[U-Boot] [RFC PATCH 32/44] image: Support signing of images

Simon Glass
2013-01-05T01:52:01Z

Add support for signing images using a new signature node. The process
is handled by fdt_add_verification_data() which now takes parameters to
provide the keys and related information.

Signed-off-by: Simon Glass <sjg@chromium.org>
---
doc/uImage.FIT/sign-images.its | 42 +++++++++
include/image.h | 22 ++++-
tools/fit_image.c | 2 +-
tools/image-host.c | 181 +++++++++++++++++++++++++++++++++++++--
4 files changed, 232 insertions(+), 15 deletions(-)
create mode 100644 doc/uImage.FIT/sign-images.its

diff --git a/doc/uImage.FIT/sign-images.its b/doc/uImage.FIT/sign-images.its
new file mode 100644
index 0000000..f69326a
--- /dev/null
+++ b/doc/uImage.FIT/sign-images.its
@@ -0,0 +1,42 @@
+/dts-v1/;
+
+/ {
+ description = "Chrome OS kernel image with one or more FDT blobs";
+ #address-cells = <1>;
+
+ images {
+ kernel at 1 {
+ data = /incbin/("test-kernel.bin");
+ type = "kernel_noload";
+ arch = "sandbox";
+ os = "linux";
+ compression = "none";
+ load = <0x4>;
+ entry = <0x8>;
+ kernel-version = <1>;
+ signature at 1 {
+ algo = "sha1,rsa2048";
+ key-name-hint = "dev";
+ };
+ };
+ fdt at 1 {
+ description = "snow";
+ data = /incbin/("sandbox-kernel.dtb");
+ type = "flat_dt";
+ arch = "sandbox";
+ compression = "none";
+ fdt-version = <1>;
+ signature at 1 {
+ algo = "sha1,rsa2048";
+ key-name-hint = "dev";
+ };
+ };
+ };
+ configurations {
+ default = "conf at 1";
+ conf at 1 {
+ kernel = "kernel at 1";
+ fdt = "fdt at 1";
+ };
+ };
+};
diff --git a/include/image.h b/include/image.h
index 8c648dc..a1072c0 100644
--- a/include/image.h
+++ b/include/image.h
@@ -611,12 +611,26 @@ int fit_image_hash_get_ignore(const void *fit, int noffset, int *ignore);
int fit_set_timestamp(void *fit, int noffset, time_t timestamp);

/**
- * fit_add_verification_data() - Calculate and add hashes to FIT
+ * fit_add_verification_data() - add verification data to FIT image nodes
*
- * @fit: Fit image to process
- * @return 0 if ok, <0 for error
+ * @keydir: Directory containing keys
+ * @kwydest: FDT blob to write public key information to
+ * @fit: Pointer to the FIT format image header
+ * @comment: Comment to add to signature nodes
+ * @require_keys: Mark all keys as 'required'
+ *
+ * Adds hash values for all component images in the FIT blob.
+ * Hashes are calculated for all component images which have hash subnodes
+ * with algorithm property set to one of the supported hash algorithms.
+ *
+ * Also add signatures if signature nodes are present.
+ *
+ * returns
+ * 0, on success
+ * libfdt error code, on failure
*/
-int fit_add_verification_data(void *fit);
+int fit_add_verification_data(const char *keydir, void *keydest, void *fit,
+ const char *comment, int require_keys);

int fit_image_verify(const void *fit, int noffset);
int fit_all_image_verify(const void *fit);
diff --git a/tools/fit_image.c b/tools/fit_image.c
index 8f51159..e0675d7 100644
--- a/tools/fit_image.c
+++ b/tools/fit_image.c
@@ -125,7 +125,7 @@ static int fit_handle_file (struct mkimage_params *params)
}

/* set hashes for images in the blob */
- if (fit_add_verification_data(ptr)) {
+ if (fit_add_verification_data(NULL, NULL, ptr, NULL, 0)) {
fprintf (stderr, "%s Can't add hashes to FIT blob",
params->cmdname);
unlink (tmpfile);
diff --git a/tools/image-host.c b/tools/image-host.c
index 4c589af..4196190 100644
--- a/tools/image-host.c
+++ b/tools/image-host.c
@@ -26,12 +26,8 @@
*/

