linux/fs/reiserfs/xattr.c
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   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        reiserfs_mutex_lock_nested_safe(&dentry->d_inode->i_mutex,
  85                                        I_MUTEX_CHILD, dir->i_sb);
  86        error = dir->i_op->unlink(dir, dentry);
  87        mutex_unlock(&dentry->d_inode->i_mutex);
  88
  89        if (!error)
  90                d_delete(dentry);
  91        return error;
  92}
  93
  94static int xattr_rmdir(struct inode *dir, struct dentry *dentry)
  95{
  96        int error;
  97        BUG_ON(!mutex_is_locked(&dir->i_mutex));
  98
  99        reiserfs_mutex_lock_nested_safe(&dentry->d_inode->i_mutex,
 100                                        I_MUTEX_CHILD, dir->i_sb);
 101        error = dir->i_op->rmdir(dir, dentry);
 102        if (!error)
 103                dentry->d_inode->i_flags |= S_DEAD;
 104        mutex_unlock(&dentry->d_inode->i_mutex);
 105        if (!error)
 106                d_delete(dentry);
 107
 108        return error;
 109}
 110
 111#define xattr_may_create(flags) (!flags || flags & XATTR_CREATE)
 112
 113static struct dentry *open_xa_root(struct super_block *sb, int flags)
 114{
 115        struct dentry *privroot = REISERFS_SB(sb)->priv_root;
 116        struct dentry *xaroot;
 117        if (!privroot->d_inode)
 118                return ERR_PTR(-ENODATA);
 119
 120        mutex_lock_nested(&privroot->d_inode->i_mutex, I_MUTEX_XATTR);
 121
 122        xaroot = dget(REISERFS_SB(sb)->xattr_root);
 123        if (!xaroot)
 124                xaroot = ERR_PTR(-ENODATA);
 125        else if (!xaroot->d_inode) {
 126                int err = -ENODATA;
 127                if (xattr_may_create(flags))
 128                        err = xattr_mkdir(privroot->d_inode, xaroot, 0700);
 129                if (err) {
 130                        dput(xaroot);
 131                        xaroot = ERR_PTR(err);
 132                }
 133        }
 134
 135        mutex_unlock(&privroot->d_inode->i_mutex);
 136        return xaroot;
 137}
 138
 139static struct dentry *open_xa_dir(const struct inode *inode, int flags)
 140{
 141        struct dentry *xaroot, *xadir;
 142        char namebuf[17];
 143
 144        xaroot = open_xa_root(inode->i_sb, flags);
 145        if (IS_ERR(xaroot))
 146                return xaroot;
 147
 148        snprintf(namebuf, sizeof(namebuf), "%X.%X",
 149                 le32_to_cpu(INODE_PKEY(inode)->k_objectid),
 150                 inode->i_generation);
 151
 152        mutex_lock_nested(&xaroot->d_inode->i_mutex, I_MUTEX_XATTR);
 153
 154        xadir = lookup_one_len(namebuf, xaroot, strlen(namebuf));
 155        if (!IS_ERR(xadir) && !xadir->d_inode) {
 156                int err = -ENODATA;
 157                if (xattr_may_create(flags))
 158                        err = xattr_mkdir(xaroot->d_inode, xadir, 0700);
 159                if (err) {
 160                        dput(xadir);
 161                        xadir = ERR_PTR(err);
 162                }
 163        }
 164
 165        mutex_unlock(&xaroot->d_inode->i_mutex);
 166        dput(xaroot);
 167        return xadir;
 168}
 169
 170/* The following are side effects of other operations that aren't explicitly
 171 * modifying extended attributes. This includes operations such as permissions
 172 * or ownership changes, object deletions, etc. */
 173struct reiserfs_dentry_buf {
 174        struct dentry *xadir;
 175        int count;
 176        struct dentry *dentries[8];
 177};
 178
 179static int
 180fill_with_dentries(void *buf, const char *name, int namelen, loff_t offset,
 181                    u64 ino, unsigned int d_type)
 182{
 183        struct reiserfs_dentry_buf *dbuf = buf;
