[tls] Reject incorrect server names before completing validation

We currently verify the certificate name only after completing
validation of the certificate chain.  Perform this check instead at
the point of parsing the Certificate record, to create an invariant
that the recorded server certificate always has the correct name (even
if not yet validated).

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/net/tls.c b/src/net/tls.c
index 8e91f7a853aef6057c30f11c6e5160a11701fe8d..41111b522ba05a01e52267fe07930d9e7cea76e6 100644 (file)
--- a/src/net/tls.c
+++ b/src/net/tls.c
@@ -116,6 +116,10 @@ FILE_SECBOOT ( PERMITTED );
 #define EINFO_EIO_ALERT                                                        \
        __einfo_uniqify ( EINFO_EIO, 0x01,                              \
                          "Unknown alert level" )
+#define ENOENT_CERT __einfo_error ( EINFO_ENOENT_CERT )
+#define EINFO_ENOENT_CERT                                              \
+       __einfo_uniqify ( EINFO_ENOENT, 0x01,                           \
+                         "Missing server certificate" )
 #define ENOMEM_CONTEXT __einfo_error ( EINFO_ENOMEM_CONTEXT )
 #define EINFO_ENOMEM_CONTEXT                                           \
        __einfo_uniqify ( EINFO_ENOMEM, 0x01,                           \
@@ -2692,6 +2696,7 @@ static int tls_new_session_ticket ( struct tls_connection *tls,
  */
 static int tls_parse_chain ( struct tls_connection *tls,
                             const void *data, size_t len ) {
+       struct x509_certificate *cert;
        size_t remaining = len;
        int rc;
 
@@ -2721,7 +2726,6 @@ static int tls_parse_chain ( struct tls_connection *tls,
                } __attribute__ (( packed )) *certificate = data;
                size_t certificate_len;
                size_t record_len;
-               struct x509_certificate *cert;
 
                /* Parse header */
                if ( sizeof ( *certificate ) > remaining ) {
@@ -2757,8 +2761,25 @@ static int tls_parse_chain ( struct tls_connection *tls,
                remaining -= record_len;
        }
 
+       /* Identify server certificate */
+       cert = x509_first ( tls->server.chain );
+       if ( ! cert ) {
+               DBGC ( tls, "TLS %p certificate chain is empty\n", tls );
+               rc = -ENOENT_CERT;
+               goto err_empty;
+       }
+
+       /* Verify server name */
+       if ( ( rc = x509_check_name ( cert, tls->session->name ) ) != 0 ) {
+               DBGC ( tls, "TLS %p server certificate does not match %s: %s\n",
+                      tls, tls->session->name, strerror ( rc ) );
+               goto err_name;
+       }
+
        return 0;
 
+ err_name:
+ err_empty:
  err_parse:
  err_overlength:
  err_underlength:
@@ -4044,7 +4065,6 @@ static struct interface_descriptor tls_cipherstream_desc =
  * @v rc               Reason for completion
  */
 static void tls_validator_done ( struct tls_connection *tls, int rc ) {
-       struct tls_session *session = tls->session;
        struct x509_certificate *cert;
 
        /* Mark validation as complete */
@@ -4065,13 +4085,6 @@ static void tls_validator_done ( struct tls_connection *tls, int rc ) {
        cert = x509_first ( tls->server.chain );
        assert ( cert != NULL );
 
-       /* Verify server name */
-       if ( ( rc = x509_check_name ( cert, session->name ) ) != 0 ) {
-               DBGC ( tls, "TLS %p server certificate does not match %s: %s\n",
-                      tls, session->name, strerror ( rc ) );
-               goto err;
-       }
-
        /* Extract the now trusted server public key */
        tls->server.algorithm = cert->subject.public_key.algorithm;
        memcpy ( &tls->server.key, &cert->subject.public_key.raw,