From feb9e31c40c49de6384dd0413685e9b5a15adc99 Mon Sep 17 00:00:00 2001 From: Matt Caswell Date: Wed, 17 Apr 2019 11:09:05 +0100 Subject: [PATCH] Defer sending a KeyUpdate until after pending writes are complete If we receive a KeyUpdate message (update requested) from the peer while we are in the middle of a write, we should defer sending the responding KeyUpdate message until after the current write is complete. We do this by waiting to send the KeyUpdate until the next time we write and there is no pending write data. This does imply a subtle change in behaviour. Firstly the responding KeyUpdate message won't be sent straight away as it is now. Secondly if the peer sends multiple KeyUpdates without us doing any writing then we will only send one response, as opposed to previously where we sent a response for each KeyUpdate received. Fixes #8677 Reviewed-by: Ben Kaduk (Merged from https://github.com/openssl/openssl/pull/8773) --- ssl/record/rec_layer_s3.c | 7 +++++++ ssl/statem/statem_clnt.c | 6 ------ ssl/statem/statem_lib.c | 7 ++----- ssl/statem/statem_srvr.c | 6 ------ 4 files changed, 9 insertions(+), 17 deletions(-) diff --git a/ssl/record/rec_layer_s3.c b/ssl/record/rec_layer_s3.c index 64e132aac0..a9911328e6 100644 --- a/ssl/record/rec_layer_s3.c +++ b/ssl/record/rec_layer_s3.c @@ -377,6 +377,13 @@ int ssl3_write_bytes(SSL *s, int type, const void *buf_, size_t len, s->rlayer.wnum = 0; + /* + * If we are supposed to be sending a KeyUpdate then go into init unless we + * have writes pending - in which case we should finish doing that first. + */ + if (wb->left == 0 && s->key_update != SSL_KEY_UPDATE_NONE) + ossl_statem_set_in_init(s, 1); + /* * When writing early data on the server side we could be "in_init" in * between receiving the EoED and the CF - but we don't want to handle those diff --git a/ssl/statem/statem_clnt.c b/ssl/statem/statem_clnt.c index 1be7c5745c..d096143530 100644 --- a/ssl/statem/statem_clnt.c +++ b/ssl/statem/statem_clnt.c @@ -474,12 +474,6 @@ static WRITE_TRAN ossl_statem_client13_write_transition(SSL *s) return WRITE_TRAN_CONTINUE; case TLS_ST_CR_KEY_UPDATE: - if (s->key_update != SSL_KEY_UPDATE_NONE) { - st->hand_state = TLS_ST_CW_KEY_UPDATE; - return WRITE_TRAN_CONTINUE; - } - /* Fall through */ - case TLS_ST_CW_KEY_UPDATE: case TLS_ST_CR_SESSION_TICKET: case TLS_ST_CW_FINISHED: diff --git a/ssl/statem/statem_lib.c b/ssl/statem/statem_lib.c index 033ea613c5..8c7d5e2a60 100644 --- a/ssl/statem/statem_lib.c +++ b/ssl/statem/statem_lib.c @@ -643,12 +643,9 @@ MSG_PROCESS_RETURN tls_process_key_update(SSL *s, PACKET *pkt) /* * If we get a request for us to update our sending keys too then, we need * to additionally send a KeyUpdate message. However that message should - * not also request an update (otherwise we get into an infinite loop). We - * ignore a request for us to update our sending keys too if we already - * sent close_notify. + * not also request an update (otherwise we get into an infinite loop). */ - if (updatetype == SSL_KEY_UPDATE_REQUESTED - && (s->shutdown & SSL_SENT_SHUTDOWN) == 0) + if (updatetype == SSL_KEY_UPDATE_REQUESTED) s->key_update = SSL_KEY_UPDATE_NOT_REQUESTED; if (!tls13_update_key(s, 0)) { diff --git a/ssl/statem/statem_srvr.c b/ssl/statem/statem_srvr.c index fe495a3a68..6504f4f74e 100644 --- a/ssl/statem/statem_srvr.c +++ b/ssl/statem/statem_srvr.c @@ -503,12 +503,6 @@ static WRITE_TRAN ossl_statem_server13_write_transition(SSL *s) return WRITE_TRAN_CONTINUE; case TLS_ST_SR_KEY_UPDATE: - if (s->key_update != SSL_KEY_UPDATE_NONE) { - st->hand_state = TLS_ST_SW_KEY_UPDATE; - return WRITE_TRAN_CONTINUE; - } - /* Fall through */ - case TLS_ST_SW_KEY_UPDATE: st->hand_state = TLS_ST_OK; return WRITE_TRAN_CONTINUE; -- 2.25.1