1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * include/linux/sunrpc/cache.h
4 *
5 * Generic code for various authentication-related caches
6 * used by sunrpc clients and servers.
7 *
8 * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
9 */
10
11 #ifndef _LINUX_SUNRPC_CACHE_H_
12 #define _LINUX_SUNRPC_CACHE_H_
13
14 #include <linux/kref.h>
15 #include <linux/slab.h>
16 #include <linux/atomic.h>
17 #include <linux/kstrtox.h>
18 #include <linux/proc_fs.h>
19
20 /*
21 * Each cache requires:
22 * - A 'struct cache_detail' which contains information specific to the cache
23 * for common code to use.
24 * - An item structure that must contain a "struct cache_head"
25 * - A lookup function defined using DefineCacheLookup
26 * - A 'put' function that can release a cache item. It will only
27 * be called after cache_put has succeed, so there are guarantee
28 * to be no references.
29 * - A function to calculate a hash of an item's key.
30 *
31 * as well as assorted code fragments (e.g. compare keys) and numbers
32 * (e.g. hash size, goal_age, etc).
33 *
34 * Each cache must be registered so that it can be cleaned regularly.
35 * When the cache is unregistered, it is flushed completely.
36 *
37 * Entries have a ref count and a 'hashed' flag which counts the existence
38 * in the hash table.
39 * We only expire entries when refcount is zero.
40 * Existence in the cache is counted the refcount.
41 */
42
43 /* Every cache item has a common header that is used
44 * for expiring and refreshing entries.
45 *
46 */
47 struct cache_head {
48 struct hlist_node cache_list;
49 time64_t expiry_time; /* After time expiry_time, don't use
50 * the data */
51 time64_t last_refresh; /* If CACHE_PENDING, this is when upcall was
52 * sent, else this is when update was
53 * received, though it is alway set to
54 * be *after* ->flush_time.
55 */
56 struct kref ref;
57 unsigned long flags;
58 };
59 #define CACHE_VALID 0 /* Entry contains valid data */
60 #define CACHE_NEGATIVE 1 /* Negative entry - there is no match for the key */
61 #define CACHE_PENDING 2 /* An upcall has been sent but no reply received yet*/
62 #define CACHE_CLEANED 3 /* Entry has been cleaned from cache */
63
64 #define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */
65
66 struct cache_detail {
67 struct module * owner;
68 int hash_size;
69 struct hlist_head * hash_table;
70 spinlock_t hash_lock;
71
72 char *name;
73 void (*cache_put)(struct kref *);
74
75 int (*cache_upcall)(struct cache_detail *,
76 struct cache_head *);
77
78 void (*cache_request)(struct cache_detail *cd,
79 struct cache_head *ch,
80 char **bpp, int *blen);
81
82 int (*cache_parse)(struct cache_detail *,
83 char *buf, int len);
84
85 int (*cache_show)(struct seq_file *m,
86 struct cache_detail *cd,
87 struct cache_head *h);
88 void (*warn_no_listener)(struct cache_detail *cd,
89 int has_died);
90
91 struct cache_head * (*alloc)(void);
92 void (*flush)(void);
93 int (*match)(struct cache_head *orig, struct cache_head *new);
94 void (*init)(struct cache_head *orig, struct cache_head *new);
95 void (*update)(struct cache_head *orig, struct cache_head *new);
96
97 /* fields below this comment are for internal use
98 * and should not be touched by cache owners
99 */
100 time64_t flush_time; /* flush all cache items with
101 * last_refresh at or earlier
102 * than this. last_refresh
103 * is never set at or earlier
104 * than this.
105 */
106 struct list_head others;
107 time64_t nextcheck;
108 int entries;
109
110 /* fields for communication over channel */
111 struct list_head queue;
112
113 atomic_t writers; /* how many time is /channel open */
114 time64_t last_close; /* if no writers, when did last close */
115 time64_t last_warn; /* when we last warned about no writers */
116
117 union {
118 struct proc_dir_entry *procfs;
119 struct dentry *pipefs;
120 };
121 struct net *net;
122 };
123
124
125 /* this must be embedded in any request structure that
126 * identifies an object that will want a callback on
127 * a cache fill
128 */
129 struct cache_req {
130 struct cache_deferred_req *(*defer)(struct cache_req *req);
131 int thread_wait; /* How long (jiffies) we can block the
132 * current thread to wait for updates.
133 */
134 };
135 /* this must be embedded in a deferred_request that is being
136 * delayed awaiting cache-fill
137 */
138 struct cache_deferred_req {
139 struct hlist_node hash; /* on hash chain */
140 struct list_head recent; /* on fifo */
141 struct cache_head *item; /* cache item we wait on */
142 void *owner; /* we might need to discard all defered requests
143 * owned by someone */
144 void (*revisit)(struct cache_deferred_req *req,
145 int too_many);
146 };
147
148 /*
149 * timestamps kept in the cache are expressed in seconds
150 * since boot. This is the best for measuring differences in
151 * real time.
152 * This reimplemnts ktime_get_boottime_seconds() in a slightly
153 * faster but less accurate way. When we end up converting
154 * back to wallclock (CLOCK_REALTIME), that error often
155 * cancels out during the reverse operation.