 184        struct dentry *dentry;
 185        WARN_ON_ONCE(!mutex_is_locked(&dbuf->xadir->d_inode->i_mutex));
 186
 187        if (dbuf->count == ARRAY_SIZE(dbuf->dentries))
 188                return -ENOSPC;
 189
 190        if (name[0] == '.' && (name[1] == '\0' ||
 191                               (name[1] == '.' && name[2] == '\0')))
 192                return 0;
 193
 194        dentry = lookup_one_len(name, dbuf->xadir, namelen);
 195        if (IS_ERR(dentry)) {
 196                return PTR_ERR(dentry);
 197        } else if (!dentry->d_inode) {
 198                /* A directory entry exists, but no file? */
 199                reiserfs_error(dentry->d_sb, "xattr-20003",
 200                               "Corrupted directory: xattr %s listed but "
 201                               "not found for file %s.\n",
 202                               dentry->d_name.name, dbuf->xadir->d_name.name);
 203                dput(dentry);
 204                return -EIO;
 205        }
 206
 207        dbuf->dentries[dbuf->count++] = dentry;
 208        return 0;
 209}
 210
 211static void
 212cleanup_dentry_buf(struct reiserfs_dentry_buf *buf)
 213{
 214        int i;
 215        for (i = 0; i < buf->count; i++)
 216                if (buf->dentries[i])
 217                        dput(buf->dentries[i]);
 218}
 219
 220static int reiserfs_for_each_xattr(struct inode *inode,
 221                                   int (*action)(struct dentry *, void *),
 222                                   void *data)
 223{
 224        struct dentry *dir;
 225        int i, err = 0;
 226        loff_t pos = 0;
 227        struct reiserfs_dentry_buf buf = {
 228                .count = 0,
 229        };
 230
 231        /* Skip out, an xattr has no xattrs associated with it */
 232        if (IS_PRIVATE(inode) || get_inode_sd_version(inode) == STAT_DATA_V1)
 233                return 0;
 234
 235        reiserfs_write_unlock(inode->i_sb);
 236        dir = open_xa_dir(inode, XATTR_REPLACE);
 237        if (IS_ERR(dir)) {
 238                err = PTR_ERR(dir);
 239                reiserfs_write_lock(inode->i_sb);
 240                goto out;
 241        } else if (!dir->d_inode) {
 242                err = 0;
 243                reiserfs_write_lock(inode->i_sb);
 244                goto out_dir;
 245        }
 246
 247        mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR);
 248
 249        reiserfs_write_lock(inode->i_sb);
 250
 251        buf.xadir = dir;
 252        err = reiserfs_readdir_dentry(dir, &buf, fill_with_dentries, &pos);
 253        while ((err == 0 || err == -ENOSPC) && buf.count) {
 254                err = 0;
 255
 256                for (i = 0; i < buf.count && buf.dentries[i]; i++) {
 257                        int lerr = 0;
 258                        struct dentry *dentry = buf.dentries[i];
 259
 260                        if (err == 0 && !S_ISDIR(dentry->d_inode->i_mode))
 261                                lerr = action(dentry, data);
 262
 263                        dput(dentry);
 264                        buf.dentries[i] = NULL;
 265                        err = lerr ?: err;
 266                }
 267                buf.count = 0;
 268                if (!err)
 269                        err = reiserfs_readdir_dentry(dir, &buf,
 270                                                      fill_with_dentries, &pos);
 271        }
 272        mutex_unlock(&dir->d_inode->i_mutex);
 273
 274        /* Clean up after a failed readdir */
 275        cleanup_dentry_buf(&buf);
 276
 277        if (!err) {
 278                /* We start a transaction here to avoid a ABBA situation
 279                 * between the xattr root's i_mutex and the journal lock.
