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
xfs_readlink_bmap_ilocked(struct xfs_inode * ip,char * link)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
xfs_readlink(struct xfs_inode * ip,char * link)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
xfs_symlink(struct xfs_inode * dp,struct xfs_name * link_name,const char * target_path,umode_t mode,struct xfs_inode ** ipp)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
xfs_inactive_symlink_rmt(struct xfs_inode * ip)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
xfs_inactive_symlink(struct xfs_inode * ip)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