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 
20 
21 /*
22  * Each contiguous block has a header, so it is not just a simple pathlen
23  * to FSB conversion.
24  */
25 int
26 xfs_symlink_blocks(
27 	struct xfs_mount *mp,
28 	int		pathlen)
29 {
30 	int buflen = XFS_SYMLINK_BUF_SPACE(mp, mp->m_sb.sb_blocksize);
31 
32 	return (pathlen + buflen - 1) / buflen;
33 }
34 
35 int
36 xfs_symlink_hdr_set(
37 	struct xfs_mount	*mp,
38 	xfs_ino_t		ino,
39 	uint32_t		offset,
40 	uint32_t		size,
41 	struct xfs_buf		*bp)
42 {
43 	struct xfs_dsymlink_hdr	*dsl = bp->b_addr;
44 
45 	if (!xfs_sb_version_hascrc(&mp->m_sb))
46 		return 0;
47 
48 	memset(dsl, 0, sizeof(struct xfs_dsymlink_hdr));
49 	dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
50 	dsl->sl_offset = cpu_to_be32(offset);
51 	dsl->sl_bytes = cpu_to_be32(size);
52 	uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid);
53 	dsl->sl_owner = cpu_to_be64(ino);
54 	dsl->sl_blkno = cpu_to_be64(bp->b_bn);
55 	bp->b_ops = &xfs_symlink_buf_ops;
56 
57 	return sizeof(struct xfs_dsymlink_hdr);
58 }
59 
60 /*
61  * Checking of the symlink header is split into two parts. the verifier does
62  * CRC, location and bounds checking, the unpacking function checks the path
63  * parameters and owner.
64  */
65 bool
66 xfs_symlink_hdr_ok(
67 	xfs_ino_t		ino,
68 	uint32_t		offset,
69 	uint32_t		size,
70 	struct xfs_buf		*bp)
71 {
72 	struct xfs_dsymlink_hdr *dsl = bp->b_addr;
73 
74 	if (offset != be32_to_cpu(dsl->sl_offset))
75 		return false;
76 	if (size != be32_to_cpu(dsl->sl_bytes))
77 		return false;
78 	if (ino != be64_to_cpu(dsl->sl_owner))
79 		return false;
80 
81 	/* ok */
82 	return true;
83 }
84 
85 static xfs_failaddr_t
86 xfs_symlink_verify(
87 	struct xfs_buf		*bp)
88 {
89 	struct xfs_mount	*mp = bp->b_mount;
90 	struct xfs_dsymlink_hdr	*dsl = bp->b_addr;
91 
92 	if (!xfs_sb_version_hascrc(&mp->m_sb))
93 		return __this_address;
94 	if (!xfs_verify_magic(bp, dsl->sl_magic))
95 		return __this_address;
96 	if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid))
97 		return __this_address;
98 	if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
99 		return __this_address;
100 	if (be32_to_cpu(dsl->sl_offset) +
101 				be32_to_cpu(dsl->sl_bytes) >= XFS_SYMLINK_MAXLEN)
102 		return __this_address;
103 	if (dsl->sl_owner == 0)
104 		return __this_address;
105 	if (!xfs_log_check_lsn(mp, be64_to_cpu(dsl->sl_lsn)))
106 		return __this_address;
107 
108 	return NULL;
109 }
110 
111 static void
112 xfs_symlink_read_verify(
113 	struct xfs_buf	*bp)
114 {
115 	struct xfs_mount *mp = bp->b_mount;
116 	xfs_failaddr_t	fa;
117 
118 	/* no verification of non-crc buffers */
119 	if (!xfs_sb_version_hascrc(&mp->m_sb))
120 		return;
121 
122 	if (!xfs_buf_verify_cksum(bp, XFS_SYMLINK_CRC_OFF))
123 		xfs_verifier_error(bp, -EFSBADCRC, __this_address);
124 	else {
125 		fa = xfs_symlink_verify(bp);
126 		if (fa)
127 			xfs_verifier_error(bp, -EFSCORRUPTED, fa);
128 	}
129 }
130 
