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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* CacheFiles extended attribute management
3 *
4 * Copyright (C) 2021 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#define CACHEFILES_COOKIE_TYPE_DATA 1
19
20struct cachefiles_xattr {
21 __be64 object_size; /* Actual size of the object */
22 __be64 zero_point; /* Size after which server has no data not written by us */
23 __u8 type; /* Type of object */
24 __u8 content; /* Content presence (enum cachefiles_content) */
25 __u8 data[]; /* netfs coherency data */
26} __packed;
27
28static const char cachefiles_xattr_cache[] =
29 XATTR_USER_PREFIX "CacheFiles.cache";
30
31struct cachefiles_vol_xattr {
32 __be32 reserved; /* Reserved, should be 0 */
33 __u8 data[]; /* netfs volume coherency data */
34} __packed;
35
36/*
37 * set the state xattr on a cache file
38 */
39int cachefiles_set_object_xattr(struct cachefiles_object *object)
40{
41 struct cachefiles_xattr *buf;
42 struct dentry *dentry;
43 struct file *file = object->file;
44 unsigned int len = object->cookie->aux_len;
45 int ret;
46
47 if (!file)
48 return -ESTALE;
49 dentry = file->f_path.dentry;
50
51 _enter("%x,#%d", object->debug_id, len);
52
53 buf = kmalloc(sizeof(struct cachefiles_xattr) + len, GFP_KERNEL);
54 if (!buf)
55 return -ENOMEM;
56
57 buf->object_size = cpu_to_be64(object->cookie->object_size);
58 buf->zero_point = 0;
59 buf->type = CACHEFILES_COOKIE_TYPE_DATA;
60 buf->content = object->content_info;
61 if (test_bit(FSCACHE_COOKIE_LOCAL_WRITE, &object->cookie->flags))
62 buf->content = CACHEFILES_CONTENT_DIRTY;
63 if (len > 0)
64 memcpy(buf->data, fscache_get_aux(object->cookie), len);
65
66 ret = cachefiles_inject_write_error();
67 if (ret == 0)
68 ret = vfs_setxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache,
69 buf, sizeof(struct cachefiles_xattr) + len, 0);
70 if (ret < 0) {
71 trace_cachefiles_vfs_error(object, file_inode(file), ret,
72 cachefiles_trace_setxattr_error);
73 trace_cachefiles_coherency(object, file_inode(file)->i_ino,
74 buf->content,
75 cachefiles_coherency_set_fail);
76 if (ret != -ENOMEM)
77 cachefiles_io_error_obj(
78 object,
79 "Failed to set xattr with error %d", ret);
80 } else {
81 trace_cachefiles_coherency(object, file_inode(file)->i_ino,
82 buf->content,
83 cachefiles_coherency_set_ok);
84 }
85
86 kfree(buf);
87 _leave(" = %d", ret);
88 return ret;
89}
90
91/*
92 * check the consistency between the backing cache and the FS-Cache cookie
93 */
94int cachefiles_check_auxdata(struct cachefiles_object *object, struct file *file)
95{
96 struct cachefiles_xattr *buf;
97 struct dentry *dentry = file->f_path.dentry;
98 unsigned int len = object->cookie->aux_len, tlen;
99 const void *p = fscache_get_aux(object->cookie);
100 enum cachefiles_coherency_trace why;
101 ssize_t xlen;
102 int ret = -ESTALE;
103
104 tlen = sizeof(struct cachefiles_xattr) + len;
105 buf = kmalloc(tlen, GFP_KERNEL);
106 if (!buf)
107 return -ENOMEM;
108
109 xlen = cachefiles_inject_read_error();
110 if (xlen == 0)
111 xlen = vfs_getxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, buf, tlen);
112 if (xlen != tlen) {
113 if (xlen < 0)
114 trace_cachefiles_vfs_error(object, file_inode(file), xlen,
115 cachefiles_trace_getxattr_error);
116 if (xlen == -EIO)
117 cachefiles_io_error_obj(
118 object,
119 "Failed to read aux with error %zd", xlen);
120 why = cachefiles_coherency_check_xattr;
121 } else if (buf->type != CACHEFILES_COOKIE_TYPE_DATA) {
122 why = cachefiles_coherency_check_type;
123 } else if (memcmp(buf->data, p, len) != 0) {
124 why = cachefiles_coherency_check_aux;
125 } else if (be64_to_cpu(buf->object_size) != object->cookie->object_size) {
126 why = cachefiles_coherency_check_objsize;
127 } else if (buf->content == CACHEFILES_CONTENT_DIRTY) {
128 // TODO: Begin conflict resolution
129 pr_warn("Dirty object in cache\n");
130 why = cachefiles_coherency_check_dirty;
131 } else {
132 why = cachefiles_coherency_check_ok;
133 ret = 0;
134 }
135
136 trace_cachefiles_coherency(object, file_inode(file)->i_ino,
137 buf->content, why);
138 kfree(buf);
139 return ret;
140}
141
142/*
143 * remove the object's xattr to mark it stale
144 */
145int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
146 struct cachefiles_object *object,
147 struct dentry *dentry)
148{
149 int ret;
150
151 ret = cachefiles_inject_remove_error();
152 if (ret == 0)
153 ret = vfs_removexattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache);
154 if (ret < 0) {
155 trace_cachefiles_vfs_error(object, d_inode(dentry), ret,
156 cachefiles_trace_remxattr_error);
157 if (ret == -ENOENT || ret == -ENODATA)
158 ret = 0;
159 else if (ret != -ENOMEM)
160 cachefiles_io_error(cache,
161 "Can't remove xattr from %lu"
162 " (error %d)",
163 d_backing_inode(dentry)->i_ino, -ret);
164 }
165
166 _leave(" = %d", ret);
167 return ret;
168}
169
170/*
171 * Stick a marker on the cache object to indicate that it's dirty.
