nscd/nscd_getgr_r.c

   1 /* Copyright (C) 1998-2000, 2002-2005, 2006, 2007, 2009
   2    Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Thorsten Kukuk <kukuk@uni-paderborn.de>, 1998.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <alloca.h>
  22 #include <assert.h>
  23 #include <errno.h>
  24 #include <grp.h>
  25 #include <stdint.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30 #include <sys/mman.h>
  31 #include <sys/socket.h>
  32 #include <sys/uio.h>
  33 #include <sys/un.h>
  34 #include <not-cancel.h>
  35 #include <stdio-common/_itoa.h>
  36
  37 #include "nscd-client.h"
  38 #include "nscd_proto.h"
  39
  40 int __nss_not_use_nscd_group;
  41
  42 static int nscd_getgr_r (const char *key, size_t keylen, request_type type,
  43                          struct group *resultbuf, char *buffer,
  44                          size_t buflen, struct group **result)
  45      internal_function;
  46
  47
  48 int
  49 __nscd_getgrnam_r (const char *name, struct group *resultbuf, char *buffer,
  50                    size_t buflen, struct group **result)
  51 {
  52   return nscd_getgr_r (name, strlen (name) + 1, GETGRBYNAME, resultbuf,
  53                        buffer, buflen, result);
  54 }
  55
  56
  57 int
  58 __nscd_getgrgid_r (gid_t gid, struct group *resultbuf, char *buffer,
  59                    size_t buflen, struct group **result)
  60 {
  61   char buf[3 * sizeof (gid_t)];
  62   buf[sizeof (buf) - 1] = '\0';
  63   char *cp = _itoa_word (gid, buf + sizeof (buf) - 1, 10, 0);
  64
  65   return nscd_getgr_r (cp, buf + sizeof (buf) - cp, GETGRBYGID, resultbuf,
  66                        buffer, buflen, result);
  67 }
  68
  69
  70 libc_locked_map_ptr (,__gr_map_handle) attribute_hidden;
  71 /* Note that we only free the structure if necessary.  The memory
  72    mapping is not removed since it is not visible to the malloc
  73    handling.  */
  74 libc_freeres_fn (gr_map_free)
  75 {
  76   if (__gr_map_handle.mapped != NO_MAPPING)
  77     {
  78       void *p = __gr_map_handle.mapped;
  79       __gr_map_handle.mapped = NO_MAPPING;
  80       free (p);
  81     }
  82 }
  83
  84
  85 static int
  86 internal_function
  87 nscd_getgr_r (const char *key, size_t keylen, request_type type,
  88               struct group *resultbuf, char *buffer, size_t buflen,
  89               struct group **result)
  90 {
  91   int gc_cycle;
  92   int nretries = 0;
  93   const uint32_t *len = NULL;
  94   size_t lensize = 0;
  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 (__builtin_expect (gr_resp.found == -1, 0))
 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 (__builtin_expect (buflen < total_len, 0))
 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 (__builtin_expect (gr_resp.gr_mem_cnt == 0, 1))
 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 (lensize == 0)
 206                 {
 207                   lensize = gr_resp.gr_mem_cnt * sizeof (uint32_t);
 208                   len = (uint32_t *) alloca (lensize);
 209                 }
 210               else if (gr_resp.gr_mem_cnt * sizeof (uint32_t) > lensize)
 211                 len = extend_alloca (len, lensize,
 212                                      gr_resp.gr_mem_cnt * sizeof (uint32_t));
 213
 214               vec[0].iov_base = (void *) len;
 215               vec[0].iov_len = gr_resp.gr_mem_cnt * sizeof (uint32_t);
 216               vec[1].iov_base = resultbuf->gr_name;
 217               vec[1].iov_len = gr_resp.gr_name_len + gr_resp.gr_passwd_len;
 218               total_len = vec[0].iov_len + vec[1].iov_len;
 219
 220               /* Get this data.  */
 221               size_t n = __readvall (sock, vec, 2);
 222               if (__builtin_expect (n != total_len, 0))
 223                 goto out_close;
 224             }
 225         }
 226       else
 227         /* We already have the data.  Just copy the group name and
