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/*
* Copyright (C) 2023 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.
*/
//! Utility functions used by API tests.
use anyhow::{anyhow, Result};
use avb_bindgen::{
avb_footer_validate_and_byteswap, avb_vbmeta_image_header_to_host_byte_order, AvbFooter,
AvbVBMetaImageHeader,
};
use openssl::sha;
use pvmfw_avb::{
verify_payload, Capability, DebugLevel, Digest, PvmfwVerifyError, VerifiedBootData,
};
use std::{
fs,
mem::{size_of, transmute, MaybeUninit},
};
const MICRODROID_KERNEL_IMG_PATH: &str = "microdroid_kernel";
const INITRD_NORMAL_IMG_PATH: &str = "microdroid_initrd_normal.img";
const INITRD_DEBUG_IMG_PATH: &str = "microdroid_initrd_debuggable.img";
const PUBLIC_KEY_RSA4096_PATH: &str = "data/testkey_rsa4096_pub.bin";
pub const PUBLIC_KEY_RSA2048_PATH: &str = "data/testkey_rsa2048_pub.bin";
pub fn assert_payload_verification_with_initrd_fails(
kernel: &[u8],
initrd: &[u8],
trusted_public_key: &[u8],
expected_error: PvmfwVerifyError,
) -> Result<()> {
assert_payload_verification_fails(kernel, Some(initrd), trusted_public_key, expected_error)
}
pub fn assert_payload_verification_fails(
kernel: &[u8],
initrd: Option<&[u8]>,
trusted_public_key: &[u8],
expected_error: PvmfwVerifyError,
) -> Result<()> {
assert_eq!(expected_error, verify_payload(kernel, initrd, trusted_public_key).unwrap_err());
Ok(())
}
pub fn load_latest_signed_kernel() -> Result<Vec<u8>> {
Ok(fs::read(MICRODROID_KERNEL_IMG_PATH)?)
}
pub fn load_latest_initrd_normal() -> Result<Vec<u8>> {
Ok(fs::read(INITRD_NORMAL_IMG_PATH)?)
}
pub fn load_latest_initrd_debug() -> Result<Vec<u8>> {
Ok(fs::read(INITRD_DEBUG_IMG_PATH)?)
}
pub fn load_trusted_public_key() -> Result<Vec<u8>> {
Ok(fs::read(PUBLIC_KEY_RSA4096_PATH)?)
}
pub fn get_avb_footer_offset(signed_kernel: &[u8]) -> Result<usize> {
let offset = signed_kernel.len().checked_sub(size_of::<AvbFooter>());
offset.ok_or_else(|| anyhow!("Kernel too small to be AVB-signed"))
}
pub fn extract_avb_footer(kernel: &[u8]) -> Result<AvbFooter> {
let footer_start = get_avb_footer_offset(kernel)?;
// SAFETY: The slice is the same size as the struct which only contains simple data types.
let mut footer = unsafe {
transmute::<[u8; size_of::<AvbFooter>()], AvbFooter>(kernel[footer_start..].try_into()?)
};
// SAFETY: The function updates the struct in-place.
unsafe {
avb_footer_validate_and_byteswap(&footer, &mut footer);
}
Ok(footer)
}
pub fn extract_vbmeta_header(kernel: &[u8], footer: &AvbFooter) -> Result<AvbVBMetaImageHeader> {
let vbmeta_offset: usize = footer.vbmeta_offset.try_into()?;
let vbmeta_size: usize = footer.vbmeta_size.try_into()?;
let vbmeta_src = &kernel[vbmeta_offset..(vbmeta_offset + vbmeta_size)];
// SAFETY: The latest kernel has a valid VBMeta header at the position specified in footer.
let vbmeta_header = unsafe {
let mut header = MaybeUninit::uninit();
let src = vbmeta_src.as_ptr() as *const _ as *const AvbVBMetaImageHeader;
avb_vbmeta_image_header_to_host_byte_order(src, header.as_mut_ptr());
header.assume_init()
};
Ok(vbmeta_header)
}
pub fn assert_latest_payload_verification_passes(
initrd: &[u8],
initrd_salt: &[u8],
expected_debug_level: DebugLevel,
) -> Result<()> {
let public_key = load_trusted_public_key()?;
let kernel = load_latest_signed_kernel()?;
let verified_boot_data = verify_payload(&kernel, Some(initrd), &public_key)
.map_err(|e| anyhow!("Verification failed. Error: {}", e))?;
let footer = extract_avb_footer(&kernel)?;
let kernel_digest =
hash(&[&hash(&[b"bootloader"]), &kernel[..usize::try_from(footer.original_image_size)?]]);
let capabilities =
if cfg!(llpvm_changes) { vec![Capability::SecretkeeperProtection] } else { vec![] };
let initrd_digest = Some(hash(&[&hash(&[initrd_salt]), initrd]));
let expected_boot_data = VerifiedBootData {
debug_level: expected_debug_level,
kernel_digest,
initrd_digest,
public_key: &public_key,
capabilities,
rollback_index: if cfg!(llpvm_changes) { 1 } else { 0 },
};
assert_eq!(expected_boot_data, verified_boot_data);
Ok(())
}
pub fn hash(inputs: &[&[u8]]) -> Digest {
let mut digester = sha::Sha256::new();
inputs.iter().for_each(|input| digester.update(input));
digester.finish()
}