fs/xfs/scrub/attr.c

   1 /*
   2  * Copyright (C) 2017 Oracle.  All Rights Reserved.
   3  *
   4  * Author: Darrick J. Wong <darrick.wong@oracle.com>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version 2
   9  * of the License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it would be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write the Free Software Foundation,
  18  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA.
  19  */
  20 #include "xfs.h"
  21 #include "xfs_fs.h"
  22 #include "xfs_shared.h"
  23 #include "xfs_format.h"
  24 #include "xfs_trans_resv.h"
  25 #include "xfs_mount.h"
  26 #include "xfs_defer.h"
  27 #include "xfs_btree.h"
  28 #include "xfs_bit.h"
  29 #include "xfs_log_format.h"
  30 #include "xfs_trans.h"
  31 #include "xfs_sb.h"
  32 #include "xfs_inode.h"
  33 #include "xfs_da_format.h"
  34 #include "xfs_da_btree.h"
  35 #include "xfs_dir2.h"
  36 #include "xfs_attr.h"
  37 #include "xfs_attr_leaf.h"
  38 #include "scrub/xfs_scrub.h"
  39 #include "scrub/scrub.h"
  40 #include "scrub/common.h"
  41 #include "scrub/dabtree.h"
  42 #include "scrub/trace.h"
  43
  44 #include <linux/posix_acl_xattr.h>
  45 #include <linux/xattr.h>
  46
  47 /* Set us up to scrub an inode's extended attributes. */
  48 int
  49 xfs_scrub_setup_xattr(
  50         struct xfs_scrub_context        *sc,
  51         struct xfs_inode                *ip)
  52 {
  53         size_t                          sz;
  54
  55         /*
  56          * Allocate the buffer without the inode lock held.  We need enough
  57          * space to read every xattr value in the file or enough space to
  58          * hold three copies of the xattr free space bitmap.  (Not both at
  59          * the same time.)
  60          */
  61         sz = max_t(size_t, XATTR_SIZE_MAX, 3 * sizeof(long) *
  62                         BITS_TO_LONGS(sc->mp->m_attr_geo->blksize));
  63         sc->buf = kmem_zalloc_large(sz, KM_SLEEP);
  64         if (!sc->buf)
  65                 return -ENOMEM;
  66
  67         return xfs_scrub_setup_inode_contents(sc, ip, 0);
  68 }
  69
  70 /* Extended Attributes */
  71
  72 struct xfs_scrub_xattr {
  73         struct xfs_attr_list_context    context;
  74         struct xfs_scrub_context        *sc;
  75 };
  76
  77 /*
  78  * Check that an extended attribute key can be looked up by hash.
  79  *
  80  * We use the XFS attribute list iterator (i.e. xfs_attr_list_int_ilocked)
  81  * to call this function for every attribute key in an inode.  Once
  82  * we're here, we load the attribute value to see if any errors happen,
  83  * or if we get more or less data than we expected.
