Avoid repeatedly scanning the list of extensions
[openssl.git] / ssl / statem / statem_srvr.c
index 33808ed9f488dc6d1953bea2096c7fdb29f67217..5aa395f4068aa8a0aaa55e5f467b4d6df41a1096 100644 (file)
@@ -61,6 +61,7 @@
 #include <openssl/bn.h>
 #include <openssl/md5.h>
 
+static int tls_construct_encrypted_extensions(SSL *s, WPACKET *pkt);
 static STACK_OF(SSL_CIPHER) *ssl_bytes_to_cipher_list(SSL *s,
                                                       PACKET *cipher_suites,
                                                       STACK_OF(SSL_CIPHER)
@@ -408,6 +409,10 @@ static WRITE_TRAN ossl_statem_server13_write_transition(SSL *s)
         return WRITE_TRAN_CONTINUE;
 
     case TLS_ST_SW_SRVR_HELLO:
+        st->hand_state = TLS_ST_SW_ENCRYPTED_EXTENSIONS;
+        return WRITE_TRAN_CONTINUE;
+
+    case TLS_ST_SW_ENCRYPTED_EXTENSIONS:
         if (s->hit)
             st->hand_state = TLS_ST_SW_FINISHED;
         else if (send_certificate_request(s))
@@ -855,6 +860,11 @@ int ossl_statem_server_construct_message(SSL *s, WPACKET *pkt,
         *confunc = tls_construct_finished;
         *mt = SSL3_MT_FINISHED;
         break;
+
+    case TLS_ST_SW_ENCRYPTED_EXTENSIONS:
+        *confunc = tls_construct_encrypted_extensions;
+        *mt = SSL3_MT_ENCRYPTED_EXTENSIONS;
+        break;
     }
 
     return 1;
@@ -1052,6 +1062,71 @@ int dtls_construct_hello_verify_request(SSL *s, WPACKET *pkt)
     return 1;
 }
 
+#ifndef OPENSSL_NO_EC
+/*-
+ * ssl_check_for_safari attempts to fingerprint Safari using OS X
+ * SecureTransport using the TLS extension block in |hello|.
+ * Safari, since 10.6, sends exactly these extensions, in this order:
+ *   SNI,
+ *   elliptic_curves
+ *   ec_point_formats
+ *
+ * We wish to fingerprint Safari because they broke ECDHE-ECDSA support in 10.8,
+ * but they advertise support. So enabling ECDHE-ECDSA ciphers breaks them.
+ * Sadly we cannot differentiate 10.6, 10.7 and 10.8.4 (which work), from
+ * 10.8..10.8.3 (which don't work).
+ */
+static void ssl_check_for_safari(SSL *s, const CLIENTHELLO_MSG *hello)
+{
+    unsigned int type;
+    PACKET sni, tmppkt;
+    size_t ext_len;
+
+    static const unsigned char kSafariExtensionsBlock[] = {
+        0x00, 0x0a,             /* elliptic_curves extension */
+        0x00, 0x08,             /* 8 bytes */
+        0x00, 0x06,             /* 6 bytes of curve ids */
+        0x00, 0x17,             /* P-256 */
+        0x00, 0x18,             /* P-384 */
+        0x00, 0x19,             /* P-521 */
+
+        0x00, 0x0b,             /* ec_point_formats */
+        0x00, 0x02,             /* 2 bytes */
+        0x01,                   /* 1 point format */
+        0x00,                   /* uncompressed */
+        /* The following is only present in TLS 1.2 */
+        0x00, 0x0d,             /* signature_algorithms */
+        0x00, 0x0c,             /* 12 bytes */
+        0x00, 0x0a,             /* 10 bytes */
+        0x05, 0x01,             /* SHA-384/RSA */
+        0x04, 0x01,             /* SHA-256/RSA */
+        0x02, 0x01,             /* SHA-1/RSA */
+        0x04, 0x03,             /* SHA-256/ECDSA */
+        0x02, 0x03,             /* SHA-1/ECDSA */
+    };
+
+    /* Length of the common prefix (first two extensions). */
+    static const size_t kSafariCommonExtensionsLength = 18;
+
+    tmppkt = hello->extensions;
+
+    if (!PACKET_forward(&tmppkt, 2)
+        || !PACKET_get_net_2(&tmppkt, &type)
+        || !PACKET_get_length_prefixed_2(&tmppkt, &sni)) {
+        return;
+    }
+
+    if (type != TLSEXT_TYPE_server_name)
+        return;
+
+    ext_len = TLS1_get_client_version(s) >= TLS1_2_VERSION ?
+        sizeof(kSafariExtensionsBlock) : kSafariCommonExtensionsLength;
+
+    s->s3->is_probably_safari = PACKET_equal(&tmppkt, kSafariExtensionsBlock,
+                                             ext_len);
+}
+#endif                          /* !OPENSSL_NO_EC */
+
 MSG_PROCESS_RETURN tls_process_client_hello(SSL *s, PACKET *pkt)
 {
     int i, al = SSL_AD_INTERNAL_ERROR;
@@ -1239,8 +1314,8 @@ MSG_PROCESS_RETURN tls_process_client_hello(SSL *s, PACKET *pkt)
 
