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_dir2.h"
  16 #include "xfs_inode.h"
  17 #include "xfs_bmap.h"
  18 #include "xfs_bmap_btree.h"
  19 #include "xfs_quota.h"
  20 #include "xfs_symlink.h"
  21 #include "xfs_trans_space.h"
  22 #include "xfs_trace.h"
  23 #include "xfs_trans.h"
  24
  25 /* ----- Kernel only functions below ----- */
  26 int
  27 xfs_readlink_bmap_ilocked(
  28         struct xfs_inode        *ip,
  29         char                    *link)
  30 {
  31         struct xfs_mount        *mp = ip->i_mount;
  32         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
  33         struct xfs_buf          *bp;
  34         xfs_daddr_t             d;
  35         char                    *cur_chunk;
  36         int                     pathlen = ip->i_d.di_size;
  37         int                     nmaps = XFS_SYMLINK_MAPS;
  38         int                     byte_cnt;
  39         int                     n;
  40         int                     error = 0;
  41         int                     fsblocks = 0;
  42         int                     offset;
  43
  44         ASSERT(xfs_isilocked(ip, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
  45
  46         fsblocks = xfs_symlink_blocks(mp, pathlen);
  47         error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0);
  48         if (error)
  49                 goto out;
  50
  51         offset = 0;
  52         for (n = 0; n < nmaps; n++) {
  53                 d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
  54                 byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
  55
  56                 error = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
  57                                 &bp, &xfs_symlink_buf_ops);
  58                 if (error)
  59                         return error;
  60                 byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
  61                 if (pathlen < byte_cnt)
  62                         byte_cnt = pathlen;
  63
  64                 cur_chunk = bp->b_addr;
  65                 if (xfs_sb_version_hascrc(&mp->m_sb)) {
  66                         if (!xfs_symlink_hdr_ok(ip->i_ino, offset,
  67                                                         byte_cnt, bp)) {
  68                                 error = -EFSCORRUPTED;
  69                                 xfs_alert(mp,
  70 "symlink header does not match required off/len/owner (0x%x/Ox%x,0x%llx)",
  71                                         offset, byte_cnt, ip->i_ino);
  72                                 xfs_buf_relse(bp);
  73                                 goto out;
  74
  75                         }
  76
  77                         cur_chunk += sizeof(struct xfs_dsymlink_hdr);
  78                 }
  79
  80                 memcpy(link + offset, cur_chunk, byte_cnt);
  81
  82                 pathlen -= byte_cnt;
  83                 offset += byte_cnt;
  84
  85                 xfs_buf_relse(bp);
  86         }
  87         ASSERT(pathlen == 0);
  88
  89         link[ip->i_d.di_size] = '\0';
  90         error = 0;
  91
  92  out:
  93         return error;
  94 }
  95
  96 int
  97 xfs_readlink(
  98         struct xfs_inode *ip,
  99         char            *link)
 100 {
 101         struct xfs_mount *mp = ip->i_mount;
 102         xfs_fsize_t     pathlen;
 103         int             error = 0;
 104
 105         trace_xfs_readlink(ip);
 106
 107         ASSERT(!(ip->i_df.if_flags & XFS_IFINLINE));
 108
 109         if (XFS_FORCED_SHUTDOWN(mp))
 110                 return -EIO;
 111
 112         xfs_ilock(ip, XFS_ILOCK_SHARED);
 113
 114         pathlen = ip->i_d.di_size;
 115         if (!pathlen)
 116                 goto out;
 117
 118         if (pathlen < 0 || pathlen > XFS_SYMLINK_MAXLEN) {
 119                 xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)",
 120                          __func__, (unsigned long long) ip->i_ino,
 121                          (long long) pathlen);
 122                 ASSERT(0);
 123                 error = -EFSCORRUPTED;
 124                 goto out;
 125         }
 126
 127
 128         error = xfs_readlink_bmap_ilocked(ip, link);
 129
 130  out:
 131         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 132         return error;
 133 }
 134
 135 int
 136 xfs_symlink(
 137         struct xfs_inode        *dp,
 138         struct xfs_name         *link_name,
