LCOV - code coverage report
Current view: top level - builds/gnutls/coverage/gnutls-git/lib/tls13 - anti_replay.c (source / functions) Hit Total Coverage
Test: GnuTLS-3.6.7 Code Coverage Lines: 72 77 93.5 %
Date: 2019-04-24 03:13:53 Functions: 7 7 100.0 %
Legend: Lines: hit not hit | Branches: + taken - not taken # not executed Branches: 21 40 52.5 %

           Branch data     Line data    Source code
       1                 :            : /*
       2                 :            :  * Copyright (C) 2018 Red Hat, Inc.
       3                 :            :  *
       4                 :            :  * Author: Daiki Ueno
       5                 :            :  *
       6                 :            :  * This file is part of GnuTLS.
       7                 :            :  *
       8                 :            :  * The GnuTLS is free software; you can redistribute it and/or
       9                 :            :  * modify it under the terms of the GNU Lesser General Public License
      10                 :            :  * as published by the Free Software Foundation; either version 2.1 of
      11                 :            :  * the License, or (at your option) any later version.
      12                 :            :  *
      13                 :            :  * This library is distributed in the hope that it will be useful, but
      14                 :            :  * WITHOUT ANY WARRANTY; without even the implied warranty of
      15                 :            :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      16                 :            :  * Lesser General Public License for more details.
      17                 :            :  *
      18                 :            :  * You should have received a copy of the GNU Lesser General Public License
      19                 :            :  * along with this program.  If not, see <https://www.gnu.org/licenses/>
      20                 :            :  *
      21                 :            :  */
      22                 :            : 
      23                 :            : #include "gnutls_int.h"
      24                 :            : #include "db.h"
      25                 :            : #include "system.h"
      26                 :            : #include "tls13/anti_replay.h"
      27                 :            : 
      28                 :            : /* The default time window in milliseconds; RFC8446 suggests the order
      29                 :            :  * of ten seconds is sufficient for the clients on the Internet. */
      30                 :            : #define DEFAULT_WINDOW_MS 10000
      31                 :            : 
      32                 :            : struct gnutls_anti_replay_st {
      33                 :            :         uint32_t window;
      34                 :            :         struct timespec start_time;
      35                 :            :         gnutls_db_add_func db_add_func;
      36                 :            :         void *db_ptr;
      37                 :            : };
      38                 :            : 
      39                 :            : /**
      40                 :            :  * gnutls_anti_replay_init:
      41                 :            :  * @anti_replay: is a pointer to #gnutls_anti_replay_t type
      42                 :            :  *
      43                 :            :  * This function will allocate and initialize the @anti_replay context
      44                 :            :  * to be usable for detect replay attacks. The context can then be
      45                 :            :  * attached to a @gnutls_session_t with
      46                 :            :  * gnutls_anti_replay_enable().
      47                 :            :  *
      48                 :            :  * Returns: Zero or a negative error code on error.
      49                 :            :  *
      50                 :            :  * Since: 3.6.5
      51                 :            :  **/
      52                 :            : int
      53                 :          8 : gnutls_anti_replay_init(gnutls_anti_replay_t *anti_replay)
      54                 :            : {
      55                 :          8 :         *anti_replay = gnutls_calloc(1, sizeof(struct gnutls_anti_replay_st));
      56         [ -  + ]:          8 :         if (!*anti_replay)
      57         [ #  # ]:          0 :                 return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);
      58                 :            : 
      59                 :          8 :         (*anti_replay)->window = DEFAULT_WINDOW_MS;
      60                 :            : 
      61                 :          8 :         gnutls_gettime(&(*anti_replay)->start_time);
      62                 :            : 
      63                 :          8 :         return 0;
      64                 :            : }
      65                 :            : 
      66                 :            : /**
      67                 :            :  * gnutls_anti_replay_set_window:
      68                 :            :  * @anti_replay: is a #gnutls_anti_replay_t type.
      69                 :            :  * @window: is the time window recording ClientHello, in milliseconds
      70                 :            :  *
      71                 :            :  * Sets the time window used for ClientHello recording.  In order to
      72                 :            :  * protect against replay attacks, the server records ClientHello
      73                 :            :  * messages within this time period from the last update, and
      74                 :            :  * considers it a replay when a ClientHello outside of the period; if
      75                 :            :  * a ClientHello arrives within this period, the server checks the
      76                 :            :  * database and detects duplicates.
      77                 :            :  *
      78                 :            :  * For the details of the algorithm, see RFC 8446, section 8.2.
      79                 :            :  *
      80                 :            :  * Since: 3.6.5
      81                 :            :  */
      82                 :            : void
      83                 :          3 : gnutls_anti_replay_set_window(gnutls_anti_replay_t anti_replay,
      84                 :            :                               unsigned int window)
      85                 :            : {
      86                 :          3 :         anti_replay->window = window;
      87                 :          3 : }
      88                 :            : 
      89                 :            : /**
      90                 :            :  * gnutls_anti_replay_deinit:
      91                 :            :  * @anti_replay: is a #gnutls_anti_replay type
      92                 :            :  *
      93                 :            :  * This function will deinitialize all resources occupied by the given
      94                 :            :  * anti-replay context.