 280                 * This doesn't incur much additional overhead since the
 281                 * new transaction will just nest inside the
 282                 * outer transaction. */
 283                int blocks = JOURNAL_PER_BALANCE_CNT * 2 + 2 +
 284                             4 * REISERFS_QUOTA_TRANS_BLOCKS(inode->i_sb);
 285                struct reiserfs_transaction_handle th;
 286                err = journal_begin(&th, inode->i_sb, blocks);
 287                if (!err) {
 288                        int jerror;
 289                        reiserfs_mutex_lock_nested_safe(
 290                                          &dir->d_parent->d_inode->i_mutex,
 291                                          I_MUTEX_XATTR, inode->i_sb);
 292                        err = action(dir, data);
 293                        jerror = journal_end(&th, inode->i_sb, blocks);
 294                        mutex_unlock(&dir->d_parent->d_inode->i_mutex);
 295                        err = jerror ?: err;
 296                }
 297        }
 298out_dir:
 299        dput(dir);
 300out:
 301        /* -ENODATA isn't an error */
 302        if (err == -ENODATA)
 303                err = 0;
 304        return err;
 305}
 306
 307static int delete_one_xattr(struct dentry *dentry, void *data)
 308{
 309        struct inode *dir = dentry->d_parent->d_inode;
 310
 311        /* This is the xattr dir, handle specially. */
 312        if (S_ISDIR(dentry->d_inode->i_mode))
 313                return xattr_rmdir(dir, dentry);
 314
 315        return xattr_unlink(dir, dentry);
 316}
 317
 318static int chown_one_xattr(struct dentry *dentry, void *data)
 319{
 320        struct iattr *attrs = data;
 321        return reiserfs_setattr(dentry, attrs);
 322}
 323
 324/* No i_mutex, but the inode is unconnected. */
 325int reiserfs_delete_xattrs(struct inode *inode)
 326{
 327        int err = reiserfs_for_each_xattr(inode, delete_one_xattr, NULL);
 328        if (err)
 329                reiserfs_warning(inode->i_sb, "jdm-20004",
 330                                 "Couldn't delete all xattrs (%d)\n", err);
 331        return err;
 332}
 333
 334/* inode->i_mutex: down */
 335int reiserfs_chown_xattrs(struct inode *inode, struct iattr *attrs)
 336{
 337        int err = reiserfs_for_each_xattr(inode, chown_one_xattr, attrs);
 338        if (err)
 339                reiserfs_warning(inode->i_sb, "jdm-20007",
 340                                 "Couldn't chown all xattrs (%d)\n", err);
 341        return err;
 342}
 343
 344#ifdef CONFIG_REISERFS_FS_XATTR
 345/* Returns a dentry corresponding to a specific extended attribute file
 346 * for the inode. If flags allow, the file is created. Otherwise, a
 347 * valid or negative dentry, or an error is returned. */
 348static struct dentry *xattr_lookup(struct inode *inode, const char *name,
 349                                    int flags)
 350{
 351        struct dentry *xadir, *xafile;
 352        int err = 0;
 353
 354        xadir = open_xa_dir(inode, flags);
 355        if (IS_ERR(xadir))
 356                return ERR_CAST(xadir);
 357
 358        mutex_lock_nested(&xadir->d_inode->i_mutex, I_MUTEX_XATTR);
 359        xafile = lookup_one_len(name, xadir, strlen(name));
 360        if (IS_ERR(xafile)) {
 361                err = PTR_ERR(xafile);
 362                goto out;
 363        }
 364
 365        if (xafile->d_inode && (flags & XATTR_CREATE))
 366                err = -EEXIST;
 367
 368        if (!xafile->d_inode) {
 369                err = -ENODATA;
 370                if (xattr_may_create(flags))
 371                        err = xattr_create(xadir->d_inode, xafile,
 372                                              0700|S_IFREG);
 373        }
 374
 375        if (err)
 376                dput(xafile);
 377out:
 378        mutex_unlock(&xadir->d_inode->i_mutex);
 379        dput(xadir);
 380        if (err)
 381                return ERR_PTR(err);
 382        return xafile;
 383}
 384
 385/* Internal operations on file data */
 386static inline void reiserfs_put_page(struct page *page)
 387{
 388        kunmap(page);
 389        page_cache_release(page);
 390}
 391
 392static struct page *reiserfs_get_page(struct inode *dir, size_t n)
 393{
 394        struct address_space *mapping = dir->i_mapping;
 395        struct page *page;
 396        /* We can deadlock if we try to free dentries,
 397           and an unlink/rmdir has just occurred - GFP_NOFS avoids this */
 398        mapping_set_gfp_mask(mapping, GFP_NOFS);
 399        page = read_mapping_page(mapping, n >> PAGE_CACHE_SHIFT, NULL);
 400        if (!IS_ERR(page)) {
 401                kmap(page);
 402                if (PageError(page))
 403                        goto fail;
 404        }
 405        return page;
 406
 407      fail:
 408        reiserfs_put_page(page);
 409        return ERR_PTR(-EIO);
 410}