 139         const char              *target_path,
 140         umode_t                 mode,
 141         struct xfs_inode        **ipp)
 142 {
 143         struct xfs_mount        *mp = dp->i_mount;
 144         struct xfs_trans        *tp = NULL;
 145         struct xfs_inode        *ip = NULL;
 146         int                     error = 0;
 147         int                     pathlen;
 148         bool                    unlock_dp_on_error = false;
 149         xfs_fileoff_t           first_fsb;
 150         xfs_filblks_t           fs_blocks;
 151         int                     nmaps;
 152         struct xfs_bmbt_irec    mval[XFS_SYMLINK_MAPS];
 153         xfs_daddr_t             d;
 154         const char              *cur_chunk;
 155         int                     byte_cnt;
 156         int                     n;
 157         xfs_buf_t               *bp;
 158         prid_t                  prid;
 159         struct xfs_dquot        *udqp = NULL;
 160         struct xfs_dquot        *gdqp = NULL;
 161         struct xfs_dquot        *pdqp = NULL;
 162         uint                    resblks;
 163
 164         *ipp = NULL;
 165
 166         trace_xfs_symlink(dp, link_name);
 167
 168         if (XFS_FORCED_SHUTDOWN(mp))
 169                 return -EIO;
 170
 171         /*
 172          * Check component lengths of the target path name.
 173          */
 174         pathlen = strlen(target_path);
 175         if (pathlen >= XFS_SYMLINK_MAXLEN)      /* total string too long */
 176                 return -ENAMETOOLONG;
 177         ASSERT(pathlen > 0);
 178
 179         prid = xfs_get_initial_prid(dp);
 180
 181         /*
 182          * Make sure that we have allocated dquot(s) on disk.
 183          */
 184         error = xfs_qm_vop_dqalloc(dp, current_fsuid(), current_fsgid(), prid,
 185                         XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
 186                         &udqp, &gdqp, &pdqp);
 187         if (error)
 188                 return error;
 189
 190         /*
 191          * The symlink will fit into the inode data fork?
 192          * There can't be any attributes so we get the whole variable part.
 193          */
 194         if (pathlen <= XFS_LITINO(mp))
 195                 fs_blocks = 0;
 196         else
 197                 fs_blocks = xfs_symlink_blocks(mp, pathlen);
 198         resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
 199
 200         error = xfs_trans_alloc(mp, &M_RES(mp)->tr_symlink, resblks, 0, 0, &tp);
 201         if (error)
 202                 goto out_release_inode;
 203
 204         xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
 205         unlock_dp_on_error = true;
 206
 207         /*
 208          * Check whether the directory allows new symlinks or not.
 209          */
 210         if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) {
 211                 error = -EPERM;
 212                 goto out_trans_cancel;
 213         }
 214
 215         /*
 216          * Reserve disk quota : blocks and inode.
 217          */
 218         error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
 219                                                 pdqp, resblks, 1, 0);
 220         if (error)
 221                 goto out_trans_cancel;
 222
 223         /*
 224          * Allocate an inode for the symlink.
 225          */
 226         error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0,
 227                                prid, &ip);
 228         if (error)
 229                 goto out_trans_cancel;
 230
 231         /*
 232          * Now we join the directory inode to the transaction.  We do not do it
 233          * earlier because xfs_dir_ialloc might commit the previous transaction
 234          * (and release all the locks).  An error from here on will result in
 235          * the transaction cancel unlocking dp so don't do it explicitly in the
 236          * error path.
 237          */
 238         xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
 239         unlock_dp_on_error = false;
 240
 241         /*
 242          * Also attach the dquot(s) to it, if applicable.
 243          */
 244         xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
 245
 246         if (resblks)
 247                 resblks -= XFS_IALLOC_SPACE_RES(mp);
 248         /*
 249          * If the symlink will fit into the inode, write it inline.
