xref: /linux/fs/xfs/libxfs/xfs_symlink_remote.c (revision e5c86679d5e864947a52fb31e45a425dea3e7fa9)
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 #include "xfs_log.h"
35 
36 
37 /*
38  * Each contiguous block has a header, so it is not just a simple pathlen
39  * to FSB conversion.
40  */
41 int
42 xfs_symlink_blocks(
43 	struct xfs_mount *mp,
44 	int		pathlen)
45 {
46 	int buflen = XFS_SYMLINK_BUF_SPACE(mp, mp->m_sb.sb_blocksize);
47 
48 	return (pathlen + buflen - 1) / buflen;
49 }
50 
51 int
52 xfs_symlink_hdr_set(
53 	struct xfs_mount	*mp,
54 	xfs_ino_t		ino,
55 	uint32_t		offset,
56 	uint32_t		size,
57 	struct xfs_buf		*bp)
58 {
59 	struct xfs_dsymlink_hdr	*dsl = bp->b_addr;
60 
61 	if (!xfs_sb_version_hascrc(&mp->m_sb))
62 		return 0;
63 
64 	memset(dsl, 0, sizeof(struct xfs_dsymlink_hdr));
65 	dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
66 	dsl->sl_offset = cpu_to_be32(offset);
67 	dsl->sl_bytes = cpu_to_be32(size);
68 	uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid);
69 	dsl->sl_owner = cpu_to_be64(ino);
70 	dsl->sl_blkno = cpu_to_be64(bp->b_bn);
71 	bp->b_ops = &xfs_symlink_buf_ops;
72 
73 	return sizeof(struct xfs_dsymlink_hdr);
74 }
75 
76 /*
77  * Checking of the symlink header is split into two parts. the verifier does
78  * CRC, location and bounds checking, the unpacking function checks the path
79  * parameters and owner.
80  */
81 bool
82 xfs_symlink_hdr_ok(
83 	xfs_ino_t		ino,
84 	uint32_t		offset,
85 	uint32_t		size,
86 	struct xfs_buf		*bp)
87 {
88 	struct xfs_dsymlink_hdr *dsl = bp->b_addr;
89 
90 	if (offset != be32_to_cpu(dsl->sl_offset))
91 		return false;
92 	if (size != be32_to_cpu(dsl->sl_bytes))
93 		return false;
94 	if (ino != be64_to_cpu(dsl->sl_owner))
95 		return false;
96 
97 	/* ok */
98 	return true;
99 }
100 
101 static bool
102 xfs_symlink_verify(
103 	struct xfs_buf		*bp)
104 {
105 	struct xfs_mount	*mp = bp->b_target->bt_mount;
106 	struct xfs_dsymlink_hdr	*dsl = bp->b_addr;
107 
108 	if (!xfs_sb_version_hascrc(&mp->m_sb))
109 		return false;
110 	if (dsl->sl_magic != cpu_to_be32(XFS_SYMLINK_MAGIC))
111 		return false;
112 	if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid))
113 		return false;
114 	if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
115 		return false;
116 	if (be32_to_cpu(dsl->sl_offset) +
117 				be32_to_cpu(dsl->sl_bytes) >= MAXPATHLEN)
118 		return false;
119 	if (dsl->sl_owner == 0)
120 		return false;
121 	if (!xfs_log_check_lsn(mp, be64_to_cpu(dsl->sl_lsn)))
122 		return false;
123 
124 	return true;
125 }
126 
127 static void
128 xfs_symlink_read_verify(
129 	struct xfs_buf	*bp)
130 {
131 	struct xfs_mount *mp = bp->b_target->bt_mount;
132 
133 	/* no verification of non-crc buffers */
134 	if (!xfs_sb_version_hascrc(&mp->m_sb))
135 		return;
136 
137 	if (!xfs_buf_verify_cksum(bp, XFS_SYMLINK_CRC_OFF))
138 		xfs_buf_ioerror(bp, -EFSBADCRC);
139 	else if (!xfs_symlink_verify(bp))
140 		xfs_buf_ioerror(bp, -EFSCORRUPTED);
141 
142 	if (bp->b_error)
143 		xfs_verifier_error(bp);
144 }
145 
146 static void
147 xfs_symlink_write_verify(
148 	struct xfs_buf	*bp)
149 {
150 	struct xfs_mount *mp = bp->b_target->bt_mount;
151 	struct xfs_buf_log_item	*bip = bp->b_fspriv;
152 
153 	/* no verification of non-crc buffers */
154 	if (!xfs_sb_version_hascrc(&mp->m_sb))
155 		return;
156 
157 	if (!xfs_symlink_verify(bp)) {
158 		xfs_buf_ioerror(bp, -EFSCORRUPTED);
159 		xfs_verifier_error(bp);
160 		return;
161 	}
162 
163 	if (bip) {
164 		struct xfs_dsymlink_hdr *dsl = bp->b_addr;
165 		dsl->sl_lsn = cpu_to_be64(bip->bli_item.li_lsn);
166 	}
167 	xfs_buf_update_cksum(bp, XFS_SYMLINK_CRC_OFF);
168 }
169 
170 const struct xfs_buf_ops xfs_symlink_buf_ops = {
171 	.name = "xfs_symlink",
172 	.verify_read = xfs_symlink_read_verify,
173 	.verify_write = xfs_symlink_write_verify,
174 };
175 
176 void
177 xfs_symlink_local_to_remote(
178 	struct xfs_trans	*tp,
179 	struct xfs_buf		*bp,
180 	struct xfs_inode	*ip,
181 	struct xfs_ifork	*ifp)
182 {
183 	struct xfs_mount	*mp = ip->i_mount;
184 	char			*buf;
185 
186 	xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
187 
188 	if (!xfs_sb_version_hascrc(&mp->m_sb)) {
189 		bp->b_ops = NULL;
190 		memcpy(bp->b_addr, ifp->if_u1.if_data, ifp->if_bytes);
191 		xfs_trans_log_buf(tp, bp, 0, ifp->if_bytes - 1);
192 		return;
193 	}
194 
195 	/*
196 	 * As this symlink fits in an inode literal area, it must also fit in
197 	 * the smallest buffer the filesystem supports.
198 	 */
199 	ASSERT(BBTOB(bp->b_length) >=
200 			ifp->if_bytes + sizeof(struct xfs_dsymlink_hdr));
201 
202 	bp->b_ops = &xfs_symlink_buf_ops;
203 
204 	buf = bp->b_addr;
205 	buf += xfs_symlink_hdr_set(mp, ip->i_ino, 0, ifp->if_bytes, bp);
206 	memcpy(buf, ifp->if_u1.if_data, ifp->if_bytes);
207 	xfs_trans_log_buf(tp, bp, 0, sizeof(struct xfs_dsymlink_hdr) +
208 					ifp->if_bytes - 1);
209 }
210