nss/getXXbyYY_r.c

   1 /* Copyright (C) 1996-2022 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 #include <assert.h>
  19 #include <atomic.h>
  20 #include <errno.h>
  21 #include <stdbool.h>
  22 #include "nsswitch.h"
  23 #include "sysdep.h"
  24 #ifdef USE_NSCD
  25 # include <nscd/nscd_proto.h>
  26 #endif
  27 #ifdef NEED__RES
  28 # include <resolv/resolv_context.h>
  29 #endif
  30 /*******************************************************************\
  31 |* Here we assume several symbols to be defined:                   *|
  32 |*                                                                 *|
  33 |* LOOKUP_TYPE   - the return type of the function                 *|
  34 |*                                                                 *|
  35 |* FUNCTION_NAME - name of the non-reentrant function              *|
  36 |*                                                                 *|
  37 |* DATABASE_NAME - name of the database the function accesses      *|
  38 |*                 (e.g., host, services, ...)                     *|
  39 |*                                                                 *|
  40 |* ADD_PARAMS    - additional parameters, can vary in number       *|
  41 |*                                                                 *|
  42 |* ADD_VARIABLES - names of additional parameters                  *|
  43 |*                                                                 *|
  44 |* Optionally the following vars can be defined:                   *|
  45 |*                                                                 *|
  46 |* EXTRA_PARAMS  - optional parameters, can vary in number         *|
  47 |*                                                                 *|
  48 |* EXTRA_VARIABLES - names of optional parameter                   *|
  49 |*                                                                 *|
  50 |* FUNCTION2_NAME - alternative name of the non-reentrant function *|
  51 |*                                                                 *|
  52 |* NEED_H_ERRNO  - an extra parameter will be passed to point to   *|
  53 |*                 the global `h_errno' variable.                  *|
  54 |*                                                                 *|
  55 |* NEED__RES     - obtain a struct resolv_context resolver context *|
  56 |*                                                                 *|
  57 |* PREPROCESS    - code run before anything else                   *|
  58 |*                                                                 *|
  59 |* POSTPROCESS   - code run after the lookup                       *|
  60 |*                                                                 *|
  61 \*******************************************************************/
  62
  63 /* To make the real sources a bit prettier.  */
  64 #define REENTRANT_NAME APPEND_R (FUNCTION_NAME)
  65 #ifdef FUNCTION2_NAME
  66 # define REENTRANT2_NAME APPEND_R (FUNCTION2_NAME)
  67 #else
  68 # define REENTRANT2_NAME NULL
  69 #endif
  70 #define APPEND_R(name) APPEND_R1 (name)
  71 #define APPEND_R1(name) name##_r
  72 #define INTERNAL(name) INTERNAL1 (name)
  73 #define INTERNAL1(name) __##name
  74 #define NEW(name) NEW1 (name)
  75 #define NEW1(name) __new_##name
  76
  77 #ifdef USE_NSCD
  78 # define NSCD_NAME ADD_NSCD (REENTRANT_NAME)
  79 # define ADD_NSCD(name) ADD_NSCD1 (name)
  80 # define ADD_NSCD1(name) __nscd_##name
  81 # define NOT_USENSCD_NAME ADD_NOT_NSCDUSE (DATABASE_NAME)
  82 # define ADD_NOT_NSCDUSE(name) ADD_NOT_NSCDUSE1 (name)
  83 # define ADD_NOT_NSCDUSE1(name) __nss_not_use_nscd_##name
  84 # define CONCAT2(arg1, arg2) CONCAT2_2 (arg1, arg2)
  85 # define CONCAT2_2(arg1, arg2) arg1##arg2
  86 #endif
