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Split bootloader implementation into multiple files

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Rasmus Melchior Jacobsen 2023-03-31 08:05:37 +02:00
parent 5955d81374
commit 373760a56b
5 changed files with 1194 additions and 1171 deletions
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526
embassy-boot/boot/src/boot_loader.rs Normal file
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use embedded_storage::nor_flash::{ErrorType, NorFlash, NorFlashError, NorFlashErrorKind, ReadNorFlash};
use crate::{Partition, State, BOOT_MAGIC, SWAP_MAGIC};
/// Errors returned by bootloader
#[derive(PartialEq, Eq, Debug)]
pub enum BootError {
/// Error from flash.
Flash(NorFlashErrorKind),
/// Invalid bootloader magic
BadMagic,
}
#[cfg(feature = "defmt")]
impl defmt::Format for BootError {
fn format(&self, fmt: defmt::Formatter) {
match self {
BootError::Flash(_) => defmt::write!(fmt, "BootError::Flash(_)"),
BootError::BadMagic => defmt::write!(fmt, "BootError::BadMagic"),
}
}
}
impl<E> From<E> for BootError
where
E: NorFlashError,
{
fn from(error: E) -> Self {
BootError::Flash(error.kind())
}
}
/// Extension of the embedded-storage flash type information with block size and erase value.
pub trait Flash: NorFlash + ReadNorFlash {
/// The block size that should be used when writing to flash. For most builtin flashes, this is the same as the erase
/// size of the flash, but for external QSPI flash modules, this can be lower.
const BLOCK_SIZE: usize;
/// The erase value of the flash. Typically the default of 0xFF is used, but some flashes use a different value.
const ERASE_VALUE: u8 = 0xFF;
}
/// Trait defining the flash handles used for active and DFU partition
pub trait FlashConfig {
/// Flash type used for the state partition.
type STATE: Flash;
/// Flash type used for the active partition.
type ACTIVE: Flash;
/// Flash type used for the dfu partition.
type DFU: Flash;
/// Return flash instance used to write/read to/from active partition.
fn active(&mut self) -> &mut Self::ACTIVE;
/// Return flash instance used to write/read to/from dfu partition.
fn dfu(&mut self) -> &mut Self::DFU;
/// Return flash instance used to write/read to/from bootloader state.
fn state(&mut self) -> &mut Self::STATE;
}
/// BootLoader works with any flash implementing embedded_storage and can also work with
/// different page sizes and flash write sizes.
pub struct BootLoader {
// Page with current state of bootloader. The state partition has the following format:
// | Range | Description |
// | 0 - WRITE_SIZE | Magic indicating bootloader state. BOOT_MAGIC means boot, SWAP_MAGIC means swap. |
// | WRITE_SIZE - N | Progress index used while swapping or reverting |
state: Partition,
// Location of the partition which will be booted from
active: Partition,
// Location of the partition which will be swapped in when requested
dfu: Partition,
}
impl BootLoader {
/// Create a new instance of a bootloader with the given partitions.
///
/// - All partitions must be aligned with the PAGE_SIZE const generic parameter.
/// - The dfu partition must be at least PAGE_SIZE bigger than the active partition.
pub fn new(active: Partition, dfu: Partition, state: Partition) -> Self {
Self { active, dfu, state }
}
/// Return the boot address for the active partition.
pub fn boot_address(&self) -> usize {
self.active.from
}
/// Perform necessary boot preparations like swapping images.
///
/// The DFU partition is assumed to be 1 page bigger than the active partition for the swap
/// algorithm to work correctly.
///
/// SWAPPING
///
/// Assume a flash size of 3 pages for the active partition, and 4 pages for the DFU partition.
/// The swap index contains the copy progress, as to allow continuation of the copy process on
/// power failure. The index counter is represented within 1 or more pages (depending on total
/// flash size), where a page X is considered swapped if index at location (X + WRITE_SIZE)
/// contains a zero value. This ensures that index updates can be performed atomically and
/// avoid a situation where the wrong index value is set (page write size is "atomic").