172 */
173void cachefiles_prepare_to_write(struct fscache_cookie *cookie)
174{
175 const struct cred *saved_cred;
176 struct cachefiles_object *object = cookie->cache_priv;
177 struct cachefiles_cache *cache = object->volume->cache;
178
179 _enter("c=%08x", object->cookie->debug_id);
180
181 if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) {
182 cachefiles_begin_secure(cache, &saved_cred);
183 cachefiles_set_object_xattr(object);
184 cachefiles_end_secure(cache, saved_cred);
185 }
186}
187
188/*
189 * Set the state xattr on a volume directory.
190 */
191bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume)
192{
193 struct cachefiles_vol_xattr *buf;
194 unsigned int len = volume->vcookie->coherency_len;
195 const void *p = volume->vcookie->coherency;
196 struct dentry *dentry = volume->dentry;
197 int ret;
198
199 _enter("%x,#%d", volume->vcookie->debug_id, len);
200
201 len += sizeof(*buf);
202 buf = kmalloc(len, GFP_KERNEL);
203 if (!buf)
204 return false;
205 buf->reserved = cpu_to_be32(0);
206 memcpy(buf->data, p, volume->vcookie->coherency_len);
207
208 ret = cachefiles_inject_write_error();
209 if (ret == 0)
210 ret = vfs_setxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache,
211 buf, len, 0);
212 if (ret < 0) {
213 trace_cachefiles_vfs_error(NULL, d_inode(dentry), ret,
214 cachefiles_trace_setxattr_error);
215 trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino,
216 cachefiles_coherency_vol_set_fail);
217 if (ret != -ENOMEM)
218 cachefiles_io_error(
219 volume->cache, "Failed to set xattr with error %d", ret);
220 } else {
221 trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino,
222 cachefiles_coherency_vol_set_ok);
223 }
224
225 kfree(buf);
226 _leave(" = %d", ret);
227 return ret == 0;
228}
229
230/*
231 * Check the consistency between the backing cache and the volume cookie.
