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 *fc)
 142 {
 143         struct super_block *sb = fc->root->d_sb;
 144
 145         sync_filesystem(sb);
 146         if (fc->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 ((inode->i_mode ^ attr->mode) & S_IFMT) {
 354                 /* Inode has changed type, any I/O on the old 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 enum {
 510         OPT_SOURCE,
 511         OPT_SUBTYPE,
 512         OPT_FD,
 513         OPT_ROOTMODE,
 514         OPT_USER_ID,
 515         OPT_GROUP_ID,
 516         OPT_DEFAULT_PERMISSIONS,
 517         OPT_ALLOW_OTHER,
 518         OPT_MAX_READ,
 519         OPT_BLKSIZE,
 520         OPT_ERR
 521 };
 522
 523 static const struct fs_parameter_spec fuse_fs_parameters[] = {
 524         fsparam_string  ("source",              OPT_SOURCE),
 525         fsparam_u32     ("fd",                  OPT_FD),
 526         fsparam_u32oct  ("rootmode",            OPT_ROOTMODE),
 527         fsparam_u32     ("user_id",             OPT_USER_ID),
 528         fsparam_u32     ("group_id",            OPT_GROUP_ID),
 529         fsparam_flag    ("default_permissions", OPT_DEFAULT_PERMISSIONS),
 530         fsparam_flag    ("allow_other",         OPT_ALLOW_OTHER),
 531         fsparam_u32     ("max_read",            OPT_MAX_READ),
 532         fsparam_u32     ("blksize",             OPT_BLKSIZE),
 533         fsparam_string  ("subtype",             OPT_SUBTYPE),
 534         {}
 535 };
 536
 537 static int fuse_parse_param(struct fs_context *fc, struct fs_parameter *param)
 538 {
 539         struct fs_parse_result result;
 540         struct fuse_fs_context *ctx = fc->fs_private;
 541         int opt;
 542
 543         if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) {
 544                 /*
 545                  * Ignore options coming from mount(MS_REMOUNT) for backward
 546                  * compatibility.
 547                  */
 548                 if (fc->oldapi)
 549                         return 0;
 550
 551                 return invalfc(fc, "No changes allowed in reconfigure");
 552         }
 553
 554         opt = fs_parse(fc, fuse_fs_parameters, param, &result);
 555         if (opt < 0)
 556                 return opt;
 557
 558         switch (opt) {
 559         case OPT_SOURCE:
 560                 if (fc->source)
 561                         return invalfc(fc, "Multiple sources specified");
 562                 fc->source = param->string;
 563                 param->string = NULL;
 564                 break;
 565
 566         case OPT_SUBTYPE:
 567                 if (ctx->subtype)
 568                         return invalfc(fc, "Multiple subtypes specified");
 569                 ctx->subtype = param->string;
 570                 param->string = NULL;
 571                 return 0;
 572
 573         case OPT_FD:
 574                 ctx->fd = result.uint_32;
 575                 ctx->fd_present = true;
 576                 break;
 577
 578         case OPT_ROOTMODE:
 579                 if (!fuse_valid_type(result.uint_32))
 580                         return invalfc(fc, "Invalid rootmode");
 581                 ctx->rootmode = result.uint_32;
 582                 ctx->rootmode_present = true;
 583                 break;
 584
 585         case OPT_USER_ID:
 586                 ctx->user_id = make_kuid(fc->user_ns, result.uint_32);
 587                 if (!uid_valid(ctx->user_id))
 588                         return invalfc(fc, "Invalid user_id");
 589                 ctx->user_id_present = true;
 590                 break;
 591
 592         case OPT_GROUP_ID:
 593                 ctx->group_id = make_kgid(fc->user_ns, result.uint_32);
 594                 if (!gid_valid(ctx->group_id))
 595                         return invalfc(fc, "Invalid group_id");
 596                 ctx->group_id_present = true;
 597                 break;
 598
 599         case OPT_DEFAULT_PERMISSIONS:
 600                 ctx->default_permissions = true;
 601                 break;
 602
 603         case OPT_ALLOW_OTHER:
 604                 ctx->allow_other = true;
 605                 break;
 606
 607         case OPT_MAX_READ:
 608                 ctx->max_read = result.uint_32;
 609                 break;
 610
 611         case OPT_BLKSIZE:
 612                 if (!ctx->is_bdev)
 613                         return invalfc(fc, "blksize only supported for fuseblk");
 614                 ctx->blksize = result.uint_32;
 615                 break;
 616
 617         default:
 618                 return -EINVAL;
 619         }
 620
 621         return 0;
 622 }
 623
 624 static void fuse_free_fc(struct fs_context *fc)
 625 {
 626         struct fuse_fs_context *ctx = fc->fs_private;
 627
 628         if (ctx) {
 629                 kfree(ctx->subtype);
 630                 kfree(ctx);
 631         }
 632 }
 633
 634 static int fuse_show_options(struct seq_file *m, struct dentry *root)
 635 {
 636         struct super_block *sb = root->d_sb;
 637         struct fuse_conn *fc = get_fuse_conn_super(sb);
 638
 639         if (fc->legacy_opts_show) {
