[PATCH v3 1/2] EAP-TTLS/PEAP peer: fix failure when using session tickets under TLS 1.3

[Alexander Clouter]

eap_peer does not expect data present when beginning phase2 in
EAP-{TTLS,PEAP} but in TLS 1.3 session tickets are sent after the handshake
completes.

There are several strategies that can be used to handle this, but this patch
picks up from the discussion[1] and implements the proposed use of
SSL_MODE_AUTO_RETRY.

Signed-off-by: Alexander Clouter <alex at digriz.org.uk>

[1] https://www.spinics.net/lists/hostap/msg05376.html

---
 src/crypto/tls_openssl.c | 17 +++++++++++++----
 src/eap_peer/eap_peap.c  |  4 ++++
 src/eap_peer/eap_ttls.c  |  5 +++++
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/src/crypto/tls_openssl.c b/src/crypto/tls_openssl.c
index f7dfecbbf..6b552293e 100644
--- a/src/crypto/tls_openssl.c
+++ b/src/crypto/tls_openssl.c
@@ -1045,6 +1045,8 @@ void * tls_init(const struct tls_config *conf)
 	SSL_CTX_set_options(ssl, SSL_OP_NO_SSLv2);
 	SSL_CTX_set_options(ssl, SSL_OP_NO_SSLv3);
 
+	SSL_CTX_set_mode(ssl, SSL_MODE_AUTO_RETRY);
+
 #ifdef SSL_MODE_NO_AUTO_CHAIN
 	/* Number of deployed use cases assume the default OpenSSL behavior of
 	 * auto chaining the local certificate is in use. BoringSSL removed this
@@ -4543,10 +4545,17 @@ struct wpabuf * tls_connection_decrypt(void *tls_ctx,
 		return NULL;
 	res = SSL_read(conn->ssl, wpabuf_mhead(buf), wpabuf_size(buf));
 	if (res < 0) {
-		tls_show_errors(MSG_INFO, __func__,
-				"Decryption failed - SSL_read");
-		wpabuf_free(buf);
-		return NULL;
+		int err = SSL_get_error(conn->ssl, res);
+		if (err == SSL_ERROR_WANT_READ) {
+			wpa_printf(MSG_DEBUG, "SSL: SSL_connect - want "
+				   "more data");
+			res = 0;
+		} else {
+			tls_show_errors(MSG_INFO, __func__,
+					"Decryption failed - SSL_read");
+			wpabuf_free(buf);
+			return NULL;
+		}
 	}
 	wpabuf_put(buf, res);
 
diff --git a/src/eap_peer/eap_peap.c b/src/eap_peer/eap_peap.c
index 7bcba4de2..cb34a0fc3 100644
--- a/src/eap_peer/eap_peap.c
+++ b/src/eap_peer/eap_peap.c
@@ -819,6 +819,10 @@ static int eap_peap_decrypt(struct eap_sm *sm, struct eap_peap_data *data,
 	res = eap_peer_tls_decrypt(sm, &data->ssl, in_data, &in_decrypted);
 	if (res)
 		return res;
+	if (wpabuf_len(in_decrypted) == 0) {
+		wpabuf_free(in_decrypted);
+		return 1;
+	}
 
 continue_req:
 	wpa_hexdump_buf(MSG_DEBUG, "EAP-PEAP: Decrypted Phase 2 EAP",
diff --git a/src/eap_peer/eap_ttls.c b/src/eap_peer/eap_ttls.c
index 642d179c6..3bf1e97e6 100644
--- a/src/eap_peer/eap_ttls.c
+++ b/src/eap_peer/eap_ttls.c
@@ -1441,6 +1441,7 @@ static int eap_ttls_decrypt(struct eap_sm *sm, struct eap_ttls_data *data,
 
 	if ((in_data == NULL || wpabuf_len(in_data) == 0) &&
 	    data->phase2_start) {
+start:
 		return eap_ttls_phase2_start(sm, data, ret, identifier,
 					     out_data);
 	}
@@ -1455,6 +1456,10 @@ static int eap_ttls_decrypt(struct eap_sm *sm, struct eap_ttls_data *data,
 	retval = eap_peer_tls_decrypt(sm, &data->ssl, in_data, &in_decrypted);
 	if (retval)
 		goto done;
+	if (wpabuf_len(in_decrypted) == 0) {
+		wpabuf_free(in_decrypted);
+		goto start;
+	}
 
 continue_req:
 	data->phase2_start = 0;
-- 
2.20.1