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