pvmfw/avb/tests/api_test.rs

/*
 * Copyright (C) 2022 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

use anyhow::Result;
use avb_bindgen::AvbFooter;
use pvmfw_avb::{verify_payload, AvbSlotVerifyError};
use std::{fs, mem::size_of};

const MICRODROID_KERNEL_IMG_PATH: &str = "microdroid_kernel";
const INITRD_NORMAL_IMG_PATH: &str = "microdroid_initrd_normal.img";
const TEST_IMG_WITH_ONE_HASHDESC_PATH: &str = "test_image_with_one_hashdesc.img";
const UNSIGNED_TEST_IMG_PATH: &str = "unsigned_test.img";

const PUBLIC_KEY_RSA2048_PATH: &str = "data/testkey_rsa2048_pub.bin";
const PUBLIC_KEY_RSA4096_PATH: &str = "data/testkey_rsa4096_pub.bin";
const RANDOM_FOOTER_POS: usize = 30;

/// This test uses the Microdroid payload compiled on the fly to check that
/// the latest payload can be verified successfully.
#[test]
fn latest_valid_payload_passes_verification() -> Result<()> {
    let kernel = load_latest_signed_kernel()?;
    let initrd_normal = fs::read(INITRD_NORMAL_IMG_PATH)?;
    let public_key = fs::read(PUBLIC_KEY_RSA4096_PATH)?;

    assert_eq!(Ok(()), verify_payload(&kernel, Some(&initrd_normal[..]), &public_key));
    Ok(())
}

#[test]
fn payload_expecting_no_initrd_passes_verification_with_no_initrd() -> Result<()> {
    let kernel = fs::read(TEST_IMG_WITH_ONE_HASHDESC_PATH)?;
    let public_key = fs::read(PUBLIC_KEY_RSA4096_PATH)?;

    assert_eq!(Ok(()), verify_payload(&kernel, None, &public_key));
    Ok(())
}

// TODO(b/256148034): Test that kernel with two hashdesc and no initrd fails verification.
// e.g. payload_expecting_initrd_fails_verification_with_no_initrd

#[test]
fn payload_with_empty_public_key_fails_verification() -> Result<()> {
    assert_payload_verification_fails(
        &load_latest_signed_kernel()?,
        &load_latest_initrd_normal()?,
        /*trusted_public_key=*/ &[0u8; 0],
        AvbSlotVerifyError::PublicKeyRejected,
    )
}

#[test]
fn payload_with_an_invalid_public_key_fails_verification() -> Result<()> {
    assert_payload_verification_fails(
        &load_latest_signed_kernel()?,
        &load_latest_initrd_normal()?,
        /*trusted_public_key=*/ &[0u8; 512],
        AvbSlotVerifyError::PublicKeyRejected,
    )
}

#[test]
fn payload_with_a_different_valid_public_key_fails_verification() -> Result<()> {
    assert_payload_verification_fails(
        &load_latest_signed_kernel()?,
        &load_latest_initrd_normal()?,
        &fs::read(PUBLIC_KEY_RSA2048_PATH)?,
        AvbSlotVerifyError::PublicKeyRejected,
    )
}

#[test]
fn unsigned_kernel_fails_verification() -> Result<()> {
    assert_payload_verification_fails(
        &fs::read(UNSIGNED_TEST_IMG_PATH)?,
        &load_latest_initrd_normal()?,
        &fs::read(PUBLIC_KEY_RSA4096_PATH)?,
        AvbSlotVerifyError::Io,
    )
}

#[test]
fn tampered_kernel_fails_verification() -> Result<()> {
    let mut kernel = load_latest_signed_kernel()?;
    kernel[1] = !kernel[1]; // Flip the bits

    assert_payload_verification_fails(
        &kernel,
        &load_latest_initrd_normal()?,
        &fs::read(PUBLIC_KEY_RSA4096_PATH)?,
        AvbSlotVerifyError::Verification,
    )
}

#[test]
fn tampered_kernel_footer_fails_verification() -> Result<()> {
    let mut kernel = load_latest_signed_kernel()?;
    let avb_footer_index = kernel.len() - size_of::<AvbFooter>() + RANDOM_FOOTER_POS;
    kernel[avb_footer_index] = !kernel[avb_footer_index];

    assert_payload_verification_fails(
        &kernel,
        &load_latest_initrd_normal()?,
        &fs::read(PUBLIC_KEY_RSA4096_PATH)?,
        AvbSlotVerifyError::InvalidMetadata,
    )
}

fn assert_payload_verification_fails(
    kernel: &[u8],
    initrd: &[u8],
    trusted_public_key: &[u8],
    expected_error: AvbSlotVerifyError,
) -> Result<()> {
    assert_eq!(Err(expected_error), verify_payload(kernel, Some(initrd), trusted_public_key));
    Ok(())
}

fn load_latest_signed_kernel() -> Result<Vec<u8>> {
    Ok(fs::read(MICRODROID_KERNEL_IMG_PATH)?)
}

fn load_latest_initrd_normal() -> Result<Vec<u8>> {
    Ok(fs::read(INITRD_NORMAL_IMG_PATH)?)
}