fs/xfs/scrub/attr.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2017 Oracle.  All Rights Reserved.
   4  * Author: Darrick J. Wong <darrick.wong@oracle.com>
   5  */
   6 #include "xfs.h"
   7 #include "xfs_fs.h"
   8 #include "xfs_shared.h"
   9 #include "xfs_format.h"
  10 #include "xfs_trans_resv.h"
  11 #include "xfs_mount.h"
  12 #include "xfs_log_format.h"
  13 #include "xfs_inode.h"
  14 #include "xfs_da_format.h"
  15 #include "xfs_da_btree.h"
  16 #include "xfs_attr.h"
  17 #include "xfs_attr_leaf.h"
  18 #include "scrub/scrub.h"
  19 #include "scrub/common.h"
  20 #include "scrub/dabtree.h"
  21 #include "scrub/attr.h"
  22
  23 /*
  24  * Allocate enough memory to hold an attr value and attr block bitmaps,
  25  * reallocating the buffer if necessary.  Buffer contents are not preserved
  26  * across a reallocation.
  27  */
  28 int
  29 xchk_setup_xattr_buf(
  30         struct xfs_scrub        *sc,
  31         size_t                  value_size,
  32         xfs_km_flags_t          flags)
  33 {
  34         size_t                  sz;
  35         struct xchk_xattr_buf   *ab = sc->buf;
  36
  37         /*
  38          * We need enough space to read an xattr value from the file or enough
  39          * space to hold three copies of the xattr free space bitmap.  We don't
  40          * need the buffer space for both purposes at the same time.
  41          */
  42         sz = 3 * sizeof(long) * BITS_TO_LONGS(sc->mp->m_attr_geo->blksize);
  43         sz = max_t(size_t, sz, value_size);
  44
  45         /*
  46          * If there's already a buffer, figure out if we need to reallocate it
  47          * to accommodate a larger size.
  48          */
  49         if (ab) {
  50                 if (sz <= ab->sz)
  51                         return 0;
  52                 kmem_free(ab);
  53                 sc->buf = NULL;
  54         }
  55
  56         /*
  57          * Don't zero the buffer upon allocation to avoid runtime overhead.
  58          * All users must be careful never to read uninitialized contents.
  59          */
  60         ab = kmem_alloc_large(sizeof(*ab) + sz, flags);
  61         if (!ab)
  62                 return -ENOMEM;
  63
  64         ab->sz = sz;
  65         sc->buf = ab;
  66         return 0;
  67 }
  68
  69 /* Set us up to scrub an inode's extended attributes. */
  70 int
  71 xchk_setup_xattr(
  72         struct xfs_scrub        *sc,
  73         struct xfs_inode        *ip)
  74 {
  75         int                     error;
  76
  77         /*
  78          * We failed to get memory while checking attrs, so this time try to
  79          * get all the memory we're ever going to need.  Allocate the buffer
  80          * without the inode lock held, which means we can sleep.
  81          */
  82         if (sc->flags & XCHK_TRY_HARDER) {
  83                 error = xchk_setup_xattr_buf(sc, XATTR_SIZE_MAX, 0);
  84                 if (error)
  85                         return error;
  86         }
  87
  88         return xchk_setup_inode_contents(sc, ip, 0);
  89 }
  90
  91 /* Extended Attributes */
  92
  93 struct xchk_xattr {
  94         struct xfs_attr_list_context    context;
  95         struct xfs_scrub                *sc;
  96 };
  97
  98 /*
  99  * Check that an extended attribute key can be looked up by hash.
 100  *
 101  * We use the XFS attribute list iterator (i.e. xfs_attr_list_int_ilocked)
 102  * to call this function for every attribute key in an inode.  Once
 103  * we're here, we load the attribute value to see if any errors happen,
 104  * or if we get more or less data than we expected.