 640                 seq_printf(m, ",user_id=%u",
 641                            from_kuid_munged(fc->user_ns, fc->user_id));
 642                 seq_printf(m, ",group_id=%u",
 643                            from_kgid_munged(fc->user_ns, fc->group_id));
 644                 if (fc->default_permissions)
 645                         seq_puts(m, ",default_permissions");
 646                 if (fc->allow_other)
 647                         seq_puts(m, ",allow_other");
 648                 if (fc->max_read != ~0)
 649                         seq_printf(m, ",max_read=%u", fc->max_read);
 650                 if (sb->s_bdev && sb->s_blocksize != FUSE_DEFAULT_BLKSIZE)
 651                         seq_printf(m, ",blksize=%lu", sb->s_blocksize);
 652         }
 653 #ifdef CONFIG_FUSE_DAX
 654         if (fc->dax)
 655                 seq_puts(m, ",dax");
 656 #endif
 657
 658         return 0;
 659 }
 660
 661 static void fuse_iqueue_init(struct fuse_iqueue *fiq,
 662                              const struct fuse_iqueue_ops *ops,
 663                              void *priv)
 664 {
 665         memset(fiq, 0, sizeof(struct fuse_iqueue));
 666         spin_lock_init(&fiq->lock);
 667         init_waitqueue_head(&fiq->waitq);
 668         INIT_LIST_HEAD(&fiq->pending);
 669         INIT_LIST_HEAD(&fiq->interrupts);
 670         fiq->forget_list_tail = &fiq->forget_list_head;
 671         fiq->connected = 1;
 672         fiq->ops = ops;
 673         fiq->priv = priv;
 674 }
 675
 676 static void fuse_pqueue_init(struct fuse_pqueue *fpq)
 677 {
 678         unsigned int i;
 679
 680         spin_lock_init(&fpq->lock);
 681         for (i = 0; i < FUSE_PQ_HASH_SIZE; i++)
 682                 INIT_LIST_HEAD(&fpq->processing[i]);
 683         INIT_LIST_HEAD(&fpq->io);
 684         fpq->connected = 1;
 685 }
 686
 687 void fuse_conn_init(struct fuse_conn *fc, struct fuse_mount *fm,
 688                     struct user_namespace *user_ns,
 689                     const struct fuse_iqueue_ops *fiq_ops, void *fiq_priv)
 690 {
 691         memset(fc, 0, sizeof(*fc));
 692         spin_lock_init(&fc->lock);
 693         spin_lock_init(&fc->bg_lock);
 694         init_rwsem(&fc->killsb);
 695         refcount_set(&fc->count, 1);
 696         atomic_set(&fc->dev_count, 1);
 697         init_waitqueue_head(&fc->blocked_waitq);
 698         fuse_iqueue_init(&fc->iq, fiq_ops, fiq_priv);
 699         INIT_LIST_HEAD(&fc->bg_queue);
 700         INIT_LIST_HEAD(&fc->entry);
 701         INIT_LIST_HEAD(&fc->devices);
 702         atomic_set(&fc->num_waiting, 0);
 703         fc->max_background = FUSE_DEFAULT_MAX_BACKGROUND;
 704         fc->congestion_threshold = FUSE_DEFAULT_CONGESTION_THRESHOLD;
 705         atomic64_set(&fc->khctr, 0);
 706         fc->polled_files = RB_ROOT;
 707         fc->blocked = 0;
 708         fc->initialized = 0;
 709         fc->connected = 1;
 710         atomic64_set(&fc->attr_version, 1);
 711         get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));
 712         fc->pid_ns = get_pid_ns(task_active_pid_ns(current));
 713         fc->user_ns = get_user_ns(user_ns);
 714         fc->max_pages = FUSE_DEFAULT_MAX_PAGES_PER_REQ;
 715
 716         INIT_LIST_HEAD(&fc->mounts);
 717         list_add(&fm->fc_entry, &fc->mounts);
 718         fm->fc = fc;
 719 }
 720 EXPORT_SYMBOL_GPL(fuse_conn_init);
 721
 722 void fuse_conn_put(struct fuse_conn *fc)
 723 {
 724         if (refcount_dec_and_test(&fc->count)) {
 725                 struct fuse_iqueue *fiq = &fc->iq;
 726
 727                 if (IS_ENABLED(CONFIG_FUSE_DAX))
 728                         fuse_dax_conn_free(fc);
 729                 if (fiq->ops->release)
 730                         fiq->ops->release(fiq);
 731                 put_pid_ns(fc->pid_ns);
 732                 put_user_ns(fc->user_ns);
 733                 fc->release(fc);
 734         }
 735 }
 736 EXPORT_SYMBOL_GPL(fuse_conn_put);
 737
 738 struct fuse_conn *fuse_conn_get(struct fuse_conn *fc)
 739 {
 740         refcount_inc(&fc->count);
 741         return fc;
 742 }
 743 EXPORT_SYMBOL_GPL(fuse_conn_get);
 744
 745 static struct inode *fuse_get_root_inode(struct super_block *sb, unsigned mode)
 746 {
 747         struct fuse_attr attr;
 748         memset(&attr, 0, sizeof(attr));
 749
 750         attr.mode = mode;
 751         attr.ino = FUSE_ROOT_ID;
 752         attr.nlink = 1;
 753         return fuse_iget(sb, 1, 0, &attr, 0, 0);
 754 }
 755
 756 struct fuse_inode_handle {
 757         u64 nodeid;
 758         u32 generation;
 759 };
 760
 761 static struct dentry *fuse_get_dentry(struct super_block *sb,
 762                                       struct fuse_inode_handle *handle)
 763 {
 764         struct fuse_conn *fc = get_fuse_conn_super(sb);
 765         struct inode *inode;
 766         struct dentry *entry;
 767         int err = -ESTALE;
 768
 769         if (handle->nodeid == 0)
 770                 goto out_err;
 771
 772         inode = ilookup5(sb, handle->nodeid, fuse_inode_eq, &handle->nodeid);
 773         if (!inode) {
 774                 struct fuse_entry_out outarg;
 775                 const struct qstr name = QSTR_INIT(".", 1);