///
/// +-----------+------------+--------+--------+--------+--------+
/// | Partition | Swap Index | Page 0 | Page 1 | Page 3 | Page 4 |
/// +-----------+------------+--------+--------+--------+--------+
/// | Active | 0 | 1 | 2 | 3 | - |
/// | DFU | 0 | 3 | 2 | 1 | X |
/// +-----------+------------+--------+--------+--------+--------+
///
/// The algorithm starts by copying 'backwards', and after the first step, the layout is
/// as follows:
///
/// +-----------+------------+--------+--------+--------+--------+
/// | Partition | Swap Index | Page 0 | Page 1 | Page 3 | Page 4 |
/// +-----------+------------+--------+--------+--------+--------+
/// | Active | 1 | 1 | 2 | 1 | - |
/// | DFU | 1 | 3 | 2 | 1 | 3 |
/// +-----------+------------+--------+--------+--------+--------+
///
/// The next iteration performs the same steps
///
/// +-----------+------------+--------+--------+--------+--------+
/// | Partition | Swap Index | Page 0 | Page 1 | Page 3 | Page 4 |
/// +-----------+------------+--------+--------+--------+--------+
/// | Active | 2 | 1 | 2 | 1 | - |
/// | DFU | 2 | 3 | 2 | 2 | 3 |
/// +-----------+------------+--------+--------+--------+--------+
///
/// And again until we're done
///
/// +-----------+------------+--------+--------+--------+--------+
/// | Partition | Swap Index | Page 0 | Page 1 | Page 3 | Page 4 |
/// +-----------+------------+--------+--------+--------+--------+
/// | Active | 3 | 3 | 2 | 1 | - |
/// | DFU | 3 | 3 | 1 | 2 | 3 |
/// +-----------+------------+--------+--------+--------+--------+
///
/// REVERTING
///
/// The reverting algorithm uses the swap index to discover that images were swapped, but that
/// the application failed to mark the boot successful. In this case, the revert algorithm will
/// run.
///
/// The revert index is located separately from the swap index, to ensure that revert can continue
/// on power failure.
///
/// The revert algorithm works forwards, by starting copying into the 'unused' DFU page at the start.
///
/// +-----------+--------------+--------+--------+--------+--------+
/// | Partition | Revert Index | Page 0 | Page 1 | Page 3 | Page 4 |
//*/
/// +-----------+--------------+--------+--------+--------+--------+
/// | Active | 3 | 1 | 2 | 1 | - |
/// | DFU | 3 | 3 | 1 | 2 | 3 |
/// +-----------+--------------+--------+--------+--------+--------+
///
///
/// +-----------+--------------+--------+--------+--------+--------+
/// | Partition | Revert Index | Page 0 | Page 1 | Page 3 | Page 4 |
/// +-----------+--------------+--------+--------+--------+--------+
/// | Active | 3 | 1 | 2 | 1 | - |
/// | DFU | 3 | 3 | 2 | 2 | 3 |
/// +-----------+--------------+--------+--------+--------+--------+
///
/// +-----------+--------------+--------+--------+--------+--------+
/// | Partition | Revert Index | Page 0 | Page 1 | Page 3 | Page 4 |
/// +-----------+--------------+--------+--------+--------+--------+
/// | Active | 3 | 1 | 2 | 3 | - |
/// | DFU | 3 | 3 | 2 | 1 | 3 |
/// +-----------+--------------+--------+--------+--------+--------+
///
pub fn prepare_boot<P: FlashConfig>(
&mut self,
p: &mut P,
magic: &mut [u8],
page: &mut [u8],
) -> Result<State, BootError> {
// Ensure we have enough progress pages to store copy progress
assert_partitions(self.active, self.dfu, self.state, page.len(), P::STATE::WRITE_SIZE);
assert_eq!(magic.len(), P::STATE::WRITE_SIZE);
// Copy contents from partition N to active
let state = self.read_state(p, magic)?;