     /* Preserve the raw extensions PACKET for later use */
     extensions = clienthello.extensions;
-    if (!tls_collect_extensions(&extensions, &clienthello.pre_proc_exts,
-                                  &clienthello.num_extensions, &al)) {
+    if (!tls_collect_extensions(s, &extensions, EXT_CLIENT_HELLO,
+                                &clienthello.pre_proc_exts, &al)) {
         /* SSLerr already been called */
         goto f_err;
     }
@@ -1325,9 +1400,9 @@ MSG_PROCESS_RETURN tls_process_client_hello(SSL *s, PACKET *pkt)
     s->hit = 0;
 
     /* We need to do this before getting the session */
-    if (!tls_check_client_ems_support(s, &clienthello)) {
-        /* Only fails if the extension is malformed */
-        al = SSL_AD_DECODE_ERROR;
+    if (!tls_parse_extension(s, TLSEXT_IDX_extended_master_secret,
+                             EXT_CLIENT_HELLO,
+                             clienthello.pre_proc_exts, &al)) {
         SSLerr(SSL_F_TLS_PROCESS_CLIENT_HELLO, SSL_R_CLIENTHELLO_TLSEXT);
         goto f_err;
     }
@@ -1424,10 +1499,16 @@ MSG_PROCESS_RETURN tls_process_client_hello(SSL *s, PACKET *pkt)
         goto f_err;
     }
 
+#ifndef OPENSSL_NO_EC
+    if (s->options & SSL_OP_SAFARI_ECDHE_ECDSA_BUG)
+        ssl_check_for_safari(s, &clienthello);
+#endif                          /* !OPENSSL_NO_EC */
+
     /* TLS extensions */
-    if (!ssl_parse_clienthello_tlsext(s, &clienthello)) {
+    if (!tls_parse_all_extensions(s, EXT_CLIENT_HELLO,
+                                  clienthello.pre_proc_exts, &al)) {
         SSLerr(SSL_F_TLS_PROCESS_CLIENT_HELLO, SSL_R_PARSE_TLSEXT);
-        goto err;
+        goto f_err;
     }
 
     /* Check we've got a key_share for TLSv1.3 */
@@ -1611,6 +1692,54 @@ MSG_PROCESS_RETURN tls_process_client_hello(SSL *s, PACKET *pkt)
     return MSG_PROCESS_ERROR;
 }
 
+/*
+ * Call the status request callback if needed. Upon success, returns 1.
+ * Upon failure, returns 0 and sets |al| to the appropriate fatal alert.
+ */
+static int tls_handle_status_request(SSL *s, int *al)
+{
+    s->tlsext_status_expected = 0;
+
+    /*
+     * If status request then ask callback what to do. Note: this must be
+     * called after servername callbacks in case the certificate has changed,
+     * and must be called after the cipher has been chosen because this may
+     * influence which certificate is sent
+     */
+    if ((s->tlsext_status_type != -1) && s->ctx && s->ctx->tlsext_status_cb) {
+        int ret;
+        CERT_PKEY *certpkey;
+        certpkey = ssl_get_server_send_pkey(s);
+        /* If no certificate can't return certificate status */
+        if (certpkey != NULL) {
+            /*
+             * Set current certificate to one we will use so SSL_get_certificate
+             * et al can pick it up.
+             */
+            s->cert->key = certpkey;
+            ret = s->ctx->tlsext_status_cb(s, s->ctx->tlsext_status_arg);
+            switch (ret) {
+                /* We don't want to send a status request response */
+            case SSL_TLSEXT_ERR_NOACK:
+                s->tlsext_status_expected = 0;
+                break;
+                /* status request response should be sent */
+            case SSL_TLSEXT_ERR_OK:
+                if (s->tlsext_ocsp_resp)
+                    s->tlsext_status_expected = 1;
+                break;
+                /* something bad happened */
+            case SSL_TLSEXT_ERR_ALERT_FATAL:
+            default:
+                *al = SSL_AD_INTERNAL_ERROR;
+                return 0;
+            }
+        }
+    }
+
+    return 1;
+}
+
 WORK_STATE tls_post_process_client_hello(SSL *s, WORK_STATE wst)
 {
     int al = SSL_AD_HANDSHAKE_FAILURE;
@@ -1644,8 +1773,10 @@ WORK_STATE tls_post_process_client_hello(SSL *s, WORK_STATE wst)
             s->s3->tmp.new_cipher = cipher;
             /* check whether we should disable session resumption */
             if (s->not_resumable_session_cb != NULL)
-                s->session->not_resumable = s->not_resumable_session_cb(s,
-                                                                        ((cipher->algorithm_mkey & (SSL_kDHE | SSL_kECDHE)) != 0));
+                s->session->not_resumable =
+                    s->not_resumable_session_cb(s, ((cipher->algorithm_mkey
+                                                    & (SSL_kDHE | SSL_kECDHE))
+                                                   != 0));
             if (s->session->not_resumable)
                 /* do not send a session ticket */
                 s->tlsext_ticket_expected = 0;
@@ -1673,13 +1804,14 @@ WORK_STATE tls_post_process_client_hello(SSL *s, WORK_STATE wst)
          * s->s3->tmp.new_cipher- the new cipher to use.
          */
 
