1 /* Copyright (c) 1998-2022 Free Software Foundation, Inc.
2    This file is part of the GNU C Library.
3 
4    The GNU C Library is free software; you can redistribute it and/or
5    modify it under the terms of the GNU Lesser General Public
6    License as published by the Free Software Foundation; either
7    version 2.1 of the License, or (at your option) any later version.
8 
9    The GNU C Library is distributed in the hope that it will be useful,
10    but WITHOUT ANY WARRANTY; without even the implied warranty of
11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12    Lesser General Public License for more details.
13 
14    You should have received a copy of the GNU Lesser General Public
15    License along with the GNU C Library; if not, see
16    <https://www.gnu.org/licenses/>.  */
17 
18 /* This file defines everything that client code should need to
19    know to talk to the nscd daemon.  */
20 
21 #ifndef _NSCD_CLIENT_H
22 #define _NSCD_CLIENT_H	1
23 
24 #include <stdbool.h>
25 #include <stdint.h>
26 #include <string.h>
27 #include <time.h>
28 #include <sys/types.h>
29 #include <atomic.h>
30 #include <nscd-types.h>
31 #include <sys/uio.h>
32 
33 
34 /* Version number of the daemon interface */
35 #define NSCD_VERSION 2
36 
37 /* Path of the file where the PID of the running system is stored.  */
38 #define _PATH_NSCDPID	 "/var/run/nscd/nscd.pid"
39 
40 /* Path for the Unix domain socket.  */
41 #define _PATH_NSCDSOCKET "/var/run/nscd/socket"
42 
43 /* Path for the configuration file.  */
44 #define _PATH_NSCDCONF	 "/etc/nscd.conf"
45 
46 /* Maximum allowed length for the key.  */
47 #define MAXKEYLEN 1024
48 
49 
50 /* Available services.  */
51 typedef enum
52 {
53   GETPWBYNAME,
54   GETPWBYUID,
55   GETGRBYNAME,
56   GETGRBYGID,
57   GETHOSTBYNAME,
58   GETHOSTBYNAMEv6,
59   GETHOSTBYADDR,
60   GETHOSTBYADDRv6,
61   SHUTDOWN,		/* Shut the server down.  */
62   GETSTAT,		/* Get the server statistic.  */
63   INVALIDATE,           /* Invalidate one special cache.  */
64   GETFDPW,
65   GETFDGR,
66   GETFDHST,
67   GETAI,
68   INITGROUPS,
69   GETSERVBYNAME,
70   GETSERVBYPORT,
71   GETFDSERV,
72   GETNETGRENT,
73   INNETGR,
74   GETFDNETGR,
75   LASTREQ
76 } request_type;
77 
78 
79 /* Header common to all requests */
80 typedef struct
81 {
82   int32_t version;	/* Version number of the daemon interface.  */
83   request_type type;	/* Service requested.  */
84   int32_t key_len;	/* Key length.  */
85 } request_header;
86 
87 
88 /* Structure sent in reply to password query.  Note that this struct is
89    sent also if the service is disabled or there is no record found.  */
90 typedef struct
91 {
92   int32_t version;
93   int32_t found;
94   nscd_ssize_t pw_name_len;
95   nscd_ssize_t pw_passwd_len;
96   uid_t pw_uid;
97   gid_t pw_gid;
98   nscd_ssize_t pw_gecos_len;
99   nscd_ssize_t pw_dir_len;
100   nscd_ssize_t pw_shell_len;
101 } pw_response_header;
102 
103 
104 /* Structure sent in reply to group query.  Note that this struct is
105    sent also if the service is disabled or there is no record found.  */
106 typedef struct
107 {
108   int32_t version;
109   int32_t found;
110   nscd_ssize_t gr_name_len;
