1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* CacheFiles extended attribute management
3 *
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8 #include <linux/module.h>
9 #include <linux/sched.h>
10 #include <linux/file.h>
11 #include <linux/fs.h>
12 #include <linux/fsnotify.h>
13 #include <linux/quotaops.h>
14 #include <linux/xattr.h>
15 #include <linux/slab.h>
16 #include "internal.h"
17
18 static const char cachefiles_xattr_cache[] =
19 XATTR_USER_PREFIX "CacheFiles.cache";
20
21 /*
22 * check the type label on an object
23 * - done using xattrs
24 */
cachefiles_check_object_type(struct cachefiles_object * object)25 int cachefiles_check_object_type(struct cachefiles_object *object)
26 {
27 struct dentry *dentry = object->dentry;
28 char type[3], xtype[3];
29 int ret;
30
31 ASSERT(dentry);
32 ASSERT(d_backing_inode(dentry));
33
34 if (!object->fscache.cookie)
35 strcpy(type, "C3");
36 else
37 snprintf(type, 3, "%02x", object->fscache.cookie->def->type);
38
39 _enter("%p{%s}", object, type);
40
41 /* attempt to install a type label directly */
42 ret = vfs_setxattr(dentry, cachefiles_xattr_cache, type, 2,
43 XATTR_CREATE);
44 if (ret == 0) {
45 _debug("SET"); /* we succeeded */
46 goto error;
47 }
48
49 if (ret != -EEXIST) {
50 pr_err("Can't set xattr on %pd [%lu] (err %d)\n",
51 dentry, d_backing_inode(dentry)->i_ino,
52 -ret);
53 goto error;
54 }
55
56 /* read the current type label */
57 ret = vfs_getxattr(dentry, cachefiles_xattr_cache, xtype, 3);
58 if (ret < 0) {
59 if (ret == -ERANGE)
60 goto bad_type_length;
61
62 pr_err("Can't read xattr on %pd [%lu] (err %d)\n",
63 dentry, d_backing_inode(dentry)->i_ino,
64 -ret);
65 goto error;
66 }
67
68 /* check the type is what we're expecting */
69 if (ret != 2)
70 goto bad_type_length;
71
72 if (xtype[0] != type[0] || xtype[1] != type[1])
73 goto bad_type;
74
75 ret = 0;
76
77 error:
78 _leave(" = %d", ret);
79 return ret;
80
81 bad_type_length:
82 pr_err("Cache object %lu type xattr length incorrect\n",
83 d_backing_inode(dentry)->i_ino);
84 ret = -EIO;
85 goto error;
86
87 bad_type:
88 xtype[2] = 0;
89 pr_err("Cache object %pd [%lu] type %s not %s\n",
90 dentry, d_backing_inode(dentry)->i_ino,
91 xtype, type);
92 ret = -EIO;
93 goto error;
94 }
95
96 /*
97 * set the state xattr on a cache file
98 */
cachefiles_set_object_xattr(struct cachefiles_object * object,struct cachefiles_xattr * auxdata)99 int cachefiles_set_object_xattr(struct cachefiles_object *object,
100 struct cachefiles_xattr *auxdata)
101 {
102 struct dentry *dentry = object->dentry;
103 int ret;
104
105 ASSERT(dentry);
106
107 _enter("%p,#%d", object, auxdata->len);
108
109 /* attempt to install the cache metadata directly */
110 _debug("SET #%u", auxdata->len);
111
112 clear_bit(FSCACHE_COOKIE_AUX_UPDATED, &object->fscache.cookie->flags);
113 ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
114 &auxdata->type, auxdata->len,
115 XATTR_CREATE);
116 if (ret < 0 && ret != -ENOMEM)
117 cachefiles_io_error_obj(
118 object,
119 "Failed to set xattr with error %d", ret);
120
121 _leave(" = %d", ret);
122 return ret;
123 }
124
125 /*
126 * update the state xattr on a cache file
127 */
cachefiles_update_object_xattr(struct cachefiles_object * object,struct cachefiles_xattr * auxdata)128 int cachefiles_update_object_xattr(struct cachefiles_object *object,
129 struct cachefiles_xattr *auxdata)
130 {
131 struct dentry *dentry = object->dentry;
132 int ret;
133
134 if (!dentry)
135 return -ESTALE;
136
137 _enter("%p,#%d", object, auxdata->len);
138
139 /* attempt to install the cache metadata directly */
140 _debug("SET #%u", auxdata->len);
141
142 clear_bit(FSCACHE_COOKIE_AUX_UPDATED, &object->fscache.cookie->flags);
143 ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
144 &auxdata->type, auxdata->len,
145 XATTR_REPLACE);
146 if (ret < 0 && ret != -ENOMEM)
147 cachefiles_io_error_obj(
148 object,
149 "Failed to update xattr with error %d", ret);
150
151 _leave(" = %d", ret);
152 return ret;
153 }
154
155 /*
156 * check the consistency between the backing cache and the FS-Cache cookie
157 */