 105  */
 106 static void
 107 xchk_xattr_listent(
 108         struct xfs_attr_list_context    *context,
 109         int                             flags,
 110         unsigned char                   *name,
 111         int                             namelen,
 112         int                             valuelen)
 113 {
 114         struct xchk_xattr               *sx;
 115         struct xfs_da_args              args = { NULL };
 116         int                             error = 0;
 117
 118         sx = container_of(context, struct xchk_xattr, context);
 119
 120         if (xchk_should_terminate(sx->sc, &error)) {
 121                 context->seen_enough = error;
 122                 return;
 123         }
 124
 125         if (flags & XFS_ATTR_INCOMPLETE) {
 126                 /* Incomplete attr key, just mark the inode for preening. */
 127                 xchk_ino_set_preen(sx->sc, context->dp->i_ino);
 128                 return;
 129         }
 130
 131         /* Does this name make sense? */
 132         if (!xfs_attr_namecheck(name, namelen)) {
 133                 xchk_fblock_set_corrupt(sx->sc, XFS_ATTR_FORK, args.blkno);
 134                 return;
 135         }
 136
 137         /*
 138          * Try to allocate enough memory to extrat the attr value.  If that
 139          * doesn't work, we overload the seen_enough variable to convey
 140          * the error message back to the main scrub function.
 141          */
 142         error = xchk_setup_xattr_buf(sx->sc, valuelen, KM_MAYFAIL);
 143         if (error == -ENOMEM)
 144                 error = -EDEADLOCK;
 145         if (error) {
 146                 context->seen_enough = error;
 147                 return;
 148         }
 149
 150         args.flags = ATTR_KERNOTIME;
 151         if (flags & XFS_ATTR_ROOT)
 152                 args.flags |= ATTR_ROOT;
 153         else if (flags & XFS_ATTR_SECURE)
 154                 args.flags |= ATTR_SECURE;
 155         args.geo = context->dp->i_mount->m_attr_geo;
 156         args.whichfork = XFS_ATTR_FORK;
 157         args.dp = context->dp;
 158         args.name = name;
 159         args.namelen = namelen;
 160         args.hashval = xfs_da_hashname(args.name, args.namelen);
 161         args.trans = context->tp;
 162         args.value = xchk_xattr_valuebuf(sx->sc);
 163         args.valuelen = valuelen;
 164
 165         error = xfs_attr_get_ilocked(context->dp, &args);
 166         if (!xchk_fblock_process_error(sx->sc, XFS_ATTR_FORK, args.blkno,
 167                         &error))
 168                 goto fail_xref;
 169         if (args.valuelen != valuelen)
 170                 xchk_fblock_set_corrupt(sx->sc, XFS_ATTR_FORK,
 171                                              args.blkno);
 172 fail_xref:
 173         if (sx->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
 174                 context->seen_enough = 1;
 175         return;
 176 }
 177
 178 /*
 179  * Mark a range [start, start+len) in this map.  Returns true if the
 180  * region was free, and false if there's a conflict or a problem.
 181  *
 182  * Within a char, the lowest bit of the char represents the byte with
 183  * the smallest address
 184  */
 185 STATIC bool
 186 xchk_xattr_set_map(
 187         struct xfs_scrub        *sc,
 188         unsigned long           *map,
 189         unsigned int            start,
 190         unsigned int            len)
 191 {
 192         unsigned int            mapsize = sc->mp->m_attr_geo->blksize;
 193         bool                    ret = true;
 194
 195         if (start >= mapsize)
 196                 return false;
 197         if (start + len > mapsize) {
 198                 len = mapsize - start;
 199                 ret = false;
 200         }
 201
 202         if (find_next_bit(map, mapsize, start) < start + len)
 203                 ret = false;
 204         bitmap_set(map, start, len);
 205
 206         return ret;
 207 }
 208
 209 /*
 210  * Check the leaf freemap from the usage bitmap.  Returns false if the
 211  * attr freemap has problems or points to used space.
 212  */
 213 STATIC bool
 214 xchk_xattr_check_freemap(
 215         struct xfs_scrub                *sc,
 216         unsigned long                   *map,
 217         struct xfs_attr3_icleaf_hdr     *leafhdr)
 218 {
 219         unsigned long                   *freemap = xchk_xattr_freemap(sc);
 220         unsigned long                   *dstmap = xchk_xattr_dstmap(sc);
 221         unsigned int                    mapsize = sc->mp->m_attr_geo->blksize;
 222         int                             i;
 223
 224         /* Construct bitmap of freemap contents. */
 225         bitmap_zero(freemap, mapsize);
 226         for (i = 0; i < XFS_ATTR_LEAF_MAPSIZE; i++) {
 227                 if (!xchk_xattr_set_map(sc, freemap,
 228                                 leafhdr->freemap[i].base,
 229                                 leafhdr->freemap[i].size))
 230                         return false;
 231         }
 232
 233         /* Look for bits that are set in freemap and are marked in use. */
 234         return bitmap_and(dstmap, freemap, map, mapsize) == 0;
 235 }
 236
 237 /*
 238  * Check this leaf entry's relations to everything else.
