[PATCH 1/2] fit: cipher: aes: allow to store the IV in the FIT image
Philippe Reynes
philippe.reynes at softathome.com
Thu Sep 17 15:01:46 CEST 2020
Binaries may be encrypted in a FIT image with AES. This
algo needs a key and an IV (Initialization Vector). The
IV is provided in a file (pointer by iv-name-hint in the
ITS file) when building the ITB file.
This commits adds provide an alternative way to manage
the IV. If the property iv-name-hint is not provided in
the ITS file, the tool mkimage will generate an random
IV and store it in the FIT image.
Signed-off-by: Philippe Reynes <philippe.reynes at softathome.com>
---
include/image.h | 2 +-
include/u-boot/aes.h | 6 +++--
lib/aes/aes-encrypt.c | 22 +++++++++++++++----
tools/image-host.c | 61 +++++++++++++++++++++++++++++++++++++++++----------
4 files changed, 72 insertions(+), 19 deletions(-)
diff --git a/include/image.h b/include/image.h
index 9a5a87d..10995b8 100644
--- a/include/image.h
+++ b/include/image.h
@@ -1463,7 +1463,7 @@ struct cipher_algo {
unsigned char **cipher, int *cipher_len);
int (*add_cipher_data)(struct image_cipher_info *info,
- void *keydest);
+ void *keydest, void *fit, int node_noffset);
int (*decrypt)(struct image_cipher_info *info,
const void *cipher, size_t cipher_len,
diff --git a/include/u-boot/aes.h b/include/u-boot/aes.h
index 3228104..acbc50b 100644
--- a/include/u-boot/aes.h
+++ b/include/u-boot/aes.h
@@ -13,7 +13,8 @@
int image_aes_encrypt(struct image_cipher_info *info,
const unsigned char *data, int size,
unsigned char **cipher, int *cipher_len);
-int image_aes_add_cipher_data(struct image_cipher_info *info, void *keydest);
+int image_aes_add_cipher_data(struct image_cipher_info *info, void *keydest,
+ void *fit, int node_noffset);
#else
int image_aes_encrypt(struct image_cipher_info *info,
const unsigned char *data, int size,
@@ -22,7 +23,8 @@ int image_aes_encrypt(struct image_cipher_info *info,
return -ENXIO;
}
-int image_aes_add_cipher_data(struct image_cipher_info *info, void *keydest)
+int image_aes_add_cipher_data(struct image_cipher_info *info, void *keydest,
+ void *fit, int node_noffset)
{
return -ENXIO;
}
diff --git a/lib/aes/aes-encrypt.c b/lib/aes/aes-encrypt.c
index de00a83..a6d1720 100644
--- a/lib/aes/aes-encrypt.c
+++ b/lib/aes/aes-encrypt.c
@@ -74,7 +74,8 @@ int image_aes_encrypt(struct image_cipher_info *info,
return ret;
}
-int image_aes_add_cipher_data(struct image_cipher_info *info, void *keydest)
+int image_aes_add_cipher_data(struct image_cipher_info *info, void *keydest,
+ void *fit, int node_noffset)
{
int parent, node;
char name[128];
@@ -97,8 +98,13 @@ int image_aes_add_cipher_data(struct image_cipher_info *info, void *keydest)
goto done;
/* Either create or overwrite the named key node */
- snprintf(name, sizeof(name), "key-%s-%s-%s",
- info->name, info->keyname, info->ivname);
+ if (info->ivname)
+ snprintf(name, sizeof(name), "key-%s-%s-%s",
+ info->name, info->keyname, info->ivname);
+ else
+ snprintf(name, sizeof(name), "key-%s-%s",
+ info->name, info->keyname);
+
node = fdt_subnode_offset(keydest, parent, name);
if (node == -FDT_ERR_NOTFOUND) {
node = fdt_add_subnode(keydest, parent, name);
