#include <epan/expert.h>
#include <epan/prefs.h>
#include <epan/proto_data.h>
+#include <epan/uat.h>
+#include <wsutil/wsgcrypt.h>
+#include <wsutil/curve25519.h>
+
+#if GCRYPT_VERSION_NUMBER >= 0x010800 /* 1.8.0 */
+/* Decryption requires Curve25519, ChaCha20-Poly1305 (1.7) and Blake2s (1.8). */
+#define WG_DECRYPTION_SUPPORTED
+#endif
void proto_reg_handoff_wg(void);
void proto_register_wg(void);
static int hf_wg_stream = -1;
static int hf_wg_response_in = -1;
static int hf_wg_response_to = -1;
+static int hf_wg_receiver_pubkey = -1;
+static int hf_wg_receiver_pubkey_known_privkey = -1;
static gint ett_wg = -1;
+static gint ett_key_info = -1;
static expert_field ei_wg_bad_packet_length = EI_INIT;
static expert_field ei_wg_keepalive = EI_INIT;
{ 0x00, NULL }
};
+#ifdef WG_DECRYPTION_SUPPORTED
+/* Decryption types. {{{ */
+/*
+ * Most operations operate on 32 byte units (keys and hash output).
+ */
+typedef struct {
+#define WG_KEY_LEN 32
+ guchar data[WG_KEY_LEN];
+} wg_qqword;
+
+/*
+ * Static key with the MAC1 key pre-computed and an optional private key.
+ */
+typedef struct wg_skey {
+ wg_qqword pub_key;
+ wg_qqword mac1_key;
+ wg_qqword priv_key; /* Optional, set to all zeroes if missing. */
+} wg_skey_t;
+
+/*
+ * Set of (long-term) static keys (for guessing the peer based on MAC1).
+ * Maps the public key to the "wg_skey_t" structure.
+ * Keys are populated from the UAT and key log file.
+ */
+static GHashTable *wg_static_keys;
+
+/* UAT adapter for populating wg_static_keys. */
+enum { WG_KEY_UAT_PUBLIC, WG_KEY_UAT_PRIVATE };
+static const value_string wg_key_uat_type_vals[] = {
+ { WG_KEY_UAT_PUBLIC, "Public" },
+ { WG_KEY_UAT_PRIVATE, "Private" },
+ { 0, NULL }
+};
+
+typedef struct {
+ guint key_type; /* See "wg_key_uat_type_vals". */
+ char *key;
+} wg_key_uat_record_t;
+
+static wg_key_uat_record_t *wg_key_records;
+static guint num_wg_key_records;
+/* Decryption types. }}} */
+#endif /* WG_DECRYPTION_SUPPORTED */
+
/*
* Information required to process and link messages as required on the first
* sequential pass. After that it can be erased.
static guint32 wg_session_count;
+#ifdef WG_DECRYPTION_SUPPORTED
+/* Key conversion routines. {{{ */
+/* Import external random data as private key. */
+static void
+set_private_key(wg_qqword *privkey, const wg_qqword *inkey)
+{
+ // The 254th bit of a Curve25519 secret will always be set in calculations,
+ // use this property to recognize whether a private key is set.
+ *privkey = *inkey;
+ privkey->data[31] |= 64;
+}
+
+/* Whether a private key is initialized (see set_private_key). */
+static inline gboolean
+has_private_key(const wg_qqword *secret)
+{
+ return !!(secret->data[31] & 64);
+}
+
+/**
+ * Compute the Curve25519 public key from a private key.
+ */
+static void
+priv_to_pub(wg_qqword *pub, const wg_qqword *priv)
+{
+ int r = crypto_scalarmult_curve25519_base(pub->data, priv->data);
+ /* The computation should always be possible. */
+ DISSECTOR_ASSERT(r == 0);
+}
+
+/*
+ * Returns the string representation (base64) of a public key.
+ * The returned value is allocated with wmem_packet_scope.