 239  * Returns the number of bytes used for the name/value data.
 240  */
 241 STATIC void
 242 xchk_xattr_entry(
 243         struct xchk_da_btree            *ds,
 244         int                             level,
 245         char                            *buf_end,
 246         struct xfs_attr_leafblock       *leaf,
 247         struct xfs_attr3_icleaf_hdr     *leafhdr,
 248         struct xfs_attr_leaf_entry      *ent,
 249         int                             idx,
 250         unsigned int                    *usedbytes,
 251         __u32                           *last_hashval)
 252 {
 253         struct xfs_mount                *mp = ds->state->mp;
 254         unsigned long                   *usedmap = xchk_xattr_usedmap(ds->sc);
 255         char                            *name_end;
 256         struct xfs_attr_leaf_name_local *lentry;
 257         struct xfs_attr_leaf_name_remote *rentry;
 258         unsigned int                    nameidx;
 259         unsigned int                    namesize;
 260
 261         if (ent->pad2 != 0)
 262                 xchk_da_set_corrupt(ds, level);
 263
 264         /* Hash values in order? */
 265         if (be32_to_cpu(ent->hashval) < *last_hashval)
 266                 xchk_da_set_corrupt(ds, level);
 267         *last_hashval = be32_to_cpu(ent->hashval);
 268
 269         nameidx = be16_to_cpu(ent->nameidx);
 270         if (nameidx < leafhdr->firstused ||
 271             nameidx >= mp->m_attr_geo->blksize) {
 272                 xchk_da_set_corrupt(ds, level);
 273                 return;
 274         }
 275
 276         /* Check the name information. */
 277         if (ent->flags & XFS_ATTR_LOCAL) {
 278                 lentry = xfs_attr3_leaf_name_local(leaf, idx);
 279                 namesize = xfs_attr_leaf_entsize_local(lentry->namelen,
 280                                 be16_to_cpu(lentry->valuelen));
 281                 name_end = (char *)lentry + namesize;
 282                 if (lentry->namelen == 0)
 283                         xchk_da_set_corrupt(ds, level);
 284         } else {
 285                 rentry = xfs_attr3_leaf_name_remote(leaf, idx);
 286                 namesize = xfs_attr_leaf_entsize_remote(rentry->namelen);
 287                 name_end = (char *)rentry + namesize;
 288                 if (rentry->namelen == 0 || rentry->valueblk == 0)
 289                         xchk_da_set_corrupt(ds, level);
 290         }
 291         if (name_end > buf_end)
 292                 xchk_da_set_corrupt(ds, level);
 293
 294         if (!xchk_xattr_set_map(ds->sc, usedmap, nameidx, namesize))
 295                 xchk_da_set_corrupt(ds, level);
 296         if (!(ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
 297                 *usedbytes += namesize;
 298 }
 299
 300 /* Scrub an attribute leaf. */
 301 STATIC int
 302 xchk_xattr_block(
 303         struct xchk_da_btree            *ds,
 304         int                             level)
 305 {
 306         struct xfs_attr3_icleaf_hdr     leafhdr;
 307         struct xfs_mount                *mp = ds->state->mp;
 308         struct xfs_da_state_blk         *blk = &ds->state->path.blk[level];
 309         struct xfs_buf                  *bp = blk->bp;
 310         xfs_dablk_t                     *last_checked = ds->private;
 311         struct xfs_attr_leafblock       *leaf = bp->b_addr;
 312         struct xfs_attr_leaf_entry      *ent;
 313         struct xfs_attr_leaf_entry      *entries;
 314         unsigned long                   *usedmap;
 315         char                            *buf_end;
 316         size_t                          off;
 317         __u32                           last_hashval = 0;
 318         unsigned int                    usedbytes = 0;
 319         unsigned int                    hdrsize;
 320         int                             i;
 321         int                             error;
 322
 323         if (*last_checked == blk->blkno)
 324                 return 0;
 325
 326         /* Allocate memory for block usage checking. */
 327         error = xchk_setup_xattr_buf(ds->sc, 0, KM_MAYFAIL);
 328         if (error == -ENOMEM)
 329                 return -EDEADLOCK;
