Improve APK signature handling
There are two changes here:
- The maxSdk property of a signature is inclusive not exclusive
(https://source.android.com/docs/security/features/apksigning/v3),
so our mapping to a Rust Range was wrong.
- We hard-wired the platform SDK as 31; but really we should use the
version of the platform we're running on.
I thought the APK Verify library shouldn't really be reading
properties, so instead I changed the function signatures to accept the
current SDK version as a parameter. That does mean duplicating the
code to read it in virtualization manager & microdroid manager, but I
can live with that for now.
Bug: 271500509
Bug: 190343842
Test: atest MicrodroidTests
Test: run a VM from an APK signed with minSdk = 33
Change-Id: I7ec7a201d05a6545847eb9b264abe642de883e0b
diff --git a/libs/apkverify/src/v3.rs b/libs/apkverify/src/v3.rs
index e1b728d..6082422 100644
--- a/libs/apkverify/src/v3.rs
+++ b/libs/apkverify/src/v3.rs
@@ -24,7 +24,7 @@
use openssl::x509::X509;
use std::fs::File;
use std::io::{Read, Seek};
-use std::ops::Range;
+use std::ops::RangeInclusive;
use std::path::Path;
use crate::algorithms::SignatureAlgorithmID;
@@ -33,11 +33,9 @@
pub const APK_SIGNATURE_SCHEME_V3_BLOCK_ID: u32 = 0xf05368c0;
-// TODO(b/190343842): get "ro.build.version.sdk"
-const SDK_INT: u32 = 31;
-
type Signers = LengthPrefixed<Vec<LengthPrefixed<Signer>>>;
+#[derive(Debug)]
pub(crate) struct Signer {
signed_data: LengthPrefixed<Bytes>, // not verified yet
min_sdk: u32,
@@ -47,8 +45,8 @@
}
impl Signer {
- fn sdk_range(&self) -> Range<u32> {
- self.min_sdk..self.max_sdk
+ fn sdk_range(&self) -> RangeInclusive<u32> {
+ self.min_sdk..=self.max_sdk
}
}
@@ -62,8 +60,8 @@
}
impl SignedData {
- fn sdk_range(&self) -> Range<u32> {
- self.min_sdk..self.max_sdk
+ fn sdk_range(&self) -> RangeInclusive<u32> {
+ self.min_sdk..=self.max_sdk
}
fn find_digest_by_algorithm(&self, algorithm_id: SignatureAlgorithmID) -> Result<&Digest> {
@@ -92,32 +90,30 @@
/// Verifies APK Signature Scheme v3 signatures of the provided APK and returns the public key
/// associated with the signer in DER format.
-pub fn verify<P: AsRef<Path>>(apk_path: P) -> Result<Box<[u8]>> {
+pub fn verify<P: AsRef<Path>>(apk_path: P, current_sdk: u32) -> Result<Box<[u8]>> {
let apk = File::open(apk_path.as_ref())?;
- let (signer, mut sections) = extract_signer_and_apk_sections(apk)?;
+ let (signer, mut sections) = extract_signer_and_apk_sections(apk, current_sdk)?;
signer.verify(&mut sections)
}
/// Gets the public key (in DER format) that was used to sign the given APK/APEX file
-pub fn get_public_key_der<P: AsRef<Path>>(apk_path: P) -> Result<Box<[u8]>> {
+pub fn get_public_key_der<P: AsRef<Path>>(apk_path: P, current_sdk: u32) -> Result<Box<[u8]>> {
let apk = File::open(apk_path.as_ref())?;
- let (signer, _) = extract_signer_and_apk_sections(apk)?;
+ let (signer, _) = extract_signer_and_apk_sections(apk, current_sdk)?;
Ok(signer.public_key.public_key_to_der()?.into_boxed_slice())
}
pub(crate) fn extract_signer_and_apk_sections<R: Read + Seek>(
apk: R,
+ current_sdk: u32,
) -> Result<(Signer, ApkSections<R>)> {
let mut sections = ApkSections::new(apk)?;
let mut block = sections.find_signature(APK_SIGNATURE_SCHEME_V3_BLOCK_ID).context(
"Fallback to v2 when v3 block not found is not yet implemented.", // b/197052981
)?;
- let mut supported = block
- .read::<Signers>()?
- .into_inner()
- .into_iter()
- .filter(|s| s.sdk_range().contains(&SDK_INT))
- .collect::<Vec<_>>();
+ let signers = block.read::<Signers>()?.into_inner();
+ let mut supported =
+ signers.into_iter().filter(|s| s.sdk_range().contains(¤t_sdk)).collect::<Vec<_>>();
ensure!(
supported.len() == 1,
"APK Signature Scheme V3 only supports one signer: {} signers found.",