summaryrefslogtreecommitdiffstats
path: root/fs/squashfs/xattr.c
blob: 2f0ccbaa2d9230cd0e183ca7ef15e4142ce5cc0a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
/*
 * Squashfs - a compressed read only filesystem for Linux
 *
 * Copyright (c) 2010
 * Phillip Lougher <phillip@squashfs.org.uk>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2,
 * or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * xattr.c
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/vfs.h>
#include <linux/xattr.h>
#include <linux/slab.h>

#include "squashfs_fs.h"
#include "squashfs_fs_sb.h"
#include "squashfs_fs_i.h"
#include "squashfs.h"

static const struct xattr_handler *squashfs_xattr_handler(int);

ssize_t squashfs_listxattr(struct dentry *d, char *buffer,
	size_t buffer_size)
{
	struct inode *inode = d_inode(d);
	struct super_block *sb = inode->i_sb;
	struct squashfs_sb_info *msblk = sb->s_fs_info;
	u64 start = SQUASHFS_XATTR_BLK(squashfs_i(inode)->xattr)
						 + msblk->xattr_table;
	int offset = SQUASHFS_XATTR_OFFSET(squashfs_i(inode)->xattr);
	int count = squashfs_i(inode)->xattr_count;
	size_t rest = buffer_size;
	int err;

	/* check that the file system has xattrs */
	if (msblk->xattr_id_table == NULL)
		return -EOPNOTSUPP;

	/* loop reading each xattr name */
	while (count--) {
		struct squashfs_xattr_entry entry;
		struct squashfs_xattr_val val;
		const struct xattr_handler *handler;
		int name_size, prefix_size = 0;

		err = squashfs_read_metadata(sb, &entry, &start, &offset,
							sizeof(entry));
		if (err < 0)
			goto failed;

		name_size = le16_to_cpu(entry.size);
		handler = squashfs_xattr_handler(le16_to_cpu(entry.type));
		if (handler)
			prefix_size = handler->list(handler, d, buffer, rest,
						    NULL, name_size);
		if (prefix_size) {
			if (buffer) {
				if (prefix_size + name_size + 1 > rest) {
					err = -ERANGE;
					goto failed;
				}
				buffer += prefix_size;
			}
			err = squashfs_read_metadata(sb, buffer, &start,
				&offset, name_size);
			if (err < 0)
				goto failed;
			if (buffer) {
				buffer[name_size] = '\0';
				buffer += name_size + 1;
			}
			rest -= prefix_size + name_size + 1;
		} else  {
			/* no handler or insuffficient privileges, so skip */
			err = squashfs_read_metadata(sb, NULL, &start,
				&offset, name_size);
			if (err < 0)
				goto failed;
		}


		/* skip remaining xattr entry */
		err = squashfs_read_metadata(sb, &val, &start, &offset,
						sizeof(val));
		if (err < 0)
			goto failed;

		err = squashfs_read_metadata(sb, NULL, &start, &offset,
						le32_to_cpu(val.vsize));
		if (err < 0)
			goto failed;
	}
	err = buffer_size - rest;

failed:
	return err;
}


static int squashfs_xattr_get(struct inode *inode, int name_index,
	const char *name, void *buffer, size_t buffer_size)
{
	struct super_block *sb = inode->i_sb;
	struct squashfs_sb_info *msblk = sb->s_fs_info;
	u64 start = SQUASHFS_XATTR_BLK(squashfs_i(inode)->xattr)
						 + msblk->xattr_table;
	int offset = SQUASHFS_XATTR_OFFSET(squashfs_i(inode)->xattr);
	int count = squashfs_i(inode)->xattr_count;
	int name_len = strlen(name);
	int err, vsize;
	char *target = kmalloc(name_len, GFP_KERNEL);

	if (target == NULL)
		return  -ENOMEM;

	/* loop reading each xattr name */
	for (; count; count--) {
		struct squashfs_xattr_entry entry;
		struct squashfs_xattr_val val;
		int type, prefix, name_size;

		err = squashfs_read_metadata(sb, &entry, &start, &offset,
							sizeof(entry));
		if (err < 0)
			goto failed;

		name_size = le16_to_cpu(entry.size);
		type = le16_to_cpu(entry.type);
		prefix = type & SQUASHFS_XATTR_PREFIX_MASK;

		if (prefix == name_index && name_size == name_len)
			err = squashfs_read_metadata(sb, target, &start,
						&offset, name_size);
		else
			err = squashfs_read_metadata(sb, NULL, &start,
						&offset, name_size);
		if (err < 0)
			goto failed;