 411
 412static inline __u32 xattr_hash(const char *msg, int len)
 413{
 414        return csum_partial(msg, len, 0);
 415}
 416
 417int reiserfs_commit_write(struct file *f, struct page *page,
 418                          unsigned from, unsigned to);
 419
 420static void update_ctime(struct inode *inode)
 421{
 422        struct timespec now = current_fs_time(inode->i_sb);
 423        if (inode_unhashed(inode) || !inode->i_nlink ||
 424            timespec_equal(&inode->i_ctime, &now))
 425                return;
 426
 427        inode->i_ctime = CURRENT_TIME_SEC;
 428        mark_inode_dirty(inode);
 429}
 430
 431static int lookup_and_delete_xattr(struct inode *inode, const char *name)
 432{
 433        int err = 0;
 434        struct dentry *dentry, *xadir;
 435
 436        xadir = open_xa_dir(inode, XATTR_REPLACE);
 437        if (IS_ERR(xadir))
 438                return PTR_ERR(xadir);
 439
 440        mutex_lock_nested(&xadir->d_inode->i_mutex, I_MUTEX_XATTR);
 441        dentry = lookup_one_len(name, xadir, strlen(name));
 442        if (IS_ERR(dentry)) {
 443                err = PTR_ERR(dentry);
 444                goto out_dput;
 445        }
 446
 447        if (dentry->d_inode) {
 448                reiserfs_write_lock(inode->i_sb);
 449                err = xattr_unlink(xadir->d_inode, dentry);
 450                reiserfs_write_unlock(inode->i_sb);
 451                update_ctime(inode);
 452        }
 453
 454        dput(dentry);
 455out_dput:
 456        mutex_unlock(&xadir->d_inode->i_mutex);
 457        dput(xadir);
 458        return err;
 459}
 460
 461
 462/* Generic extended attribute operations that can be used by xa plugins */
 463
 464/*
 465 * inode->i_mutex: down
 466 */
 467int
 468reiserfs_xattr_set_handle(struct reiserfs_transaction_handle *th,
 469                          struct inode *inode, const char *name,
 470                          const void *buffer, size_t buffer_size, int flags)
 471{
 472        int err = 0;
 473        struct dentry *dentry;
 474        struct page *page;
 475        char *data;
 476        size_t file_pos = 0;
 477        size_t buffer_pos = 0;
 478        size_t new_size;
 479        __u32 xahash = 0;
 480
 481        if (get_inode_sd_version(inode) == STAT_DATA_V1)
 482                return -EOPNOTSUPP;
 483
 484        reiserfs_write_unlock(inode->i_sb);
 485
 486        if (!buffer) {
 487                err = lookup_and_delete_xattr(inode, name);
 488                reiserfs_write_lock(inode->i_sb);
 489                return err;
 490        }
 491
 492        dentry = xattr_lookup(inode, name, flags);
 493        if (IS_ERR(dentry)) {
 494                reiserfs_write_lock(inode->i_sb);
 495                return PTR_ERR(dentry);
 496        }
 497
 498        down_write(&REISERFS_I(inode)->i_xattr_sem);
 499
 500        reiserfs_write_lock(inode->i_sb);
 501
 502        xahash = xattr_hash(buffer, buffer_size);
 503        while (buffer_pos < buffer_size || buffer_pos == 0) {
 504                size_t chunk;
 505                size_t skip = 0;
 506                size_t page_offset = (file_pos & (PAGE_CACHE_SIZE - 1));
 507                if (buffer_size - buffer_pos > PAGE_CACHE_SIZE)
 508                        chunk = PAGE_CACHE_SIZE;
 509                else
 510                        chunk = buffer_size - buffer_pos;
 511
 512                page = reiserfs_get_page(dentry->d_inode, file_pos);
 513                if (IS_ERR(page)) {
 514                        err = PTR_ERR(page);
 515                        goto out_unlock;
 516                }
 517
 518                lock_page(page);
 519                data = page_address(page);
 520
 521                if (file_pos == 0) {
 522                        struct reiserfs_xattr_header *rxh;
 523                        skip = file_pos = sizeof(struct reiserfs_xattr_header);
 524                        if (chunk + skip > PAGE_CACHE_SIZE)
 525                                chunk = PAGE_CACHE_SIZE - skip;
 526                        rxh = (struct reiserfs_xattr_header *)data;
 527                        rxh->h_magic = cpu_to_le32(REISERFS_XATTR_MAGIC);
 528                        rxh->h_hash = cpu_to_le32(xahash);
 529                }
 530
 531                err = __reiserfs_write_begin(page, page_offset, chunk + skip);
 532                if (!err) {
 533                        if (buffer)
 534                                memcpy(data + skip, buffer + buffer_pos, chunk);
 535                        err = reiserfs_commit_write(NULL, page, page_offset,
 536                                                    page_offset + chunk +
 537                                                    skip);
 538                }
 539                unlock_page(page);
 540                reiserfs_put_page(page);
 541                buffer_pos += chunk;
 542                file_pos += chunk;
