xattr.c revision 4c05141df57f4ffc1a9a28f1925434924179bfe4
1/* 2 * linux/fs/reiserfs/xattr.c 3 * 4 * Copyright (c) 2002 by Jeff Mahoney, <jeffm@suse.com> 5 * 6 */ 7 8/* 9 * In order to implement EA/ACLs in a clean, backwards compatible manner, 10 * they are implemented as files in a "private" directory. 11 * Each EA is in it's own file, with the directory layout like so (/ is assumed 12 * to be relative to fs root). Inside the /.reiserfs_priv/xattrs directory, 13 * directories named using the capital-hex form of the objectid and 14 * generation number are used. Inside each directory are individual files 15 * named with the name of the extended attribute. 16 * 17 * So, for objectid 12648430, we could have: 18 * /.reiserfs_priv/xattrs/C0FFEE.0/system.posix_acl_access 19 * /.reiserfs_priv/xattrs/C0FFEE.0/system.posix_acl_default 20 * /.reiserfs_priv/xattrs/C0FFEE.0/user.Content-Type 21 * .. or similar. 22 * 23 * The file contents are the text of the EA. The size is known based on the 24 * stat data describing the file. 25 * 26 * In the case of system.posix_acl_access and system.posix_acl_default, since 27 * these are special cases for filesystem ACLs, they are interpreted by the 28 * kernel, in addition, they are negatively and positively cached and attached 29 * to the inode so that unnecessary lookups are avoided. 30 * 31 * Locking works like so: 32 * Directory components (xattr root, xattr dir) are protectd by their i_mutex. 33 * The xattrs themselves are protected by the xattr_sem. 34 */ 35 36#include "reiserfs.h" 37#include <linux/capability.h> 38#include <linux/dcache.h> 39#include <linux/namei.h> 40#include <linux/errno.h> 41#include <linux/gfp.h> 42#include <linux/fs.h> 43#include <linux/file.h> 44#include <linux/pagemap.h> 45#include <linux/xattr.h> 46#include "xattr.h" 47#include "acl.h" 48#include <asm/uaccess.h> 49#include <net/checksum.h> 50#include <linux/stat.h> 51#include <linux/quotaops.h> 52#include <linux/security.h> 53 54#define PRIVROOT_NAME ".reiserfs_priv" 55#define XAROOT_NAME "xattrs" 56 57 58/* Helpers for inode ops. We do this so that we don't have all the VFS 59 * overhead and also for proper i_mutex annotation. 60 * dir->i_mutex must be held for all of them. */ 61#ifdef CONFIG_REISERFS_FS_XATTR 62static int xattr_create(struct inode *dir, struct dentry *dentry, int mode) 63{ 64 BUG_ON(!mutex_is_locked(&dir->i_mutex)); 65 return dir->i_op->create(dir, dentry, mode, true); 66} 67#endif 68 69static int xattr_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 70{ 71 BUG_ON(!mutex_is_locked(&dir->i_mutex)); 72 return dir->i_op->mkdir(dir, dentry, mode); 73} 74 75/* We use I_MUTEX_CHILD here to silence lockdep. It's safe because xattr 76 * mutation ops aren't called during rename or splace, which are the 77 * only other users of I_MUTEX_CHILD. It violates the ordering, but that's 78 * better than allocating another subclass just for this code. */ 79static int xattr_unlink(struct inode *dir, struct dentry *dentry) 80{ 81 int error; 82 BUG_ON(!mutex_is_locked(&dir->i_mutex)); 83 84 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD); 85 error = dir->i_op->unlink(dir, dentry); 86 mutex_unlock(&dentry->d_inode->i_mutex); 87 88 if (!error) 89 d_delete(dentry); 90 return error; 91} 92 93static int xattr_rmdir(struct inode *dir, struct dentry *dentry) 94{ 95 int error; 96 BUG_ON(!mutex_is_locked(&dir->i_mutex)); 97 98 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD); 99 error = dir->i_op->rmdir(dir, dentry); 100 if (!error) 101 dentry->d_inode->i_flags |= S_DEAD; 102 