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,
195 xfs_kuid_to_uid(current_fsuid()),
196 xfs_kgid_to_gid(current_fsgid()), prid,
197 XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
198 &udqp, &gdqp, &pdqp);
199 if (error)
200 return error;
201
202 /*
203 * The symlink will fit into the inode data fork?
204 * There can't be any attributes so we get the whole variable part.
205 */
206 if (pathlen <= XFS_LITINO(mp, dp->i_d.di_version))
207 fs_blocks = 0;
208 else
209 fs_blocks = xfs_symlink_blocks(mp, pathlen);
210 resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
211
212 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_symlink, resblks, 0, 0, &tp);
213 if (error)
214 goto out_release_inode;
215
216 xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
217 unlock_dp_on_error = true;
218
219 /*
220 * Check whether the directory allows new symlinks or not.
221 */
222 if (dp->i_d.di_flags & XFS_DIFLAG_NOSYMLINKS) {
223 error = -EPERM;
224 goto out_trans_cancel;
225 }
226
227 /*
228 * Reserve disk quota : blocks and inode.
229 */
230 error = xfs_trans_reserve_quota(tp, mp, udqp, gdqp,
231 pdqp, resblks, 1, 0);
232 if (error)
233 goto out_trans_cancel;
234
235 /*
236 * Allocate an inode for the symlink.
237 */
238 error = xfs_dir_ialloc(&tp, dp, S_IFLNK | (mode & ~S_IFMT), 1, 0,
239 prid, &ip);
240 if (error)
241 goto out_trans_cancel;
242
243 /*
244 * Now we join the directory inode to the transaction. We do not do it
245 * earlier because xfs_dir_ialloc might commit the previous transaction
246 * (and release all the locks). An error from here on will result in
247 * the transaction cancel unlocking dp so don't do it explicitly in the
248 * error path.
249 */
250 xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
251 unlock_dp_on_error = false;
252
253 /*
254 * Also attach the dquot(s) to it, if applicable.
255 */
256 xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
257
258 if (resblks)
259 resblks -= XFS_IALLOC_SPACE_RES(mp);
260 /*
261 * If the symlink will fit into the inode, write it inline.
262 */
263 if (pathlen <= XFS_IFORK_DSIZE(ip)) {
264 xfs_init_local_fork(ip, XFS_DATA_FORK, target_path, pathlen);
265
266 ip->i_d.di_size = pathlen;
267 ip->i_d.di_format = XFS_DINODE_FMT_LOCAL;
268 xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);
269 } else {
270 int offset;
271
272 first_fsb = 0;
273 nmaps = XFS_SYMLINK_MAPS;
274
275 error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks,
276 XFS_BMAPI_METADATA, resblks, mval, &nmaps);
277 if (error)
278 goto out_trans_cancel;
279
280 if (resblks)
281 resblks -= fs_blocks;
282 ip->i_d.di_size = pathlen;
283 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
284
285 cur_chunk = target_path;
286 offset = 0;
287 for (n = 0; n < nmaps; n++) {
288 char *buf;
289
290 d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
291 byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
292 bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
293 BTOBB(byte_cnt), 0);
294 if (!bp) {
295 error = -ENOMEM;
296 goto out_trans_cancel;
297 }
298 bp->b_ops = &xfs_symlink_buf_ops;
299
300 byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
301 byte_cnt = min(byte_cnt, pathlen);
302
303 buf = bp->b_addr;
304 buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset,
305 byte_cnt, bp);
306
307 memcpy(buf, cur_chunk, byte_cnt);
308
309 cur_chunk += byte_cnt;
310 pathlen -= byte_cnt;
311 offset += byte_cnt;
312
313 xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
314 xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
315 (char *)bp->b_addr);
316 }
317 ASSERT(pathlen == 0);
318 }
319
320 /*
321 * Create the directory entry for the symlink.
322 */
323 error = xfs_dir_createname(tp, dp, link_name, ip->i_ino, resblks);
324 if (error)
325 goto out_trans_cancel;
326 xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
327 xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
328
329 /*
330 * If this is a synchronous mount, make sure that the
331 * symlink transaction goes to disk before returning to
332 * the user.
333 */
334 if (mp->m_flags & (XFS_MOUNT_WSYNC|XFS_MOUNT_DIRSYNC)) {
335 xfs_trans_set_sync(tp);
336 }
337
338 error = xfs_trans_commit(tp);
339 if (error)
340 goto out_release_inode;
341
342 xfs_qm_dqrele(udqp);
343 xfs_qm_dqrele(gdqp);
344 xfs_qm_dqrele(pdqp);
345
346 *ipp = ip;
347 return 0;
348
349 out_trans_cancel:
350 xfs_trans_cancel(tp);
351 out_release_inode:
352 /*
353 * Wait until after the current transaction is aborted to finish the
354 * setup of the inode and release the inode. This prevents recursive
355 * transactions and deadlocks from xfs_inactive.
356 */
357 if (ip) {
358 xfs_finish_inode_setup(ip);
359 xfs_irele(ip);
360 }
361
362 xfs_qm_dqrele(udqp);
363 xfs_qm_dqrele(gdqp);
364 xfs_qm_dqrele(pdqp);
365
366 if (unlock_dp_on_error)
367 xfs_iunlock(dp, XFS_ILOCK_EXCL);
368 return error;
369 }
370
371 /*
372 * Free a symlink that has blocks associated with it.