if state == State::Swap {
//
// Check if we already swapped. If we're in the swap state, this means we should revert
// since the app has failed to mark boot as successful
//
if !self.is_swapped(p, magic, page)? {
trace!("Swapping");
self.swap(p, magic, page)?;
trace!("Swapping done");
} else {
trace!("Reverting");
self.revert(p, magic, page)?;
// Overwrite magic and reset progress
let fstate = p.state();
magic.fill(!P::STATE::ERASE_VALUE);
fstate.write(self.state.from as u32, magic)?;
fstate.erase(self.state.from as u32, self.state.to as u32)?;
magic.fill(BOOT_MAGIC);
fstate.write(self.state.from as u32, magic)?;
}
}
Ok(state)
}
fn is_swapped<P: FlashConfig>(&mut self, p: &mut P, magic: &mut [u8], page: &mut [u8]) -> Result<bool, BootError> {
let page_size = page.len();
let page_count = self.active.len() / page_size;
let progress = self.current_progress(p, magic)?;
Ok(progress >= page_count * 2)
}
fn current_progress<P: FlashConfig>(&mut self, config: &mut P, aligned: &mut [u8]) -> Result<usize, BootError> {
let write_size = aligned.len();
let max_index = ((self.state.len() - write_size) / write_size) - 1;
aligned.fill(!P::STATE::ERASE_VALUE);
let flash = config.state();
for i in 0..max_index {
flash.read((self.state.from + write_size + i * write_size) as u32, aligned)?;
if aligned.iter().any(|&b| b == P::STATE::ERASE_VALUE) {
return Ok(i);
}
}
Ok(max_index)
}
fn update_progress<P: FlashConfig>(&mut self, idx: usize, p: &mut P, magic: &mut [u8]) -> Result<(), BootError> {
let flash = p.state();
let write_size = magic.len();
let w = self.state.from + write_size + idx * write_size;
let aligned = magic;
aligned.fill(!P::STATE::ERASE_VALUE);
flash.write(w as u32, aligned)?;
Ok(())
}
fn active_addr(&self, n: usize, page_size: usize) -> usize {
self.active.from + n * page_size
}
fn dfu_addr(&self, n: usize, page_size: usize) -> usize {
self.dfu.from + n * page_size
}
fn copy_page_once_to_active<P: FlashConfig>(
&mut self,
idx: usize,
from_page: usize,
to_page: usize,
p: &mut P,
magic: &mut [u8],
page: &mut [u8],
) -> Result<(), BootError> {
let buf = page;
if self.current_progress(p, magic)? <= idx {
let mut offset = from_page;
for chunk in buf.chunks_mut(P::DFU::BLOCK_SIZE) {
p.dfu().read(offset as u32, chunk)?;
offset += chunk.len();
}
p.active().erase(to_page as u32, (to_page + buf.len()) as u32)?;
let mut offset = to_page;
for chunk in buf.chunks(P::ACTIVE::BLOCK_SIZE) {
p.active().write(offset as u32, chunk)?;
offset += chunk.len();
}
self.update_progress(idx, p, magic)?;
}
Ok(())
}
fn copy_page_once_to_dfu<P: FlashConfig>(
&mut self,
idx: usize,
from_page: usize,
to_page: usize,
p: &mut P,
magic: &mut [u8],
page: &mut [u8],
) -> Result<(), BootError> {
let buf = page;
if self.current_progress(p, magic)? <= idx {
let mut offset = from_page;
for chunk in buf.chunks_mut(P::ACTIVE::BLOCK_SIZE) {
p.active().read(offset as u32, chunk)?;
offset += chunk.len();
}
p.dfu().erase(to_page as u32, (to_page + buf.len()) as u32)?;
let mut offset = to_page;
for chunk in buf.chunks(P::DFU::BLOCK_SIZE) {
p.dfu().write(offset as u32, chunk)?;
offset += chunk.len();
}
self.update_progress(idx, p, magic)?;
}
Ok(())
}
fn swap<P: FlashConfig>(&mut self, p: &mut P, magic: &mut [u8], page: &mut [u8]) -> Result<(), BootError> {
let page_size = page.len();
let page_count = self.active.len() / page_size;
trace!("Page count: {}", page_count);
for page_num in 0..page_count {
trace!("COPY PAGE {}", page_num);
// Copy active page to the 'next' DFU page.
