xfs_symlink.c revision 75c8c50f
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 ----- */
27int
28xfs_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
97int
98xfs_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
136int
137xfs_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
338out_trans_cancel:
339	xfs_trans_cancel(tp);
340out_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	}
350out_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 */
369STATIC int
370xfs_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
461error_trans_cancel:
462	xfs_trans_cancel(tp);
463error_unlock:
464	xfs_iunlock(ip, XFS_ILOCK_EXCL);
465	return error;
466}
467
468/*
469 * xfs_inactive_symlink - free a symlink
470 */
471int
472xfs_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