fs/xfs/xfs_symlink.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2000-2006 Silicon Graphics, Inc.
   4  * Copyright (c) 2012-2013 Red Hat, Inc.
   5  * All rights reserved.
   6  */
   7 #include "xfs.h"
   8 #include "xfs_shared.h"
   9 #include "xfs_fs.h"
  10 #include "xfs_format.h"
  11 #include "xfs_log_format.h"
  12 #include "xfs_trans_resv.h"
  13 #include "xfs_bit.h"
  14 #include "xfs_mount.h"
  15 #include "xfs_da_format.h"
  16 #include "xfs_da_btree.h"
  17 #include "xfs_defer.h"
  18 #include "xfs_dir2.h"
  19 #include "xfs_inode.h"
  20 #include "xfs_ialloc.h"
  21 #include "xfs_alloc.h"
  22 #include "xfs_bmap.h"
  23 #include "xfs_bmap_btree.h"
  24 #include "xfs_bmap_util.h"
  25 #include "xfs_error.h"
  26 #include "xfs_quota.h"
  27 #include "xfs_trans_space.h"
  28 #include "xfs_trace.h"
  29 #include "xfs_symlink.h"
  30 #include "xfs_trans.h"
  31 #include "xfs_log.h"
  32
  33 /* ----- Kernel only functions below ----- */
  34 int
  35 xfs_readlink_bmap_ilocked(
  36         struct xfs_inode        *ip,
  37         char                    *link)
  38 {
  39         struct xfs_mount        *mp = ip->i_mount;
  40         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
  41         struct xfs_buf          *bp;
  42         xfs_daddr_t             d;
  43         char                    *cur_chunk;
  44         int                     pathlen = ip->i_d.di_size;
  45         int                     nmaps = XFS_SYMLINK_MAPS;
  46         int                     byte_cnt;
  47         int                     n;
  48         int                     error = 0;
  49         int                     fsblocks = 0;
  50         int                     offset;
  51
  52         ASSERT(xfs_isilocked(ip, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
  53
  54         fsblocks = xfs_symlink_blocks(mp, pathlen);
  55         error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0);
  56         if (error)
  57                 goto out;
  58
  59         offset = 0;
  60         for (n = 0; n < nmaps; n++) {
  61                 d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
  62                 byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
  63
  64                 bp = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
  65                                   &xfs_symlink_buf_ops);
  66                 if (!bp)
  67                         return -ENOMEM;
  68                 error = bp->b_error;
  69                 if (error) {
  70                         xfs_buf_ioerror_alert(bp, __func__);
  71                         xfs_buf_relse(bp);
  72
  73                         /* bad CRC means corrupted metadata */
  74                         if (error == -EFSBADCRC)
  75                                 error = -EFSCORRUPTED;
  76                         goto out;
  77                 }
  78                 byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
  79                 if (pathlen < byte_cnt)
  80                         byte_cnt = pathlen;
  81
  82                 cur_chunk = bp->b_addr;
  83                 if (xfs_sb_version_hascrc(&mp->m_sb)) {
  84                         if (!xfs_symlink_hdr_ok(ip->i_ino, offset,
  85                                                         byte_cnt, bp)) {
  86                                 error = -EFSCORRUPTED;
  87                                 xfs_alert(mp,
  88 "symlink header does not match required off/len/owner (0x%x/Ox%x,0x%llx)",
  89                                         offset, byte_cnt, ip->i_ino);
  90                                 xfs_buf_relse(bp);
  91                                 goto out;
  92
  93                         }
  94
  95                         cur_chunk += sizeof(struct xfs_dsymlink_hdr);
  96                 }
  97
  98                 memcpy(link + offset, cur_chunk, byte_cnt);
  99
 100                 pathlen -= byte_cnt;
 101                 offset += byte_cnt;
 102
 103                 xfs_buf_relse(bp);
 104         }
 105         ASSERT(pathlen == 0);
 106
 107         link[ip->i_d.di_size] = '\0';
 108         error = 0;
 109
 110  out:
 111         return error;
 112 }
 113
 114 int
 115 xfs_readlink(
 116         struct xfs_inode *ip,
 117         char            *link)
 118 {
 119         struct xfs_mount *mp = ip->i_mount;
 120         xfs_fsize_t     pathlen;
 121         int             error = 0;
 122
 123         trace_xfs_readlink(ip);
 124
 125         ASSERT(!(ip->i_df.if_flags & XFS_IFINLINE));
 126
 127         if (XFS_FORCED_SHUTDOWN(mp))
 128                 return -EIO;
 129
 130         xfs_ilock(ip, XFS_ILOCK_SHARED);
 131
 132         pathlen = ip->i_d.di_size;
 133         if (!pathlen)
 134                 goto out;
 135
 136         if (pathlen < 0 || pathlen > XFS_SYMLINK_MAXLEN) {
 137                 xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)",
 138                          __func__, (unsigned long long) ip->i_ino,
 139                          (long long) pathlen);