156 */
seconds_since_boot(void)157 static inline time64_t seconds_since_boot(void)
158 {
159 struct timespec64 boot;
160 getboottime64(&boot);
161 return ktime_get_real_seconds() - boot.tv_sec;
162 }
163
convert_to_wallclock(time64_t sinceboot)164 static inline time64_t convert_to_wallclock(time64_t sinceboot)
165 {
166 struct timespec64 boot;
167 getboottime64(&boot);
168 return boot.tv_sec + sinceboot;
169 }
170
171 extern const struct file_operations cache_file_operations_pipefs;
172 extern const struct file_operations content_file_operations_pipefs;
173 extern const struct file_operations cache_flush_operations_pipefs;
174
175 extern struct cache_head *
176 sunrpc_cache_lookup_rcu(struct cache_detail *detail,
177 struct cache_head *key, int hash);
178 extern struct cache_head *
179 sunrpc_cache_update(struct cache_detail *detail,
180 struct cache_head *new, struct cache_head *old, int hash);
181
182 extern int
183 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
184 extern int
185 sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
186 struct cache_head *h);
187
188
189 extern void cache_clean_deferred(void *owner);
190
cache_get(struct cache_head * h)191 static inline struct cache_head *cache_get(struct cache_head *h)
192 {
193 kref_get(&h->ref);
194 return h;
195 }
196
cache_get_rcu(struct cache_head * h)197 static inline struct cache_head *cache_get_rcu(struct cache_head *h)
198 {
199 if (kref_get_unless_zero(&h->ref))
200 return h;
201 return NULL;
202 }
203
cache_put(struct cache_head * h,struct cache_detail * cd)204 static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
205 {
206 if (kref_read(&h->ref) <= 2 &&
207 h->expiry_time < cd->nextcheck)
208 cd->nextcheck = h->expiry_time;
209 kref_put(&h->ref, cd->cache_put);
210 }
211
cache_is_expired(struct cache_detail * detail,struct cache_head * h)212 static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
213 {
214 if (h->expiry_time < seconds_since_boot())
215 return true;
216 if (!test_bit(CACHE_VALID, &h->flags))
217 return false;
218 return detail->flush_time >= h->last_refresh;
219 }
220
221 extern int cache_check(struct cache_detail *detail,
222 struct cache_head *h, struct cache_req *rqstp);
223 extern void cache_flush(void);
224 extern void cache_purge(struct cache_detail *detail);
225 #define NEVER (0x7FFFFFFF)
226 extern void __init cache_initialize(void);
227 extern int cache_register_net(struct cache_detail *cd, struct net *net);
228 extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
229
230 extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net);
231 extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
232
233 extern void sunrpc_init_cache_detail(struct cache_detail *cd);
234 extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
235 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
236 umode_t, struct cache_detail *);
237 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
238 extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);
239
240 /* Must store cache_detail in seq_file->private if using next three functions */
241 extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos);
242 extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos);
243 extern void cache_seq_stop_rcu(struct seq_file *file, void *p);
244
245 extern void qword_add(char **bpp, int *lp, char *str);
246 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
247 extern int qword_get(char **bpp, char *dest, int bufsize);
248
get_int(char ** bpp,int * anint)249 static inline int get_int(char **bpp, int *anint)
250 {
251 char buf[50];
252 char *ep;
253 int rv;
254 int len = qword_get(bpp, buf, sizeof(buf));
255
256 if (len < 0)
257 return -EINVAL;
258 if (len == 0)
259 return -ENOENT;
260
261 rv = simple_strtol(buf, &ep, 0);
262 if (*ep)
263 return -EINVAL;
264
265 *anint = rv;
266 return 0;
267 }
268
get_uint(char ** bpp,unsigned int * anint)269 static inline int get_uint(char **bpp, unsigned int *anint)
270 {
271 char buf[50];
272 int len = qword_get(bpp, buf, sizeof(buf));
273
274 if (len < 0)
275 return -EINVAL;
276 if (len == 0)
277 return -ENOENT;
278
279 if (kstrtouint(buf, 0, anint))
280 return -EINVAL;
281
282 return 0;
283 }
284
get_time(char ** bpp,time64_t * time)285 static inline int get_time(char **bpp, time64_t *time)
286 {
287 char buf[50];
288 long long ll;
289 int len = qword_get(bpp, buf, sizeof(buf));
290
291 if (len < 0)
292 return -EINVAL;
293 if (len == 0)
294 return -ENOENT;
295
296 if (kstrtoll(buf, 0, &ll))
297 return -EINVAL;
298
299 *time = ll;
300 return 0;
301 }
302
get_expiry(char ** bpp)303 static inline time64_t get_expiry(char **bpp)
304 {
305 time64_t rv;
306 struct timespec64 boot;
307
308 if (get_time(bpp, &rv))
309 return 0;
310 if (rv < 0)
311 return 0;
312 getboottime64(&boot);
313 return rv - boot.tv_sec;
314 }
315
316 #endif /* _LINUX_SUNRPC_CACHE_H_ */
317