtime.tv_nsec  = attr->mtimensec;
 188                 inode->i_ctime.tv_sec   = attr->ctime;
 189                 inode->i_ctime.tv_nsec  = attr->ctimensec;
 190         }
 191
 192         if (attr->blksize != 0)
 193                 inode->i_blkbits = ilog2(attr->blksize);
 194         else
 195                 inode->i_blkbits = inode->i_sb->s_blocksize_bits;
 196
 197         /*
 198          * Don't set the sticky bit in i_mode, unless we want the VFS
 199          * to check permissions.  This prevents failures due to the
 200          * check in may_delete().
 201          */
 202         fi->orig_i_mode = inode->i_mode;
 203         if (!fc->default_permissions)
 204                 inode->i_mode &= ~S_ISVTX;
 205
 206         fi->orig_ino = attr->ino;
 207
 208         /*
 209          * We are refreshing inode data and it is possible that another
 210          * client set suid/sgid or security.capability xattr. So clear
 211          * S_NOSEC. Ideally, we could have cleared it only if suid/sgid
 212          * was set or if security.capability xattr was set. But we don't
 213          * know if security.capability has been set or not. So clear it
 214          * anyway. Its less efficient but should be safe.
 215          */
 216         inode->i_flags &= ~S_NOSEC;
 217 }
 218
 219 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
 220                             u64 attr_valid, u64 attr_version)
 221 {
 222         struct fuse_conn *fc = get_fuse_conn(inode);
 223         struct fuse_inode *fi = get_fuse_inode(inode);
 224         bool is_wb = fc->writeback_cache;
 225         loff_t oldsize;
 226         struct timespec64 old_mtime;
 227
 228         spin_lock(&fi->lock);
 229         if ((attr_version != 0 && fi->attr_version > attr_version) ||
 230             test_bit(FUSE_I_SIZE_UNSTABLE, &fi->state)) {
 231                 spin_unlock(&fi->lock);
 232                 return;
 233         }
 234
 235         old_mtime = inode->i_mtime;
 236         fuse_change_attributes_common(inode, attr, attr_valid);
 237
 238         oldsize = inode->i_size;
 239         /*
 240          * In case of writeback_cache enabled, the cached writes beyond EOF
 241          * extend local i_size without keeping userspace server in sync. So,
 242          * attr->size coming from server can be stale. We cannot trust it.
 243          */
 244         if (!is_wb || !S_ISREG(inode->i_mode))
 245                 i_size_write(inode, attr->size);
 246         spin_unlock(&fi->lock);
 247
 248         if (!is_wb && S_ISREG(inode->i_mode)) {
 249                 bool inval = false;
 250
 251                 if (oldsize != attr->size) {
 252                         truncate_pagecache(inode, attr->size);
 253                         if (!fc->explicit_inval_data)
 254                                 inval = true;
 255                 } else if (fc->auto_inval_data) {
 256                         struct timespec64 new_mtime = {
 257                                 .tv_sec = attr->mtime,
 258                                 .tv_nsec = attr->mtimensec,
 259                         };
 260
 261                         /*
 262                          * Auto inval mode also checks and invalidates if mtime
 263                          * has changed.
 264                          */
 265                         if (!timespec64_equal(&old_mtime, &new_mtime))
 266                                 inval = true;
 267                 }
 268
 269                 if (inval)
 270                         invalidate_inode_pages2(inode->i_mapping);
 271         }
 272 }
 273
 274 static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
 275 {
 276         inode->i_mode = attr->mode & S_IFMT;
 277         inode->i_size = attr->size;
 278         inode->i_mtime.tv_sec  = attr->mtime;
 279         inode->i_mtime.tv_nsec = attr->mtimensec;
 280         inode->i_ctime.tv_sec  = attr->ctime;
 281         inode->i_ctime.tv_nsec = attr->ctimensec;
 282         if (S_ISREG(inode->i_mode)) {
 283                 fuse_init_common(inode);
 284                 fuse_init_file_inode(inode);
 285         } else if (S_ISDIR(inode->i_mode))
 286                 fuse_init_dir(inode);
 287         else if (S_ISLNK(inode->i_mode))
 288                 fuse_init_symlink(inode);
 289         else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
 290                  S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
 291                 fuse_init_common(inode);
 292                 init_special_inode(inode, inode->i_mode,
 293                                    new_decode_dev(attr->rdev));
 294         } else
 295                 BUG();
 296 }
 297
 298 static int fuse_inode_eq(struct inode *inode, void *_nodeidp)
 299 {
 300         u64 nodeid = *(u64 *) _nodeidp;
 301         if (get_node_id(inode) == nodeid)
 302                 return 1;
 303         else
 304                 return 0;
 305 }
 306
 307 static int fuse_inode_set(struct inode *inode, void *_nodeidp)
 308 {
 309         u64 nodeid = *(u64 *) _nodeidp;
 310         get_fuse_inode(inode)->nodeid = nodeid;
 311         return 0;
 312 }
 313
 314 struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
 315                         int generation, struct fuse_attr *attr,
 316                         u64 attr_valid, u64 attr_version)
 317 {
 318         struct inode *inode;
 319         struct fuse_inode *fi;
 320         struct fuse_conn *fc = get_fuse_conn_super(sb);
 321
 322         /*
 323          * Auto mount points get their node id from the submount root, which is
 324          * not a unique identifier within this filesystem.
 325          *
 326          * To avoid conflicts, do not place submount points into the inode hash
 327          * table.
 328          */
 329         if (fc->auto_submounts && (attr->flags & FUSE_ATTR_SUBMOUNT) &&
 330             S_ISDIR(attr->mode)) {
 331                 inode = new_inode(sb);
 332                 if (!inode)
 333                         return NULL;
 334
 335                 fuse_init_inode(inode, attr);
 336                 get_fuse_inode(inode)->nodeid = nodeid;
 337                 inode->i_flags |= S_AUTOMOUNT;
 338                 goto done;
 339         }
 340
 341 retry:
 342         inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);
 343         if (!inode)
 344                 return NULL;
 345
 346         if ((inode->i_state & I_NEW)) {
 347                 inode->i_flags |= S_NOATIME;
 348                 if (!fc->writeback_cache || !S_ISREG(attr->mode))
 349                         inode->i_flags |= S_NOCMTIME;
 350                 inode->i_generation = generation;
 351                 fuse_init_inode(inode, attr);
 352                 unlock_new_inode(inode);
 353         } else if (fuse_stale_inode(inode, generation, attr)) {
 354                 /* nodeid was reused, any I/O on the old inode should fail */
 355                 fuse_make_bad(inode);
 356                 iput(inode);
 357                 goto retry;
 358         }
 359 done:
 360         fi = get_fuse_inode(inode);
 361         spin_lock(&fi->lock);
 362         fi->nlookup++;
 363         spin_unlock(&fi->lock);
 364         fuse_change_attributes(inode, attr, attr_valid, attr_version);
 365
 366         return inode;
 367 }
 368
