[tls] Use ANS X9.82 Approved RBG as source of random data for TLS

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

diff --git a/src/net/tls.c b/src/net/tls.c
index ace719c1151b98f2636e15402e3621ecb5a1188b..9acc5c3dc489f8c3fb86f3b7fc863ecae718e4b6 100644 (file)
--- a/src/net/tls.c
+++ b/src/net/tls.c
@@ -40,6 +40,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #include <ipxe/open.h>
 #include <ipxe/asn1.h>
 #include <ipxe/x509.h>
+#include <ipxe/rbg.h>
 #include <ipxe/tls.h>
 
 static int tls_send_plaintext ( struct tls_session *tls, unsigned int type,
@@ -121,12 +122,25 @@ static void tls_close ( struct tls_session *tls, int rc ) {
 /**
  * Generate random data
  *
+ * @v tls              TLS session
  * @v data             Buffer to fill
  * @v len              Length of buffer
+ * @ret rc             Return status code
  */
-static void tls_generate_random ( void *data, size_t len ) {
-       /* FIXME: Some real random data source would be nice... */
-       memset ( data, 0x01, len );
+static int tls_generate_random ( struct tls_session *tls,
+                                void *data, size_t len ) {
+       int rc;
+
+       /* Generate random bits with no additional input and without
+        * prediction resistance
+        */
+       if ( ( rc = rbg_generate ( NULL, 0, 0, data, len ) ) != 0 ) {
+               DBGC ( tls, "TLS %p could not generate random data: %s\n",
+                      tls, strerror ( rc ) );
+               return rc;
+       }
+
+       return 0;
 }
 
 /**
@@ -1782,11 +1796,14 @@ static struct process_descriptor tls_process_desc =
 
 int add_tls ( struct interface *xfer, struct interface **next ) {
        struct tls_session *tls;
+       int rc;
 
        /* Allocate and initialise TLS structure */
        tls = malloc ( sizeof ( *tls ) );
-       if ( ! tls )
-               return -ENOMEM;
+       if ( ! tls ) {
+               rc = -ENOMEM;
+               goto err_alloc;
+       }
        memset ( tls, 0, sizeof ( *tls ) );
        ref_init ( &tls->refcnt, free_tls );
        intf_init ( &tls->plainstream, &tls_plainstream_desc, &tls->refcnt );
@@ -1796,11 +1813,15 @@ int add_tls ( struct interface *xfer, struct interface **next ) {
        tls_clear_cipher ( tls, &tls->rx_cipherspec );
        tls_clear_cipher ( tls, &tls->rx_cipherspec_pending );
        tls->client_random.gmt_unix_time = 0;
-       tls_generate_random ( &tls->client_random.random,
-                             ( sizeof ( tls->client_random.random ) ) );
+       if ( ( rc = tls_generate_random ( tls, &tls->client_random.random,
+                         ( sizeof ( tls->client_random.random ) ) ) ) != 0 ) {
+               goto err_random;
+       }
        tls->pre_master_secret.version = htons ( TLS_VERSION_TLS_1_0 );
-       tls_generate_random ( &tls->pre_master_secret.random,
-                             ( sizeof ( tls->pre_master_secret.random ) ) );
+       if ( ( rc = tls_generate_random ( tls, &tls->pre_master_secret.random,
+                     ( sizeof ( tls->pre_master_secret.random ) ) ) ) != 0 ) {
+               goto err_random;
+       }
        digest_init ( &md5_algorithm, tls->handshake_md5_ctx );
        digest_init ( &sha1_algorithm, tls->handshake_sha1_ctx );
        process_init_stopped ( &tls->process, &tls_process_desc, &tls->refcnt );
@@ -1811,4 +1832,9 @@ int add_tls ( struct interface *xfer, struct interface **next ) {
        *next = &tls->cipherstream;
        ref_put ( &tls->refcnt );
        return 0;
+
+ err_random:
+       ref_put ( &tls->refcnt );
+ err_alloc:
+       return rc;
 }