      95                 :            :  *
      96                 :            :  * Since: 3.6.5
      97                 :            :  **/
      98                 :            : void
      99                 :          6 : gnutls_anti_replay_deinit(gnutls_anti_replay_t anti_replay)
     100                 :            : {
     101                 :          6 :         gnutls_free(anti_replay);
     102                 :          6 : }
     103                 :            : 
     104                 :            : /**
     105                 :            :  * gnutls_anti_replay_enable:
     106                 :            :  * @session: is a #gnutls_session_t type.
     107                 :            :  * @anti_replay: is a #gnutls_anti_replay_t type.
     108                 :            :  *
     109                 :            :  * Request that the server should use anti-replay mechanism.
     110                 :            :  *
     111                 :            :  * Since: 3.6.5
     112                 :            :  **/
     113                 :            : void
     114                 :         13 : gnutls_anti_replay_enable(gnutls_session_t session,
     115                 :            :                           gnutls_anti_replay_t anti_replay)
     116                 :            : {
     117         [ -  + ]:         13 :         if (unlikely(session->security_parameters.entity != GNUTLS_SERVER)) {
     118         [ #  # ]:          0 :                 gnutls_assert();
     119                 :          0 :                 return;
     120                 :            :         }
     121                 :            : 
     122                 :         13 :         session->internals.anti_replay = anti_replay;
     123                 :            : }
     124                 :            : 
     125                 :            : int
     126                 :         12 : _gnutls_anti_replay_check(gnutls_anti_replay_t anti_replay,
     127                 :            :                           uint32_t client_ticket_age,
     128                 :            :                           struct timespec *ticket_creation_time,
     129                 :            :                           gnutls_datum_t *id)
     130                 :            : {
     131                 :         12 :         struct timespec now;
     132                 :         12 :         time_t window;
     133                 :         12 :         uint32_t server_ticket_age, diff;
     134                 :         12 :         gnutls_datum_t key = { NULL, 0 };
     135                 :         12 :         gnutls_datum_t entry = { NULL, 0 };
     136                 :         12 :         unsigned char key_buffer[MAX_HASH_SIZE + 12];
     137                 :         12 :         unsigned char entry_buffer[12]; /* magic + timestamp + expire_time */
     138                 :         12 :         unsigned char *p;
     139                 :         12 :         int ret;
     140                 :            : 
     141         [ -  + ]:         12 :         if (unlikely(id->size > MAX_HASH_SIZE))
     142         [ #  # ]:          0 :                 return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);
     143                 :            : 
     144                 :         12 :         gnutls_gettime(&now);
     145                 :         12 :         server_ticket_age = timespec_sub_ms(&now, ticket_creation_time);
     146                 :            : 
     147                 :            :         /* It shouldn't be possible that the server's view of ticket
     148                 :            :          * age is smaller than the client's view.
     149                 :            :          */
     150         [ +  + ]:         12 :         if (unlikely(server_ticket_age < client_ticket_age))
     151         [ -  + ]:          1 :                 return gnutls_assert_val(GNUTLS_E_ILLEGAL_PARAMETER);
     152                 :            : 
     153                 :            :         /* If ticket is created before recording has started, discard
     154                 :            :          * reject early data.
     155                 :            :          */
     156         [ +  + ]:         11 :         if (_gnutls_timespec_cmp(ticket_creation_time,
     157                 :            :                                  &anti_replay->start_time) < 0) {
     158         [ -  + ]:          1 :                 _gnutls_handshake_log("anti_replay: ticket is created before recording has started\n");
     159         [ -  + ]:          1 :                 return gnutls_assert_val(GNUTLS_E_EARLY_DATA_REJECTED);
     160                 :            :         }
     161                 :            : 
     162                 :            :         /* If certain amount of time (window) has elapsed, rollover
     163                 :            :          * the recording.
     164                 :            :          */
     165                 :         10 :         diff = timespec_sub_ms(&now, &anti_replay->start_time);
     166         [ +  + ]:         10 :         if (diff > anti_replay->window)
     167                 :          2 :                 gnutls_gettime(&anti_replay->start_time);
     168                 :            : 
     169                 :            :         /* If expected_arrival_time is out of window, reject early
     170                 :            :          * data.
     171                 :            :          */
     172         [ +  + ]:         10 :         if (server_ticket_age - client_ticket_age > anti_replay->window) {
     173         [ -  + ]:          1 :                 _gnutls_handshake_log("anti_replay: server ticket age: %u, client ticket age: %u\n",
     174                 :            :                                       server_ticket_age,
     175                 :            :                                       client_ticket_age);
     176         [ -  + ]:          1 :                 return gnutls_assert_val(GNUTLS_E_EARLY_DATA_REJECTED);
     177                 :            :         }
     178                 :            : 
     179                 :            :         /* Check if the ClientHello is stored in the database.