  87
  88 #define FUNCTION_NAME_STRING STRINGIZE (FUNCTION_NAME)
  89 #define REENTRANT_NAME_STRING STRINGIZE (REENTRANT_NAME)
  90 #ifdef FUNCTION2_NAME
  91 # define REENTRANT2_NAME_STRING STRINGIZE (REENTRANT2_NAME)
  92 #else
  93 # define REENTRANT2_NAME_STRING NULL
  94 #endif
  95 #define DATABASE_NAME_STRING STRINGIZE (DATABASE_NAME)
  96 #define STRINGIZE(name) STRINGIZE1 (name)
  97 #define STRINGIZE1(name) #name
  98
  99 #ifndef DB_LOOKUP_FCT
 100 # define DB_LOOKUP_FCT CONCAT3_1 (__nss_, DATABASE_NAME, _lookup2)
 101 # define CONCAT3_1(Pre, Name, Post) CONCAT3_2 (Pre, Name, Post)
 102 # define CONCAT3_2(Pre, Name, Post) Pre##Name##Post
 103 #endif
 104
 105 /* Sometimes we need to store error codes in the `h_errno' variable.  */
 106 #ifdef NEED_H_ERRNO
 107 # define H_ERRNO_PARM , int *h_errnop
 108 # define H_ERRNO_VAR , h_errnop
 109 # define H_ERRNO_VAR_P h_errnop
 110 #else
 111 # define H_ERRNO_PARM
 112 # define H_ERRNO_VAR
 113 # define H_ERRNO_VAR_P NULL
 114 #endif
 115
 116 #ifndef EXTRA_PARAMS
 117 # define EXTRA_PARAMS
 118 #endif
 119 #ifndef EXTRA_VARIABLES
 120 # define EXTRA_VARIABLES
 121 #endif
 122
 123 #ifdef HAVE_AF
 124 # define AF_VAL af
 125 #else
 126 # define AF_VAL AF_INET
 127 #endif
 128
 129
 130 /* Set defaults for merge functions that haven't been defined.  */
 131 #ifndef DEEPCOPY_FN
 132 static inline int
 133 __copy_einval (LOOKUP_TYPE a,
 134                const size_t b,
 135                LOOKUP_TYPE *c,
 136                char *d,
 137                char **e)
 138 {
 139   return EINVAL;
 140 }
 141 # define DEEPCOPY_FN __copy_einval
 142 #endif
 143
 144 #ifndef MERGE_FN
 145 static inline int
 146 __merge_einval (LOOKUP_TYPE *a,
 147                 char *b,
 148                 char *c,
 149                 size_t d,
 150                 LOOKUP_TYPE *e,
 151                 char *f)
 152 {
 153   return EINVAL;
 154 }
 155 # define MERGE_FN __merge_einval
 156 #endif
 157
 158 #define CHECK_MERGE(err, status)                \
 159   ({                                            \
 160     do                                          \
 161       {                                         \
 162         if (err)                                \
 163           {                                     \
 164             __set_errno (err);                  \
 165             if (err == ERANGE)                  \
 166               status = NSS_STATUS_TRYAGAIN;     \
 167             else                                \
 168               status = NSS_STATUS_UNAVAIL;      \
 169             break;                              \
 170           }                                     \
 171       }                                         \
 172     while (0);                                  \
 173   })
 174
 175 /* Type of the lookup function we need here.  */
 176 typedef enum nss_status (*lookup_function) (ADD_PARAMS, LOOKUP_TYPE *, char *,
 177                                             size_t, int * H_ERRNO_PARM
 178                                             EXTRA_PARAMS);
 179
 180 /* The lookup function for the first entry of this service.  */
 181 extern int DB_LOOKUP_FCT (nss_action_list *nip, const char *name,
 182                           const char *name2, void **fctp);
 183 libc_hidden_proto (DB_LOOKUP_FCT)
 184
 185
 186 int
 187 INTERNAL (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,
 188                            size_t buflen, LOOKUP_TYPE **result H_ERRNO_PARM
 189                            EXTRA_PARAMS)
 190 {
 191   nss_action_list nip;
 192   int do_merge = 0;
 193   LOOKUP_TYPE mergegrp;
 194   char *mergebuf = NULL;
 195   char *endptr = NULL;
 196   union
 197   {
 198     lookup_function l;
