nscd/nscd_getpw_r.c

   1 /* Copyright (C) 1998, 1999, 2003, 2004, 2005, 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 <assert.h>
  22 #include <errno.h>
  23 #include <pwd.h>
  24 #include <stdint.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <unistd.h>
  29 #include <sys/mman.h>
  30 #include <sys/socket.h>
  31 #include <sys/uio.h>
  32 #include <sys/un.h>
  33 #include <not-cancel.h>
  34 #include <stdio-common/_itoa.h>
  35
  36 #include "nscd-client.h"
  37 #include "nscd_proto.h"
  38
  39 int __nss_not_use_nscd_passwd;
  40
  41 static int nscd_getpw_r (const char *key, size_t keylen, request_type type,
  42                          struct passwd *resultbuf, char *buffer,
  43                          size_t buflen, struct passwd **result)
  44      internal_function;
  45
  46 int
  47 __nscd_getpwnam_r (const char *name, struct passwd *resultbuf, char *buffer,
  48                    size_t buflen, struct passwd **result)
  49 {
  50   if (name == NULL)
  51     return -1;
  52
  53   return nscd_getpw_r (name, strlen (name) + 1, GETPWBYNAME, resultbuf,
  54                        buffer, buflen, result);
  55 }
  56
  57 int
  58 __nscd_getpwuid_r (uid_t uid, struct passwd *resultbuf, char *buffer,
  59                    size_t buflen, struct passwd **result)
  60 {
  61   char buf[3 * sizeof (uid_t)];
  62   buf[sizeof (buf) - 1] = '\0';
  63   char *cp = _itoa_word (uid, buf + sizeof (buf) - 1, 10, 0);
  64
  65   return nscd_getpw_r (cp, buf + sizeof (buf) - cp, GETPWBYUID, resultbuf,
  66                        buffer, buflen, result);
  67 }
  68
  69
  70 libc_locked_map_ptr (static, map_handle);
  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 (pw_map_free)
  75 {
  76   if (map_handle.mapped != NO_MAPPING)
  77     {
  78       void *p = map_handle.mapped;
  79       map_handle.mapped = NO_MAPPING;
  80       free (p);
  81     }
  82 }
  83
  84
  85 static int
  86 internal_function
  87 nscd_getpw_r (const char *key, size_t keylen, request_type type,
  88               struct passwd *resultbuf, char *buffer, size_t buflen,
  89               struct passwd **result)
  90 {
  91   int gc_cycle;
  92   int nretries = 0;
  93
  94   /* If the mapping is available, try to search there instead of
  95      communicating with the nscd.  */
  96   struct mapped_database *mapped;
  97   mapped = __nscd_get_map_ref (GETFDPW, "passwd", &map_handle, &gc_cycle);
  98
  99  retry:;
 100   const char *pw_name = NULL;
 101   int retval = -1;
 102   const char *recend = (const char *) ~UINTMAX_C (0);
 103   pw_response_header pw_resp;
 104
 105   if (mapped != NO_MAPPING)
 106     {
 107       struct datahead *found = __nscd_cache_search (type, key, keylen, mapped,
 108                                                     sizeof pw_resp);
 109       if (found != NULL)
 110         {
 111           pw_name = (const char *) (&found->data[0].pwdata + 1);
 112           pw_resp = found->data[0].pwdata;
 113           recend = (const char *) found->data + found->recsize;
 114           /* Now check if we can trust pw_resp fields.  If GC is
 115              in progress, it can contain anything.  */
 116           if (mapped->head->gc_cycle != gc_cycle)
 117             {
 118               retval = -2;
 119               goto out;
 120             }
 121         }
 122     }
 123
 124   int sock = -1;
 125   if (pw_name == NULL)
 126     {
 127       sock = __nscd_open_socket (key, keylen, type, &pw_resp,
 128                                  sizeof (pw_resp));
 129       if (sock == -1)
 130         {
 131           __nss_not_use_nscd_passwd = 1;
 132           goto out;
 133         }
