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QUIC: dissect unprotected fields in Long Header (draft -17) 

Create ciphers earlier in the long header dissection process such that
the flag byte can be decrypted, dissect Reserved and Packet Number
Length fields.

Bug: 13881
Change-Id: I233ee1cab9783f00a4ed6e1e3689135f979ec820
Reviewed-on: https://code.wireshark.org/review/31642
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Tested-by: Petri Dish Buildbot
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>
This commit is contained in:
Peter Wu 2019-01-21 01:10:31 +01:00 committed by Alexis La Goutte
parent 7acb5caa9f
commit 295b9883e5
1 changed files with 78 additions and 43 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

121
epan/dissectors/packet-quic.c
View File

@ -46,6 +46,8 @@ static int proto_quic = -1;
static int hf_quic_connection_number = -1;
static int hf_quic_header_form = -1;
static int hf_quic_long_packet_type = -1;
static int hf_quic_long_reserved = -1;
static int hf_quic_packet_number_length = -1;
static int hf_quic_dcid = -1;
static int hf_quic_scid = -1;
static int hf_quic_dcil = -1;
@ -438,6 +440,20 @@ static const value_string quic_application_error_code_vals[] = {
{ 0, NULL }
};
static const value_string quic_packet_number_lengths[] = {
{ 0, "1 bytes" },
{ 1, "2 bytes" },
{ 2, "3 bytes" },
{ 3, "4 bytes" },
{ 0, NULL }
};
static void
quic_extract_header(tvbuff_t *tvb, guint8 *long_packet_type, guint32 *version,
quic_cid_t *dcid, quic_cid_t *scid);
static void
quic_cipher_reset(quic_cipher *cipher)
{
@ -1896,7 +1912,7 @@ dissect_quic_long_header(tvbuff_t *tvb, packet_info *pinfo, proto_tree *quic_tre
quic_datagram *dgram_info, quic_packet_info_t *quic_packet)
{
guint offset = 0;
guint32 long_packet_type;
guint8 long_packet_type;
guint32 version;
quic_cid_t dcid = {.len=0}, scid = {.len=0};
guint32 len_token_length;
@ -1909,11 +1925,59 @@ dissect_quic_long_header(tvbuff_t *tvb, packet_info *pinfo, proto_tree *quic_tre
quic_cipher *cipher = NULL;
proto_item *ti;
proto_tree_add_item_ret_uint(quic_tree, hf_quic_long_packet_type, tvb, offset, 1, ENC_NA, &long_packet_type);
quic_extract_header(tvb, &long_packet_type, &version, &dcid, &scid);
#ifdef HAVE_LIBGCRYPT_AEAD
if (conn) {
if (long_packet_type == QUIC_LPT_INITIAL) {
cipher = !from_server ? &conn->client_initial_cipher : &conn->server_initial_cipher;
} else if (long_packet_type == QUIC_LPT_HANDSHAKE) {
cipher = !from_server ? &conn->client_handshake_cipher : &conn->server_handshake_cipher;
}
}
/* Prepare the Initial/Handshake cipher for header/payload decryption. */
if (!PINFO_FD_VISITED(pinfo) && conn && cipher) {
const gchar *error = NULL;
if (long_packet_type == QUIC_LPT_INITIAL && !from_server &&
!memcmp(&dcid, &conn->client_dcid_initial, sizeof(quic_cid_t))) {
/* Create new decryption context based on the Client Connection
* ID from the *very first* Client Initial packet. */
quic_create_initial_decoders(&dcid, &error, conn);
} else if (long_packet_type == QUIC_LPT_HANDSHAKE) {
if (!cipher->hp_cipher) {
quic_create_decoders(pinfo, conn, cipher, from_server, TLS_SECRET_HANDSHAKE, &error);
}
}
if (!error) {
guint32 pkn32 = 0;
int hp_cipher_algo = long_packet_type != QUIC_LPT_INITIAL && conn ? conn->cipher_algo : GCRY_CIPHER_AES128;
guint pn_offset = 6 + dcid.len + scid.len;
if (long_packet_type == QUIC_LPT_INITIAL) {
pn_offset += tvb_get_varint(tvb, pn_offset, 8, &token_length, ENC_VARINT_QUIC);
pn_offset += (guint)token_length;
}
pn_offset += tvb_get_varint(tvb, pn_offset, 8, &payload_length, ENC_VARINT_QUIC);
if (quic_decrypt_header(tvb, pn_offset, cipher->hp_cipher, hp_cipher_algo, &first_byte, &pkn32)) {
quic_set_full_packet_number(conn, quic_packet, from_server, first_byte, pkn32);
quic_packet->first_byte = first_byte;
} else {
error = "Header deprotection failed";
}
}
if (error) {
quic_packet->decryption.error = wmem_strdup(wmem_file_scope(), error);
}
}
#endif /* !HAVE_LIBGCRYPT_AEAD */
proto_tree_add_item(quic_tree, hf_quic_long_packet_type, tvb, offset, 1, ENC_NA);
if (quic_packet->pkn_len) {
proto_tree_add_uint(quic_tree, hf_quic_long_reserved, tvb, offset, 1, first_byte);