 543                skip = 0;
 544                if (err || buffer_size == 0 || !buffer)
 545                        break;
 546        }
 547
 548        new_size = buffer_size + sizeof(struct reiserfs_xattr_header);
 549        if (!err && new_size < i_size_read(dentry->d_inode)) {
 550                struct iattr newattrs = {
 551                        .ia_ctime = current_fs_time(inode->i_sb),
 552                        .ia_size = new_size,
 553                        .ia_valid = ATTR_SIZE | ATTR_CTIME,
 554                };
 555
 556                reiserfs_write_unlock(inode->i_sb);
 557                mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_XATTR);
 558                inode_dio_wait(dentry->d_inode);
 559                reiserfs_write_lock(inode->i_sb);
 560
 561                err = reiserfs_setattr(dentry, &newattrs);
 562                mutex_unlock(&dentry->d_inode->i_mutex);
 563        } else
 564                update_ctime(inode);
 565out_unlock:
 566        up_write(&REISERFS_I(inode)->i_xattr_sem);
 567        dput(dentry);
 568        return err;
 569}
 570
 571/* We need to start a transaction to maintain lock ordering */
 572int reiserfs_xattr_set(struct inode *inode, const char *name,
 573                       const void *buffer, size_t buffer_size, int flags)
 574{
 575
 576        struct reiserfs_transaction_handle th;
 577        int error, error2;
 578        size_t jbegin_count = reiserfs_xattr_nblocks(inode, buffer_size);
 579
 580        if (!(flags & XATTR_REPLACE))
 581                jbegin_count += reiserfs_xattr_jcreate_nblocks(inode);
 582
 583        reiserfs_write_lock(inode->i_sb);
 584        error = journal_begin(&th, inode->i_sb, jbegin_count);
 585        if (error) {
 586                reiserfs_write_unlock(inode->i_sb);
 587                return error;
 588        }
 589
 590        error = reiserfs_xattr_set_handle(&th, inode, name,
 591                                          buffer, buffer_size, flags);
 592
 593        error2 = journal_end(&th, inode->i_sb, jbegin_count);
 594        if (error == 0)
 595                error = error2;
 596        reiserfs_write_unlock(inode->i_sb);
 597
 598        return error;
 599}
 600
 601/*
 602 * inode->i_mutex: down
 603 */
 604int
 605reiserfs_xattr_get(struct inode *inode, const char *name, void *buffer,
 606                   size_t buffer_size)
 607{
 608        ssize_t err = 0;
 609        struct dentry *dentry;
 610        size_t isize;
 611        size_t file_pos = 0;
 612        size_t buffer_pos = 0;
 613        struct page *page;
 614        __u32 hash = 0;
 615
 616        if (name == NULL)
 617                return -EINVAL;
 618
 619        /* We can't have xattrs attached to v1 items since they don't have
 620         * generation numbers */
 621        if (get_inode_sd_version(inode) == STAT_DATA_V1)
 622                return -EOPNOTSUPP;
 623
 624        dentry = xattr_lookup(inode, name, XATTR_REPLACE);
 625        if (IS_ERR(dentry)) {
 626                err = PTR_ERR(dentry);
 627                goto out;
 628        }
 629
 630        down_read(&REISERFS_I(inode)->i_xattr_sem);
 631
 632        isize = i_size_read(dentry->d_inode);
 633
 634        /* Just return the size needed */
 635        if (buffer == NULL) {
 636                err = isize - sizeof(struct reiserfs_xattr_header);
 637                goto out_unlock;
 638        }
 639
 640        if (buffer_size < isize - sizeof(struct reiserfs_xattr_header)) {
 641                err = -ERANGE;
 642                goto out_unlock;
 643        }
 644
 645        while (file_pos < isize) {
 646                size_t chunk;
 647                char *data;
 648                size_t skip = 0;
 649                if (isize - file_pos > PAGE_CACHE_SIZE)
 650                        chunk = PAGE_CACHE_SIZE;
 651                else
 652                        chunk = isize - file_pos;
 653
 654                page = reiserfs_get_page(dentry->d_inode, file_pos);
 655                if (IS_ERR(page)) {
 656                        err = PTR_ERR(page);
 657                        goto out_unlock;
 658                }
 659
 660                lock_page(page);
 661                data = page_address(page);
 662                if (file_pos == 0) {
 663                        struct reiserfs_xattr_header *rxh =
 664                            (struct reiserfs_xattr_header *)data;
 665                        skip = file_pos = sizeof(struct reiserfs_xattr_header);
 666                        chunk -= skip;
 667                        /* Magic doesn't match up.. */
 668                        if (rxh->h_magic != cpu_to_le32(REISERFS_XATTR_MAGIC)) {
 669                                unlock_page(page);
 670                                reiserfs_put_page(page);
 671                                reiserfs_warning(inode->i_sb, "jdm-20001",