     180                 :            :          */
     181         [ -  + ]:          9 :         if (!anti_replay->db_add_func)
     182         [ #  # ]:          0 :                 return gnutls_assert_val(GNUTLS_E_EARLY_DATA_REJECTED);
     183                 :            : 
     184                 :            :         /* Create a key for database lookup, prefixing window start
     185                 :            :          * time to ID.  Note that this shouldn't clash with session ID
     186                 :            :          * used in TLS 1.2, because such IDs are 32 octets, while here
     187                 :            :          * the key becomes 44+ octets.
     188                 :            :          */
     189                 :          9 :         p = key_buffer;
     190                 :          9 :         _gnutls_write_uint32((uint64_t) anti_replay->start_time.tv_sec >> 32, p);
     191                 :          9 :         p += 4;
     192                 :          9 :         _gnutls_write_uint32(anti_replay->start_time.tv_sec & 0xFFFFFFFF, p);
     193                 :          9 :         p += 4;
     194                 :          9 :         _gnutls_write_uint32(anti_replay->start_time.tv_nsec, p);
     195                 :          9 :         p += 4;
     196                 :          9 :         memcpy(p, id->data, id->size);
     197                 :          9 :         p += id->size;
     198                 :          9 :         key.data = key_buffer;
     199                 :          9 :         key.size = p - key_buffer;
     200                 :            : 
     201                 :            :         /* Create an entry to be stored on database if the lookup
     202                 :            :          * failed.  This is formatted so that
     203                 :            :          * gnutls_db_check_entry_expire_time() work.
     204                 :            :          */
     205                 :          9 :         p = entry_buffer;
     206                 :          9 :         _gnutls_write_uint32(PACKED_SESSION_MAGIC, p);
     207                 :          9 :         p += 4;
     208                 :          9 :         _gnutls_write_uint32(now.tv_sec, p);
     209                 :          9 :         p += 4;
     210                 :          9 :         window = anti_replay->window / 1000;
     211                 :          9 :         _gnutls_write_uint32(window, p);
     212                 :          9 :         p += 4;
     213                 :          9 :         entry.data = entry_buffer;
     214                 :          9 :         entry.size = p - entry_buffer;
     215                 :            : 
     216                 :         27 :         ret = anti_replay->db_add_func(anti_replay->db_ptr,
     217                 :          9 :                                        (uint64_t)now.tv_sec+(uint64_t)window, &key, &entry);
     218         [ +  + ]:          9 :         if (ret < 0) {
     219         [ -  + ]:          3 :                 _gnutls_handshake_log("anti_replay: duplicate ClientHello found\n");
     220         [ -  + ]:          3 :                 return gnutls_assert_val(GNUTLS_E_EARLY_DATA_REJECTED);
     221                 :            :         }
     222                 :            : 
     223                 :            :         return 0;
     224                 :            : }
     225                 :            : 
     226                 :            : /**
     227                 :            :  * gnutls_anti_replay_set_ptr:
     228                 :            :  * @anti_replay: is a #gnutls_anti_replay_t type.
     229                 :            :  * @ptr: is the pointer
     230                 :            :  *
     231                 :            :  * Sets the pointer that will be provided to db add function
     232                 :            :  * as the first argument.
     233                 :            :  **/
     234                 :          8 : void gnutls_anti_replay_set_ptr(gnutls_anti_replay_t anti_replay, void *ptr)
     235                 :            : {
     236                 :          8 :         anti_replay->db_ptr = ptr;
     237                 :          8 : }
     238                 :            : 
     239                 :            : /**
     240                 :            :  * gnutls_anti_replay_set_add_function:
     241                 :            :  * @anti_replay: is a #gnutls_anti_replay_t type.
     242                 :            :  * @add_func: is the function.
     243                 :            :  *
     244                 :            :  * Sets the function that will be used to store an entry if it is not
     245                 :            :  * already present in the resumed sessions database.  This function returns 0
     246                 :            :  * if the entry is successfully stored, and a negative error code
     247                 :            :  * otherwise.  In particular, if the entry is found in the database,
     248                 :            :  * it returns %GNUTLS_E_DB_ENTRY_EXISTS.
     249                 :            :  *
     250                 :            :  * The arguments to the @add_func are:
     251                 :            :  *  - %ptr: the pointer set with gnutls_anti_replay_set_ptr()
     252                 :            :  *  - %exp_time: the expiration time of the entry
     253                 :            :  *  - %key: a pointer to the key
     254                 :            :  *  - %data: a pointer to data to store
     255                 :            :  *
     256                 :            :  * The data set by this function can be examined using
     257                 :            :  * gnutls_db_check_entry_expire_time() and gnutls_db_check_entry_time().
     258                 :            :  *
     259                 :            :  * Since: 3.6.5
     260                 :            :  **/
     261                 :            : void
     262                 :          8 : gnutls_anti_replay_set_add_function(gnutls_anti_replay_t anti_replay,
     263                 :            :                                     gnutls_db_add_func add_func)
     264                 :            : {
     265                 :          8 :         anti_replay->db_add_func = add_func;
     266                 :          8 : }

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