 776
 777                 if (!fc->export_support)
 778                         goto out_err;
 779
 780                 err = fuse_lookup_name(sb, handle->nodeid, &name, &outarg,
 781                                        &inode);
 782                 if (err && err != -ENOENT)
 783                         goto out_err;
 784                 if (err || !inode) {
 785                         err = -ESTALE;
 786                         goto out_err;
 787                 }
 788                 err = -EIO;
 789                 if (get_node_id(inode) != handle->nodeid)
 790                         goto out_iput;
 791         }
 792         err = -ESTALE;
 793         if (inode->i_generation != handle->generation)
 794                 goto out_iput;
 795
 796         entry = d_obtain_alias(inode);
 797         if (!IS_ERR(entry) && get_node_id(inode) != FUSE_ROOT_ID)
 798                 fuse_invalidate_entry_cache(entry);
 799
 800         return entry;
 801
 802  out_iput:
 803         iput(inode);
 804  out_err:
 805         return ERR_PTR(err);
 806 }
 807
 808 static int fuse_encode_fh(struct inode *inode, u32 *fh, int *max_len,
 809                            struct inode *parent)
 810 {
 811         int len = parent ? 6 : 3;
 812         u64 nodeid;
 813         u32 generation;
 814
 815         if (*max_len < len) {
 816                 *max_len = len;
 817                 return  FILEID_INVALID;
 818         }
 819
 820         nodeid = get_fuse_inode(inode)->nodeid;
 821         generation = inode->i_generation;
 822
 823         fh[0] = (u32)(nodeid >> 32);
 824         fh[1] = (u32)(nodeid & 0xffffffff);
 825         fh[2] = generation;
 826
 827         if (parent) {
 828                 nodeid = get_fuse_inode(parent)->nodeid;
 829                 generation = parent->i_generation;
 830
 831                 fh[3] = (u32)(nodeid >> 32);
 832                 fh[4] = (u32)(nodeid & 0xffffffff);
 833                 fh[5] = generation;
 834         }
 835
 836         *max_len = len;
 837         return parent ? 0x82 : 0x81;
 838 }
 839
 840 static struct dentry *fuse_fh_to_dentry(struct super_block *sb,
 841                 struct fid *fid, int fh_len, int fh_type)
 842 {
 843         struct fuse_inode_handle handle;
 844
 845         if ((fh_type != 0x81 && fh_type != 0x82) || fh_len < 3)
 846                 return NULL;
 847
 848         handle.nodeid = (u64) fid->raw[0] << 32;
 849         handle.nodeid |= (u64) fid->raw[1];
 850         handle.generation = fid->raw[2];
 851         return fuse_get_dentry(sb, &handle);
 852 }
 853
 854 static struct dentry *fuse_fh_to_parent(struct super_block *sb,
 855                 struct fid *fid, int fh_len, int fh_type)
 856 {
 857         struct fuse_inode_handle parent;
 858
 859         if (fh_type != 0x82 || fh_len < 6)
 860                 return NULL;
 861
 862         parent.nodeid = (u64) fid->raw[3] << 32;
 863         parent.nodeid |= (u64) fid->raw[4];
 864         parent.generation = fid->raw[5];
 865         return fuse_get_dentry(sb, &parent);
 866 }
 867
 868 static struct dentry *fuse_get_parent(struct dentry *child)
 869 {
 870         struct inode *child_inode = d_inode(child);
 871         struct fuse_conn *fc = get_fuse_conn(child_inode);
 872         struct inode *inode;
 873         struct dentry *parent;
 874         struct fuse_entry_out outarg;
 875         const struct qstr name = QSTR_INIT("..", 2);
 876         int err;
 877
 878         if (!fc->export_support)
 879                 return ERR_PTR(-ESTALE);
 880
 881         err = fuse_lookup_name(child_inode->i_sb, get_node_id(child_inode),
 882                                &name, &outarg, &inode);
 883         if (err) {
 884                 if (err == -ENOENT)
 885                         return ERR_PTR(-ESTALE);
 886                 return ERR_PTR(err);
 887         }
 888
 889         parent = d_obtain_alias(inode);
 890         if (!IS_ERR(parent) && get_node_id(inode) != FUSE_ROOT_ID)
 891                 fuse_invalidate_entry_cache(parent);
 892
 893         return parent;
 894 }
 895
 896 static const struct export_operations fuse_export_operations = {
 897         .fh_to_dentry   = fuse_fh_to_dentry,
 898         .fh_to_parent   = fuse_fh_to_parent,
 899         .encode_fh      = fuse_encode_fh,
 900         .get_parent     = fuse_get_parent,
 901 };
 902
 903 static const struct super_operations fuse_super_operations = {
 904         .alloc_inode    = fuse_alloc_inode,
 905         .free_inode     = fuse_free_inode,
 906         .evict_inode    = fuse_evict_inode,
 907         .write_inode    = fuse_write_inode,
 908         .drop_inode     = generic_delete_inode,
 909         .put_super      = fuse_put_super,
 910         .umount_begin   = fuse_umount_begin,
 911         .statfs         = fuse_statfs,
 912         .show_options   = fuse_show_options,
 913 };
 914
 915 static void sanitize_global_limit(unsigned *limit)
 916 {
 917         /*
 918          * The default maximum number of async requests is calculated to consume
 919          * 1/2^13 of the total memory, assuming 392 bytes per request.
