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 | #include "xfs_ialloc.h" |
25 | #include "xfs_error.h" |
26 | |
27 | /* ----- Kernel only functions below ----- */ |
28 | int |
29 | xfs_readlink_bmap_ilocked( |
30 | struct xfs_inode *ip, |
31 | char *link) |
32 | { |
33 | struct xfs_mount *mp = ip->i_mount; |
34 | struct xfs_bmbt_irec mval[XFS_SYMLINK_MAPS]; |
35 | struct xfs_buf *bp; |
36 | xfs_daddr_t d; |
37 | char *cur_chunk; |
38 | int pathlen = ip->i_disk_size; |
39 | int nmaps = XFS_SYMLINK_MAPS; |
40 | int byte_cnt; |
41 | int n; |
42 | int error = 0; |
43 | int fsblocks = 0; |
44 | int offset; |
45 | |
46 | ASSERT(xfs_isilocked(ip, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)); |
47 | |
48 | fsblocks = xfs_symlink_blocks(mp, pathlen); |
49 | error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0); |
50 | if (error) |
51 | goto out; |
52 | |
53 | offset = 0; |
54 | for (n = 0; n < nmaps; n++) { |
55 | d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock); |
56 | byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount); |
57 | |
58 | error = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0, |
59 | &bp, &xfs_symlink_buf_ops); |
60 | if (error) |
61 | return error; |
62 | byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt); |
63 | if (pathlen < byte_cnt) |
64 | byte_cnt = pathlen; |
65 | |
66 | cur_chunk = bp->b_addr; |
67 | if (xfs_has_crc(mp)) { |
68 | if (!xfs_symlink_hdr_ok(ip->i_ino, offset, |
69 | byte_cnt, bp)) { |
70 | error = -EFSCORRUPTED; |
71 | xfs_alert(mp, |
72 | "symlink header does not match required off/len/owner (0x%x/Ox%x,0x%llx)" , |
73 | offset, byte_cnt, ip->i_ino); |
74 | xfs_buf_relse(bp); |
75 | goto out; |
76 | |
77 | } |
78 | |
79 | cur_chunk += sizeof(struct xfs_dsymlink_hdr); |
80 | } |
81 | |
82 | memcpy(link + offset, cur_chunk, byte_cnt); |
83 | |
84 | pathlen -= byte_cnt; |
85 | offset += byte_cnt; |
86 | |
87 | xfs_buf_relse(bp); |
88 | } |
89 | ASSERT(pathlen == 0); |
90 | |
91 | link[ip->i_disk_size] = '\0'; |
92 | error = 0; |
93 | |
94 | out: |
95 | return error; |
96 | } |
97 | |
98 | int |
99 | xfs_readlink( |
100 | struct xfs_inode *ip, |
101 | char *link) |
102 | { |
103 | struct xfs_mount *mp = ip->i_mount; |
104 | xfs_fsize_t pathlen; |
105 | int error = -EFSCORRUPTED; |
106 | |
107 | trace_xfs_readlink(ip); |
108 | |
109 | if (xfs_is_shutdown(mp)) |
110 | return -EIO; |
111 | |
112 | xfs_ilock(ip, XFS_ILOCK_SHARED); |
113 | |
114 | pathlen = ip->i_disk_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 | goto out; |
124 | } |
125 | |
126 | if (ip->i_df.if_format == XFS_DINODE_FMT_LOCAL) { |
127 | /* |
128 | * The VFS crashes on a NULL pointer, so return -EFSCORRUPTED |
129 | * if if_data is junk. |
130 | */ |
131 | if (XFS_IS_CORRUPT(ip->i_mount, !ip->i_df.if_u1.if_data)) |
132 | goto out; |
133 | |
134 | memcpy(link, ip->i_df.if_u1.if_data, pathlen + 1); |
135 | error = 0; |
136 | } else { |
137 | error = xfs_readlink_bmap_ilocked(ip, link); |
138 | } |
139 | |
140 | out: |
141 | xfs_iunlock(ip, XFS_ILOCK_SHARED); |
142 | return error; |
143 | } |
144 | |
145 | int |
146 | xfs_symlink( |
147 | struct mnt_idmap *idmap, |
148 | struct xfs_inode *dp, |
149 | struct xfs_name *link_name, |
150 | const char *target_path, |
151 | umode_t mode, |
152 | struct xfs_inode **ipp) |
153 | { |
154 | struct xfs_mount *mp = dp->i_mount; |
155 | struct xfs_trans *tp = NULL; |
156 | struct xfs_inode *ip = NULL; |
157 | int error = 0; |
158 | int pathlen; |
159 | bool unlock_dp_on_error = false; |
160 | xfs_fileoff_t first_fsb; |
161 | xfs_filblks_t fs_blocks; |
162 | int nmaps; |