+ */
+static const char *
+pubkey_to_string(const wg_qqword *pubkey)
+{
+ gchar *str = g_base64_encode(pubkey->data, WG_KEY_LEN);
+ gchar *ret = wmem_strdup(wmem_packet_scope(), str);
+ g_free(str);
+ return ret;
+}
+
+static gboolean
+decode_base64_key(wg_qqword *out, const char *str)
+{
+ gsize out_len;
+ gchar tmp[45];
+
+ if (strlen(str) + 1 != sizeof(tmp)) {
+ return FALSE;
+ }
+ memcpy(tmp, str, sizeof(tmp));
+ g_base64_decode_inplace(tmp, &out_len);
+ if (out_len != WG_KEY_LEN) {
+ return FALSE;
+ }
+ memcpy(out->data, tmp, WG_KEY_LEN);
+ return TRUE;
+}
+/* Key conversion routines. }}} */
+
+static gboolean
+wg_pubkey_equal(gconstpointer v1, gconstpointer v2)
+{
+ const wg_qqword *pubkey1 = (const wg_qqword *)v1;
+ const wg_qqword *pubkey2 = (const wg_qqword *)v2;
+ return !memcmp(pubkey1->data, pubkey2->data, WG_KEY_LEN);
+}
+
+
+/* Protocol-specific crypto routines. {{{ */
+/**
+ * Computes MAC1. Caller must ensure that GCRY_MD_BLAKE2S_256 is available.
+ */
+static void
+wg_mac1_key(const wg_qqword *static_public, wg_qqword *mac_key_out)
+{
+ gcry_md_hd_t hd;
+ if (gcry_md_open(&hd, GCRY_MD_BLAKE2S_256, 0) == 0) {
+ const char wg_label_mac1[] = "mac1----";
+ gcry_md_write(hd, wg_label_mac1, strlen(wg_label_mac1));
+ gcry_md_write(hd, static_public->data, sizeof(wg_qqword));
+ memcpy(mac_key_out->data, gcry_md_read(hd, 0), sizeof(wg_qqword));
+ gcry_md_close(hd);
+ return;
+ }
+ // caller should have checked this.
+ DISSECTOR_ASSERT_NOT_REACHED();
+}
+
+/*
+ * Verify that MAC(mac_key, data) matches "mac_output".
+ */
+static gboolean
+wg_mac_verify(const wg_qqword *mac_key,
+ const guchar *data, guint data_len, const guint8 mac_output[16])
+{
+ gboolean ok = FALSE;
+ gcry_md_hd_t hd;
+ if (gcry_md_open(&hd, GCRY_MD_BLAKE2S_128, 0) == 0) {
+ gcry_error_t r;
+ // not documented by Libgcrypt, but required for keyed blake2s
+ r = gcry_md_setkey(hd, mac_key->data, WG_KEY_LEN);
+ DISSECTOR_ASSERT(r == 0);
+ gcry_md_write(hd, data, data_len);
+ ok = memcmp(mac_output, gcry_md_read(hd, 0), 16) == 0;
+ gcry_md_close(hd);
+ } else {
+ // caller should have checked this.
+ DISSECTOR_ASSERT_NOT_REACHED();
+ }
+ return ok;
+}
+/* Protocol-specific crypto routines. }}} */
+
+/*
+ * Add a static public or private key to "wg_static_keys".
+ */
+static void
+wg_add_static_key(const wg_qqword *tmp_key, gboolean is_private)
+{
+ wg_skey_t *key = g_new0(wg_skey_t, 1);
+ if (is_private) {
+ set_private_key(&key->priv_key, tmp_key);
+ priv_to_pub(&key->pub_key, tmp_key);
+ } else {
+ key->pub_key = *tmp_key;
+ }
+
+ // If a previous pubkey exists, skip adding the new key. Do add the
+ // secret if it has become known in meantime.