#include "mkimage.h"
-#include <bootstage.h>
#include <image.h>
-#include <sha1.h>
-#include <time.h>
-#include <u-boot/crc.h>
-#include <u-boot/md5.h>
+#include <version.h>

/**
* fit_set_hash_value - set hash value in requested has node
@@ -113,9 +109,161 @@ static int fit_image_process_hash(void *fit, const char *image_name,
}

/**
- * fit_image_add_verification_data() - calculate/set hash data for image node
+ * fit_image_write_sig() - write the signature to a FIT
*
- * This adds hash values for a component image node.
+ * This writes the signature and signer data to the FIT.
+ *
+ * @fit: pointer to the FIT format image header
+ * @noffset: hash node offset
+ * @value: signature value to be set
+ * @value_len: signature value length
+ * @comment: Text comment to write (NULL for none)
+ *
+ * returns
+ * 0, on success
+ * -1, on failure
+ */
+static int fit_image_write_sig(void *fit, int noffset, uint8_t *value,
+ int value_len, const char *comment, const char *region_prop,
+ int region_proplen)
+{
+ int string_size;
+ int ret;
+
+ /*
+ * Get the current string size, before we update the FIT and add
+ * more
+ */
+ string_size = fdt_size_dt_strings(fit);
+
+ ret = fdt_setprop(fit, noffset, FIT_VALUE_PROP, value, value_len);
+ ret |= fdt_setprop_string(fit, noffset, "signer-name", "mkimage");
+ ret |= fdt_setprop_string(fit, noffset, "signer-version",
+ PLAIN_VERSION);
+ if (comment)
+ ret |= fdt_setprop_string(fit, noffset, "comment", comment);
+ ret |= fit_set_timestamp(fit, noffset, time(NULL));
+ if (region_prop) {
+ uint32_t strdata[2];
+
+ ret |= fdt_setprop(fit, noffset, "hashed-nodes",
+ region_prop, region_proplen);
+ strdata[0] = 0;
+ strdata[1] = cpu_to_fdt32(string_size);
+ ret |= fdt_setprop(fit, noffset, "hashed-strings", strdata,
+ sizeof(strdata));
+ }
+
+ return ret;
+}
+
+static int fit_image_setup_sig(struct image_sign_info *info,
+ const char *keydir, void *fit, const char *image_name,
+ int noffset, const char *require_keys)
+{
+ const char *node_name;
+ char *algo_name;
+
+ node_name = fit_get_name(fit, noffset, NULL);
+ if (fit_image_hash_get_algo(fit, noffset, &algo_name)) {
+ printf("Can't get algo property for "
+ "'%s' signature node in '%s' image node\n",
+ node_name, image_name);
+ return -1;
+ }
+
+ memset(info, '\0', sizeof(*info));
+ info->keydir = keydir;
+ info->keyname = fdt_getprop(fit, noffset, "key-name-hint", NULL);
+ info->fit = fit;
+ info->node_offset = noffset;
+ info->algo = image_get_sig_algo(algo_name);
+ info->require_keys = require_keys;
+ if (!info->algo) {
+ printf("Unsupported signature algorithm (%s) for "
+ "'%s' signature node in '%s' image node\n",
+ algo_name, node_name, image_name);
+ return -1;
+ }
+
+ return 0;
+}
+
+/**
+ * fit_image_process_sig- Process a single subnode of the images/ node
+ *
+ * Check each subnode and process accordingly. For signature nodes we
+ * generate a signed hash of the supplised data and store it in the node.
+ *
+ * @keydir: Directory containing keys to use for signing
+ * @keydest: Destination FDT blob to write public keys into
+ * @fit: pointer to the FIT format image header
+ * @image_name: name of image being processes (used to display errors)
+ * @noffset: subnode offset
+ * @data: data to process
+ * @size: size of data in bytes
+ * @comment: Comment to add to signature nodes
+ * @require_keys: Mark all keys as 'required'
+ * @return 0 if ok, -1 on error
+ */
+static int fit_image_process_sig(const char *keydir, void *keydest,
