xfs_symlink_remote.c

  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_fs.h"
  9#include "xfs_format.h"
 10#include "xfs_log_format.h"
 11#include "xfs_shared.h"
 12#include "xfs_trans_resv.h"
 13#include "xfs_mount.h"
 14#include "xfs_inode.h"
 15#include "xfs_error.h"
 16#include "xfs_trans.h"
 17#include "xfs_buf_item.h"
 18#include "xfs_log.h"
 19#include "xfs_symlink_remote.h"
 20#include "xfs_bit.h"
 21#include "xfs_bmap.h"
 22#include "xfs_health.h"
 23
 24/*
 25 * Each contiguous block has a header, so it is not just a simple pathlen
 26 * to FSB conversion.
 27 */
 28int
 29xfs_symlink_blocks(
 30	struct xfs_mount *mp,
 31	int		pathlen)
 32{
 33	int buflen = XFS_SYMLINK_BUF_SPACE(mp, mp->m_sb.sb_blocksize);
 34
 35	return (pathlen + buflen - 1) / buflen;
 36}
 37
 38int
 39xfs_symlink_hdr_set(
 40	struct xfs_mount	*mp,
 41	xfs_ino_t		ino,
 42	uint32_t		offset,
 43	uint32_t		size,
 44	struct xfs_buf		*bp)
 45{
 46	struct xfs_dsymlink_hdr	*dsl = bp->b_addr;
 47
 48	if (!xfs_has_crc(mp))
 49		return 0;
 50
 51	memset(dsl, 0, sizeof(struct xfs_dsymlink_hdr));
 52	dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
 53	dsl->sl_offset = cpu_to_be32(offset);
 54	dsl->sl_bytes = cpu_to_be32(size);
 55	uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid);
 56	dsl->sl_owner = cpu_to_be64(ino);
 57	dsl->sl_blkno = cpu_to_be64(xfs_buf_daddr(bp));
 58	bp->b_ops = &xfs_symlink_buf_ops;
 59
 60	return sizeof(struct xfs_dsymlink_hdr);
 61}
 62
 63/*
 64 * Checking of the symlink header is split into two parts. the verifier does
 65 * CRC, location and bounds checking, the unpacking function checks the path
 66 * parameters and owner.
 67 */
 68bool
 69xfs_symlink_hdr_ok(
 70	xfs_ino_t		ino,
 71	uint32_t		offset,
 72	uint32_t		size,
 73	struct xfs_buf		*bp)
 74{
 75	struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 76
 77	if (offset != be32_to_cpu(dsl->sl_offset))
 78		return false;
 79	if (size != be32_to_cpu(dsl->sl_bytes))
 80		return false;
 81	if (ino != be64_to_cpu(dsl->sl_owner))
 82		return false;
 83
 84	/* ok */
 85	return true;
 86}
 87
 88static xfs_failaddr_t
 89xfs_symlink_verify(
 90	struct xfs_buf		*bp)
 91{
 92	struct xfs_mount	*mp = bp->b_mount;
 93	struct xfs_dsymlink_hdr	*dsl = bp->b_addr;
 94
 95	/* no verification of non-crc buffers */
 96	if (!xfs_has_crc(mp))
 97		return NULL;
 98
 99	if (!xfs_verify_magic(bp, dsl->sl_magic))
100		return __this_address;
101	if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid))
102		return __this_address;
103	if (xfs_buf_daddr(bp) != be64_to_cpu(dsl->sl_blkno))
104		return __this_address;
105	if (be32_to_cpu(dsl->sl_offset) +
106				be32_to_cpu(dsl->sl_bytes) >= XFS_SYMLINK_MAXLEN)
107		return __this_address;
108	if (dsl->sl_owner == 0)
109		return __this_address;
110	if (!xfs_log_check_lsn(mp, be64_to_cpu(dsl->sl_lsn)))
111		return __this_address;
112
113	return NULL;
114}
115
116static void
117xfs_symlink_read_verify(
118	struct xfs_buf	*bp)
119{
120	struct xfs_mount *mp = bp->b_mount;
121	xfs_failaddr_t	fa;
122
123	/* no verification of non-crc buffers */
124	if (!xfs_has_crc(mp))
125		return;
126
127	if (!xfs_buf_verify_cksum(bp, XFS_SYMLINK_CRC_OFF))
128		xfs_verifier_error(bp, -EFSBADCRC, __this_address);
129	else {
130		fa = xfs_symlink_verify(bp);
131		if (fa)
132			xfs_verifier_error(bp, -EFSCORRUPTED, fa);
133	}
134}
135
136static void
137xfs_symlink_write_verify(
138	struct xfs_buf	*bp)
139{
140	struct xfs_mount *mp = bp->b_mount;
141	struct xfs_buf_log_item	*bip = bp->b_log_item;
142	xfs_failaddr_t		fa;
143
144	/* no verification of non-crc buffers */
145	if (!xfs_has_crc(mp))
146		return;
147
148	fa = xfs_symlink_verify(bp);
149	if (fa) {
150		xfs_verifier_error(bp, -EFSCORRUPTED, fa);
151		return;
152	}
153
