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
26 /* ----- Kernel only functions below ----- */
27 int
xfs_readlink_bmap_ilocked(struct xfs_inode * ip,char * link)28 xfs_readlink_bmap_ilocked(
29 struct xfs_inode *ip,
30 char *link)
31 {
32 struct xfs_mount *mp = ip->i_mount;
33 struct xfs_bmbt_irec mval[XFS_SYMLINK_MAPS];
34 struct xfs_buf *bp;
35 xfs_daddr_t d;
36 char *cur_chunk;
37 int pathlen = ip->i_disk_size;
38 int nmaps = XFS_SYMLINK_MAPS;
39 int byte_cnt;
40 int n;
41 int error = 0;
42 int fsblocks = 0;
43 int offset;
44
45 ASSERT(xfs_isilocked(ip, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
46
47 fsblocks = xfs_symlink_blocks(mp, pathlen);
48 error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0);
49 if (error)
50 goto out;
51
52 offset = 0;
53 for (n = 0; n < nmaps; n++) {
54 d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
55 byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
56
57 error = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
58 &bp, &xfs_symlink_buf_ops);
59 if (error)
60 return error;
61 byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
62 if (pathlen < byte_cnt)
63 byte_cnt = pathlen;
64
65 cur_chunk = bp->b_addr;
66 if (xfs_has_crc(mp)) {
67 if (!xfs_symlink_hdr_ok(ip->i_ino, offset,
68 byte_cnt, bp)) {
69 error = -EFSCORRUPTED;
70 xfs_alert(mp,
71 "symlink header does not match required off/len/owner (0x%x/Ox%x,0x%llx)",
72 offset, byte_cnt, ip->i_ino);
73 xfs_buf_relse(bp);
74 goto out;
75
76 }
77
78 cur_chunk += sizeof(struct xfs_dsymlink_hdr);
79 }
80
81 memcpy(link + offset, cur_chunk, byte_cnt);
82
83 pathlen -= byte_cnt;
84 offset += byte_cnt;
85
86 xfs_buf_relse(bp);
87 }
88 ASSERT(pathlen == 0);
89
90 link[ip->i_disk_size] = '\0';
91 error = 0;
92
93 out:
94 return error;
95 }
96
97 int
xfs_readlink(struct xfs_inode * ip,char * link)98 xfs_readlink(
99 struct xfs_inode *ip,
100 char *link)
101 {
102 struct xfs_mount *mp = ip->i_mount;
103 xfs_fsize_t pathlen;
104 int error = 0;
105
106 trace_xfs_readlink(ip);
107
108 ASSERT(ip->i_df.if_format != XFS_DINODE_FMT_LOCAL);
109
110 if (xfs_is_shutdown(mp))
111 return -EIO;
112
113 xfs_ilock(ip, XFS_ILOCK_SHARED);
114
115 pathlen = ip->i_disk_size;
116 if (!pathlen)
117 goto out;
118
119 if (pathlen < 0 || pathlen > XFS_SYMLINK_MAXLEN) {
120 xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)",
121 __func__, (unsigned long long) ip->i_ino,
122 (long long) pathlen);
123 ASSERT(0);
124 error = -EFSCORRUPTED;
125 goto out;
126 }
127
128
129 error = xfs_readlink_bmap_ilocked(ip, link);
130
131 out:
132 xfs_iunlock(ip, XFS_ILOCK_SHARED);
133 return error;
134 }
135
136 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)137 xfs_symlink(
138 struct user_namespace *mnt_userns,
139 struct xfs_inode *dp,
140 struct xfs_name *link_name,
141 const char *target_path,
142 umode_t mode,
143 struct xfs_inode **ipp)
144 {
145 struct xfs_mount *mp = dp->i_mount;
146 struct xfs_trans *tp = NULL;
147 struct xfs_inode *ip = NULL;
148 int error = 0;
149 int pathlen;
150 bool unlock_dp_on_error = false;
151 xfs_fileoff_t first_fsb;
152 xfs_filblks_t fs_blocks;
153 int nmaps;
154 struct xfs_bmbt_irec mval[XFS_SYMLINK_MAPS];
155 xfs_daddr_t d;
156 const char *cur_chunk;
157 int byte_cnt;
158 int n;
159 struct xfs_buf *bp;
160 prid_t prid;
161 struct xfs_dquot *udqp = NULL;
162 struct xfs_dquot *gdqp = NULL;
163 struct xfs_dquot *pdqp = NULL;
164 uint resblks;
165 xfs_ino_t ino;
166
167 *ipp = NULL;
168
169 trace_xfs_symlink(dp, link_name);
170
171 if (xfs_is_shutdown(mp))
172 return -EIO;
173
174 /*
175 * Check component lengths of the target path name.
