nscd/nscd_getgr_r.c

   1 /* Copyright (C) 1998-2017 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Thorsten Kukuk <kukuk@uni-paderborn.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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <alloca.h>
  20 #include <assert.h>
  21 #include <errno.h>
  22 #include <grp.h>
  23 #include <stdint.h>
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <unistd.h>
  28 #include <sys/mman.h>
  29 #include <sys/socket.h>
  30 #include <sys/uio.h>
  31 #include <sys/un.h>
  32 #include <not-cancel.h>
  33 #include <_itoa.h>
  34 #include <scratch_buffer.h>
  35
  36 #include "nscd-client.h"
  37 #include "nscd_proto.h"
  38
  39 int __nss_not_use_nscd_group;
  40
  41 static int nscd_getgr_r (const char *key, size_t keylen, request_type type,
  42                          struct group *resultbuf, char *buffer,
  43                          size_t buflen, struct group **result)
  44      internal_function;
  45
  46
  47 int
  48 __nscd_getgrnam_r (const char *name, struct group *resultbuf, char *buffer,
  49                    size_t buflen, struct group **result)
  50 {
  51   return nscd_getgr_r (name, strlen (name) + 1, GETGRBYNAME, resultbuf,
  52                        buffer, buflen, result);
  53 }
  54
  55
  56 int
  57 __nscd_getgrgid_r (gid_t gid, struct group *resultbuf, char *buffer,
  58                    size_t buflen, struct group **result)
  59 {
  60   char buf[3 * sizeof (gid_t)];
  61   buf[sizeof (buf) - 1] = '\0';
  62   char *cp = _itoa_word (gid, buf + sizeof (buf) - 1, 10, 0);
  63
  64   return nscd_getgr_r (cp, buf + sizeof (buf) - cp, GETGRBYGID, resultbuf,
  65                        buffer, buflen, result);
  66 }
  67
  68
  69 libc_locked_map_ptr (,__gr_map_handle) attribute_hidden;
  70 /* Note that we only free the structure if necessary.  The memory
  71    mapping is not removed since it is not visible to the malloc
  72    handling.  */
  73 libc_freeres_fn (gr_map_free)
  74 {
  75   if (__gr_map_handle.mapped != NO_MAPPING)
  76     {
  77       void *p = __gr_map_handle.mapped;
  78       __gr_map_handle.mapped = NO_MAPPING;
  79       free (p);
  80     }
  81 }
  82
  83
  84 static int
  85 internal_function
  86 nscd_getgr_r (const char *key, size_t keylen, request_type type,
  87               struct group *resultbuf, char *buffer, size_t buflen,
  88               struct group **result)
  89 {
  90   int gc_cycle;
  91   int nretries = 0;
  92   const uint32_t *len = NULL;
  93   struct scratch_buffer lenbuf;
  94   scratch_buffer_init (&lenbuf);
  95
  96   /* If the mapping is available, try to search there instead of
  97      communicating with the nscd.  */
  98   struct mapped_database *mapped = __nscd_get_map_ref (GETFDGR, "group",
  99                                                        &__gr_map_handle,
 100                                                        &gc_cycle);
 101  retry:;
 102   const char *gr_name = NULL;
 103   size_t gr_name_len = 0;
 104   int retval = -1;
 105   const char *recend = (const char *) ~UINTMAX_C (0);
 106   gr_response_header gr_resp;
 107
 108   if (mapped != NO_MAPPING)
 109     {
 110       struct datahead *found = __nscd_cache_search (type, key, keylen, mapped,
 111                                                     sizeof gr_resp);
 112       if (found != NULL)
 113         {
 114           len = (const uint32_t *) (&found->data[0].grdata + 1);
 115           gr_resp = found->data[0].grdata;
 116           gr_name = ((const char *) len
 117                      + gr_resp.gr_mem_cnt * sizeof (uint32_t));
 118           gr_name_len = gr_resp.gr_name_len + gr_resp.gr_passwd_len;
 119           recend = (const char *) found->data + found->recsize;
 120           /* Now check if we can trust gr_resp fields.  If GC is