 330         if (error)
 331                 return error;
 332         usedmap = xchk_xattr_usedmap(ds->sc);
 333
 334         *last_checked = blk->blkno;
 335         bitmap_zero(usedmap, mp->m_attr_geo->blksize);
 336
 337         /* Check all the padding. */
 338         if (xfs_sb_version_hascrc(&ds->sc->mp->m_sb)) {
 339                 struct xfs_attr3_leafblock      *leaf = bp->b_addr;
 340
 341                 if (leaf->hdr.pad1 != 0 || leaf->hdr.pad2 != 0 ||
 342                     leaf->hdr.info.hdr.pad != 0)
 343                         xchk_da_set_corrupt(ds, level);
 344         } else {
 345                 if (leaf->hdr.pad1 != 0 || leaf->hdr.info.pad != 0)
 346                         xchk_da_set_corrupt(ds, level);
 347         }
 348
 349         /* Check the leaf header */
 350         xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &leafhdr, leaf);
 351         hdrsize = xfs_attr3_leaf_hdr_size(leaf);
 352
 353         if (leafhdr.usedbytes > mp->m_attr_geo->blksize)
 354                 xchk_da_set_corrupt(ds, level);
 355         if (leafhdr.firstused > mp->m_attr_geo->blksize)
 356                 xchk_da_set_corrupt(ds, level);
 357         if (leafhdr.firstused < hdrsize)
 358                 xchk_da_set_corrupt(ds, level);
 359         if (!xchk_xattr_set_map(ds->sc, usedmap, 0, hdrsize))
 360                 xchk_da_set_corrupt(ds, level);
 361
 362         if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
 363                 goto out;
 364
 365         entries = xfs_attr3_leaf_entryp(leaf);
 366         if ((char *)&entries[leafhdr.count] > (char *)leaf + leafhdr.firstused)
 367                 xchk_da_set_corrupt(ds, level);
 368
 369         buf_end = (char *)bp->b_addr + mp->m_attr_geo->blksize;
 370         for (i = 0, ent = entries; i < leafhdr.count; ent++, i++) {
 371                 /* Mark the leaf entry itself. */
 372                 off = (char *)ent - (char *)leaf;
 373                 if (!xchk_xattr_set_map(ds->sc, usedmap, off,
 374                                 sizeof(xfs_attr_leaf_entry_t))) {
 375                         xchk_da_set_corrupt(ds, level);
 376                         goto out;
 377                 }
 378
 379                 /* Check the entry and nameval. */
 380                 xchk_xattr_entry(ds, level, buf_end, leaf, &leafhdr,
 381                                 ent, i, &usedbytes, &last_hashval);
 382
 383                 if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
 384                         goto out;
 385         }
 386
 387         if (!xchk_xattr_check_freemap(ds->sc, usedmap, &leafhdr))
 388                 xchk_da_set_corrupt(ds, level);
 389
 390         if (leafhdr.usedbytes != usedbytes)
 391                 xchk_da_set_corrupt(ds, level);
 392
 393 out:
 394         return 0;
 395 }
 396
 397 /* Scrub a attribute btree record. */
 398 STATIC int
 399 xchk_xattr_rec(
 400         struct xchk_da_btree            *ds,
 401         int                             level,
 402         void                            *rec)
 403 {
 404         struct xfs_mount                *mp = ds->state->mp;
 405         struct xfs_attr_leaf_entry      *ent = rec;
 406         struct xfs_da_state_blk         *blk;
 407         struct xfs_attr_leaf_name_local *lentry;
 408         struct xfs_attr_leaf_name_remote        *rentry;
 409         struct xfs_buf                  *bp;
 410         xfs_dahash_t                    calc_hash;
 411         xfs_dahash_t                    hash;
 412         int                             nameidx;
 413         int                             hdrsize;
 414         unsigned int                    badflags;
 415         int                             error;
 416
 417         blk = &ds->state->path.blk[level];
 418
 419         /* Check the whole block, if necessary. */
 420         error = xchk_xattr_block(ds, level);
 421         if (error)
 422                 goto out;
 423         if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
 424                 goto out;
 425
 426         /* Check the hash of the entry. */
 427         error = xchk_da_btree_hash(ds, level, &ent->hashval);
 428         if (error)