mutex_unlock(&dentry->d_inode->i_mutex); 103 if (!error) 104 d_delete(dentry); 105 106 return error; 107} 108 109#define xattr_may_create(flags) (!flags || flags & XATTR_CREATE) 110 111static struct dentry *open_xa_root(struct super_block *sb, int flags) 112{ 113 struct dentry *privroot = REISERFS_SB(sb)->priv_root; 114 struct dentry *xaroot; 115 if (!privroot->d_inode) 116 return ERR_PTR(-ENODATA); 117 118 mutex_lock_nested(&privroot->d_inode->i_mutex, I_MUTEX_XATTR); 119 120 xaroot = dget(REISERFS_SB(sb)->xattr_root); 121 if (!xaroot) 122 xaroot = ERR_PTR(-ENODATA); 123 else if (!xaroot->d_inode) { 124 int err = -ENODATA; 125 if (xattr_may_create(flags)) 126 err = xattr_mkdir(privroot->d_inode, xaroot, 0700); 127 if (err) { 128 dput(xaroot); 129 xaroot = ERR_PTR(err); 130 } 131 } 132 133 mutex_unlock(&privroot->d_inode->i_mutex); 134 return xaroot; 135} 136 137static struct dentry *open_xa_dir(const struct inode *inode, int flags) 138{ 139 struct dentry *xaroot, *xadir; 140 char namebuf[17]; 141 142 xaroot = open_xa_root(inode->i_sb, flags); 143 if (IS_ERR(xaroot)) 144 return xaroot; 145 146 snprintf(namebuf, sizeof(namebuf), "%X.%X", 147 le32_to_cpu(INODE_PKEY(inode)->k_objectid), 148 inode->i_generation); 149 150 mutex_lock_nested(&xaroot->d_inode->i_mutex, I_MUTEX_XATTR); 151 152 xadir = lookup_one_len(namebuf, xaroot, strlen(namebuf)); 153 if (!IS_ERR(xadir) && !xadir->d_inode) { 154 int err = -ENODATA; 155 if (xattr_may_create(flags)) 156 err = xattr_mkdir(xaroot->d_inode, xadir, 0700); 157 if (err) { 158 dput(xadir); 159 xadir = ERR_PTR(err); 160 } 161 } 162 163 mutex_unlock(&xaroot->d_inode->i_mutex); 164 dput(xaroot); 165 return xadir; 166} 167 168/* The following are side effects of other operations that aren't explicitly 169 * modifying extended attributes. This includes operations such as permissions 170 * or ownership changes, object deletions, etc. */ 171struct reiserfs_dentry_buf { 172 struct dir_context ctx; 173 struct dentry *xadir; 174 int count; 175 struct dentry *dentries[8]; 176}; 177 178static int 179fill_with_dentries(void *buf, const char *name, int namelen, loff_t offset, 180 u64 ino, unsigned int d_type) 181{ 182 struct reiserfs_dentry_buf *dbuf = buf; 183 struct dentry *dentry; 184 WARN_ON_ONCE(!mutex_is_locked(&dbuf->xadir->d_inode->i_mutex)); 185 186 if (dbuf->count == ARRAY_SIZE(dbuf->dentries)) 187 return -ENOSPC; 188 189 if (name[0] == '.' && (namelen < 2 || 190 (namelen == 2 && name[1] == '.'))) 191 return 0; 192 193 dentry = lookup_one_len(name, dbuf->xadir, namelen); 194 if (IS_ERR(dentry)) { 195 return PTR_ERR(dentry); 196 } else if (!dentry->d_inode) { 197 /* A directory entry exists, but no file? */ 198 reiserfs_error(dentry->d_sb, "xattr-20003", 199 "Corrupted directory: xattr %s listed but " 200 "not found for file %s.\n", 201 dentry->d_name.name, dbuf->xadir->d_name.name); 202 dput(dentry); 203 return -EIO; 204 } 205 206 dbuf->dentries[dbuf->count++] = dentry; 207 return 0; 208} 209 210static void 211cleanup_dentry_buf(struct reiserfs_dentry_buf *buf) 212{ 213 int i; 214 for (i = 0; i < buf->count; i++) 215 if (buf->dentries[i]) 216 dput(buf->dentries[i]); 217} 218 219static int reiserfs_for_each_xattr(struct inode *inode, 220 int (*action)(struct dentry *, void *), 221 void *data) 222{ 223 struct dentry *dir; 224 int i, err = 0; 225 struct reiserfs_dentry_buf buf = { 226 .ctx.actor = fill_with_dentries, 227 }; 228 229 /* Skip out, an xattr has no xattrs associated with it */ 230 if (IS_PRIVATE(inode) || get_inode_sd_version(inode) == STAT_DATA_V1) 231 return 0; 232 233 dir = open_xa_dir(inode, XATTR_REPLACE); 234 if (IS_ERR(dir)) { 235 err = PTR_ERR(dir); 236 goto out; 237 } else if (!dir->d_inode) { 238 err = 0; 239 goto out_dir; 240 } 241 242 mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR); 243 244 buf.xadir = dir; 245 while (1) { 246 err = reiserfs_readdir_inode(dir->d_inode, &buf.ctx); 247 if (err) 248 break; 249 if (!buf.count) 250 break; 251 for (i = 0; !err && i < buf.count && buf.dentries[i]; i++) { 252 struct dentry *dentry = buf.dentries[i]; 253 254 if (!S_ISDIR(dentry->d_inode->i_mode)) 255 err = action(dentry, data); 256 257 dput(dentry); 258 buf.dentries[i] = NULL; 259 } 260 if (err) 261 break; 262 buf.count = 0; 263 } 264 mutex_unlock(&dir->d_inode->i_mutex); 265 266 cleanup_dentry_buf(&buf); 267 268 if (!err) { 269 /* We start a transaction here to avoid a ABBA situation 270 * between the xattr root's i_mutex and the journal lock. 271 * This doesn't incur much additional overhead since the 272 * new transaction will just nest inside the 273 * outer transaction. */ 274 int blocks = JOURNAL_PER_BALANCE_CNT * 2 + 2 + 275 4 * REISERFS_QUOTA_TRANS_BLOCKS(inode->i_sb); 276 struct reiserfs_transaction_handle th; 277 reiserfs_write_lock(inode->i_sb); 278 err = journal_begin(&th, inode->i_sb, blocks); 279 reiserfs_write_unlock(inode->i_sb); 280 if (!err) { 281 int jerror; 282 mutex_lock_nested(&dir->d_parent->d_inode->i_mutex, 283 I_MUTEX_XATTR); 284 err = action(dir, data); 285 reiserfs_write_lock(inode->i_sb); 286 jerror = journal_end(&th, inode->i_sb, blocks); 287 reiserfs_write_unlock(inode->i_sb); 288 mutex_unlock(&dir->d_parent->d_inode->i_mutex); 289 err = jerror ?: err; 290 } 291 } 292out_dir: 293 dput(dir); 294out: 295 /* -ENODATA isn't an error */ 296 if (err == -ENODATA) 297 err = 0; 298 return err; 299} 300 301static int delete_one_xattr(struct dentry *dentry, void *data) 302{ 303 struct inode *dir = dentry->d_parent->d_inode; 304 305 /* This is the xattr dir, handle specially. */ 306 if (S_ISDIR(dentry->d_inode->i_mode)) 307 return xattr_rmdir(dir, dentry); 308 309 return xattr_unlink(dir, dentry); 310} 311 312static int chown_one_xattr(struct dentry *dentry, void *data) 313{ 314 struct iattr *attrs = data; 315 int ia_valid = attrs->ia_valid; 316 int err; 317 318 /* 319 * We only want the ownership bits. Otherwise, we'll do 320 * things like change a directory to a regular file if 321 * ATTR_MODE is set. 322 */ 323 attrs->ia_valid &= (ATTR_UID|ATTR_GID); 324 err = reiserfs_setattr(dentry, attrs); 325 attrs->ia_valid = ia_valid; 326 327 return err; 328} 329 330/* No i_mutex, but the inode is unconnected. */ 331int reiserfs_delete_xattrs(struct inode *inode) 332{ 333 int err = reiserfs_for_each_xattr(inode, delete_one_xattr, NULL); 334 if (err) 335 reiserfs_warning(inode->i_sb, "jdm-20004", 336 "Couldn't delete all xattrs (%d)\n", err); 337 return err; 338} 339 340/* inode->i_mutex: down */ 341int reiserfs_chown_xattrs(struct inode *inode, struct iattr *attrs) 342{ 343 int err = reiserfs_for_each_xattr(inode, chown_one_xattr, attrs); 344 if (err) 345 reiserfs_warning(inode->i_sb, "jdm-20007", 346 "Couldn't chown all xattrs (%d)\n", err); 347 return err; 348} 349 350#ifdef CONFIG_REISERFS_FS_XATTR 351/* Returns a dentry corresponding to a specific extended attribute file 352 * for the inode. If flags allow, the file is created. Otherwise, a 353 * valid or negative dentry, or an error is returned. */ 354static struct dentry *xattr_lookup(struct inode *inode, const char *name, 355 int flags) 356{ 357 struct dentry *xadir, *xafile; 358 int err = 0; 359 360 xadir = open_xa_dir(inode, flags); 361 if (IS_ERR(xadir)) 362 return ERR_CAST(xadir); 363 364 mutex_lock_nested(&xadir->d_inode->i_mutex, I_MUTEX_XATTR); 365 xafile = lookup_one_len(name, xadir, strlen(name)); 366 if (IS_ERR(xafile)) { 367 err = PTR_ERR(xafile); 368 goto out; 369 } 370 371 if (xafile->d_inode && (flags & XATTR_CREATE)) 372 err = -EEXIST; 373 374 if (!xafile->d_inode) { 375 err = -ENODATA; 376 if (xattr_may_create(flags)) 377 err = xattr_create(xadir->d_inode, xafile, 378 0700|S_IFREG); 379 } 380 381 if (err) 382 dput(xafile); 383out: 384 mutex_unlock(&xadir->d_inode->i_mutex); 385 dput(xadir); 386 if (err) 387 return ERR_PTR(err); 388 return xafile; 389} 390 391/* Internal operations on file data */ 392static inline void reiserfs_put_page(struct page *page) 393{ 394 kunmap(page); 395 page_cache_release(page); 396} 397 398static struct page *reiserfs_get_page(struct inode *dir, size_t n) 399{ 400 struct address_space *mapping = dir->i_mapping; 401 struct page *page; 402 /* We can deadlock if we try to free dentries, 403 and an unlink/rmdir has just occurred - GFP_NOFS avoids this */ 404 mapping_set_gfp_mask(mapping, GFP_NOFS); 405 page = read_mapping_page(mapping, n >> PAGE_CACHE_SHIFT, NULL); 406 if (!IS_ERR(page)) { 407 kmap(page); 408 if (PageError(page)) 409 goto fail; 410 } 411 return page; 412 413 fail: 414 reiserfs_put_page(page); 415 return ERR_PTR(-EIO); 416} 417 418static inline __u32 xattr_hash(const char *msg, int len) 419{ 420 return csum_partial(msg, len, 0); 421} 422 423int reiserfs_commit_write(struct file *f, struct page *page, 424 unsigned from, unsigned to); 425 426static void update_ctime(struct inode *inode) 427{ 428 struct timespec now = current_fs_time(inode->i_sb); 429 if (inode_unhashed(inode) || !inode->i_nlink || 430 timespec_equal(&inode->i_ctime, &now)) 431 return; 432 433 inode->i_ctime = CURRENT_TIME_SEC; 434 mark_inode_dirty(inode); 435} 436 437static int lookup_and_delete_xattr(struct inode *inode, const char *name) 438{ 439 int err = 0; 440 struct dentry *dentry, *xadir; 441 442 xadir = open_xa_dir(inode, XATTR_REPLACE); 443 if (IS_ERR(xadir)) 444 return PTR_ERR(xadir); 445 446 mutex_lock_nested(&xadir->d_inode->i_mutex, I_MUTEX_XATTR); 447 dentry = lookup_one_len(name, xadir, strlen(name)); 448 if (IS_ERR(dentry)) { 449 err = PTR_ERR(dentry); 450 goto out_dput; 451 } 452 453 if (dentry->d_inode) { 454 err = xattr_unlink(xadir->d_inode, dentry); 455 update_ctime(inode); 456 } 457 458 dput(dentry); 459out_dput: 460 mutex_unlock(&xadir->d_inode->i_mutex); 461 dput(xadir); 462 return err; 463} 464 465 466/* Generic extended attribute operations that can be used by xa plugins */ 467 468/* 469 * inode->i_mutex: down 470 */ 471int 472reiserfs_xattr_set_handle(struct reiserfs_transaction_handle *th, 473 struct inode *inode, const char *name, 474 const void *buffer, size_t buffer_size, int flags) 475{ 476 int err = 0; 477 struct dentry *dentry; 478 struct page *page; 479 char *data; 480 size_t file_pos = 0; 481 size_t buffer_pos = 0; 482 size_t new_size; 483 __u32 xahash = 0; 484 485 if (get_inode_sd_version(inode) == STAT_DATA_V1) 486 return -EOPNOTSUPP; 487 488 if (!buffer) { 489 err = lookup_and_delete_xattr(inode, name); 490 return err; 491 } 492 493 dentry = xattr_lookup(inode, name, flags); 494 if (IS_ERR(dentry)) 495 return PTR_ERR(dentry); 496 497 down_write(&REISERFS_I(inode)->i_xattr_sem); 498 499 xahash = xattr_hash(buffer, buffer_size); 500 while (buffer_pos < buffer_size || buffer_pos == 0) { 501 size_t chunk; 502 size_t skip = 0; 503 size_t page_offset = (file_pos & (PAGE_CACHE_SIZE - 1)); 504 if (buffer_size - buffer_pos > PAGE_CACHE_SIZE) 505 chunk = PAGE_CACHE_SIZE; 506 else 507 chunk = buffer_size - buffer_pos; 508 509 page = reiserfs_get_page(dentry->d_inode, file_pos); 510 if (IS_ERR(page)) { 511 err = PTR_ERR(page); 512 goto out_unlock; 513 } 514 515 lock_page(page); 516 data = page_address(page); 517 518 if (file_pos == 0) { 519 struct reiserfs_xattr_header *rxh; 520 skip = file_pos = sizeof(struct reiserfs_xattr_header); 521 if (chunk + skip > PAGE_CACHE_SIZE) 522 chunk = PAGE_CACHE_SIZE - skip; 523 rxh = (struct reiserfs_xattr_header *)data; 524 rxh->h_magic = cpu_to_le32(REISERFS_XATTR_MAGIC); 525 rxh->h_hash = cpu_to_le32(xahash); 526 } 527 528 reiserfs_write_lock(inode->i_sb); 529 err = __reiserfs_write_begin(page, page_offset, chunk + skip); 530 if (!err) { 531 if (buffer) 532 memcpy(data + skip, buffer + buffer_pos, chunk); 533 err = reiserfs_commit_write(NULL, page, page_offset, 534 page_offset + chunk + 535 skip); 536 } 537 reiserfs_write_unlock(inode->i_sb); 538 unlock_page(page); 539 reiserfs_put_page(page); 540 buffer_pos += chunk; 541 file_pos += chunk; 542 skip = 0; 543 if (err || buffer_size == 0 || !buffer) 544 break; 545 } 546 547 new_size = buffer_size + sizeof(struct reiserfs_xattr_header); 548 if (!err && new_size < i_size_read(dentry->d_inode)) { 549 struct iattr newattrs = { 550 .ia_ctime = current_fs_time(inode->i_sb), 551 .ia_size = new_size, 552 .ia_valid = ATTR_SIZE | ATTR_CTIME, 553 }; 554 555 mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_XATTR); 556 inode_dio_wait(dentry->d_inode); 557 558 err = reiserfs_setattr(dentry, &newattrs); 559 mutex_unlock(&dentry->d_inode->i_mutex); 560 } else 561 update_ctime(inode); 562out_unlock: 563 up_write(&REISERFS_I(inode)->i_xattr_sem); 564 dput(dentry); 565 return err; 566} 567 568/* We need to start a transaction to maintain lock ordering */ 569int reiserfs_xattr_set(struct inode *inode, const char *name, 570 const void *buffer, size_t buffer_size, int flags) 571{ 572 573 struct reiserfs_transaction_handle th; 574 int error, error2; 575 size_t jbegin_count = reiserfs_xattr_nblocks(inode, buffer_size); 576 577 if (!(flags & XATTR_REPLACE)) 578 jbegin_count += reiserfs_xattr_jcreate_nblocks(inode); 579 580 reiserfs_write_lock(inode->i_sb); 581 error = journal_begin(&th, inode->i_sb, jbegin_count); 582 reiserfs_write_unlock(inode->i_sb); 583 if (error) { 584 return error; 585 } 586 587 error = reiserfs_xattr_set_handle(&th, inode, name, 588 buffer, buffer_size, flags); 589 590 reiserfs_write_lock(inode->i_sb); 591 error2 = journal_end(&th, inode->i_sb, jbegin_count); 592 reiserfs_write_unlock(inode->i_sb); 593 if (error == 0) 594 error = error2; 595 596 return error; 597} 598 599/* 600 * inode->i_mutex: down 601 */ 602int 603reiserfs_xattr_get(struct inode *inode, const char *name, void *buffer, 604 size_t buffer_size) 605{ 606 ssize_t err = 0; 607 struct dentry *dentry; 608 size_t isize; 609 size_t file_pos = 0; 610 size_t buffer_pos = 0; 611 struct page *page; 612 __u32 hash = 0; 613 614 if (name == NULL) 615 return -EINVAL; 616 617 /* We can't have xattrs attached to v1 items since they don't have 618 * generation numbers */ 619 if (get_inode_sd_version(inode) == STAT_DATA_V1) 620 return -EOPNOTSUPP; 621 622 dentry = xattr_lookup(inode, name, XATTR_REPLACE); 623 if (IS_ERR(dentry)) { 624 err = PTR_ERR(dentry); 625 goto out; 626 } 627 628 down_read(&REISERFS_I(inode)->i_xattr_sem); 629 630 isize = i_size_read(dentry->d_inode); 631 632 /* Just return the size needed */ 633 if (buffer == NULL) { 634 err = isize - sizeof(struct reiserfs_xattr_header); 635 goto out_unlock; 636 } 637 638 if (buffer_size < isize - sizeof(struct reiserfs_xattr_header)) { 639 err = -ERANGE; 640 goto out_unlock; 641 } 642 643 while (file_pos < isize) { 644 size_t chunk; 645 char *data; 646 size_t skip = 0; 647 if (isize - file_pos > PAGE_CACHE_SIZE) 648 chunk = PAGE_CACHE_SIZE; 649 else 650 chunk = isize - file_pos; 651 652 page = reiserfs_get_page(dentry->d_inode, file_pos); 653 if (IS_ERR(page)) { 654 err = PTR_ERR(page); 655 goto out_unlock; 656 } 657 658 lock_page(page); 659 data = page_address(page); 660 if (file_pos == 0) { 661 struct reiserfs_xattr_header *rxh = 662 (struct reiserfs_xattr_header *)data; 663 skip = file_pos = sizeof(struct reiserfs_xattr_header); 664 chunk -= skip; 665 /* Magic doesn't match up.. */ 666 if (rxh->h_magic != cpu_to_le32(REISERFS_XATTR_MAGIC)) { 667 unlock_page(page); 668 reiserfs_put_page(page); 669 reiserfs_warning(inode->i_sb, "jdm-20001", 670 "Invalid magic for xattr (%s) " 671 "associated with %k", name, 672 INODE_PKEY(inode)); 673 err = -EIO; 674 goto out_unlock; 675 } 676 hash = le32_to_cpu(rxh->h_hash); 677 } 678 memcpy(buffer + buffer_pos, data + skip, chunk); 679 unlock_page(page); 680 reiserfs_put_page(page); 681 file_pos += chunk; 682 buffer_pos += chunk; 683 skip = 0; 684 } 685 err = isize - sizeof(struct reiserfs_xattr_header); 686 687 if (xattr_hash(buffer, isize - sizeof(struct reiserfs_xattr_header)) != 688 hash) { 689 reiserfs_warning(inode->i_sb, "jdm-20002", 690 "Invalid hash for xattr (%s) associated " 691 "with %k", name, INODE_PKEY(inode)); 692 err = -EIO; 693 } 694 695out_unlock: 696 up_read(&REISERFS_I(inode)->i_xattr_sem); 697 dput(dentry); 698 699out: 700 return err; 701} 702 703/* 704 * In order to implement different sets of xattr operations for each xattr 705 * prefix with the generic xattr API, a filesystem should create a 706 * null-terminated array of struct xattr_handler (one for each prefix) and 707 * hang a pointer to it off of the s_xattr field of the superblock. 708 * 709 * The generic_fooxattr() functions will use this list to dispatch xattr 710 * operations to the correct xattr_handler. 711 */ 712#define for_each_xattr_handler(handlers, handler) \ 713 for ((handler) = *(handlers)++; \ 714 (handler) != NULL; \ 715 (handler) = *(handlers)++) 716 717/* This is the implementation for the xattr plugin infrastructure */ 718static inline const struct xattr_handler * 719find_xattr_handler_prefix(const struct xattr_handler **handlers, 720 const char *name) 721{ 722 const struct xattr_handler *xah; 723 724 if (!handlers) 725 return NULL; 726 727 for_each_xattr_handler(handlers, xah) { 728 if (strncmp(xah->prefix, name, strlen(xah->prefix)) == 0) 729 break; 730 } 731 732 return xah; 733} 734 735 736/* 737 * Inode operation getxattr() 738 */ 739ssize_t 740reiserfs_getxattr(struct dentry * dentry, const char *name, void *buffer, 741 size_t size) 742{ 743 const struct xattr_handler *handler; 744 745 handler = find_xattr_handler_prefix(dentry->d_sb->s_xattr, name); 746 747 if (!handler || get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1) 748 return -EOPNOTSUPP; 749 750 return handler->get(dentry, name, buffer, size, handler->flags); 751} 752 753/* 754 * Inode operation setxattr() 755 * 756 * dentry->d_inode->i_mutex down 757 */ 758int 759reiserfs_setxattr(struct dentry *dentry, const char *name, const void *value, 760 size_t size, int flags) 761{ 762 const struct xattr_handler *handler; 763 764 handler = find_xattr_handler_prefix(dentry->d_sb->s_xattr, name); 