 369 struct inode *fuse_ilookup(struct fuse_conn *fc, u64 nodeid,
 370                            struct fuse_mount **fm)
 371 {
 372         struct fuse_mount *fm_iter;
 373         struct inode *inode;
 374
 375         WARN_ON(!rwsem_is_locked(&fc->killsb));
 376         list_for_each_entry(fm_iter, &fc->mounts, fc_entry) {
 377                 if (!fm_iter->sb)
 378                         continue;
 379
 380                 inode = ilookup5(fm_iter->sb, nodeid, fuse_inode_eq, &nodeid);
 381                 if (inode) {
 382                         if (fm)
 383                                 *fm = fm_iter;
 384                         return inode;
 385                 }
 386         }
 387
 388         return NULL;
 389 }
 390
 391 int fuse_reverse_inval_inode(struct fuse_conn *fc, u64 nodeid,
 392                              loff_t offset, loff_t len)
 393 {
 394         struct fuse_inode *fi;
 395         struct inode *inode;
 396         pgoff_t pg_start;
 397         pgoff_t pg_end;
 398
 399         inode = fuse_ilookup(fc, nodeid, NULL);
 400         if (!inode)
 401                 return -ENOENT;
 402
 403         fi = get_fuse_inode(inode);
 404         spin_lock(&fi->lock);
 405         fi->attr_version = atomic64_inc_return(&fc->attr_version);
 406         spin_unlock(&fi->lock);
 407
 408         fuse_invalidate_attr(inode);
 409         forget_all_cached_acls(inode);
 410         if (offset >= 0) {
 411                 pg_start = offset >> PAGE_SHIFT;
 412                 if (len <= 0)
 413                         pg_end = -1;
 414                 else
 415                         pg_end = (offset + len - 1) >> PAGE_SHIFT;
 416                 invalidate_inode_pages2_range(inode->i_mapping,
 417                                               pg_start, pg_end);
 418         }
 419         iput(inode);
 420         return 0;
 421 }
 422
 423 bool fuse_lock_inode(struct inode *inode)
 424 {
 425         bool locked = false;
 426
 427         if (!get_fuse_conn(inode)->parallel_dirops) {
 428                 mutex_lock(&get_fuse_inode(inode)->mutex);
 429                 locked = true;
 430         }
 431
 432         return locked;
 433 }
 434
 435 void fuse_unlock_inode(struct inode *inode, bool locked)
 436 {
 437         if (locked)
 438                 mutex_unlock(&get_fuse_inode(inode)->mutex);
 439 }
 440
 441 static void fuse_umount_begin(struct super_block *sb)
 442 {
 443         struct fuse_conn *fc = get_fuse_conn_super(sb);
 444
 445         if (!fc->no_force_umount)
 446                 fuse_abort_conn(fc);
 447 }
 448
 449 static void fuse_send_destroy(struct fuse_mount *fm)
 450 {
 451         if (fm->fc->conn_init) {
 452                 FUSE_ARGS(args);
 453
 454                 args.opcode = FUSE_DESTROY;
 455                 args.force = true;
 456                 args.nocreds = true;
 457                 fuse_simple_request(fm, &args);
 458         }
 459 }
 460
 461 static void fuse_put_super(struct super_block *sb)
 462 {
 463         struct fuse_mount *fm = get_fuse_mount_super(sb);
 464
 465         fuse_conn_put(fm->fc);
 466         kfree(fm);
 467 }
 468
 469 static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
 470 {
 471         stbuf->f_type    = FUSE_SUPER_MAGIC;
 472         stbuf->f_bsize   = attr->bsize;
 473         stbuf->f_frsize  = attr->frsize;
 474         stbuf->f_blocks  = attr->blocks;
 475         stbuf->f_bfree   = attr->bfree;
 476         stbuf->f_bavail  = attr->bavail;
 477         stbuf->f_files   = attr->files;
 478         stbuf->f_ffree   = attr->ffree;
 479         stbuf->f_namelen = attr->namelen;
 480         /* fsid is left zero */
 481 }
 482
 483 static int fuse_statfs(struct dentry *dentry, struct kstatfs *buf)
 484 {
 485         struct super_block *sb = dentry->d_sb;
 486         struct fuse_mount *fm = get_fuse_mount_super(sb);
 487         FUSE_ARGS(args);
 488         struct fuse_statfs_out outarg;
 489         int err;
 490
 491         if (!fuse_allow_current_process(fm->fc)) {
 492                 buf->f_type = FUSE_SUPER_MAGIC;
 493                 return 0;
 494         }
 495
 496         memset(&outarg, 0, sizeof(outarg));
 497         args.in_numargs = 0;
 498         args.opcode = FUSE_STATFS;
 499         args.nodeid = get_node_id(d_inode(dentry));
 500         args.out_numargs = 1;
 501         args.out_args[0].size = sizeof(outarg);
 502         args.out_args[0].value = &outarg;
 503         err = fuse_simple_request(fm, &args);
 504         if (!err)
 505                 convert_fuse_statfs(buf, &outarg.st);
 506         return err;
 507 }
 508
 509 static int fuse_sync_fs(struct super_block *sb, int wait)
 510 {
 511         struct fuse_mount *fm = get_fuse_mount_super(sb);
 512         struct fuse_conn *fc = fm->fc;
 513         struct fuse_syncfs_in inarg;
 514         FUSE_ARGS(args);
 515         int err;
 516
 517         /*
 518          * Userspace cannot handle the wait == 0 case.  Avoid a
 519          * gratuitous roundtrip.
 520          */
 521         if (!wait)
 522                 return 0;
 523
 524         /* The filesystem is being unmounted.  Nothing to do. */
 525         if (!sb->s_root)
 526                 return 0;
 527
 528         if (!fc->sync_fs)
 529                 return 0;
 530
 531         memset(&inarg, 0, sizeof(inarg));
 532         args.in_numargs = 1;
 533         args.in_args[0].size = sizeof(inarg);
 534         args.in_args[0].value = &inarg;
 535         args.opcode = FUSE_SYNCFS;
 536         args.nodeid = get_node_id(sb->s_root->d_inode);
 537         args.out_numargs = 0;
 538
 539         err = fuse_simple_request(fm, &args);
 540         if (err == -ENOSYS) {
 541                 fc->sync_fs = 0;
 542                 err = 0;
 543         }
 544
 545         return err;
 546 }
 547
 548 enum {
 549         OPT_SOURCE,
 550         OPT_SUBTYPE,
 551         OPT_FD,
 552         OPT_ROOTMODE,
 553         OPT_USER_ID,
 554         OPT_GROUP_ID,
 555         OPT_DEFAULT_PERMISSIONS,
 556         OPT_ALLOW_OTHER,
 557         OPT_MAX_READ,
 558         OPT_BLKSIZE,
 559         OPT_ERR
 560 };
 561
 562 static const struct fs_parameter_spec fuse_fs_parameters[] = {
 563         fsparam_string  ("source",              OPT_SOURCE),
 564         fsparam_u32     ("fd",                  OPT_FD),
 565         fsparam_u32oct  ("rootmode",            OPT_ROOTMODE),
 566         fsparam_u32     ("user_id",             OPT_USER_ID),
 567         fsparam_u32     ("group_id",            OPT_GROUP_ID),
 568         fsparam_flag    ("default_permissions", OPT_DEFAULT_PERMISSIONS),
 569         fsparam_flag    ("allow_other",         OPT_ALLOW_OTHER),
 570         fsparam_u32     ("max_read",            OPT_MAX_READ),
 571         fsparam_u32     ("blksize",             OPT_BLKSIZE),
 572         fsparam_string  ("subtype",             OPT_SUBTYPE),
 573         {}
 574 };
 575
 576 static int fuse_parse_param(struct fs_context *fsc, struct fs_parameter *param)
 577 {
 578         struct fs_parse_result result;
 579         struct fuse_fs_context *ctx = fsc->fs_private;
 580         int opt;
 581
 582         if (fsc->purpose == FS_CONTEXT_FOR_RECONFIGURE) {
 583                 /*
 584                  * Ignore options coming from mount(MS_REMOUNT) for backward
 585                  * compatibility.
