From 16fc57bcc4fb2cec17af716abd70de76f82e1f64 Mon Sep 17 00:00:00 2001
From: gabor-mezei-arm <gabor.mezei@arm.com>
Date: Mon, 27 Sep 2021 11:58:31 +0200
Subject: [PATCH] Move mbedtls_cf_size_mask_ge function to the constant-time
 module

Signed-off-by: gabor-mezei-arm <gabor.mezei@arm.com>
---
 library/constant_time.c | 16 ++++++++++++++++
 library/constant_time.h |  2 ++
 library/ssl_msg.c       | 16 ----------------
 3 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/library/constant_time.c b/library/constant_time.c
index 928b9b7fe..b53d06ba6 100644
--- a/library/constant_time.c
+++ b/library/constant_time.c
@@ -161,3 +161,19 @@ size_t mbedtls_cf_size_mask_lt( size_t x, size_t y )
 
     return( mask );
 }
+
+/*
+ * Constant-flow mask generation for "greater or equal" comparison:
+ * - if x >= y, return all bits 1, that is (size_t) -1
+ * - otherwise, return all bits 0, that is 0
+ *
+ * This function can be used to write constant-time code by replacing branches
+ * with bit operations using masks.
+ *
+ * This function is implemented without using comparison operators, as those
+ * might be translated to branches by some compilers on some platforms.
+ */
+size_t mbedtls_cf_size_mask_ge( size_t x, size_t y )
+{
+    return( ~mbedtls_cf_size_mask_lt( x, y ) );
+}
diff --git a/library/constant_time.h b/library/constant_time.h
index 0b759000a..8e8992d6f 100644
--- a/library/constant_time.h
+++ b/library/constant_time.h
@@ -35,3 +35,5 @@ unsigned mbedtls_cf_uint_mask( unsigned value );
 size_t mbedtls_cf_size_mask( size_t bit );
 
 size_t mbedtls_cf_size_mask_lt( size_t x, size_t y );
+
+size_t mbedtls_cf_size_mask_ge( size_t x, size_t y );
diff --git a/library/ssl_msg.c b/library/ssl_msg.c
index 94f263d00..fedaab78e 100644
--- a/library/ssl_msg.c
+++ b/library/ssl_msg.c
@@ -939,22 +939,6 @@ int mbedtls_ssl_encrypt_buf( mbedtls_ssl_context *ssl,
 }
 
 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_TLS_CBC)
-/*
- * Constant-flow mask generation for "greater or equal" comparison:
- * - if x >= y, return all bits 1, that is (size_t) -1
- * - otherwise, return all bits 0, that is 0
- *
- * This function can be used to write constant-time code by replacing branches
- * with bit operations using masks.
- *
- * This function is implemented without using comparison operators, as those
- * might be translated to branches by some compilers on some platforms.
- */
-static size_t mbedtls_cf_size_mask_ge( size_t x, size_t y )
-{
-    return( ~mbedtls_cf_size_mask_lt( x, y ) );
-}
-
 /*
  * Constant-flow boolean "equal" comparison:
  * return x == y