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