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
60 /* cache_head.flags */
61 enum {
62 CACHE_VALID, /* Entry contains valid data */
63 CACHE_NEGATIVE, /* Negative entry - there is no match for the key */
64 CACHE_PENDING, /* An upcall has been sent but no reply received yet*/
65 CACHE_CLEANED, /* Entry has been cleaned from cache */
66 };
67
68 #define CACHE_NEW_EXPIRY 120 /* keep new things pending confirmation for 120 seconds */
69
70 struct cache_detail {
71 struct module * owner;
72 int hash_size;
73 struct hlist_head * hash_table;
74 spinlock_t hash_lock;
75
76 char *name;
77 void (*cache_put)(struct kref *);
78
79 int (*cache_upcall)(struct cache_detail *,
80 struct cache_head *);
81
82 void (*cache_request)(struct cache_detail *cd,
83 struct cache_head *ch,
84 char **bpp, int *blen);
85
86 int (*cache_parse)(struct cache_detail *,
87 char *buf, int len);
88
89 int (*cache_show)(struct seq_file *m,
90 struct cache_detail *cd,
91 struct cache_head *h);
92 void (*warn_no_listener)(struct cache_detail *cd,
93 int has_died);
94
95 struct cache_head * (*alloc)(void);
96 void (*flush)(void);
97 int (*match)(struct cache_head *orig, struct cache_head *new);
98 void (*init)(struct cache_head *orig, struct cache_head *new);
99 void (*update)(struct cache_head *orig, struct cache_head *new);
100
101 /* fields below this comment are for internal use
102 * and should not be touched by cache owners
103 */
104 time64_t flush_time; /* flush all cache items with
105 * last_refresh at or earlier
106 * than this. last_refresh
107 * is never set at or earlier
108 * than this.
109 */
110 struct list_head others;
111 time64_t nextcheck;
112 int entries;
113
114 /* fields for communication over channel */
115 struct list_head queue;
116
117 atomic_t writers; /* how many time is /channel open */
118 time64_t last_close; /* if no writers, when did last close */
119 time64_t last_warn; /* when we last warned about no writers */
120
121 union {
122 struct proc_dir_entry *procfs;
123 struct dentry *pipefs;
124 };
125 struct net *net;
126 };
127
128 /* this must be embedded in any request structure that
129 * identifies an object that will want a callback on
130 * a cache fill
131 */
132 struct cache_req {
133 struct cache_deferred_req *(*defer)(struct cache_req *req);
134 unsigned long thread_wait; /* How long (jiffies) we can block the
135 * current thread to wait for updates.
136 */
137 };
138
139 /* this must be embedded in a deferred_request that is being
140 * delayed awaiting cache-fill
141 */
142 struct cache_deferred_req {
143 struct hlist_node hash; /* on hash chain */
144 struct list_head recent; /* on fifo */
145 struct cache_head *item; /* cache item we wait on */
146 void *owner; /* we might need to discard all defered requests
147 * owned by someone */
148 void (*revisit)(struct cache_deferred_req *req,
149 int too_many);
150 };
151
152 /*
153 * timestamps kept in the cache are expressed in seconds
154 * since boot. This is the best for measuring differences in
155 * real time.
156 * This reimplemnts ktime_get_boottime_seconds() in a slightly
157 * faster but less accurate way. When we end up converting
158 * back to wallclock (CLOCK_REALTIME), that error often
159 * cancels out during the reverse operation.