  84  */
  85 static void
  86 xfs_scrub_xattr_listent(
  87         struct xfs_attr_list_context    *context,
  88         int                             flags,
  89         unsigned char                   *name,
  90         int                             namelen,
  91         int                             valuelen)
  92 {
  93         struct xfs_scrub_xattr          *sx;
  94         struct xfs_da_args              args = { NULL };
  95         int                             error = 0;
  96
  97         sx = container_of(context, struct xfs_scrub_xattr, context);
  98
  99         if (flags & XFS_ATTR_INCOMPLETE) {
 100                 /* Incomplete attr key, just mark the inode for preening. */
 101                 xfs_scrub_ino_set_preen(sx->sc, context->dp->i_ino, NULL);
 102                 return;
 103         }
 104
 105         args.flags = ATTR_KERNOTIME;
 106         if (flags & XFS_ATTR_ROOT)
 107                 args.flags |= ATTR_ROOT;
 108         else if (flags & XFS_ATTR_SECURE)
 109                 args.flags |= ATTR_SECURE;
 110         args.geo = context->dp->i_mount->m_attr_geo;
 111         args.whichfork = XFS_ATTR_FORK;
 112         args.dp = context->dp;
 113         args.name = name;
 114         args.namelen = namelen;
 115         args.hashval = xfs_da_hashname(args.name, args.namelen);
 116         args.trans = context->tp;
 117         args.value = sx->sc->buf;
 118         args.valuelen = XATTR_SIZE_MAX;
 119
 120         error = xfs_attr_get_ilocked(context->dp, &args);
 121         if (error == -EEXIST)
 122                 error = 0;
 123         if (!xfs_scrub_fblock_process_error(sx->sc, XFS_ATTR_FORK, args.blkno,
 124                         &error))
 125                 goto fail_xref;
 126         if (args.valuelen != valuelen)
 127                 xfs_scrub_fblock_set_corrupt(sx->sc, XFS_ATTR_FORK,
 128                                              args.blkno);
 129
 130 fail_xref:
 131         return;
 132 }
 133
 134 /*
 135  * Mark a range [start, start+len) in this map.  Returns true if the
 136  * region was free, and false if there's a conflict or a problem.
 137  *
 138  * Within a char, the lowest bit of the char represents the byte with
 139  * the smallest address
 140  */
 141 STATIC bool
 142 xfs_scrub_xattr_set_map(
 143         struct xfs_scrub_context        *sc,
 144         unsigned long                   *map,
 145         unsigned int                    start,
 146         unsigned int                    len)
 147 {
 148         unsigned int                    mapsize = sc->mp->m_attr_geo->blksize;
 149         bool                            ret = true;
 150
 151         if (start >= mapsize)
 152                 return false;
 153         if (start + len > mapsize) {
 154                 len = mapsize - start;
 155                 ret = false;
 156         }
 157
 158         if (find_next_bit(map, mapsize, start) < start + len)
 159                 ret = false;
 160         bitmap_set(map, start, len);
 161
 162         return ret;
 163 }
 164
 165 /*
 166  * Check the leaf freemap from the usage bitmap.  Returns false if the
 167  * attr freemap has problems or points to used space.
 168  */
 169 STATIC bool
 170 xfs_scrub_xattr_check_freemap(
 171         struct xfs_scrub_context        *sc,
 172         unsigned long                   *map,
 173         struct xfs_attr3_icleaf_hdr     *leafhdr)
 174 {
 175         unsigned long                   *freemap;
 176         unsigned long                   *dstmap;
 177         unsigned int                    mapsize = sc->mp->m_attr_geo->blksize;
 178         int                             i;
 179
 180         /* Construct bitmap of freemap contents. */
 181         freemap = (unsigned long *)sc->buf + BITS_TO_LONGS(mapsize);
 182         bitmap_zero(freemap, mapsize);
 183         for (i = 0; i < XFS_ATTR_LEAF_MAPSIZE; i++) {
 184                 if (!xfs_scrub_xattr_set_map(sc, freemap,
 185                                 leafhdr->freemap[i].base,
 186                                 leafhdr->freemap[i].size))
 187                         return false;
 188         }
 189
 190         /* Look for bits that are set in freemap and are marked in use. */
 191         dstmap = freemap + BITS_TO_LONGS(mapsize);
 192         return bitmap_and(dstmap, freemap, map, mapsize) == 0;
 193 }
 194
 195 /*
 196  * Check this leaf entry's relations to everything else.
 197  * Returns the number of bytes used for the name/value data.
