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
xfs_readlink_bmap_ilocked(struct xfs_inode * ip,char * link)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
xfs_readlink(struct xfs_inode * ip,char * link)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
xfs_symlink(struct user_namespace * mnt_userns,struct xfs_inode * dp,struct xfs_name * link_name,const char * target_path,umode_t mode,struct xfs_inode ** ipp)146 xfs_symlink(
147 struct user_namespace *mnt_userns,
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, 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(mnt_userns, &init_user_ns),
197 mapped_fsgid(mnt_userns, &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, &M_RES(mp)->tr_symlink, udqp, gdqp,
214 pdqp, resblks, &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(mnt_userns, 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, mp->m_ddev_targp, d,
288 BTOBB(byte_cnt), 0, &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(VFS_I(ip), 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
xfs_inactive_symlink_rmt(struct xfs_inode * ip)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, &M_RES(mp)->tr_itruncate, 0, 0, 0, &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
xfs_inactive_symlink(struct xfs_inode * ip)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