 250          */
 251         if (pathlen <= XFS_IFORK_DSIZE(ip)) {
 252                 xfs_init_local_fork(ip, XFS_DATA_FORK, target_path, pathlen);
 253
 254                 ip->i_d.di_size = pathlen;
 255                 ip->i_d.di_format = XFS_DINODE_FMT_LOCAL;
 256                 xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);
 257         } else {
 258                 int     offset;
 259
 260                 first_fsb = 0;
 261                 nmaps = XFS_SYMLINK_MAPS;
 262
 263                 error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks,
 264                                   XFS_BMAPI_METADATA, resblks, mval, &nmaps);
 265                 if (error)
 266                         goto out_trans_cancel;
 267
 268                 if (resblks)
 269                         resblks -= fs_blocks;
 270                 ip->i_d.di_size = pathlen;
 271                 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 272
 273                 cur_chunk = target_path;
 274                 offset = 0;
 275                 for (n = 0; n < nmaps; n++) {
 276                         char    *buf;
 277
 278                         d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
 279                         byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
 280                         error = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
 281                                                BTOBB(byte_cnt), 0, &bp);
 282                         if (error)
 283                                 goto out_trans_cancel;
 284                         bp->b_ops = &xfs_symlink_buf_ops;
 285
 286                         byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
 287                         byte_cnt = min(byte_cnt, pathlen);
 288
 289                         buf = bp->b_addr;
 290                         buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset,
 291                                                    byte_cnt, bp);
 292
 293                         memcpy(buf, cur_chunk, byte_cnt);
 294
 295                         cur_chunk += byte_cnt;
 296                         pathlen -= byte_cnt;
 297                         offset += byte_cnt;
 298
 299                         xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
 300                         xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
 301                                                         (char *)bp->b_addr);
 302                 }
 303                 ASSERT(pathlen == 0);
 304         }
 305
 306         /*
 307          * Create the directory entry for the symlink.
 308          */
 309         error = xfs_dir_createname(tp, dp, link_name, ip->i_ino, resblks);
 310         if (error)
 311                 goto out_trans_cancel;
 312         xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 313         xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
 314
 315         /*
 316          * If this is a synchronous mount, make sure that the
 317          * symlink transaction goes to disk before returning to
 318          * the user.
 319          */
 320         if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
 321                 xfs_trans_set_sync(tp);
 322         }
 323
 324         error = xfs_trans_commit(tp);
 325         if (error)
 326                 goto out_release_inode;
 327
 328         xfs_qm_dqrele(udqp);
 329         xfs_qm_dqrele(gdqp);
 330         xfs_qm_dqrele(pdqp);
 331
 332         *ipp = ip;
 333         return 0;
 334
 335 out_trans_cancel:
 336         xfs_trans_cancel(tp);
 337 out_release_inode:
 338         /*
 339          * Wait until after the current transaction is aborted to finish the
 340          * setup of the inode and release the inode.  This prevents recursive
 341          * transactions and deadlocks from xfs_inactive.
 342          */
 343         if (ip) {
 344                 xfs_finish_inode_setup(ip);
 345                 xfs_irele(ip);
 346         }
 347
 348         xfs_qm_dqrele(udqp);
 349         xfs_qm_dqrele(gdqp);
 350         xfs_qm_dqrele(pdqp);
 351
 352         if (unlock_dp_on_error)
 353                 xfs_iunlock(dp, XFS_ILOCK_EXCL);
 354         return error;
 355 }
 356
 357 /*
 358  * Free a symlink that has blocks associated with it.
 359  *
 360  * Note: zero length symlinks are not allowed to exist. When we set the size to
 361  * zero, also change it to a regular file so that it does not get written to
 362  * disk as a zero length symlink. The inode is on the unlinked list already, so
 363  * userspace cannot find this inode anymore, so this change is not user visible
 364  * but allows us to catch corrupt zero-length symlinks in the verifiers.
 365  */
 366 STATIC int
 367 xfs_inactive_symlink_rmt(
 368         struct xfs_inode *ip)
 369 {
 370         xfs_buf_t       *bp;
 371         int             done;
 372         int             error;
 373         int             i;
 374         xfs_mount_t     *mp;
 375         xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS];
 376         int             nmaps;
 377         int             size;
 378         xfs_trans_t     *tp;
 379
 380         mp = ip->i_mount;
 381         ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS);
 382         /*
 383          * We're freeing a symlink that has some
 384          * blocks allocated to it.  Free the
 385          * blocks here.  We know that we've got
 386          * either 1 or 2 extents and that we can
 387          * free them all in one bunmapi call.