cachefiles_check_auxdata(struct cachefiles_object * object)158 int cachefiles_check_auxdata(struct cachefiles_object *object)
159 {
160 struct cachefiles_xattr *auxbuf;
161 enum fscache_checkaux validity;
162 struct dentry *dentry = object->dentry;
163 ssize_t xlen;
164 int ret;
165
166 ASSERT(dentry);
167 ASSERT(d_backing_inode(dentry));
168 ASSERT(object->fscache.cookie->def->check_aux);
169
170 auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, GFP_KERNEL);
171 if (!auxbuf)
172 return -ENOMEM;
173
174 xlen = vfs_getxattr(dentry, cachefiles_xattr_cache,
175 &auxbuf->type, 512 + 1);
176 ret = -ESTALE;
177 if (xlen < 1 ||
178 auxbuf->type != object->fscache.cookie->def->type)
179 goto error;
180
181 xlen--;
182 validity = fscache_check_aux(&object->fscache, &auxbuf->data, xlen,
183 i_size_read(d_backing_inode(dentry)));
184 if (validity != FSCACHE_CHECKAUX_OKAY)
185 goto error;
186
187 ret = 0;
188 error:
189 kfree(auxbuf);
190 return ret;
191 }
192
193 /*
194 * check the state xattr on a cache file
195 * - return -ESTALE if the object should be deleted
196 */
cachefiles_check_object_xattr(struct cachefiles_object * object,struct cachefiles_xattr * auxdata)197 int cachefiles_check_object_xattr(struct cachefiles_object *object,
198 struct cachefiles_xattr *auxdata)
199 {
200 struct cachefiles_xattr *auxbuf;
201 struct dentry *dentry = object->dentry;
202 int ret;
203
204 _enter("%p,#%d", object, auxdata->len);
205
206 ASSERT(dentry);
207 ASSERT(d_backing_inode(dentry));
208
209 auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, cachefiles_gfp);
210 if (!auxbuf) {
211 _leave(" = -ENOMEM");
212 return -ENOMEM;
213 }
214
215 /* read the current type label */
216 ret = vfs_getxattr(dentry, cachefiles_xattr_cache,
217 &auxbuf->type, 512 + 1);
218 if (ret < 0) {
219 if (ret == -ENODATA)
220 goto stale; /* no attribute - power went off
221 * mid-cull? */
222
223 if (ret == -ERANGE)
224 goto bad_type_length;
225
226 cachefiles_io_error_obj(object,
227 "Can't read xattr on %lu (err %d)",
228 d_backing_inode(dentry)->i_ino, -ret);
229 goto error;
230 }
231
232 /* check the on-disk object */
233 if (ret < 1)
234 goto bad_type_length;
235
236 if (auxbuf->type != auxdata->type)
237 goto stale;
238
239 auxbuf->len = ret;
240
241 /* consult the netfs */
242 if (object->fscache.cookie->def->check_aux) {
243 enum fscache_checkaux result;
244 unsigned int dlen;
245
246 dlen = auxbuf->len - 1;
247
248 _debug("checkaux %s #%u",
249 object->fscache.cookie->def->name, dlen);
250
251 result = fscache_check_aux(&object->fscache,
252 &auxbuf->data, dlen,
253 i_size_read(d_backing_inode(dentry)));
254
255 switch (result) {
256 /* entry okay as is */
257 case FSCACHE_CHECKAUX_OKAY:
258 goto okay;
259
260 /* entry requires update */
261 case FSCACHE_CHECKAUX_NEEDS_UPDATE:
262 break;
263
264 /* entry requires deletion */
265 case FSCACHE_CHECKAUX_OBSOLETE:
266 goto stale;
267
268 default:
269 BUG();
270 }
271
272 /* update the current label */
273 ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
274 &auxdata->type, auxdata->len,
275 XATTR_REPLACE);
276 if (ret < 0) {
277 cachefiles_io_error_obj(object,
278 "Can't update xattr on %lu"
279 " (error %d)",
280 d_backing_inode(dentry)->i_ino, -ret);
281 goto error;
282 }
283 }
284
285 okay:
286 ret = 0;
287
288 error:
289 kfree(auxbuf);
290 _leave(" = %d", ret);
291 return ret;
292
293 bad_type_length:
294 pr_err("Cache object %lu xattr length incorrect\n",
295 d_backing_inode(dentry)->i_ino);
296 ret = -EIO;
297 goto error;
298
299 stale:
300 ret = -ESTALE;
301 goto error;
302 }
303
304 /*
305 * remove the object's xattr to mark it stale
306 */
cachefiles_remove_object_xattr(struct cachefiles_cache * cache,struct dentry * dentry)307 int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
308 struct dentry *dentry)
309 {
310 int ret;
311
312 ret = vfs_removexattr(dentry, cachefiles_xattr_cache);
313 if (ret < 0) {
314 if (ret == -ENOENT || ret == -ENODATA)
315 ret = 0;
316 else if (ret != -ENOMEM)
317 cachefiles_io_error(cache,
318 "Can't remove xattr from %lu"
319 " (error %d)",
320 d_backing_inode(dentry)->i_ino, -ret);
321 }
322
323 _leave(" = %d", ret);
324 return ret;
325 }
326