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 bp = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0, 57 &xfs_symlink_buf_ops); 58 if (!bp) 59 return -ENOMEM; 60 error = bp->b_error; 61 if (error) { 62 xfs_buf_ioerror_alert(bp, __func__); 63 xfs_buf_relse(bp); 64 65 /* bad CRC means corrupted metadata */ 66 if (error == -EFSBADCRC) 67 error = -EFSCORRUPTED; 68 goto out; 69 } 70 byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt); 71 if (pathlen < byte_cnt) 72 byte_cnt = pathlen; 73 74 cur_chunk = bp->b_addr; 75 if (xfs_sb_version_hascrc(&mp->m_sb)) { 76 if (!xfs_symlink_hdr_ok(ip->i_ino, offset, 77 byte_cnt, bp)) { 78 error = -EFSCORRUPTED; 79 xfs_alert(mp, 80 "symlink header does not match required off/len/owner (0x%x/Ox%x,0x%llx)", 81 offset, byte_cnt, ip->i_ino); 82 xfs_buf_relse(bp); 83 goto out; 84 85 } 86 87 cur_chunk += sizeof(struct xfs_dsymlink_hdr); 88 } 89 90 memcpy(link + offset, cur_chunk, byte_cnt); 91 92 pathlen -= byte_cnt; 93 offset += byte_cnt; 94 95 xfs_buf_relse(bp); 96 } 97 ASSERT(pathlen == 0); 98 99 link[ip->i_d.di_size] = '\0'; 100 error = 0; 101 102 out: 103 return error; 104 } 105 106 int 107 xfs_readlink( 108 struct xfs_inode *ip, 109 char *link) 110 { 111 struct xfs_mount *mp = ip->i_mount; 112 xfs_fsize_t pathlen; 113 int error = 0; 114 115 trace_xfs_readlink(ip); 116 117 ASSERT(!(ip->i_df.if_flags & XFS_IFINLINE)); 118 119 if (XFS_FORCED_SHUTDOWN(mp)) 120 return -EIO; 121 122 xfs_ilock(ip, XFS_ILOCK_SHARED); 123 124 pathlen = ip->i_d.di_size; 125 if (!pathlen) 126 goto out; 127 128 if (pathlen < 0 || pathlen > XFS_SYMLINK_MAXLEN) { 129 xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)", 130 __func__, (unsigned long long) ip->i_ino, 131 (long long) pathlen); 132 ASSERT(0); 133 error = -EFSCORRUPTED; 134 goto out; 135 } 136 137 138 error = xfs_readlink_bmap_ilocked(ip, link); 139 140 out: 141 xfs_iunlock(ip, XFS_ILOCK_SHARED); 142 return error; 143 } 144 145 int 146 xfs_symlink( 147 struct xfs_inode *dp, 148 struct xfs_name *link_name, 149 const char *target_path, 150 umode_t mode, 151 struct xfs_inode **ipp) 152 { 153 struct xfs_mount *mp = dp->i_mount; 154 struct xfs_trans *tp = NULL; 155 struct xfs_inode *ip = NULL; 156 int error = 0; 157 int pathlen; 158 bool unlock_dp_on_error = false; 159 xfs_fileoff_t first_fsb; 160 xfs_filblks_t fs_blocks; 161 int nmaps; 162 struct xfs_bmbt_irec mval[XFS_SYMLINK_MAPS]; 163 xfs_daddr_t d; 164 const char *cur_chunk; 165 int byte_cnt; 166 int n; 167 xfs_buf_t *bp; 168 prid_t prid; 169 struct xfs_dquot *udqp = NULL; 170 struct xfs_dquot *gdqp = NULL; 171 struct xfs_dquot *pdqp = NULL; 172 uint resblks; 173 174 *ipp = NULL; 175 176 trace_xfs_symlink(dp, link_name); 177 178 if (XFS_FORCED_SHUTDOWN(mp)) 179 return -EIO; 180 181 /* 182 * Check component lengths of the target path name. 183 */ 184 pathlen = strlen(target_path); 185 if (pathlen >= XFS_SYMLINK_MAXLEN) /* total string too long */ 186 return -ENAMETOOLONG; 187 ASSERT(pathlen > 0); 188 189 udqp = gdqp = NULL; 190 prid = xfs_get_initial_prid(dp); 191 192 /* 193 * Make sure that we have allocated dquot(s) on disk. 194 */ 195 error = xfs_qm_vop_dqalloc(dp, 196 xfs_kuid_to_uid(current_fsuid()), 197 xfs_kgid_to_gid(current_fsgid()), prid, 198 XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT, 199 &udqp, &gdqp, &pdqp); 200 if (error) 201 return error; 202 203 /* 204 * The symlink will fit into the inode data fork? 205 * There can't be any attributes so we get the whole variable part. 206 */ 207 if (pathlen <= XFS_LITINO(mp, dp->i_d.di_version)) 208 fs_blocks = 0; 209 else 210 fs_blocks = xfs_symlink_blocks(mp, pathlen); 211 resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks); 212 213 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_symlink, resblks, 0, 0, &tp); 214 if (error) 215 goto out_release_inode; 216 217 xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT); 218 unlock_dp_on_error = true; 219 220 /* 221 * Check whether the directory allows new symlinks or not. 222 */ 223 if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) { 224 error = -EPERM; 225 goto out_trans_cancel; 226 } 227 228 /* 229 * Reserve disk quota : blocks and inode. 230 */ 231 error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp, 232 pdqp, resblks, 1, 0); 233 if (error) 234 goto out_trans_cancel; 235 236 /* 237 * Allocate an inode for the symlink. 238 */ 239 error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0, 240 prid, &ip); 241 if (error) 242 goto out_trans_cancel; 243 244 /* 245 * Now we join the directory inode to the transaction. We do not do it 246 * earlier because xfs_dir_ialloc might commit the previous transaction 247 * (and release all the locks). An error from here on will result in 248 * the transaction cancel unlocking dp so don't do it explicitly in the 249 * error path. 250 */ 251 xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL); 252 unlock_dp_on_error = false; 253 254 /* 255 * Also attach the dquot(s) to it, if applicable. 256 */ 257 xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp); 258 259 if (resblks) 260 resblks -= XFS_IALLOC_SPACE_RES(mp); 261 /* 262 * If the symlink will fit into the inode, write it inline. 263 */ 264 if (pathlen <= XFS_IFORK_DSIZE(ip)) { 265 xfs_init_local_fork(ip, XFS_DATA_FORK, target_path, pathlen); 266 267 ip->i_d.di_size = pathlen; 268 ip->i_d.di_format = XFS_DINODE_FMT_LOCAL; 269 xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE); 270 } else { 271 int offset; 272 273 first_fsb = 0; 274 nmaps = XFS_SYMLINK_MAPS; 275 276 error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks, 277 XFS_BMAPI_METADATA, resblks, mval, &nmaps); 278 if (error) 279 goto out_trans_cancel; 280 281 if (resblks) 282 resblks -= fs_blocks; 283 ip->i_d.di_size = pathlen; 284 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); 285 286 cur_chunk = target_path; 287 offset = 0; 288 for (n = 0; n < nmaps; n++) { 289 char *buf; 290 291 d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock); 292 byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount); 293 bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d, 294 BTOBB(byte_cnt), 0); 295 if (!bp) { 296 error = -ENOMEM; 297 goto out_trans_cancel; 298 } 299 bp->b_ops = &xfs_symlink_buf_ops; 300 301 byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt); 302 byte_cnt = min(byte_cnt, pathlen); 303 304 buf = bp->b_addr; 305 buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset, 306 byte_cnt, bp); 307 308 memcpy(buf, cur_chunk, byte_cnt); 309 310 cur_chunk += byte_cnt; 311 pathlen -= byte_cnt; 312 offset += byte_cnt; 313 314 xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF); 315 xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) - 316 (char *)bp->b_addr); 317 } 318 ASSERT(pathlen == 0); 319 } 320 321 /* 322 * Create the directory entry for the symlink. 