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keys, disc, io: bus-encryption gates, halt-aware key paths, writeback error latching

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Read-time key fetches are validated and source, halt and drive faults
surface. Every BDMV/STREAM file is bus-decrypted per the BEE flag and
unit copy-permission bits; a missing or unparseable cert fails safe.
Extract treats a drive Stop as a halt, not a hole. io latches writeback
errors, fixes the read eviction window and never waits on writeback
during seeks.
This commit is contained in:
Matthew Jackson
2026-09-26 19:53:08 -07:00
parent aa85906a87
commit 4c5098ce75
36 changed files with 4975 additions and 892 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/aacs/content.rs
+9 -48
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@@ -251,12 +251,9 @@ pub fn encrypt_unit(unit: &mut [u8], unit_key: &[u8; 16]) -> bool {
/// Remove bus encryption from an aligned unit (AACS 2.0 / UHD).
/// Bus encryption uses read_data_key, decrypting bytes 16..2048 of each 2048-byte sector.
///
/// Widened from `pub(crate)` to `pub` (behavior unchanged) so an out-of-tree
/// diagnostic tool can invert AACS 2.0 bus encryption on sampled units after an
/// OEM host-cert AKE yields the Read Data Key — the same de-bus step the rip
/// path applies internally.
pub fn decrypt_bus(unit: &mut [u8], read_data_key: &[u8; 16]) {
/// Test-only unit-granular form; production de-busses via [`decrypt_bus_in_content`].
#[cfg(test)]
pub(crate) fn decrypt_bus(unit: &mut [u8], read_data_key: &[u8; 16]) {
// Expand the key schedule ONCE for the whole unit: `read_data_key` is
// loop-invariant, but per-sector `aes_cbc_decrypt` rebuilt it 3x per unit
// (~29M redundant expansions over a 90GB read) on the decrypt hot path.
@@ -273,49 +270,13 @@ pub fn decrypt_bus(unit: &mut [u8], read_data_key: &[u8; 16]) {
}
}
/// Remove bus encryption across a sector-aligned `buf`, gated to the disc's
/// encrypted-content ranges. `base_lba` is the LBA of `buf`'s first 2048-byte
/// sector (sector `i` = `base_lba + i`). A sector is de-bussed only when `ranges`
/// is `None` (content-only caller) or its LBA falls inside a sorted
/// `(start_lba, sector_count)` range — a clear UDF/nav sector outside content is
/// left untouched (de-bussing it would corrupt plaintext). Key schedule expanded
/// once. Single de-bus entry point (see the `sector::bus_removal` module doc).
pub(crate) fn decrypt_bus_in_content(
buf: &mut [u8],
read_data_key: &[u8; 16],
base_lba: u32,
ranges: Option<&[(u32, u32)]>,
) {
debug_assert!(
ranges.is_none_or(|rs| rs.windows(2).all(|w| w[0].0 <= w[1].0)),
"content ranges must be sorted ascending by start LBA for the binary search"
);
let in_content = |lba: u32| -> bool {
match ranges {
None => true,
// `rs` is sorted ascending by start and non-overlapping (merged
// extents), so binary-search the last range with start <= lba and
// test containment — O(log n) per sector, not O(ranges).
Some(rs) => {
let i = rs.partition_point(|&(start, _)| start <= lba);
i > 0 && {
let (start, cnt) = rs[i - 1];
(lba as u64) < start as u64 + cnt as u64
}
}
}
};
/// Remove bus encryption from every whole 2048-byte sector of `buf` (bytes
/// 16..2048 of each; the first 16 are plaintext on the wire). For content-only
/// callers; whole-disc readers gate through `sector::bus_removal::BusMap`.
pub(crate) fn decrypt_bus_sectors(buf: &mut [u8], read_data_key: &[u8; 16]) {
let cipher = crate::aacs::crypto::new_cipher_for(read_data_key);
for (i, sector) in buf.chunks_mut(SECTOR_BYTES).enumerate() {
if sector.len() < SECTOR_BYTES {
break; // trailing partial sector (never on a whole-sector read)
}
let lba = base_lba.saturating_add(i as u32);
if !in_content(lba) {
continue;
}
// First 16 bytes of each sector are plaintext on the wire.
crate::aacs::crypto::cbc_decrypt_blocks(&cipher, &mut sector[16..SECTOR_BYTES]);
for sector in buf.as_chunks_mut::<SECTOR_BYTES>().0 {
crate::aacs::crypto::cbc_decrypt_blocks(&cipher, &mut sector[16..]);
}
}