 121              in progress, it can contain anything.  */
 122           if (mapped->head->gc_cycle != gc_cycle)
 123             {
 124               retval = -2;
 125               goto out;
 126             }
 127
 128           /* The alignment is always sufficient, unless GC is in progress.  */
 129           assert (((uintptr_t) len & (__alignof__ (*len) - 1)) == 0);
 130         }
 131     }
 132
 133   int sock = -1;
 134   if (gr_name == NULL)
 135     {
 136       sock = __nscd_open_socket (key, keylen, type, &gr_resp,
 137                                  sizeof (gr_resp));
 138       if (sock == -1)
 139         {
 140           __nss_not_use_nscd_group = 1;
 141           goto out;
 142         }
 143     }
 144
 145   /* No value found so far.  */
 146   *result = NULL;
 147
 148   if (__glibc_unlikely (gr_resp.found == -1))
 149     {
 150       /* The daemon does not cache this database.  */
 151       __nss_not_use_nscd_group = 1;
 152       goto out_close;
 153     }
 154
 155   if (gr_resp.found == 1)
 156     {
 157       struct iovec vec[2];
 158       char *p = buffer;
 159       size_t total_len;
 160       uintptr_t align;
 161       nscd_ssize_t cnt;
 162
 163       /* Now allocate the buffer the array for the group members.  We must
 164          align the pointer.  */
 165       align = ((__alignof__ (char *) - (p - ((char *) 0)))
 166                & (__alignof__ (char *) - 1));
 167       total_len = (align + (1 + gr_resp.gr_mem_cnt) * sizeof (char *)
 168                    + gr_resp.gr_name_len + gr_resp.gr_passwd_len);
 169       if (__glibc_unlikely (buflen < total_len))
 170         {
 171         no_room:
 172           __set_errno (ERANGE);
 173           retval = ERANGE;
 174           goto out_close;
 175         }
 176       buflen -= total_len;
 177
 178       p += align;
 179       resultbuf->gr_mem = (char **) p;
 180       p += (1 + gr_resp.gr_mem_cnt) * sizeof (char *);
 181
 182       /* Set pointers for strings.  */
 183       resultbuf->gr_name = p;
 184       p += gr_resp.gr_name_len;
 185       resultbuf->gr_passwd = p;
 186       p += gr_resp.gr_passwd_len;
 187
 188       /* Fill in what we know now.  */
 189       resultbuf->gr_gid = gr_resp.gr_gid;
 190
 191       /* Read the length information, group name, and password.  */
 192       if (gr_name == NULL)
 193         {
 194           /* Handle a simple, usual case: no group members.  */
 195           if (__glibc_likely (gr_resp.gr_mem_cnt == 0))
 196             {
 197               size_t n = gr_resp.gr_name_len + gr_resp.gr_passwd_len;
 198               if (__builtin_expect (__readall (sock, resultbuf->gr_name, n)
 199                                     != (ssize_t) n, 0))
 200                 goto out_close;
 201             }
 202           else
 203             {
 204               /* Allocate array to store lengths.  */
 205               if (!scratch_buffer_set_array_size
 206                   (&lenbuf, gr_resp.gr_mem_cnt, sizeof (uint32_t)))
 207                 goto out_close;
 208               len = lenbuf.data;
 209
 210               vec[0].iov_base = (void *) len;
 211               vec[0].iov_len = gr_resp.gr_mem_cnt * sizeof (uint32_t);
 212               vec[1].iov_base = resultbuf->gr_name;
 213               vec[1].iov_len = gr_resp.gr_name_len + gr_resp.gr_passwd_len;
 214               total_len = vec[0].iov_len + vec[1].iov_len;
 215
 216               /* Get this data.  */
 217               size_t n = __readvall (sock, vec, 2);
 218               if (__glibc_unlikely (n != total_len))
 219                 goto out_close;
 220             }
 221         }
 222       else
 223         /* We already have the data.  Just copy the group name and
 224            password.  */
 225         memcpy (resultbuf->gr_name, gr_name,