let active_page = self.active_addr(page_count - 1 - page_num, page_size);
let dfu_page = self.dfu_addr(page_count - page_num, page_size);
//trace!("Copy active {} to dfu {}", active_page, dfu_page);
self.copy_page_once_to_dfu(page_num * 2, active_page, dfu_page, p, magic, page)?;
// Copy DFU page to the active page
let active_page = self.active_addr(page_count - 1 - page_num, page_size);
let dfu_page = self.dfu_addr(page_count - 1 - page_num, page_size);
//trace!("Copy dfy {} to active {}", dfu_page, active_page);
self.copy_page_once_to_active(page_num * 2 + 1, dfu_page, active_page, p, magic, page)?;
}
Ok(())
}
fn revert<P: FlashConfig>(&mut self, p: &mut P, magic: &mut [u8], page: &mut [u8]) -> Result<(), BootError> {
let page_size = page.len();
let page_count = self.active.len() / page_size;
for page_num in 0..page_count {
// Copy the bad active page to the DFU page
let active_page = self.active_addr(page_num, page_size);
let dfu_page = self.dfu_addr(page_num, page_size);
self.copy_page_once_to_dfu(page_count * 2 + page_num * 2, active_page, dfu_page, p, magic, page)?;
// Copy the DFU page back to the active page
let active_page = self.active_addr(page_num, page_size);
let dfu_page = self.dfu_addr(page_num + 1, page_size);
self.copy_page_once_to_active(page_count * 2 + page_num * 2 + 1, dfu_page, active_page, p, magic, page)?;
}
Ok(())
}
fn read_state<P: FlashConfig>(&mut self, config: &mut P, magic: &mut [u8]) -> Result<State, BootError> {
let flash = config.state();
flash.read(self.state.from as u32, magic)?;
if !magic.iter().any(|&b| b != SWAP_MAGIC) {
Ok(State::Swap)
} else {
Ok(State::Boot)
}
}
}
fn assert_partitions(active: Partition, dfu: Partition, state: Partition, page_size: usize, write_size: usize) {
assert_eq!(active.len() % page_size, 0);
assert_eq!(dfu.len() % page_size, 0);
assert!(dfu.len() - active.len() >= page_size);
assert!(2 * (active.len() / page_size) <= (state.len() - write_size) / write_size);
}
/// A flash wrapper implementing the Flash and embedded_storage traits.
pub struct BootFlash<F, const BLOCK_SIZE: usize, const ERASE_VALUE: u8 = 0xFF>
where
F: NorFlash + ReadNorFlash,
{
flash: F,
}
impl<F, const BLOCK_SIZE: usize, const ERASE_VALUE: u8> BootFlash<F, BLOCK_SIZE, ERASE_VALUE>
where
F: NorFlash + ReadNorFlash,
{
/// Create a new instance of a bootable flash
pub fn new(flash: F) -> Self {
Self { flash }
}
}
impl<F, const BLOCK_SIZE: usize, const ERASE_VALUE: u8> Flash for BootFlash<F, BLOCK_SIZE, ERASE_VALUE>
where
F: NorFlash + ReadNorFlash,
{
const BLOCK_SIZE: usize = BLOCK_SIZE;
const ERASE_VALUE: u8 = ERASE_VALUE;
}
impl<F, const BLOCK_SIZE: usize, const ERASE_VALUE: u8> ErrorType for BootFlash<F, BLOCK_SIZE, ERASE_VALUE>
where
F: ReadNorFlash + NorFlash,
{
type Error = F::Error;
}
impl<F, const BLOCK_SIZE: usize, const ERASE_VALUE: u8> NorFlash for BootFlash<F, BLOCK_SIZE, ERASE_VALUE>
where
F: ReadNorFlash + NorFlash,
{
const WRITE_SIZE: usize = F::WRITE_SIZE;
const ERASE_SIZE: usize = F::ERASE_SIZE;
fn erase(&mut self, from: u32, to: u32) -> Result<(), Self::Error> {
F::erase(&mut self.flash, from, to)
}
fn write(&mut self, offset: u32, bytes: &[u8]) -> Result<(), Self::Error> {
F::write(&mut self.flash, offset, bytes)
}
}
impl<F, const BLOCK_SIZE: usize, const ERASE_VALUE: u8> ReadNorFlash for BootFlash<F, BLOCK_SIZE, ERASE_VALUE>
where
F: ReadNorFlash + NorFlash,
{
const READ_SIZE: usize = F::READ_SIZE;
fn read(&mut self, offset: u32, bytes: &mut [u8]) -> Result<(), Self::Error> {
F::read(&mut self.flash, offset, bytes)
}
fn capacity(&self) -> usize {
F::capacity(&self.flash)
}
}
/// Convenience provider that uses a single flash for all partitions.