154	if (bip) {
155		struct xfs_dsymlink_hdr *dsl = bp->b_addr;
156		dsl->sl_lsn = cpu_to_be64(bip->bli_item.li_lsn);
157	}
158	xfs_buf_update_cksum(bp, XFS_SYMLINK_CRC_OFF);
159}
160
161const struct xfs_buf_ops xfs_symlink_buf_ops = {
162	.name = "xfs_symlink",
163	.magic = { 0, cpu_to_be32(XFS_SYMLINK_MAGIC) },
164	.verify_read = xfs_symlink_read_verify,
165	.verify_write = xfs_symlink_write_verify,
166	.verify_struct = xfs_symlink_verify,
167};
168
169void
170xfs_symlink_local_to_remote(
171	struct xfs_trans	*tp,
172	struct xfs_buf		*bp,
173	struct xfs_inode	*ip,
174	struct xfs_ifork	*ifp,
175	void			*priv)
176{
177	struct xfs_mount	*mp = ip->i_mount;
178	char			*buf;
179
180	xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
181
182	if (!xfs_has_crc(mp)) {
183		bp->b_ops = NULL;
184		memcpy(bp->b_addr, ifp->if_data, ifp->if_bytes);
185		xfs_trans_log_buf(tp, bp, 0, ifp->if_bytes - 1);
186		return;
187	}
188
189	/*
190	 * As this symlink fits in an inode literal area, it must also fit in
191	 * the smallest buffer the filesystem supports.
192	 */
193	ASSERT(BBTOB(bp->b_length) >=
194			ifp->if_bytes + sizeof(struct xfs_dsymlink_hdr));
195
196	bp->b_ops = &xfs_symlink_buf_ops;
197
198	buf = bp->b_addr;
199	buf += xfs_symlink_hdr_set(mp, ip->i_ino, 0, ifp->if_bytes, bp);
200	memcpy(buf, ifp->if_data, ifp->if_bytes);
201	xfs_trans_log_buf(tp, bp, 0, sizeof(struct xfs_dsymlink_hdr) +
202					ifp->if_bytes - 1);
203}
204
205/*
206 * Verify the in-memory consistency of an inline symlink data fork. This
207 * does not do on-disk format checks.
208 */
209xfs_failaddr_t
210xfs_symlink_shortform_verify(
211	void			*sfp,
212	int64_t			size)
213{
214	char			*endp = sfp + size;
215
216	/*
217	 * Zero length symlinks should never occur in memory as they are
218	 * never allowed to exist on disk.
219	 */
220	if (!size)
221		return __this_address;
222
223	/* No negative sizes or overly long symlink targets. */
224	if (size < 0 || size > XFS_SYMLINK_MAXLEN)
225		return __this_address;
226
227	/* No NULLs in the target either. */
228	if (memchr(sfp, 0, size - 1))
229		return __this_address;
230
231	/* We /did/ null-terminate the buffer, right? */
232	if (*endp != 0)
233		return __this_address;
234	return NULL;
235}
236
237/* Read a remote symlink target into the buffer. */
238int
239xfs_symlink_remote_read(
240	struct xfs_inode	*ip,
241	char			*link)
242{
243	struct xfs_mount	*mp = ip->i_mount;
244	struct xfs_bmbt_irec	mval[XFS_SYMLINK_MAPS];
245	struct xfs_buf		*bp;
246	xfs_daddr_t		d;
247	char			*cur_chunk;
248	int			pathlen = ip->i_disk_size;
249	int			nmaps = XFS_SYMLINK_MAPS;
250	int			byte_cnt;
251	int			n;
252	int			error = 0;
253	int			fsblocks = 0;
254	int			offset;
255
256	xfs_assert_ilocked(ip, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL);
257
258	fsblocks = xfs_symlink_blocks(mp, pathlen);
259	error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0);
260	if (error)
261		goto out;
262
263	offset = 0;
264	for (n = 0; n < nmaps; n++) {
265		d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
266		byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
267
268		error = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0,
269				&bp, &xfs_symlink_buf_ops);
270		if (xfs_metadata_is_sick(error))
271			xfs_inode_mark_sick(ip, XFS_SICK_INO_SYMLINK);
272		if (error)
273			return error;
274		byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
275		if (pathlen < byte_cnt)
276			byte_cnt = pathlen;
277
278		cur_chunk = bp->b_addr;
279		if (xfs_has_crc(mp)) {
280			if (!xfs_symlink_hdr_ok(ip->i_ino, offset,
281							byte_cnt, bp)) {
282				xfs_inode_mark_sick(ip, XFS_SICK_INO_SYMLINK);
283				error = -EFSCORRUPTED;
284				xfs_alert(mp,
285"symlink header does not match required off/len/owner (0x%x/0x%x,0x%llx)",