 134     }
 135
 136   /* No value found so far.  */
 137   *result = NULL;
 138
 139   if (__builtin_expect (pw_resp.found == -1, 0))
 140     {
 141       /* The daemon does not cache this database.  */
 142       __nss_not_use_nscd_passwd = 1;
 143       goto out_close;
 144     }
 145
 146   if (pw_resp.found == 1)
 147     {
 148       /* Set the information we already have.  */
 149       resultbuf->pw_uid = pw_resp.pw_uid;
 150       resultbuf->pw_gid = pw_resp.pw_gid;
 151
 152       char *p = buffer;
 153       /* get pw_name */
 154       resultbuf->pw_name = p;
 155       p += pw_resp.pw_name_len;
 156       /* get pw_passwd */
 157       resultbuf->pw_passwd = p;
 158       p += pw_resp.pw_passwd_len;
 159       /* get pw_gecos */
 160       resultbuf->pw_gecos = p;
 161       p += pw_resp.pw_gecos_len;
 162       /* get pw_dir */
 163       resultbuf->pw_dir = p;
 164       p += pw_resp.pw_dir_len;
 165       /* get pw_pshell */
 166       resultbuf->pw_shell = p;
 167       p += pw_resp.pw_shell_len;
 168
 169       ssize_t total = p - buffer;
 170       if (__builtin_expect (pw_name + total > recend, 0))
 171         goto out_close;
 172       if (__builtin_expect (buflen < total, 0))
 173         {
 174           __set_errno (ERANGE);
 175           retval = ERANGE;
 176           goto out_close;
 177         }
 178
 179       retval = 0;
 180       if (pw_name == NULL)
 181         {
 182           ssize_t nbytes = __readall (sock, buffer, total);
 183
 184           if (__builtin_expect (nbytes != total, 0))
 185             {
 186               /* The `errno' to some value != ERANGE.  */
 187               __set_errno (ENOENT);
 188               retval = ENOENT;
 189             }
 190           else
 191             *result = resultbuf;
 192         }
 193       else
 194         {
 195           /* Copy the various strings.  */
 196           memcpy (resultbuf->pw_name, pw_name, total);
 197
 198           /* Try to detect corrupt databases.  */
 199           if (resultbuf->pw_name[pw_resp.pw_name_len - 1] != '\0'
 200               || resultbuf->pw_passwd[pw_resp.pw_passwd_len - 1] != '\0'
 201               || resultbuf->pw_gecos[pw_resp.pw_gecos_len - 1] != '\0'
 202               || resultbuf->pw_dir[pw_resp.pw_dir_len - 1] != '\0'
 203               || resultbuf->pw_shell[pw_resp.pw_shell_len - 1] != '\0')
 204             {
 205               /* We cannot use the database.  */
 206               retval = mapped->head->gc_cycle != gc_cycle ? -2 : -1;
 207               goto out_close;
 208             }
 209
 210           *result = resultbuf;
 211         }
 212     }
 213   else
 214     {
 215       /* Set errno to 0 to indicate no error, just no found record.  */
 216       __set_errno (0);
 217       /* Even though we have not found anything, the result is zero.  */
 218       retval = 0;
 219     }
 220
 221  out_close:
 222   if (sock != -1)
 223     close_not_cancel_no_status (sock);
 224  out:
 225   if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
 226     {
 227       /* When we come here this means there has been a GC cycle while we
 228          were looking for the data.  This means the data might have been
 229          inconsistent.  Retry if possible.  */
 230       if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
 231         {
 232           /* nscd is just running gc now.  Disable using the mapping.  */
 233           if (atomic_decrement_val (&mapped->counter) == 0)
 234             __nscd_unmap (mapped);
 235           mapped = NO_MAPPING;
 236         }
 237
 238       if (retval != -1)
 239         goto retry;
 240     }
 241
 242   return retval;
 243 }