pub struct SingleFlashConfig<'a, F>
where
F: Flash,
{
flash: &'a mut F,
}
impl<'a, F> SingleFlashConfig<'a, F>
where
F: Flash,
{
/// Create a provider for a single flash.
pub fn new(flash: &'a mut F) -> Self {
Self { flash }
}
}
impl<'a, F> FlashConfig for SingleFlashConfig<'a, F>
where
F: Flash,
{
type STATE = F;
type ACTIVE = F;
type DFU = F;
fn active(&mut self) -> &mut Self::STATE {
self.flash
}
fn dfu(&mut self) -> &mut Self::ACTIVE {
self.flash
}
fn state(&mut self) -> &mut Self::DFU {
self.flash
}
}
/// Convenience flash provider that uses separate flash instances for each partition.
pub struct MultiFlashConfig<'a, ACTIVE, STATE, DFU>
where
ACTIVE: Flash,
STATE: Flash,
DFU: Flash,
{
active: &'a mut ACTIVE,
state: &'a mut STATE,
dfu: &'a mut DFU,
}
impl<'a, ACTIVE, STATE, DFU> MultiFlashConfig<'a, ACTIVE, STATE, DFU>
where
ACTIVE: Flash,
STATE: Flash,
DFU: Flash,
{
/// Create a new flash provider with separate configuration for all three partitions.
pub fn new(active: &'a mut ACTIVE, state: &'a mut STATE, dfu: &'a mut DFU) -> Self {
Self { active, state, dfu }
}
}
impl<'a, ACTIVE, STATE, DFU> FlashConfig for MultiFlashConfig<'a, ACTIVE, STATE, DFU>
where
ACTIVE: Flash,
STATE: Flash,
DFU: Flash,
{
type STATE = STATE;
type ACTIVE = ACTIVE;
type DFU = DFU;
fn active(&mut self) -> &mut Self::ACTIVE {
self.active
}
fn dfu(&mut self) -> &mut Self::DFU {
self.dfu
}
fn state(&mut self) -> &mut Self::STATE {
self.state
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
#[should_panic]
fn test_range_asserts() {
const ACTIVE: Partition = Partition::new(4096, 4194304);
const DFU: Partition = Partition::new(4194304, 2 * 4194304);
const STATE: Partition = Partition::new(0, 4096);
assert_partitions(ACTIVE, DFU, STATE, 4096, 4);
}
}

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embassy-boot/boot/src/firmware_updater.rs Normal file
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use embedded_storage::nor_flash::{NorFlash, NorFlashError, NorFlashErrorKind};
use embedded_storage_async::nor_flash::NorFlash as AsyncNorFlash;
use crate::{FirmwareWriter, Partition, State, BOOT_MAGIC, SWAP_MAGIC};
/// Errors returned by FirmwareUpdater
#[derive(Debug)]
pub enum FirmwareUpdaterError {
/// Error from flash.
Flash(NorFlashErrorKind),
/// Signature errors.
Signature(signature::Error),
}
#[cfg(feature = "defmt")]
impl defmt::Format for FirmwareUpdaterError {
fn format(&self, fmt: defmt::Formatter) {
match self {
FirmwareUpdaterError::Flash(_) => defmt::write!(fmt, "FirmwareUpdaterError::Flash(_)"),
FirmwareUpdaterError::Signature(_) => defmt::write!(fmt, "FirmwareUpdaterError::Signature(_)"),
}
}
}
impl<E> From<E> for FirmwareUpdaterError
where
E: NorFlashError,
{
fn from(error: E) -> Self {
FirmwareUpdaterError::Flash(error.kind())
}
}
/// FirmwareUpdater is an application API for interacting with the BootLoader without the ability to
/// 'mess up' the internal bootloader state
pub struct FirmwareUpdater {
state: Partition,
dfu: Partition,
}
impl Default for FirmwareUpdater {
fn default() -> Self {
extern "C" {
static __bootloader_state_start: u32;
static __bootloader_state_end: u32;
static __bootloader_dfu_start: u32;
static __bootloader_dfu_end: u32;
}
let dfu = unsafe {
Partition::new(
&__bootloader_dfu_start as *const u32 as usize,
&__bootloader_dfu_end as *const u32 as usize,
)
};
let state = unsafe {
Partition::new(
&__bootloader_state_start as *const u32 as usize,
&__bootloader_state_end as *const u32 as usize,
)
};
trace!("DFU: 0x{:x} - 0x{:x}", dfu.from, dfu.to);
trace!("STATE: 0x{:x} - 0x{:x}", state.from, state.to);
FirmwareUpdater::new(dfu, state)
}
}
impl FirmwareUpdater {
/// Create a firmware updater instance with partition ranges for the update and state partitions.
pub const fn new(dfu: Partition, state: Partition) -> Self {
Self { dfu, state }
}
/// Return the length of the DFU area
pub fn firmware_len(&self) -> usize {
self.dfu.len()
}
/// Obtain the current state.
