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b4d0d230 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
9ae326a6 DH |
2 | /* Bind and unbind a cache from the filesystem backing it |
3 | * | |
4 | * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. | |
5 | * Written by David Howells (dhowells@redhat.com) | |
9ae326a6 DH |
6 | */ |
7 | ||
8 | #include <linux/module.h> | |
9 | #include <linux/init.h> | |
10 | #include <linux/sched.h> | |
11 | #include <linux/completion.h> | |
12 | #include <linux/slab.h> | |
13 | #include <linux/fs.h> | |
14 | #include <linux/file.h> | |
15 | #include <linux/namei.h> | |
16 | #include <linux/mount.h> | |
17 | #include <linux/statfs.h> | |
18 | #include <linux/ctype.h> | |
5d6c3191 | 19 | #include <linux/xattr.h> |
9ae326a6 DH |
20 | #include "internal.h" |
21 | ||
22 | static int cachefiles_daemon_add_cache(struct cachefiles_cache *caches); | |
23 | ||
24 | /* | |
25 | * bind a directory as a cache | |
26 | */ | |
27 | int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args) | |
28 | { | |
29 | _enter("{%u,%u,%u,%u,%u,%u},%s", | |
30 | cache->frun_percent, | |
31 | cache->fcull_percent, | |
32 | cache->fstop_percent, | |
33 | cache->brun_percent, | |
34 | cache->bcull_percent, | |
35 | cache->bstop_percent, | |
36 | args); | |
37 | ||
38 | /* start by checking things over */ | |
39 | ASSERT(cache->fstop_percent >= 0 && | |
40 | cache->fstop_percent < cache->fcull_percent && | |
41 | cache->fcull_percent < cache->frun_percent && | |
42 | cache->frun_percent < 100); | |
43 | ||
44 | ASSERT(cache->bstop_percent >= 0 && | |
45 | cache->bstop_percent < cache->bcull_percent && | |
46 | cache->bcull_percent < cache->brun_percent && | |
47 | cache->brun_percent < 100); | |
48 | ||
49 | if (*args) { | |
6ff66ac7 | 50 | pr_err("'bind' command doesn't take an argument\n"); |
9ae326a6 DH |
51 | return -EINVAL; |
52 | } | |
53 | ||
54 | if (!cache->rootdirname) { | |
6ff66ac7 | 55 | pr_err("No cache directory specified\n"); |
9ae326a6 DH |
56 | return -EINVAL; |
57 | } | |
58 | ||
59 | /* don't permit already bound caches to be re-bound */ | |
60 | if (test_bit(CACHEFILES_READY, &cache->flags)) { | |
6ff66ac7 | 61 | pr_err("Cache already bound\n"); |
9ae326a6 DH |
62 | return -EBUSY; |
63 | } | |
64 | ||
65 | /* make sure we have copies of the tag and dirname strings */ | |
66 | if (!cache->tag) { | |
67 | /* the tag string is released by the fops->release() | |
68 | * function, so we don't release it on error here */ | |
69 | cache->tag = kstrdup("CacheFiles", GFP_KERNEL); | |
70 | if (!cache->tag) | |
71 | return -ENOMEM; | |
72 | } | |
73 | ||
74 | /* add the cache */ | |
75 | return cachefiles_daemon_add_cache(cache); | |
76 | } | |
77 | ||
78 | /* | |
79 | * add a cache | |
80 | */ | |
81 | static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache) | |
82 | { | |
83 | struct cachefiles_object *fsdef; | |
b0446be4 | 84 | struct path path; |
9ae326a6 DH |
85 | struct kstatfs stats; |
86 | struct dentry *graveyard, *cachedir, *root; | |
87 | const struct cred *saved_cred; | |
88 | int ret; | |
89 | ||
90 | _enter(""); | |
91 | ||
92 | /* we want to work under the module's security ID */ | |
