Re: [PATCH 7/7] bbu: print and evaluate image Metadata

[Stefan Christ <s.christ@phytec.de>]

Hi Sascha,

> @@ -147,6 +218,8 @@ int barebox_update(struct bbu_data *data)
>  	if (!data->devicefile)
>  		data->devicefile = handler->devicefile;
>  
> +	bbu_check_metadata(data);
> +
>  	ret = handler->handler(handler, data);
>  	if (ret == -EINTR)
>  		printf("update aborted\n");

hmm. I think the code should be 

     ret = bbu_check_metadata(data);
     if (ret)
          return ret;

or something. Otherwise the verification of the compatible doesn't abort the
update process. The function bbu_check_metadata returns -EINVAL if the
compatible is wrong.

The user has still the option to use "-f" or "-l" to flash a new barebox image,
if the already running barebox has the wrong compatible for the device. I just
noticed these options while looking at your patches. The force level is quite a
nice implementation to gradually overwrite any safety locks.

Mit freundlichen Grüßen / Kind regards,
	Stefan Christ

On Tue, Mar 29, 2016 at 10:50:54AM +0200, Sascha Hauer wrote:
> With imd we can store metadata in barebox images. Let's use this
> information to further verify that the image that is to be flashed
> is the correct one. This patch extracts the device tree compatible
> from the image and compares it with the one from the currently
> running barebox. If it doesn't match the update is aborted with a
> warning.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> ---
>  common/bbu.c  | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/bbu.h |  1 +
>  2 files changed, 74 insertions(+)
> 
> diff --git a/common/bbu.c b/common/bbu.c
> index 68812a7..b49fbe6 100644
> --- a/common/bbu.c
> +++ b/common/bbu.c
> @@ -26,6 +26,7 @@
>  #include <fcntl.h>
>  #include <malloc.h>
>  #include <linux/stat.h>
> +#include <image-metadata.h>
>  
>  static LIST_HEAD(bbu_image_handlers);
>  
> @@ -125,6 +126,76 @@ bool barebox_update_handler_exists(struct bbu_data *data)
>  	return !bbu_find_handler(data->handler_name);
>  }
>  
> +static int bbu_check_of_compat(struct bbu_data *data)
> +{
> +	struct device_node *root_node;
> +	const char *machine, *str;
> +	int ret;
> +	struct imd_header *of_compat;
> +
> +	if (!IS_ENABLED(CONFIG_OFDEVICE) || !IS_ENABLED(CONFIG_IMD))
> +		return 0;
> +
> +	of_compat = imd_find_type(data->imd_data, IMD_TYPE_OF_COMPATIBLE);
> +	if (!of_compat)
> +		return 0;
> +
> +	root_node = of_get_root_node();
> +	if (!root_node)
> +		return 0;
> +
> +	str = imd_string_data(of_compat, 0);
> +
> +	if (of_machine_is_compatible(str)) {
> +		pr_info("Devicetree compatible \"%s\" matches current machine\n", str);
> +		return 0;
> +	}
> +
> +	ret = of_property_read_string(root_node, "compatible", &machine);
> +	if (ret)
> +		return 0;
> +
> +	if (!bbu_force(data, "machine is incompatible with \"%s\", have \"%s\"\n", str, machine))
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static int bbu_check_metadata(struct bbu_data *data)
> +{
> +	struct imd_header *imd;
> +	int ret;
> +	char *str;
> +
> +	if (!data->image)
> +		return 0;
> +
> +	data->imd_data = imd_get(data->image, data->len);
> +	if (IS_ERR(data->imd_data)) {
> +		data->imd_data = NULL;
> +		return 0;
> +	}
> +
> +	printf("Image Metadata:\n");
> +	imd_for_each(data->imd_data, imd) {
> +		uint32_t type = imd_read_type(imd);
> +
> +		if (!imd_is_string(type))
> +			continue;
> +
> +		str = imd_concat_strings(imd);
> +
> +		printf("  %s: %s\n", imd_type_to_name(type), str);
> +		free(str);
> +	}
> +
> +	ret = bbu_check_of_compat(data);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
>  /*
>   * do a barebox update with data from *data
>   */
> @@ -147,6 +218,8 @@ int barebox_update(struct bbu_data *data)
>  	if (!data->devicefile)
>  		data->devicefile = handler->devicefile;
>  
> +	bbu_check_metadata(data);
> +
>  	ret = handler->handler(handler, data);
>  	if (ret == -EINTR)
>  		printf("update aborted\n");
> diff --git a/include/bbu.h b/include/bbu.h
> index 0fe7a1a..701d7f6 100644
> --- a/include/bbu.h
> +++ b/include/bbu.h
> @@ -16,6 +16,7 @@ struct bbu_data {
>  	const char *devicefile;
>  	size_t len;
>  	const char *handler_name;
> +	struct imd_header *imd_data;
>  };
>  
>  struct bbu_handler {
> -- 
> 2.7.0
> 
> 
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