 920          */
 921         if (*limit == 0)
 922                 *limit = ((totalram_pages() << PAGE_SHIFT) >> 13) / 392;
 923
 924         if (*limit >= 1 << 16)
 925                 *limit = (1 << 16) - 1;
 926 }
 927
 928 static int set_global_limit(const char *val, const struct kernel_param *kp)
 929 {
 930         int rv;
 931
 932         rv = param_set_uint(val, kp);
 933         if (rv)
 934                 return rv;
 935
 936         sanitize_global_limit((unsigned *)kp->arg);
 937
 938         return 0;
 939 }
 940
 941 static void process_init_limits(struct fuse_conn *fc, struct fuse_init_out *arg)
 942 {
 943         int cap_sys_admin = capable(CAP_SYS_ADMIN);
 944
 945         if (arg->minor < 13)
 946                 return;
 947
 948         sanitize_global_limit(&max_user_bgreq);
 949         sanitize_global_limit(&max_user_congthresh);
 950
 951         spin_lock(&fc->bg_lock);
 952         if (arg->max_background) {
 953                 fc->max_background = arg->max_background;
 954
 955                 if (!cap_sys_admin && fc->max_background > max_user_bgreq)
 956                         fc->max_background = max_user_bgreq;
 957         }
 958         if (arg->congestion_threshold) {
 959                 fc->congestion_threshold = arg->congestion_threshold;
 960
 961                 if (!cap_sys_admin &&
 962                     fc->congestion_threshold > max_user_congthresh)
 963                         fc->congestion_threshold = max_user_congthresh;
 964         }
 965         spin_unlock(&fc->bg_lock);
 966 }
 967
 968 struct fuse_init_args {
 969         struct fuse_args args;
 970         struct fuse_init_in in;
 971         struct fuse_init_out out;
 972 };
 973
 974 static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args,
 975                                int error)
 976 {
 977         struct fuse_conn *fc = fm->fc;
 978         struct fuse_init_args *ia = container_of(args, typeof(*ia), args);
 979         struct fuse_init_out *arg = &ia->out;
 980         bool ok = true;
 981
 982         if (error || arg->major != FUSE_KERNEL_VERSION)
 983                 ok = false;
 984         else {
 985                 unsigned long ra_pages;
 986
 987                 process_init_limits(fc, arg);
 988
 989                 if (arg->minor >= 6) {
 990                         ra_pages = arg->max_readahead / PAGE_SIZE;
 991                         if (arg->flags & FUSE_ASYNC_READ)
 992                                 fc->async_read = 1;
 993                         if (!(arg->flags & FUSE_POSIX_LOCKS))
 994                                 fc->no_lock = 1;
 995                         if (arg->minor >= 17) {
 996                                 if (!(arg->flags & FUSE_FLOCK_LOCKS))
 997                                         fc->no_flock = 1;
 998                         } else {
 999                                 if (!(arg->flags & FUSE_POSIX_LOCKS))
1000                                         fc->no_flock = 1;
1001                         }
1002                         if (arg->flags & FUSE_ATOMIC_O_TRUNC)
1003                                 fc->atomic_o_trunc = 1;
1004                         if (arg->minor >= 9) {
1005                                 /* LOOKUP has dependency on proto version */
1006                                 if (arg->flags & FUSE_EXPORT_SUPPORT)
1007                                         fc->export_support = 1;
1008                         }
1009                         if (arg->flags & FUSE_BIG_WRITES)
1010                                 fc->big_writes = 1;
1011                         if (arg->flags & FUSE_DONT_MASK)
1012                                 fc->dont_mask = 1;
1013                         if (arg->flags & FUSE_AUTO_INVAL_DATA)
1014                                 fc->auto_inval_data = 1;
1015                         else if (arg->flags & FUSE_EXPLICIT_INVAL_DATA)
1016                                 fc->explicit_inval_data = 1;
1017                         if (arg->flags & FUSE_DO_READDIRPLUS) {
1018                                 fc->do_readdirplus = 1;
1019                                 if (arg->flags & FUSE_READDIRPLUS_AUTO)
1020                                         fc->readdirplus_auto = 1;
1021                         }
1022                         if (arg->flags & FUSE_ASYNC_DIO)
1023                                 fc->async_dio = 1;
1024                         if (arg->flags & FUSE_WRITEBACK_CACHE)
1025                                 fc->writeback_cache = 1;
1026                         if (arg->flags & FUSE_PARALLEL_DIROPS)
1027                                 fc->parallel_dirops = 1;
1028                         if (arg->flags & FUSE_HANDLE_KILLPRIV)
1029                                 fc->handle_killpriv = 1;
1030                         if (arg->time_gran && arg->time_gran <= 1000000000)
1031                                 fm->sb->s_time_gran = arg->time_gran;
1032                         if ((arg->flags & FUSE_POSIX_ACL)) {
1033                                 fc->default_permissions = 1;
1034                                 fc->posix_acl = 1;
1035                                 fm->sb->s_xattr = fuse_acl_xattr_handlers;
1036                         }
1037                         if (arg->flags & FUSE_CACHE_SYMLINKS)
1038                                 fc->cache_symlinks = 1;
1039                         if (arg->flags & FUSE_ABORT_ERROR)
1040                                 fc->abort_err = 1;
1041                         if (arg->flags & FUSE_MAX_PAGES) {
1042                                 fc->max_pages =
1043                                         min_t(unsigned int, FUSE_MAX_MAX_PAGES,
1044                                         max_t(unsigned int, arg->max_pages, 1));
1045                         }
1046                         if (IS_ENABLED(CONFIG_FUSE_DAX) &&
1047                             arg->flags & FUSE_MAP_ALIGNMENT &&
1048                             !fuse_dax_check_alignment(fc, arg->map_alignment)) {
1049                                 ok = false;
1050                         }
1051                         if (arg->flags & FUSE_HANDLE_KILLPRIV_V2) {
1052                                 fc->handle_killpriv_v2 = 1;
1053                                 fm->sb->s_flags |= SB_NOSEC;
1054                         }
1055                 } else {
1056                         ra_pages = fc->max_read / PAGE_SIZE;
1057                         fc->no_lock = 1;
1058                         fc->no_flock = 1;
1059                 }
1060
1061                 fm->sb->s_bdi->ra_pages =
1062                                 min(fm->sb->s_bdi->ra_pages, ra_pages);
1063                 fc->minor = arg->minor;
1064                 fc->max_write = arg->minor < 5 ? 4096 : arg->max_write;
1065                 fc->max_write = max_t(unsigned, 4096, fc->max_write);
1066                 fc->conn_init = 1;
1067         }
1068         kfree(ia);
1069
1070         if (!ok) {
1071                 fc->conn_init = 0;
1072                 fc->conn_error = 1;
1073         }
1074
1075         fuse_set_initialized(fc);
1076         wake_up_all(&fc->blocked_waitq);
1077 }
1078
1079 void fuse_send_init(struct fuse_mount *fm)
1080 {
1081         struct fuse_init_args *ia;
1082
