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 ASSERT(pathlen > 0); 196 197 udqp = gdqp = NULL; 198 prid = xfs_get_initial_prid(dp); 199 200 /* 201 * Make sure that we have allocated dquot(s) on disk. 202 */ 203 error = xfs_qm_vop_dqalloc(dp, 204 xfs_kuid_to_uid(current_fsuid()), 205 xfs_kgid_to_gid(current_fsgid()), prid, 206 XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT, 207 &udqp, &gdqp, &pdqp); 208 if (error) 209 return error; 210 211 /* 212 * The symlink will fit into the inode data fork? 213 * There can't be any attributes so we get the whole variable part. 214 */ 215 if (pathlen <= XFS_LITINO(mp, dp->i_d.di_version)) 216 fs_blocks = 0; 217 else 218 fs_blocks = xfs_symlink_blocks(mp, pathlen); 219 resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks); 220 221 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_symlink, resblks, 0, 0, &tp); 222 if (error) 223 goto out_release_inode; 224 225 xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT); 226 unlock_dp_on_error = true; 227 228 /* 229 * Check whether the directory allows new symlinks or not. 230 */ 231 if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) { 232 error = -EPERM; 233 goto out_trans_cancel; 234 } 235 236 /* 237 * Reserve disk quota : blocks and inode. 238 */ 239 error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp, 240 pdqp, resblks, 1, 0); 241 if (error) 242 goto out_trans_cancel; 243 244 /* 245 * Allocate an inode for the symlink. 246 */ 247 error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0, 248 prid, &ip); 249 if (error) 250 goto out_trans_cancel; 251 252 /* 253 * Now we join the directory inode to the transaction. We do not do it 254 * earlier because xfs_dir_ialloc might commit the previous transaction 255 * (and release all the locks). An error from here on will result in 256 * the transaction cancel unlocking dp so don't do it explicitly in the 257 * error path. 258 */ 259 xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL); 260 unlock_dp_on_error = false; 261 262 /* 263 * Also attach the dquot(s) to it, if applicable. 264 */ 265 xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp); 266 267 if (resblks) 268 resblks -= XFS_IALLOC_SPACE_RES(mp); 269 /* 270 * If the symlink will fit into the inode, write it inline. 271 */ 272 if (pathlen <= XFS_IFORK_DSIZE(ip)) { 273 xfs_init_local_fork(ip, XFS_DATA_FORK, target_path, pathlen); 274 275 ip->i_d.di_size = pathlen; 276 ip->i_d.di_format = XFS_DINODE_FMT_LOCAL; 277 xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE); 278 } else { 279 int offset; 280 281 first_fsb = 0; 282 nmaps = XFS_SYMLINK_MAPS; 283 284 error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks, 285 XFS_BMAPI_METADATA, resblks, mval, &nmaps); 286 if (error) 287 goto out_trans_cancel; 288 289 if (resblks) 290 resblks -= fs_blocks; 291 ip->i_d.di_size = pathlen; 292 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); 293 294 cur_chunk = target_path; 295 offset = 0; 296 for (n = 0; n < nmaps; n++) { 297 char *buf; 298 299 d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock); 300 byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount); 301 bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d, 302 BTOBB(byte_cnt), 0); 303 if (!bp) { 304 error = -ENOMEM; 305 goto out_trans_cancel; 306 } 307 bp->b_ops = &xfs_symlink_buf_ops; 308 309 byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt); 310 byte_cnt = min(byte_cnt, pathlen); 311 312 buf = bp->b_addr; 313 buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset, 314 byte_cnt, bp); 315 316 memcpy(buf, cur_chunk, byte_cnt); 317 318 cur_chunk += byte_cnt; 319 pathlen -= byte_cnt; 320 offset += byte_cnt; 321 322 xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF); 323 xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) - 324 (char *)bp->b_addr); 325 } 326 ASSERT(pathlen == 0); 327 } 328 329 /* 330 * Create the directory entry for the symlink. 331 */ 332 error = xfs_dir_createname(tp, dp, link_name, ip->i_ino, resblks); 333 if (error) 334 goto out_trans_cancel; 335 xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG); 336 xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE); 337 338 /* 339 * If this is a synchronous mount, make sure that the 340 * symlink transaction goes to disk before returning to 341 * the user. 342 */ 343 if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) { 344 xfs_trans_set_sync(tp); 345 } 346 347 error = xfs_trans_commit(tp); 348 if (error) 349 goto out_release_inode; 350 351 xfs_qm_dqrele(udqp); 352 xfs_qm_dqrele(gdqp); 353 xfs_qm_dqrele(pdqp); 354 355 *ipp = ip; 356 return 0; 357 358 out_trans_cancel: 359 xfs_trans_cancel(tp); 360 out_release_inode: 361 /* 362 * Wait until after the current transaction is aborted to finish the 363 * setup of the inode and release the inode. This prevents recursive 364 * transactions and deadlocks from xfs_inactive. 