131 static void
132 xfs_symlink_write_verify(
133 	struct xfs_buf	*bp)
134 {
135 	struct xfs_mount *mp = bp->b_mount;
136 	struct xfs_buf_log_item	*bip = bp->b_log_item;
137 	xfs_failaddr_t		fa;
138 
139 	/* no verification of non-crc buffers */
140 	if (!xfs_sb_version_hascrc(&mp->m_sb))
141 		return;
142 
143 	fa = xfs_symlink_verify(bp);
144 	if (fa) {
145 		xfs_verifier_error(bp, -EFSCORRUPTED, fa);
146 		return;
147 	}
148 
149 	if (bip) {
150 		struct xfs_dsymlink_hdr *dsl = bp->b_addr;
151 		dsl->sl_lsn = cpu_to_be64(bip->bli_item.li_lsn);
152 	}
153 	xfs_buf_update_cksum(bp, XFS_SYMLINK_CRC_OFF);
154 }
155 
156 const struct xfs_buf_ops xfs_symlink_buf_ops = {
157 	.name = "xfs_symlink",
158 	.magic = { 0, cpu_to_be32(XFS_SYMLINK_MAGIC) },
159 	.verify_read = xfs_symlink_read_verify,
160 	.verify_write = xfs_symlink_write_verify,
161 	.verify_struct = xfs_symlink_verify,
162 };
163 
164 void
165 xfs_symlink_local_to_remote(
166 	struct xfs_trans	*tp,
167 	struct xfs_buf		*bp,
168 	struct xfs_inode	*ip,
169 	struct xfs_ifork	*ifp)
170 {
171 	struct xfs_mount	*mp = ip->i_mount;
172 	char			*buf;
173 
174 	xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
175 
176 	if (!xfs_sb_version_hascrc(&mp->m_sb)) {
177 		bp->b_ops = NULL;
178 		memcpy(bp->b_addr, ifp->if_u1.if_data, ifp->if_bytes);
179 		xfs_trans_log_buf(tp, bp, 0, ifp->if_bytes - 1);
180 		return;
181 	}
182 
183 	/*
184 	 * As this symlink fits in an inode literal area, it must also fit in
185 	 * the smallest buffer the filesystem supports.
186 	 */
187 	ASSERT(BBTOB(bp->b_length) >=
188 			ifp->if_bytes + sizeof(struct xfs_dsymlink_hdr));
189 
190 	bp->b_ops = &xfs_symlink_buf_ops;
191 
192 	buf = bp->b_addr;
193 	buf += xfs_symlink_hdr_set(mp, ip->i_ino, 0, ifp->if_bytes, bp);
194 	memcpy(buf, ifp->if_u1.if_data, ifp->if_bytes);
195 	xfs_trans_log_buf(tp, bp, 0, sizeof(struct xfs_dsymlink_hdr) +
196 					ifp->if_bytes - 1);
197 }
198 
199 /*
200  * Verify the in-memory consistency of an inline symlink data fork. This
201  * does not do on-disk format checks.
202  */
203 xfs_failaddr_t
204 xfs_symlink_shortform_verify(
205 	struct xfs_inode	*ip)
206 {
207 	struct xfs_ifork	*ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
208 	char			*sfp = (char *)ifp->if_u1.if_data;
209 	int			size = ifp->if_bytes;
210 	char			*endp = sfp + size;
211 
212 	ASSERT(ifp->if_format == XFS_DINODE_FMT_LOCAL);
213 
214 	/*
215 	 * Zero length symlinks should never occur in memory as they are
216 	 * never alllowed to exist on disk.
217 	 */
218 	if (!size)
219 		return __this_address;
220 
221 	/* No negative sizes or overly long symlink targets. */
222 	if (size < 0 || size > XFS_SYMLINK_MAXLEN)
223 		return __this_address;
224 
225 	/* No NULLs in the target either. */
226 	if (memchr(sfp, 0, size - 1))
227 		return __this_address;
228 
229 	/* We /did/ null-terminate the buffer, right? */
230 	if (*endp != 0)
231 		return __this_address;
232 	return NULL;
233 }
234