nscd/nscd_getgr_r.c

   1 /* Copyright (C) 1998-2000, 2002-2005, 2006, 2007
   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       if (found != NULL)
 112         {
 113           len = (const uint32_t *) (&found->data[0].grdata + 1);
 114           gr_resp = found->data[0].grdata;
 115           gr_name = ((const char *) len
 116                      + gr_resp.gr_mem_cnt * sizeof (uint32_t));
 117           gr_name_len = gr_resp.gr_name_len + gr_resp.gr_passwd_len;
 118           recend = (const char *) found->data + found->recsize;
 119           /* Now check if we can trust gr_resp fields.  If GC is
 120              in progress, it can contain anything.  */
 121           if (mapped->head->gc_cycle != gc_cycle)
 122             {
 123               retval = -2;
 124               goto out;
 125             }
 126
 127           /* The alignment is always sufficient, unless GC is in progress.  */
 128           assert (((uintptr_t) len & (__alignof__ (*len) - 1)) == 0);
 129         }
 130     }
 131
 132   int sock = -1;
 133   if (gr_name == NULL)
 134     {
 135       sock = __nscd_open_socket (key, keylen, type, &gr_resp,
 136                                  sizeof (gr_resp));
 137       if (sock == -1)
 138         {
 139           __nss_not_use_nscd_group = 1;
 140           goto out;
 141         }
 142     }
 143
 144   /* No value found so far.  */
 145   *result = NULL;
 146
 147   if (__builtin_expect (gr_resp.found == -1, 0))
 148     {
 149       /* The daemon does not cache this database.  */
 150       __nss_not_use_nscd_group = 1;
 151       goto out_close;
 152     }
 153
 154   if (gr_resp.found == 1)
 155     {
 156       struct iovec vec[2];
 157       char *p = buffer;
 158       size_t total_len;
 159       uintptr_t align;
 160       nscd_ssize_t cnt;
 161
 162       /* Now allocate the buffer the array for the group members.  We must
 163          align the pointer.  */
 164       align = ((__alignof__ (char *) - (p - ((char *) 0)))
 165                & (__alignof__ (char *) - 1));
 166       total_len = (align + (1 + gr_resp.gr_mem_cnt) * sizeof (char *)
 167                    + gr_resp.gr_name_len + gr_resp.gr_passwd_len);
 168       if (__builtin_expect (buflen < total_len, 0))
 169         {
 170         no_room:
 171           __set_errno (ERANGE);
 172           retval = ERANGE;
 173           goto out_close;
 174         }
 175       buflen -= total_len;
 176
 177       p += align;
 178       resultbuf->gr_mem = (char **) p;
 179       p += (1 + gr_resp.gr_mem_cnt) * sizeof (char *);
 180
 181       /* Set pointers for strings.  */
 182       resultbuf->gr_name = p;
 183       p += gr_resp.gr_name_len;
 184       resultbuf->gr_passwd = p;
 185       p += gr_resp.gr_passwd_len;
 186
 187       /* Fill in what we know now.  */
 188       resultbuf->gr_gid = gr_resp.gr_gid;
 189
 190       /* Read the length information, group name, and password.  */
 191       if (gr_name == NULL)
 192         {
 193           /* Handle a simple, usual case: no group members.  */
 194           if (__builtin_expect (gr_resp.gr_mem_cnt == 0, 1))
 195             {
 196               size_t n = gr_resp.gr_name_len + gr_resp.gr_passwd_len;
 197               if (__builtin_expect (__readall (sock, resultbuf->gr_name, n)
 198                                     != (ssize_t) n, 0))
 199                 goto out_close;
 200             }
 201           else
 202             {
 203               /* Allocate array to store lengths.  */
 204               if (lensize == 0)
 205                 {
 206                   lensize = gr_resp.gr_mem_cnt * sizeof (uint32_t);
 207                   len = (uint32_t *) alloca (lensize);
 208                 }
 209               else if (gr_resp.gr_mem_cnt * sizeof (uint32_t) > lensize)
 210                 len = extend_alloca (len, lensize,
 211                                      gr_resp.gr_mem_cnt * sizeof (uint32_t));
 212
 213               vec[0].iov_base = (void *) len;
 214               vec[0].iov_len = gr_resp.gr_mem_cnt * sizeof (uint32_t);
 215               vec[1].iov_base = resultbuf->gr_name;
 216               vec[1].iov_len = gr_resp.gr_name_len + gr_resp.gr_passwd_len;
