ui/ssl_key_export.c

   1 /* export_sslkeys.c
   2  *
   3  * Export SSL Session Keys dialog
   4  * by Sake Blok <sake@euronet.nl> (20110526)
   5  *
   6  * Wireshark - Network traffic analyzer
   7  * By Gerald Combs <gerald@wireshark.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  10  * SPDX-License-Identifier: GPL-2.0-or-later
  11  */
  12
  13 #include "config.h"
  14
  15 #include <glib.h>
  16
  17 #include <epan/address.h>
  18 #include <epan/dissectors/packet-tls-utils.h>
  19
  20 #include <wiretap/secrets-types.h>
  21
  22 #include "ui/ssl_key_export.h"
  23
  24 int
  25 ssl_session_key_count(void)
  26 {
  27     int count = 0;
  28     ssl_master_key_map_t *mk_map = tls_get_master_key_map(false);
  29     if (!mk_map || !mk_map->used_crandom)
  30         return count;
  31
  32     GHashTableIter iter;
  33     void *key;
  34
  35     g_hash_table_iter_init(&iter, mk_map->used_crandom);
  36     while (g_hash_table_iter_next(&iter, &key, NULL)) {
  37         if (g_hash_table_contains(mk_map->crandom, key)) {
  38             count++;
  39         }
  40         if (g_hash_table_contains(mk_map->tls13_client_early, key)) {
  41             count++;
  42         }
  43         if (g_hash_table_contains(mk_map->tls13_client_handshake, key)) {
  44             count++;
  45         }
  46         if (g_hash_table_contains(mk_map->tls13_server_handshake, key)) {
  47             count++;
  48         }
  49         if (g_hash_table_contains(mk_map->tls13_client_appdata, key)) {
  50             count++;
  51         }
  52         if (g_hash_table_contains(mk_map->tls13_server_appdata, key)) {
  53             count++;
  54         }
  55     }
  56     return count;
  57 }
  58
  59 static void
  60 tls_export_client_randoms_func(void *key, void *value, void *user_data, const char* label)
  61 {
  62     unsigned i;
  63     StringInfo *client_random = (StringInfo *)key;
  64     StringInfo *master_secret = (StringInfo *)value;
  65     GString *keylist = (GString *)user_data;
  66
  67     g_string_append(keylist, label);
  68
  69     for (i = 0; i < client_random->data_len; i++) {
  70         g_string_append_printf(keylist, "%.2x", client_random->data[i]);
  71     }
  72
  73     g_string_append_c(keylist, ' ');
  74
  75     for (i = 0; i < master_secret->data_len; i++) {
  76         g_string_append_printf(keylist, "%.2x", master_secret->data[i]);
  77     }
  78
  79     g_string_append_c(keylist, '\n');
  80 }
  81
  82 char*
  83 ssl_export_sessions(size_t *length)
  84 {
  85     /* Output format is:
  86      * "CLIENT_RANDOM zzzz yyyy\n"
  87      * Where zzzz is the client random (always 64 chars)
  88      * Where yyyy is same as above
  89      * So length will always be 13+1+64+1+96+2 = 177 chars
  90      *
  91      * Wireshark can read CLIENT_RANDOM since v1.8.0.
  92      * Both values are exported in case you use the Session-ID for resuming a
  93      * session in a different capture.
  94      *
  95      * TLS 1.3 derived secrets are similar to the CLIENT_RANDOM master secret
  96      * export, but with a (longer) label indicating the type of derived secret
  97      * to which the client random maps, e.g.
  98      * "CLIENT_HANDSHAKE_TRAFFIC_SECRET zzzz yyyy\n"
  99      *
 100      * The TLS 1.3 values are obtained from an existing key log, but exporting
 101      * them is useful in order to filter actually used secrets or add a DSB.
 102      */
 103     ssl_master_key_map_t *mk_map = tls_get_master_key_map(false);
 104
 105     if (!mk_map) {
 106         *length = 0;
 107         return g_strdup("");
 108     }
 109
 110     size_t len = 177 * (size_t)ssl_session_key_count();
 111     GString *keylist = g_string_sized_new(len);
 112
 113     GHashTableIter iter;
 114     void *key, *value;
 115
 116     g_hash_table_iter_init(&iter, mk_map->used_crandom);
 117     while (g_hash_table_iter_next(&iter, &key, NULL)) {
 118         if ((value = g_hash_table_lookup(mk_map->crandom, key))) {
 119             tls_export_client_randoms_func(key, value, (void *)keylist, "CLIENT_RANDOM ");
 120         }
 121         if ((value = g_hash_table_lookup(mk_map->tls13_client_early, key))) {
 122             tls_export_client_randoms_func(key, value, (void *)keylist, "CLIENT_EARLY_TRAFFIC_SECRET ");
 123         }
 124         if ((value = g_hash_table_lookup(mk_map->tls13_client_handshake, key))) {
 125             tls_export_client_randoms_func(key, value, (void *)keylist, "CLIENT_HANDSHAKE_TRAFFIC_SECRET ");
 126         }
 127         if ((value = g_hash_table_lookup(mk_map->tls13_server_handshake, key))) {
 128             tls_export_client_randoms_func(key, value, (void *)keylist, "SERVER_HANDSHAKE_TRAFFIC_SECRET ");
 129         }
 130         if ((value = g_hash_table_lookup(mk_map->tls13_server_appdata, key))) {
 131             tls_export_client_randoms_func(key, value, (void *)keylist, "SERVER_TRAFFIC_SECRET_0 ");
 132         }
 133         if ((value = g_hash_table_lookup(mk_map->tls13_client_appdata, key))) {
 134             tls_export_client_randoms_func(key, value, (void *)keylist, "CLIENT_TRAFFIC_SECRET_0 ");
 135         }
 136         if ((value = g_hash_table_lookup(mk_map->tls13_early_exporter, key))) {
 137             tls_export_client_randoms_func(key, value, (void *)keylist, "EARLY_EXPORTER_SECRET ");
 138         }
 139         if ((value = g_hash_table_lookup(mk_map->tls13_exporter, key))) {
 140             tls_export_client_randoms_func(key, value, (void *)keylist, "EXPORTER_SECRET ");
 141         }
 142     }
 143
 144     *length = keylist->len;
 145     return g_string_free(keylist, FALSE);
 146 }
 147
 148 void
 149 tls_export_dsb(capture_file *cf)
 150 {
 151     wtap_block_t block;
 152     wtapng_dsb_mandatory_t *dsb;
 153     size_t secrets_len;
 154     char* secrets = ssl_export_sessions(&secrets_len);
 155
 156     block = wtap_block_create(WTAP_BLOCK_DECRYPTION_SECRETS);
 157     dsb = (wtapng_dsb_mandatory_t *)wtap_block_get_mandatory_data(block);
 158
 159     dsb->secrets_type = SECRETS_TYPE_TLS;
 160     dsb->secrets_data = g_memdup2(secrets, secrets_len);
 161     dsb->secrets_len = (unsigned)secrets_len;
 162
 163     /* XXX - support replacing the DSB of the same type instead of adding? */
 164     wtap_file_add_decryption_secrets(cf->provider.wth, block);
 165     /* Mark the file as having unsaved changes */
 166     cf->unsaved_changes = true;
 167
 168     return;
 169 }