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