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