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fit: cipher: aes: allow to store the IV in the FIT image 

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@softathome.com>
This commit is contained in:
Philippe Reynes 2020-09-17 15:01:46 +02:00 committed by Tom Rini
parent 34ca77c1e1
commit a6982a6f76
4 changed files with 72 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/image.h
View File

@ -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,

6
include/u-boot/aes.h
View File

@ -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;
}

22
lib/aes/aes-encrypt.c
View File

@ -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",

61
tools/image-host.c
View File

@ -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);