commit bc07793ab2441f4950201bbffd98b3016b93806c
author Fabio Utzig <utzig@apache.org> Mon Aug 26 11:16:34 2019 -0300
committer Fabio Utzig <utzig@utzig.org> Mon Sep 09 10:00:09 2019 -0300
tree d43ea1f295a80ac4809e472d90d5ea7a4ad35896
parent 1e4284b358638792eacf2b777e5b4abb3df177a6

Add macro to check if image must be decrypted

An image must be decrypted when it is loaded on the secondary slot and
its header flag indicates it is encrypted. Instead of checking both
things every time the image is read, add a new macro, MUST_DECRYPT, that
does both checks.

Also `BOOT_CURR_ENC` was simplified to be used directly on
`bootutil_img_validate` calls, returning NULL for no encrypted images.

Signed-off-by: Fabio Utzig <utzig@apache.org>

boot/bootutil/src/loader.c

diff --git a/boot/bootutil/src/loader.c b/boot/bootutil/src/loader.c
index 0685cbb..43a6955 100644
--- a/boot/bootutil/src/loader.c
+++ b/boot/bootutil/src/loader.c
@@ -771,18 +771,13 @@
     (void)state;
 #endif
 
-    image_index = BOOT_CURR_IMG(state);
-
-#ifndef MCUBOOT_ENC_IMAGES
     (void)bs;
     (void)rc;
-    if (bootutil_img_validate(NULL, image_index, hdr, fap, tmpbuf,
-                              BOOT_TMPBUF_SZ, NULL, 0, NULL)) {
-        return BOOT_EBADIMAGE;
-    }
-#else
-    if ((fap->fa_id == FLASH_AREA_IMAGE_SECONDARY(image_index))
-            && IS_ENCRYPTED(hdr)) {
+
+    image_index = BOOT_CURR_IMG(state);
+
+#ifdef MCUBOOT_ENC_IMAGES
+    if (MUST_DECRYPT(fap, image_index, hdr)) {
         rc = boot_enc_load(BOOT_CURR_ENC(state), image_index, hdr, fap, bs->enckey[1]);
         if (rc < 0) {
             return BOOT_EBADIMAGE;
@@ -791,11 +786,12 @@
             return BOOT_EBADIMAGE;
         }
     }
+#endif
+
     if (bootutil_img_validate(BOOT_CURR_ENC(state), image_index, hdr, fap, tmpbuf,
                               BOOT_TMPBUF_SZ, NULL, 0, NULL)) {
         return BOOT_EBADIMAGE;
     }
-#endif
 
     return 0;
 }