 217               total_len = vec[0].iov_len + vec[1].iov_len;
 218
 219               /* Get this data.  */
 220               size_t n = __readvall (sock, vec, 2);
 221               if (__builtin_expect (n != total_len, 0))
 222                 goto out_close;
 223             }
 224         }
 225       else
 226         /* We already have the data.  Just copy the group name and
 227            password.  */
 228         memcpy (resultbuf->gr_name, gr_name,
 229                 gr_resp.gr_name_len + gr_resp.gr_passwd_len);
 230
 231       /* Clear the terminating entry.  */
 232       resultbuf->gr_mem[gr_resp.gr_mem_cnt] = NULL;
 233
 234       /* Prepare reading the group members.  */
 235       total_len = 0;
 236       for (cnt = 0; cnt < gr_resp.gr_mem_cnt; ++cnt)
 237         {
 238           resultbuf->gr_mem[cnt] = p;
 239           total_len += len[cnt];
 240           p += len[cnt];
 241         }
 242
 243       if (__builtin_expect (gr_name + gr_name_len + total_len > recend, 0))
 244         {
 245           /* len array might contain garbage during nscd GC cycle,
 246              retry rather than fail in that case.  */
 247           if (gr_name != NULL && mapped->head->gc_cycle != gc_cycle)
 248             retval = -2;
 249           goto out_close;
 250         }
 251       if (__builtin_expect (total_len > buflen, 0))
 252         {
 253           /* len array might contain garbage during nscd GC cycle,
 254              retry rather than fail in that case.  */
 255           if (gr_name != NULL && mapped->head->gc_cycle != gc_cycle)
 256             {
 257               retval = -2;
 258               goto out_close;
 259             }
 260           else
 261             goto no_room;
 262         }
 263
 264       retval = 0;
 265
 266       /* If there are no group members TOTAL_LEN is zero.  */
 267       if (gr_name == NULL)
 268         {
 269           if (total_len > 0
 270               && __builtin_expect (__readall (sock, resultbuf->gr_mem[0],
 271                                               total_len) != total_len, 0))
 272             {
 273               /* The `errno' to some value != ERANGE.  */
 274               __set_errno (ENOENT);
 275               retval = ENOENT;
 276             }
 277           else
 278             *result = resultbuf;
 279         }
 280       else
 281         {
 282           /* Copy the group member names.  */
 283           memcpy (resultbuf->gr_mem[0], gr_name + gr_name_len, total_len);
 284
 285           /* Try to detect corrupt databases.  */
 286           if (resultbuf->gr_name[gr_name_len - 1] != '\0'
 287               || resultbuf->gr_passwd[gr_resp.gr_passwd_len - 1] != '\0'
 288               || ({for (cnt = 0; cnt < gr_resp.gr_mem_cnt; ++cnt)
 289                     if (resultbuf->gr_mem[cnt][len[cnt] - 1] != '\0')
 290                       break;
 291                   cnt < gr_resp.gr_mem_cnt; }))
 292             {
 293               /* We cannot use the database.  */
 294               retval = mapped->head->gc_cycle != gc_cycle ? -2 : -1;
 295               goto out_close;
 296             }
 297
 298           *result = resultbuf;
 299         }
 300     }
 301   else
 302     {
 303       /* Set errno to 0 to indicate no error, just no found record.  */
 304       __set_errno (0);
 305       /* Even though we have not found anything, the result is zero.  */
 306       retval = 0;
 307     }
 308
 309  out_close:
 310   if (sock != -1)
 311     close_not_cancel_no_status (sock);
 312  out:
 313   if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
 314     {
 315       /* When we come here this means there has been a GC cycle while we
 316          were looking for the data.  This means the data might have been
 317          inconsistent.  Retry if possible.  */
 318       if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
 319         {
 320           /* nscd is just running gc now.  Disable using the mapping.  */
 321           if (atomic_decrement_val (&mapped->counter) == 0)
 322             __nscd_unmap (mapped);
 323           mapped = NO_MAPPING;
 324         }
 325
 326       if (retval != -1)
 327         goto retry;
 328     }
 329
 330   return retval;
 331 }