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