163 | struct xfs_bmbt_irec mval[XFS_SYMLINK_MAPS]; |
164 | xfs_daddr_t d; |
165 | const char *cur_chunk; |
166 | int byte_cnt; |
167 | int n; |
168 | struct xfs_buf *bp; |
169 | prid_t prid; |
170 | struct xfs_dquot *udqp = NULL; |
171 | struct xfs_dquot *gdqp = NULL; |
172 | struct xfs_dquot *pdqp = NULL; |
173 | uint resblks; |
174 | xfs_ino_t ino; |
175 | |
176 | *ipp = NULL; |
177 | |
178 | trace_xfs_symlink(dp, xfs_symlink: link_name); |
179 | |
180 | if (xfs_is_shutdown(mp)) |
181 | return -EIO; |
182 | |
183 | /* |
184 | * Check component lengths of the target path name. |
185 | */ |
186 | pathlen = strlen(target_path); |
187 | if (pathlen >= XFS_SYMLINK_MAXLEN) /* total string too long */ |
188 | return -ENAMETOOLONG; |
189 | ASSERT(pathlen > 0); |
190 | |
191 | prid = xfs_get_initial_prid(dp); |
192 | |
193 | /* |
194 | * Make sure that we have allocated dquot(s) on disk. |
195 | */ |
196 | error = xfs_qm_vop_dqalloc(dp, mapped_fsuid(idmap, &init_user_ns), |
197 | mapped_fsgid(idmap, &init_user_ns), 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)) |
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_icreate(mp, resv: &M_RES(mp)->tr_symlink, udqp, gdqp, |
214 | pdqp, dblocks: resblks, tpp: &tp); |
215 | if (error) |
216 | goto out_release_dquots; |
217 | |
218 | xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT); |
219 | unlock_dp_on_error = true; |
220 | |
221 | /* |
222 | * Check whether the directory allows new symlinks or not. |
223 | */ |
224 | if (dp->i_diflags & XFS_DIFLAG_NOSYMLINKS) { |
225 | error = -EPERM; |
226 | goto out_trans_cancel; |
227 | } |
228 | |
229 | /* |
230 | * Allocate an inode for the symlink. |
231 | */ |
232 | error = xfs_dialloc(&tp, dp->i_ino, S_IFLNK, &ino); |
233 | if (!error) |
234 | error = xfs_init_new_inode(idmap, tp, dp, ino, |
235 | S_IFLNK | (mode & ~S_IFMT), 1, 0, prid, |
236 | false, &ip); |
237 | if (error) |
238 | goto out_trans_cancel; |
239 | |
240 | /* |
241 | * Now we join the directory inode to the transaction. We do not do it |
242 | * earlier because xfs_dir_ialloc might commit the previous transaction |
243 | * (and release all the locks). An error from here on will result in |
244 | * the transaction cancel unlocking dp so don't do it explicitly in the |
245 | * error path. |
246 | */ |
247 | xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL); |
248 | unlock_dp_on_error = false; |
249 | |
250 | /* |
251 | * Also attach the dquot(s) to it, if applicable. |
252 | */ |
253 | xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp); |
254 | |
255 | resblks -= XFS_IALLOC_SPACE_RES(mp); |
256 | /* |
257 | * If the symlink will fit into the inode, write it inline. |
258 | */ |
259 | if (pathlen <= xfs_inode_data_fork_size(ip)) { |
260 | xfs_init_local_fork(ip, XFS_DATA_FORK, target_path, pathlen); |
261 | |
262 | ip->i_disk_size = pathlen; |
263 | ip->i_df.if_format = XFS_DINODE_FMT_LOCAL; |
264 | xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE); |
265 | } else { |
266 | int offset; |
267 | |
268 | first_fsb = 0; |
269 | nmaps = XFS_SYMLINK_MAPS; |
270 | |
271 | error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks, |
272 | XFS_BMAPI_METADATA, resblks, mval, &nmaps); |
273 | if (error) |
274 | goto out_trans_cancel; |
275 | |
276 | resblks -= fs_blocks; |
277 | ip->i_disk_size = pathlen; |
278 | xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); |
279 | |
280 | cur_chunk = target_path; |
281 | offset = 0; |
282 | for (n = 0; n < nmaps; n++) { |
283 | char *buf; |
284 | |
285 | d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock); |
286 | byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount); |