 228            password.  */
 229         memcpy (resultbuf->gr_name, gr_name,
 230                 gr_resp.gr_name_len + gr_resp.gr_passwd_len);
 231
 232       /* Clear the terminating entry.  */
 233       resultbuf->gr_mem[gr_resp.gr_mem_cnt] = NULL;
 234
 235       /* Prepare reading the group members.  */
 236       total_len = 0;
 237       for (cnt = 0; cnt < gr_resp.gr_mem_cnt; ++cnt)
 238         {
 239           resultbuf->gr_mem[cnt] = p;
 240           total_len += len[cnt];
 241           p += len[cnt];
 242         }
 243
 244       if (__builtin_expect (gr_name + gr_name_len + total_len > recend, 0))
 245         {
 246           /* len array might contain garbage during nscd GC cycle,
 247              retry rather than fail in that case.  */
 248           if (gr_name != NULL && mapped->head->gc_cycle != gc_cycle)
 249             retval = -2;
 250           goto out_close;
 251         }
 252       if (__builtin_expect (total_len > buflen, 0))
 253         {
 254           /* len array might contain garbage during nscd GC cycle,
 255              retry rather than fail in that case.  */
 256           if (gr_name != NULL && mapped->head->gc_cycle != gc_cycle)
 257             {
 258               retval = -2;
 259               goto out_close;
 260             }
 261           else
 262             goto no_room;
 263         }
 264
 265       retval = 0;
 266
 267       /* If there are no group members TOTAL_LEN is zero.  */
 268       if (gr_name == NULL)
 269         {
 270           if (total_len > 0
 271               && __builtin_expect (__readall (sock, resultbuf->gr_mem[0],
 272                                               total_len) != total_len, 0))
 273             {
 274               /* The `errno' to some value != ERANGE.  */
 275               __set_errno (ENOENT);
 276               retval = ENOENT;
 277             }
 278           else
 279             *result = resultbuf;
 280         }
 281       else
 282         {
 283           /* Copy the group member names.  */
 284           memcpy (resultbuf->gr_mem[0], gr_name + gr_name_len, total_len);
 285
 286           /* Try to detect corrupt databases.  */
 287           if (resultbuf->gr_name[gr_name_len - 1] != '\0'
 288               || resultbuf->gr_passwd[gr_resp.gr_passwd_len - 1] != '\0'
 289               || ({for (cnt = 0; cnt < gr_resp.gr_mem_cnt; ++cnt)
 290                     if (resultbuf->gr_mem[cnt][len[cnt] - 1] != '\0')
 291                       break;
 292                   cnt < gr_resp.gr_mem_cnt; }))
 293             {
 294               /* We cannot use the database.  */
 295               retval = mapped->head->gc_cycle != gc_cycle ? -2 : -1;
 296               goto out_close;
 297             }
 298
 299           *result = resultbuf;
 300         }
 301     }
 302   else
 303     {
 304       /* Set errno to 0 to indicate no error, just no found record.  */
 305       __set_errno (0);
 306       /* Even though we have not found anything, the result is zero.  */
 307       retval = 0;
 308     }
 309
 310  out_close:
 311   if (sock != -1)
 312     close_not_cancel_no_status (sock);
 313  out:
 314   if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
 315     {
 316       /* When we come here this means there has been a GC cycle while we
 317          were looking for the data.  This means the data might have been
 318          inconsistent.  Retry if possible.  */
 319       if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
 320         {
 321           /* nscd is just running gc now.  Disable using the mapping.  */
 322           if (atomic_decrement_val (&mapped->counter) == 0)
 323             __nscd_unmap (mapped);
 324           mapped = NO_MAPPING;
 325         }
 326
 327       if (retval != -1)
 328         goto retry;
 329     }
 330
 331   return retval;
 332 }