+ wg_skey_t *oldkey = (wg_skey_t *)g_hash_table_lookup(wg_static_keys, &key->pub_key);
+ if (oldkey) {
+ if (!has_private_key(&oldkey->priv_key) && is_private) {
+ oldkey->priv_key = key->priv_key;
+ }
+ g_free(key);
+ return;
+ }
+
+ // New key, precompute the MAC1 label.
+ wg_mac1_key(&key->pub_key, &key->mac1_key);
+
+ g_hash_table_insert(wg_static_keys, &key->pub_key, key);
+}
+
+/* UAT and key configuration. {{{ */
+static gboolean
+wg_key_uat_record_update_cb(void *r, char **error)
+{
+ wg_key_uat_record_t *rec = (wg_key_uat_record_t *)r;
+ wg_qqword key;
+
+ /* Check for valid base64-encoding. */
+ if (!decode_base64_key(&key, rec->key)) {
+ *error = g_strdup("Invalid key");
+ return FALSE;
+ }
+
+ return TRUE;
+}
+
+static void
+wg_key_uat_apply(void)
+{
+ if (!wg_static_keys) {
+ // The first field of "wg_skey_t" is the pubkey (and the table key),
+ // its initial four bytes should be good enough as key hash.
+ wg_static_keys = g_hash_table_new_full(g_int_hash, wg_pubkey_equal, NULL, g_free);
+ } else {
+ g_hash_table_remove_all(wg_static_keys);
+ }
+
+ /* Convert base64-encoded strings to wg_skey_t and derive pubkey. */
+ for (guint i = 0; i < num_wg_key_records; i++) {
+ wg_key_uat_record_t *rec = &wg_key_records[i];
+ wg_qqword tmp_key; /* Either public or private, not sure yet. */
+
+ /* Populate public (and private) keys. */
+ gboolean decoded = decode_base64_key(&tmp_key, rec->key);
+ DISSECTOR_ASSERT(decoded);
+ wg_add_static_key(&tmp_key, rec->key_type == WG_KEY_UAT_PRIVATE);
+ }
+}
+
+static void
+wg_key_uat_reset(void)
+{
+ /* Erase keys when the UAT is unloaded. */
+ g_hash_table_destroy(wg_static_keys);
+ wg_static_keys = NULL;
+}
+
+UAT_VS_DEF(wg_key_uat, key_type, wg_key_uat_record_t, guint, WG_KEY_UAT_PUBLIC, "Public")
+UAT_CSTRING_CB_DEF(wg_key_uat, key, wg_key_uat_record_t)
+/* UAT and key configuration. }}} */
+#endif /* WG_DECRYPTION_SUPPORTED */
+
+
static void
wg_sessions_insert(guint32 id, wg_session_t *session)
{
return NULL;
}
+#ifdef WG_DECRYPTION_SUPPORTED
+/*
+ * Finds the static public key for the receiver of this message based on the
+ * MAC1 value.
+ * TODO on PINFO_FD_VISITED, reuse previously discovered keys from session?
+ */
+static const wg_skey_t *
+wg_mac1_key_probe(tvbuff_t *tvb, gboolean is_initiation)
+{
+ const int mac1_offset = is_initiation ? 116 : 60;
+
+ // Shortcut: skip MAC1 validation if no pubkeys are configured.
+ if (g_hash_table_size(wg_static_keys) == 0) {
+ return NULL;
+ }
+
+ const guint8 *mac1_msgdata = tvb_get_ptr(tvb, 0, mac1_offset);
+ const guint8 *mac1_output = tvb_get_ptr(tvb, mac1_offset, 16);
+ // Find public key that matches the 16-byte MAC1 field.
