1/* Copyright (c) 1998-2020 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Thorsten Kukuk <kukuk@suse.de>, 1998.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19/* This file defines everything that client code should need to
20 know to talk to the nscd daemon. */
21
22#ifndef _NSCD_CLIENT_H
23#define _NSCD_CLIENT_H 1
24
25#include <stdbool.h>
26#include <stdint.h>
27#include <string.h>
28#include <time.h>
29#include <sys/types.h>
30#include <atomic.h>
31#include <nscd-types.h>
32#include <sys/uio.h>
33
34
35/* Version number of the daemon interface */
36#define NSCD_VERSION 2
37
38/* Path of the file where the PID of the running system is stored. */
39#define _PATH_NSCDPID "/var/run/nscd/nscd.pid"
40
41/* Path for the Unix domain socket. */
42#define _PATH_NSCDSOCKET "/var/run/nscd/socket"
43
44/* Path for the configuration file. */
45#define _PATH_NSCDCONF "/etc/nscd.conf"
46
47/* Maximum allowed length for the key. */
48#define MAXKEYLEN 1024
49
50
51/* Available services. */
52typedef enum
53{
54 GETPWBYNAME,
55 GETPWBYUID,
56 GETGRBYNAME,
57 GETGRBYGID,
58 GETHOSTBYNAME,
59 GETHOSTBYNAMEv6,
60 GETHOSTBYADDR,
61 GETHOSTBYADDRv6,
62 SHUTDOWN, /* Shut the server down. */
63 GETSTAT, /* Get the server statistic. */
64 INVALIDATE, /* Invalidate one special cache. */
65 GETFDPW,
66 GETFDGR,
67 GETFDHST,
68 GETAI,
69 INITGROUPS,
70 GETSERVBYNAME,
71 GETSERVBYPORT,
72 GETFDSERV,
73 GETNETGRENT,
74 INNETGR,
75 GETFDNETGR,
76 LASTREQ
77} request_type;
78
79
80/* Header common to all requests */
81typedef struct
82{
83 int32_t version; /* Version number of the daemon interface. */
84 request_type type; /* Service requested. */
85 int32_t key_len; /* Key length. */
86} request_header;
87
88
89/* Structure sent in reply to password query. Note that this struct is
90 sent also if the service is disabled or there is no record found. */
91typedef struct
92{
93 int32_t version;
94 int32_t found;
95 nscd_ssize_t pw_name_len;
96 nscd_ssize_t pw_passwd_len;
97 uid_t pw_uid;
98 gid_t pw_gid;
99 nscd_ssize_t pw_gecos_len;
100 nscd_ssize_t pw_dir_len;
101 nscd_ssize_t pw_shell_len;
102} pw_response_header;
103
104
105/* Structure sent in reply to group query. Note that this struct is
106 sent also if the service is disabled or there is no record found. */
107typedef struct
108{
109 int32_t version;
110 int32_t found;
111 nscd_ssize_t gr_name_len;
112 nscd_ssize_t gr_passwd_len;
113 gid_t gr_gid;
114 nscd_ssize_t gr_mem_cnt;
115} gr_response_header;
116
117
118/* Structure sent in reply to host query. Note that this struct is
119 sent also if the service is disabled or there is no record found. */
120typedef struct
121{
122 int32_t version;
123 int32_t found;
124 nscd_ssize_t h_name_len;
125 nscd_ssize_t h_aliases_cnt;
126 int32_t h_addrtype;
127 int32_t h_length;
128 nscd_ssize_t h_addr_list_cnt;
129 int32_t error;
130} hst_response_header;
131
132
133/* Structure sent in reply to addrinfo query. Note that this struct is
134 sent also if the service is disabled or there is no record found. */
135typedef struct
136{
137 int32_t version;
138 int32_t found;
139 nscd_ssize_t naddrs;
140 nscd_ssize_t addrslen;
141 nscd_ssize_t canonlen;
142 int32_t error;
143} ai_response_header;
144
145/* Structure filled in by __nscd_getai. */
146struct nscd_ai_result
147{
148 int naddrs;
149 char *canon;
150 uint8_t *family;
151 char *addrs;
152};
153
154/* Structure sent in reply to initgroups query. Note that this struct is
155 sent also if the service is disabled or there is no record found. */
156typedef struct
157{
158 int32_t version;
159 int32_t found;
160 nscd_ssize_t ngrps;
161} initgr_response_header;
162
163
164/* Structure sent in reply to services query. Note that this struct is
165 sent also if the service is disabled or there is no record found. */
166typedef struct
167{
168 int32_t version;
169 int32_t found;
170 nscd_ssize_t s_name_len;
171 nscd_ssize_t s_proto_len;
172 nscd_ssize_t s_aliases_cnt;
173 int32_t s_port;
174} serv_response_header;
175
176