 388          */
 389         ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2);
 390
 391         error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
 392         if (error)
 393                 return error;
 394
 395         xfs_ilock(ip, XFS_ILOCK_EXCL);
 396         xfs_trans_ijoin(tp, ip, 0);
 397
 398         /*
 399          * Lock the inode, fix the size, turn it into a regular file and join it
 400          * to the transaction.  Hold it so in the normal path, we still have it
 401          * locked for the second transaction.  In the error paths we need it
 402          * held so the cancel won't rele it, see below.
 403          */
 404         size = (int)ip->i_d.di_size;
 405         ip->i_d.di_size = 0;
 406         VFS_I(ip)->i_mode = (VFS_I(ip)->i_mode & ~S_IFMT) | S_IFREG;
 407         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 408         /*
 409          * Find the block(s) so we can inval and unmap them.
 410          */
 411         done = 0;
 412         nmaps = ARRAY_SIZE(mval);
 413         error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
 414                                 mval, &nmaps, 0);
 415         if (error)
 416                 goto error_trans_cancel;
 417         /*
 418          * Invalidate the block(s). No validation is done.
 419          */
 420         for (i = 0; i < nmaps; i++) {
 421                 error = xfs_trans_get_buf(tp, mp->m_ddev_targp,
 422                                 XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
 423                                 XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0,
 424                                 &bp);
 425                 if (error)
 426                         goto error_trans_cancel;
 427                 xfs_trans_binval(tp, bp);
 428         }
 429         /*
 430          * Unmap the dead block(s) to the dfops.
 431          */
 432         error = xfs_bunmapi(tp, ip, 0, size, 0, nmaps, &done);
 433         if (error)
 434                 goto error_trans_cancel;
 435         ASSERT(done);
 436
 437         /*
 438          * Commit the transaction. This first logs the EFI and the inode, then
 439          * rolls and commits the transaction that frees the extents.
 440          */
 441         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 442         error = xfs_trans_commit(tp);
 443         if (error) {
 444                 ASSERT(XFS_FORCED_SHUTDOWN(mp));
 445                 goto error_unlock;
 446         }
 447
 448         /*
 449          * Remove the memory for extent descriptions (just bookkeeping).
 450          */
 451         if (ip->i_df.if_bytes)
 452                 xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
 453         ASSERT(ip->i_df.if_bytes == 0);
 454
 455         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 456         return 0;
 457
 458 error_trans_cancel:
 459         xfs_trans_cancel(tp);
 460 error_unlock:
 461         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 462         return error;
 463 }
 464
 465 /*
 466  * xfs_inactive_symlink - free a symlink
 467  */
 468 int
 469 xfs_inactive_symlink(
 470         struct xfs_inode        *ip)
 471 {
 472         struct xfs_mount        *mp = ip->i_mount;
 473         int                     pathlen;
 474
 475         trace_xfs_inactive_symlink(ip);
 476
 477         if (XFS_FORCED_SHUTDOWN(mp))
 478                 return -EIO;
 479
 480         xfs_ilock(ip, XFS_ILOCK_EXCL);
 481         pathlen = (int)ip->i_d.di_size;
 482         ASSERT(pathlen);
 483
 484         if (pathlen <= 0 || pathlen > XFS_SYMLINK_MAXLEN) {
 485                 xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
 486                          __func__, (unsigned long long)ip->i_ino, pathlen);
 487                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 488                 ASSERT(0);
 489                 return -EFSCORRUPTED;
 490         }
 491
 492         /*
 493          * Inline fork state gets removed by xfs_difree() so we have nothing to
 494          * do here in that case.
 495          */
 496         if (ip->i_df.if_flags & XFS_IFINLINE) {
 497                 xfs_iunlock(ip, XFS_ILOCK_EXCL);
 498                 return 0;
 499         }
 500
 501         xfs_iunlock(ip, XFS_ILOCK_EXCL);
 502
 503         /* remove the remote symlink */
 504         return xfs_inactive_symlink_rmt(ip);
 505 }