 672                                                 "Invalid magic for xattr (%s) "
 673                                                 "associated with %k", name,
 674                                                 INODE_PKEY(inode));
 675                                err = -EIO;
 676                                goto out_unlock;
 677                        }
 678                        hash = le32_to_cpu(rxh->h_hash);
 679                }
 680                memcpy(buffer + buffer_pos, data + skip, chunk);
 681                unlock_page(page);
 682                reiserfs_put_page(page);
 683                file_pos += chunk;
 684                buffer_pos += chunk;
 685                skip = 0;
 686        }
 687        err = isize - sizeof(struct reiserfs_xattr_header);
 688
 689        if (xattr_hash(buffer, isize - sizeof(struct reiserfs_xattr_header)) !=
 690            hash) {
 691                reiserfs_warning(inode->i_sb, "jdm-20002",
 692                                 "Invalid hash for xattr (%s) associated "
 693                                 "with %k", name, INODE_PKEY(inode));
 694                err = -EIO;
 695        }
 696
 697out_unlock:
 698        up_read(&REISERFS_I(inode)->i_xattr_sem);
 699        dput(dentry);
 700
 701out:
 702        return err;
 703}
 704
 705/*
 706 * In order to implement different sets of xattr operations for each xattr
 707 * prefix with the generic xattr API, a filesystem should create a
 708 * null-terminated array of struct xattr_handler (one for each prefix) and
 709 * hang a pointer to it off of the s_xattr field of the superblock.
 710 *
 711 * The generic_fooxattr() functions will use this list to dispatch xattr
 712 * operations to the correct xattr_handler.
 713 */
 714#define for_each_xattr_handler(handlers, handler)               \
 715                for ((handler) = *(handlers)++;                 \
 716                        (handler) != NULL;                      \
 717                        (handler) = *(handlers)++)
 718
 719/* This is the implementation for the xattr plugin infrastructure */
 720static inline const struct xattr_handler *
 721find_xattr_handler_prefix(const struct xattr_handler **handlers,
 722                           const char *name)
 723{
 724        const struct xattr_handler *xah;
 725
 726        if (!handlers)
 727                return NULL;
 728
 729        for_each_xattr_handler(handlers, xah) {
 730                if (strncmp(xah->prefix, name, strlen(xah->prefix)) == 0)
 731                        break;
 732        }
 733
 734        return xah;
 735}
 736
 737
 738/*
 739 * Inode operation getxattr()
 740 */
 741ssize_t
 742reiserfs_getxattr(struct dentry * dentry, const char *name, void *buffer,
 743                  size_t size)
 744{
 745        const struct xattr_handler *handler;
 746
 747        handler = find_xattr_handler_prefix(dentry->d_sb->s_xattr, name);
 748
 749        if (!handler || get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
 750                return -EOPNOTSUPP;
 751
 752        return handler->get(dentry, name, buffer, size, handler->flags);
 753}
 754
 755/*
 756 * Inode operation setxattr()
 757 *
 758 * dentry->d_inode->i_mutex down
 759 */
 760int
 761reiserfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 762                  size_t size, int flags)
 763{
 764        const struct xattr_handler *handler;
 765
 766        handler = find_xattr_handler_prefix(dentry->d_sb->s_xattr, name);
 767
 768        if (!handler || get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
 769                return -EOPNOTSUPP;
 770
 771        return handler->set(dentry, name, value, size, flags, handler->flags);
 772}
 773
 774/*
 775 * Inode operation removexattr()
 776 *
 777 * dentry->d_inode->i_mutex down
 778 */
 779int reiserfs_removexattr(struct dentry *dentry, const char *name)
 780{
 781        const struct xattr_handler *handler;
 782        handler = find_xattr_handler_prefix(dentry->d_sb->s_xattr, name);
 783
 784        if (!handler || get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
 785                return -EOPNOTSUPP;
 786
 787        return handler->set(dentry, name, NULL, 0, XATTR_REPLACE, handler->flags);
 788}
 789
 790struct listxattr_buf {
 791        size_t size;
 792        size_t pos;
 793        char *buf;
 794        struct dentry *dentry;
 795};
 796
 797static int listxattr_filler(void *buf, const char *name, int namelen,
 798                            loff_t offset, u64 ino, unsigned int d_type)
 799{
 800        struct listxattr_buf *b = (struct listxattr_buf *)buf;
 801        size_t size;
 802        if (name[0] != '.' ||
 803            (namelen != 1 && (name[1] != '.' || namelen != 2))) {
 804                const struct xattr_handler *handler;
 805                handler = find_xattr_handler_prefix(b->dentry->d_sb->s_xattr,