-        /* Handles TLS extensions that we couldn't check earlier */
-        if (s->version >= SSL3_VERSION) {
-            if (!ssl_check_clienthello_tlsext_late(s, &al)) {
-                SSLerr(SSL_F_TLS_POST_PROCESS_CLIENT_HELLO,
-                       SSL_R_CLIENTHELLO_TLSEXT);
-                goto f_err;
-            }
+        /*
+         * Call status_request callback if needed. Has to be done after the
+         * certificate callbacks etc above.
+         */
+        if (!tls_handle_status_request(s, &al)) {
+            SSLerr(SSL_F_TLS_POST_PROCESS_CLIENT_HELLO,
+                   SSL_R_CLIENTHELLO_TLSEXT);
+            goto f_err;
         }
 
         wst = WORK_MORE_B;
@@ -1773,18 +1905,27 @@ int tls_construct_server_hello(SSL *s, WPACKET *pkt)
         compm = s->s3->tmp.new_compression->id;
 #endif
 
-    if (!WPACKET_sub_memcpy_u8(pkt, s->session->session_id, sl)
+    if ((!SSL_IS_TLS13(s)
+                && !WPACKET_sub_memcpy_u8(pkt, s->session->session_id, sl))
             || !s->method->put_cipher_by_char(s->s3->tmp.new_cipher, pkt, &len)
-            || !WPACKET_put_bytes_u8(pkt, compm)
-            || !ssl_prepare_serverhello_tlsext(s)
-            || !ssl_add_serverhello_tlsext(s, pkt, &al)) {
+            || (!SSL_IS_TLS13(s)
+                && !WPACKET_put_bytes_u8(pkt, compm))
+               /*
+                * TODO(TLS1.3): For now we add all 1.2 and 1.3 extensions. Later
+                * we will do this based on the actual protocol
+                */
+            || !tls_construct_extensions(s, pkt,
+                                         EXT_TLS1_2_SERVER_HELLO
+                                         | EXT_TLS1_3_SERVER_HELLO
+                                         | EXT_TLS1_3_ENCRYPTED_EXTENSIONS
+                                         | EXT_TLS1_3_CERTIFICATE, &al)) {
         SSLerr(SSL_F_TLS_CONSTRUCT_SERVER_HELLO, ERR_R_INTERNAL_ERROR);
         goto err;
     }
 
     return 1;
  err:
-    ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
+    ssl3_send_alert(s, SSL3_AL_FATAL, al);
     return 0;
 }
 
@@ -3352,6 +3493,18 @@ MSG_PROCESS_RETURN tls_process_next_proto(SSL *s, PACKET *pkt)
 }
 #endif
 
+static int tls_construct_encrypted_extensions(SSL *s, WPACKET *pkt)
+{
+    /* TODO(TLS1.3): Zero length encrypted extensions message for now */
+    if (!WPACKET_put_bytes_u16(pkt, 0)) {
+        SSLerr(SSL_F_TLS_CONSTRUCT_ENCRYPTED_EXTENSIONS, ERR_R_INTERNAL_ERROR);
+        ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
+        return 0;
+    }
+
+    return 1;
+}
+
 #define SSLV2_CIPHER_LEN    3
 
 STACK_OF(SSL_CIPHER) *ssl_bytes_to_cipher_list(SSL *s,