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 (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 *fc, struct fs_parameter *param) 577 { 578 struct fs_parse_result result; 579 struct fuse_fs_context *ctx = fc->fs_private; 580 int opt; 581 582 if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) { 583 /* 584 * Ignore options coming from mount(MS_REMOUNT) for backward 585 * compatibility. 586 */ 587 if (fc->oldapi) 588 return 0; 589 590 return invalfc(fc, "No changes allowed in reconfigure"); 591 } 592 593 opt = fs_parse(fc, fuse_fs_parameters, param, &result); 594 if (opt < 0) 595 return opt; 596 597 switch (opt) { 598 case OPT_SOURCE: 599 if (fc->source) 600 return invalfc(fc, "Multiple sources specified"); 601 fc->source = param->string; 602 param->string = NULL; 603 break; 604 605 case OPT_SUBTYPE: 606 if (ctx->subtype) 607 return invalfc(fc, "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(fc, "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(fc->user_ns, result.uint_32); 626 if (!uid_valid(ctx->user_id)) 627 return invalfc(fc, "Invalid user_id"); 628 ctx->user_id_present = true; 629 break; 630 631 case OPT_GROUP_ID: 632 ctx->group_id = make_kgid(fc->user_ns, result.uint_32); 633 if (!gid_valid(ctx->group_id)) 634 return invalfc(fc, "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(fc, "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_fc(struct fs_context *fc) 664 { 665 struct fuse_fs_context *ctx = fc->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 struct file *file; 1513 int err; 1514 struct fuse_conn *fc; 1515 struct fuse_mount *fm; 1516 1517 err = -EINVAL; 1518 file = fget(ctx->fd); 1519 if (!file) 1520 goto err; 1521 1522 /* 1523 * Require mount to happen from the same user namespace which 1524 * opened /dev/fuse to prevent potential attacks. 1525 */ 1526 if ((file->f_op != &fuse_dev_operations) || 1527 (file->f_cred->user_ns != sb->s_user_ns)) 1528 goto err_fput; 1529 ctx->fudptr = &file->private_data; 1530 1531 fc = kmalloc(sizeof(*fc), GFP_KERNEL); 1532 err = -ENOMEM; 1533 if (!fc) 1534 goto err_fput; 1535 1536 fm = kzalloc(sizeof(*fm), GFP_KERNEL); 1537 if (!fm) { 1538 kfree(fc); 1539 goto err_fput; 1540 } 1541 1542 fuse_conn_init(fc, fm, sb->s_user_ns, &fuse_dev_fiq_ops, NULL); 1543 fc->release = fuse_free_conn; 1544 1545 sb->s_fs_info = fm; 1546 1547 err = fuse_fill_super_common(sb, ctx); 1548 if (err) 1549 goto err_put_conn; 1550 /* 1551 * atomic_dec_and_test() in fput() provides the necessary 1552 * memory barrier for file->private_data to be visible on all 1553 * CPUs after this 1554 */ 1555 fput(file); 1556 fuse_send_init(get_fuse_mount_super(sb)); 1557 return 0; 1558 1559 err_put_conn: 1560 fuse_conn_put(fc); 1561 kfree(fm); 1562 sb->s_fs_info = NULL; 1563 err_fput: 1564 fput(file); 1565 err: 1566 return err; 1567 } 1568 1569 static int fuse_get_tree(struct fs_context *fc) 1570 { 1571 struct fuse_fs_context *ctx = fc->fs_private; 1572 1573 if (!ctx->fd_present || !ctx->rootmode_present || 1574 !ctx->user_id_present || !ctx->group_id_present) 1575 