176 */
177 pathlen = strlen(target_path);
178 if (pathlen >= XFS_SYMLINK_MAXLEN) /* total string too long */
179 return -ENAMETOOLONG;
180 ASSERT(pathlen > 0);
181
182 prid = xfs_get_initial_prid(dp);
183
184 /*
185 * Make sure that we have allocated dquot(s) on disk.
186 */
187 error = xfs_qm_vop_dqalloc(dp, mapped_fsuid(mnt_userns),
188 mapped_fsgid(mnt_userns), prid,
189 XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
190 &udqp, &gdqp, &pdqp);
191 if (error)
192 return error;
193
194 /*
195 * The symlink will fit into the inode data fork?
196 * There can't be any attributes so we get the whole variable part.
197 */
198 if (pathlen <= XFS_LITINO(mp))
199 fs_blocks = 0;
200 else
201 fs_blocks = xfs_symlink_blocks(mp, pathlen);
202 resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
203
204 error = xfs_trans_alloc_icreate(mp, &M_RES(mp)->tr_symlink, udqp, gdqp,
205 pdqp, resblks, &tp);
206 if (error)
207 goto out_release_dquots;
208
209 xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
210 unlock_dp_on_error = true;
211
212 /*
213 * Check whether the directory allows new symlinks or not.
214 */
215 if (dp->i_diflags & XFS_DIFLAG_NOSYMLINKS) {
216 error = -EPERM;
217 goto out_trans_cancel;
218 }
219
220 error = xfs_iext_count_may_overflow(dp, XFS_DATA_FORK,
221 XFS_IEXT_DIR_MANIP_CNT(mp));
222 if (error)
223 goto out_trans_cancel;
224
225 /*
226 * Allocate an inode for the symlink.
227 */
228 error = xfs_dialloc(&tp, dp->i_ino, S_IFLNK, &ino);
229 if (!error)
230 error = xfs_init_new_inode(mnt_userns, tp, dp, ino,
231 S_IFLNK | (mode & ~S_IFMT), 1, 0, prid,
232 false, &ip);
233 if (error)
234 goto out_trans_cancel;
235
236 /*
237 * Now we join the directory inode to the transaction. We do not do it
238 * earlier because xfs_dir_ialloc might commit the previous transaction
239 * (and release all the locks). An error from here on will result in
240 * the transaction cancel unlocking dp so don't do it explicitly in the
241 * error path.
242 */
243 xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
244 unlock_dp_on_error = false;
245
246 /*
247 * Also attach the dquot(s) to it, if applicable.
248 */
249 xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
250
251 resblks -= XFS_IALLOC_SPACE_RES(mp);
252 /*
253 * If the symlink will fit into the inode, write it inline.
