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         bool                    unlock_dp_on_error = false;
 167         xfs_fileoff_t           first_fsb;
 168         xfs_filblks_t           fs_blocks;
 169         int                     nmaps;
 170         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
 171         xfs_daddr_t             d;
 172         const char              *cur_chunk;
 173         int                     byte_cnt;
 174         int                     n;
 175         xfs_buf_t               *bp;
 176         prid_t                  prid;
 177         struct xfs_dquot        *udqp = NULL;
 178         struct xfs_dquot        *gdqp = NULL;
 179         struct xfs_dquot        *pdqp = NULL;
 180         uint                    resblks;
 181
 182         *ipp = NULL;
 183
 184         trace_xfs_symlink(dp, link_name);
 185
 186         if (XFS_FORCED_SHUTDOWN(mp))
 187                 return -EIO;
 188
 189         /*
 190          * Check component lengths of the target path name.
 191          */
 192         pathlen = strlen(target_path);
 193         if (pathlen >= XFS_SYMLINK_MAXLEN)      /* total string too long */
 194                 return -ENAMETOOLONG;
 195
 196         udqp = gdqp = NULL;
 197         prid = xfs_get_initial_prid(dp);
 198
 199         /*
 200          * Make sure that we have allocated dquot(s) on disk.
 201          */
 202         error = xfs_qm_vop_dqalloc(dp,
 203                         xfs_kuid_to_uid(current_fsuid()),
 204                         xfs_kgid_to_gid(current_fsgid()), prid,
 205                         XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
 206                         &udqp, &gdqp, &pdqp);
 207         if (error)
 208                 return error;
 209
 210         /*
 211          * The symlink will fit into the inode data fork?
 212          * There can't be any attributes so we get the whole variable part.
 213          */
 214         if (pathlen <= XFS_LITINO(mp, dp->i_d.di_version))
 215                 fs_blocks = 0;
 216         else
 217                 fs_blocks = xfs_symlink_blocks(mp, pathlen);
 218         resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
 219
 220         error = xfs_trans_alloc(mp, &M_RES(mp)->tr_symlink, resblks, 0, 0, &tp);
 221         if (error)
 222                 goto out_release_inode;
 223
 224         xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
 225         unlock_dp_on_error = true;
 226
 227         /*
 228          * Check whether the directory allows new symlinks or not.
 229          */
 230         if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) {
 231                 error = -EPERM;
 232                 goto out_trans_cancel;
 233         }
 234
 235         /*
 236          * Reserve disk quota : blocks and inode.
 237          */
 238         error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
 239                                                 pdqp, resblks, 1, 0);
 240         if (error)
 241                 goto out_trans_cancel;
 242
 243         /*
 244          * Allocate an inode for the symlink.
 245          */
 246         error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0,
 247                                prid, &ip);
 248         if (error)
 249                 goto out_trans_cancel;
 250
 251         /*
 252          * Now we join the directory inode to the transaction.  We do not do it
 253          * earlier because xfs_dir_ialloc might commit the previous transaction
 254          * (and release all the locks).  An error from here on will result in
 255          * the transaction cancel unlocking dp so don't do it explicitly in the
 256          * error path.
 257          */
 258         xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
 259         unlock_dp_on_error = false;
 260
 261         /*
 262          * Also attach the dquot(s) to it, if applicable.
 263          */
 264         xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
 265
 266         if (resblks)
 267                 resblks -= XFS_IALLOC_SPACE_RES(mp);
 268         /*
 269          * If the symlink will fit into the inode, write it inline.