111   nscd_ssize_t gr_passwd_len;
112   gid_t gr_gid;
113   nscd_ssize_t gr_mem_cnt;
114 } gr_response_header;
115 
116 
117 /* Structure sent in reply to host query.  Note that this struct is
118    sent also if the service is disabled or there is no record found.  */
119 typedef struct
120 {
121   int32_t version;
122   int32_t found;
123   nscd_ssize_t h_name_len;
124   nscd_ssize_t h_aliases_cnt;
125   int32_t h_addrtype;
126   int32_t h_length;
127   nscd_ssize_t h_addr_list_cnt;
128   int32_t error;
129 } hst_response_header;
130 
131 
132 /* Structure sent in reply to addrinfo query.  Note that this struct is
133    sent also if the service is disabled or there is no record found.  */
134 typedef struct
135 {
136   int32_t version;
137   int32_t found;
138   nscd_ssize_t naddrs;
139   nscd_ssize_t addrslen;
140   nscd_ssize_t canonlen;
141   int32_t error;
142 } ai_response_header;
143 
144 /* Structure filled in by __nscd_getai.  */
145 struct nscd_ai_result
146 {
147   int naddrs;
148   char *canon;
149   uint8_t *family;
150   char *addrs;
151 };
152 
153 /* Structure sent in reply to initgroups query.  Note that this struct is
154    sent also if the service is disabled or there is no record found.  */
155 typedef struct
156 {
157   int32_t version;
158   int32_t found;
159   nscd_ssize_t ngrps;
160 } initgr_response_header;
161 
162 
163 /* Structure sent in reply to services query.  Note that this struct is
164    sent also if the service is disabled or there is no record found.  */
165 typedef struct
166 {
167   int32_t version;
168   int32_t found;
169   nscd_ssize_t s_name_len;
170   nscd_ssize_t s_proto_len;
171   nscd_ssize_t s_aliases_cnt;
172   int32_t s_port;
173 } serv_response_header;
174 
175 
176 /* Structure send in reply to netgroup query.  Note that this struct is
177    sent also if the service is disabled or there is no record found.  */
178 typedef struct
179 {
180   int32_t version;
181   int32_t found;
182   nscd_ssize_t nresults;
183   nscd_ssize_t result_len;
184 } netgroup_response_header;
185 
186 typedef struct
187 {
188   int32_t version;
189   int32_t found;
190   int32_t result;
191 } innetgroup_response_header;
192 
193 
194 /* Type for offsets in data part of database.  */
195 typedef uint32_t ref_t;
196 /* Value for invalid/no reference.  */
197 #define ENDREF	UINT32_MAX
198 
199 /* Timestamp type.  */
200 typedef uint64_t nscd_time_t;
201 
202 /* Maximum timestamp.  */
203 #define MAX_TIMEOUT_VALUE \
204   (sizeof (time_t) == sizeof (long int) ? LONG_MAX : INT_MAX)
205 
206 /* Alignment requirement of the beginning of the data region.  */
207 #define ALIGN 16
208 
209 
210 /* Head of record in data part of database.  */
211 struct datahead
212 {
213   nscd_ssize_t allocsize;	/* Allocated Bytes.  */
214   nscd_ssize_t recsize;		/* Size of the record.  */
215   nscd_time_t timeout;		/* Time when this entry becomes invalid.  */
216   uint8_t notfound;		/* Nonzero if data has not been found.  */
217   uint8_t nreloads;		/* Reloads without use.  */
218   uint8_t usable;		/* False if the entry must be ignored.  */
219   uint8_t unused;		/* Unused.  */
220   uint32_t ttl;			/* TTL value used.  */
221 
