hardware_interfaces/security/keymint/support/fuzzer

Fuzzers for libkeymint_support

Plugin Design Considerations

The fuzzer plugins for libkeymint_support are designed based on the understanding of the source code and try to achieve the following:

Maximize code coverage

The configuration parameters are not hardcoded, but instead selected based on incoming data. This ensures more code paths are reached by the fuzzers.

Maximize utilization of input data

The plugins feed the entire input data to the module. This ensures that the plugins tolerate any kind of input (empty, huge, malformed, etc) and dont exit() on any input and thereby increasing the chance of identifying vulnerabilities.

Table of contents

• keymint_attestation_fuzzer
• keymint_authSet_fuzzer

Fuzzer for KeyMintAttestation

KeyMintAttestation supports the following parameters:

1. PaddingMode(parameter name: "padding")
2. Digest(parameter name: "digest")
3. Index(parameter name: "idx")
4. Timestamp(parameter name: "timestamp")
5. AuthSet(parameter name: "authSet")
6. IssuerSubjectName(parameter name: "issuerSubjectName")
7. AttestationChallenge(parameter name: "challenge")
8. AttestationApplicationId(parameter name: "id")
9. EcCurve(parameter name: "ecCurve")
10. BlockMode(parameter name: "blockmode")
11. minMacLength(parameter name: "minMacLength")
12. macLength(parameter name: "macLength")

Parameter	Valid Values	Configured Value
padding	PaddingMode	Value obtained from FuzzedDataProvider
digest	Digest	Value obtained from FuzzedDataProvider
idx	size_t	Value obtained from FuzzedDataProvider
timestamp	uint64_t	Value obtained from FuzzedDataProvider
authSet	uint32_t	Value obtained from FuzzedDataProvider
issuerSubjectName	uint8_t	Value obtained from FuzzedDataProvider
AttestationChallenge	string	Value obtained from FuzzedDataProvider
AttestationApplicationId	string	Value obtained from FuzzedDataProvider
blockmode	BlockMode	Value obtained from FuzzedDataProvider
minMacLength	uint32_t	Value obtained from FuzzedDataProvider
macLength	uint32_t	Value obtained from FuzzedDataProvider

Steps to run

1. Build the fuzzer

$ mm -j$(nproc) keymint_attestation_fuzzer

2. Run on device

$ adb sync data
$ adb shell /data/fuzz/arm64/keymint_attestation_fuzzer/keymint_attestation_fuzzer

Fuzzer for KeyMintAuthSet

KeyMintAuthSet supports the following parameters:

1. AuthorizationSet(parameter name: "authSet")
2. AuthorizationSet(parameter name: "params")
3. KeyParameters(parameter name: "numKeyParam")
4. Tag(parameter name: "tag")

Parameter	Valid Values	Configured Value
authSet	AuthorizationSet	Value obtained from FuzzedDataProvider
params	AuthorizationSet	Value obtained from FuzzedDataProvider
numKeyParam	size_t	Value obtained from FuzzedDataProvider
tag	Tag	Value obtained from FuzzedDataProvider

Steps to run

1. Build the fuzzer

$ mm -j$(nproc) keymint_authSet_fuzzer

2. Run on device

$ adb sync data
$ adb shell /data/fuzz/arm64/keymint_authSet_fuzzer/keymint_authSet_fuzzer