return -EINVAL; 1576 1577 #ifdef CONFIG_BLOCK 1578 if (ctx->is_bdev) 1579 return get_tree_bdev(fc, fuse_fill_super); 1580 #endif 1581 1582 return get_tree_nodev(fc, fuse_fill_super); 1583 } 1584 1585 static const struct fs_context_operations fuse_context_ops = { 1586 .free = fuse_free_fc, 1587 .parse_param = fuse_parse_param, 1588 .reconfigure = fuse_reconfigure, 1589 .get_tree = fuse_get_tree, 1590 }; 1591 1592 /* 1593 * Set up the filesystem mount context. 1594 */ 1595 static int fuse_init_fs_context(struct fs_context *fc) 1596 { 1597 struct fuse_fs_context *ctx; 1598 1599 ctx = kzalloc(sizeof(struct fuse_fs_context), GFP_KERNEL); 1600 if (!ctx) 1601 return -ENOMEM; 1602 1603 ctx->max_read = ~0; 1604 ctx->blksize = FUSE_DEFAULT_BLKSIZE; 1605 ctx->legacy_opts_show = true; 1606 1607 #ifdef CONFIG_BLOCK 1608 if (fc->fs_type == &fuseblk_fs_type) { 1609 ctx->is_bdev = true; 1610 ctx->destroy = true; 1611 } 1612 #endif 1613 1614 fc->fs_private = ctx; 1615 fc->ops = &fuse_context_ops; 1616 return 0; 1617 } 1618 1619 bool fuse_mount_remove(struct fuse_mount *fm) 1620 { 1621 struct fuse_conn *fc = fm->fc; 1622 bool last = false; 1623 1624 down_write(&fc->killsb); 1625 list_del_init(&fm->fc_entry); 1626 if (list_empty(&fc->mounts)) 1627 last = true; 1628 up_write(&fc->killsb); 1629 1630 return last; 1631 } 1632 EXPORT_SYMBOL_GPL(fuse_mount_remove); 1633 1634 void fuse_conn_destroy(struct fuse_mount *fm) 1635 { 1636 struct fuse_conn *fc = fm->fc; 1637 1638 if (fc->destroy) 1639 fuse_send_destroy(fm); 1640 1641 fuse_abort_conn(fc); 1642 fuse_wait_aborted(fc); 1643 1644 if (!list_empty(&fc->entry)) { 1645 mutex_lock(&fuse_mutex); 1646 list_del(&fc->entry); 1647 fuse_ctl_remove_conn(fc); 1648 mutex_unlock(&fuse_mutex); 1649 } 1650 } 1651 EXPORT_SYMBOL_GPL(fuse_conn_destroy); 1652 1653 static void fuse_sb_destroy(struct super_block *sb) 1654 { 1655 struct fuse_mount *fm = get_fuse_mount_super(sb); 1656 bool last; 1657 1658 if (fm) { 1659 last = fuse_mount_remove(fm); 1660 if (last) 1661 fuse_conn_destroy(fm); 1662 } 1663 } 1664 1665 static void fuse_kill_sb_anon(struct super_block *sb) 1666 { 1667 fuse_sb_destroy(sb); 1668 kill_anon_super(sb); 1669 } 1670 1671 static struct file_system_type fuse_fs_type = { 1672 .owner = THIS_MODULE, 1673 .name = "fuse", 1674 .fs_flags = FS_HAS_SUBTYPE | FS_USERNS_MOUNT, 1675 .init_fs_context = fuse_init_fs_context, 1676 .parameters = fuse_fs_parameters, 1677 .kill_sb = fuse_kill_sb_anon, 1678 }; 1679 MODULE_ALIAS_FS("fuse"); 1680 1681 #ifdef CONFIG_BLOCK 1682 static void fuse_kill_sb_blk(struct super_block *sb) 1683 { 1684 fuse_sb_destroy(sb); 1685 kill_block_super(sb); 1686 } 1687 1688 static struct file_system_type fuseblk_fs_type = { 1689 .owner = THIS_MODULE, 1690 .name = "fuseblk", 1691 .init_fs_context = fuse_init_fs_context, 1692 .parameters = fuse_fs_parameters, 1693 .kill_sb = fuse_kill_sb_blk, 1694 .fs_flags = FS_REQUIRES_DEV | FS_HAS_SUBTYPE, 1695 }; 1696 MODULE_ALIAS_FS("fuseblk"); 1697 1698 static inline int register_fuseblk(void) 1699 { 1700 return register_filesystem(&fuseblk_fs_type); 