spl: vboot: Verify content before using load_addr

When using verified-boot in the SPL, the FIT content must be verified before it can be used.

Currently the load_addr FIT property is read and used as input to memcpy before the property is verified.

---
 common/spl/spl_fit.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

index 2321ebb0dde..a35c6092cee 100644
@@ -244,6 +244,16 @@ static int spl_load_fit_image(struct spl_load_info *info, ulong sector,
 		src = (void *)data;
 	}
 
+#ifdef CONFIG_SPL_FIT_SIGNATURE
+	printf("## Checking hash(es) for Image %s ...\n",
+	       fit_get_name(fit, node, NULL));
+	ret = fit_image_verify_with_data(fit, node,
+					 (const void *)src, length);
+	printf("\n");
+	if (!ret)
+		return 1;
+#endif
+
 #ifdef CONFIG_SPL_FIT_IMAGE_POST_PROCESS
 	board_fit_image_post_process(&src, &length);
 #endif

@@ -269,16 +279,7 @@ static int spl_load_fit_image(struct spl_load_info *info, ulong sector,
 		image_info->entry_point = fdt_getprop_u32(fit, node, "entry");
 	}
 
-#ifdef CONFIG_SPL_FIT_SIGNATURE
-	printf("## Checking hash(es) for Image %s ...\n",
-	       fit_get_name(fit, node, NULL));
-	ret = fit_image_verify_with_data(fit, node,
-					 (const void *)load_addr, length);
-	printf("\n");
-	return !ret;
-#else
 	return 0;
-#endif
 }
 
 static int spl_fit_append_fdt(struct spl_image_info *spl_image,

2.13.5

2018-06-06 9:08 GMT+08:00 Teddy Reed <[email protected]>:

Thanks for taking a look Jun! I did not see any sandbox tests exercising the SPL/signature checking so I included 'RFC'. I know you are familiar with using the signature checking within the SPL, and you helped make it possible in the first place.

The three minor concerns I had when moving the validation earlier are:
(1) the signature was originally calculated on the potentially uncompressed version, but this seems unlikely; similarly (2) the post process board-specific methods can mutate the signed content; and (3) now using the src address means reading directly from storage / etc instead of potentially SRAM/DRAM.

For (1) see that line 256 was uncompressing the data before signature checking. Then the signature check was applied to the uncompressed region. To be clear I think this patch is the correct approach, and the signature check should apply to the compressed content.

For (2) see that line 248 is board-specific, I am assuming that can mutate the content. Thus the signature check should be placed before that call.

Thanks again!

Teddy Reed V