1083         ia = kzalloc(sizeof(*ia), GFP_KERNEL | __GFP_NOFAIL);
1084
1085         ia->in.major = FUSE_KERNEL_VERSION;
1086         ia->in.minor = FUSE_KERNEL_MINOR_VERSION;
1087         ia->in.max_readahead = fm->sb->s_bdi->ra_pages * PAGE_SIZE;
1088         ia->in.flags |=
1089                 FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |
1090                 FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES | FUSE_DONT_MASK |
1091                 FUSE_SPLICE_WRITE | FUSE_SPLICE_MOVE | FUSE_SPLICE_READ |
1092                 FUSE_FLOCK_LOCKS | FUSE_HAS_IOCTL_DIR | FUSE_AUTO_INVAL_DATA |
1093                 FUSE_DO_READDIRPLUS | FUSE_READDIRPLUS_AUTO | FUSE_ASYNC_DIO |
1094                 FUSE_WRITEBACK_CACHE | FUSE_NO_OPEN_SUPPORT |
1095                 FUSE_PARALLEL_DIROPS | FUSE_HANDLE_KILLPRIV | FUSE_POSIX_ACL |
1096                 FUSE_ABORT_ERROR | FUSE_MAX_PAGES | FUSE_CACHE_SYMLINKS |
1097                 FUSE_NO_OPENDIR_SUPPORT | FUSE_EXPLICIT_INVAL_DATA |
1098                 FUSE_HANDLE_KILLPRIV_V2;
1099 #ifdef CONFIG_FUSE_DAX
1100         if (fm->fc->dax)
1101                 ia->in.flags |= FUSE_MAP_ALIGNMENT;
1102 #endif
1103         if (fm->fc->auto_submounts)
1104                 ia->in.flags |= FUSE_SUBMOUNTS;
1105
1106         ia->args.opcode = FUSE_INIT;
1107         ia->args.in_numargs = 1;
1108         ia->args.in_args[0].size = sizeof(ia->in);
1109         ia->args.in_args[0].value = &ia->in;
1110         ia->args.out_numargs = 1;
1111         /* Variable length argument used for backward compatibility
1112            with interface version < 7.5.  Rest of init_out is zeroed
1113            by do_get_request(), so a short reply is not a problem */
1114         ia->args.out_argvar = true;
1115         ia->args.out_args[0].size = sizeof(ia->out);
1116         ia->args.out_args[0].value = &ia->out;
1117         ia->args.force = true;
1118         ia->args.nocreds = true;
1119         ia->args.end = process_init_reply;
1120
1121         if (fuse_simple_background(fm, &ia->args, GFP_KERNEL) != 0)
1122                 process_init_reply(fm, &ia->args, -ENOTCONN);
1123 }
1124 EXPORT_SYMBOL_GPL(fuse_send_init);
1125
1126 void fuse_free_conn(struct fuse_conn *fc)
1127 {
1128         WARN_ON(!list_empty(&fc->devices));
1129         kfree_rcu(fc, rcu);
1130 }
1131 EXPORT_SYMBOL_GPL(fuse_free_conn);
1132
1133 static int fuse_bdi_init(struct fuse_conn *fc, struct super_block *sb)
1134 {
1135         int err;
1136         char *suffix = "";
1137
1138         if (sb->s_bdev) {
1139                 suffix = "-fuseblk";
1140                 /*
1141                  * sb->s_bdi points to blkdev's bdi however we want to redirect
1142                  * it to our private bdi...
1143                  */
1144                 bdi_put(sb->s_bdi);
1145                 sb->s_bdi = &noop_backing_dev_info;
1146         }
1147         err = super_setup_bdi_name(sb, "%u:%u%s", MAJOR(fc->dev),
1148                                    MINOR(fc->dev), suffix);
1149         if (err)
1150                 return err;
1151
1152         /* fuse does it's own writeback accounting */
1153         sb->s_bdi->capabilities &= ~BDI_CAP_WRITEBACK_ACCT;
1154         sb->s_bdi->capabilities |= BDI_CAP_STRICTLIMIT;
1155
1156         /*
1157          * For a single fuse filesystem use max 1% of dirty +
1158          * writeback threshold.
1159          *
1160          * This gives about 1M of write buffer for memory maps on a
1161          * machine with 1G and 10% dirty_ratio, which should be more
1162          * than enough.
1163          *
1164          * Privileged users can raise it by writing to
1165          *
1166          *    /sys/class/bdi/<bdi>/max_ratio
1167          */
1168         bdi_set_max_ratio(sb->s_bdi, 1);
1169
1170         return 0;
1171 }
1172
1173 struct fuse_dev *fuse_dev_alloc(void)
1174 {
1175         struct fuse_dev *fud;
1176         struct list_head *pq;
1177
1178         fud = kzalloc(sizeof(struct fuse_dev), GFP_KERNEL);
1179         if (!fud)
1180                 return NULL;
1181
1182         pq = kcalloc(FUSE_PQ_HASH_SIZE, sizeof(struct list_head), GFP_KERNEL);
1183         if (!pq) {
1184                 kfree(fud);
1185                 return NULL;
1186         }
1187
1188         fud->pq.processing = pq;
1189         fuse_pqueue_init(&fud->pq);
1190
1191         return fud;
1192 }
1193 EXPORT_SYMBOL_GPL(fuse_dev_alloc);
1194
1195 void fuse_dev_install(struct fuse_dev *fud, struct fuse_conn *fc)
1196 {
1197         fud->fc = fuse_conn_get(fc);
1198         spin_lock(&fc->lock);
1199         list_add_tail(&fud->entry, &fc->devices);
1200         spin_unlock(&fc->lock);
1201 }
1202 EXPORT_SYMBOL_GPL(fuse_dev_install);
1203
1204 struct fuse_dev *fuse_dev_alloc_install(struct fuse_conn *fc)
1205 {
1206         struct fuse_dev *fud;
1207
1208         fud = fuse_dev_alloc();
1209         if (!fud)
1210                 return NULL;
1211
1212         fuse_dev_install(fud, fc);
1213         return fud;
1214 }
1215 EXPORT_SYMBOL_GPL(fuse_dev_alloc_install);
1216
1217 void fuse_dev_free(struct fuse_dev *fud)
1218 {
1219         struct fuse_conn *fc = fud->fc;
1220
1221         if (fc) {
1222                 spin_lock(&fc->lock);
1223                 list_del(&fud->entry);
1224                 spin_unlock(&fc->lock);
1225
1226                 fuse_conn_put(fc);
1227         }
1228         kfree(fud->pq.processing);
1229         kfree(fud);
1230 }
1231 EXPORT_SYMBOL_GPL(fuse_dev_free);
1232
1233 static void fuse_fill_attr_from_inode(struct fuse_attr *attr,
1234                                       const struct fuse_inode *fi)
1235 {
1236         *attr = (struct fuse_attr){
1237                 .ino            = fi->inode.i_ino,
1238                 .size           = fi->inode.i_size,
1239                 .blocks         = fi->inode.i_blocks,
1240                 .atime          = fi->inode.i_atime.tv_sec,
1241                 .mtime          = fi->inode.i_mtime.tv_sec,
1242                 .ctime          = fi->inode.i_ctime.tv_sec,
1243                 .atimensec      = fi->inode.i_atime.tv_nsec,
1244                 .mtimensec      = fi->inode.i_mtime.tv_nsec,
1245                 .ctimensec      = fi->inode.i_ctime.tv_nsec,
1246                 .mode           = fi->inode.i_mode,
1247                 .nlink          = fi->inode.i_nlink,
1248                 .uid            = fi->inode.i_uid.val,
1249                 .gid            = fi->inode.i_gid.val,
1250                 .rdev           = fi->inode.i_rdev,
1251                 .blksize        = 1u << fi->inode.i_blkbits,
1252         };
1253 }
1254
1255 static void fuse_sb_defaults(struct super_block *sb)
1256 {
1257         sb->s_magic = FUSE_SUPER_MAGIC;
1258         sb->s_op = &fuse_super_operations;
1259         sb->s_xattr = fuse_xattr_handlers;
1260         sb->s_maxbytes = MAX_LFS_FILESIZE;
1261         sb->s_time_gran = 1;
1262         sb->s_export_op = &fuse_export_operations;
1263         sb->s_iflags |= SB_I_IMA_UNVERIFIABLE_SIGNATURE;
1264         if (sb->s_user_ns != &init_user_ns)
1265                 sb->s_iflags |= SB_I_UNTRUSTED_MOUNTER;
1266         sb->s_flags &= ~(SB_NOSEC | SB_I_VERSION);
1267
1268         /*
1269          * If we are not in the initial user namespace posix
1270          * acls must be translated.