 199     void *ptr;
 200   } fct;
 201   int no_more, err;
 202   enum nss_status status = NSS_STATUS_UNAVAIL;
 203 #ifdef USE_NSCD
 204   int nscd_status;
 205 #endif
 206 #ifdef NEED_H_ERRNO
 207   bool any_service = false;
 208 #endif
 209
 210 #ifdef NEED__RES
 211   /* The HANDLE_DIGITS_DOTS case below already needs the resolver
 212      configuration, so this has to happen early.  */
 213   struct resolv_context *res_ctx = __resolv_context_get ();
 214   if (res_ctx == NULL)
 215     {
 216       *h_errnop = NETDB_INTERNAL;
 217       *result = NULL;
 218       return errno;
 219     }
 220 #endif /* NEED__RES */
 221
 222 #ifdef PREPROCESS
 223   PREPROCESS;
 224 #endif
 225
 226
 227 #ifdef HANDLE_DIGITS_DOTS
 228   switch (__nss_hostname_digits_dots (name, resbuf, &buffer, NULL,
 229                                       buflen, result, &status, AF_VAL,
 230                                       H_ERRNO_VAR_P))
 231     {
 232     case -1:
 233 # ifdef NEED__RES
 234       __resolv_context_put (res_ctx);
 235 # endif
 236       return errno;
 237     case 1:
 238 #ifdef NEED_H_ERRNO
 239       any_service = true;
 240 #endif
 241       goto done;
 242     }
 243 #endif
 244
 245 #ifdef USE_NSCD
 246   if (NOT_USENSCD_NAME > 0 && ++NOT_USENSCD_NAME > NSS_NSCD_RETRY)
 247     NOT_USENSCD_NAME = 0;
 248
 249   if (!NOT_USENSCD_NAME
 250       && !__nss_database_custom[CONCAT2 (NSS_DBSIDX_, DATABASE_NAME)])
 251     {
 252       nscd_status = NSCD_NAME (ADD_VARIABLES, resbuf, buffer, buflen, result
 253                                H_ERRNO_VAR);
 254       if (nscd_status >= 0)
 255         {
 256 # ifdef NEED__RES
 257           __resolv_context_put (res_ctx);
 258 # endif
 259           return nscd_status;
 260         }
 261     }
 262 #endif
 263
 264   no_more = DB_LOOKUP_FCT (&nip, REENTRANT_NAME_STRING,
 265                            REENTRANT2_NAME_STRING, &fct.ptr);
 266
 267   while (no_more == 0)
 268     {
 269 #ifdef NEED_H_ERRNO
 270       any_service = true;
 271 #endif
 272
 273       status = DL_CALL_FCT (fct.l, (ADD_VARIABLES, resbuf, buffer, buflen,
 274                                     &errno H_ERRNO_VAR EXTRA_VARIABLES));
 275
 276       /* The status is NSS_STATUS_TRYAGAIN and errno is ERANGE the
 277          provided buffer is too small.  In this case we should give
 278          the user the possibility to enlarge the buffer and we should
 279          not simply go on with the next service (even if the TRYAGAIN
 280          action tells us so).  */
 281       if (status == NSS_STATUS_TRYAGAIN
 282 #ifdef NEED_H_ERRNO
 283           && *h_errnop == NETDB_INTERNAL
 284 #endif
 285           && errno == ERANGE)
 286         break;
 287
 288       if (do_merge)
 289         {
 290
 291           if (status == NSS_STATUS_SUCCESS)
 292             {
 293               /* The previous loop saved a buffer for merging.
 294                  Perform the merge now.  */
 295               err = MERGE_FN (&mergegrp, mergebuf, endptr, buflen, resbuf,
 296                               buffer);
 297               CHECK_MERGE (err,status);
 298               do_merge = 0;
 299             }
 300           else
 301             {
 302               /* If the result wasn't SUCCESS, copy the saved buffer back
 303                  into the result buffer and set the status back to
 304                  NSS_STATUS_SUCCESS to match the previous pass through the
 305                  loop.
 306                   * If the next action is CONTINUE, it will overwrite the value
 307                     currently in the buffer and return the new value.
 308                   * If the next action is RETURN, we'll return the previously-
 309                     acquired values.