 198  */
 199 STATIC void
 200 xfs_scrub_xattr_entry(
 201         struct xfs_scrub_da_btree       *ds,
 202         int                             level,
 203         char                            *buf_end,
 204         struct xfs_attr_leafblock       *leaf,
 205         struct xfs_attr3_icleaf_hdr     *leafhdr,
 206         unsigned long                   *usedmap,
 207         struct xfs_attr_leaf_entry      *ent,
 208         int                             idx,
 209         unsigned int                    *usedbytes,
 210         __u32                           *last_hashval)
 211 {
 212         struct xfs_mount                *mp = ds->state->mp;
 213         char                            *name_end;
 214         struct xfs_attr_leaf_name_local *lentry;
 215         struct xfs_attr_leaf_name_remote *rentry;
 216         unsigned int                    nameidx;
 217         unsigned int                    namesize;
 218
 219         if (ent->pad2 != 0)
 220                 xfs_scrub_da_set_corrupt(ds, level);
 221
 222         /* Hash values in order? */
 223         if (be32_to_cpu(ent->hashval) < *last_hashval)
 224                 xfs_scrub_da_set_corrupt(ds, level);
 225         *last_hashval = be32_to_cpu(ent->hashval);
 226
 227         nameidx = be16_to_cpu(ent->nameidx);
 228         if (nameidx < leafhdr->firstused ||
 229             nameidx >= mp->m_attr_geo->blksize) {
 230                 xfs_scrub_da_set_corrupt(ds, level);
 231                 return;
 232         }
 233
 234         /* Check the name information. */
 235         if (ent->flags & XFS_ATTR_LOCAL) {
 236                 lentry = xfs_attr3_leaf_name_local(leaf, idx);
 237                 namesize = xfs_attr_leaf_entsize_local(lentry->namelen,
 238                                 be16_to_cpu(lentry->valuelen));
 239                 name_end = (char *)lentry + namesize;
 240                 if (lentry->namelen == 0)
 241                         xfs_scrub_da_set_corrupt(ds, level);
 242         } else {
 243                 rentry = xfs_attr3_leaf_name_remote(leaf, idx);
 244                 namesize = xfs_attr_leaf_entsize_remote(rentry->namelen);
 245                 name_end = (char *)rentry + namesize;
 246                 if (rentry->namelen == 0 || rentry->valueblk == 0)
 247                         xfs_scrub_da_set_corrupt(ds, level);
 248         }
 249         if (name_end > buf_end)
 250                 xfs_scrub_da_set_corrupt(ds, level);
 251
 252         if (!xfs_scrub_xattr_set_map(ds->sc, usedmap, nameidx, namesize))
 253                 xfs_scrub_da_set_corrupt(ds, level);
 254         if (!(ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
 255                 *usedbytes += namesize;
 256 }
 257
 258 /* Scrub an attribute leaf. */
 259 STATIC int
 260 xfs_scrub_xattr_block(
 261         struct xfs_scrub_da_btree       *ds,
 262         int                             level)
 263 {
 264         struct xfs_attr3_icleaf_hdr     leafhdr;
 265         struct xfs_mount                *mp = ds->state->mp;
 266         struct xfs_da_state_blk         *blk = &ds->state->path.blk[level];
 267         struct xfs_buf                  *bp = blk->bp;
 268         xfs_dablk_t                     *last_checked = ds->private;
 269         struct xfs_attr_leafblock       *leaf = bp->b_addr;
 270         struct xfs_attr_leaf_entry      *ent;
 271         struct xfs_attr_leaf_entry      *entries;
 272         unsigned long                   *usedmap = ds->sc->buf;
 273         char                            *buf_end;
 274         size_t                          off;
 275         __u32                           last_hashval = 0;
 276         unsigned int                    usedbytes = 0;
 277         unsigned int                    hdrsize;
 278         int                             i;
 279
 280         if (*last_checked == blk->blkno)
 281                 return 0;
 282         *last_checked = blk->blkno;
 283         bitmap_zero(usedmap, mp->m_attr_geo->blksize);
 284
 285         /* Check all the padding. */