+ void *fit, const char *image_name,
+ int noffset, const void *data, size_t size,
+ const char *comment, int require_keys)
+{
+ struct image_sign_info info;
+ struct image_region region;
+ const char *node_name;
+ uint8_t *value;
+ uint value_len;
+ int ret;
+
+ if (fit_image_setup_sig(&info, keydir, fit, image_name, noffset,
+ require_keys ? "image" : NULL))
+ return -1;
+
+ node_name = fit_get_name(fit, noffset, NULL);
+ region.data = data;
+ region.size = size;
+ ret = info.algo->sign(&info, &region, 1, &value, &value_len);
+ if (ret) {
+ printf("Failed to sign '%s' signature node in '%s'"
+ " image node: %d\n",
+ node_name, image_name, ret);
+
+ /* We allow keys to be missing */
+ if (ret == -ENOENT)
+ return 0;
+ return -1;
+ }
+
+ if (fit_image_write_sig(fit, noffset, value, value_len, comment,
+ NULL, 0)) {
+ printf("Can't write signature for "
+ "'%s' signature node in '%s' image node\n",
+ node_name, image_name);
+ return -1;
+ }
+ free(value);
+
+ /* Get keyname again, as FDT has changed and invalidated our pointer */
+ info.keyname = fdt_getprop(fit, noffset, "key-name-hint", NULL);
+
+ /* Write the public key into the supplied FDT file */
+ if (keydest && info.algo->add_verify_data(&info, keydest)) {
+ printf("Failed to add verification data for "
+ "'%s' signature node in '%s' image node\n",
+ node_name, image_name);
+ return -1;
+ }
+
+ return 0;
+}
+
+/**
+ * fit_image_add_verification_data() - calculate/set verig. data for image node
+ *
+ * This adds hash and signature values for an component image node.
*
* All existing hash subnodes are checked, if algorithm property is set to
* one of the supported hash algorithms, hash value is computed and
@@ -138,11 +286,17 @@ static int fit_image_process_hash(void *fit, const char *image_name,
*
* For signature details, please see doc/uImage.FIT/signature.txt
*
+ * @keydir Directory containing *.key and *.crt files (or NULL)
+ * @keydest FDT Blob to write public keys into (NULL if none)
* @fit: Pointer to the FIT format image header
* @image_noffset: Requested component image node
+ * @comment: Comment to add to signature nodes
+ * @require_keys: Mark all keys as 'required'
* @return: 0 on success, <0 on failure
*/
-int fit_image_add_verification_data(void *fit, int image_noffset)
+int fit_image_add_verification_data(const char *keydir, void *keydest,
+ void *fit, int image_noffset, const char *comment,
+ int require_keys)
{
const char *image_name;
const void *data;
@@ -176,6 +330,11 @@ int fit_image_add_verification_data(void *fit, int image_noffset)
strlen(FIT_HASH_NODENAME))) {
ret = fit_image_process_hash(fit, image_name, noffset,
data, size);
+ } else if (keydir && !strncmp(node_name, FIT_SIG_NODENAME,
+ strlen(FIT_SIG_NODENAME))) {
+ ret = fit_image_process_sig(keydir, keydest,
+ fit, image_name, noffset, data, size,
+ comment, require_keys);
}
if (ret)
return -1;
@@ -184,7 +343,8 @@ int fit_image_add_verification_data(void *fit, int image_noffset)
return 0;
}

-int fit_add_verification_data(void *fit)
+int fit_add_verification_data(const char *keydir, void *keydest, void *fit,
+ const char *comment, int require_keys)
{
int images_noffset;
int noffset;
@@ -209,7 +369,8 @@ int fit_add_verification_data(void *fit)
* Direct child node of the images parent node,
* i.e. component image node.
*/
- ret = fit_image_add_verification_data(fit, noffset);
+ ret = fit_image_add_verification_data(keydir, keydest,
+ fit, noffset, comment, require_keys);
if (ret)
return ret;
}
--
1.7.7.3