 310                   * If the next action is MERGE, then it will be added to the
 311                     buffer saved from the previous source.  */
 312               err = DEEPCOPY_FN (mergegrp, buflen, resbuf, buffer, NULL);
 313               CHECK_MERGE (err, status);
 314               status = NSS_STATUS_SUCCESS;
 315             }
 316         }
 317
 318       /* If we were are configured to merge this value with the next one,
 319          save the current value of the group struct.  */
 320       if (nss_next_action (nip, status) == NSS_ACTION_MERGE
 321           && status == NSS_STATUS_SUCCESS)
 322         {
 323           /* Copy the current values into a buffer to be merged with the next
 324              set of retrieved values.  */
 325           if (mergebuf == NULL)
 326             {
 327               /* Only allocate once and reuse it for as many merges as we need
 328                  to perform.  */
 329               mergebuf = malloc (buflen);
 330               if (mergebuf == NULL)
 331                 {
 332                   __set_errno (ENOMEM);
 333                   status = NSS_STATUS_UNAVAIL;
 334                   break;
 335                 }
 336             }
 337
 338           err = DEEPCOPY_FN (*resbuf, buflen, &mergegrp, mergebuf, &endptr);
 339           CHECK_MERGE (err, status);
 340           do_merge = 1;
 341         }
 342
 343       no_more = __nss_next2 (&nip, REENTRANT_NAME_STRING,
 344                              REENTRANT2_NAME_STRING, &fct.ptr, status, 0);
 345     }
 346   free (mergebuf);
 347   mergebuf = NULL;
 348
 349 #ifdef HANDLE_DIGITS_DOTS
 350 done:
 351 #endif
 352   *result = status == NSS_STATUS_SUCCESS ? resbuf : NULL;
 353 #ifdef NEED_H_ERRNO
 354   if (status == NSS_STATUS_UNAVAIL && !any_service && errno != ENOENT)
 355     /* This happens when we weren't able to use a service for reasons other
 356        than the module not being found.  In such a case, we'd want to tell the
 357        caller that errno has the real reason for failure.  */
 358     *h_errnop = NETDB_INTERNAL;
 359   else if (status != NSS_STATUS_SUCCESS && !any_service)
 360     /* We were not able to use any service.  */
 361     *h_errnop = NO_RECOVERY;
 362 #endif
 363 #ifdef POSTPROCESS
 364   POSTPROCESS;
 365 #endif
 366
 367 #ifdef NEED__RES
 368   /* This has to happen late because the POSTPROCESS stage above might
 369      need the resolver context.  */
 370   __resolv_context_put (res_ctx);
 371 #endif /* NEED__RES */
 372
 373   int res;
 374   if (status == NSS_STATUS_SUCCESS || status == NSS_STATUS_NOTFOUND)
 375     res = 0;
 376   /* Don't pass back ERANGE if this is not for a too-small buffer.  */
 377   else if (errno == ERANGE && status != NSS_STATUS_TRYAGAIN)
 378     res = EINVAL;
 379 #ifdef NEED_H_ERRNO
 380   /* These functions only set errno if h_errno is NETDB_INTERNAL.  */
 381   else if (status == NSS_STATUS_TRYAGAIN && *h_errnop != NETDB_INTERNAL)
 382     res = EAGAIN;
 383 #endif
 384   else
 385     return errno;
 386
 387   __set_errno (res);
 388   return res;
 389 }
 390
 391
 392 #ifdef NO_COMPAT_NEEDED
 393 strong_alias (INTERNAL (REENTRANT_NAME), REENTRANT_NAME);
 394 #elif !defined FUNCTION2_NAME
 395 # include <shlib-compat.h>
 396 # if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1_2)
 397 #  define OLD(name) OLD1 (name)
 398 #  define OLD1(name) __old_##name
 399
 400 int
 401 attribute_compat_text_section
 402 OLD (REENTRANT_NAME) (ADD_PARAMS, LOOKUP_TYPE *resbuf, char *buffer,
 403                       size_t buflen, LOOKUP_TYPE **result H_ERRNO_PARM)
 404 {
 405   int ret = INTERNAL (REENTRANT_NAME) (ADD_VARIABLES, resbuf, buffer,
 406                                        buflen, result H_ERRNO_VAR);
 407
 408   if (ret != 0 || result == NULL)
 409     ret = -1;
 410
 411   return ret;
 412 }
 413
 414 #  define do_symbol_version(real, name, version) \
 415   compat_symbol (libc, real, name, version)
 416 do_symbol_version (OLD (REENTRANT_NAME), REENTRANT_NAME, GLIBC_2_0);
 417 # endif
 418
 419 /* As INTERNAL (REENTRANT_NAME) may be hidden, we need an alias
 420    in between so that the REENTRANT_NAME@@GLIBC_2.1.2 is not
 421    hidden too.  */
 422 strong_alias (INTERNAL (REENTRANT_NAME), NEW (REENTRANT_NAME));
 423
 424 # define do_default_symbol_version(real, name, version) \
 425   versioned_symbol (libc, real, name, version)
 426 do_default_symbol_version (NEW (REENTRANT_NAME),
 427                            REENTRANT_NAME, GLIBC_2_1_2);
 428 #endif
 429
 430 nss_interface_function (REENTRANT_NAME)