 586                  */
 587                 if (fsc->oldapi)
 588                         return 0;
 589
 590                 return invalfc(fsc, "No changes allowed in reconfigure");
 591         }
 592
 593         opt = fs_parse(fsc, fuse_fs_parameters, param, &result);
 594         if (opt < 0)
 595                 return opt;
 596
 597         switch (opt) {
 598         case OPT_SOURCE:
 599                 if (fsc->source)
 600                         return invalfc(fsc, "Multiple sources specified");
 601                 fsc->source = param->string;
 602                 param->string = NULL;
 603                 break;
 604
 605         case OPT_SUBTYPE:
 606                 if (ctx->subtype)
 607                         return invalfc(fsc, "Multiple subtypes specified");
 608                 ctx->subtype = param->string;
 609                 param->string = NULL;
 610                 return 0;
 611
 612         case OPT_FD:
 613                 ctx->fd = result.uint_32;
 614                 ctx->fd_present = true;
 615                 break;
 616
 617         case OPT_ROOTMODE:
 618                 if (!fuse_valid_type(result.uint_32))
 619                         return invalfc(fsc, "Invalid rootmode");
 620                 ctx->rootmode = result.uint_32;
 621                 ctx->rootmode_present = true;
 622                 break;
 623
 624         case OPT_USER_ID:
 625                 ctx->user_id = make_kuid(fsc->user_ns, result.uint_32);
 626                 if (!uid_valid(ctx->user_id))
 627                         return invalfc(fsc, "Invalid user_id");
 628                 ctx->user_id_present = true;
 629                 break;
 630
 631         case OPT_GROUP_ID:
 632                 ctx->group_id = make_kgid(fsc->user_ns, result.uint_32);
 633                 if (!gid_valid(ctx->group_id))
 634                         return invalfc(fsc, "Invalid group_id");
 635                 ctx->group_id_present = true;
 636                 break;
 637
 638         case OPT_DEFAULT_PERMISSIONS:
 639                 ctx->default_permissions = true;
 640                 break;
 641
 642         case OPT_ALLOW_OTHER:
 643                 ctx->allow_other = true;
 644                 break;
 645
 646         case OPT_MAX_READ:
 647                 ctx->max_read = result.uint_32;
 648                 break;
 649
 650         case OPT_BLKSIZE:
 651                 if (!ctx->is_bdev)
 652                         return invalfc(fsc, "blksize only supported for fuseblk");
 653                 ctx->blksize = result.uint_32;
 654                 break;
 655
 656         default:
 657                 return -EINVAL;
 658         }
 659
 660         return 0;
 661 }
 662
 663 static void fuse_free_fsc(struct fs_context *fsc)
 664 {
 665         struct fuse_fs_context *ctx = fsc->fs_private;
 666
 667         if (ctx) {
 668                 kfree(ctx->subtype);
 669                 kfree(ctx);
 670         }
 671 }
 672
 673 static int fuse_show_options(struct seq_file *m, struct dentry *root)
 674 {
 675         struct super_block *sb = root->d_sb;
 676         struct fuse_conn *fc = get_fuse_conn_super(sb);
 677
 678         if (fc->legacy_opts_show) {
 679                 seq_printf(m, ",user_id=%u",
 680                            from_kuid_munged(fc->user_ns, fc->user_id));
 681                 seq_printf(m, ",group_id=%u",
 682                            from_kgid_munged(fc->user_ns, fc->group_id));
 683                 if (fc->default_permissions)
 684                         seq_puts(m, ",default_permissions");
 685                 if (fc->allow_other)
 686                         seq_puts(m, ",allow_other");
 687                 if (fc->max_read != ~0)
 688                         seq_printf(m, ",max_read=%u", fc->max_read);
 689                 if (sb->s_bdev && sb->s_blocksize != FUSE_DEFAULT_BLKSIZE)
 690                         seq_printf(m, ",blksize=%lu", sb->s_blocksize);
 691         }
 692 #ifdef CONFIG_FUSE_DAX
 693         if (fc->dax)
 694                 seq_puts(m, ",dax");
 695 #endif
 696
 697         return 0;
 698 }
 699
 700 static void fuse_iqueue_init(struct fuse_iqueue *fiq,
 701                              const struct fuse_iqueue_ops *ops,
 702                              void *priv)
 703 {
 704         memset(fiq, 0, sizeof(struct fuse_iqueue));
 705         spin_lock_init(&fiq->lock);
 706         init_waitqueue_head(&fiq->waitq);
 707         INIT_LIST_HEAD(&fiq->pending);
 708         INIT_LIST_HEAD(&fiq->interrupts);
 709         fiq->forget_list_tail = &fiq->forget_list_head;
 710         fiq->connected = 1;
 711         fiq->ops = ops;
 712         fiq->priv = priv;
 713 }
 714
 715 static void fuse_pqueue_init(struct fuse_pqueue *fpq)
 716 {
 717         unsigned int i;
 718
 719         spin_lock_init(&fpq->lock);
 720         for (i = 0; i < FUSE_PQ_HASH_SIZE; i++)
 721                 INIT_LIST_HEAD(&fpq->processing[i]);
 722         INIT_LIST_HEAD(&fpq->io);
 723         fpq->connected = 1;
 724 }
 725
 726 void fuse_conn_init(struct fuse_conn *fc, struct fuse_mount *fm,
 727                     struct user_namespace *user_ns,
 728                     const struct fuse_iqueue_ops *fiq_ops, void *fiq_priv)
 729 {
 730         memset(fc, 0, sizeof(*fc));
 731         spin_lock_init(&fc->lock);
 732         spin_lock_init(&fc->bg_lock);
 733         init_rwsem(&fc->killsb);
 734         refcount_set(&fc->count, 1);
 735         atomic_set(&fc->dev_count, 1);
 736         init_waitqueue_head(&fc->blocked_waitq);
 737         fuse_iqueue_init(&fc->iq, fiq_ops, fiq_priv);
 738         INIT_LIST_HEAD(&fc->bg_queue);
 739         INIT_LIST_HEAD(&fc->entry);
 740         INIT_LIST_HEAD(&fc->devices);
 741         atomic_set(&fc->num_waiting, 0);
 742         fc->max_background = FUSE_DEFAULT_MAX_BACKGROUND;
 743         fc->congestion_threshold = FUSE_DEFAULT_CONGESTION_THRESHOLD;
 744         atomic64_set(&fc->khctr, 0);
 745         fc->polled_files = RB_ROOT;
 746         fc->blocked = 0;
 747         fc->initialized = 0;
 748         fc->connected = 1;
 749         atomic64_set(&fc->attr_version, 1);
 750         get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));
 751         fc->pid_ns = get_pid_ns(task_active_pid_ns(current));
 752         fc->user_ns = get_user_ns(user_ns);
 753         fc->max_pages = FUSE_DEFAULT_MAX_PAGES_PER_REQ;
 754         fc->max_pages_limit = FUSE_MAX_MAX_PAGES;
 755
 756         INIT_LIST_HEAD(&fc->mounts);
 757         list_add(&fm->fc_entry, &fc->mounts);
 758         fm->fc = fc;
 759 }
 760 EXPORT_SYMBOL_GPL(fuse_conn_init);
 761
 762 void fuse_conn_put(struct fuse_conn *fc)
 763 {
 764         if (refcount_dec_and_test(&fc->count)) {
 765                 struct fuse_iqueue *fiq = &fc->iq;
