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 | |
31 | struct 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 | */ |
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(size: 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(obj: object, backer: file_inode(f: file), error: ret, |
72 | where: cachefiles_trace_setxattr_error); |
73 | trace_cachefiles_coherency(obj: object, ino: file_inode(f: file)->i_ino, |
74 | content: buf->content, |
75 | why: 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(obj: object, ino: file_inode(f: file)->i_ino, |
82 | content: buf->content, |
83 | why: cachefiles_coherency_set_ok); |
84 | } |
85 | |
86 | kfree(objp: 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(cookie: 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(size: 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(obj: object, backer: file_inode(f: file), error: xlen, |
115 | where: 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(p: buf->data, q: p, size: 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(obj: object, ino: file_inode(f: file)->i_ino, |
137 | content: buf->content, why); |
138 | kfree(objp: 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(&nop_mnt_idmap, dentry, cachefiles_xattr_cache); |
154 | if (ret < 0) { |
155 | trace_cachefiles_vfs_error(obj: object, backer: d_inode(dentry), error: ret, |
156 | where: 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: &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 | */ |
191 | bool 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(size: 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, backer: d_inode(dentry), error: ret, |
214 | where: cachefiles_trace_setxattr_error); |
215 | trace_cachefiles_vol_coherency(volume, ino: d_inode(dentry)->i_ino, |
216 | why: 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, ino: d_inode(dentry)->i_ino, |
222 | why: cachefiles_coherency_vol_set_ok); |
223 | } |
224 | |
225 | kfree(objp: 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 | */ |
233 | int 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(size: 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, backer: d_inode(dentry), error: xlen, |
256 | where: 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(p: buf->data, q: p, size: 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, ino: d_inode(dentry)->i_ino, why); |
273 | kfree(objp: buf); |
274 | _leave(" = %d" , ret); |
275 | return ret; |
276 | } |
277 | |