 806                                                    name);
 807                if (!handler)   /* Unsupported xattr name */
 808                        return 0;
 809                if (b->buf) {
 810                        size = handler->list(b->dentry, b->buf + b->pos,
 811                                         b->size, name, namelen,
 812                                         handler->flags);
 813                        if (size > b->size)
 814                                return -ERANGE;
 815                } else {
 816                        size = handler->list(b->dentry, NULL, 0, name,
 817                                             namelen, handler->flags);
 818                }
 819
 820                b->pos += size;
 821        }
 822        return 0;
 823}
 824
 825/*
 826 * Inode operation listxattr()
 827 *
 828 * We totally ignore the generic listxattr here because it would be stupid
 829 * not to. Since the xattrs are organized in a directory, we can just
 830 * readdir to find them.
 831 */
 832ssize_t reiserfs_listxattr(struct dentry * dentry, char *buffer, size_t size)
 833{
 834        struct dentry *dir;
 835        int err = 0;
 836        loff_t pos = 0;
 837        struct listxattr_buf buf = {
 838                .dentry = dentry,
 839                .buf = buffer,
 840                .size = buffer ? size : 0,
 841        };
 842
 843        if (!dentry->d_inode)
 844                return -EINVAL;
 845
 846        if (!dentry->d_sb->s_xattr ||
 847            get_inode_sd_version(dentry->d_inode) == STAT_DATA_V1)
 848                return -EOPNOTSUPP;
 849
 850        dir = open_xa_dir(dentry->d_inode, XATTR_REPLACE);
 851        if (IS_ERR(dir)) {
 852                err = PTR_ERR(dir);
 853                if (err == -ENODATA)
 854                        err = 0;  /* Not an error if there aren't any xattrs */
 855                goto out;
 856        }
 857
 858        mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_XATTR);
 859        err = reiserfs_readdir_dentry(dir, &buf, listxattr_filler, &pos);
 860        mutex_unlock(&dir->d_inode->i_mutex);
 861
 862        if (!err)
 863                err = buf.pos;
 864
 865        dput(dir);
 866out:
 867        return err;
 868}
 869
 870static int create_privroot(struct dentry *dentry)
 871{
 872        int err;
 873        struct inode *inode = dentry->d_parent->d_inode;
 874        WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex));
 875
 876        err = xattr_mkdir(inode, dentry, 0700);
 877        if (err || !dentry->d_inode) {
 878                reiserfs_warning(dentry->d_sb, "jdm-20006",
 879                                 "xattrs/ACLs enabled and couldn't "
 880                                 "find/create .reiserfs_priv. "
 881                                 "Failing mount.");
 882                return -EOPNOTSUPP;
 883        }
 884
 885        dentry->d_inode->i_flags |= S_PRIVATE;
 886        reiserfs_info(dentry->d_sb, "Created %s - reserved for xattr "
 887                      "storage.\n", PRIVROOT_NAME);
 888
 889        return 0;
 890}
 891
 892#else
 893int __init reiserfs_xattr_register_handlers(void) { return 0; }
 894void reiserfs_xattr_unregister_handlers(void) {}
 895static int create_privroot(struct dentry *dentry) { return 0; }
 896#endif
 897
 898/* Actual operations that are exported to VFS-land */
 899static const struct xattr_handler *reiserfs_xattr_handlers[] = {
 900#ifdef CONFIG_REISERFS_FS_XATTR
 901        &reiserfs_xattr_user_handler,
 902        &reiserfs_xattr_trusted_handler,
 903#endif
 904#ifdef CONFIG_REISERFS_FS_SECURITY
 905        &reiserfs_xattr_security_handler,
 906#endif
 907#ifdef CONFIG_REISERFS_FS_POSIX_ACL
 908        &reiserfs_posix_acl_access_handler,
 909        &reiserfs_posix_acl_default_handler,
 910#endif
 911        NULL
 912};
 913
 914static int xattr_mount_check(struct super_block *s)
 915{
 916        /* We need generation numbers to ensure that the oid mapping is correct
 917         * v3.5 filesystems don't have them. */
 918        if (old_format_only(s)) {
 919                if (reiserfs_xattrs_optional(s)) {
 920                        /* Old format filesystem, but optional xattrs have
 921                         * been enabled. Error out. */
 922                        reiserfs_warning(s, "jdm-2005",
 923                                         "xattrs/ACLs not supported "
 924                                         "on pre-v3.6 format filesystems. "
 925                                         "Failing mount.");
 926                        return -EOPNOTSUPP;
 927                }
 928        }
 929
 930        return 0;
 931}
 932
 933int reiserfs_permission(struct inode *inode, int mask)
 934{
 935        /*
 936         * We don't do permission checks on the internal objects.