+ GHashTableIter iter;
+ gpointer value;
+ g_hash_table_iter_init(&iter, wg_static_keys);
+ while (g_hash_table_iter_next(&iter, NULL, &value)) {
+ const wg_skey_t *skey = (wg_skey_t *)value;
+ if (wg_mac_verify(&skey->mac1_key, mac1_msgdata, (guint)mac1_offset, mac1_output)) {
+ return skey;
+ }
+ }
+
+ return NULL;
+}
+#endif /* WG_DECRYPTION_SUPPORTED */
+
static void
wg_dissect_pubkey(proto_tree *tree, tvbuff_t *tvb, int offset, gboolean is_ephemeral)
proto_tree_add_string(tree, hf_id, tvb, offset, 32, key_str);
}
+#ifdef WG_DECRYPTION_SUPPORTED
+static void
+wg_dissect_mac1_pubkey(proto_tree *tree, tvbuff_t *tvb, const wg_skey_t *skey)
+{
+ proto_item *ti;
+
+ if (!skey) {
+ return;
+ }
+
+ ti = proto_tree_add_string(tree, hf_wg_receiver_pubkey, tvb, 0, 0, pubkey_to_string(&skey->pub_key));
+ PROTO_ITEM_SET_GENERATED(ti);
+ proto_tree *key_tree = proto_item_add_subtree(ti, ett_key_info);
+ ti = proto_tree_add_boolean(key_tree, hf_wg_receiver_pubkey_known_privkey, tvb, 0, 0, !!has_private_key(&skey->priv_key));
+ PROTO_ITEM_SET_GENERATED(ti);
+}
+#endif /* WG_DECRYPTION_SUPPORTED */
+
static int
wg_dissect_handshake_initiation(tvbuff_t *tvb, packet_info *pinfo, proto_tree *wg_tree, wg_packet_info_t *wg_pinfo)
{
guint32 sender_id;
proto_item *ti;
+#ifdef WG_DECRYPTION_SUPPORTED
+ const wg_skey_t *skey_r = wg_mac1_key_probe(tvb, TRUE);
+#endif /* WG_DECRYPTION_SUPPORTED */
+
proto_tree_add_item_ret_uint(wg_tree, hf_wg_sender, tvb, 4, 4, ENC_LITTLE_ENDIAN, &sender_id);
col_append_fstr(pinfo->cinfo, COL_INFO, ", sender=0x%08X", sender_id);
wg_dissect_pubkey(wg_tree, tvb, 8, TRUE);
proto_tree_add_item(wg_tree, hf_wg_encrypted_static, tvb, 40, 32 + AUTH_TAG_LENGTH, ENC_NA);
proto_tree_add_item(wg_tree, hf_wg_encrypted_timestamp, tvb, 88, 12 + AUTH_TAG_LENGTH, ENC_NA);
proto_tree_add_item(wg_tree, hf_wg_mac1, tvb, 116, 16, ENC_NA);
+#ifdef WG_DECRYPTION_SUPPORTED
+ wg_dissect_mac1_pubkey(wg_tree, tvb, skey_r);
+#endif /* WG_DECRYPTION_SUPPORTED */
proto_tree_add_item(wg_tree, hf_wg_mac2, tvb, 132, 16, ENC_NA);
if (!PINFO_FD_VISITED(pinfo)) {
guint32 sender_id, receiver_id;
proto_item *ti;
+#ifdef WG_DECRYPTION_SUPPORTED
+ const wg_skey_t *skey_i = wg_mac1_key_probe(tvb, FALSE);
+#endif /* WG_DECRYPTION_SUPPORTED */
+
proto_tree_add_item_ret_uint(wg_tree, hf_wg_sender, tvb, 4, 4, ENC_LITTLE_ENDIAN, &sender_id);
col_append_fstr(pinfo->cinfo, COL_INFO, ", sender=0x%08X", sender_id);
proto_tree_add_item_ret_uint(wg_tree, hf_wg_receiver, tvb, 8, 4, ENC_LITTLE_ENDIAN, &receiver_id);
wg_dissect_pubkey(wg_tree, tvb, 12, TRUE);
proto_tree_add_item(wg_tree, hf_wg_encrypted_empty, tvb, 44, 16, ENC_NA);
proto_tree_add_item(wg_tree, hf_wg_mac1, tvb, 60, 16, ENC_NA);