93 | ret = cachefiles_get_security_ID(cache); | |
94 | if (ret < 0) | |
95 | return ret; | |
96 | ||
97 | cachefiles_begin_secure(cache, &saved_cred); | |
98 | ||
99 | /* allocate the root index object */ | |
100 | ret = -ENOMEM; | |
101 | ||
102 | fsdef = kmem_cache_alloc(cachefiles_object_jar, GFP_KERNEL); | |
103 | if (!fsdef) | |
104 | goto error_root_object; | |
105 | ||
106 | ASSERTCMP(fsdef->backer, ==, NULL); | |
107 | ||
108 | atomic_set(&fsdef->usage, 1); | |
109 | fsdef->type = FSCACHE_COOKIE_TYPE_INDEX; | |
110 | ||
111 | _debug("- fsdef %p", fsdef); | |
112 | ||
113 | /* look up the directory at the root of the cache */ | |
b0446be4 | 114 | ret = kern_path(cache->rootdirname, LOOKUP_DIRECTORY, &path); |
9ae326a6 DH |
115 | if (ret < 0) |
116 | goto error_open_root; | |
117 | ||
b0446be4 AV |
118 | cache->mnt = path.mnt; |
119 | root = path.dentry; | |
9ae326a6 | 120 | |
bf1c82a5 CB |
121 | ret = -EINVAL; |
122 | if (mnt_user_ns(path.mnt) != &init_user_ns) { | |
123 | pr_warn("File cache on idmapped mounts not supported"); | |
124 | goto error_unsupported; | |
125 | } | |
126 | ||
9ae326a6 DH |
127 | /* check parameters */ |
128 | ret = -EOPNOTSUPP; | |
466b77bc DH |
129 | if (d_is_negative(root) || |
130 | !d_backing_inode(root)->i_op->lookup || | |
131 | !d_backing_inode(root)->i_op->mkdir || | |
5d6c3191 | 132 | !(d_backing_inode(root)->i_opflags & IOP_XATTR) || |
9ae326a6 DH |
133 | !root->d_sb->s_op->statfs || |
134 | !root->d_sb->s_op->sync_fs) | |
135 | goto error_unsupported; | |
136 | ||
137 | ret = -EROFS; | |
bc98a42c | 138 | if (sb_rdonly(root->d_sb)) |
9ae326a6 DH |
139 | goto error_unsupported; |
140 | ||
141 | /* determine the security of the on-disk cache as this governs | |
142 | * security ID of files we create */ | |
143 | ret = cachefiles_determine_cache_security(cache, root, &saved_cred); | |
144 | if (ret < 0) | |
145 | goto error_unsupported; | |
146 | ||
147 | /* get the cache size and blocksize */ | |
ebabe9a9 | 148 | ret = vfs_statfs(&path, &stats); |
9ae326a6 DH |
149 | if (ret < 0) |
150 | goto error_unsupported; | |
151 | ||
152 | ret = -ERANGE; | |
153 | if (stats.f_bsize <= 0) | |
154 | goto error_unsupported; | |
155 | ||
156 | ret = -EOPNOTSUPP; | |
157 | if (stats.f_bsize > PAGE_SIZE) | |
158 | goto error_unsupported; | |
159 | ||
160 | cache->bsize = stats.f_bsize; | |
161 | cache->bshift = 0; | |
162 | if (stats.f_bsize < PAGE_SIZE) | |
163 | cache->bshift = PAGE_SHIFT - ilog2(stats.f_bsize); | |
164 | ||
165 | _debug("blksize %u (shift %u)", | |
166 | cache->bsize, cache->bshift); | |
167 | ||
168 | _debug("size %llu, avail %llu", | |
169 | (unsigned long long) stats.f_blocks, | |
170 | (unsigned long long) stats.f_bavail); | |
171 | ||
172 | /* set up caching limits */ | |
173 | do_div(stats.f_files, 100); | |
174 | cache->fstop = stats.f_files * cache->fstop_percent; | |
175 | cache->fcull = stats.f_files * cache->fcull_percent; | |
176 | cache->frun = stats.f_files * cache->frun_percent; | |
177 | ||
178 | _debug("limits {%llu,%llu,%llu} files", | |
179 | (unsigned long long) cache->frun, | |
180 | (unsigned long long) cache->fcull, | |
181 | (unsigned long long) cache->fstop); | |
182 | ||
183 | stats.f_blocks >>= cache->bshift; | |