323 */ 324 error = xfs_dir_createname(tp, dp, link_name, ip->i_ino, resblks); 325 if (error) 326 goto out_trans_cancel; 327 xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG); 328 xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE); 329 330 /* 331 * If this is a synchronous mount, make sure that the 332 * symlink transaction goes to disk before returning to 333 * the user. 334 */ 335 if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) { 336 xfs_trans_set_sync(tp); 337 } 338 339 error = xfs_trans_commit(tp); 340 if (error) 341 goto out_release_inode; 342 343 xfs_qm_dqrele(udqp); 344 xfs_qm_dqrele(gdqp); 345 xfs_qm_dqrele(pdqp); 346 347 *ipp = ip; 348 return 0; 349 350 out_trans_cancel: 351 xfs_trans_cancel(tp); 352 out_release_inode: 353 /* 354 * Wait until after the current transaction is aborted to finish the 355 * setup of the inode and release the inode. This prevents recursive 356 * transactions and deadlocks from xfs_inactive. 357 */ 358 if (ip) { 359 xfs_finish_inode_setup(ip); 360 xfs_irele(ip); 361 } 362 363 xfs_qm_dqrele(udqp); 364 xfs_qm_dqrele(gdqp); 365 xfs_qm_dqrele(pdqp); 366 367 if (unlock_dp_on_error) 368 xfs_iunlock(dp, XFS_ILOCK_EXCL); 369 return error; 370 } 371 372 /* 373 * Free a symlink that has blocks associated with it. 374 * 375 * Note: zero length symlinks are not allowed to exist. When we set the size to 376 * zero, also change it to a regular file so that it does not get written to 377 * disk as a zero length symlink. The inode is on the unlinked list already, so 378 * userspace cannot find this inode anymore, so this change is not user visible 379 * but allows us to catch corrupt zero-length symlinks in the verifiers. 380 */ 381 STATIC int 382 xfs_inactive_symlink_rmt( 383 struct xfs_inode *ip) 384 { 385 xfs_buf_t *bp; 386 int done; 387 int error; 388 int i; 389 xfs_mount_t *mp; 390 xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS]; 391 int nmaps; 392 int size; 393 xfs_trans_t *tp; 394 395 mp = ip->i_mount; 396 ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS); 397 /* 398 * We're freeing a symlink that has some 399 * blocks allocated to it. Free the 400 * blocks here. We know that we've got 401 * either 1 or 2 extents and that we can 402 * free them all in one bunmapi call. 403 */ 404 ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2); 405 406 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp); 407 if (error) 408 return error; 409 410 xfs_ilock(ip, XFS_ILOCK_EXCL); 411 xfs_trans_ijoin(tp, ip, 0); 412 413 /* 414 * Lock the inode, fix the size, turn it into a regular file and join it 415 * to the transaction. Hold it so in the normal path, we still have it 416 * locked for the second transaction. In the error paths we need it 417 * held so the cancel won't rele it, see below. 418 */ 419 size = (int)ip->i_d.di_size; 420 ip->i_d.di_size = 0; 421 VFS_I(ip)->i_mode = (VFS_I(ip)->i_mode & ~S_IFMT) | S_IFREG; 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 pathlen = (int)ip->i_d.di_size; 498 ASSERT(pathlen); 499 500 if (pathlen <= 0 || pathlen > XFS_SYMLINK_MAXLEN) { 501 xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)", 502 __func__, (unsigned long long)ip->i_ino, pathlen); 503 xfs_iunlock(ip, XFS_ILOCK_EXCL); 504 ASSERT(0); 505 return -EFSCORRUPTED; 506 } 507 508 /* 509 * Inline fork state gets removed by xfs_difree() so we have nothing to 510 * do here in that case. 511 */ 512 if (ip->i_df.if_flags & XFS_IFINLINE) { 513 xfs_iunlock(ip, XFS_ILOCK_EXCL); 514 return 0; 515 } 516 517 xfs_iunlock(ip, XFS_ILOCK_EXCL); 518 519 /* remove the remote symlink */ 520 return xfs_inactive_symlink_rmt(ip); 521 } 522