1271          */
1272         if (sb->s_user_ns != &init_user_ns)
1273                 sb->s_xattr = fuse_no_acl_xattr_handlers;
1274 }
1275
1276 int fuse_fill_super_submount(struct super_block *sb,
1277                              struct fuse_inode *parent_fi)
1278 {
1279         struct fuse_mount *fm = get_fuse_mount_super(sb);
1280         struct super_block *parent_sb = parent_fi->inode.i_sb;
1281         struct fuse_attr root_attr;
1282         struct inode *root;
1283
1284         fuse_sb_defaults(sb);
1285         fm->sb = sb;
1286
1287         WARN_ON(sb->s_bdi != &noop_backing_dev_info);
1288         sb->s_bdi = bdi_get(parent_sb->s_bdi);
1289
1290         sb->s_xattr = parent_sb->s_xattr;
1291         sb->s_time_gran = parent_sb->s_time_gran;
1292         sb->s_blocksize = parent_sb->s_blocksize;
1293         sb->s_blocksize_bits = parent_sb->s_blocksize_bits;
1294         sb->s_subtype = kstrdup(parent_sb->s_subtype, GFP_KERNEL);
1295         if (parent_sb->s_subtype && !sb->s_subtype)
1296                 return -ENOMEM;
1297
1298         fuse_fill_attr_from_inode(&root_attr, parent_fi);
1299         root = fuse_iget(sb, parent_fi->nodeid, 0, &root_attr, 0, 0);
1300         /*
1301          * This inode is just a duplicate, so it is not looked up and
1302          * its nlookup should not be incremented.  fuse_iget() does
1303          * that, though, so undo it here.
1304          */
1305         get_fuse_inode(root)->nlookup--;
1306         sb->s_d_op = &fuse_dentry_operations;
1307         sb->s_root = d_make_root(root);
1308         if (!sb->s_root)
1309                 return -ENOMEM;
1310
1311         return 0;
1312 }
1313
1314 int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx)
1315 {
1316         struct fuse_dev *fud = NULL;
1317         struct fuse_mount *fm = get_fuse_mount_super(sb);
1318         struct fuse_conn *fc = fm->fc;
1319         struct inode *root;
1320         struct dentry *root_dentry;
1321         int err;
1322
1323         err = -EINVAL;
1324         if (sb->s_flags & SB_MANDLOCK)
1325                 goto err;
1326
1327         fuse_sb_defaults(sb);
1328
1329         if (ctx->is_bdev) {
1330 #ifdef CONFIG_BLOCK
1331                 err = -EINVAL;
1332                 if (!sb_set_blocksize(sb, ctx->blksize))
1333                         goto err;
1334 #endif
1335         } else {
1336                 sb->s_blocksize = PAGE_SIZE;
1337                 sb->s_blocksize_bits = PAGE_SHIFT;
1338         }
1339
1340         sb->s_subtype = ctx->subtype;
1341         ctx->subtype = NULL;
1342         if (IS_ENABLED(CONFIG_FUSE_DAX)) {
1343                 err = fuse_dax_conn_alloc(fc, ctx->dax_dev);
1344                 if (err)
1345                         goto err;
1346         }
1347
1348         if (ctx->fudptr) {
1349                 err = -ENOMEM;
1350                 fud = fuse_dev_alloc_install(fc);
1351                 if (!fud)
1352                         goto err_free_dax;
1353         }
1354
1355         fc->dev = sb->s_dev;
1356         fm->sb = sb;
1357         err = fuse_bdi_init(fc, sb);
1358         if (err)
1359                 goto err_dev_free;
1360
1361         /* Handle umasking inside the fuse code */
1362         if (sb->s_flags & SB_POSIXACL)
1363                 fc->dont_mask = 1;
1364         sb->s_flags |= SB_POSIXACL;
1365
1366         fc->default_permissions = ctx->default_permissions;
1367         fc->allow_other = ctx->allow_other;
1368         fc->user_id = ctx->user_id;
1369         fc->group_id = ctx->group_id;
1370         fc->legacy_opts_show = ctx->legacy_opts_show;
1371         fc->max_read = max_t(unsigned int, 4096, ctx->max_read);
1372         fc->destroy = ctx->destroy;
1373         fc->no_control = ctx->no_control;
1374         fc->no_force_umount = ctx->no_force_umount;
1375
1376         err = -ENOMEM;
1377         root = fuse_get_root_inode(sb, ctx->rootmode);
1378         sb->s_d_op = &fuse_root_dentry_operations;
1379         root_dentry = d_make_root(root);
1380         if (!root_dentry)
1381                 goto err_dev_free;
1382         /* Root dentry doesn't have .d_revalidate */
1383         sb->s_d_op = &fuse_dentry_operations;
1384
1385         mutex_lock(&fuse_mutex);
1386         err = -EINVAL;
1387         if (ctx->fudptr && *ctx->fudptr)
1388                 goto err_unlock;
1389
1390         err = fuse_ctl_add_conn(fc);
1391         if (err)
1392                 goto err_unlock;
1393
1394         list_add_tail(&fc->entry, &fuse_conn_list);
1395         sb->s_root = root_dentry;
1396         if (ctx->fudptr)
1397                 *ctx->fudptr = fud;
1398         mutex_unlock(&fuse_mutex);
1399         return 0;
1400
1401  err_unlock:
1402         mutex_unlock(&fuse_mutex);
1403         dput(root_dentry);
1404  err_dev_free:
1405         if (fud)
1406                 fuse_dev_free(fud);
1407  err_free_dax:
1408         if (IS_ENABLED(CONFIG_FUSE_DAX))
