osmith
/
wireshark
forked from osmocom/wireshark
1
0
Fork 0
Code Pull Requests Releases Wiki Activity

QUIC: improve handling of unencrypted padding data 

0af60377b4 added an heuristic to detect (unencrypted) padding data;
it is based on the fact that all coalesced QUIC packets must have the
same CID.
Unfortunately it doesn't work when the CID length is 0.

Treat decryption error of SH packets as a non fatal error, report them
as possible padding data misdetectd as coalesced packets and try
decrypting next traffic.

Close #17383

(cherry picked from commit 389a899a18)
This commit is contained in:
Nardi Ivan 2021-05-17 19:42:18 +02:00 committed by Wireshark GitLab Utility
parent dd0c60a001
commit 4a17759938
1 changed files with 15 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
epan/dissectors/packet-quic.c
View File

@ -2434,15 +2434,21 @@ quic_get_1rtt_hp_cipher(packet_info *pinfo, quic_info_data_t *quic_info, gboolea
if (!quic_info->client_pp.next_secret) {
/* Query TLS for the cipher suite. */
if (!tls_get_cipher_info(pinfo, 0, &quic_info->cipher_algo, &quic_info->cipher_mode, &quic_info->hash_algo)) {
// No previous TLS handshake found or unsupported ciphers, fail.
// This is an optimization that allows skipping checks for future
// packets in case the capture starts in midst of a connection where
// the handshake is not present.
// If this breaks decryption because packets prior to the Server
// Hello are somehow misdetected as Short Packet, then this
// optimization should probably be removed.
quic_info->skip_decryption = TRUE;
*error = "Missing TLS handshake or unsupported ciphers";
/* We end up here if:
* no previous TLS handshake is found
* the used ciphers are unsupported
* some (unencrypted) padding is misdetected as SH coalesced packet
Because of the third scenario, we can't set quic_info->skip_decryption
to TRUE; otherwise we will stop decrypting the entire session, even if
we are able to.
Unfortunately, this way, we lost the optimization that allows skipping checks
for future packets in case the capture starts in midst of a
connection where the handshake is not present.
Note that even if we have a basic logic to detect unencrypted padding (via
check_dcid_on_coalesced_packet()), there is not a proper way to detect it
other than checking if the decryption successed
*/
*error = "Missing TLS handshake, unsupported ciphers or padding";
return NULL;
}