+#ifdef WG_DECRYPTION_SUPPORTED
+ wg_dissect_mac1_pubkey(wg_tree, tvb, skey_i);
+#endif /* WG_DECRYPTION_SUPPORTED */
proto_tree_add_item(wg_tree, hf_wg_mac2, tvb, 76, 16, ENC_NA);
wg_session_t *session;
void
proto_register_wg(void)
{
+#ifdef WG_DECRYPTION_SUPPORTED
+ module_t *wg_module;
+#endif /* WG_DECRYPTION_SUPPORTED */
expert_module_t *expert_wg;
static hf_register_info hf[] = {
FT_FRAMENUM, BASE_NONE, FRAMENUM_TYPE(FT_FRAMENUM_REQUEST), 0x0,
"This is a response to the initiation message in this frame", HFILL }
},
+
+ /* Additional fields. */
+ { &hf_wg_receiver_pubkey,
+ { "Receiver Static Public Key", "wg.receiver_pubkey",
+ FT_STRING, BASE_NONE, NULL, 0x0,
+ "Public key of the receiver (matched based on MAC1)", HFILL }
+ },
+ { &hf_wg_receiver_pubkey_known_privkey,
+ { "Has Private Key", "wg.receiver_pubkey.known_privkey",
+ FT_BOOLEAN, BASE_NONE, NULL, 0x0,
+ "Whether the corresponding private key is known (configured via prefs)", HFILL }
+ },
};
static gint *ett[] = {
&ett_wg,
+ &ett_key_info,
};
static ei_register_info ei[] = {
},
};
+#ifdef WG_DECRYPTION_SUPPORTED
+ /* UAT for header fields */
+ static uat_field_t wg_key_uat_fields[] = {
+ UAT_FLD_VS(wg_key_uat, key_type, "Key type", wg_key_uat_type_vals, "Public or Private"),
+ UAT_FLD_CSTRING(wg_key_uat, key, "Key", "Base64-encoded key"),
+ UAT_END_FIELDS
+ };
+#endif /* WG_DECRYPTION_SUPPORTED */
+
proto_wg = proto_register_protocol("WireGuard Protocol", "WireGuard", "wg");
proto_register_field_array(proto_wg, hf, array_length(hf));
register_dissector("wg", dissect_wg, proto_wg);
+#ifdef WG_DECRYPTION_SUPPORTED
+ wg_module = prefs_register_protocol(proto_wg, NULL);
+
+ uat_t *wg_keys_uat = uat_new("WireGuard static keys",
+ sizeof(wg_key_uat_record_t),
+ "wg_keys", /* filename */
+ TRUE, /* from_profile */
+ &wg_key_records, /* data_ptr */
+ &num_wg_key_records, /* numitems_ptr */
+ UAT_AFFECTS_DISSECTION, /* affects dissection of packets, but not set of named fields */
+ NULL, /* Help section (currently a wiki page) */
+ NULL, /* copy_cb */
+ wg_key_uat_record_update_cb, /* update_cb */
+ NULL, /* free_cb */
+ wg_key_uat_apply, /* post_update_cb */
+ wg_key_uat_reset, /* reset_cb */
+ wg_key_uat_fields);
+
+ prefs_register_uat_preference(wg_module, "keys",
+ "WireGuard static keys",
+ "A table of long-term static keys to enable WireGuard peer identification or partial decryption",
+ wg_keys_uat);
+#endif /* WG_DECRYPTION_SUPPORTED */
+
register_init_routine(wg_init);
sessions = wmem_map_new_autoreset(wmem_epan_scope(), wmem_file_scope(), g_direct_hash, g_direct_equal);
}
git.samba.org / metze / wireshark / wip.git / commitdiff