1409                 fuse_dax_conn_free(fc);
1410  err:
1411         return err;
1412 }
1413 EXPORT_SYMBOL_GPL(fuse_fill_super_common);
1414
1415 static int fuse_fill_super(struct super_block *sb, struct fs_context *fsc)
1416 {
1417         struct fuse_fs_context *ctx = fsc->fs_private;
1418         struct file *file;
1419         int err;
1420         struct fuse_conn *fc;
1421         struct fuse_mount *fm;
1422
1423         err = -EINVAL;
1424         file = fget(ctx->fd);
1425         if (!file)
1426                 goto err;
1427
1428         /*
1429          * Require mount to happen from the same user namespace which
1430          * opened /dev/fuse to prevent potential attacks.
1431          */
1432         if ((file->f_op != &fuse_dev_operations) ||
1433             (file->f_cred->user_ns != sb->s_user_ns))
1434                 goto err_fput;
1435         ctx->fudptr = &file->private_data;
1436
1437         fc = kmalloc(sizeof(*fc), GFP_KERNEL);
1438         err = -ENOMEM;
1439         if (!fc)
1440                 goto err_fput;
1441
1442         fm = kzalloc(sizeof(*fm), GFP_KERNEL);
1443         if (!fm) {
1444                 kfree(fc);
1445                 goto err_fput;
1446         }
1447
1448         fuse_conn_init(fc, fm, sb->s_user_ns, &fuse_dev_fiq_ops, NULL);
1449         fc->release = fuse_free_conn;
1450
1451         sb->s_fs_info = fm;
1452
1453         err = fuse_fill_super_common(sb, ctx);
1454         if (err)
1455                 goto err_put_conn;
1456         /*
1457          * atomic_dec_and_test() in fput() provides the necessary
1458          * memory barrier for file->private_data to be visible on all
1459          * CPUs after this
1460          */
1461         fput(file);
1462         fuse_send_init(get_fuse_mount_super(sb));
1463         return 0;
1464
1465  err_put_conn:
1466         fuse_conn_put(fc);
1467         kfree(fm);
1468         sb->s_fs_info = NULL;
1469  err_fput:
1470         fput(file);
1471  err:
1472         return err;
1473 }
1474
1475 static int fuse_get_tree(struct fs_context *fc)
1476 {
1477         struct fuse_fs_context *ctx = fc->fs_private;
1478
1479         if (!ctx->fd_present || !ctx->rootmode_present ||
1480             !ctx->user_id_present || !ctx->group_id_present)
1481                 return -EINVAL;
1482
1483 #ifdef CONFIG_BLOCK
1484         if (ctx->is_bdev)
1485                 return get_tree_bdev(fc, fuse_fill_super);
1486 #endif
1487
1488         return get_tree_nodev(fc, fuse_fill_super);
1489 }
1490
1491 static const struct fs_context_operations fuse_context_ops = {
1492         .free           = fuse_free_fc,
1493         .parse_param    = fuse_parse_param,
1494         .reconfigure    = fuse_reconfigure,
1495         .get_tree       = fuse_get_tree,
1496 };
1497
1498 /*
1499  * Set up the filesystem mount context.
1500  */
1501 static int fuse_init_fs_context(struct fs_context *fc)
1502 {
1503         struct fuse_fs_context *ctx;
1504
1505         ctx = kzalloc(sizeof(struct fuse_fs_context), GFP_KERNEL);
1506         if (!ctx)
1507                 return -ENOMEM;
1508
1509         ctx->max_read = ~0;
1510         ctx->blksize = FUSE_DEFAULT_BLKSIZE;
1511         ctx->legacy_opts_show = true;
1512
1513 #ifdef CONFIG_BLOCK
1514         if (fc->fs_type == &fuseblk_fs_type) {
1515                 ctx->is_bdev = true;
1516                 ctx->destroy = true;
1517         }
1518 #endif
1519
1520         fc->fs_private = ctx;
1521         fc->ops = &fuse_context_ops;
1522         return 0;
1523 }
1524
1525 bool fuse_mount_remove(struct fuse_mount *fm)
1526 {
1527         struct fuse_conn *fc = fm->fc;
1528         bool last = false;
1529
1530         down_write(&fc->killsb);
1531         list_del_init(&fm->fc_entry);
1532         if (list_empty(&fc->mounts))
1533                 last = true;
1534         up_write(&fc->killsb);
1535
1536         return last;
1537 }
1538 EXPORT_SYMBOL_GPL(fuse_mount_remove);
1539
1540 void fuse_conn_destroy(struct fuse_mount *fm)
1541 {
1542         struct fuse_conn *fc = fm->fc;
1543
1544         if (fc->destroy)
1545                 fuse_send_destroy(fm);
1546
1547         fuse_abort_conn(fc);
1548         fuse_wait_aborted(fc);
1549
1550         if (!list_empty(&fc->entry)) {
1551                 mutex_lock(&fuse_mutex);
1552                 list_del(&fc->entry);
1553                 fuse_ctl_remove_conn(fc);
1554                 mutex_unlock(&fuse_mutex);
1555         }
1556 }
1557 EXPORT_SYMBOL_GPL(fuse_conn_destroy);
1558
1559 static void fuse_sb_destroy(struct super_block *sb)
1560 {
1561         struct fuse_mount *fm = get_fuse_mount_super(sb);
1562         bool last;
1563
1564         if (fm) {
1565                 last = fuse_mount_remove(fm);
1566                 if (last)
1567                         fuse_conn_destroy(fm);
1568         }
1569 }
1570
1571 static void fuse_kill_sb_anon(struct super_block *sb)