@@ -116,9 +122,17 @@ int image_aes_add_cipher_data(struct image_cipher_info *info, void *keydest)
ret = node;
}
- if (!ret)
+ if (ret)
+ goto done;
+
+ if (info->ivname)
+ /* Store the IV in the u-boot device tree */
ret = fdt_setprop(keydest, node, "iv",
info->iv, info->cipher->iv_len);
+ else
+ /* Store the IV in the FIT image */
+ ret = fdt_setprop(fit, node_noffset, "iv",
+ info->iv, info->cipher->iv_len);
if (!ret)
ret = fdt_setprop(keydest, node, "key",
diff --git a/tools/image-host.c b/tools/image-host.c
index 3d52593..8886bef 100644
--- a/tools/image-host.c
+++ b/tools/image-host.c
@@ -320,6 +320,36 @@ err:
return ret;
}
+static int get_random_data(void *data, int size)
+{
+ unsigned char *tmp = data;
+ struct timespec date;
+ int i, ret = 0;
+
+ if (!tmp) {
+ printf("%s: pointer data is NULL\n", __func__);
+ ret = -1;
+ goto out;
+ }
+
+ ret = clock_gettime(CLOCK_MONOTONIC, &date);
+ if (ret < 0) {
+ printf("%s: clock_gettime has failed (err=%d, str=%s)\n",
+ __func__, ret, strerror(ret));
+ goto out;
+ }
+
+ srand(date.tv_nsec);
+
+ for (i = 0; i < size; i++) {
+ *tmp = rand() & 0xff;
+ tmp++;
+ }
+
+ out:
+ return ret;
+}
+
static int fit_image_setup_cipher(struct image_cipher_info *info,
const char *keydir, void *fit,
const char *image_name, int image_noffset,
@@ -345,13 +375,13 @@ static int fit_image_setup_cipher(struct image_cipher_info *info,
goto out;
}
- /* Read the IV name */
+ /*
+ * Read the IV name
+ *
+ * If this property is not provided then mkimage will generate
+ * a random IV and store it in the FIT image
+ */
info->ivname = fdt_getprop(fit, noffset, "iv-name-hint", NULL);
- if (!info->ivname) {
- printf("Can't get iv name for cipher in image '%s'\n",
- image_name);
- goto out;
- }
info->fit = fit;
info->node_noffset = noffset;
@@ -377,17 +407,23 @@ static int fit_image_setup_cipher(struct image_cipher_info *info,
if (ret < 0)
goto out;
- /* Read the IV in the file */
- snprintf(filename, sizeof(filename), "%s/%s%s",
- info->keydir, info->ivname, ".bin");
info->iv = malloc(info->cipher->iv_len);
if (!info->iv) {
printf("Can't allocate memory for iv\n");
ret = -1;
goto out;
}
- ret = fit_image_read_data(filename, (unsigned char *)info->iv,
- info->cipher->iv_len);
+
+ if (info->ivname) {
+ /* Read the IV in the file */
+ snprintf(filename, sizeof(filename), "%s/%s%s",
+ info->keydir, info->ivname, ".bin");
+ ret = fit_image_read_data(filename, (unsigned char *)info->iv,
+ info->cipher->iv_len);
+ } else {
+ /* Generate an ramdom IV */
+ ret = get_random_data((void *)info->iv, info->cipher->iv_len);
+ }
out:
return ret;
@@ -453,9 +489,10 @@ fit_image_process_cipher(const char *keydir, void *keydest, void *fit,
* Write the public key into the supplied FDT file; this might fail
* several times, since we try signing with successively increasing
* size values
+ * And, if needed, write the iv in the FIT file
*/
if (keydest) {
- ret = info.cipher->add_cipher_data(&info, keydest);
+ ret = info.cipher->add_cipher_data(&info, keydest, fit, node_noffset);
if (ret) {
printf("Failed to add verification data for cipher '%s' in image '%s'\n",
info.keyname, image_name);
--
2.7.4
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