1/*
2 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
3 * Copyright (c) 2012-2013 Red Hat, Inc.
4 * All rights reserved.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it would be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write the Free Software Foundation,
17 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
18 */
19#include "xfs.h"
20#include "xfs_fs.h"
21#include "xfs_format.h"
22#include "xfs_log_format.h"
23#include "xfs_shared.h"
24#include "xfs_trans_resv.h"
25#include "xfs_mount.h"
26#include "xfs_bmap_btree.h"
27#include "xfs_inode.h"
28#include "xfs_error.h"
29#include "xfs_trace.h"
30#include "xfs_symlink.h"
31#include "xfs_cksum.h"
32#include "xfs_trans.h"
33#include "xfs_buf_item.h"
34
35
36/*
37 * Each contiguous block has a header, so it is not just a simple pathlen
38 * to FSB conversion.
39 */
40int
41xfs_symlink_blocks(
42	struct xfs_mount *mp,
43	int		pathlen)
44{
45	int buflen = XFS_SYMLINK_BUF_SPACE(mp, mp->m_sb.sb_blocksize);
46
47	return (pathlen + buflen - 1) / buflen;
48}
49
50int
51xfs_symlink_hdr_set(
52	struct xfs_mount	*mp,
53	xfs_ino_t		ino,
54	uint32_t		offset,
55	uint32_t		size,
56	struct xfs_buf		*bp)
57{
58	struct xfs_dsymlink_hdr	*dsl = bp->b_addr;
59
60	if (!xfs_sb_version_hascrc(&mp->m_sb))
61		return 0;
62
63	dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
64	dsl->sl_offset = cpu_to_be32(offset);
65	dsl->sl_bytes = cpu_to_be32(size);
66	uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_uuid);
67	dsl->sl_owner = cpu_to_be64(ino);
68	dsl->sl_blkno = cpu_to_be64(bp->b_bn);
69	bp->b_ops = &xfs_symlink_buf_ops;
70
71	return sizeof(struct xfs_dsymlink_hdr);
72}
73
74/*
75 * Checking of the symlink header is split into two parts. the verifier does
76 * CRC, location and bounds checking, the unpacking function checks the path
77 * parameters and owner.
78 */
79bool
80xfs_symlink_hdr_ok(
81	xfs_ino_t		ino,
82	uint32_t		offset,
83	uint32_t		size,
84	struct xfs_buf		*bp)
85{
86	struct xfs_dsymlink_hdr *dsl = bp->b_addr;
87
88	if (offset != be32_to_cpu(dsl->sl_offset))
89		return false;
90	if (size != be32_to_cpu(dsl->sl_bytes))
91		return false;
92	if (ino != be64_to_cpu(dsl->sl_owner))
93		return false;
94
95	/* ok */
96	return true;
97}
98
99static bool
100xfs_symlink_verify(
101	struct xfs_buf		*bp)
102{
103	struct xfs_mount	*mp = bp->b_target->bt_mount;
104	struct xfs_dsymlink_hdr	*dsl = bp->b_addr;
105
106	if (!xfs_sb_version_hascrc(&mp->m_sb))
107		return false;
108	if (dsl->sl_magic != cpu_to_be32(XFS_SYMLINK_MAGIC))
109		return false;
110	if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_uuid))
111		return false;
112	if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
113		return false;
114	if (be32_to_cpu(dsl->sl_offset) +
115				be32_to_cpu(dsl->sl_bytes) >= MAXPATHLEN)
116		return false;
117	if (dsl->sl_owner == 0)
118		return false;
119
120	return true;
121}
122
123static void
124xfs_symlink_read_verify(
125	struct xfs_buf	*bp)
126{
127	struct xfs_mount *mp = bp->b_target->bt_mount;
128
129	/* no verification of non-crc buffers */
130	if (!xfs_sb_version_hascrc(&mp->m_sb))
131		return;
132
133	if (!xfs_buf_verify_cksum(bp, XFS_SYMLINK_CRC_OFF))
134		xfs_buf_ioerror(bp, -EFSBADCRC);
135	else if (!xfs_symlink_verify(bp))
136		xfs_buf_ioerror(bp, -EFSCORRUPTED);
137
138	if (bp->b_error)
139		xfs_verifier_error(bp);
140}
141
142static void
143xfs_symlink_write_verify(
144	struct xfs_buf	*bp)
145{
146	struct xfs_mount *mp = bp->b_target->bt_mount;
147	struct xfs_buf_log_item	*bip = bp->b_fspriv;
148
149	/* no verification of non-crc buffers */
150	if (!xfs_sb_version_hascrc(&mp->m_sb))
151		return;
152
153	if (!xfs_symlink_verify(bp)) {
154		xfs_buf_ioerror(bp, -EFSCORRUPTED);
155		xfs_verifier_error(bp);
156		return;
157	}
158
159	if (bip) {
160		struct xfs_dsymlink_hdr *dsl = bp->b_addr;
161		dsl->sl_lsn = cpu_to_be64(bip->bli_item.li_lsn);
162	}
163	xfs_buf_update_cksum(bp, XFS_SYMLINK_CRC_OFF);
164}
165
166const struct xfs_buf_ops xfs_symlink_buf_ops = {
167	.verify_read = xfs_symlink_read_verify,
168	.verify_write = xfs_symlink_write_verify,
169};
170
171void
172xfs_symlink_local_to_remote(
173	struct xfs_trans	*tp,
174	struct xfs_buf		*bp,
175	struct xfs_inode	*ip,
176	struct xfs_ifork	*ifp)
177{
178	struct xfs_mount	*mp = ip->i_mount;
179	char			*buf;
180
181	xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
182
183	if (!xfs_sb_version_hascrc(&mp->m_sb)) {
184		bp->b_ops = NULL;
185		memcpy(bp->b_addr, ifp->if_u1.if_data, ifp->if_bytes);
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_u1.if_data, ifp->if_bytes);
201}
202