765 766 if (!handler || get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1) 767 return -EOPNOTSUPP; 768 769 return handler->set(dentry, name, value, size, flags, handler->flags); 770} 771 772/* 773 * Inode operation removexattr() 774 * 775 * dentry->d_inode->i_mutex down 776 */ 777int reiserfs_removexattr(struct dentry *dentry, const char *name) 778{ 779 const struct xattr_handler *handler; 780 handler = find_xattr_handler_prefix(dentry->d_sb->s_xattr, name); 781 782 if (!handler || get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1) 783 return -EOPNOTSUPP; 784 785 return handler->set(dentry, name, NULL, 0, XATTR_REPLACE, handler->flags); 786} 787 788struct listxattr_buf { 789 struct dir_context ctx; 790 size_t size; 791 size_t pos; 792 char *buf; 793 struct dentry *dentry; 794}; 795 796static int listxattr_filler(void *buf, const char *name, int namelen, 797 loff_t offset, u64 ino, unsigned int d_type) 798{ 799 struct listxattr_buf *b = (struct listxattr_buf *)buf; 800 size_t size; 801 if (name[0] != '.' || 802 (namelen != 1 && (name[1] != '.' || namelen != 2))) { 803 const struct xattr_handler *handler; 804 handler = find_xattr_handler_prefix(b->dentry->d_sb->s_xattr, 805 name); 806 if (!handler) /* Unsupported xattr name */ 807 return 0; 808 if (b->buf) { 809 size = handler->list(b->dentry, b->buf + b->pos, 810 b->size, name, namelen, 811 handler->flags); 812 if (size > b->size) 813 return -ERANGE; 814 } else { 815 size = handler->list(b->dentry, NULL, 0, name, 816 namelen, handler->flags); 817 } 818 819 b->pos += size; 820 } 821 return 0; 822} 823 824/* 825 * Inode operation listxattr() 826 * 827 * We totally ignore the generic listxattr here because it would be stupid 828 * not to. Since the xattrs are organized in a directory, we can just 829 * readdir to find them. 830 */ 831ssize_t reiserfs_listxattr(struct dentry * dentry, char *buffer, size_t size) 832{ 833 struct dentry *dir; 834 int err = 0; 835 struct listxattr_buf buf = { 836 .ctx.actor = listxattr_filler, 837 .dentry = dentry, 838 .buf = buffer, 839 .size = buffer ? size : 0, 840 }; 841 842 if (!dentry->d_inode) 843 return -EINVAL; 844 845 if (!dentry->d_sb->s_xattr || 846 get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1) 847 return -EOPNOTSUPP; 848 849 dir = open_xa_dir(dentry->d_inode, XATTR_REPLACE); 850 if (IS_ERR(dir)) { 851 err = PTR_ERR(dir); 852 if (err == -ENODATA) 853 err = 0; /* Not an error if there aren't any xattrs */ 854 goto out; 855 } 856 857 mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR); 858 err = reiserfs_readdir_inode(dir->d_inode, &buf.ctx); 859 mutex_unlock(&dir->d_inode->i_mutex); 860 861 if (!err) 862 err = buf.pos; 863 864 dput(dir); 865out: 866 return err; 867} 868 869static int create_privroot(struct dentry *dentry) 870{ 871 int err; 872 struct inode *inode = dentry->d_parent->d_inode; 873 WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex)); 874 875 err = xattr_mkdir(inode, dentry, 0700); 876 if (err || !dentry->d_inode) { 877 reiserfs_warning(dentry->d_sb, "jdm-20006", 878 "xattrs/ACLs enabled and couldn't " 879 "find/create .reiserfs_priv. " 880 "Failing mount."); 881 return -EOPNOTSUPP; 882 } 883 884 dentry->d_inode->i_flags |= S_PRIVATE; 885 reiserfs_info(dentry->d_sb, "Created %s - reserved for xattr " 886 "storage.