177/* Structure send in reply to netgroup query. Note that this struct is
178 sent also if the service is disabled or there is no record found. */
179typedef struct
180{
181 int32_t version;
182 int32_t found;
183 nscd_ssize_t nresults;
184 nscd_ssize_t result_len;
185} netgroup_response_header;
186
187typedef struct
188{
189 int32_t version;
190 int32_t found;
191 int32_t result;
192} innetgroup_response_header;
193
194
195/* Type for offsets in data part of database. */
196typedef uint32_t ref_t;
197/* Value for invalid/no reference. */
198#define ENDREF UINT32_MAX
199
200/* Timestamp type. */
201typedef uint64_t nscd_time_t;
202
203/* Maximum timestamp. */
204#define MAX_TIMEOUT_VALUE \
205 (sizeof (time_t) == sizeof (long int) ? LONG_MAX : INT_MAX)
206
207/* Alignment requirement of the beginning of the data region. */
208#define ALIGN 16
209
210
211/* Head of record in data part of database. */
212struct datahead
213{
214 nscd_ssize_t allocsize; /* Allocated Bytes. */
215 nscd_ssize_t recsize; /* Size of the record. */
216 nscd_time_t timeout; /* Time when this entry becomes invalid. */
217 uint8_t notfound; /* Nonzero if data has not been found. */
218 uint8_t nreloads; /* Reloads without use. */
219 uint8_t usable; /* False if the entry must be ignored. */
220 uint8_t unused; /* Unused. */
221 uint32_t ttl; /* TTL value used. */
222
223 /* We need to have the following element aligned for the response
224 header data types and their use in the 'struct dataset' types
225 defined in the XXXcache.c files. */
226 union
227 {
228 pw_response_header pwdata;
229 gr_response_header grdata;
230 hst_response_header hstdata;
231 ai_response_header aidata;
232 initgr_response_header initgrdata;
233 serv_response_header servdata;
234 netgroup_response_header netgroupdata;
235 innetgroup_response_header innetgroupdata;
236 nscd_ssize_t align1;
237 nscd_time_t align2;
238 } data[0];
239};
240
241static inline time_t
242datahead_init_common (struct datahead *head, nscd_ssize_t allocsize,
243 nscd_ssize_t recsize, uint32_t ttl)
244{
245 /* Initialize so that we don't write out junk in uninitialized data to the
246 cache. */
247 memset (head, 0, sizeof (*head));
248
249 head->allocsize = allocsize;
250 head->recsize = recsize;
251 head->usable = true;
252
253 head->ttl = ttl;
254
255 /* Compute and return the timeout time. */
256 return head->timeout = time (NULL) + ttl;
257}
258
259static inline time_t
260datahead_init_pos (struct datahead *head, nscd_ssize_t allocsize,
261 nscd_ssize_t recsize, uint8_t nreloads, uint32_t ttl)
262{
263 time_t ret = datahead_init_common (head, allocsize, recsize, ttl);
264
265 head->notfound = false;
266 head->nreloads = nreloads;
267
268 return ret;
269}
270
271static inline time_t
272datahead_init_neg (struct datahead *head, nscd_ssize_t allocsize,
273 nscd_ssize_t recsize, uint32_t ttl)
274{
275 time_t ret = datahead_init_common (head, allocsize, recsize, ttl);
276
277 /* We don't need to touch nreloads here since it is set to our desired value
278 (0) when we clear the structure. */
279 head->notfound = true;
280
281 return ret;
282}
283
284/* Structure for one hash table entry. */
285struct hashentry
286{
287 request_type type:8; /* Which type of dataset. */
288 bool first; /* True if this was the original key. */
289 nscd_ssize_t len; /* Length of key. */
290 ref_t key; /* Pointer to key. */
291 int32_t owner; /* If secure table, this is the owner. */
292 ref_t next; /* Next entry in this hash bucket list. */
293 ref_t packet; /* Records for the result. */
294 union
295 {
296 struct hashentry *dellist; /* Next record to be deleted. This can be a
297 pointer since only nscd uses this field. */
298 ref_t *prevp; /* Pointer to field containing forward
299 reference. */
300 };
301};
302
303
304/* Current persistent database version. */
305#define DB_VERSION 2
306
307/* Maximum time allowed between updates of the timestamp. */
308#define MAPPING_TIMEOUT (5 * 60)
309
310
311/* Used indices for the EXTRA_DATA element of 'database_pers_head'.