 140                 ASSERT(0);
 141                 error = -EFSCORRUPTED;
 142                 goto out;
 143         }
 144
 145
 146         error = xfs_readlink_bmap_ilocked(ip, link);
 147
 148  out:
 149         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 150         return error;
 151 }
 152
 153 int
 154 xfs_symlink(
 155         struct xfs_inode        *dp,
 156         struct xfs_name         *link_name,
 157         const char              *target_path,
 158         umode_t                 mode,
 159         struct xfs_inode        **ipp)
 160 {
 161         struct xfs_mount        *mp = dp->i_mount;
 162         struct xfs_trans        *tp = NULL;
 163         struct xfs_inode        *ip = NULL;
 164         int                     error = 0;
 165         int                     pathlen;
 166         struct xfs_defer_ops    dfops;
 167         xfs_fsblock_t           first_block;
 168         bool                    unlock_dp_on_error = false;
 169         xfs_fileoff_t           first_fsb;
 170         xfs_filblks_t           fs_blocks;
 171         int                     nmaps;
 172         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
 173         xfs_daddr_t             d;
 174         const char              *cur_chunk;
 175         int                     byte_cnt;
 176         int                     n;
 177         xfs_buf_t               *bp;
 178         prid_t                  prid;
 179         struct xfs_dquot        *udqp = NULL;
 180         struct xfs_dquot        *gdqp = NULL;
 181         struct xfs_dquot        *pdqp = NULL;
 182         uint                    resblks;
 183
 184         *ipp = NULL;
 185
 186         trace_xfs_symlink(dp, link_name);
 187
 188         if (XFS_FORCED_SHUTDOWN(mp))
 189                 return -EIO;
 190
 191         /*
 192          * Check component lengths of the target path name.
 193          */
 194         pathlen = strlen(target_path);
 195         if (pathlen >= XFS_SYMLINK_MAXLEN)      /* total string too long */
 196                 return -ENAMETOOLONG;
 197
 198         udqp = gdqp = NULL;
 199         prid = xfs_get_initial_prid(dp);
 200
 201         /*
 202          * Make sure that we have allocated dquot(s) on disk.
 203          */
 204         error = xfs_qm_vop_dqalloc(dp,
 205                         xfs_kuid_to_uid(current_fsuid()),
 206                         xfs_kgid_to_gid(current_fsgid()), prid,
 207                         XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
 208                         &udqp, &gdqp, &pdqp);
 209         if (error)
 210                 return error;
 211
 212         /*
 213          * The symlink will fit into the inode data fork?
 214          * There can't be any attributes so we get the whole variable part.
 215          */
 216         if (pathlen <= XFS_LITINO(mp, dp->i_d.di_version))
 217                 fs_blocks = 0;
 218         else
 219                 fs_blocks = xfs_symlink_blocks(mp, pathlen);
 220         resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
 221
 222         error = xfs_trans_alloc(mp, &M_RES(mp)->tr_symlink, resblks, 0, 0, &tp);
 223         if (error)
 224                 goto out_release_inode;
 225
 226         xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
 227         unlock_dp_on_error = true;
 228
 229         /*
 230          * Check whether the directory allows new symlinks or not.
 231          */
 232         if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) {
 233                 error = -EPERM;
 234                 goto out_trans_cancel;
 235         }
 236
 237         /*
 238          * Reserve disk quota : blocks and inode.
 239          */
 240         error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
 241                                                 pdqp, resblks, 1, 0);
 242         if (error)
 243                 goto out_trans_cancel;
 244
 245         /*
 246          * Initialize the bmap freelist prior to calling either
 247          * bmapi or the directory create code.
 248          */
 249         xfs_defer_init(&dfops, &first_block);
 250         tp->t_agfl_dfops = &dfops;
 251
 252         /*
 253          * Allocate an inode for the symlink.
 254          */
 255         error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0,
 256                                prid, &ip);
 257         if (error)
 258                 goto out_trans_cancel;
 259
 260         /*
 261          * Now we join the directory inode to the transaction.  We do not do it
 262          * earlier because xfs_dir_ialloc might commit the previous transaction
 263          * (and release all the locks).  An error from here on will result in
 264          * the transaction cancel unlocking dp so don't do it explicitly in the
 265          * error path.
 266          */
 267         xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
 268         unlock_dp_on_error = false;
 269
 270         /*
 271          * Also attach the dquot(s) to it, if applicable.