1701 } 1702 1703 static inline void unregister_fuseblk(void) 1704 { 1705 unregister_filesystem(&fuseblk_fs_type); 1706 } 1707 #else 1708 static inline int register_fuseblk(void) 1709 { 1710 return 0; 1711 } 1712 1713 static inline void unregister_fuseblk(void) 1714 { 1715 } 1716 #endif 1717 1718 static void fuse_inode_init_once(void *foo) 1719 { 1720 struct inode *inode = foo; 1721 1722 inode_init_once(inode); 1723 } 1724 1725 static int __init fuse_fs_init(void) 1726 { 1727 int err; 1728 1729 fuse_inode_cachep = kmem_cache_create("fuse_inode", 1730 sizeof(struct fuse_inode), 0, 1731 SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT|SLAB_RECLAIM_ACCOUNT, 1732 fuse_inode_init_once); 1733 err = -ENOMEM; 1734 if (!fuse_inode_cachep) 1735 goto out; 1736 1737 err = register_fuseblk(); 1738 if (err) 1739 goto out2; 1740 1741 err = register_filesystem(&fuse_fs_type); 1742 if (err) 1743 goto out3; 1744 1745 return 0; 1746 1747 out3: 1748 unregister_fuseblk(); 1749 out2: 1750 kmem_cache_destroy(fuse_inode_cachep); 1751 out: 1752 return err; 1753 } 1754 1755 static void fuse_fs_cleanup(void) 1756 { 1757 unregister_filesystem(&fuse_fs_type); 1758 unregister_fuseblk(); 1759 1760 /* 1761 * Make sure all delayed rcu free inodes are flushed before we 1762 * destroy cache. 1763 */ 1764 rcu_barrier(); 1765 kmem_cache_destroy(fuse_inode_cachep); 1766 } 1767 1768 static struct kobject *fuse_kobj; 1769 1770 static int fuse_sysfs_init(void) 1771 { 1772 int err; 1773 1774 fuse_kobj = kobject_create_and_add("fuse", fs_kobj); 1775 if (!fuse_kobj) { 1776 err = -ENOMEM; 1777 goto out_err; 1778 } 1779 1780 err = sysfs_create_mount_point(fuse_kobj, "connections"); 1781 if (err) 1782 goto out_fuse_unregister; 1783 1784 return 0; 1785 1786 out_fuse_unregister: 1787 kobject_put(fuse_kobj); 1788 out_err: 1789 return err; 1790 } 1791 1792 static void fuse_sysfs_cleanup(void) 1793 { 1794 sysfs_remove_mount_point(fuse_kobj, "connections"); 1795 kobject_put(fuse_kobj); 1796 } 1797 1798 static int __init fuse_init(void) 1799 { 1800 int res; 1801 1802 pr_info("init (API version %i.%i)\n", 1803 FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION); 1804 1805 INIT_LIST_HEAD(&fuse_conn_list); 1806 res = fuse_fs_init(); 1807 if (res) 1808 goto err; 1809 1810 res = fuse_dev_init(); 1811 if (res) 1812 goto err_fs_cleanup; 1813 1814 res = fuse_sysfs_init(); 1815 if (res) 1816 goto err_dev_cleanup; 1817 1818 res = fuse_ctl_init(); 1819 if (res) 1820 goto err_sysfs_cleanup; 1821 1822 sanitize_global_limit(&max_user_bgreq); 1823 sanitize_global_limit(&max_user_congthresh); 1824 1825 return 0; 1826 1827 err_sysfs_cleanup: 1828 fuse_sysfs_cleanup(); 1829 err_dev_cleanup: 1830 fuse_dev_cleanup(); 1831 err_fs_cleanup: 1832 fuse_fs_cleanup(); 1833 err: 1834 return res; 1835 } 1836 1837 static void __exit fuse_exit(void) 1838 { 1839 pr_debug("exit\n"); 1840 1841 fuse_ctl_cleanup(); 1842 fuse_sysfs_cleanup(); 1843 fuse_fs_cleanup(); 1844 fuse_dev_cleanup(); 1845 } 1846 1847 module_init(fuse_init); 1848 module_exit(fuse_exit); 1849