373 *
374 * Note: zero length symlinks are not allowed to exist. When we set the size to
375 * zero, also change it to a regular file so that it does not get written to
376 * disk as a zero length symlink. The inode is on the unlinked list already, so
377 * userspace cannot find this inode anymore, so this change is not user visible
378 * but allows us to catch corrupt zero-length symlinks in the verifiers.
379 */
380 STATIC int
xfs_inactive_symlink_rmt(struct xfs_inode * ip)381 xfs_inactive_symlink_rmt(
382 struct xfs_inode *ip)
383 {
384 xfs_buf_t *bp;
385 int done;
386 int error;
387 int i;
388 xfs_mount_t *mp;
389 xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS];
390 int nmaps;
391 int size;
392 xfs_trans_t *tp;
393
394 mp = ip->i_mount;
395 ASSERT(ip->i_df.if_flags & XFS_IFEXTENTS);
396 /*
397 * We're freeing a symlink that has some
398 * blocks allocated to it. Free the
399 * blocks here. We know that we've got
400 * either 1 or 2 extents and that we can
401 * free them all in one bunmapi call.
402 */
403 ASSERT(ip->i_d.di_nextents > 0 && ip->i_d.di_nextents <= 2);
404
405 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
406 if (error)
407 return error;
408
409 xfs_ilock(ip, XFS_ILOCK_EXCL);
410 xfs_trans_ijoin(tp, ip, 0);
411
412 /*
413 * Lock the inode, fix the size, turn it into a regular file and join it
414 * to the transaction. Hold it so in the normal path, we still have it
415 * locked for the second transaction. In the error paths we need it
416 * held so the cancel won't rele it, see below.
417 */
418 size = (int)ip->i_d.di_size;
419 ip->i_d.di_size = 0;
420 VFS_I(ip)->i_mode = (VFS_I(ip)->i_mode & ~S_IFMT) | S_IFREG;
421 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
422 /*
423 * Find the block(s) so we can inval and unmap them.
424 */
425 done = 0;
426 nmaps = ARRAY_SIZE(mval);
427 error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
428 mval, &nmaps, 0);
429 if (error)
430 goto error_trans_cancel;
431 /*
432 * Invalidate the block(s). No validation is done.
433 */
434 for (i = 0; i < nmaps; i++) {
435 bp = xfs_trans_get_buf(tp, mp->m_ddev_targp,
436 XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
437 XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0);
438 if (!bp) {
439 error = -ENOMEM;
440 goto error_trans_cancel;
441 }
442 xfs_trans_binval(tp, bp);
443 }
444 /*
445 * Unmap the dead block(s) to the dfops.
446 */
447 error = xfs_bunmapi(tp, ip, 0, size, 0, nmaps, &done);
448 if (error)
449 goto error_trans_cancel;
450 ASSERT(done);
451
452 /*
453 * Commit the transaction. This first logs the EFI and the inode, then
454 * rolls and commits the transaction that frees the extents.
455 */
456 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
457 error = xfs_trans_commit(tp);
458 if (error) {
459 ASSERT(XFS_FORCED_SHUTDOWN(mp));
460 goto error_unlock;
461 }
462
463 /*
464 * Remove the memory for extent descriptions (just bookkeeping).
465 */
466 if (ip->i_df.if_bytes)
467 xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
468 ASSERT(ip->i_df.if_bytes == 0);
469
470 xfs_iunlock(ip, XFS_ILOCK_EXCL);
471 return 0;
472
473 error_trans_cancel:
474 xfs_trans_cancel(tp);
475 error_unlock:
476 xfs_iunlock(ip, XFS_ILOCK_EXCL);
477 return error;
478 }
479
480 /*
481 * xfs_inactive_symlink - free a symlink
482 */
483 int
xfs_inactive_symlink(struct xfs_inode * ip)484 xfs_inactive_symlink(
485 struct xfs_inode *ip)
486 {
487 struct xfs_mount *mp = ip->i_mount;
488 int pathlen;
489
490 trace_xfs_inactive_symlink(ip);
491
492 if (XFS_FORCED_SHUTDOWN(mp))
493 return -EIO;
494
495 xfs_ilock(ip, XFS_ILOCK_EXCL);
496 pathlen = (int)ip->i_d.di_size;
497 ASSERT(pathlen);
498
499 if (pathlen <= 0 || pathlen > XFS_SYMLINK_MAXLEN) {
500 xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
501 __func__, (unsigned long long)ip->i_ino, pathlen);
502 xfs_iunlock(ip, XFS_ILOCK_EXCL);
503 ASSERT(0);
504 return -EFSCORRUPTED;
505 }
506
507 /*
508 * Inline fork state gets removed by xfs_difree() so we have nothing to
509 * do here in that case.
510 */
511 if (ip->i_df.if_flags & XFS_IFINLINE) {
512 xfs_iunlock(ip, XFS_ILOCK_EXCL);
513 return 0;
514 }
515
516 xfs_iunlock(ip, XFS_ILOCK_EXCL);
517
518 /* remove the remote symlink */
519 return xfs_inactive_symlink_rmt(ip);
520 }
521