History log of /system/keymaster/symmetric_key.cpp
Revision Date Author Comments (<<< Hide modified files) (Show modified files >>>)
33ab0389e908b98702806c746e7babc0d46eb452 08-Jul-2015 Shawn Willden <swillden@google.com> Add support for KM_TAG_MIN_MAC_LENGTH.

HMAC and AES-GCM keys must be bound to a mininum MAC/tag length at
creation, and operations may not specify a length smaller than the
minimum, or provide a length smaller than the minimum during
verification.

Bug: 22337277
Change-Id: Id5ae2f4259045ba1418c28e9de8f4a47e67fd433
/system/keymaster/symmetric_key.cpp
0f906ec40f6ade7955c6b967ea522aade54ea2e4 20-Jun-2015 Shawn Willden <swillden@google.com> Add buffer wrap checks and disable throwing of std::bad_alloc.

Android is built with exceptions disabled, but "operator new" and
"operator new[]" still throw std::bad_alloc on failure rather than
returning new. In general this is a good thing, because it will cause
an immediate crash of the process rather than assigning a null pointer
which is probably not checked. But most memory allocations in Keymaster
are checked, because it's written to run in an environment where new
does *not* throw. This CL updates the code to explicitly use the
non-throwing new.

A handful of throwing news remain, but only in places where a crash on
failure is appropriate.

In addition, this CL also inserts buffer wrap checks in key locations
and changes the development-machine Makefile to build in 32-bit mode, to
make memory problems more apparent.

Bug: 21888473
Change-Id: I8ebc5ec12053e4f5274f6f57ce312abc10611cef
/system/keymaster/symmetric_key.cpp
0629810b145187575bc26c910dded0d24c64569d 26-May-2015 Shawn Willden <swillden@google.com> Another refactor, deleting AbstractFactoryRegistry.

I should have known better than to make these singletons to begin
with. Globals create problems. This undoes that mistake.

Change-Id: Idf61d5f72e3c34b5c4ddb27cc94b05f506561743
/system/keymaster/symmetric_key.cpp
0cb6942d3efb6c056f96321c82a4b3d86af601d6 26-May-2015 Shawn Willden <swillden@google.com> Revert "Revert "Large refactor to move context out of AndroidKeymaster.""

This reverts commit 13fbe3e93247943c26e7ca2ed27b6d650282b8bf.

Bug: 20912868, 19799085
Change-Id: Iadd6ce5cbe94956c2a2fe277f1bf5b108e4bcf57
/system/keymaster/symmetric_key.cpp
13fbe3e93247943c26e7ca2ed27b6d650282b8bf 23-May-2015 Shawn Willden <swillden@google.com> Revert "Large refactor to move context out of AndroidKeymaster."

This reverts commit 8ba2a043f0d44ad3f58d4af518f9391c03eca9c3.

I need to update the Volantis non-secure code in sync. Reverting while I get that done.

Change-Id: I0fb9f928e7e624ad678050a04bb873b43b1c9a48
/system/keymaster/symmetric_key.cpp
8ba2a043f0d44ad3f58d4af518f9391c03eca9c3 18-May-2015 Shawn Willden <swillden@google.com> Large refactor to move context out of AndroidKeymaster.

AndroidKeymaster made a number of assumptions about its context that are
really only valid for TEE-based usage. In addition, KeyFactory made
some similarly TEE-focused assumptions about key blob creation and
parsing.

Both concerns have been moved to a new KeymasterContext class, which is
responsible for building and parsing key blobs in a manner appropriate
for the context in which AndroidKeymaster is running, as well as
providing other context-specific services, such as random number
generation.

In addition, the refactor reduces the need for the KeyBlob and
UnencryptedKeyBlob classes, which encode too many assumptions about blob
formatting and encryption, to the point that they can be removed and
replaced by a handful of utility functions which are much cleaner and
more flexible.

How to review this CL:

I looked hard at breaking this up into smaller CLs, but it's mostly not
feasible. However, it's probably easier to approach it by starting with
the fundamental changes, and then looking at the cascade effects.

1. Look at keymaster_context.h. The core of the change was pulling this
set of features out of AndroidKeymaster. Note that the revised approach
to key blob creation does not involve the KeyBlob and UnencryptedKeyBlob
classes, but instead goes directly from raw key material plus ancillary
data (e.g. auth sets) to a serialized buffer ready to return to
keystore. The same is true in reverse direction for parsing key blobs.

2. Look at key.h. The revised KeyFactory GenerateKey, ImportKey and
LoadKey methods are essential. GenerateKey and ImportKey no longer
produce a Key object, because all that's needed is a returnable blob.
LoadKey produces a Key object, but it starts with raw key material,
rather than an UnencryptedKeyBlob. Also note the change to the Key
class; because Key objects are only created by LoadKey, when there's a
need to use a key, there's only one constructor.

3. Look at asymmetric_key.h, rsa_key.h and rsa_key.cpp. rsa_key.cpp
provides a good example of how the new structure works. GenerateKey and
ImportKey do all of the work necessary to produce an OpenSSL RSA key and
extract the internal representation (using EvpToKeyMaterial; defined in
asymmetric_key.h because it's the same for EC keys). Then, with the raw
key data in hand, they call KeymasterContext::CreateKeyBlob to wrap the
key data in a key blob that can be returned to the caller -- whatever
that wrapping means in the current context. There's a subtlety not
apparent here which is crucial to the rationale for the refactoring:
RsaKeyFactory uses KeymasterContext::get_instance to retrieve the
context, but key factories which depend on operating in a particular
context can use a different way to get their context object, which may
have a larger interface. RsaKeymaster0KeyFactory will do this.

