commit e664a534afc3a03a14190328557fa88341a60300
author David Benjamin <davidben@google.com> Thu Jul 20 20:19:36 2017 -0400
committer CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org> Tue Jul 25 18:53:48 2017 +0000
tree 4b7ed91139acbcfeb77adedb58eb1dec27b976d3
parent 2eee1314014c30ee00012d0caa9304ab17994541

Return null from SSL_get0_peer_certificates if unauthenticated.

SSL_get0_peer_certificates is documented to return NULL if the peer was
anonymous, but it actually returns a non-NULL empty list (except in SSL
3.0 where the Certificate message and thus ssl_parse_cert_chain is
skipped).

Make the implementation match the documentation.

Change-Id: Ib3e25d2155f316cc5e9eb3ab7f74b78e08b8a86b
Reviewed-on: https://boringssl-review.googlesource.com/18226
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>

ssl/tls13_both.cc

diff --git a/ssl/tls13_both.cc b/ssl/tls13_both.cc
index 338975b..627f038 100644
--- a/ssl/tls13_both.cc
+++ b/ssl/tls13_both.cc
@@ -196,7 +196,9 @@
   CBS cbs, context, certificate_list;
   CBS_init(&cbs, ssl->init_msg, ssl->init_num);
   if (!CBS_get_u8_length_prefixed(&cbs, &context) ||
-      CBS_len(&context) != 0) {
+      CBS_len(&context) != 0 ||
+      !CBS_get_u24_length_prefixed(&cbs, &certificate_list) ||
+      CBS_len(&cbs) != 0) {
     ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
     OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
     return 0;
@@ -209,12 +211,6 @@
     return 0;
   }
 
-  if (!CBS_get_u24_length_prefixed(&cbs, &certificate_list)) {
-    ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
-    OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
-    return 0;
-  }
-
   const bool retain_sha256 =
       ssl->server && ssl->retain_only_sha256_of_client_certs;
   UniquePtr<EVP_PKEY> pkey;
@@ -326,10 +322,10 @@
     }
   }
 
-  if (CBS_len(&cbs) != 0) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
-    ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
-    return 0;
+  /* Store a null certificate list rather than an empty one if the peer didn't
+   * send certificates. */
+  if (sk_CRYPTO_BUFFER_num(certs.get()) == 0) {
+    certs.reset();
   }
 
   hs->peer_pubkey = std::move(pkey);