nscd/nscd_getpw_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 <assert.h>
  20 #include <errno.h>
  21 #include <pwd.h>
  22 #include <stdint.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <unistd.h>
  27 #include <sys/mman.h>
  28 #include <sys/socket.h>
  29 #include <sys/uio.h>
  30 #include <sys/un.h>
  31 #include <not-cancel.h>
  32 #include <_itoa.h>
  33
  34 #include "nscd-client.h"
  35 #include "nscd_proto.h"
  36
  37 int __nss_not_use_nscd_passwd;
  38
  39 static int nscd_getpw_r (const char *key, size_t keylen, request_type type,
  40                          struct passwd *resultbuf, char *buffer,
  41                          size_t buflen, struct passwd **result)
  42      internal_function;
  43
  44 int
  45 __nscd_getpwnam_r (const char *name, struct passwd *resultbuf, char *buffer,
  46                    size_t buflen, struct passwd **result)
  47 {
  48   if (name == NULL)
  49     return -1;
  50
  51   return nscd_getpw_r (name, strlen (name) + 1, GETPWBYNAME, resultbuf,
  52                        buffer, buflen, result);
  53 }
  54
  55 int
  56 __nscd_getpwuid_r (uid_t uid, struct passwd *resultbuf, char *buffer,
  57                    size_t buflen, struct passwd **result)
  58 {
  59   char buf[3 * sizeof (uid_t)];
  60   buf[sizeof (buf) - 1] = '\0';
  61   char *cp = _itoa_word (uid, buf + sizeof (buf) - 1, 10, 0);
  62
  63   return nscd_getpw_r (cp, buf + sizeof (buf) - cp, GETPWBYUID, resultbuf,
  64                        buffer, buflen, result);
  65 }
  66
  67
  68 libc_locked_map_ptr (static, map_handle);
  69 /* Note that we only free the structure if necessary.  The memory
  70    mapping is not removed since it is not visible to the malloc
  71    handling.  */
  72 libc_freeres_fn (pw_map_free)
  73 {
  74   if (map_handle.mapped != NO_MAPPING)
  75     {
  76       void *p = map_handle.mapped;
  77       map_handle.mapped = NO_MAPPING;
  78       free (p);
  79     }
  80 }
  81
  82
  83 static int
  84 internal_function
  85 nscd_getpw_r (const char *key, size_t keylen, request_type type,
  86               struct passwd *resultbuf, char *buffer, size_t buflen,
  87               struct passwd **result)
  88 {
  89   int gc_cycle;
  90   int nretries = 0;
  91
  92   /* If the mapping is available, try to search there instead of
  93      communicating with the nscd.  */
  94   struct mapped_database *mapped;
  95   mapped = __nscd_get_map_ref (GETFDPW, "passwd", &map_handle, &gc_cycle);
  96
  97  retry:;
  98   const char *pw_name = NULL;
  99   int retval = -1;
 100   const char *recend = (const char *) ~UINTMAX_C (0);
 101   pw_response_header pw_resp;
 102
 103   if (mapped != NO_MAPPING)
 104     {
 105       struct datahead *found = __nscd_cache_search (type, key, keylen, mapped,
 106                                                     sizeof pw_resp);
 107       if (found != NULL)
 108         {
 109           pw_name = (const char *) (&found->data[0].pwdata + 1);
 110           pw_resp = found->data[0].pwdata;
 111           recend = (const char *) found->data + found->recsize;
 112           /* Now check if we can trust pw_resp fields.  If GC is
 113              in progress, it can contain anything.  */
 114           if (mapped->head->gc_cycle != gc_cycle)
 115             {
 116               retval = -2;
 117               goto out;
 118             }
 119         }
 120     }
 121
 122   int sock = -1;
 123   if (pw_name == NULL)
 124     {
 125       sock = __nscd_open_socket (key, keylen, type, &pw_resp,
 126                                  sizeof (pw_resp));
 127       if (sock == -1)
 128         {
 129           __nss_not_use_nscd_passwd = 1;