 286         if (xfs_sb_version_hascrc(&ds->sc->mp->m_sb)) {
 287                 struct xfs_attr3_leafblock      *leaf = bp->b_addr;
 288
 289                 if (leaf->hdr.pad1 != 0 || leaf->hdr.pad2 != 0 ||
 290                     leaf->hdr.info.hdr.pad != 0)
 291                         xfs_scrub_da_set_corrupt(ds, level);
 292         } else {
 293                 if (leaf->hdr.pad1 != 0 || leaf->hdr.info.pad != 0)
 294                         xfs_scrub_da_set_corrupt(ds, level);
 295         }
 296
 297         /* Check the leaf header */
 298         xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &leafhdr, leaf);
 299         hdrsize = xfs_attr3_leaf_hdr_size(leaf);
 300
 301         if (leafhdr.usedbytes > mp->m_attr_geo->blksize)
 302                 xfs_scrub_da_set_corrupt(ds, level);
 303         if (leafhdr.firstused > mp->m_attr_geo->blksize)
 304                 xfs_scrub_da_set_corrupt(ds, level);
 305         if (leafhdr.firstused < hdrsize)
 306                 xfs_scrub_da_set_corrupt(ds, level);
 307         if (!xfs_scrub_xattr_set_map(ds->sc, usedmap, 0, hdrsize))
 308                 xfs_scrub_da_set_corrupt(ds, level);
 309
 310         if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
 311                 goto out;
 312
 313         entries = xfs_attr3_leaf_entryp(leaf);
 314         if ((char *)&entries[leafhdr.count] > (char *)leaf + leafhdr.firstused)
 315                 xfs_scrub_da_set_corrupt(ds, level);
 316
 317         buf_end = (char *)bp->b_addr + mp->m_attr_geo->blksize;
 318         for (i = 0, ent = entries; i < leafhdr.count; ent++, i++) {
 319                 /* Mark the leaf entry itself. */
 320                 off = (char *)ent - (char *)leaf;
 321                 if (!xfs_scrub_xattr_set_map(ds->sc, usedmap, off,
 322                                 sizeof(xfs_attr_leaf_entry_t))) {
 323                         xfs_scrub_da_set_corrupt(ds, level);
 324                         goto out;
 325                 }
 326
 327                 /* Check the entry and nameval. */
 328                 xfs_scrub_xattr_entry(ds, level, buf_end, leaf, &leafhdr,
 329                                 usedmap, ent, i, &usedbytes, &last_hashval);
 330
 331                 if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
 332                         goto out;
 333         }
 334
 335         if (!xfs_scrub_xattr_check_freemap(ds->sc, usedmap, &leafhdr))
 336                 xfs_scrub_da_set_corrupt(ds, level);
 337
 338         if (leafhdr.usedbytes != usedbytes)
 339                 xfs_scrub_da_set_corrupt(ds, level);
 340
 341 out:
 342         return 0;
 343 }
 344
 345 /* Scrub a attribute btree record. */
 346 STATIC int
 347 xfs_scrub_xattr_rec(
 348         struct xfs_scrub_da_btree       *ds,
 349         int                             level,
 350         void                            *rec)
 351 {
 352         struct xfs_mount                *mp = ds->state->mp;
 353         struct xfs_attr_leaf_entry      *ent = rec;
 354         struct xfs_da_state_blk         *blk;
 355         struct xfs_attr_leaf_name_local *lentry;
 356         struct xfs_attr_leaf_name_remote        *rentry;
 357         struct xfs_buf                  *bp;
 358         xfs_dahash_t                    calc_hash;
 359         xfs_dahash_t                    hash;
 360         int                             nameidx;
 361         int                             hdrsize;
 362         unsigned int                    badflags;
 363         int                             error;
 364
 365         blk = &ds->state->path.blk[level];
 366
 367         /* Check the whole block, if necessary. */
 368         error = xfs_scrub_xattr_block(ds, level);
 369         if (error)
 370                 goto out;
 371         if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
 372                 goto out;
 373
 374         /* Check the hash of the entry. */
 375         error = xfs_scrub_da_btree_hash(ds, level, &ent->hashval);
 376         if (error)
 377                 goto out;