 937         * Permissions are determined by the "owning" object.
 938         */
 939        if (IS_PRIVATE(inode))
 940                return 0;
 941
 942        return generic_permission(inode, mask);
 943}
 944
 945static int xattr_hide_revalidate(struct dentry *dentry, unsigned int flags)
 946{
 947        return -EPERM;
 948}
 949
 950static const struct dentry_operations xattr_lookup_poison_ops = {
 951        .d_revalidate = xattr_hide_revalidate,
 952};
 953
 954int reiserfs_lookup_privroot(struct super_block *s)
 955{
 956        struct dentry *dentry;
 957        int err = 0;
 958
 959        /* If we don't have the privroot located yet - go find it */
 960        reiserfs_mutex_lock_safe(&s->s_root->d_inode->i_mutex, s);
 961        dentry = lookup_one_len(PRIVROOT_NAME, s->s_root,
 962                                strlen(PRIVROOT_NAME));
 963        if (!IS_ERR(dentry)) {
 964                REISERFS_SB(s)->priv_root = dentry;
 965                d_set_d_op(dentry, &xattr_lookup_poison_ops);
 966                if (dentry->d_inode)
 967                        dentry->d_inode->i_flags |= S_PRIVATE;
 968        } else
 969                err = PTR_ERR(dentry);
 970        mutex_unlock(&s->s_root->d_inode->i_mutex);
 971
 972        return err;
 973}
 974
 975/* We need to take a copy of the mount flags since things like
 976 * MS_RDONLY don't get set until *after* we're called.
 977 * mount_flags != mount_options */
 978int reiserfs_xattr_init(struct super_block *s, int mount_flags)
 979{
 980        int err = 0;
 981        struct dentry *privroot = REISERFS_SB(s)->priv_root;
 982
 983        err = xattr_mount_check(s);
 984        if (err)
 985                goto error;
 986
 987        if (!privroot->d_inode && !(mount_flags & MS_RDONLY)) {
 988                reiserfs_mutex_lock_safe(&s->s_root->d_inode->i_mutex, s);
 989                err = create_privroot(REISERFS_SB(s)->priv_root);
 990                mutex_unlock(&s->s_root->d_inode->i_mutex);
 991        }
 992
 993        if (privroot->d_inode) {
 994                s->s_xattr = reiserfs_xattr_handlers;
 995                reiserfs_mutex_lock_safe(&privroot->d_inode->i_mutex, s);
 996                if (!REISERFS_SB(s)->xattr_root) {
 997                        struct dentry *dentry;
 998                        dentry = lookup_one_len(XAROOT_NAME, privroot,
 999                                                strlen(XAROOT_NAME));
1000                        if (!IS_ERR(dentry))
1001                                REISERFS_SB(s)->xattr_root = dentry;
1002                        else
1003                                err = PTR_ERR(dentry);
1004                }
1005                mutex_unlock(&privroot->d_inode->i_mutex);
1006        }
1007
1008error:
1009        if (err) {
1010                clear_bit(REISERFS_XATTRS_USER, &(REISERFS_SB(s)->s_mount_opt));
1011                clear_bit(REISERFS_POSIXACL, &(REISERFS_SB(s)->s_mount_opt));
1012        }
1013
1014        /* The super_block MS_POSIXACL must mirror the (no)acl mount option. */
1015        if (reiserfs_posixacl(s))
1016                s->s_flags |= MS_POSIXACL;
1017        else
1018                s->s_flags &= ~MS_POSIXACL;
1019
1020        return err;
1021}
1022
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