4. Look at soft_keymaster_context. In
particular, SoftKeymasterContext::CreateKeyBlob and ParseKeyBlob.
CreateKeyBlob allocates authorization tags from key_description to
hw_enforced and sw_enforced, then encrypts the key material and
serializes it to a blob. This approach is compatible with the keys
softkeymaster has been producing, but I'm going to change it (post M),
because there's no reason to bother encrypting SW keys with a SW key.
ParseKeyBlob reverses the process to recover the unencrypted key
material and the auth lists. One debatable point was the decision to
implement BuildHiddenAuthorizations and SetAuthorizations here, since
all contexts will need something similar, and they really should all do
it the same. I may refactor later to pull that functionality up to
KeymasterContext; it will depend on what I learn implementing
TrustyKeymasterContext and HybridKeymasterContext (used for the
keymaster0 adapter).

5. Look at ocb_utils and auth_encrypted_key_blob. These contain the key
encryption and key blob serialization code which was formerly split
between AndroidKeymaster::SerializeKeyBlob, UnencryptedKeyBlob and
KeyBlob, now divided into separate encryption and serialization
utilities. Note the refactored key_blob_test.cpp, updated to use the
new utilities rather than UnencryptedKeyBlob.

6. Look at soft_keymaster_device.cpp. Since KeyBlob no longer exists to
provide a nice way to peer into a blob to extract the algorithm, for use
in determining how to parse the keymaster0 signing key params (which
come in as a void*, yuck), we now have to use get_key_characteristics to
recover the params. This was the right way all along; the device layer
should not depend on being able to parse key blobs.

7. The rest.

Bug: 20912868, 19799085
Change-Id: Ieb74b8da39974f674eb8baa959bde75011fdd2e8
/system/keymaster/symmetric_key.cpp
125e4866f98eb1b5ad65a563afd34aca215d983d 11-May-2015 Shawn Willden <swillden@google.com> Remove rescoping support.

Change-Id: Ia8e36e41e04f15befccbb7b4138f599849facd28
(cherry picked from commit 0c14b2c5f42abdab58118106d5a7117a88d4a324)
/system/keymaster/symmetric_key.cpp
344549836442988693f27be8252c31bd2ebefdee 30-Apr-2015 Shawn Willden <swillden@google.com> Modify RAND_bytes calls to handle -1 return code.

Bug: 20554394
Change-Id: I54dce88f7bb90bd5660e9d3a7be9b9646bcc12bd
(cherry picked from commit 9ee79fb55049c242b12e067df1a824f18622ccfd)
/system/keymaster/symmetric_key.cpp
f01329d8692edde9a9ffb88f29f5d684eab481e2 12-Mar-2015 Shawn Willden <swillden@google.com> Improve error reporting and logging.

Bug: 19603049
Bug: 19509317
Change-Id: I041c973802e6c567adc5b1f280fc5bac27ba28d6
/system/keymaster/symmetric_key.cpp
5fad785a94716e4b71d51dcf2434ec09ff447b27 27-Jan-2015 Shawn Willden <swillden@google.com> Add initial support for rescoping.

This code does not yet validate that rescoping is authorized. A future
CL will integrate rescoping enforcement.

Change-Id: Iff66860630eef717562bce7c534a09d80b85a7a3
/system/keymaster/symmetric_key.cpp
7dad93b6552a2253ad6e7a493ddf0c9113806712 05-Feb-2015 Shawn Willden <swillden@google.com> Implement symmetric key import.

Change-Id: I902933c06c74c7b3b434873f53fb2c767d3b9721
/system/keymaster/symmetric_key.cpp
567a4a04f43d35b785d50508e6459b01f2ab4d14 31-Dec-2014 Shawn Willden <swillden@google.com> Switch to using global logger

Change-Id: I7af02342320a9a431cd9845baaf5dbcf61d460c2
/system/keymaster/symmetric_key.cpp
a278f6156b9e57e1de8ca380b14fef113ad10be8 23-Dec-2014 Shawn Willden <swillden@google.com> Refactor key creation to use a registry of key factories.

Change-Id: I6ebab7b44e4a5dbea282397ab8aca437e71bdca0
/system/keymaster/symmetric_key.cpp
0d560bfedd40389387f31f6696660fff6bc3a48a 16-Dec-2014 Shawn Willden <swillden@google.com> Add HMAC-SHA256 support.

Change-Id: I64c7bdf77388e3cb491b702c52c6746d32f317b0
/system/keymaster/symmetric_key.cpp
95e1382b75bab7d8b4cce3c1267fa23df2006957 16-Dec-2014 Shawn Willden <swillden@google.com> Refactor AesKey, extracting most functionality to SymmetricKey.

Symmetric key material handling is the same for all symmetric keys
(except, perhaps, DES if we want to handle parity bits correctly), so
move it into a common base.

Change-Id: I6ad5d35ce9020c1ae155bf0a8f2efe35674b1604
/system/keymaster/symmetric_key.cpp