 226                 gr_resp.gr_name_len + gr_resp.gr_passwd_len);
 227
 228       /* Clear the terminating entry.  */
 229       resultbuf->gr_mem[gr_resp.gr_mem_cnt] = NULL;
 230
 231       /* Prepare reading the group members.  */
 232       total_len = 0;
 233       for (cnt = 0; cnt < gr_resp.gr_mem_cnt; ++cnt)
 234         {
 235           resultbuf->gr_mem[cnt] = p;
 236           total_len += len[cnt];
 237           p += len[cnt];
 238         }
 239
 240       if (__glibc_unlikely (gr_name + gr_name_len + total_len > recend))
 241         {
 242           /* len array might contain garbage during nscd GC cycle,
 243              retry rather than fail in that case.  */
 244           if (gr_name != NULL && mapped->head->gc_cycle != gc_cycle)
 245             retval = -2;
 246           goto out_close;
 247         }
 248       if (__glibc_unlikely (total_len > buflen))
 249         {
 250           /* len array might contain garbage during nscd GC cycle,
 251              retry rather than fail in that case.  */
 252           if (gr_name != NULL && mapped->head->gc_cycle != gc_cycle)
 253             {
 254               retval = -2;
 255               goto out_close;
 256             }
 257           else
 258             goto no_room;
 259         }
 260
 261       retval = 0;
 262
 263       /* If there are no group members TOTAL_LEN is zero.  */
 264       if (gr_name == NULL)
 265         {
 266           if (total_len > 0
 267               && __builtin_expect (__readall (sock, resultbuf->gr_mem[0],
 268                                               total_len) != total_len, 0))
 269             {
 270               /* The `errno' to some value != ERANGE.  */
 271               __set_errno (ENOENT);
 272               retval = ENOENT;
 273             }
 274           else
 275             *result = resultbuf;
 276         }
 277       else
 278         {
 279           /* Copy the group member names.  */
 280           memcpy (resultbuf->gr_mem[0], gr_name + gr_name_len, total_len);
 281
 282           /* Try to detect corrupt databases.  */
 283           if (resultbuf->gr_name[gr_name_len - 1] != '\0'
 284               || resultbuf->gr_passwd[gr_resp.gr_passwd_len - 1] != '\0'
 285               || ({for (cnt = 0; cnt < gr_resp.gr_mem_cnt; ++cnt)
 286                     if (resultbuf->gr_mem[cnt][len[cnt] - 1] != '\0')
 287                       break;
 288                   cnt < gr_resp.gr_mem_cnt; }))
 289             {
 290               /* We cannot use the database.  */
 291               retval = mapped->head->gc_cycle != gc_cycle ? -2 : -1;
 292               goto out_close;
 293             }
 294
 295           *result = resultbuf;
 296         }
 297     }
 298   else
 299     {
 300       /* Set errno to 0 to indicate no error, just no found record.  */
 301       __set_errno (0);
 302       /* Even though we have not found anything, the result is zero.  */
 303       retval = 0;
 304     }
 305
 306  out_close:
 307   if (sock != -1)
 308     __close_nocancel_nostatus (sock);
 309  out:
 310   if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
 311     {
 312       /* When we come here this means there has been a GC cycle while we
 313          were looking for the data.  This means the data might have been
 314          inconsistent.  Retry if possible.  */
 315       if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
 316         {
 317           /* nscd is just running gc now.  Disable using the mapping.  */
 318           if (atomic_decrement_val (&mapped->counter) == 0)
 319             __nscd_unmap (mapped);
 320           mapped = NO_MAPPING;
 321         }
 322
 323       if (retval != -1)
 324         goto retry;
 325     }
 326
 327   scratch_buffer_free (&lenbuf);
 328
 329   return retval;
 330 }