312 Each database has its own indices. */
313#define NSCD_HST_IDX_CONF_TIMESTAMP 0
314
315
316/* Header of persistent database file. */
317struct database_pers_head
318{
319 int32_t version;
320 int32_t header_size;
321 volatile int32_t gc_cycle;
322 volatile int32_t nscd_certainly_running;
323 volatile nscd_time_t timestamp;
324 /* Room for extensions. */
325 volatile uint32_t extra_data[4];
326
327 nscd_ssize_t module;
328 nscd_ssize_t data_size;
329
330 nscd_ssize_t first_free; /* Offset of first free byte in data area. */
331
332 nscd_ssize_t nentries;
333 nscd_ssize_t maxnentries;
334 nscd_ssize_t maxnsearched;
335
336 uint64_t poshit;
337 uint64_t neghit;
338 uint64_t posmiss;
339 uint64_t negmiss;
340
341 uint64_t rdlockdelayed;
342 uint64_t wrlockdelayed;
343
344 uint64_t addfailed;
345
346 ref_t array[0];
347};
348
349
350/* Mapped database record. */
351struct mapped_database
352{
353 const struct database_pers_head *head;
354 const char *data;
355 size_t mapsize;
356 int counter; /* > 0 indicates it is usable. */
357 size_t datasize;
358};
359#define NO_MAPPING ((struct mapped_database *) -1l)
360
361struct locked_map_ptr
362{
363 int lock;
364 struct mapped_database *mapped;
365};
366#define libc_locked_map_ptr(class, name) class struct locked_map_ptr name
367
368/* Try acquiring lock for mapptr, returns true if it succeeds, false
369 if not. */
370static inline bool
371__nscd_acquire_maplock (volatile struct locked_map_ptr *mapptr)
372{
373 int cnt = 0;
374 while (__builtin_expect (atomic_compare_and_exchange_val_acq (&mapptr->lock,
375 1, 0) != 0, 0))
376 {
377 // XXX Best number of rounds?
378 if (__glibc_unlikely (++cnt > 5))
379 return false;
380
381 atomic_spin_nop ();
382 }
383
384 return true;
385}
386
387
388/* Open socket connection to nscd server. */
389extern int __nscd_open_socket (const char *key, size_t keylen,
390 request_type type, void *response,
391 size_t responselen) attribute_hidden;
392
393/* Try to get a file descriptor for the shared meory segment
394 containing the database. */
395extern struct mapped_database *__nscd_get_mapping (request_type type,
396 const char *key,
397 struct mapped_database **mappedp) attribute_hidden;
398
399/* Get reference of mapping. */
400extern struct mapped_database *__nscd_get_map_ref (request_type type,
401 const char *name,
402 volatile struct locked_map_ptr *mapptr,
403 int *gc_cyclep)
404 attribute_hidden;
405
406/* Unmap database. */
407extern void __nscd_unmap (struct mapped_database *mapped)
408 attribute_hidden;
409
410/* Drop reference of mapping. */
411static int
412__attribute__ ((unused))
413__nscd_drop_map_ref (struct mapped_database *map, int *gc_cycle)
414{
415 if (map != NO_MAPPING)
416 {
417 int now_cycle = map->head->gc_cycle;
418 if (__glibc_unlikely (now_cycle != *gc_cycle))
419 {
420 /* We might have read inconsistent data. */
421 *gc_cycle = now_cycle;
422 return -1;
423 }
424
425 if (atomic_decrement_val (&map->counter) == 0)
426 __nscd_unmap (map);
427 }
428
429 return 0;
430}
431
432
433/* Search the mapped database. */
434extern struct datahead *__nscd_cache_search (request_type type,
435 const char *key,
436 size_t keylen,
437 const struct mapped_database *mapped,
438 size_t datalen)
439 attribute_hidden;
440
441/* Wrappers around read, readv and write that only read/write less than LEN
442 bytes on error or EOF. */
443extern ssize_t __readall (int fd, void *buf, size_t len)
444 attribute_hidden;
445extern ssize_t __readvall (int fd, const struct iovec *iov, int iovcnt)
446 attribute_hidden;
447extern ssize_t writeall (int fd, const void *buf, size_t len)
448 attribute_hidden;
449
450/* Get netlink timestamp counter from mapped area or zero. */
451extern uint32_t __nscd_get_nl_timestamp (void)
452 attribute_hidden;
453
454#endif /* nscd.h */
455