232 */
233int cachefiles_check_volume_xattr(struct cachefiles_volume *volume)
234{
235 struct cachefiles_vol_xattr *buf;
236 struct dentry *dentry = volume->dentry;
237 unsigned int len = volume->vcookie->coherency_len;
238 const void *p = volume->vcookie->coherency;
239 enum cachefiles_coherency_trace why;
240 ssize_t xlen;
241 int ret = -ESTALE;
242
243 _enter("");
244
245 len += sizeof(*buf);
246 buf = kmalloc(len, GFP_KERNEL);
247 if (!buf)
248 return -ENOMEM;
249
250 xlen = cachefiles_inject_read_error();
251 if (xlen == 0)
252 xlen = vfs_getxattr(&nop_mnt_idmap, dentry, cachefiles_xattr_cache, buf, len);
253 if (xlen != len) {
254 if (xlen < 0) {
255 trace_cachefiles_vfs_error(NULL, d_inode(dentry), xlen,
256 cachefiles_trace_getxattr_error);
257 if (xlen == -EIO)
258 cachefiles_io_error(
259 volume->cache,
260 "Failed to read xattr with error %zd", xlen);
261 }
262 why = cachefiles_coherency_vol_check_xattr;
263 } else if (buf->reserved != cpu_to_be32(0)) {
264 why = cachefiles_coherency_vol_check_resv;
265 } else if (memcmp(buf->data, p, len - sizeof(*buf)) != 0) {
266 why = cachefiles_coherency_vol_check_cmp;
267 } else {
268 why = cachefiles_coherency_vol_check_ok;
269 ret = 0;
270 }
271
272 trace_cachefiles_vol_coherency(volume, d_inode(dentry)->i_ino, why);
273 kfree(buf);
274 _leave(" = %d", ret);
275 return ret;
276}
1/* CacheFiles extended attribute management
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11
12#include <linux/module.h>
13#include <linux/sched.h>
14#include <linux/file.h>
15#include <linux/fs.h>
16#include <linux/fsnotify.h>
17#include <linux/quotaops.h>
18#include <linux/xattr.h>
19#include <linux/slab.h>
20#include "internal.h"
21
22static const char cachefiles_xattr_cache[] =
23 XATTR_USER_PREFIX "CacheFiles.cache";
24
25/*
26 * check the type label on an object
27 * - done using xattrs
28 */
29int cachefiles_check_object_type(struct cachefiles_object *object)
30{
31 struct dentry *dentry = object->dentry;
32 char type[3], xtype[3];
33 int ret;
34
35 ASSERT(dentry);
36 ASSERT(dentry->d_inode);
37
38 if (!object->fscache.cookie)
39 strcpy(type, "C3");
40 else
41 snprintf(type, 3, "%02x", object->fscache.cookie->def->type);
42
43 _enter("%p{%s}", object, type);
44
45 /* attempt to install a type label directly */
46 ret = vfs_setxattr(dentry, cachefiles_xattr_cache, type, 2,
47 XATTR_CREATE);
48 if (ret == 0) {
49 _debug("SET"); /* we succeeded */
50 goto error;
51 }
52
53 if (ret != -EEXIST) {
54 kerror("Can't set xattr on %*.*s [%lu] (err %d)",
55 dentry->d_name.len, dentry->d_name.len,
56 dentry->d_name.name, dentry->d_inode->i_ino,
57 -ret);
58 goto error;
59 }
60
61 /* read the current type label */
62 ret = vfs_getxattr(dentry, cachefiles_xattr_cache, xtype, 3);
63 if (ret < 0) {
64 if (ret == -ERANGE)
65 goto bad_type_length;
66
67 kerror("Can't read xattr on %*.*s [%lu] (err %d)",
68 dentry->d_name.len, dentry->d_name.len,
69 dentry->d_name.name, dentry->d_inode->i_ino,
70 -ret);
71 goto error;
72 }
73
74 /* check the type is what we're expecting */
75 if (ret != 2)
76 goto bad_type_length;
77
78 if (xtype[0] != type[0] || xtype[1] != type[1])
79 goto bad_type;
80
81 ret = 0;
82
83error:
84 _leave(" = %d", ret);
85 return ret;
86
87bad_type_length:
88 kerror("Cache object %lu type xattr length incorrect",
89 dentry->d_inode->i_ino);
90 ret = -EIO;
91 goto error;
92
93bad_type:
94 xtype[2] = 0;
95 kerror("Cache object %*.*s [%lu] type %s not %s",
96 dentry->d_name.len, dentry->d_name.len,
97 dentry->d_name.name, dentry->d_inode->i_ino,
98 xtype, type);
99 ret = -EIO;
100 goto error;
101}
102
103/*
104 * set the state xattr on a cache file
105 */
106int cachefiles_set_object_xattr(struct cachefiles_object *object,
107 struct cachefiles_xattr *auxdata)
108{
109 struct dentry *dentry = object->dentry;
110 int ret;
111
112 ASSERT(object->fscache.cookie);
113 ASSERT(dentry);
114
115 _enter("%p,#%d", object, auxdata->len);
116
117 /* attempt to install the cache metadata directly */
118 _debug("SET %s #%u", object->fscache.cookie->def->name, auxdata->len);