184 | do_div(stats.f_blocks, 100); | |
185 | cache->bstop = stats.f_blocks * cache->bstop_percent; | |
186 | cache->bcull = stats.f_blocks * cache->bcull_percent; | |
187 | cache->brun = stats.f_blocks * cache->brun_percent; | |
188 | ||
189 | _debug("limits {%llu,%llu,%llu} blocks", | |
190 | (unsigned long long) cache->brun, | |
191 | (unsigned long long) cache->bcull, | |
192 | (unsigned long long) cache->bstop); | |
193 | ||
194 | /* get the cache directory and check its type */ | |
195 | cachedir = cachefiles_get_directory(cache, root, "cache"); | |
196 | if (IS_ERR(cachedir)) { | |
197 | ret = PTR_ERR(cachedir); | |
198 | goto error_unsupported; | |
199 | } | |
200 | ||
201 | fsdef->dentry = cachedir; | |
202 | fsdef->fscache.cookie = NULL; | |
203 | ||
204 | ret = cachefiles_check_object_type(fsdef); | |
205 | if (ret < 0) | |
206 | goto error_unsupported; | |
207 | ||
208 | /* get the graveyard directory */ | |
209 | graveyard = cachefiles_get_directory(cache, root, "graveyard"); | |
210 | if (IS_ERR(graveyard)) { | |
211 | ret = PTR_ERR(graveyard); | |
212 | goto error_unsupported; | |
213 | } | |
214 | ||
215 | cache->graveyard = graveyard; | |
216 | ||
217 | /* publish the cache */ | |
218 | fscache_init_cache(&cache->cache, | |
219 | &cachefiles_cache_ops, | |
220 | "%s", | |
221 | fsdef->dentry->d_sb->s_id); | |
222 | ||
f29507ce KKM |
223 | fscache_object_init(&fsdef->fscache, &fscache_fsdef_index, |
224 | &cache->cache); | |
9ae326a6 DH |
225 | |
226 | ret = fscache_add_cache(&cache->cache, &fsdef->fscache, cache->tag); | |
227 | if (ret < 0) | |
228 | goto error_add_cache; | |
229 | ||
230 | /* done */ | |
231 | set_bit(CACHEFILES_READY, &cache->flags); | |
232 | dput(root); | |
233 | ||
0227d6ab | 234 | pr_info("File cache on %s registered\n", cache->cache.identifier); |
9ae326a6 DH |
235 | |
236 | /* check how much space the cache has */ | |
237 | cachefiles_has_space(cache, 0, 0); | |
238 | cachefiles_end_secure(cache, saved_cred); | |
239 | return 0; | |
240 | ||
241 | error_add_cache: | |
242 | dput(cache->graveyard); | |
243 | cache->graveyard = NULL; | |
244 | error_unsupported: | |
245 | mntput(cache->mnt); | |
246 | cache->mnt = NULL; | |
247 | dput(fsdef->dentry); | |
248 | fsdef->dentry = NULL; | |
249 | dput(root); | |
250 | error_open_root: | |
251 | kmem_cache_free(cachefiles_object_jar, fsdef); | |
252 | error_root_object: | |
253 | cachefiles_end_secure(cache, saved_cred); | |
6ff66ac7 | 254 | pr_err("Failed to register: %d\n", ret); |
9ae326a6 DH |
255 | return ret; |
256 | } | |
257 | ||
258 | /* | |
259 | * unbind a cache on fd release | |
260 | */ | |
261 | void cachefiles_daemon_unbind(struct cachefiles_cache *cache) | |
262 | { | |
263 | _enter(""); | |
264 | ||
265 | if (test_bit(CACHEFILES_READY, &cache->flags)) { | |
0227d6ab | 266 | pr_info("File cache on %s unregistering\n", |
4e1eb883 | 267 | cache->cache.identifier); |
9ae326a6 DH |
268 | |
269 | fscache_withdraw_cache(&cache->cache); | |
270 | } | |
271 | ||
272 | dput(cache->graveyard); | |
273 | mntput(cache->mnt); | |
274 | ||
275 | kfree(cache->rootdirname); | |
276 | kfree(cache->secctx); | |
277 | kfree(cache->tag); | |
278 | ||
279 | _leave(""); | |
280 | } |