365 */ 366 if (ip) { 367 xfs_finish_inode_setup(ip); 368 xfs_irele(ip); 369 } 370 371 xfs_qm_dqrele(udqp); 372 xfs_qm_dqrele(gdqp); 373 xfs_qm_dqrele(pdqp); 374 375 if (unlock_dp_on_error) 376 xfs_iunlock(dp, XFS_ILOCK_EXCL); 377 return error; 378 } 379 380 /* 381 * Free a symlink that has blocks associated with it. 382 * 383 * Note: zero length symlinks are not allowed to exist. When we set the size to 384 * zero, also change it to a regular file so that it does not get written to 385 * disk as a zero length symlink. The inode is on the unlinked list already, so 386 * userspace cannot find this inode anymore, so this change is not user visible 387 * but allows us to catch corrupt zero-length symlinks in the verifiers. 388 */ 389 STATIC int 390 xfs_inactive_symlink_rmt( 391 struct xfs_inode *ip) 392 { 393 xfs_buf_t *bp; 394 int done; 395 int error; 396 int i; 397 xfs_mount_t *mp; 398 xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS]; 399 int nmaps; 400 int size; 401 xfs_trans_t *tp; 402 403 mp = ip->i_mount; 404 ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS); 405 /* 406 * We're freeing a symlink that has some 407 * blocks allocated to it. Free the 408 * blocks here. We know that we've got 409 * either 1 or 2 extents and that we can 410 * free them all in one bunmapi call. 411 */ 412 ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2); 413 414 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp); 415 if (error) 416 return error; 417 418 xfs_ilock(ip, XFS_ILOCK_EXCL); 419 xfs_trans_ijoin(tp, ip, 0); 420 421 /* 422 * Lock the inode, fix the size, turn it into a regular file and join it 423 * to the transaction. Hold it so in the normal path, we still have it 424 * locked for the second transaction. In the error paths we need it 425 * held so the cancel won't rele it, see below. 426 */ 427 size = (int)ip->i_d.di_size; 428 ip->i_d.di_size = 0; 429 VFS_I(ip)->i_mode = (VFS_I(ip)->i_mode & ~S_IFMT) | S_IFREG; 430 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); 431 /* 432 * Find the block(s) so we can inval and unmap them. 433 */ 434 done = 0; 435 nmaps = ARRAY_SIZE(mval); 436 error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size), 437 mval, &nmaps, 0); 438 if (error) 439 goto error_trans_cancel; 440 /* 441 * Invalidate the block(s). No validation is done. 442 */ 443 for (i = 0; i < nmaps; i++) { 444 bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, 445 XFS_FSB_TO_DADDR(mp, mval[i].br_startblock), 446 XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0); 447 if (!bp) { 448 error = -ENOMEM; 449 goto error_trans_cancel; 450 } 451 xfs_trans_binval(tp, bp); 452 } 453 /* 454 * Unmap the dead block(s) to the dfops. 455 */ 456 error = xfs_bunmapi(tp, ip, 0, size, 0, nmaps, &done); 457 if (error) 458 goto error_trans_cancel; 459 ASSERT(done); 460 461 /* 462 * Commit the transaction. This first logs the EFI and the inode, then 463 * rolls and commits the transaction that frees the extents. 464 */ 465 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); 466 error = xfs_trans_commit(tp); 467 if (error) { 468 ASSERT(XFS_FORCED_SHUTDOWN(mp)); 469 goto error_unlock; 470 } 471 472 /* 473 * Remove the memory for extent descriptions (just bookkeeping). 474 */ 475 if (ip->i_df.if_bytes) 476 xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK); 477 ASSERT(ip->i_df.if_bytes == 0); 478 479 xfs_iunlock(ip, XFS_ILOCK_EXCL); 480 return 0; 481 482 error_trans_cancel: 483 xfs_trans_cancel(tp); 484 error_unlock: 485 xfs_iunlock(ip, XFS_ILOCK_EXCL); 486 return error; 487 } 488 489 /* 490 * xfs_inactive_symlink - free a symlink 491 */ 492 int 493 xfs_inactive_symlink( 494 struct xfs_inode *ip) 495 { 496 struct xfs_mount *mp = ip->i_mount; 497 int pathlen; 498 499 trace_xfs_inactive_symlink(ip); 500 501 if (XFS_FORCED_SHUTDOWN(mp)) 502 return -EIO; 503 504 xfs_ilock(ip, XFS_ILOCK_EXCL); 505 pathlen = (int)ip->i_d.di_size; 506 ASSERT(pathlen); 507 508 if (pathlen <= 0 || pathlen > XFS_SYMLINK_MAXLEN) { 509 xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)", 510 __func__, (unsigned long long)ip->i_ino, pathlen); 511 xfs_iunlock(ip, XFS_ILOCK_EXCL); 512 ASSERT(0); 513 return -EFSCORRUPTED; 514 } 515 516 /* 517 * Inline fork state gets removed by xfs_difree() so we have nothing to 518 * do here in that case. 519 */ 520 if (ip->i_df.if_flags & XFS_IFINLINE) { 521 xfs_iunlock(ip, XFS_ILOCK_EXCL); 522 return 0; 523 } 524 525 xfs_iunlock(ip, XFS_ILOCK_EXCL); 526 527 /* remove the remote symlink */ 528 return xfs_inactive_symlink_rmt(ip); 529 } 530