 766
 767                 if (IS_ENABLED(CONFIG_FUSE_DAX))
 768                         fuse_dax_conn_free(fc);
 769                 if (fiq->ops->release)
 770                         fiq->ops->release(fiq);
 771                 put_pid_ns(fc->pid_ns);
 772                 put_user_ns(fc->user_ns);
 773                 fc->release(fc);
 774         }
 775 }
 776 EXPORT_SYMBOL_GPL(fuse_conn_put);
 777
 778 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc)
 779 {
 780         refcount_inc(&fc->count);
 781         return fc;
 782 }
 783 EXPORT_SYMBOL_GPL(fuse_conn_get);
 784
 785 static struct inode *fuse_get_root_inode(struct super_block *sb, unsigned mode)
 786 {
 787         struct fuse_attr attr;
 788         memset(&attr, 0, sizeof(attr));
 789
 790         attr.mode = mode;
 791         attr.ino = FUSE_ROOT_ID;
 792         attr.nlink = 1;
 793         return fuse_iget(sb, 1, 0, &attr, 0, 0);
 794 }
 795
 796 struct fuse_inode_handle {
 797         u64 nodeid;
 798         u32 generation;
 799 };
 800
 801 static struct dentry *fuse_get_dentry(struct super_block *sb,
 802                                       struct fuse_inode_handle *handle)
 803 {
 804         struct fuse_conn *fc = get_fuse_conn_super(sb);
 805         struct inode *inode;
 806         struct dentry *entry;
 807         int err = -ESTALE;
 808
 809         if (handle->nodeid == 0)
 810                 goto out_err;
 811
 812         inode = ilookup5(sb, handle->nodeid, fuse_inode_eq, &handle->nodeid);
 813         if (!inode) {
 814                 struct fuse_entry_out outarg;
 815                 const struct qstr name = QSTR_INIT(".", 1);
 816
 817                 if (!fc->export_support)
 818                         goto out_err;
 819
 820                 err = fuse_lookup_name(sb, handle->nodeid, &name, &outarg,
 821                                        &inode);
 822                 if (err && err != -ENOENT)
 823                         goto out_err;
 824                 if (err || !inode) {
 825                         err = -ESTALE;
 826                         goto out_err;
 827                 }
 828                 err = -EIO;
 829                 if (get_node_id(inode) != handle->nodeid)
 830                         goto out_iput;
 831         }
 832         err = -ESTALE;
 833         if (inode->i_generation != handle->generation)
 834                 goto out_iput;
 835
 836         entry = d_obtain_alias(inode);
 837         if (!IS_ERR(entry) && get_node_id(inode) != FUSE_ROOT_ID)
 838                 fuse_invalidate_entry_cache(entry);
 839
 840         return entry;
 841
 842  out_iput:
 843         iput(inode);
 844  out_err:
 845         return ERR_PTR(err);
 846 }
 847
 848 static int fuse_encode_fh(struct inode *inode, u32 *fh, int *max_len,
 849                            struct inode *parent)
 850 {
 851         int len = parent ? 6 : 3;
 852         u64 nodeid;
 853         u32 generation;
 854
 855         if (*max_len < len) {
 856                 *max_len = len;
 857                 return  FILEID_INVALID;
 858         }
 859
 860         nodeid = get_fuse_inode(inode)->nodeid;
 861         generation = inode->i_generation;
 862
 863         fh[0] = (u32)(nodeid >> 32);
 864         fh[1] = (u32)(nodeid & 0xffffffff);
 865         fh[2] = generation;
 866
 867         if (parent) {
 868                 nodeid = get_fuse_inode(parent)->nodeid;
 869                 generation = parent->i_generation;
 870
 871                 fh[3] = (u32)(nodeid >> 32);
 872                 fh[4] = (u32)(nodeid & 0xffffffff);
 873                 fh[5] = generation;
 874         }
 875
 876         *max_len = len;
 877         return parent ? 0x82 : 0x81;
 878 }
 879
 880 static struct dentry *fuse_fh_to_dentry(struct super_block *sb,
 881                 struct fid *fid, int fh_len, int fh_type)
 882 {
 883         struct fuse_inode_handle handle;
 884
 885         if ((fh_type != 0x81 && fh_type != 0x82) || fh_len < 3)
 886                 return NULL;
 887
 888         handle.nodeid = (u64) fid->raw[0] << 32;
 889         handle.nodeid |= (u64) fid->raw[1];
 890         handle.generation = fid->raw[2];
 891         return fuse_get_dentry(sb, &handle);
 892 }
 893
 894 static struct dentry *fuse_fh_to_parent(struct super_block *sb,
 895                 struct fid *fid, int fh_len, int fh_type)
 896 {
 897         struct fuse_inode_handle parent;
 898
 899         if (fh_type != 0x82 || fh_len < 6)
 900                 return NULL;
 901
 902         parent.nodeid = (u64) fid->raw[3] << 32;
 903         parent.nodeid |= (u64) fid->raw[4];
 904         parent.generation = fid->raw[5];
 905         return fuse_get_dentry(sb, &parent);
 906 }
 907
 908 static struct dentry *fuse_get_parent(struct dentry *child)
 909 {
 910         struct inode *child_inode = d_inode(child);
 911         struct fuse_conn *fc = get_fuse_conn(child_inode);
 912         struct inode *inode;
 913         struct dentry *parent;
 914         struct fuse_entry_out outarg;
 915         int err;
 916
 917         if (!fc->export_support)
 918                 return ERR_PTR(-ESTALE);
 919
 920         err = fuse_lookup_name(child_inode->i_sb, get_node_id(child_inode),
 921                                &dotdot_name, &outarg, &inode);
 922         if (err) {
 923                 if (err == -ENOENT)
 924                         return ERR_PTR(-ESTALE);
 925                 return ERR_PTR(err);
 926         }
 927
 928         parent = d_obtain_alias(inode);
 929         if (!IS_ERR(parent) && get_node_id(inode) != FUSE_ROOT_ID)
 930                 fuse_invalidate_entry_cache(parent);
 931
 932         return parent;
 933 }
 934
 935 static const struct export_operations fuse_export_operations = {
 936         .fh_to_dentry   = fuse_fh_to_dentry,
 937         .fh_to_parent   = fuse_fh_to_parent,
 938         .encode_fh      = fuse_encode_fh,
 939         .get_parent     = fuse_get_parent,
 940 };
 941
 942 static const struct super_operations fuse_super_operations = {
 943         .alloc_inode    = fuse_alloc_inode,
 944         .free_inode     = fuse_free_inode,
 945         .evict_inode    = fuse_evict_inode,
 946         .write_inode    = fuse_write_inode,
 947         .drop_inode     = generic_delete_inode,
 948         .put_super      = fuse_put_super,
 949         .umount_begin   = fuse_umount_begin,
 950         .statfs         = fuse_statfs,
 951         .sync_fs        = fuse_sync_fs,
 952         .show_options   = fuse_show_options,
 953 };
 954
 955 static void sanitize_global_limit(unsigned *limit)
 956 {
 957         /*
 958          * The default maximum number of async requests is calculated to consume
 959          * 1/2^13 of the total memory, assuming 392 bytes per request.
