KTLS: Add using_ktls helper variable in ssl3_get_record().

When KTLS receive is enabled, pending data may still be present due to
read ahead.  This data must still be processed the same as records
received without KTLS.  To ease readability (especially in
consideration of additional checks which will be added for TLS 1.3),
add a helper variable 'using_ktls' that is true when the KTLS receive
path is being used to receive a record.

Co-authored-by: Dmitry Podgorny <pasis.ua@gmail.com>

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/17942)

1 files changed, 10 insertions, 10 deletions

diff --git a/ssl/record/ssl3_record.c b/ssl/record/ssl3_record.c
index 5534814305..8eb9497e06 100644
--- a/ssl/record/ssl3_record.c
+++ b/ssl/record/ssl3_record.c
@@ -185,18 +185,23 @@ int ssl3_get_record(SSL *s)
     int imac_size;
     size_t num_recs = 0, max_recs, j;
     PACKET pkt, sslv2pkt;
-    int is_ktls_left;
+    int using_ktls;
     SSL_MAC_BUF *macbufs = NULL;
     int ret = -1;
 
     rr = RECORD_LAYER_get_rrec(&s->rlayer);
     rbuf = RECORD_LAYER_get_rbuf(&s->rlayer);
-    is_ktls_left = (SSL3_BUFFER_get_left(rbuf) > 0);
     max_recs = s->max_pipelines;
     if (max_recs == 0)
         max_recs = 1;
     sess = s->session;
 
+    /*
+     * KTLS reads full records. If there is any data left,
+     * then it is from before enabling ktls.
+     */
+    using_ktls = BIO_get_ktls_recv(s->rbio) && SSL3_BUFFER_get_left(rbuf) == 0;
+
     do {
         thisrr = &rr[num_recs];
 
@@ -409,7 +414,7 @@ int ssl3_get_record(SSL *s)
 #endif
 
             /* KTLS may use all of the buffer */
-            if (BIO_get_ktls_recv(s->rbio) && !is_ktls_left)
+            if (using_ktls)
                 len = SSL3_BUFFER_get_left(rbuf);
 
             if (thisrr->length > len) {
@@ -518,11 +523,7 @@ int ssl3_get_record(SSL *s)
         return 1;
     }
 
-    /*
-     * KTLS reads full records. If there is any data left,
-     * then it is from before enabling ktls
-     */
-    if (BIO_get_ktls_recv(s->rbio) && !is_ktls_left)
+    if (using_ktls)
         goto skip_decryption;
 
     if (s->read_hash != NULL) {
@@ -723,8 +724,7 @@ int ssl3_get_record(SSL *s)
          * Therefore we have to rely on KTLS to check the plaintext length
          * limit in the kernel.
          */
-        if (thisrr->length > SSL3_RT_MAX_PLAIN_LENGTH
-                && (!BIO_get_ktls_recv(s->rbio) || is_ktls_left)) {
+        if (thisrr->length > SSL3_RT_MAX_PLAIN_LENGTH && !using_ktls) {
             SSLfatal(s, SSL_AD_RECORD_OVERFLOW, SSL_R_DATA_LENGTH_TOO_LONG);
             goto end;
         }