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Pierre-Clément Tosi4f4f5eb2022-12-08 14:31:42 +00001// Copyright 2022, The Android Open Source Project
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15//! Support for DICE derivation and BCC generation.
16
Jiyong Parkb87f3302023-03-21 10:03:11 +090017use crate::cstr;
Pierre-Clément Tosibec84662023-01-04 14:25:33 +000018use crate::helpers::flushed_zeroize;
19use core::ffi::c_void;
Pierre-Clément Tosi4f4f5eb2022-12-08 14:31:42 +000020use core::ffi::CStr;
Alice Wang1f0add02023-01-23 16:22:53 +000021use core::mem::size_of;
Pierre-Clément Tosibec84662023-01-04 14:25:33 +000022use core::slice;
Pierre-Clément Tosif58f3a32023-02-02 16:24:23 +000023
Alice Wang843d8312023-02-15 09:47:06 +000024use diced_open_dice::{
25 bcc_format_config_descriptor, hash, Config, DiceMode, Hash, InputValues, HIDDEN_SIZE,
26};
Alice Wang1f0add02023-01-23 16:22:53 +000027use pvmfw_avb::{DebugLevel, Digest, VerifiedBootData};
28
Alice Wang31226132023-01-31 12:44:39 +000029fn to_dice_mode(debug_level: DebugLevel) -> DiceMode {
Alice Wang1f0add02023-01-23 16:22:53 +000030 match debug_level {
Alice Wang31226132023-01-31 12:44:39 +000031 DebugLevel::None => DiceMode::kDiceModeNormal,
32 DebugLevel::Full => DiceMode::kDiceModeDebug,
Alice Wang1f0add02023-01-23 16:22:53 +000033 }
34}
35
Alice Wang843d8312023-02-15 09:47:06 +000036fn to_dice_hash(verified_boot_data: &VerifiedBootData) -> diced_open_dice::Result<Hash> {
Alice Wang1f0add02023-01-23 16:22:53 +000037 let mut digests = [0u8; size_of::<Digest>() * 2];
38 digests[..size_of::<Digest>()].copy_from_slice(&verified_boot_data.kernel_digest);
39 if let Some(initrd_digest) = verified_boot_data.initrd_digest {
40 digests[size_of::<Digest>()..].copy_from_slice(&initrd_digest);
41 }
42 hash(&digests)
43}
Pierre-Clément Tosi4f4f5eb2022-12-08 14:31:42 +000044
Pierre-Clément Tosif58f3a32023-02-02 16:24:23 +000045pub struct PartialInputs {
Pierre-Clément Tosi1cc5eb72023-02-02 11:09:18 +000046 pub code_hash: Hash,
47 pub auth_hash: Hash,
48 pub mode: DiceMode,
Pierre-Clément Tosif58f3a32023-02-02 16:24:23 +000049}
Pierre-Clément Tosi4f4f5eb2022-12-08 14:31:42 +000050
Pierre-Clément Tosif58f3a32023-02-02 16:24:23 +000051impl PartialInputs {
Alice Wang843d8312023-02-15 09:47:06 +000052 pub fn new(data: &VerifiedBootData) -> diced_open_dice::Result<Self> {
Pierre-Clément Tosif58f3a32023-02-02 16:24:23 +000053 let code_hash = to_dice_hash(data)?;
54 let auth_hash = hash(data.public_key)?;
55 let mode = to_dice_mode(data.debug_level);
Pierre-Clément Tosi4f4f5eb2022-12-08 14:31:42 +000056
Pierre-Clément Tosif58f3a32023-02-02 16:24:23 +000057 Ok(Self { code_hash, auth_hash, mode })
58 }
59
Alice Wang843d8312023-02-15 09:47:06 +000060 pub fn into_input_values(
61 self,
62 salt: &[u8; HIDDEN_SIZE],
Alan Stokes4db76eb2023-04-26 14:28:15 +010063 config_descriptor_buffer: &mut [u8],
Alice Wang843d8312023-02-15 09:47:06 +000064 ) -> diced_open_dice::Result<InputValues> {
Pierre-Clément Tosif58f3a32023-02-02 16:24:23 +000065 let config_descriptor_size = bcc_format_config_descriptor(
Jiyong Parkb87f3302023-03-21 10:03:11 +090066 Some(cstr!("vm_entry")),
Pierre-Clément Tosif58f3a32023-02-02 16:24:23 +000067 None, // component_version
68 false, // resettable
Alan Stokes4db76eb2023-04-26 14:28:15 +010069 config_descriptor_buffer,
Pierre-Clément Tosif58f3a32023-02-02 16:24:23 +000070 )?;
71 let config = &config_descriptor_buffer[..config_descriptor_size];
72
73 Ok(InputValues::new(
74 self.code_hash,
75 Config::Descriptor(config),
76 self.auth_hash,
77 self.mode,
78 *salt,
79 ))
80 }
Pierre-Clément Tosi4f4f5eb2022-12-08 14:31:42 +000081}
Pierre-Clément Tosibec84662023-01-04 14:25:33 +000082
83/// Flushes data caches over the provided address range.
84///
85/// # Safety
86///
87/// The provided address and size must be to a valid address range (typically on the stack, .bss,
88/// .data, or provided BCC).
89#[no_mangle]
90unsafe extern "C" fn DiceClearMemory(_ctx: *mut c_void, size: usize, addr: *mut c_void) {
91 // SAFETY - We must trust that the slice will be valid arrays/variables on the C code stack.
92 let region = unsafe { slice::from_raw_parts_mut(addr as *mut u8, size) };
93 flushed_zeroize(region)
94}