 960          */
 961         if (*limit == 0)
 962                 *limit = ((totalram_pages() << PAGE_SHIFT) >> 13) / 392;
 963
 964         if (*limit >= 1 << 16)
 965                 *limit = (1 << 16) - 1;
 966 }
 967
 968 static int set_global_limit(const char *val, const struct kernel_param *kp)
 969 {
 970         int rv;
 971
 972         rv = param_set_uint(val, kp);
 973         if (rv)
 974                 return rv;
 975
 976         sanitize_global_limit((unsigned *)kp->arg);
 977
 978         return 0;
 979 }
 980
 981 static void process_init_limits(struct fuse_conn *fc, struct fuse_init_out *arg)
 982 {
 983         int cap_sys_admin = capable(CAP_SYS_ADMIN);
 984
 985         if (arg->minor < 13)
 986                 return;
 987
 988         sanitize_global_limit(&max_user_bgreq);
 989         sanitize_global_limit(&max_user_congthresh);
 990
 991         spin_lock(&fc->bg_lock);
 992         if (arg->max_background) {
 993                 fc->max_background = arg->max_background;
 994
 995                 if (!cap_sys_admin && fc->max_background > max_user_bgreq)
 996                         fc->max_background = max_user_bgreq;
 997         }
 998         if (arg->congestion_threshold) {
 999                 fc->congestion_threshold = arg->congestion_threshold;
1000
1001                 if (!cap_sys_admin &&
1002                     fc->congestion_threshold > max_user_congthresh)
1003                         fc->congestion_threshold = max_user_congthresh;
1004         }
1005         spin_unlock(&fc->bg_lock);
1006 }
1007
1008 struct fuse_init_args {
1009         struct fuse_args args;
1010         struct fuse_init_in in;
1011         struct fuse_init_out out;
1012 };
1013
1014 static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
1015                                int error)
1016 {
1017         struct fuse_conn *fc = fm->fc;
1018         struct fuse_init_args *ia = container_of(args, typeof(*ia), args);
1019         struct fuse_init_out *arg = &ia->out;
1020         bool ok = true;
1021
1022         if (error || arg->major != FUSE_KERNEL_VERSION)
1023                 ok = false;
1024         else {
1025                 unsigned long ra_pages;
1026
1027                 process_init_limits(fc, arg);
1028
1029                 if (arg->minor >= 6) {
1030                         ra_pages = arg->max_readahead / PAGE_SIZE;
1031                         if (arg->flags & FUSE_ASYNC_READ)
1032                                 fc->async_read = 1;
1033                         if (!(arg->flags & FUSE_POSIX_LOCKS))
1034                                 fc->no_lock = 1;
1035                         if (arg->minor >= 17) {
1036                                 if (!(arg->flags & FUSE_FLOCK_LOCKS))
1037                                         fc->no_flock = 1;
1038                         } else {
1039                                 if (!(arg->flags & FUSE_POSIX_LOCKS))
1040                                         fc->no_flock = 1;
1041                         }
1042                         if (arg->flags & FUSE_ATOMIC_O_TRUNC)
1043                                 fc->atomic_o_trunc = 1;
1044                         if (arg->minor >= 9) {
1045                                 /* LOOKUP has dependency on proto version */
1046                                 if (arg->flags & FUSE_EXPORT_SUPPORT)
1047                                         fc->export_support = 1;
1048                         }
1049                         if (arg->flags & FUSE_BIG_WRITES)
1050                                 fc->big_writes = 1;
1051                         if (arg->flags & FUSE_DONT_MASK)
1052                                 fc->dont_mask = 1;
1053                         if (arg->flags & FUSE_AUTO_INVAL_DATA)
1054                                 fc->auto_inval_data = 1;
1055                         else if (arg->flags & FUSE_EXPLICIT_INVAL_DATA)
1056                                 fc->explicit_inval_data = 1;
1057                         if (arg->flags & FUSE_DO_READDIRPLUS) {
1058                                 fc->do_readdirplus = 1;
1059                                 if (arg->flags & FUSE_READDIRPLUS_AUTO)
1060                                         fc->readdirplus_auto = 1;
1061                         }
1062                         if (arg->flags & FUSE_ASYNC_DIO)
1063                                 fc->async_dio = 1;
1064                         if (arg->flags & FUSE_WRITEBACK_CACHE)
1065                                 fc->writeback_cache = 1;
1066                         if (arg->flags & FUSE_PARALLEL_DIROPS)
1067                                 fc->parallel_dirops = 1;
1068                         if (arg->flags & FUSE_HANDLE_KILLPRIV)
1069                                 fc->handle_killpriv = 1;
1070                         if (arg->time_gran && arg->time_gran <= 1000000000)
1071                                 fm->sb->s_time_gran = arg->time_gran;
1072                         if ((arg->flags & FUSE_POSIX_ACL)) {
1073                                 fc->default_permissions = 1;
1074                                 fc->posix_acl = 1;
1075                                 fm->sb->s_xattr = fuse_acl_xattr_handlers;
1076                         }
1077                         if (arg->flags & FUSE_CACHE_SYMLINKS)
1078                                 fc->cache_symlinks = 1;
1079                         if (arg->flags & FUSE_ABORT_ERROR)
1080                                 fc->abort_err = 1;
1081                         if (arg->flags & FUSE_MAX_PAGES) {
1082                                 fc->max_pages =
1083                                         min_t(unsigned int, fc->max_pages_limit,
1084                                         max_t(unsigned int, arg->max_pages, 1));
1085                         }
1086                         if (IS_ENABLED(CONFIG_FUSE_DAX) &&
1087                             arg->flags & FUSE_MAP_ALIGNMENT &&
1088                             !fuse_dax_check_alignment(fc, arg->map_alignment)) {
1089                                 ok = false;
1090                         }
1091                         if (arg->flags & FUSE_HANDLE_KILLPRIV_V2) {
1092                                 fc->handle_killpriv_v2 = 1;
1093                                 fm->sb->s_flags |= SB_NOSEC;
1094                         }
1095                         if (arg->flags & FUSE_SETXATTR_EXT)
1096                                 fc->setxattr_ext = 1;
1097                 } else {
1098                         ra_pages = fc->max_read / PAGE_SIZE;
1099                         fc->no_lock = 1;
1100                         fc->no_flock = 1;
1101                 }
1102
1103                 fm->sb->s_bdi->ra_pages =
1104                                 min(fm->sb->s_bdi->ra_pages, ra_pages);
1105                 fc->minor = arg->minor;
1106                 fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
1107                 fc->max_write = max_t(unsigned, 4096, fc->max_write);
1108                 fc->conn_init = 1;
1109         }
1110         kfree(ia);
1111
1112         if (!ok) {
1113                 fc->conn_init = 0;
1114                 fc->conn_error = 1;
1115         }
1116
1117         fuse_set_initialized(fc);
1118         wake_up_all(&fc->blocked_waitq);
1119 }
1120
1121 void fuse_send_init(struct fuse_mount *fm)
1122 {
1123         struct fuse_init_args *ia;
1124
1125         ia = kzalloc(sizeof(*ia), GFP_KERNEL | __GFP_NOFAIL);
1126
1127         ia->in.major = FUSE_KERNEL_VERSION;
1128         ia->in.minor = FUSE_KERNEL_MINOR_VERSION;
1129         ia->in.max_readahead = fm->sb->s_bdi->ra_pages * PAGE_SIZE;
1130         ia->in.flags |=
1131                 FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |
1132                 FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES | FUSE_DONT_MASK |
1133                 FUSE_SPLICE_WRITE | FUSE_SPLICE_MOVE | FUSE_SPLICE_READ |
1134                 FUSE_FLOCK_LOCKS | FUSE_HAS_IOCTL_DIR | FUSE_AUTO_INVAL_DATA |
1135                 FUSE_DO_READDIRPLUS | FUSE_READDIRPLUS_AUTO | FUSE_ASYNC_DIO |
1136                 FUSE_WRITEBACK_CACHE | FUSE_NO_OPEN_SUPPORT |
1137                 FUSE_PARALLEL_DIROPS | FUSE_HANDLE_KILLPRIV | FUSE_POSIX_ACL |
1138                 FUSE_ABORT_ERROR | FUSE_MAX_PAGES | FUSE_CACHE_SYMLINKS |
1139                 FUSE_NO_OPENDIR_SUPPORT | FUSE_EXPLICIT_INVAL_DATA |
1140                 FUSE_HANDLE_KILLPRIV_V2 | FUSE_SETXATTR_EXT;
1141 #ifdef CONFIG_FUSE_DAX
1142         if (fm->fc->dax)
1143                 ia->in.flags |= FUSE_MAP_ALIGNMENT;
1144 #endif
1145         if (fm->fc->auto_submounts)
1146                 ia->in.flags |= FUSE_SUBMOUNTS;
1147
1148         ia->args.opcode = FUSE_INIT;
1149         ia->args.in_numargs = 1;
1150         ia->args.in_args[0].size = sizeof(ia->in);
1151         ia->args.in_args[0].value = &ia->in;
1152         ia->args.out_numargs = 1;
1153         /* Variable length argument used for backward compatibility
1154            with interface version < 7.5.  Rest of init_out is zeroed
1155            by do_get_request(), so a short reply is not a problem */
1156         ia->args.out_argvar = true;
1157         ia->args.out_args[0].size = sizeof(ia->out);
1158         ia->args.out_args[0].value = &ia->out;
1159         ia->args.force = true;
1160         ia->args.nocreds = true;
1161         ia->args.end = process_init_reply;
1162
1163         if (fuse_simple_background(fm, &ia->args, GFP_KERNEL) != 0)
1164                 process_init_reply(fm, &ia->args, -ENOTCONN);
1165 }
1166 EXPORT_SYMBOL_GPL(fuse_send_init);
1167
1168 void fuse_free_conn(struct fuse_conn *fc)
1169 {
1170         WARN_ON(!list_empty(&fc->devices));
1171         kfree_rcu(fc, rcu);
1172 }
1173 EXPORT_SYMBOL_GPL(fuse_free_conn);
1174
1175 static int fuse_bdi_init(struct fuse_conn *fc, struct super_block *sb)
1176 {
1177         int err;
1178         char *suffix = "";
1179
1180         if (sb->s_bdev) {
1181                 suffix = "-fuseblk";
1182                 /*
1183                  * sb->s_bdi points to blkdev's bdi however we want to redirect
1184                  * it to our private bdi...
