nscd/nscd-client.h

   1 /* Copyright (c) 1998-2023 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
 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
 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
 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
 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 memory 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))
 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_fetch_add_relaxed (&map->counter, -1) == 1)
 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 */