287 | error = xfs_trans_get_buf(tp, target: mp->m_ddev_targp, blkno: d, |
288 | numblks: BTOBB(byte_cnt), flags: 0, bpp: &bp); |
289 | if (error) |
290 | goto out_trans_cancel; |
291 | bp->b_ops = &xfs_symlink_buf_ops; |
292 | |
293 | byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt); |
294 | byte_cnt = min(byte_cnt, pathlen); |
295 | |
296 | buf = bp->b_addr; |
297 | buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset, |
298 | byte_cnt, bp); |
299 | |
300 | memcpy(buf, cur_chunk, byte_cnt); |
301 | |
302 | cur_chunk += byte_cnt; |
303 | pathlen -= byte_cnt; |
304 | offset += byte_cnt; |
305 | |
306 | xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF); |
307 | xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) - |
308 | (char *)bp->b_addr); |
309 | } |
310 | ASSERT(pathlen == 0); |
311 | } |
312 | i_size_write(inode: VFS_I(ip), i_size: ip->i_disk_size); |
313 | |
314 | /* |
315 | * Create the directory entry for the symlink. |
316 | */ |
317 | error = xfs_dir_createname(tp, dp, link_name, ip->i_ino, resblks); |
318 | if (error) |
319 | goto out_trans_cancel; |
320 | xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG); |
321 | xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE); |
322 | |
323 | /* |
324 | * If this is a synchronous mount, make sure that the |
325 | * symlink transaction goes to disk before returning to |
326 | * the user. |
327 | */ |
328 | if (xfs_has_wsync(mp) || xfs_has_dirsync(mp)) |
329 | xfs_trans_set_sync(tp); |
330 | |
331 | error = xfs_trans_commit(tp); |
332 | if (error) |
333 | goto out_release_inode; |
334 | |
335 | xfs_qm_dqrele(udqp); |
336 | xfs_qm_dqrele(gdqp); |
337 | xfs_qm_dqrele(pdqp); |
338 | |
339 | *ipp = ip; |
340 | return 0; |
341 | |
342 | out_trans_cancel: |
343 | xfs_trans_cancel(tp); |
344 | out_release_inode: |
345 | /* |
346 | * Wait until after the current transaction is aborted to finish the |
347 | * setup of the inode and release the inode. This prevents recursive |
348 | * transactions and deadlocks from xfs_inactive. |
349 | */ |
350 | if (ip) { |
351 | xfs_finish_inode_setup(ip); |
352 | xfs_irele(ip); |
353 | } |
354 | out_release_dquots: |
355 | xfs_qm_dqrele(udqp); |
356 | xfs_qm_dqrele(gdqp); |
357 | xfs_qm_dqrele(pdqp); |
358 | |
359 | if (unlock_dp_on_error) |
360 | xfs_iunlock(dp, XFS_ILOCK_EXCL); |
361 | return error; |
362 | } |
363 | |
364 | /* |
365 | * Free a symlink that has blocks associated with it. |
366 | * |
367 | * Note: zero length symlinks are not allowed to exist. When we set the size to |
368 | * zero, also change it to a regular file so that it does not get written to |
369 | * disk as a zero length symlink. The inode is on the unlinked list already, so |
370 | * userspace cannot find this inode anymore, so this change is not user visible |
371 | * but allows us to catch corrupt zero-length symlinks in the verifiers. |
372 | */ |
373 | STATIC int |
374 | xfs_inactive_symlink_rmt( |
375 | struct xfs_inode *ip) |
376 | { |
377 | struct xfs_buf *bp; |
378 | int done; |
379 | int error; |
380 | int i; |
381 | xfs_mount_t *mp; |
382 | xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS]; |
383 | int nmaps; |
384 | int size; |
385 | xfs_trans_t *tp; |
386 | |
387 | mp = ip->i_mount; |
388 | ASSERT(!xfs_need_iread_extents(&ip->i_df)); |
389 | /* |
390 | * We're freeing a symlink that has some |
391 | * blocks allocated to it. Free the |
392 | * blocks here. We know that we've got |
393 | * either 1 or 2 extents and that we can |
394 | * free them all in one bunmapi call. |
395 | */ |
396 | ASSERT(ip->i_df.if_nextents > 0 && ip->i_df.if_nextents <= 2); |
397 | |