 272          */
 273         xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
 274
 275         if (resblks)
 276                 resblks -= XFS_IALLOC_SPACE_RES(mp);
 277         /*
 278          * If the symlink will fit into the inode, write it inline.
 279          */
 280         if (pathlen <= XFS_IFORK_DSIZE(ip)) {
 281                 xfs_init_local_fork(ip, XFS_DATA_FORK, target_path, pathlen);
 282
 283                 ip->i_d.di_size = pathlen;
 284                 ip->i_d.di_format = XFS_DINODE_FMT_LOCAL;
 285                 xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);
 286         } else {
 287                 int     offset;
 288
 289                 first_fsb = 0;
 290                 nmaps = XFS_SYMLINK_MAPS;
 291
 292                 error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks,
 293                                   XFS_BMAPI_METADATA, &first_block, resblks,
 294                                   mval, &nmaps, &dfops);
 295                 if (error)
 296                         goto out_bmap_cancel;
 297
 298                 if (resblks)
 299                         resblks -= fs_blocks;
 300                 ip->i_d.di_size = pathlen;
 301                 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 302
 303                 cur_chunk = target_path;
 304                 offset = 0;
 305                 for (n = 0; n < nmaps; n++) {
 306                         char    *buf;
 307
 308                         d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
 309                         byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
 310                         bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
 311                                                BTOBB(byte_cnt), 0);
 312                         if (!bp) {
 313                                 error = -ENOMEM;
 314                                 goto out_bmap_cancel;
 315                         }
 316                         bp->b_ops = &xfs_symlink_buf_ops;
 317
 318                         byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
 319                         byte_cnt = min(byte_cnt, pathlen);
 320
 321                         buf = bp->b_addr;
 322                         buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset,
 323                                                    byte_cnt, bp);
 324
 325                         memcpy(buf, cur_chunk, byte_cnt);
 326
 327                         cur_chunk += byte_cnt;
 328                         pathlen -= byte_cnt;
 329                         offset += byte_cnt;
 330
 331                         xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
 332                         xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
 333                                                         (char *)bp->b_addr);
 334                 }
 335                 ASSERT(pathlen == 0);
 336         }
 337
 338         /*
 339          * Create the directory entry for the symlink.
 340          */
 341         error = xfs_dir_createname(tp, dp, link_name, ip->i_ino,
 342                                         &first_block, &dfops, resblks);
 343         if (error)
 344                 goto out_bmap_cancel;
 345         xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 346         xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
 347
 348         /*
 349          * If this is a synchronous mount, make sure that the
 350          * symlink transaction goes to disk before returning to
 351          * the user.
 352          */
 353         if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
 354                 xfs_trans_set_sync(tp);
 355         }
 356
 357         error = xfs_defer_finish(&tp, &dfops);
 358         if (error)
 359                 goto out_bmap_cancel;
 360
 361         error = xfs_trans_commit(tp);
 362         if (error)
 363                 goto out_release_inode;
 364
 365         xfs_qm_dqrele(udqp);
 366         xfs_qm_dqrele(gdqp);
 367         xfs_qm_dqrele(pdqp);
 368
 369         *ipp = ip;
 370         return 0;
 371
 372 out_bmap_cancel:
 373         xfs_defer_cancel(&dfops);
 374 out_trans_cancel:
 375         xfs_trans_cancel(tp);
 376 out_release_inode:
 377         /*
 378          * Wait until after the current transaction is aborted to finish the
 379          * setup of the inode and release the inode.  This prevents recursive
 380          * transactions and deadlocks from xfs_inactive.
 381          */
 382         if (ip) {
 383                 xfs_finish_inode_setup(ip);
 384                 IRELE(ip);
 385         }
 386
 387         xfs_qm_dqrele(udqp);
 388         xfs_qm_dqrele(gdqp);
 389         xfs_qm_dqrele(pdqp);
 390
 391         if (unlock_dp_on_error)
 392                 xfs_iunlock(dp, XFS_ILOCK_EXCL);
 393         return error;
 394 }
 395
 396 /*
 397  * Free a symlink that has blocks associated with it.
 398  */
 399 STATIC int
 400 xfs_inactive_symlink_rmt(
 401         struct xfs_inode *ip)
 402 {
 403         xfs_buf_t       *bp;
 404         int             done;
 405         int             error;
 406         xfs_fsblock_t   first_block;
 407         struct xfs_defer_ops    dfops;
 408         int             i;
 409         xfs_mount_t     *mp;
 410         xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS];
 411         int             nmaps;
 412         int             size;
 413         xfs_trans_t     *tp;
 414
 415         mp = ip->i_mount;
 416         ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS);
 417         /*
 418          * We're freeing a symlink that has some
 419          * blocks allocated to it.  Free the
 420          * blocks here.  We know that we've got
 421          * either 1 or 2 extents and that we can
 422          * free them all in one bunmapi call.