222   /* We need to have the following element aligned for the response
223      header data types and their use in the 'struct dataset' types
224      defined in the XXXcache.c files.  */
225   union
226   {
227     pw_response_header pwdata;
228     gr_response_header grdata;
229     hst_response_header hstdata;
230     ai_response_header aidata;
231     initgr_response_header initgrdata;
232     serv_response_header servdata;
233     netgroup_response_header netgroupdata;
234     innetgroup_response_header innetgroupdata;
235     nscd_ssize_t align1;
236     nscd_time_t align2;
237   } data[0];
238 };
239 
240 static inline time_t
datahead_init_common(struct datahead * head,nscd_ssize_t allocsize,nscd_ssize_t recsize,uint32_t ttl)241 datahead_init_common (struct datahead *head, nscd_ssize_t allocsize,
242 		      nscd_ssize_t recsize, uint32_t ttl)
243 {
244   /* Initialize so that we don't write out junk in uninitialized data to the
245      cache.  */
246   memset (head, 0, sizeof (*head));
247 
248   head->allocsize = allocsize;
249   head->recsize = recsize;
250   head->usable = true;
251 
252   head->ttl = ttl;
253 
254   /* Compute and return the timeout time.  */
255   return head->timeout = time (NULL) + ttl;
256 }
257 
258 static inline time_t
datahead_init_pos(struct datahead * head,nscd_ssize_t allocsize,nscd_ssize_t recsize,uint8_t nreloads,uint32_t ttl)259 datahead_init_pos (struct datahead *head, nscd_ssize_t allocsize,
260 		   nscd_ssize_t recsize, uint8_t nreloads, uint32_t ttl)
261 {
262   time_t ret = datahead_init_common (head, allocsize, recsize, ttl);
263 
264   head->notfound = false;
265   head->nreloads = nreloads;
266 
267   return ret;
268 }
269 
270 static inline time_t
datahead_init_neg(struct datahead * head,nscd_ssize_t allocsize,nscd_ssize_t recsize,uint32_t ttl)271 datahead_init_neg (struct datahead *head, nscd_ssize_t allocsize,
272 		   nscd_ssize_t recsize, uint32_t ttl)
273 {
274   time_t ret = datahead_init_common (head, allocsize, recsize, ttl);
275 
276   /* We don't need to touch nreloads here since it is set to our desired value
277      (0) when we clear the structure.  */
278   head->notfound = true;
279 
280   return ret;
281 }
282 
283 /* Structure for one hash table entry.  */
284 struct hashentry
285 {
286   request_type type:8;		/* Which type of dataset.  */
287   bool first;			/* True if this was the original key.  */
288   nscd_ssize_t len;		/* Length of key.  */
289   ref_t key;			/* Pointer to key.  */
290   int32_t owner;		/* If secure table, this is the owner.  */
291   ref_t next;			/* Next entry in this hash bucket list.  */
292   ref_t packet;			/* Records for the result.  */
293   union
294   {
295     struct hashentry *dellist;	/* Next record to be deleted.  This can be a
296 				   pointer since only nscd uses this field.  */
297     ref_t *prevp;		/* Pointer to field containing forward
298 				   reference.  */
299   };
300 };
301 
302 
303 /* Current persistent database version.  */
304 #define DB_VERSION	2
305 
306 /* Maximum time allowed between updates of the timestamp.  */
307 #define MAPPING_TIMEOUT (5 * 60)
308 
309 
310 /* Used indices for the EXTRA_DATA element of 'database_pers_head'.