		if (prefix == name_index && name_size == name_len &&
					strncmp(target, name, name_size) == 0) {
			/* found xattr */
			if (type & SQUASHFS_XATTR_VALUE_OOL) {
				__le64 xattr_val;
				u64 xattr;
				/* val is a reference to the real location */
				err = squashfs_read_metadata(sb, &val, &start,
						&offset, sizeof(val));
				if (err < 0)
					goto failed;
				err = squashfs_read_metadata(sb, &xattr_val,
					&start, &offset, sizeof(xattr_val));
				if (err < 0)
					goto failed;
				xattr = le64_to_cpu(xattr_val);
				start = SQUASHFS_XATTR_BLK(xattr) +
							msblk->xattr_table;
				offset = SQUASHFS_XATTR_OFFSET(xattr);
			}
			/* read xattr value */
			err = squashfs_read_metadata(sb, &val, &start, &offset,
							sizeof(val));
			if (err < 0)
				goto failed;

			vsize = le32_to_cpu(val.vsize);
			if (buffer) {
				if (vsize > buffer_size) {
					err = -ERANGE;
					goto failed;
				}
				err = squashfs_read_metadata(sb, buffer, &start,
					 &offset, vsize);
				if (err < 0)
					goto failed;
			}
			break;
		}

		/* no match, skip remaining xattr entry */
		err = squashfs_read_metadata(sb, &val, &start, &offset,
							sizeof(val));
		if (err < 0)
			goto failed;
		err = squashfs_read_metadata(sb, NULL, &start, &offset,
						le32_to_cpu(val.vsize));
		if (err < 0)
			goto failed;
	}
	err = count ? vsize : -ENODATA;

failed:
	kfree(target);
	return err;
}


static size_t squashfs_xattr_handler_list(const struct xattr_handler *handler,
					  struct dentry *d, char *list,
					  size_t list_size, const char *name,
					  size_t name_len)
{
	int len = strlen(handler->prefix);

	if (list && len <= list_size)
		memcpy(list, handler->prefix, len);
	return len;
}

static int squashfs_xattr_handler_get(const struct xattr_handler *handler,
				      struct dentry *d, const char *name,
				      void *buffer, size_t size)
{
	return squashfs_xattr_get(d_inode(d), handler->flags, name,
		buffer, size);
}

/*
 * User namespace support
 */
static const struct xattr_handler squashfs_xattr_user_handler = {
	.prefix	= XATTR_USER_PREFIX,
	.flags	= SQUASHFS_XATTR_USER,
	.list	= squashfs_xattr_handler_list,
	.get	= squashfs_xattr_handler_get
};

/*
 * Trusted namespace support
 */
static size_t squashfs_trusted_xattr_handler_list(const struct xattr_handler *handler,
						  struct dentry *d, char *list,
						  size_t list_size, const char *name,
						  size_t name_len)
{
	if (!capable(CAP_SYS_ADMIN))
		return 0;
	return squashfs_xattr_handler_list(handler, d, list, list_size, name,
					   name_len);
}

static const struct xattr_handler squashfs_xattr_trusted_handler = {
	.prefix	= XATTR_TRUSTED_PREFIX,
	.flags	= SQUASHFS_XATTR_TRUSTED,
	.list	= squashfs_trusted_xattr_handler_list,
	.get	= squashfs_xattr_handler_get
};

/*
 * Security namespace support
 */
static const struct xattr_handler squashfs_xattr_security_handler = {
	.prefix	= XATTR_SECURITY_PREFIX,
	.flags	= SQUASHFS_XATTR_SECURITY,
	.list	= squashfs_xattr_handler_list,
	.get	= squashfs_xattr_handler_get
};

static const struct xattr_handler *squashfs_xattr_handler(int type)
{
	if (type & ~(SQUASHFS_XATTR_PREFIX_MASK | SQUASHFS_XATTR_VALUE_OOL))
		/* ignore unrecognised type */
		return NULL;

	switch (type & SQUASHFS_XATTR_PREFIX_MASK) {
	case SQUASHFS_XATTR_USER:
		return &squashfs_xattr_user_handler;
	case SQUASHFS_XATTR_TRUSTED:
		return &squashfs_xattr_trusted_handler;
	case SQUASHFS_XATTR_SECURITY:
		return &squashfs_xattr_security_handler;
	default:
		/* ignore unrecognised type */
		return NULL;
	}
}

const struct xattr_handler *squashfs_xattr_handlers[] = {
	&squashfs_xattr_user_handler,
	&squashfs_xattr_trusted_handler,
	&squashfs_xattr_security_handler,
	NULL
};

OpenPOWER on IntegriCloud