///
/// This is useful to check if the bootloader has just done a swap, in order
/// to do verifications and self-tests of the new image before calling
/// `mark_booted`.
pub async fn get_state<F: AsyncNorFlash>(
&mut self,
flash: &mut F,
aligned: &mut [u8],
) -> Result<State, FirmwareUpdaterError> {
flash.read(self.state.from as u32, aligned).await?;
if !aligned.iter().any(|&b| b != SWAP_MAGIC) {
Ok(State::Swap)
} else {
Ok(State::Boot)
}
}
/// Verify the DFU given a public key. If there is an error then DO NOT
/// proceed with updating the firmware as it must be signed with a
/// corresponding private key (otherwise it could be malicious firmware).
///
/// Mark to trigger firmware swap on next boot if verify suceeds.
///
/// If the "ed25519-salty" feature is set (or another similar feature) then the signature is expected to have
/// been generated from a SHA-512 digest of the firmware bytes.
///
/// If no signature feature is set then this method will always return a
/// signature error.
///
/// # Safety
///
/// The `_aligned` buffer must have a size of F::WRITE_SIZE, and follow the alignment rules for the flash being read from
/// and written to.
#[cfg(feature = "_verify")]
pub async fn verify_and_mark_updated<F: AsyncNorFlash>(
&mut self,
_flash: &mut F,
_public_key: &[u8],
_signature: &[u8],
_update_len: usize,
_aligned: &mut [u8],
) -> Result<(), FirmwareUpdaterError> {
let _end = self.dfu.from + _update_len;
let _read_size = _aligned.len();
assert_eq!(_aligned.len(), F::WRITE_SIZE);
assert!(_end <= self.dfu.to);
#[cfg(feature = "ed25519-dalek")]
{
use ed25519_dalek::{Digest, PublicKey, Sha512, Signature, SignatureError, Verifier};
let into_signature_error = |e: SignatureError| FirmwareUpdaterError::Signature(e.into());
let public_key = PublicKey::from_bytes(_public_key).map_err(into_signature_error)?;
let signature = Signature::from_bytes(_signature).map_err(into_signature_error)?;
let mut digest = Sha512::new();
let mut offset = self.dfu.from;
let last_offset = _end / _read_size * _read_size;
while offset < last_offset {
_flash.read(offset as u32, _aligned).await?;
digest.update(&_aligned);
offset += _read_size;
}
let remaining = _end % _read_size;
if remaining > 0 {
_flash.read(last_offset as u32, _aligned).await?;
digest.update(&_aligned[0..remaining]);
}
public_key
.verify(&digest.finalize(), &signature)
.map_err(into_signature_error)?
}
#[cfg(feature = "ed25519-salty")]
{
use salty::constants::{PUBLICKEY_SERIALIZED_LENGTH, SIGNATURE_SERIALIZED_LENGTH};
use salty::{PublicKey, Sha512, Signature};
fn into_signature_error<E>(_: E) -> FirmwareUpdaterError {
FirmwareUpdaterError::Signature(signature::Error::default())
}
let public_key: [u8; PUBLICKEY_SERIALIZED_LENGTH] = _public_key.try_into().map_err(into_signature_error)?;
let public_key = PublicKey::try_from(&public_key).map_err(into_signature_error)?;
let signature: [u8; SIGNATURE_SERIALIZED_LENGTH] = _signature.try_into().map_err(into_signature_error)?;
let signature = Signature::try_from(&signature).map_err(into_signature_error)?;
let mut digest = Sha512::new();
let mut offset = self.dfu.from;
let last_offset = _end / _read_size * _read_size;
while offset < last_offset {
_flash.read(offset as u32, _aligned).await?;
digest.update(&_aligned);
offset += _read_size;
}
let remaining = _end % _read_size;
if remaining > 0 {
_flash.read(last_offset as u32, _aligned).await?;
digest.update(&_aligned[0..remaining]);
}
let message = digest.finalize();
let r = public_key.verify(&message, &signature);
trace!(
"Verifying with public key {}, signature {} and message {} yields ok: {}",
public_key.to_bytes(),
signature.to_bytes(),
message,
r.is_ok()
);
r.map_err(into_signature_error)?