 130           goto out;
 131         }
 132     }
 133
 134   /* No value found so far.  */
 135   *result = NULL;
 136
 137   if (__glibc_unlikely (pw_resp.found == -1))
 138     {
 139       /* The daemon does not cache this database.  */
 140       __nss_not_use_nscd_passwd = 1;
 141       goto out_close;
 142     }
 143
 144   if (pw_resp.found == 1)
 145     {
 146       /* Set the information we already have.  */
 147       resultbuf->pw_uid = pw_resp.pw_uid;
 148       resultbuf->pw_gid = pw_resp.pw_gid;
 149
 150       char *p = buffer;
 151       /* get pw_name */
 152       resultbuf->pw_name = p;
 153       p += pw_resp.pw_name_len;
 154       /* get pw_passwd */
 155       resultbuf->pw_passwd = p;
 156       p += pw_resp.pw_passwd_len;
 157       /* get pw_gecos */
 158       resultbuf->pw_gecos = p;
 159       p += pw_resp.pw_gecos_len;
 160       /* get pw_dir */
 161       resultbuf->pw_dir = p;
 162       p += pw_resp.pw_dir_len;
 163       /* get pw_pshell */
 164       resultbuf->pw_shell = p;
 165       p += pw_resp.pw_shell_len;
 166
 167       ssize_t total = p - buffer;
 168       if (__glibc_unlikely (pw_name + total > recend))
 169         goto out_close;
 170       if (__glibc_unlikely (buflen < total))
 171         {
 172           __set_errno (ERANGE);
 173           retval = ERANGE;
 174           goto out_close;
 175         }
 176
 177       retval = 0;
 178       if (pw_name == NULL)
 179         {
 180           ssize_t nbytes = __readall (sock, buffer, total);
 181
 182           if (__glibc_unlikely (nbytes != total))
 183             {
 184               /* The `errno' to some value != ERANGE.  */
 185               __set_errno (ENOENT);
 186               retval = ENOENT;
 187             }
 188           else
 189             *result = resultbuf;
 190         }
 191       else
 192         {
 193           /* Copy the various strings.  */
 194           memcpy (resultbuf->pw_name, pw_name, total);
 195
 196           /* Try to detect corrupt databases.  */
 197           if (resultbuf->pw_name[pw_resp.pw_name_len - 1] != '\0'
 198               || resultbuf->pw_passwd[pw_resp.pw_passwd_len - 1] != '\0'
 199               || resultbuf->pw_gecos[pw_resp.pw_gecos_len - 1] != '\0'
 200               || resultbuf->pw_dir[pw_resp.pw_dir_len - 1] != '\0'
 201               || resultbuf->pw_shell[pw_resp.pw_shell_len - 1] != '\0')
 202             {
 203               /* We cannot use the database.  */
 204               retval = mapped->head->gc_cycle != gc_cycle ? -2 : -1;
 205               goto out_close;
 206             }
 207
 208           *result = resultbuf;
 209         }
 210     }
 211   else
 212     {
 213       /* Set errno to 0 to indicate no error, just no found record.  */
 214       __set_errno (0);
 215       /* Even though we have not found anything, the result is zero.  */
 216       retval = 0;
 217     }
 218
 219  out_close:
 220   if (sock != -1)
 221     close_not_cancel_no_status (sock);
 222  out:
 223   if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
 224     {
 225       /* When we come here this means there has been a GC cycle while we
 226          were looking for the data.  This means the data might have been
 227          inconsistent.  Retry if possible.  */
 228       if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
 229         {
 230           /* nscd is just running gc now.  Disable using the mapping.  */
 231           if (atomic_decrement_val (&mapped->counter) == 0)
 232             __nscd_unmap (mapped);
 233           mapped = NO_MAPPING;
 234         }
 235
 236       if (retval != -1)
 237         goto retry;
 238     }
 239
 240   return retval;
 241 }