119
120 ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
121 &auxdata->type, auxdata->len,
122 XATTR_CREATE);
123 if (ret < 0 && ret != -ENOMEM)
124 cachefiles_io_error_obj(
125 object,
126 "Failed to set xattr with error %d", ret);
127
128 _leave(" = %d", ret);
129 return ret;
130}
131
132/*
133 * update the state xattr on a cache file
134 */
135int cachefiles_update_object_xattr(struct cachefiles_object *object,
136 struct cachefiles_xattr *auxdata)
137{
138 struct dentry *dentry = object->dentry;
139 int ret;
140
141 ASSERT(object->fscache.cookie);
142 ASSERT(dentry);
143
144 _enter("%p,#%d", object, auxdata->len);
145
146 /* attempt to install the cache metadata directly */
147 _debug("SET %s #%u", object->fscache.cookie->def->name, auxdata->len);
148
149 ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
150 &auxdata->type, auxdata->len,
151 XATTR_REPLACE);
152 if (ret < 0 && ret != -ENOMEM)
153 cachefiles_io_error_obj(
154 object,
155 "Failed to update xattr with error %d", ret);
156
157 _leave(" = %d", ret);
158 return ret;
159}
160
161/*
162 * check the state xattr on a cache file
163 * - return -ESTALE if the object should be deleted
164 */
165int cachefiles_check_object_xattr(struct cachefiles_object *object,
166 struct cachefiles_xattr *auxdata)
167{
168 struct cachefiles_xattr *auxbuf;
169 struct dentry *dentry = object->dentry;
170 int ret;
171
172 _enter("%p,#%d", object, auxdata->len);
173
174 ASSERT(dentry);
175 ASSERT(dentry->d_inode);
176
177 auxbuf = kmalloc(sizeof(struct cachefiles_xattr) + 512, GFP_KERNEL);
178 if (!auxbuf) {
179 _leave(" = -ENOMEM");
180 return -ENOMEM;
181 }
182
183 /* read the current type label */
184 ret = vfs_getxattr(dentry, cachefiles_xattr_cache,
185 &auxbuf->type, 512 + 1);
186 if (ret < 0) {
187 if (ret == -ENODATA)
188 goto stale; /* no attribute - power went off
189 * mid-cull? */
190
191 if (ret == -ERANGE)
192 goto bad_type_length;
193
194 cachefiles_io_error_obj(object,
195 "Can't read xattr on %lu (err %d)",
196 dentry->d_inode->i_ino, -ret);
197 goto error;
198 }
199
200 /* check the on-disk object */
201 if (ret < 1)
202 goto bad_type_length;
203
204 if (auxbuf->type != auxdata->type)
205 goto stale;
206
207 auxbuf->len = ret;
208
209 /* consult the netfs */
210 if (object->fscache.cookie->def->check_aux) {
211 enum fscache_checkaux result;
212 unsigned int dlen;
213
214 dlen = auxbuf->len - 1;
215
216 _debug("checkaux %s #%u",
217 object->fscache.cookie->def->name, dlen);
218
219 result = fscache_check_aux(&object->fscache,
220 &auxbuf->data, dlen);
221
222 switch (result) {
223 /* entry okay as is */
224 case FSCACHE_CHECKAUX_OKAY:
225 goto okay;
226
227 /* entry requires update */
228 case FSCACHE_CHECKAUX_NEEDS_UPDATE:
229 break;
230
231 /* entry requires deletion */
232 case FSCACHE_CHECKAUX_OBSOLETE:
233 goto stale;
234
235 default:
236 BUG();
237 }
238
239 /* update the current label */
240 ret = vfs_setxattr(dentry, cachefiles_xattr_cache,
241 &auxdata->type, auxdata->len,
242 XATTR_REPLACE);
243 if (ret < 0) {
244 cachefiles_io_error_obj(object,
245 "Can't update xattr on %lu"
246 " (error %d)",
247 dentry->d_inode->i_ino, -ret);
248 goto error;
249 }
250 }
251
252okay:
253 ret = 0;
254
255error:
256 kfree(auxbuf);
257 _leave(" = %d", ret);
258 return ret;
259
260bad_type_length:
261 kerror("Cache object %lu xattr length incorrect",
262 dentry->d_inode->i_ino);
263 ret = -EIO;
264 goto error;
265
266stale:
267 ret = -ESTALE;
268 goto error;
269}
270
271/*
272 * remove the object's xattr to mark it stale
273 */
274int cachefiles_remove_object_xattr(struct cachefiles_cache *cache,
275 struct dentry *dentry)
276{
277 int ret;
278
279 ret = vfs_removexattr(dentry, cachefiles_xattr_cache);
280 if (ret < 0) {
281 if (ret == -ENOENT || ret == -ENODATA)
282 ret = 0;
283 else if (ret != -ENOMEM)
284 cachefiles_io_error(cache,
285 "Can't remove xattr from %lu"
286 " (error %d)",
287 dentry->d_inode->i_ino, -ret);
288 }
289
290 _leave(" = %d", ret);
291 return ret;
292}