}
self.set_magic(_aligned, SWAP_MAGIC, _flash).await
}
/// Mark to trigger firmware swap on next boot.
///
/// # Safety
///
/// The `aligned` buffer must have a size of F::WRITE_SIZE, and follow the alignment rules for the flash being written to.
#[cfg(not(feature = "_verify"))]
pub async fn mark_updated<F: AsyncNorFlash>(
&mut self,
flash: &mut F,
aligned: &mut [u8],
) -> Result<(), FirmwareUpdaterError> {
assert_eq!(aligned.len(), F::WRITE_SIZE);
self.set_magic(aligned, SWAP_MAGIC, flash).await
}
/// Mark firmware boot successful and stop rollback on reset.
///
/// # Safety
///
/// The `aligned` buffer must have a size of F::WRITE_SIZE, and follow the alignment rules for the flash being written to.
pub async fn mark_booted<F: AsyncNorFlash>(
&mut self,
flash: &mut F,
aligned: &mut [u8],
) -> Result<(), FirmwareUpdaterError> {
assert_eq!(aligned.len(), F::WRITE_SIZE);
self.set_magic(aligned, BOOT_MAGIC, flash).await
}
async fn set_magic<F: AsyncNorFlash>(
&mut self,
aligned: &mut [u8],
magic: u8,
flash: &mut F,
) -> Result<(), FirmwareUpdaterError> {
flash.read(self.state.from as u32, aligned).await?;
if aligned.iter().any(|&b| b != magic) {
aligned.fill(0);
flash.write(self.state.from as u32, aligned).await?;
flash.erase(self.state.from as u32, self.state.to as u32).await?;
aligned.fill(magic);
flash.write(self.state.from as u32, aligned).await?;
}
Ok(())
}
/// Write data to a flash page.
///
/// The buffer must follow alignment requirements of the target flash and a multiple of page size big.
///
/// # Safety
///
/// Failing to meet alignment and size requirements may result in a panic.
pub async fn write_firmware<F: AsyncNorFlash>(
&mut self,
offset: usize,
data: &[u8],
flash: &mut F,
block_size: usize,
) -> Result<(), FirmwareUpdaterError> {
assert!(data.len() >= F::ERASE_SIZE);
flash
.erase(
(self.dfu.from + offset) as u32,
(self.dfu.from + offset + data.len()) as u32,
)
.await?;
trace!(
"Erased from {} to {}",
self.dfu.from + offset,
self.dfu.from + offset + data.len()
);
FirmwareWriter(self.dfu)
.write_block(offset, data, flash, block_size)
.await?;
Ok(())
}
/// Prepare for an incoming DFU update by erasing the entire DFU area and
/// returning a `FirmwareWriter`.
///
/// Using this instead of `write_firmware` allows for an optimized API in
/// exchange for added complexity.
pub async fn prepare_update<F: AsyncNorFlash>(
&mut self,
flash: &mut F,
) -> Result<FirmwareWriter, FirmwareUpdaterError> {
flash.erase((self.dfu.from) as u32, (self.dfu.to) as u32).await?;
trace!("Erased from {} to {}", self.dfu.from, self.dfu.to);
Ok(FirmwareWriter(self.dfu))
}
//
// Blocking API
//
/// Obtain the current state.
///
/// This is useful to check if the bootloader has just done a swap, in order
/// to do verifications and self-tests of the new image before calling
/// `mark_booted`.
pub fn get_state_blocking<F: NorFlash>(
&mut self,
flash: &mut F,
aligned: &mut [u8],
) -> Result<State, FirmwareUpdaterError> {
flash.read(self.state.from as u32, aligned)?;
if !aligned.iter().any(|&b| b != SWAP_MAGIC) {
Ok(State::Swap)
} else {
Ok(State::Boot)
}
}
/// Verify the DFU given a public key. If there is an error then DO NOT
/// proceed with updating the firmware as it must be signed with a
/// corresponding private key (otherwise it could be malicious firmware).