1185                  */
1186                 bdi_put(sb->s_bdi);
1187                 sb->s_bdi = &noop_backing_dev_info;
1188         }
1189         err = super_setup_bdi_name(sb, "%u:%u%s", MAJOR(fc->dev),
1190                                    MINOR(fc->dev), suffix);
1191         if (err)
1192                 return err;
1193
1194         /* fuse does it's own writeback accounting */
1195         sb->s_bdi->capabilities &= ~BDI_CAP_WRITEBACK_ACCT;
1196         sb->s_bdi->capabilities |= BDI_CAP_STRICTLIMIT;
1197
1198         /*
1199          * For a single fuse filesystem use max 1% of dirty +
1200          * writeback threshold.
1201          *
1202          * This gives about 1M of write buffer for memory maps on a
1203          * machine with 1G and 10% dirty_ratio, which should be more
1204          * than enough.
1205          *
1206          * Privileged users can raise it by writing to
1207          *
1208          *    /sys/class/bdi/<bdi>/max_ratio
1209          */
1210         bdi_set_max_ratio(sb->s_bdi, 1);
1211
1212         return 0;
1213 }
1214
1215 struct fuse_dev *fuse_dev_alloc(void)
1216 {
1217         struct fuse_dev *fud;
1218         struct list_head *pq;
1219
1220         fud = kzalloc(sizeof(struct fuse_dev), GFP_KERNEL);
1221         if (!fud)
1222                 return NULL;
1223
1224         pq = kcalloc(FUSE_PQ_HASH_SIZE, sizeof(struct list_head), GFP_KERNEL);
1225         if (!pq) {
1226                 kfree(fud);
1227                 return NULL;
1228         }
1229
1230         fud->pq.processing = pq;
1231         fuse_pqueue_init(&fud->pq);
1232
1233         return fud;
1234 }
1235 EXPORT_SYMBOL_GPL(fuse_dev_alloc);
1236
1237 void fuse_dev_install(struct fuse_dev *fud, struct fuse_conn *fc)
1238 {
1239         fud->fc = fuse_conn_get(fc);
1240         spin_lock(&fc->lock);
1241         list_add_tail(&fud->entry, &fc->devices);
1242         spin_unlock(&fc->lock);
1243 }
1244 EXPORT_SYMBOL_GPL(fuse_dev_install);
1245
1246 struct fuse_dev *fuse_dev_alloc_install(struct fuse_conn *fc)
1247 {
1248         struct fuse_dev *fud;
1249
1250         fud = fuse_dev_alloc();
1251         if (!fud)
1252                 return NULL;
1253
1254         fuse_dev_install(fud, fc);
1255         return fud;
1256 }
1257 EXPORT_SYMBOL_GPL(fuse_dev_alloc_install);
1258
1259 void fuse_dev_free(struct fuse_dev *fud)
1260 {
1261         struct fuse_conn *fc = fud->fc;
1262
1263         if (fc) {
1264                 spin_lock(&fc->lock);
1265                 list_del(&fud->entry);
1266                 spin_unlock(&fc->lock);
1267
1268                 fuse_conn_put(fc);
1269         }
1270         kfree(fud->pq.processing);
1271         kfree(fud);
1272 }
1273 EXPORT_SYMBOL_GPL(fuse_dev_free);
1274
1275 static void fuse_fill_attr_from_inode(struct fuse_attr *attr,
1276                                       const struct fuse_inode *fi)
1277 {
1278         *attr = (struct fuse_attr){
1279                 .ino            = fi->inode.i_ino,
1280                 .size           = fi->inode.i_size,
1281                 .blocks         = fi->inode.i_blocks,
1282                 .atime          = fi->inode.i_atime.tv_sec,
1283                 .mtime          = fi->inode.i_mtime.tv_sec,
1284                 .ctime          = fi->inode.i_ctime.tv_sec,
1285                 .atimensec      = fi->inode.i_atime.tv_nsec,
1286                 .mtimensec      = fi->inode.i_mtime.tv_nsec,
1287                 .ctimensec      = fi->inode.i_ctime.tv_nsec,
1288                 .mode           = fi->inode.i_mode,
1289                 .nlink          = fi->inode.i_nlink,
1290                 .uid            = fi->inode.i_uid.val,
1291                 .gid            = fi->inode.i_gid.val,
1292                 .rdev           = fi->inode.i_rdev,
1293                 .blksize        = 1u << fi->inode.i_blkbits,
1294         };
1295 }
1296
1297 static void fuse_sb_defaults(struct super_block *sb)
1298 {
1299         sb->s_magic = FUSE_SUPER_MAGIC;
1300         sb->s_op = &fuse_super_operations;
1301         sb->s_xattr = fuse_xattr_handlers;
1302         sb->s_maxbytes = MAX_LFS_FILESIZE;
1303         sb->s_time_gran = 1;
1304         sb->s_export_op = &fuse_export_operations;
1305         sb->s_iflags |= SB_I_IMA_UNVERIFIABLE_SIGNATURE;
1306         if (sb->s_user_ns != &init_user_ns)
1307                 sb->s_iflags |= SB_I_UNTRUSTED_MOUNTER;
1308         sb->s_flags &= ~(SB_NOSEC | SB_I_VERSION);
1309
1310         /*
1311          * If we are not in the initial user namespace posix
1312          * acls must be translated.
1313          */
1314         if (sb->s_user_ns != &init_user_ns)
1315                 sb->s_xattr = fuse_no_acl_xattr_handlers;
1316 }
1317
1318 static int fuse_fill_super_submount(struct super_block *sb,
1319                                     struct fuse_inode *parent_fi)
1320 {
1321         struct fuse_mount *fm = get_fuse_mount_super(sb);
1322         struct super_block *parent_sb = parent_fi->inode.i_sb;
1323         struct fuse_attr root_attr;
1324         struct inode *root;
1325
1326         fuse_sb_defaults(sb);
1327         fm->sb = sb;
1328
1329         WARN_ON(sb->s_bdi != &noop_backing_dev_info);
1330         sb->s_bdi = bdi_get(parent_sb->s_bdi);
1331
1332         sb->s_xattr = parent_sb->s_xattr;
1333         sb->s_time_gran = parent_sb->s_time_gran;
1334         sb->s_blocksize = parent_sb->s_blocksize;
1335         sb->s_blocksize_bits = parent_sb->s_blocksize_bits;
1336         sb->s_subtype = kstrdup(parent_sb->s_subtype, GFP_KERNEL);
1337         if (parent_sb->s_subtype && !sb->s_subtype)
1338                 return -ENOMEM;
1339
1340         fuse_fill_attr_from_inode(&root_attr, parent_fi);
1341         root = fuse_iget(sb, parent_fi->nodeid, 0, &root_attr, 0, 0);
1342         /*
1343          * This inode is just a duplicate, so it is not looked up and
1344          * its nlookup should not be incremented.  fuse_iget() does
1345          * that, though, so undo it here.
