vboot2: Introduce vb2ex_hwcrypto API
This patch extends the vboot2 API by three callback functions that the
platform firmware may implement to offer hardware crypto engine support.
For now we only support this for hash algorithms, and we will only allow
it for firmware body hashes (not the keyblock or preamble which are too
small to matter execution-time-wise anyway). The API is similar to the
vb2api_*_hash() functions used to start body hashing in the first place,
but we still take this round trip through vboot to allow it to do
key/signature management and retain full control of the verification
process. We also add a new preamble flag to explicitly disable this
feature, so that we can later return to a solely software-based
verification path through a firmware update in case a hardware crypto
engine turns out to be insecure.
CQ-DEPEND=CL:236435
BRANCH=None
BUG=chrome-os-partner:32987
TEST='make runtests VBOOT2=1'. Manually booted on Pinky with and without
HW crypto support and with the preamble flag set to confirm expected
behavior. lib21/ parts untested except for compiling and new unit tests.
Change-Id: I17c7d02f392089875a5942a5aafcf6a657354863
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/236453
Reviewed-by: Randall Spangler <rspangler@chromium.org>
diff --git a/tests/vb20_api_tests.c b/tests/vb20_api_tests.c
index a7be957..fbde39d 100644
--- a/tests/vb20_api_tests.c
+++ b/tests/vb20_api_tests.c
@@ -30,6 +30,12 @@
/* Mocked function data */
+static enum {
+ HWCRYPTO_DISABLED,
+ HWCRYPTO_ENABLED,
+ HWCRYPTO_FORBIDDEN,
+} hwcrypto_state;
+
static int retval_vb2_load_fw_keyblock;
static int retval_vb2_load_fw_preamble;
static int retval_vb2_digest_finalize;
@@ -74,6 +80,10 @@
(cc.workbuf + sd->workbuf_preamble_offset);
pre->body_signature.data_size = mock_body_size;
pre->body_signature.sig_size = mock_sig_size;
+ if (hwcrypto_state == HWCRYPTO_FORBIDDEN)
+ pre->flags = VB2_FIRMWARE_PREAMBLE_DISALLOW_HWCRYPTO;
+ else
+ pre->flags = 0;
sd->workbuf_data_key_offset = cc.workbuf_used;
sd->workbuf_data_key_size = sizeof(*k) + 8;
@@ -117,13 +127,51 @@
return VB2_SUCCESS;
}
+int vb2ex_hwcrypto_digest_init(enum vb2_hash_algorithm hash_alg,
+ uint32_t data_size)
+{
+ switch (hwcrypto_state) {
+ case HWCRYPTO_DISABLED:
+ return VB2_ERROR_EX_HWCRYPTO_UNSUPPORTED;
+ case HWCRYPTO_ENABLED:
+ if (hash_alg != mock_hash_alg)
+ return VB2_ERROR_SHA_INIT_ALGORITHM;
+ else
+ return VB2_SUCCESS;
+ case HWCRYPTO_FORBIDDEN:
+ default:
+ return VB2_ERROR_UNKNOWN;
+ }
+}
+
+int vb2ex_hwcrypto_digest_extend(const uint8_t *buf,
+ uint32_t size)
+{
+ if (hwcrypto_state != HWCRYPTO_ENABLED)
+ return VB2_ERROR_UNKNOWN;
+
+ return VB2_SUCCESS;
+}
+
+int vb2ex_hwcrypto_digest_finalize(uint8_t *digest,
+ uint32_t digest_size)
+{
+ if (hwcrypto_state != HWCRYPTO_ENABLED)
+ return VB2_ERROR_UNKNOWN;
+
+ return retval_vb2_digest_finalize;
+}
+
int vb2_digest_init(struct vb2_digest_context *dc,
enum vb2_hash_algorithm hash_alg)
{
+ if (hwcrypto_state == HWCRYPTO_ENABLED)
+ return VB2_ERROR_UNKNOWN;
if (hash_alg != mock_hash_alg)
return VB2_ERROR_SHA_INIT_ALGORITHM;
dc->hash_alg = hash_alg;
+ dc->using_hwcrypto = 0;
return VB2_SUCCESS;
}
@@ -132,6 +180,8 @@
const uint8_t *buf,
uint32_t size)
{
+ if (hwcrypto_state == HWCRYPTO_ENABLED)
+ return VB2_ERROR_UNKNOWN;
if (dc->hash_alg != mock_hash_alg)
return VB2_ERROR_SHA_EXTEND_ALGORITHM;
@@ -142,6 +192,8 @@
uint8_t *digest,
uint32_t digest_size)
{
+ if (hwcrypto_state == HWCRYPTO_ENABLED)
+ return VB2_ERROR_UNKNOWN;
return retval_vb2_digest_finalize;
}
@@ -268,12 +320,14 @@
TEST_EQ(vb2api_extend_hash(&cc, mock_body, 0),
VB2_ERROR_API_EXTEND_HASH_SIZE, "hash extend empty");
- reset_common_data(FOR_EXTEND_HASH);
- dc = (struct vb2_digest_context *)
- (cc.workbuf + sd->workbuf_hash_offset);
- dc->hash_alg = mock_hash_alg + 1;
- TEST_EQ(vb2api_extend_hash(&cc, mock_body, mock_body_size),
- VB2_ERROR_SHA_EXTEND_ALGORITHM, "hash extend fail");
+ if (hwcrypto_state != HWCRYPTO_ENABLED) {
+ reset_common_data(FOR_EXTEND_HASH);
+ dc = (struct vb2_digest_context *)
+ (cc.workbuf + sd->workbuf_hash_offset);
+ dc->hash_alg = mock_hash_alg + 1;
+ TEST_EQ(vb2api_extend_hash(&cc, mock_body, mock_body_size),
+ VB2_ERROR_SHA_EXTEND_ALGORITHM, "hash extend fail");
+ }
}
static void check_hash_tests(void)
@@ -338,6 +392,21 @@
int main(int argc, char* argv[])
{
phase3_tests();
+
+ fprintf(stderr, "Running hash API tests without hwcrypto support...\n");
+ hwcrypto_state = HWCRYPTO_DISABLED;
+ init_hash_tests();
+ extend_hash_tests();
+ check_hash_tests();
+
+ fprintf(stderr, "Running hash API tests with hwcrypto support...\n");
+ hwcrypto_state = HWCRYPTO_ENABLED;
+ init_hash_tests();
+ extend_hash_tests();
+ check_hash_tests();
+
+ fprintf(stderr, "Running hash API tests with forbidden hwcrypto...\n");
+ hwcrypto_state = HWCRYPTO_FORBIDDEN;
init_hash_tests();
extend_hash_tests();
check_hash_tests();