311    Each database has its own indices.  */
312 #define NSCD_HST_IDX_CONF_TIMESTAMP	0
313 
314 
315 /* Header of persistent database file.  */
316 struct database_pers_head
317 {
318   int32_t version;
319   int32_t header_size;
320   volatile int32_t gc_cycle;
321   volatile int32_t nscd_certainly_running;
322   volatile nscd_time_t timestamp;
323   /* Room for extensions.  */
324   volatile uint32_t extra_data[4];
325 
326   nscd_ssize_t module;
327   nscd_ssize_t data_size;
328 
329   nscd_ssize_t first_free;	/* Offset of first free byte in data area.  */
330 
331   nscd_ssize_t nentries;
332   nscd_ssize_t maxnentries;
333   nscd_ssize_t maxnsearched;
334 
335   uint64_t poshit;
336   uint64_t neghit;
337   uint64_t posmiss;
338   uint64_t negmiss;
339 
340   uint64_t rdlockdelayed;
341   uint64_t wrlockdelayed;
342 
343   uint64_t addfailed;
344 
345   ref_t array[0];
346 };
347 
348 
349 /* Mapped database record.  */
350 struct mapped_database
351 {
352   const struct database_pers_head *head;
353   const char *data;
354   size_t mapsize;
355   int counter;		/* > 0 indicates it is usable.  */
356   size_t datasize;
357 };
358 #define NO_MAPPING ((struct mapped_database *) -1l)
359 
360 struct locked_map_ptr
361 {
362   int lock;
363   struct mapped_database *mapped;
364 };
365 #define libc_locked_map_ptr(class, name) class struct locked_map_ptr name
366 
367 /* Try acquiring lock for mapptr, returns true if it succeeds, false
368    if not.  */
369 static inline bool
__nscd_acquire_maplock(volatile struct locked_map_ptr * mapptr)370 __nscd_acquire_maplock (volatile struct locked_map_ptr *mapptr)
371 {
372   int cnt = 0;
373   while (__builtin_expect (atomic_compare_and_exchange_val_acq (&mapptr->lock,
374 								1, 0) != 0, 0))
375     {
376       // XXX Best number of rounds?
377       if (__glibc_unlikely (++cnt > 5))
378 	return false;
379 
380       atomic_spin_nop ();
381     }
382 
383   return true;
384 }
385 
386 
387 /* Open socket connection to nscd server.  */
388 extern int __nscd_open_socket (const char *key, size_t keylen,
389 			       request_type type, void *response,
390 			       size_t responselen) attribute_hidden;
391 
392 /* Try to get a file descriptor for the shared meory segment
393    containing the database.  */
394 extern struct mapped_database *__nscd_get_mapping (request_type type,
395 						   const char *key,
396 						   struct mapped_database **mappedp) attribute_hidden;
397 
398 /* Get reference of mapping.  */
399 extern struct mapped_database *__nscd_get_map_ref (request_type type,
400 						   const char *name,
401 						   volatile struct locked_map_ptr *mapptr,
402 						   int *gc_cyclep)
403   attribute_hidden;
404 
405 /* Unmap database.  */
406 extern void __nscd_unmap (struct mapped_database *mapped)
407   attribute_hidden;
408 
409 /* Drop reference of mapping.  */
410 static int
411 __attribute__ ((unused))
__nscd_drop_map_ref(struct mapped_database * map,int * gc_cycle)412 __nscd_drop_map_ref (struct mapped_database *map, int *gc_cycle)
413 {
414   if (map != NO_MAPPING)
415     {
416       int now_cycle = map->head->gc_cycle;
417       if (__glibc_unlikely (now_cycle != *gc_cycle))
418 	{
419 	  /* We might have read inconsistent data.  */
420 	  *gc_cycle = now_cycle;
421 	  return -1;
422 	}
423 
424       if (atomic_decrement_val (&map->counter) == 0)
425 	__nscd_unmap (map);
426     }
427 
428   return 0;
429 }
430 
431 
432 /* Search the mapped database.  */
433 extern struct datahead *__nscd_cache_search (request_type type,
434 					     const char *key,
435 					     size_t keylen,
436 					     const struct mapped_database *mapped,
437 					     size_t datalen)
438   attribute_hidden;
439 
440 /* Wrappers around read, readv and write that only read/write less than LEN
441    bytes on error or EOF.  */
442 extern ssize_t __readall (int fd, void *buf, size_t len)
443   attribute_hidden;
444 extern ssize_t __readvall (int fd, const struct iovec *iov, int iovcnt)
445   attribute_hidden;
446 extern ssize_t writeall (int fd, const void *buf, size_t len)
447   attribute_hidden;
448 
449 /* Get netlink timestamp counter from mapped area or zero.  */
450 extern uint32_t __nscd_get_nl_timestamp (void)
451   attribute_hidden;
452 
453 #endif /* nscd.h */
454