\n", PRIVROOT_NAME); 887 888 return 0; 889} 890 891#else 892int __init reiserfs_xattr_register_handlers(void) { return 0; } 893void reiserfs_xattr_unregister_handlers(void) {} 894static int create_privroot(struct dentry *dentry) { return 0; } 895#endif 896 897/* Actual operations that are exported to VFS-land */ 898static const struct xattr_handler *reiserfs_xattr_handlers[] = { 899#ifdef CONFIG_REISERFS_FS_XATTR 900 &reiserfs_xattr_user_handler, 901 &reiserfs_xattr_trusted_handler, 902#endif 903#ifdef CONFIG_REISERFS_FS_SECURITY 904 &reiserfs_xattr_security_handler, 905#endif 906#ifdef CONFIG_REISERFS_FS_POSIX_ACL 907 &reiserfs_posix_acl_access_handler, 908 &reiserfs_posix_acl_default_handler, 909#endif 910 NULL 911}; 912 913static int xattr_mount_check(struct super_block *s) 914{ 915 /* We need generation numbers to ensure that the oid mapping is correct 916 * v3.5 filesystems don't have them. */ 917 if (old_format_only(s)) { 918 if (reiserfs_xattrs_optional(s)) { 919 /* Old format filesystem, but optional xattrs have 920 * been enabled. Error out. */ 921 reiserfs_warning(s, "jdm-2005", 922 "xattrs/ACLs not supported " 923 "on pre-v3.6 format filesystems. " 924 "Failing mount."); 925 return -EOPNOTSUPP; 926 } 927 } 928 929 return 0; 930} 931 932int reiserfs_permission(struct inode *inode, int mask) 933{ 934 /* 935 * We don't do permission checks on the internal objects. 936 * Permissions are determined by the "owning" object. 937 */ 938 if (IS_PRIVATE(inode)) 939 return 0; 940 941 return generic_permission(inode, mask); 942} 943 944static int xattr_hide_revalidate(struct dentry *dentry, unsigned int flags) 945{ 946 return -EPERM; 947} 948 949static const struct dentry_operations xattr_lookup_poison_ops = { 950 .d_revalidate = xattr_hide_revalidate, 951}; 952 953int reiserfs_lookup_privroot(struct super_block *s) 954{ 955 struct dentry *dentry; 956 int err = 0; 957 958 /* If we don't have the privroot located yet - go find it */ 959 mutex_lock(&s->s_root->d_inode->i_mutex); 960 dentry = lookup_one_len(PRIVROOT_NAME, s->s_root, 961 strlen(PRIVROOT_NAME)); 962 if (!IS_ERR(dentry)) { 963 REISERFS_SB(s)->priv_root = dentry; 964 d_set_d_op(dentry, &xattr_lookup_poison_ops); 965 if (dentry->d_inode) 966 dentry->d_inode->i_flags |= S_PRIVATE; 967 } else 968 err = PTR_ERR(dentry); 969 mutex_unlock(&s->s_root->d_inode->i_mutex); 970 971 return err; 972} 973 974/* We need to take a copy of the mount flags since things like 975 * MS_RDONLY don't get set until *after* we're called. 976 * mount_flags != mount_options */ 977int reiserfs_xattr_init(struct super_block *s, int mount_flags) 978{ 979 int err = 0; 980 struct dentry *privroot = REISERFS_SB(s)->priv_root; 981 982 err = xattr_mount_check(s); 983 if (err) 984 goto error; 985 986 if (!privroot->d_inode && !(mount_flags & MS_RDONLY)) { 987 mutex_lock(&s->s_root->d_inode->i_mutex); 988 err = create_privroot(REISERFS_SB(s)->priv_root); 989 mutex_unlock(&s->s_root->d_inode->i_mutex); 990 } 991 992 if (privroot->d_inode) { 993 s->s_xattr = reiserfs_xattr_handlers; 994 mutex_lock(&privroot->d_inode->i_mutex); 995 if (!REISERFS_SB(s)->xattr_root) { 996 struct dentry *dentry; 997 dentry = lookup_one_len(XAROOT_NAME, privroot, 998 strlen(XAROOT_NAME)); 999 if (!IS_ERR(dentry)) 1000 REISERFS_SB(s)->xattr_root = dentry; 1001 else 1002 err = PTR_ERR(dentry); 1003 } 1004 mutex_unlock(&privroot->d_inode->i_mutex); 1005 } 1006 1007error: 1008 if (err) { 1009 clear_bit(REISERFS_XATTRS_USER, &(REISERFS_SB(s)->s_mount_opt)); 1010 clear_bit(REISERFS_POSIXACL, &(REISERFS_SB(s)->s_mount_opt)); 1011 } 1012 1013 /* The super_block MS_POSIXACL must mirror the (no)acl mount option. */ 1014 if (reiserfs_posixacl(s)) 1015 s->s_flags |= MS_POSIXACL; 1016 else 1017 s->s_flags &= ~MS_POSIXACL; 1018 1019 return err; 1020} 1021