1346          */
1347         get_fuse_inode(root)->nlookup--;
1348         sb->s_d_op = &fuse_dentry_operations;
1349         sb->s_root = d_make_root(root);
1350         if (!sb->s_root)
1351                 return -ENOMEM;
1352
1353         return 0;
1354 }
1355
1356 /* Filesystem context private data holds the FUSE inode of the mount point */
1357 static int fuse_get_tree_submount(struct fs_context *fsc)
1358 {
1359         struct fuse_mount *fm;
1360         struct fuse_inode *mp_fi = fsc->fs_private;
1361         struct fuse_conn *fc = get_fuse_conn(&mp_fi->inode);
1362         struct super_block *sb;
1363         int err;
1364
1365         fm = kzalloc(sizeof(struct fuse_mount), GFP_KERNEL);
1366         if (!fm)
1367                 return -ENOMEM;
1368
1369         fsc->s_fs_info = fm;
1370         sb = sget_fc(fsc, NULL, set_anon_super_fc);
1371         if (IS_ERR(sb)) {
1372                 kfree(fm);
1373                 return PTR_ERR(sb);
1374         }
1375         fm->fc = fuse_conn_get(fc);
1376
1377         /* Initialize superblock, making @mp_fi its root */
1378         err = fuse_fill_super_submount(sb, mp_fi);
1379         if (err) {
1380                 fuse_conn_put(fc);
1381                 kfree(fm);
1382                 sb->s_fs_info = NULL;
1383                 deactivate_locked_super(sb);
1384                 return err;
1385         }
1386
1387         down_write(&fc->killsb);
1388         list_add_tail(&fm->fc_entry, &fc->mounts);
1389         up_write(&fc->killsb);
1390
1391         sb->s_flags |= SB_ACTIVE;
1392         fsc->root = dget(sb->s_root);
1393
1394         return 0;
1395 }
1396
1397 static const struct fs_context_operations fuse_context_submount_ops = {
1398         .get_tree       = fuse_get_tree_submount,
1399 };
1400
1401 int fuse_init_fs_context_submount(struct fs_context *fsc)
1402 {
1403         fsc->ops = &fuse_context_submount_ops;
1404         return 0;
1405 }
1406 EXPORT_SYMBOL_GPL(fuse_init_fs_context_submount);
1407
1408 int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
1409 {
1410         struct fuse_dev *fud = NULL;
1411         struct fuse_mount *fm = get_fuse_mount_super(sb);
1412         struct fuse_conn *fc = fm->fc;
1413         struct inode *root;
1414         struct dentry *root_dentry;
1415         int err;
1416
1417         err = -EINVAL;
1418         if (sb->s_flags & SB_MANDLOCK)
1419                 goto err;
1420
1421         fuse_sb_defaults(sb);
1422
1423         if (ctx->is_bdev) {
1424 #ifdef CONFIG_BLOCK
1425                 err = -EINVAL;
1426                 if (!sb_set_blocksize(sb, ctx->blksize))
1427                         goto err;
1428 #endif
1429         } else {
1430                 sb->s_blocksize = PAGE_SIZE;
1431                 sb->s_blocksize_bits = PAGE_SHIFT;
1432         }
1433
1434         sb->s_subtype = ctx->subtype;
1435         ctx->subtype = NULL;
1436         if (IS_ENABLED(CONFIG_FUSE_DAX)) {
1437                 err = fuse_dax_conn_alloc(fc, ctx->dax_dev);
1438                 if (err)
1439                         goto err;
1440         }
1441
1442         if (ctx->fudptr) {
1443                 err = -ENOMEM;
1444                 fud = fuse_dev_alloc_install(fc);
1445                 if (!fud)
1446                         goto err_free_dax;
1447         }
1448
1449         fc->dev = sb->s_dev;
1450         fm->sb = sb;
1451         err = fuse_bdi_init(fc, sb);
1452         if (err)
1453                 goto err_dev_free;
1454
1455         /* Handle umasking inside the fuse code */
1456         if (sb->s_flags & SB_POSIXACL)
1457                 fc->dont_mask = 1;
1458         sb->s_flags |= SB_POSIXACL;
1459
1460         fc->default_permissions = ctx->default_permissions;
1461         fc->allow_other = ctx->allow_other;
1462         fc->user_id = ctx->user_id;
1463         fc->group_id = ctx->group_id;
1464         fc->legacy_opts_show = ctx->legacy_opts_show;
1465         fc->max_read = max_t(unsigned int, 4096, ctx->max_read);
1466         fc->destroy = ctx->destroy;
1467         fc->no_control = ctx->no_control;
1468         fc->no_force_umount = ctx->no_force_umount;
1469
1470         err = -ENOMEM;
1471         root = fuse_get_root_inode(sb, ctx->rootmode);
1472         sb->s_d_op = &fuse_root_dentry_operations;
1473         root_dentry = d_make_root(root);
1474         if (!root_dentry)
1475                 goto err_dev_free;
1476         /* Root dentry doesn't have .d_revalidate */
1477         sb->s_d_op = &fuse_dentry_operations;
1478
1479         mutex_lock(&fuse_mutex);
1480         err = -EINVAL;
1481         if (ctx->fudptr && *ctx->fudptr)
1482                 goto err_unlock;
1483
1484         err = fuse_ctl_add_conn(fc);
1485         if (err)
1486                 goto err_unlock;
1487
1488         list_add_tail(&fc->entry, &fuse_conn_list);
1489         sb->s_root = root_dentry;
1490         if (ctx->fudptr)
1491                 *ctx->fudptr = fud;
1492         mutex_unlock(&fuse_mutex);
1493         return 0;
1494
1495  err_unlock:
1496         mutex_unlock(&fuse_mutex);
1497         dput(root_dentry);
1498  err_dev_free:
1499         if (fud)
1500                 fuse_dev_free(fud);
1501  err_free_dax:
1502         if (IS_ENABLED(CONFIG_FUSE_DAX))
1503                 fuse_dax_conn_free(fc);
1504  err:
1505         return err;
1506 }
1507 EXPORT_SYMBOL_GPL(fuse_fill_super_common);
1508
1509 static int fuse_fill_super(struct super_block *sb, struct fs_context *fsc)
1510 {
1511         struct fuse_fs_context *ctx = fsc->fs_private;
1512         int err;
1513         struct fuse_conn *fc;
1514         struct fuse_mount *fm;
1515
1516         if (!ctx->file || !ctx->rootmode_present ||
1517             !ctx->user_id_present || !ctx->group_id_present)
1518                 return -EINVAL;
1519
1520         /*
1521          * Require mount to happen from the same user namespace which
1522          * opened /dev/fuse to prevent potential attacks.
1523          */
1524         err = -EINVAL;
1525         if ((ctx->file->f_op != &fuse_dev_operations) ||
1526             (ctx->file->f_cred->user_ns != sb->s_user_ns))
1527                 goto err;
1528         ctx->fudptr = &ctx->file->private_data;
1529
1530         fc = kmalloc(sizeof(*fc), GFP_KERNEL);
1531         err = -ENOMEM;
1532         if (!fc)
1533                 goto err;
1534
1535         fm = kzalloc(sizeof(*fm), GFP_KERNEL);
1536         if (!fm) {
1537                 kfree(fc);
1538                 goto err;
1539         }
1540
1541         fuse_conn_init(fc, fm, sb->s_user_ns, &fuse_dev_fiq_ops, NULL);
1542         fc->release = fuse_free_conn;
1543
1544         sb->s_fs_info = fm;
1545
1546         err = fuse_fill_super_common(sb, ctx);
1547         if (err)
1548                 goto err_put_conn;
1549         /* file->private_data shall be visible on all CPUs after this */
1550         smp_mb();
1551         fuse_send_init(get_fuse_mount_super(sb));
1552         return 0;
1553
1554  err_put_conn:
1555         fuse_conn_put(fc);
1556         kfree(fm);
1557         sb->s_fs_info = NULL;
1558  err:
1559         return err;
1560 }
1561
1562 static int fuse_get_tree(struct fs_context *fsc)
1563 {
1564         struct fuse_fs_context *ctx = fsc->fs_private;
1565         int err;
1566
1567         if (ctx->fd_present)
1568                 ctx->file = fget(ctx->fd);
1569
1570         if (IS_ENABLED(CONFIG_BLOCK) && ctx->is_bdev) {
1571                 err = get_tree_bdev(fsc, fuse_fill_super);
1572                 goto out_fput;
1573         }
1574
1575         err = get_tree_nodev(fsc, fuse_fill_super);
1576 out_fput:
1577         if (ctx->file)
1578                 fput(ctx->file);
1579         return err;
1580 }
1581
1582 static const struct fs_context_operations fuse_context_ops = {
1583         .free           = fuse_free_fsc,
1584         .parse_param    = fuse_parse_param,
1585         .reconfigure    = fuse_reconfigure,
1586         .get_tree       = fuse_get_tree,
1587 };
1588
1589 /*
1590  * Set up the filesystem mount context.