 270          */
 271         if (pathlen <= XFS_IFORK_DSIZE(ip)) {
 272                 xfs_init_local_fork(ip, XFS_DATA_FORK, target_path, pathlen);
 273
 274                 ip->i_d.di_size = pathlen;
 275                 ip->i_d.di_format = XFS_DINODE_FMT_LOCAL;
 276                 xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);
 277         } else {
 278                 int     offset;
 279
 280                 first_fsb = 0;
 281                 nmaps = XFS_SYMLINK_MAPS;
 282
 283                 error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks,
 284                                   XFS_BMAPI_METADATA, resblks, mval, &nmaps);
 285                 if (error)
 286                         goto out_trans_cancel;
 287
 288                 if (resblks)
 289                         resblks -= fs_blocks;
 290                 ip->i_d.di_size = pathlen;
 291                 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 292
 293                 cur_chunk = target_path;
 294                 offset = 0;
 295                 for (n = 0; n < nmaps; n++) {
 296                         char    *buf;
 297
 298                         d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
 299                         byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
 300                         bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
 301                                                BTOBB(byte_cnt), 0);
 302                         if (!bp) {
 303                                 error = -ENOMEM;
 304                                 goto out_trans_cancel;
 305                         }
 306                         bp->b_ops = &xfs_symlink_buf_ops;
 307
 308                         byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
 309                         byte_cnt = min(byte_cnt, pathlen);
 310
 311                         buf = bp->b_addr;
 312                         buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset,
 313                                                    byte_cnt, bp);
 314
 315                         memcpy(buf, cur_chunk, byte_cnt);
 316
 317                         cur_chunk += byte_cnt;
 318                         pathlen -= byte_cnt;
 319                         offset += byte_cnt;
 320
 321                         xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
 322                         xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
 323                                                         (char *)bp->b_addr);
 324                 }
 325                 ASSERT(pathlen == 0);
 326         }
 327
 328         /*
 329          * Create the directory entry for the symlink.
 330          */
 331         error = xfs_dir_createname(tp, dp, link_name, ip->i_ino, resblks);
 332         if (error)
 333                 goto out_trans_cancel;
 334         xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 335         xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
 336
 337         /*
 338          * If this is a synchronous mount, make sure that the
 339          * symlink transaction goes to disk before returning to
 340          * the user.
 341          */
 342         if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
 343                 xfs_trans_set_sync(tp);
 344         }
 345
 346         error = xfs_trans_commit(tp);
 347         if (error)
 348                 goto out_release_inode;
 349
 350         xfs_qm_dqrele(udqp);
 351         xfs_qm_dqrele(gdqp);
 352         xfs_qm_dqrele(pdqp);
 353
 354         *ipp = ip;
 355         return 0;
 356
 357 out_trans_cancel:
 358         xfs_trans_cancel(tp);
 359 out_release_inode:
 360         /*
 361          * Wait until after the current transaction is aborted to finish the
 362          * setup of the inode and release the inode.  This prevents recursive
 363          * transactions and deadlocks from xfs_inactive.
 364          */
 365         if (ip) {
 366                 xfs_finish_inode_setup(ip);
 367                 xfs_irele(ip);
 368         }
 369
 370         xfs_qm_dqrele(udqp);
 371         xfs_qm_dqrele(gdqp);
 372         xfs_qm_dqrele(pdqp);
 373
 374         if (unlock_dp_on_error)
 375                 xfs_iunlock(dp, XFS_ILOCK_EXCL);
 376         return error;
 377 }
 378
 379 /*
 380  * Free a symlink that has blocks associated with it.
 381  */
 382 STATIC int
 383 xfs_inactive_symlink_rmt(
 384         struct xfs_inode *ip)
 385 {
 386         xfs_buf_t       *bp;
 387         int             done;
 388         int             error;
 389         int             i;
 390         xfs_mount_t     *mp;
 391         xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS];
 392         int             nmaps;
 393         int             size;
 394         xfs_trans_t     *tp;
 395
 396         mp = ip->i_mount;
 397         ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS);
 398         /*
 399          * We're freeing a symlink that has some
 400          * blocks allocated to it.  Free the
 401          * blocks here.  We know that we've got
 402          * either 1 or 2 extents and that we can
 403          * free them all in one bunmapi call.