398 | error = xfs_trans_alloc(mp, resp: &M_RES(mp)->tr_itruncate, blocks: 0, rtextents: 0, flags: 0, tpp: &tp); |
399 | if (error) |
400 | return error; |
401 | |
402 | xfs_ilock(ip, XFS_ILOCK_EXCL); |
403 | xfs_trans_ijoin(tp, ip, 0); |
404 | |
405 | /* |
406 | * Lock the inode, fix the size, turn it into a regular file and join it |
407 | * to the transaction. Hold it so in the normal path, we still have it |
408 | * locked for the second transaction. In the error paths we need it |
409 | * held so the cancel won't rele it, see below. |
410 | */ |
411 | size = (int)ip->i_disk_size; |
412 | ip->i_disk_size = 0; |
413 | VFS_I(ip)->i_mode = (VFS_I(ip)->i_mode & ~S_IFMT) | S_IFREG; |
414 | xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); |
415 | /* |
416 | * Find the block(s) so we can inval and unmap them. |
417 | */ |
418 | done = 0; |
419 | nmaps = ARRAY_SIZE(mval); |
420 | error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size), |
421 | mval, &nmaps, 0); |
422 | if (error) |
423 | goto error_trans_cancel; |
424 | /* |
425 | * Invalidate the block(s). No validation is done. |
426 | */ |
427 | for (i = 0; i < nmaps; i++) { |
428 | error = xfs_trans_get_buf(tp, mp->m_ddev_targp, |
429 | XFS_FSB_TO_DADDR(mp, mval[i].br_startblock), |
430 | XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0, |
431 | &bp); |
432 | if (error) |
433 | goto error_trans_cancel; |
434 | xfs_trans_binval(tp, bp); |
435 | } |
436 | /* |
437 | * Unmap the dead block(s) to the dfops. |
438 | */ |
439 | error = xfs_bunmapi(tp, ip, 0, size, 0, nmaps, &done); |
440 | if (error) |
441 | goto error_trans_cancel; |
442 | ASSERT(done); |
443 | |
444 | /* |
445 | * Commit the transaction. This first logs the EFI and the inode, then |
446 | * rolls and commits the transaction that frees the extents. |
447 | */ |
448 | xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); |
449 | error = xfs_trans_commit(tp); |
450 | if (error) { |
451 | ASSERT(xfs_is_shutdown(mp)); |
452 | goto error_unlock; |
453 | } |
454 | |
455 | /* |
456 | * Remove the memory for extent descriptions (just bookkeeping). |
457 | */ |
458 | if (ip->i_df.if_bytes) |
459 | xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK); |
460 | ASSERT(ip->i_df.if_bytes == 0); |
461 | |
462 | xfs_iunlock(ip, XFS_ILOCK_EXCL); |
463 | return 0; |
464 | |
465 | error_trans_cancel: |
466 | xfs_trans_cancel(tp); |
467 | error_unlock: |
468 | xfs_iunlock(ip, XFS_ILOCK_EXCL); |
469 | return error; |
470 | } |
471 | |
472 | /* |
473 | * xfs_inactive_symlink - free a symlink |
474 | */ |
475 | int |
476 | xfs_inactive_symlink( |
477 | struct xfs_inode *ip) |
478 | { |
479 | struct xfs_mount *mp = ip->i_mount; |
480 | int pathlen; |
481 | |
482 | trace_xfs_inactive_symlink(ip); |
483 | |
484 | if (xfs_is_shutdown(mp)) |
485 | return -EIO; |
486 | |
487 | xfs_ilock(ip, XFS_ILOCK_EXCL); |
488 | pathlen = (int)ip->i_disk_size; |
489 | ASSERT(pathlen); |
490 | |
491 | if (pathlen <= 0 || pathlen > XFS_SYMLINK_MAXLEN) { |
492 | xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)" , |
493 | __func__, (unsigned long long)ip->i_ino, pathlen); |
494 | xfs_iunlock(ip, XFS_ILOCK_EXCL); |
495 | ASSERT(0); |
496 | return -EFSCORRUPTED; |
497 | } |
498 | |
499 | /* |
500 | * Inline fork state gets removed by xfs_difree() so we have nothing to |
501 | * do here in that case. |
502 | */ |
503 | if (ip->i_df.if_format == XFS_DINODE_FMT_LOCAL) { |
504 | xfs_iunlock(ip, XFS_ILOCK_EXCL); |
505 | return 0; |
506 | } |
507 | |
508 | xfs_iunlock(ip, XFS_ILOCK_EXCL); |
509 | |
510 | /* remove the remote symlink */ |
511 | return xfs_inactive_symlink_rmt(ip); |
512 | } |
513 | |