1591  */
1592 static int fuse_init_fs_context(struct fs_context *fsc)
1593 {
1594         struct fuse_fs_context *ctx;
1595
1596         ctx = kzalloc(sizeof(struct fuse_fs_context), GFP_KERNEL);
1597         if (!ctx)
1598                 return -ENOMEM;
1599
1600         ctx->max_read = ~0;
1601         ctx->blksize = FUSE_DEFAULT_BLKSIZE;
1602         ctx->legacy_opts_show = true;
1603
1604 #ifdef CONFIG_BLOCK
1605         if (fsc->fs_type == &fuseblk_fs_type) {
1606                 ctx->is_bdev = true;
1607                 ctx->destroy = true;
1608         }
1609 #endif
1610
1611         fsc->fs_private = ctx;
1612         fsc->ops = &fuse_context_ops;
1613         return 0;
1614 }
1615
1616 bool fuse_mount_remove(struct fuse_mount *fm)
1617 {
1618         struct fuse_conn *fc = fm->fc;
1619         bool last = false;
1620
1621         down_write(&fc->killsb);
1622         list_del_init(&fm->fc_entry);
1623         if (list_empty(&fc->mounts))
1624                 last = true;
1625         up_write(&fc->killsb);
1626
1627         return last;
1628 }
1629 EXPORT_SYMBOL_GPL(fuse_mount_remove);
1630
1631 void fuse_conn_destroy(struct fuse_mount *fm)
1632 {
1633         struct fuse_conn *fc = fm->fc;
1634
1635         if (fc->destroy)
1636                 fuse_send_destroy(fm);
1637
1638         fuse_abort_conn(fc);
1639         fuse_wait_aborted(fc);
1640
1641         if (!list_empty(&fc->entry)) {
1642                 mutex_lock(&fuse_mutex);
1643                 list_del(&fc->entry);
1644                 fuse_ctl_remove_conn(fc);
1645                 mutex_unlock(&fuse_mutex);
1646         }
1647 }
1648 EXPORT_SYMBOL_GPL(fuse_conn_destroy);
1649
1650 static void fuse_sb_destroy(struct super_block *sb)
1651 {
1652         struct fuse_mount *fm = get_fuse_mount_super(sb);
1653         bool last;
1654
1655         if (fm) {
1656                 last = fuse_mount_remove(fm);
1657                 if (last)
1658                         fuse_conn_destroy(fm);
1659         }
1660 }
1661
1662 static void fuse_kill_sb_anon(struct super_block *sb)
1663 {
1664         fuse_sb_destroy(sb);
1665         kill_anon_super(sb);
1666 }
1667
1668 static struct file_system_type fuse_fs_type = {
1669         .owner          = THIS_MODULE,
1670         .name           = "fuse",
1671         .fs_flags       = FS_HAS_SUBTYPE | FS_USERNS_MOUNT,
1672         .init_fs_context = fuse_init_fs_context,
1673         .parameters     = fuse_fs_parameters,
1674         .kill_sb        = fuse_kill_sb_anon,
1675 };
1676 MODULE_ALIAS_FS("fuse");
1677
1678 #ifdef CONFIG_BLOCK
1679 static void fuse_kill_sb_blk(struct super_block *sb)
1680 {
1681         fuse_sb_destroy(sb);
1682         kill_block_super(sb);
1683 }
1684
1685 static struct file_system_type fuseblk_fs_type = {
1686         .owner          = THIS_MODULE,
1687         .name           = "fuseblk",
1688         .init_fs_context = fuse_init_fs_context,
1689         .parameters     = fuse_fs_parameters,
1690         .kill_sb        = fuse_kill_sb_blk,
1691         .fs_flags       = FS_REQUIRES_DEV | FS_HAS_SUBTYPE,
1692 };
1693 MODULE_ALIAS_FS("fuseblk");
1694
1695 static inline int register_fuseblk(void)
1696 {
1697         return register_filesystem(&fuseblk_fs_type);
1698 }
1699
1700 static inline void unregister_fuseblk(void)
1701 {
1702         unregister_filesystem(&fuseblk_fs_type);
1703 }
1704 #else
1705 static inline int register_fuseblk(void)
1706 {
1707         return 0;
1708 }
1709
1710 static inline void unregister_fuseblk(void)
1711 {
1712 }
1713 #endif
1714
1715 static void fuse_inode_init_once(void *foo)
1716 {
1717         struct inode *inode = foo;
1718
1719         inode_init_once(inode);
1720 }
1721
1722 static int __init fuse_fs_init(void)
1723 {
1724         int err;
1725
1726         fuse_inode_cachep = kmem_cache_create("fuse_inode",
1727                         sizeof(struct fuse_inode), 0,
1728                         SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT|SLAB_RECLAIM_ACCOUNT,
1729                         fuse_inode_init_once);
1730         err = -ENOMEM;
1731         if (!fuse_inode_cachep)
1732                 goto out;
1733
1734         err = register_fuseblk();
1735         if (err)
1736                 goto out2;
1737
1738         err = register_filesystem(&fuse_fs_type);
1739         if (err)
1740                 goto out3;
1741
1742         return 0;
1743
1744  out3:
1745         unregister_fuseblk();
1746  out2:
1747         kmem_cache_destroy(fuse_inode_cachep);
1748  out:
1749         return err;
1750 }
1751
1752 static void fuse_fs_cleanup(void)
1753 {
1754         unregister_filesystem(&fuse_fs_type);
1755         unregister_fuseblk();
1756
1757         /*
1758          * Make sure all delayed rcu free inodes are flushed before we
1759          * destroy cache.
1760          */
1761         rcu_barrier();
1762         kmem_cache_destroy(fuse_inode_cachep);
1763 }
1764
1765 static struct kobject *fuse_kobj;
1766
1767 static int fuse_sysfs_init(void)
1768 {
1769         int err;
1770
1771         fuse_kobj = kobject_create_and_add("fuse", fs_kobj);
1772         if (!fuse_kobj) {
1773                 err = -ENOMEM;
1774                 goto out_err;
1775         }
1776
1777         err = sysfs_create_mount_point(fuse_kobj, "connections");
1778         if (err)
1779                 goto out_fuse_unregister;
1780
1781         return 0;
1782
1783  out_fuse_unregister:
1784         kobject_put(fuse_kobj);
1785  out_err:
1786         return err;
1787 }
1788
1789 static void fuse_sysfs_cleanup(void)
1790 {
1791         sysfs_remove_mount_point(fuse_kobj, "connections");
1792         kobject_put(fuse_kobj);
1793 }
1794
1795 static int __init fuse_init(void)
1796 {
1797         int res;
1798
1799         pr_info("init (API version %i.%i)\n",
1800                 FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
1801
1802         INIT_LIST_HEAD(&fuse_conn_list);
1803         res = fuse_fs_init();
1804         if (res)
1805                 goto err;
1806
1807         res = fuse_dev_init();
1808         if (res)
1809                 goto err_fs_cleanup;
1810
1811         res = fuse_sysfs_init();
1812         if (res)
1813                 goto err_dev_cleanup;
1814
1815         res = fuse_ctl_init();
1816         if (res)
1817                 goto err_sysfs_cleanup;
1818
1819         sanitize_global_limit(&max_user_bgreq);
1820         sanitize_global_limit(&max_user_congthresh);
1821
1822         return 0;
1823
1824  err_sysfs_cleanup:
1825         fuse_sysfs_cleanup();
1826  err_dev_cleanup:
1827         fuse_dev_cleanup();
1828  err_fs_cleanup:
1829         fuse_fs_cleanup();
1830  err:
1831         return res;
1832 }
1833
1834 static void __exit fuse_exit(void)
1835 {
1836         pr_debug("exit\n");
1837
1838         fuse_ctl_cleanup();
1839         fuse_sysfs_cleanup();
1840         fuse_fs_cleanup();
1841         fuse_dev_cleanup();
1842 }
1843
1844 module_init(fuse_init);
1845 module_exit(fuse_exit);