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, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <assert.h>
  21 #include <errno.h>
  22 #include <pwd.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
  35 #include "nscd-client.h"
  36 #include "nscd_proto.h"
  37
  38 int __nss_not_use_nscd_passwd;
  39
  40 static int nscd_getpw_r (const char *key, size_t keylen, request_type type,
  41                          struct passwd *resultbuf, char *buffer,
  42                          size_t buflen, struct passwd **result)
  43      internal_function;
  44
  45 int
  46 __nscd_getpwnam_r (const char *name, struct passwd *resultbuf, char *buffer,
  47                    size_t buflen, struct passwd **result)
  48 {
  49   if (name == NULL)
  50     return -1;
  51
  52   return nscd_getpw_r (name, strlen (name) + 1, GETPWBYNAME, resultbuf,
  53                        buffer, buflen, result);
  54 }
  55
  56 int
  57 __nscd_getpwuid_r (uid_t uid, struct passwd *resultbuf, char *buffer,
  58                    size_t buflen, struct passwd **result)
  59 {
  60   char buf[3 * sizeof (uid_t)];
  61   buf[sizeof (buf) - 1] = '\0';
  62   char *cp = _itoa_word (uid, buf + sizeof (buf) - 1, 10, 0);
  63
  64   return nscd_getpw_r (cp, buf + sizeof (buf) - cp, GETPWBYUID, resultbuf,
  65                        buffer, buflen, result);
  66 }
  67
  68
  69 libc_locked_map_ptr (static, map_handle);
  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 (pw_map_free)
  74 {
  75   if (map_handle.mapped != NO_MAPPING)
  76     {
  77       void *p = map_handle.mapped;
  78       map_handle.mapped = NO_MAPPING;
  79       free (p);
  80     }
  81 }
  82
  83
  84 static int
  85 internal_function
  86 nscd_getpw_r (const char *key, size_t keylen, request_type type,
  87               struct passwd *resultbuf, char *buffer, size_t buflen,
  88               struct passwd **result)
  89 {
  90   int gc_cycle;
  91   int nretries = 0;
  92
  93   /* If the mapping is available, try to search there instead of
  94      communicating with the nscd.  */
  95   struct mapped_database *mapped;
  96   mapped = __nscd_get_map_ref (GETFDPW, "passwd", &map_handle, &gc_cycle);
  97
  98  retry:;
  99   const char *pw_name = NULL;
 100   int retval = -1;
 101   const char *recend = (const char *) ~UINTMAX_C (0);
 102   pw_response_header pw_resp;
 103
 104   if (mapped != NO_MAPPING)
 105     {
 106       struct datahead *found = __nscd_cache_search (type, key, keylen, mapped,
 107                                                     sizeof pw_resp);
 108       if (found != NULL)
 109         {
 110           pw_name = (const char *) (&found->data[0].pwdata + 1);
 111           pw_resp = found->data[0].pwdata;
 112           recend = (const char *) found->data + found->recsize;
 113           /* Now check if we can trust pw_resp fields.  If GC is
 114              in progress, it can contain anything.  */
 115           if (mapped->head->gc_cycle != gc_cycle)
 116             {
 117               retval = -2;
 118               goto out;
 119             }
 120         }
 121     }
 122
 123   int sock = -1;
 124   if (pw_name == NULL)
 125     {
 126       sock = __nscd_open_socket (key, keylen, type, &pw_resp,
 127                                  sizeof (pw_resp));
 128       if (sock == -1)
 129         {
 130           __nss_not_use_nscd_passwd = 1;
 131           goto out;
 132         }
 133     }
 134
 135   /* No value found so far.  */
 136   *result = NULL;
 137
 138   if (__builtin_expect (pw_resp.found == -1, 0))
 139     {
 140       /* The daemon does not cache this database.  */
 141       __nss_not_use_nscd_passwd = 1;
 142       goto out_close;
 143     }
 144
 145   if (pw_resp.found == 1)
 146     {
 147       /* Set the information we already have.  */
 148       resultbuf->pw_uid = pw_resp.pw_uid;
 149       resultbuf->pw_gid = pw_resp.pw_gid;
 150
 151       char *p = buffer;
 152       /* get pw_name */
 153       resultbuf->pw_name = p;
 154       p += pw_resp.pw_name_len;
 155       /* get pw_passwd */
 156       resultbuf->pw_passwd = p;
 157       p += pw_resp.pw_passwd_len;
 158       /* get pw_gecos */
 159       resultbuf->pw_gecos = p;
 160       p += pw_resp.pw_gecos_len;
 161       /* get pw_dir */
 162       resultbuf->pw_dir = p;
 163       p += pw_resp.pw_dir_len;
 164       /* get pw_pshell */
 165       resultbuf->pw_shell = p;
 166       p += pw_resp.pw_shell_len;
 167
 168       ssize_t total = p - buffer;
 169       if (__builtin_expect (pw_name + total > recend, 0))
 170         goto out_close;
 171       if (__builtin_expect (buflen < total, 0))
 172         {
 173           __set_errno (ERANGE);
 174           retval = ERANGE;
 175           goto out_close;
 176         }
 177
 178       retval = 0;
 179       if (pw_name == NULL)
 180         {
 181           ssize_t nbytes = __readall (sock, buffer, total);
 182
 183           if (__builtin_expect (nbytes != total, 0))
 184             {
 185               /* The `errno' to some value != ERANGE.  */
 186               __set_errno (ENOENT);
 187               retval = ENOENT;
 188             }
 189           else
 190             *result = resultbuf;
 191         }
 192       else
 193         {
 194           /* Copy the various strings.  */
 195           memcpy (resultbuf->pw_name, pw_name, total);
 196
 197           /* Try to detect corrupt databases.  */
 198           if (resultbuf->pw_name[pw_resp.pw_name_len - 1] != '\0'
 199               || resultbuf->pw_passwd[pw_resp.pw_passwd_len - 1] != '\0'
 200               || resultbuf->pw_gecos[pw_resp.pw_gecos_len - 1] != '\0'
 201               || resultbuf->pw_dir[pw_resp.pw_dir_len - 1] != '\0'
 202               || resultbuf->pw_shell[pw_resp.pw_shell_len - 1] != '\0')
 203             {
 204               /* We cannot use the database.  */
 205               retval = mapped->head->gc_cycle != gc_cycle ? -2 : -1;
 206               goto out_close;
 207             }
 208
 209           *result = resultbuf;
 210         }
 211     }
 212   else
 213     {
 214       /* Set errno to 0 to indicate no error, just no found record.  */
 215       __set_errno (0);
 216       /* Even though we have not found anything, the result is zero.  */
 217       retval = 0;
 218     }
 219
 220  out_close:
 221   if (sock != -1)
 222     close_not_cancel_no_status (sock);
 223  out:
 224   if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
 225     {
 226       /* When we come here this means there has been a GC cycle while we
 227          were looking for the data.  This means the data might have been
 228          inconsistent.  Retry if possible.  */
 229       if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
 230         {
 231           /* nscd is just running gc now.  Disable using the mapping.  */
 232           if (atomic_decrement_val (&mapped->counter) == 0)
 233             __nscd_unmap (mapped);
 234           mapped = NO_MAPPING;
 235         }
 236
 237       if (retval != -1)
 238         goto retry;
 239     }
 240
 241   return retval;
 242 }