 429                 goto out;
 430
 431         /* Find the attr entry's location. */
 432         bp = blk->bp;
 433         hdrsize = xfs_attr3_leaf_hdr_size(bp->b_addr);
 434         nameidx = be16_to_cpu(ent->nameidx);
 435         if (nameidx < hdrsize || nameidx >= mp->m_attr_geo->blksize) {
 436                 xchk_da_set_corrupt(ds, level);
 437                 goto out;
 438         }
 439
 440         /* Retrieve the entry and check it. */
 441         hash = be32_to_cpu(ent->hashval);
 442         badflags = ~(XFS_ATTR_LOCAL | XFS_ATTR_ROOT | XFS_ATTR_SECURE |
 443                         XFS_ATTR_INCOMPLETE);
 444         if ((ent->flags & badflags) != 0)
 445                 xchk_da_set_corrupt(ds, level);
 446         if (ent->flags & XFS_ATTR_LOCAL) {
 447                 lentry = (struct xfs_attr_leaf_name_local *)
 448                                 (((char *)bp->b_addr) + nameidx);
 449                 if (lentry->namelen <= 0) {
 450                         xchk_da_set_corrupt(ds, level);
 451                         goto out;
 452                 }
 453                 calc_hash = xfs_da_hashname(lentry->nameval, lentry->namelen);
 454         } else {
 455                 rentry = (struct xfs_attr_leaf_name_remote *)
 456                                 (((char *)bp->b_addr) + nameidx);
 457                 if (rentry->namelen <= 0) {
 458                         xchk_da_set_corrupt(ds, level);
 459                         goto out;
 460                 }
 461                 calc_hash = xfs_da_hashname(rentry->name, rentry->namelen);
 462         }
 463         if (calc_hash != hash)
 464                 xchk_da_set_corrupt(ds, level);
 465
 466 out:
 467         return error;
 468 }
 469
 470 /* Scrub the extended attribute metadata. */
 471 int
 472 xchk_xattr(
 473         struct xfs_scrub                *sc)
 474 {
 475         struct xchk_xattr               sx;
 476         struct attrlist_cursor_kern     cursor = { 0 };
 477         xfs_dablk_t                     last_checked = -1U;
 478         int                             error = 0;
 479
 480         if (!xfs_inode_hasattr(sc->ip))
 481                 return -ENOENT;
 482
 483         memset(&sx, 0, sizeof(sx));
 484         /* Check attribute tree structure */
 485         error = xchk_da_btree(sc, XFS_ATTR_FORK, xchk_xattr_rec,
 486                         &last_checked);
 487         if (error)
 488                 goto out;
 489
 490         if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
 491                 goto out;
 492
 493         /* Check that every attr key can also be looked up by hash. */
 494         sx.context.dp = sc->ip;
 495         sx.context.cursor = &cursor;
 496         sx.context.resynch = 1;
 497         sx.context.put_listent = xchk_xattr_listent;
 498         sx.context.tp = sc->tp;
 499         sx.context.flags = ATTR_INCOMPLETE;
 500         sx.sc = sc;
 501
 502         /*
 503          * Look up every xattr in this file by name.
 504          *
 505          * Use the backend implementation of xfs_attr_list to call
 506          * xchk_xattr_listent on every attribute key in this inode.
 507          * In other words, we use the same iterator/callback mechanism
 508          * that listattr uses to scrub extended attributes, though in our
 509          * _listent function, we check the value of the attribute.
 510          *
 511          * The VFS only locks i_rwsem when modifying attrs, so keep all
 512          * three locks held because that's the only way to ensure we're
 513          * the only thread poking into the da btree.  We traverse the da
 514          * btree while holding a leaf buffer locked for the xattr name
 515          * iteration, which doesn't really follow the usual buffer
 516          * locking order.
 517          */
 518         error = xfs_attr_list_int_ilocked(&sx.context);
 519         if (!xchk_fblock_process_error(sc, XFS_ATTR_FORK, 0, &error))
 520                 goto out;
 521
 522         /* Did our listent function try to return any errors? */
 523         if (sx.context.seen_enough < 0)
 524                 error = sx.context.seen_enough;
 525 out:
 526         return error;
 527 }