254 */
255 if (pathlen <= XFS_IFORK_DSIZE(ip)) {
256 xfs_init_local_fork(ip, XFS_DATA_FORK, target_path, pathlen);
257
258 ip->i_disk_size = pathlen;
259 ip->i_df.if_format = XFS_DINODE_FMT_LOCAL;
260 xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);
261 } else {
262 int offset;
263
264 first_fsb = 0;
265 nmaps = XFS_SYMLINK_MAPS;
266
267 error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks,
268 XFS_BMAPI_METADATA, resblks, mval, &nmaps);
269 if (error)
270 goto out_trans_cancel;
271
272 resblks -= fs_blocks;
273 ip->i_disk_size = pathlen;
274 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
275
276 cur_chunk = target_path;
277 offset = 0;
278 for (n = 0; n < nmaps; n++) {
279 char *buf;
280
281 d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
282 byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
283 error = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
284 BTOBB(byte_cnt), 0, &bp);
285 if (error)
286 goto out_trans_cancel;
287 bp->b_ops = &xfs_symlink_buf_ops;
288
289 byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
290 byte_cnt = min(byte_cnt, pathlen);
291
292 buf = bp->b_addr;
293 buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset,
294 byte_cnt, bp);
295
296 memcpy(buf, cur_chunk, byte_cnt);
297
298 cur_chunk += byte_cnt;
299 pathlen -= byte_cnt;
300 offset += byte_cnt;
301
302 xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
303 xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
304 (char *)bp->b_addr);
305 }
306 ASSERT(pathlen == 0);
307 }
308 i_size_write(VFS_I(ip), ip->i_disk_size);
309
310 /*
311 * Create the directory entry for the symlink.
312 */
313 error = xfs_dir_createname(tp, dp, link_name, ip->i_ino, resblks);
314 if (error)
315 goto out_trans_cancel;
316 xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
317 xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
318
319 /*
320 * If this is a synchronous mount, make sure that the
321 * symlink transaction goes to disk before returning to
322 * the user.
323 */
324 if (xfs_has_wsync(mp) || xfs_has_dirsync(mp))
325 xfs_trans_set_sync(tp);
326
327 error = xfs_trans_commit(tp);
328 if (error)
329 goto out_release_inode;
330
331 xfs_qm_dqrele(udqp);
332 xfs_qm_dqrele(gdqp);
333 xfs_qm_dqrele(pdqp);
334
335 *ipp = ip;
336 return 0;
337
338 out_trans_cancel:
339 xfs_trans_cancel(tp);
340 out_release_inode:
341 /*
342 * Wait until after the current transaction is aborted to finish the
343 * setup of the inode and release the inode. This prevents recursive
344 * transactions and deadlocks from xfs_inactive.
345 */
346 if (ip) {
347 xfs_finish_inode_setup(ip);
348 xfs_irele(ip);
349 }
350 out_release_dquots:
351 xfs_qm_dqrele(udqp);
352 xfs_qm_dqrele(gdqp);
353 xfs_qm_dqrele(pdqp);
354
355 if (unlock_dp_on_error)
356 xfs_iunlock(dp, XFS_ILOCK_EXCL);
357 return error;
358 }
359
360 /*
361 * Free a symlink that has blocks associated with it.
362 *
363 * Note: zero length symlinks are not allowed to exist. When we set the size to
364 * zero, also change it to a regular file so that it does not get written to
365 * disk as a zero length symlink. The inode is on the unlinked list already, so
366 * userspace cannot find this inode anymore, so this change is not user visible
367 * but allows us to catch corrupt zero-length symlinks in the verifiers.
368 */
369 STATIC int
xfs_inactive_symlink_rmt(struct xfs_inode * ip)370 xfs_inactive_symlink_rmt(
371 struct xfs_inode *ip)
372 {
373 struct xfs_buf *bp;
374 int done;
375 int error;
376 int i;
377 xfs_mount_t *mp;
378 xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS];
379 int nmaps;
380 int size;
381 xfs_trans_t *tp;
382
383 mp = ip->i_mount;
384 ASSERT(!xfs_need_iread_extents(&ip->i_df));
385 /*
386 * We're freeing a symlink that has some
387 * blocks allocated to it. Free the
388 * blocks here. We know that we've got
389 * either 1 or 2 extents and that we can
390 * free them all in one bunmapi call.