proto_tree_add_uint(quic_tree, hf_quic_packet_number_length, tvb, offset, 1, first_byte);
}
offset += 1;
col_set_str(pinfo->cinfo, COL_INFO, val_to_str_const(long_packet_type, quic_long_packet_type_vals, "Long Header"));
offset = dissect_quic_long_header_common(tvb, pinfo, quic_tree, offset, quic_packet, &version, &dcid, &scid);
offset = dissect_quic_long_header_common(tvb, pinfo, quic_tree, offset, quic_packet, NULL, &dcid, &scid);
if (long_packet_type == QUIC_LPT_INITIAL) {
proto_tree_add_item_ret_varint(quic_tree, hf_quic_token_length, tvb, offset, -1, ENC_VARINT_QUIC, &token_length, &len_token_length);
@ -1928,51 +1992,11 @@ dissect_quic_long_header(tvbuff_t *tvb, packet_info *pinfo, proto_tree *quic_tre
proto_tree_add_item_ret_varint(quic_tree, hf_quic_length, tvb, offset, -1, ENC_VARINT_QUIC, &payload_length, &len_payload_length);
offset += len_payload_length;
#ifdef HAVE_LIBGCRYPT_AEAD
// TODO the following code is already necessary to unmask the first byte. It
// should probably moved above, but then DCID needs to be extracted
// first. The version also needs to be checked.
if (conn) {
if (long_packet_type == QUIC_LPT_INITIAL) {
cipher = !from_server ? &conn->client_initial_cipher : &conn->server_initial_cipher;
} else if (long_packet_type == QUIC_LPT_HANDSHAKE) {
cipher = !from_server ? &conn->client_handshake_cipher : &conn->server_handshake_cipher;
}
}
/* Build handshake cipher now for PKN (and handshake) decryption. */
if (!PINFO_FD_VISITED(pinfo) && conn) {
const gchar *error = NULL;
if (long_packet_type == QUIC_LPT_INITIAL && !from_server &&
!memcmp(&dcid, &conn->client_dcid_initial, sizeof(quic_cid_t))) {
/* Create new decryption context based on the Client Connection
* ID from the *very first* Client Initial packet. */
quic_create_initial_decoders(&dcid, &error, conn);
} else if (long_packet_type == QUIC_LPT_HANDSHAKE) {
if (!cipher->hp_cipher) {
quic_create_decoders(pinfo, conn, cipher, from_server, TLS_SECRET_HANDSHAKE, &error);
}
}
if (error) {
quic_packet->decryption.error = wmem_strdup(wmem_file_scope(), error);
}
}
#endif /* !HAVE_LIBGCRYPT_AEAD */
if (quic_packet->decryption.error) {
expert_add_info_format(pinfo, quic_tree, &ei_quic_decryption_failed,
"Failed to create decryption context: %s", quic_packet->decryption.error);
return offset;
}
#ifdef HAVE_LIBGCRYPT_AEAD
if (!PINFO_FD_VISITED(pinfo) && conn && cipher) {
guint32 pkn32 = 0;
int hp_cipher_algo = long_packet_type != QUIC_LPT_INITIAL && conn ? conn->cipher_algo : GCRY_CIPHER_AES128;
if (quic_decrypt_header(tvb, offset, cipher->hp_cipher, hp_cipher_algo, &first_byte, &pkn32)) {
quic_set_full_packet_number(conn, quic_packet, from_server, first_byte, pkn32);
// TODO this is unused for LPT, see also above for the required cipher refactor.
quic_packet->first_byte = first_byte;
}
}
#endif /* !HAVE_LIBGCRYPT_AEAD */
if (!conn || quic_packet->pkn_len == 0) {
// if not part of a connection, the full PKN cannot be reconstructed.
expert_add_info_format(pinfo, quic_tree, &ei_quic_decryption_failed, "Failed to decrypt packet number");
@ -2032,6 +2056,7 @@ dissect_quic_short_header(tvbuff_t *tvb, packet_info *pinfo, proto_tree *quic_tr
key_phase = (first_byte & SH_KP) != 0;
proto_tree_add_uint(quic_tree, hf_quic_short_reserved, tvb, offset, 1, first_byte);
proto_tree_add_boolean(quic_tree, hf_quic_key_phase, tvb, offset, 1, key_phase);
proto_tree_add_uint(quic_tree, hf_quic_packet_number_length, tvb, offset, 1, first_byte);
}
offset += 1;
@ -2405,6 +2430,16 @@ proto_register_quic(void)
FT_UINT8, BASE_DEC, VALS(quic_long_packet_type_vals), 0x30,
"Long Header Packet Type", HFILL }
},
{ &hf_quic_long_reserved,
{ "Reserved", "quic.long.reserved",
FT_UINT8, BASE_DEC, NULL, 0x0c,
"Reserved bits (protected using header protection)", HFILL }
},
{ &hf_quic_packet_number_length,
{ "Packet Number Length", "quic.packet_number_length",
FT_UINT8, BASE_DEC, VALS(quic_packet_number_lengths), 0x03,
"Packet Number field length (protected using header protection)", HFILL }
},
{ &hf_quic_dcid,
{ "Destination Connection ID", "quic.dcid",
FT_BYTES, BASE_NONE, NULL, 0x0,