 423          */
 424         ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2);
 425
 426         error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
 427         if (error)
 428                 return error;
 429
 430         xfs_ilock(ip, XFS_ILOCK_EXCL);
 431         xfs_trans_ijoin(tp, ip, 0);
 432
 433         /*
 434          * Lock the inode, fix the size, and join it to the transaction.
 435          * Hold it so in the normal path, we still have it locked for
 436          * the second transaction.  In the error paths we need it
 437          * held so the cancel won't rele it, see below.
 438          */
 439         size = (int)ip->i_d.di_size;
 440         ip->i_d.di_size = 0;
 441         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 442         /*
 443          * Find the block(s) so we can inval and unmap them.
 444          */
 445         done = 0;
 446         xfs_defer_init(&dfops, &first_block);
 447         nmaps = ARRAY_SIZE(mval);
 448         error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
 449                                 mval, &nmaps, 0);
 450         if (error)
 451                 goto error_trans_cancel;
 452         /*
 453          * Invalidate the block(s). No validation is done.
 454          */
 455         for (i = 0; i < nmaps; i++) {
 456                 bp = xfs_trans_get_buf(tp, mp->m_ddev_targp,
 457                         XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
 458                         XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0);
 459                 if (!bp) {
 460                         error = -ENOMEM;
 461                         goto error_bmap_cancel;
 462                 }
 463                 xfs_trans_binval(tp, bp);
 464         }
 465         /*
 466          * Unmap the dead block(s) to the dfops.
 467          */
 468         error = xfs_bunmapi(tp, ip, 0, size, 0, nmaps,
 469                             &first_block, &dfops, &done);
 470         if (error)
 471                 goto error_bmap_cancel;
 472         ASSERT(done);
 473         /*
 474          * Commit the first transaction.  This logs the EFI and the inode.
 475          */
 476         xfs_defer_ijoin(&dfops, ip);
 477         error = xfs_defer_finish(&tp, &dfops);
 478         if (error)
 479                 goto error_bmap_cancel;
 480
 481         /*
 482          * Commit the transaction containing extent freeing and EFDs.
 483          */
 484         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 485         error = xfs_trans_commit(tp);
 486         if (error) {
 487                 ASSERT(XFS_FORCED_SHUTDOWN(mp));
 488                 goto error_unlock;
 489         }
 490
 491         /*
 492          * Remove the memory for extent descriptions (just bookkeeping).
 493          */
 494         if (ip->i_df.if_bytes)
 495                 xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
 496         ASSERT(ip->i_df.if_bytes == 0);
 497
 498         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 499         return 0;
 500
 501 error_bmap_cancel:
 502         xfs_defer_cancel(&dfops);
 503 error_trans_cancel:
 504         xfs_trans_cancel(tp);
 505 error_unlock:
 506         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 507         return error;
 508 }
 509
 510 /*
 511  * xfs_inactive_symlink - free a symlink
 512  */
 513 int
 514 xfs_inactive_symlink(
 515         struct xfs_inode        *ip)
 516 {
 517         struct xfs_mount        *mp = ip->i_mount;
 518         int                     pathlen;
 519
 520         trace_xfs_inactive_symlink(ip);
 521
 522         if (XFS_FORCED_SHUTDOWN(mp))
 523                 return -EIO;
 524
 525         xfs_ilock(ip, XFS_ILOCK_EXCL);
 526
 527         /*
 528          * Zero length symlinks _can_ exist.
 529          */
 530         pathlen = (int)ip->i_d.di_size;
 531         if (!pathlen) {
 532                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 533                 return 0;
 534         }
 535
 536         if (pathlen < 0 || pathlen > XFS_SYMLINK_MAXLEN) {
 537                 xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
 538                          __func__, (unsigned long long)ip->i_ino, pathlen);
 539                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 540                 ASSERT(0);
 541                 return -EFSCORRUPTED;
 542         }
 543
 544         if (ip->i_df.if_flags & XFS_IFINLINE) {
 545                 if (ip->i_df.if_bytes > 0)
 546                         xfs_idata_realloc(ip, -(ip->i_df.if_bytes),
 547                                           XFS_DATA_FORK);
 548                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 549                 ASSERT(ip->i_df.if_bytes == 0);
 550                 return 0;
 551         }
 552
 553         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 554
 555         /* remove the remote symlink */
 556         return xfs_inactive_symlink_rmt(ip);
 557 }