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72b95785 DH |
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 | ||
20 | struct 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 | ||
28 | static const char cachefiles_xattr_cache[] = | |
29 | XATTR_USER_PREFIX "CacheFiles.cache"; | |
30 | ||
413a4a6b DH |
31 | struct cachefiles_vol_xattr { |
32 | __be32 reserved; /* Reserved, should be 0 */ | |
33 | __u8 data[]; /* netfs volume coherency data */ | |
34 | } __packed; | |
35 | ||
72b95785 DH |
36 | /* |
37 | * set the state xattr on a cache file | |
38 | */ | |
39 | int 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(&init_user_ns, 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 | */ | |
94 | int 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(&init_user_ns, 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 | */ | |
145 | int 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(&init_user_ns, 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 | */ | |
173 | void 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 | } | |
32e15003 DH |
187 | |
188 | /* | |
189 | * Set the state xattr on a volume directory. | |
190 | */ | |
191 | bool cachefiles_set_volume_xattr(struct cachefiles_volume *volume) | |
192 | { | |
413a4a6b | 193 | struct cachefiles_vol_xattr *buf; |
32e15003 DH |
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 | ||
413a4a6b DH |
201 | len += sizeof(*buf); |
202 | buf = kmalloc(len, GFP_KERNEL); | |
203 | if (!buf) | |
204 | return false; | |
205 | buf->reserved = cpu_to_be32(0); | |
7b2f6c30 | 206 | memcpy(buf->data, p, volume->vcookie->coherency_len); |
413a4a6b | 207 | |
32e15003 DH |
208 | ret = cachefiles_inject_write_error(); |
209 | if (ret == 0) | |
210 | ret = vfs_setxattr(&init_user_ns, dentry, cachefiles_xattr_cache, | |
413a4a6b | 211 | buf, len, 0); |
32e15003 DH |
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 | ||
413a4a6b | 225 | kfree(buf); |
32e15003 DH |
226 | _leave(" = %d", ret); |
227 | return ret == 0; | |
228 | } | |
229 | ||
230 | /* | |
231 | * Check the consistency between the backing cache and the volume cookie. | |
232 | */ | |
233 | int cachefiles_check_volume_xattr(struct cachefiles_volume *volume) | |
234 | { | |
413a4a6b | 235 | struct cachefiles_vol_xattr *buf; |
32e15003 DH |
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 | ||
413a4a6b | 245 | len += sizeof(*buf); |
32e15003 DH |
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(&init_user_ns, 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; | |
413a4a6b DH |
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) { | |
32e15003 DH |
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 | } |