286					offset, byte_cnt, ip->i_ino);
287				xfs_buf_relse(bp);
288				goto out;
289
290			}
291
292			cur_chunk += sizeof(struct xfs_dsymlink_hdr);
293		}
294
295		memcpy(link + offset, cur_chunk, byte_cnt);
296
297		pathlen -= byte_cnt;
298		offset += byte_cnt;
299
300		xfs_buf_relse(bp);
301	}
302	ASSERT(pathlen == 0);
303
304	link[ip->i_disk_size] = '\0';
305	error = 0;
306
307 out:
308	return error;
309}
310
311/* Write the symlink target into the inode. */
312int
313xfs_symlink_write_target(
314	struct xfs_trans	*tp,
315	struct xfs_inode	*ip,
316	xfs_ino_t		owner,
317	const char		*target_path,
318	int			pathlen,
319	xfs_fsblock_t		fs_blocks,
320	uint			resblks)
321{
322	struct xfs_bmbt_irec	mval[XFS_SYMLINK_MAPS];
323	struct xfs_mount	*mp = tp->t_mountp;
324	const char		*cur_chunk;
325	struct xfs_buf		*bp;
326	xfs_daddr_t		d;
327	int			byte_cnt;
328	int			nmaps;
329	int			offset = 0;
330	int			n;
331	int			error;
332
333	/*
334	 * If the symlink will fit into the inode, write it inline.
335	 */
336	if (pathlen <= xfs_inode_data_fork_size(ip)) {
337		xfs_init_local_fork(ip, XFS_DATA_FORK, target_path, pathlen);
338
339		ip->i_disk_size = pathlen;
340		ip->i_df.if_format = XFS_DINODE_FMT_LOCAL;
341		xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE);
342		return 0;
343	}
344
345	nmaps = XFS_SYMLINK_MAPS;
346	error = xfs_bmapi_write(tp, ip, 0, fs_blocks, XFS_BMAPI_METADATA,
347			resblks, mval, &nmaps);
348	if (error)
349		return error;
350
351	ip->i_disk_size = pathlen;
352	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
353
354	cur_chunk = target_path;
355	offset = 0;
356	for (n = 0; n < nmaps; n++) {
357		char	*buf;
358
359		d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock);
360		byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount);
361		error = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
362				BTOBB(byte_cnt), 0, &bp);
363		if (error)
364			return error;
365		bp->b_ops = &xfs_symlink_buf_ops;
366
367		byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt);
368		byte_cnt = min(byte_cnt, pathlen);
369
370		buf = bp->b_addr;
371		buf += xfs_symlink_hdr_set(mp, owner, offset, byte_cnt, bp);
372
373		memcpy(buf, cur_chunk, byte_cnt);
374
375		cur_chunk += byte_cnt;
376		pathlen -= byte_cnt;
377		offset += byte_cnt;
378
379		xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
380		xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) -
381						(char *)bp->b_addr);
382	}
383	ASSERT(pathlen == 0);
384	return 0;
385}
386
387/* Remove all the blocks from a symlink and invalidate buffers. */
388int
389xfs_symlink_remote_truncate(
390	struct xfs_trans	*tp,
391	struct xfs_inode	*ip)
392{
393	struct xfs_bmbt_irec	mval[XFS_SYMLINK_MAPS];
394	struct xfs_mount	*mp = tp->t_mountp;
395	struct xfs_buf		*bp;
396	int			nmaps = XFS_SYMLINK_MAPS;
397	int			done = 0;
398	int			i;
399	int			error;
400
401	/* Read mappings and invalidate buffers. */
402	error = xfs_bmapi_read(ip, 0, XFS_MAX_FILEOFF, mval, &nmaps, 0);
403	if (error)
404		return error;
405
406	for (i = 0; i < nmaps; i++) {
407		if (!xfs_bmap_is_real_extent(&mval[i]))
408			break;
409
410		error = xfs_trans_get_buf(tp, mp->m_ddev_targp,
411				XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
412				XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0,
413				&bp);
414		if (error)
415			return error;
416
417		xfs_trans_binval(tp, bp);
418	}
419
420	/* Unmap the remote blocks. */
421	error = xfs_bunmapi(tp, ip, 0, XFS_MAX_FILEOFF, 0, nmaps, &done);
422	if (error)
423		return error;
424	if (!done) {
425		ASSERT(done);
426		xfs_inode_mark_sick(ip, XFS_SICK_INO_SYMLINK);
427		return -EFSCORRUPTED;
428	}
429
430	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
431	return 0;
432}