 404          */
 405         ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2);
 406
 407         error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
 408         if (error)
 409                 return error;
 410
 411         xfs_ilock(ip, XFS_ILOCK_EXCL);
 412         xfs_trans_ijoin(tp, ip, 0);
 413
 414         /*
 415          * Lock the inode, fix the size, and join it to the transaction.
 416          * Hold it so in the normal path, we still have it locked for
 417          * the second transaction.  In the error paths we need it
 418          * held so the cancel won't rele it, see below.
 419          */
 420         size = (int)ip->i_d.di_size;
 421         ip->i_d.di_size = 0;
 422         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 423         /*
 424          * Find the block(s) so we can inval and unmap them.
 425          */
 426         done = 0;
 427         nmaps = ARRAY_SIZE(mval);
 428         error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
 429                                 mval, &nmaps, 0);
 430         if (error)
 431                 goto error_trans_cancel;
 432         /*
 433          * Invalidate the block(s). No validation is done.
 434          */
 435         for (i = 0; i < nmaps; i++) {
 436                 bp = xfs_trans_get_buf(tp, mp->m_ddev_targp,
 437                         XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
 438                         XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0);
 439                 if (!bp) {
 440                         error = -ENOMEM;
 441                         goto error_trans_cancel;
 442                 }
 443                 xfs_trans_binval(tp, bp);
 444         }
 445         /*
 446          * Unmap the dead block(s) to the dfops.
 447          */
 448         error = xfs_bunmapi(tp, ip, 0, size, 0, nmaps, &done);
 449         if (error)
 450                 goto error_trans_cancel;
 451         ASSERT(done);
 452
 453         /*
 454          * Commit the transaction. This first logs the EFI and the inode, then
 455          * rolls and commits the transaction that frees the extents.
 456          */
 457         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 458         error = xfs_trans_commit(tp);
 459         if (error) {
 460                 ASSERT(XFS_FORCED_SHUTDOWN(mp));
 461                 goto error_unlock;
 462         }
 463
 464         /*
 465          * Remove the memory for extent descriptions (just bookkeeping).
 466          */
 467         if (ip->i_df.if_bytes)
 468                 xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
 469         ASSERT(ip->i_df.if_bytes == 0);
 470
 471         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 472         return 0;
 473
 474 error_trans_cancel:
 475         xfs_trans_cancel(tp);
 476 error_unlock:
 477         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 478         return error;
 479 }
 480
 481 /*
 482  * xfs_inactive_symlink - free a symlink
 483  */
 484 int
 485 xfs_inactive_symlink(
 486         struct xfs_inode        *ip)
 487 {
 488         struct xfs_mount        *mp = ip->i_mount;
 489         int                     pathlen;
 490
 491         trace_xfs_inactive_symlink(ip);
 492
 493         if (XFS_FORCED_SHUTDOWN(mp))
 494                 return -EIO;
 495
 496         xfs_ilock(ip, XFS_ILOCK_EXCL);
 497
 498         /*
 499          * Zero length symlinks _can_ exist.
 500          */
 501         pathlen = (int)ip->i_d.di_size;
 502         if (!pathlen) {
 503                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 504                 return 0;
 505         }
 506
 507         if (pathlen < 0 || pathlen > XFS_SYMLINK_MAXLEN) {
 508                 xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
 509                          __func__, (unsigned long long)ip->i_ino, pathlen);
 510                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 511                 ASSERT(0);
 512                 return -EFSCORRUPTED;
 513         }
 514
 515         if (ip->i_df.if_flags & XFS_IFINLINE) {
 516                 if (ip->i_df.if_bytes > 0)
 517                         xfs_idata_realloc(ip, -(ip->i_df.if_bytes),
 518                                           XFS_DATA_FORK);
 519                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 520                 ASSERT(ip->i_df.if_bytes == 0);
 521                 return 0;
 522         }
 523
 524         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 525
 526         /* remove the remote symlink */
 527         return xfs_inactive_symlink_rmt(ip);
 528 }