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u-boot: fit: add support to decrypt fit with aes

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This commit add to u-boot the support to decrypt
fit image encrypted with aes. The FIT image contains
the key name and the IV name. Then u-boot look for
the key and IV in his device tree and decrypt images
before moving to the next stage.

Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>
This commit is contained in:
Philippe Reynes
2019-12-18 18:25:42 +01:00
committed by Tom Rini
parent 7298e42250
commit 4df3578119
8 changed files with 240 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

104
common/image-cipher.c
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@@ -24,6 +24,7 @@ struct cipher_algo cipher_algos[] = {
.calculate_type = EVP_aes_128_cbc,
#endif
.encrypt = image_aes_encrypt,
.decrypt = image_aes_decrypt,
.add_cipher_data = image_aes_add_cipher_data
},
{
@@ -34,6 +35,7 @@ struct cipher_algo cipher_algos[] = {
.calculate_type = EVP_aes_192_cbc,
#endif
.encrypt = image_aes_encrypt,
.decrypt = image_aes_decrypt,
.add_cipher_data = image_aes_add_cipher_data
},
{
@@ -44,6 +46,7 @@ struct cipher_algo cipher_algos[] = {
.calculate_type = EVP_aes_256_cbc,
#endif
.encrypt = image_aes_encrypt,
.decrypt = image_aes_decrypt,
.add_cipher_data = image_aes_add_cipher_data
}
};
@@ -61,3 +64,104 @@ struct cipher_algo *image_get_cipher_algo(const char *full_name)
return NULL;
}
static int fit_image_setup_decrypt(struct image_cipher_info *info,
const void *fit, int image_noffset,
int cipher_noffset)
{
const void *fdt = gd_fdt_blob();
const char *node_name;
char node_path[128];
int noffset;
char *algo_name;
int ret;
node_name = fit_get_name(fit, image_noffset, NULL);
if (!node_name) {
printf("Can't get node name\n");
return -1;
}
if (fit_image_cipher_get_algo(fit, cipher_noffset, &algo_name)) {
printf("Can't get algo name for cipher '%s' in image '%s'\n",
node_name, node_name);
return -1;
}
info->keyname = fdt_getprop(fit, cipher_noffset, "key-name-hint", NULL);
if (!info->keyname) {
printf("Can't get key name\n");
return -1;
}
info->ivname = fdt_getprop(fit, cipher_noffset, "iv-name-hint", NULL);
if (!info->ivname) {
printf("Can't get IV name\n");
return -1;
}
info->fit = fit;
info->node_noffset = image_noffset;
info->name = algo_name;
info->cipher = image_get_cipher_algo(algo_name);
if (!info->cipher) {
printf("Can't get cipher\n");
return -1;
}
ret = fit_image_get_data_size_unciphered(fit, image_noffset,
&info->size_unciphered);
if (ret) {
printf("Can't get size of unciphered data\n");
return -1;
}
/*
* Search the cipher node in the u-boot fdt
* the path should be: /cipher/key-<algo>-<key>-<iv>
*/
snprintf(node_path, sizeof(node_path), "/%s/key-%s-%s-%s",
FIT_CIPHER_NODENAME, algo_name, info->keyname, info->ivname);
noffset = fdt_path_offset(fdt, node_path);
if (noffset < 0) {
printf("Can't found cipher node offset\n");
return -1;
}
/* read key */
info->key = fdt_getprop(fdt, noffset, "key", NULL);
if (!info->key) {
printf("Can't get key in cipher node '%s'\n", node_path);
return -1;
}
/* read iv */
info->iv = fdt_getprop(fdt, noffset, "iv", NULL);
if (!info->iv) {
printf("Can't get IV in cipher node '%s'\n", node_path);
return -1;
}
return 0;
}
int fit_image_decrypt_data(const void *fit,
int image_noffset, int cipher_noffset,
const void *data_ciphered, size_t size_ciphered,
void **data_unciphered, size_t *size_unciphered)
{
struct image_cipher_info info;
int ret;
ret = fit_image_setup_decrypt(&info, fit, image_noffset,
cipher_noffset);
if (ret < 0)
goto out;
ret = info.cipher->decrypt(&info, data_ciphered, size_ciphered,
data_unciphered, size_unciphered);
out:
return ret;
}