Do digesting, and sometimes padding, in SW when HW doesnt.
The keymaster1 specification only requires HW modules to implement
SHA256 out of the list of keymaster1 digest modes. That would force
many keys to be software only, and would break legacy scenarios. This
change uses SoftKeymasterDevice to front keymaster modules that don't
implement the full suite of digests, quietly inserting KM_DIGEST_NONE
and KM_PAD_NONE into key generation/import requests when necessary, then
performing the digesting, and sometimes padding, in software, then
delegating crypto operations to the hardware.
This is only done for RSA and EC keys. Software digesting isn't
possible for HMAC or AES-GCM keys.
Note that this is not the complete fix for the bug. Some changes in
keystore are also required, coming in another CL.
Bug: 24873723
Change-Id: I740572eb11341fb0659085309da01d5cbcd3854d
diff --git a/keymaster0_engine.cpp b/keymaster0_engine.cpp
index 4af045a..995bc0b 100644
--- a/keymaster0_engine.cpp
+++ b/keymaster0_engine.cpp
@@ -36,53 +36,7 @@
namespace keymaster {
-// int Keymaster0Engine::rsa_index_ = -1;
-// int Keymaster0Engine::ec_key_index_ = -1;
Keymaster0Engine* Keymaster0Engine::instance_ = nullptr;
-const RSA_METHOD Keymaster0Engine::rsa_method_ = {
- .common =
- {
- 0, // references
- 1 // is_static
- },
- .app_data = nullptr,
- .init = nullptr,
- .finish = nullptr,
- .size = nullptr,
- .sign = nullptr,
- .verify = nullptr,
-
- .encrypt = nullptr,
- .sign_raw = nullptr,
- .decrypt = nullptr,
- .verify_raw = nullptr,
-
- .private_transform = Keymaster0Engine::rsa_private_transform,
-
- .mod_exp = nullptr,
- .bn_mod_exp = BN_mod_exp_mont,
-
- .flags = RSA_FLAG_OPAQUE,
-
- .keygen = nullptr,
- .multi_prime_keygen = nullptr,
- .supports_digest = nullptr,
-};
-
-const ECDSA_METHOD Keymaster0Engine::ecdsa_method_ = {
- .common =
- {
- 0, // references
- 1 // is_static
- },
- .app_data = nullptr,
- .init = nullptr,
- .finish = nullptr,
- .group_order_size = nullptr,
- .sign = Keymaster0Engine::ecdsa_sign,
- .verify = nullptr,
- .flags = ECDSA_FLAG_OPAQUE,
-};
Keymaster0Engine::Keymaster0Engine(const keymaster0_device_t* keymaster0_device)
: keymaster0_device_(keymaster0_device), engine_(ENGINE_new()), supports_ec_(false) {
@@ -94,10 +48,40 @@
ec_key_index_ = EC_KEY_get_ex_new_index(0 /* argl */, NULL /* argp */, NULL /* new_func */,
keyblob_dup, keyblob_free);
+ rsa_method_.common.references = 0;
+ rsa_method_.common.is_static = 1;
+ rsa_method_.app_data = nullptr;
+ rsa_method_.init = nullptr;
+ rsa_method_.finish = nullptr;
+ rsa_method_.size = nullptr;
+ rsa_method_.sign = nullptr;
+ rsa_method_.verify = nullptr;
+ rsa_method_.encrypt = nullptr;
+ rsa_method_.sign_raw = nullptr;
+ rsa_method_.decrypt = nullptr;
+ rsa_method_.verify_raw = nullptr;
+ rsa_method_.private_transform = Keymaster0Engine::rsa_private_transform;
+ rsa_method_.mod_exp = nullptr;
+ rsa_method_.bn_mod_exp = BN_mod_exp_mont;
+ rsa_method_.flags = RSA_FLAG_OPAQUE;
+ rsa_method_.keygen = nullptr;
+ rsa_method_.supports_digest = nullptr;
+
ENGINE_set_RSA_method(engine_, &rsa_method_, sizeof(rsa_method_));
if ((keymaster0_device_->flags & KEYMASTER_SUPPORTS_EC) != 0) {
supports_ec_ = true;
+
+ ecdsa_method_.common.references = 0;
+ ecdsa_method_.common.is_static = 1;
+ ecdsa_method_.app_data = nullptr;
+ ecdsa_method_.init = nullptr;
+ ecdsa_method_.finish = nullptr;
+ ecdsa_method_.group_order_size = nullptr;
+ ecdsa_method_.sign = Keymaster0Engine::ecdsa_sign;
+ ecdsa_method_.verify = nullptr;
+ ecdsa_method_.flags = ECDSA_FLAG_OPAQUE;
+
ENGINE_set_ECDSA_method(engine_, &ecdsa_method_, sizeof(ecdsa_method_));
}
}
@@ -347,17 +331,6 @@
return 1;
}
-static size_t ec_group_size_bits(EC_KEY* ec_key) {
- const EC_GROUP* group = EC_KEY_get0_group(ec_key);
- unique_ptr<BN_CTX, BN_CTX_Delete> bn_ctx(BN_CTX_new());
- unique_ptr<BIGNUM, BIGNUM_Delete> order(BN_new());
- if (!EC_GROUP_get_order(group, order.get(), bn_ctx.get())) {
- ALOGE("Failed to get EC group order");
- return 0;
- }
- return BN_num_bits(order.get());
-}
-
int Keymaster0Engine::EcdsaSign(const uint8_t* digest, size_t digest_len, uint8_t* sig,
unsigned int* sig_len, EC_KEY* ec_key) const {
const keymaster_key_blob_t* key_blob = EcKeyToBlob(ec_key);