1572 {
1573         fuse_sb_destroy(sb);
1574         kill_anon_super(sb);
1575 }
1576
1577 static struct file_system_type fuse_fs_type = {
1578         .owner          = THIS_MODULE,
1579         .name           = "fuse",
1580         .fs_flags       = FS_HAS_SUBTYPE | FS_USERNS_MOUNT,
1581         .init_fs_context = fuse_init_fs_context,
1582         .parameters     = fuse_fs_parameters,
1583         .kill_sb        = fuse_kill_sb_anon,
1584 };
1585 MODULE_ALIAS_FS("fuse");
1586
1587 #ifdef CONFIG_BLOCK
1588 static void fuse_kill_sb_blk(struct super_block *sb)
1589 {
1590         fuse_sb_destroy(sb);
1591         kill_block_super(sb);
1592 }
1593
1594 static struct file_system_type fuseblk_fs_type = {
1595         .owner          = THIS_MODULE,
1596         .name           = "fuseblk",
1597         .init_fs_context = fuse_init_fs_context,
1598         .parameters     = fuse_fs_parameters,
1599         .kill_sb        = fuse_kill_sb_blk,
1600         .fs_flags       = FS_REQUIRES_DEV | FS_HAS_SUBTYPE,
1601 };
1602 MODULE_ALIAS_FS("fuseblk");
1603
1604 static inline int register_fuseblk(void)
1605 {
1606         return register_filesystem(&fuseblk_fs_type);
1607 }
1608
1609 static inline void unregister_fuseblk(void)
1610 {
1611         unregister_filesystem(&fuseblk_fs_type);
1612 }
1613 #else
1614 static inline int register_fuseblk(void)
1615 {
1616         return 0;
1617 }
1618
1619 static inline void unregister_fuseblk(void)
1620 {
1621 }
1622 #endif
1623
1624 static void fuse_inode_init_once(void *foo)
1625 {
1626         struct inode *inode = foo;
1627
1628         inode_init_once(inode);
1629 }
1630
1631 static int __init fuse_fs_init(void)
1632 {
1633         int err;
1634
1635         fuse_inode_cachep = kmem_cache_create("fuse_inode",
1636                         sizeof(struct fuse_inode), 0,
1637                         SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT|SLAB_RECLAIM_ACCOUNT,
1638                         fuse_inode_init_once);
1639         err = -ENOMEM;
1640         if (!fuse_inode_cachep)
1641                 goto out;
1642
1643         err = register_fuseblk();
1644         if (err)
1645                 goto out2;
1646
1647         err = register_filesystem(&fuse_fs_type);
1648         if (err)
1649                 goto out3;
1650
1651         return 0;
1652
1653  out3:
1654         unregister_fuseblk();
1655  out2:
1656         kmem_cache_destroy(fuse_inode_cachep);
1657  out:
1658         return err;
1659 }
1660
1661 static void fuse_fs_cleanup(void)
1662 {
1663         unregister_filesystem(&fuse_fs_type);
1664         unregister_fuseblk();
1665
1666         /*
1667          * Make sure all delayed rcu free inodes are flushed before we
1668          * destroy cache.
1669          */
1670         rcu_barrier();
1671         kmem_cache_destroy(fuse_inode_cachep);
1672 }
1673
1674 static struct kobject *fuse_kobj;
1675
1676 static int fuse_sysfs_init(void)
1677 {
1678         int err;
1679
1680         fuse_kobj = kobject_create_and_add("fuse", fs_kobj);
1681         if (!fuse_kobj) {
1682                 err = -ENOMEM;
1683                 goto out_err;
1684         }
1685
1686         err = sysfs_create_mount_point(fuse_kobj, "connections");
1687         if (err)
1688                 goto out_fuse_unregister;
1689
1690         return 0;
1691
1692  out_fuse_unregister:
1693         kobject_put(fuse_kobj);
1694  out_err:
1695         return err;
1696 }
1697
1698 static void fuse_sysfs_cleanup(void)
1699 {
1700         sysfs_remove_mount_point(fuse_kobj, "connections");
1701         kobject_put(fuse_kobj);
1702 }
1703
1704 static int __init fuse_init(void)
1705 {
1706         int res;
1707
1708         pr_info("init (API version %i.%i)\n",
1709                 FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
1710
1711         INIT_LIST_HEAD(&fuse_conn_list);
1712         res = fuse_fs_init();
1713         if (res)
1714                 goto err;
1715
1716         res = fuse_dev_init();
1717         if (res)
1718                 goto err_fs_cleanup;
1719
1720         res = fuse_sysfs_init();
1721         if (res)
1722                 goto err_dev_cleanup;
1723
1724         res = fuse_ctl_init();
1725         if (res)
1726                 goto err_sysfs_cleanup;
1727
1728         sanitize_global_limit(&max_user_bgreq);
1729         sanitize_global_limit(&max_user_congthresh);
1730
1731         return 0;
1732
1733  err_sysfs_cleanup:
1734         fuse_sysfs_cleanup();
1735  err_dev_cleanup:
1736         fuse_dev_cleanup();
1737  err_fs_cleanup:
1738         fuse_fs_cleanup();
1739  err:
1740         return res;
1741 }
1742
1743 static void __exit fuse_exit(void)
1744 {
1745         pr_debug("exit\n");
1746
1747         fuse_ctl_cleanup();
1748         fuse_sysfs_cleanup();
1749         fuse_fs_cleanup();
1750         fuse_dev_cleanup();
1751 }
1752
1753 module_init(fuse_init);
1754 module_exit(fuse_exit);