 378
 379         /* Find the attr entry's location. */
 380         bp = blk->bp;
 381         hdrsize = xfs_attr3_leaf_hdr_size(bp->b_addr);
 382         nameidx = be16_to_cpu(ent->nameidx);
 383         if (nameidx < hdrsize || nameidx >= mp->m_attr_geo->blksize) {
 384                 xfs_scrub_da_set_corrupt(ds, level);
 385                 goto out;
 386         }
 387
 388         /* Retrieve the entry and check it. */
 389         hash = be32_to_cpu(ent->hashval);
 390         badflags = ~(XFS_ATTR_LOCAL | XFS_ATTR_ROOT | XFS_ATTR_SECURE |
 391                         XFS_ATTR_INCOMPLETE);
 392         if ((ent->flags & badflags) != 0)
 393                 xfs_scrub_da_set_corrupt(ds, level);
 394         if (ent->flags & XFS_ATTR_LOCAL) {
 395                 lentry = (struct xfs_attr_leaf_name_local *)
 396                                 (((char *)bp->b_addr) + nameidx);
 397                 if (lentry->namelen <= 0) {
 398                         xfs_scrub_da_set_corrupt(ds, level);
 399                         goto out;
 400                 }
 401                 calc_hash = xfs_da_hashname(lentry->nameval, lentry->namelen);
 402         } else {
 403                 rentry = (struct xfs_attr_leaf_name_remote *)
 404                                 (((char *)bp->b_addr) + nameidx);
 405                 if (rentry->namelen <= 0) {
 406                         xfs_scrub_da_set_corrupt(ds, level);
 407                         goto out;
 408                 }
 409                 calc_hash = xfs_da_hashname(rentry->name, rentry->namelen);
 410         }
 411         if (calc_hash != hash)
 412                 xfs_scrub_da_set_corrupt(ds, level);
 413
 414 out:
 415         return error;
 416 }
 417
 418 /* Scrub the extended attribute metadata. */
 419 int
 420 xfs_scrub_xattr(
 421         struct xfs_scrub_context        *sc)
 422 {
 423         struct xfs_scrub_xattr          sx;
 424         struct attrlist_cursor_kern     cursor = { 0 };
 425         xfs_dablk_t                     last_checked = -1U;
 426         int                             error = 0;
 427
 428         if (!xfs_inode_hasattr(sc->ip))
 429                 return -ENOENT;
 430
 431         memset(&sx, 0, sizeof(sx));
 432         /* Check attribute tree structure */
 433         error = xfs_scrub_da_btree(sc, XFS_ATTR_FORK, xfs_scrub_xattr_rec,
 434                         &last_checked);
 435         if (error)
 436                 goto out;
 437
 438         if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
 439                 goto out;
 440
 441         /* Check that every attr key can also be looked up by hash. */
 442         sx.context.dp = sc->ip;
 443         sx.context.cursor = &cursor;
 444         sx.context.resynch = 1;
 445         sx.context.put_listent = xfs_scrub_xattr_listent;
 446         sx.context.tp = sc->tp;
 447         sx.context.flags = ATTR_INCOMPLETE;
 448         sx.sc = sc;
 449
 450         /*
 451          * Look up every xattr in this file by name.
 452          *
 453          * Use the backend implementation of xfs_attr_list to call
 454          * xfs_scrub_xattr_listent on every attribute key in this inode.
 455          * In other words, we use the same iterator/callback mechanism
 456          * that listattr uses to scrub extended attributes, though in our
 457          * _listent function, we check the value of the attribute.
 458          *
 459          * The VFS only locks i_rwsem when modifying attrs, so keep all
 460          * three locks held because that's the only way to ensure we're
 461          * the only thread poking into the da btree.  We traverse the da
 462          * btree while holding a leaf buffer locked for the xattr name
 463          * iteration, which doesn't really follow the usual buffer
 464          * locking order.
 465          */
 466         error = xfs_attr_list_int_ilocked(&sx.context);
 467         if (!xfs_scrub_fblock_process_error(sc, XFS_ATTR_FORK, 0, &error))
 468                 goto out;
 469 out:
 470         return error;
 471 }