160 */
seconds_since_boot(void)161 static inline time64_t seconds_since_boot(void)
162 {
163 struct timespec64 boot;
164 getboottime64(&boot);
165 return ktime_get_real_seconds() - boot.tv_sec;
166 }
167
convert_to_wallclock(time64_t sinceboot)168 static inline time64_t convert_to_wallclock(time64_t sinceboot)
169 {
170 struct timespec64 boot;
171 getboottime64(&boot);
172 return boot.tv_sec + sinceboot;
173 }
174
175 extern const struct file_operations cache_file_operations_pipefs;
176 extern const struct file_operations content_file_operations_pipefs;
177 extern const struct file_operations cache_flush_operations_pipefs;
178
179 extern struct cache_head *
180 sunrpc_cache_lookup_rcu(struct cache_detail *detail,
181 struct cache_head *key, int hash);
182 extern struct cache_head *
183 sunrpc_cache_update(struct cache_detail *detail,
184 struct cache_head *new, struct cache_head *old, int hash);
185
186 extern int
187 sunrpc_cache_pipe_upcall(struct cache_detail *detail, struct cache_head *h);
188 extern int
189 sunrpc_cache_pipe_upcall_timeout(struct cache_detail *detail,
190 struct cache_head *h);
191
192
193 extern void cache_clean_deferred(void *owner);
194
cache_get(struct cache_head * h)195 static inline struct cache_head *cache_get(struct cache_head *h)
196 {
197 kref_get(&h->ref);
198 return h;
199 }
200
cache_get_rcu(struct cache_head * h)201 static inline struct cache_head *cache_get_rcu(struct cache_head *h)
202 {
203 if (kref_get_unless_zero(&h->ref))
204 return h;
205 return NULL;
206 }
207
cache_put(struct cache_head * h,struct cache_detail * cd)208 static inline void cache_put(struct cache_head *h, struct cache_detail *cd)
209 {
210 if (kref_read(&h->ref) <= 2 &&
211 h->expiry_time < cd->nextcheck)
212 cd->nextcheck = h->expiry_time;
213 kref_put(&h->ref, cd->cache_put);
214 }
215
cache_is_expired(struct cache_detail * detail,struct cache_head * h)216 static inline bool cache_is_expired(struct cache_detail *detail, struct cache_head *h)
217 {
218 if (h->expiry_time < seconds_since_boot())
219 return true;
220 if (!test_bit(CACHE_VALID, &h->flags))
221 return false;
222 return detail->flush_time >= h->last_refresh;
223 }
224
225 extern int cache_check(struct cache_detail *detail,
226 struct cache_head *h, struct cache_req *rqstp);
227 extern void cache_flush(void);
228 extern void cache_purge(struct cache_detail *detail);
229 #define NEVER (0x7FFFFFFF)
230 extern void __init cache_initialize(void);
231 extern int cache_register_net(struct cache_detail *cd, struct net *net);
232 extern void cache_unregister_net(struct cache_detail *cd, struct net *net);
233
234 extern struct cache_detail *cache_create_net(const struct cache_detail *tmpl, struct net *net);
235 extern void cache_destroy_net(struct cache_detail *cd, struct net *net);
236
237 extern void sunrpc_init_cache_detail(struct cache_detail *cd);
238 extern void sunrpc_destroy_cache_detail(struct cache_detail *cd);
239 extern int sunrpc_cache_register_pipefs(struct dentry *parent, const char *,
240 umode_t, struct cache_detail *);
241 extern void sunrpc_cache_unregister_pipefs(struct cache_detail *);
242 extern void sunrpc_cache_unhash(struct cache_detail *, struct cache_head *);
243
244 /* Must store cache_detail in seq_file->private if using next three functions */
245 extern void *cache_seq_start_rcu(struct seq_file *file, loff_t *pos);
246 extern void *cache_seq_next_rcu(struct seq_file *file, void *p, loff_t *pos);
247 extern void cache_seq_stop_rcu(struct seq_file *file, void *p);
248
249 extern void qword_add(char **bpp, int *lp, char *str);
250 extern void qword_addhex(char **bpp, int *lp, char *buf, int blen);
251 extern int qword_get(char **bpp, char *dest, int bufsize);
252
get_int(char ** bpp,int * anint)253 static inline int get_int(char **bpp, int *anint)
254 {
255 char buf[50];
256 char *ep;
257 int rv;
258 int len = qword_get(bpp, buf, sizeof(buf));
259
260 if (len < 0)
261 return -EINVAL;
262 if (len == 0)
263 return -ENOENT;
264
265 rv = simple_strtol(buf, &ep, 0);
266 if (*ep)
267 return -EINVAL;
268
269 *anint = rv;
270 return 0;
271 }
272
get_uint(char ** bpp,unsigned int * anint)273 static inline int get_uint(char **bpp, unsigned int *anint)
274 {
275 char buf[50];
276 int len = qword_get(bpp, buf, sizeof(buf));
277
278 if (len < 0)
279 return -EINVAL;
280 if (len == 0)
281 return -ENOENT;
282
283 if (kstrtouint(buf, 0, anint))
284 return -EINVAL;
285
286 return 0;
287 }
288
get_time(char ** bpp,time64_t * time)289 static inline int get_time(char **bpp, time64_t *time)
290 {
291 char buf[50];
292 long long ll;
293 int len = qword_get(bpp, buf, sizeof(buf));
294
295 if (len < 0)
296 return -EINVAL;
297 if (len == 0)
298 return -ENOENT;
299
300 if (kstrtoll(buf, 0, &ll))
301 return -EINVAL;
302
303 *time = ll;
304 return 0;
305 }
306
get_expiry(char ** bpp,time64_t * rvp)307 static inline int get_expiry(char **bpp, time64_t *rvp)
308 {
309 int error;
310 struct timespec64 boot;
311
312 error = get_time(bpp, rvp);
313 if (error)
314 return error;
315
316 getboottime64(&boot);
317 (*rvp) -= boot.tv_sec;
318 return 0;
319 }
320
321 #endif /* _LINUX_SUNRPC_CACHE_H_ */
322