391 */
392 ASSERT(ip->i_df.if_nextents > 0 && ip->i_df.if_nextents <= 2);
393
394 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
395 if (error)
396 return error;
397
398 xfs_ilock(ip, XFS_ILOCK_EXCL);
399 xfs_trans_ijoin(tp, ip, 0);
400
401 /*
402 * Lock the inode, fix the size, turn it into a regular file and join it
403 * to the transaction. Hold it so in the normal path, we still have it
404 * locked for the second transaction. In the error paths we need it
405 * held so the cancel won't rele it, see below.
406 */
407 size = (int)ip->i_disk_size;
408 ip->i_disk_size = 0;
409 VFS_I(ip)->i_mode = (VFS_I(ip)->i_mode & ~S_IFMT) | S_IFREG;
410 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
411 /*
412 * Find the block(s) so we can inval and unmap them.
413 */
414 done = 0;
415 nmaps = ARRAY_SIZE(mval);
416 error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
417 mval, &nmaps, 0);
418 if (error)
419 goto error_trans_cancel;
420 /*
421 * Invalidate the block(s). No validation is done.
422 */
423 for (i = 0; i < nmaps; i++) {
424 error = xfs_trans_get_buf(tp, mp->m_ddev_targp,
425 XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
426 XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0,
427 &bp);
428 if (error)
429 goto error_trans_cancel;
430 xfs_trans_binval(tp, bp);
431 }
432 /*
433 * Unmap the dead block(s) to the dfops.
434 */
435 error = xfs_bunmapi(tp, ip, 0, size, 0, nmaps, &done);
436 if (error)
437 goto error_trans_cancel;
438 ASSERT(done);
439
440 /*
441 * Commit the transaction. This first logs the EFI and the inode, then
442 * rolls and commits the transaction that frees the extents.
443 */
444 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
445 error = xfs_trans_commit(tp);
446 if (error) {
447 ASSERT(xfs_is_shutdown(mp));
448 goto error_unlock;
449 }
450
451 /*
452 * Remove the memory for extent descriptions (just bookkeeping).
453 */
454 if (ip->i_df.if_bytes)
455 xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
456 ASSERT(ip->i_df.if_bytes == 0);
457
458 xfs_iunlock(ip, XFS_ILOCK_EXCL);
459 return 0;
460
461 error_trans_cancel:
462 xfs_trans_cancel(tp);
463 error_unlock:
464 xfs_iunlock(ip, XFS_ILOCK_EXCL);
465 return error;
466 }
467
468 /*
469 * xfs_inactive_symlink - free a symlink
470 */
471 int
xfs_inactive_symlink(struct xfs_inode * ip)472 xfs_inactive_symlink(
473 struct xfs_inode *ip)
474 {
475 struct xfs_mount *mp = ip->i_mount;
476 int pathlen;
477
478 trace_xfs_inactive_symlink(ip);
479
480 if (xfs_is_shutdown(mp))
481 return -EIO;
482
483 xfs_ilock(ip, XFS_ILOCK_EXCL);
484 pathlen = (int)ip->i_disk_size;
485 ASSERT(pathlen);
486
487 if (pathlen <= 0 || pathlen > XFS_SYMLINK_MAXLEN) {
488 xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
489 __func__, (unsigned long long)ip->i_ino, pathlen);
490 xfs_iunlock(ip, XFS_ILOCK_EXCL);
491 ASSERT(0);
492 return -EFSCORRUPTED;
493 }
494
495 /*
496 * Inline fork state gets removed by xfs_difree() so we have nothing to
497 * do here in that case.
498 */
499 if (ip->i_df.if_format == XFS_DINODE_FMT_LOCAL) {
500 xfs_iunlock(ip, XFS_ILOCK_EXCL);
501 return 0;
502 }
503
504 xfs_iunlock(ip, XFS_ILOCK_EXCL);
505
506 /* remove the remote symlink */
507 return xfs_inactive_symlink_rmt(ip);
508 }
509