///
/// Mark to trigger firmware swap on next boot if verify suceeds.
///
/// If the "ed25519-salty" feature is set (or another similar feature) then the signature is expected to have
/// been generated from a SHA-512 digest of the firmware bytes.
///
/// If no signature feature is set then this method will always return a
/// signature error.
///
/// # Safety
///
/// The `_aligned` buffer must have a size of F::WRITE_SIZE, and follow the alignment rules for the flash being read from
/// and written to.
#[cfg(feature = "_verify")]
pub fn verify_and_mark_updated_blocking<F: NorFlash>(
&mut self,
_flash: &mut F,
_public_key: &[u8],
_signature: &[u8],
_update_len: usize,
_aligned: &mut [u8],
) -> Result<(), FirmwareUpdaterError> {
let _end = self.dfu.from + _update_len;
let _read_size = _aligned.len();
assert_eq!(_aligned.len(), F::WRITE_SIZE);
assert!(_end <= self.dfu.to);
#[cfg(feature = "ed25519-dalek")]
{
use ed25519_dalek::{Digest, PublicKey, Sha512, Signature, SignatureError, Verifier};
let into_signature_error = |e: SignatureError| FirmwareUpdaterError::Signature(e.into());
let public_key = PublicKey::from_bytes(_public_key).map_err(into_signature_error)?;
let signature = Signature::from_bytes(_signature).map_err(into_signature_error)?;
let mut digest = Sha512::new();
let mut offset = self.dfu.from;
let last_offset = _end / _read_size * _read_size;
while offset < last_offset {
_flash.read(offset as u32, _aligned)?;
digest.update(&_aligned);
offset += _read_size;
}
let remaining = _end % _read_size;
if remaining > 0 {
_flash.read(last_offset as u32, _aligned)?;
digest.update(&_aligned[0..remaining]);
}
public_key
.verify(&digest.finalize(), &signature)
.map_err(into_signature_error)?
}
#[cfg(feature = "ed25519-salty")]
{
use salty::constants::{PUBLICKEY_SERIALIZED_LENGTH, SIGNATURE_SERIALIZED_LENGTH};
use salty::{PublicKey, Sha512, Signature};
fn into_signature_error<E>(_: E) -> FirmwareUpdaterError {
FirmwareUpdaterError::Signature(signature::Error::default())
}
let public_key: [u8; PUBLICKEY_SERIALIZED_LENGTH] = _public_key.try_into().map_err(into_signature_error)?;
let public_key = PublicKey::try_from(&public_key).map_err(into_signature_error)?;
let signature: [u8; SIGNATURE_SERIALIZED_LENGTH] = _signature.try_into().map_err(into_signature_error)?;
let signature = Signature::try_from(&signature).map_err(into_signature_error)?;
let mut digest = Sha512::new();
let mut offset = self.dfu.from;
let last_offset = _end / _read_size * _read_size;
while offset < last_offset {
_flash.read(offset as u32, _aligned)?;
digest.update(&_aligned);
offset += _read_size;
}
let remaining = _end % _read_size;
if remaining > 0 {
_flash.read(last_offset as u32, _aligned)?;
digest.update(&_aligned[0..remaining]);
}
let message = digest.finalize();
let r = public_key.verify(&message, &signature);
trace!(
"Verifying with public key {}, signature {} and message {} yields ok: {}",
public_key.to_bytes(),
signature.to_bytes(),
message,
r.is_ok()
);
r.map_err(into_signature_error)?
}
self.set_magic_blocking(_aligned, SWAP_MAGIC, _flash)
}
/// Mark to trigger firmware swap on next boot.
///
/// # Safety
///
/// The `aligned` buffer must have a size of F::WRITE_SIZE, and follow the alignment rules for the flash being written to.
#[cfg(not(feature = "_verify"))]
pub fn mark_updated_blocking<F: NorFlash>(
&mut self,
flash: &mut F,
aligned: &mut [u8],
) -> Result<(), FirmwareUpdaterError> {
assert_eq!(aligned.len(), F::WRITE_SIZE);
self.set_magic_blocking(aligned, SWAP_MAGIC, flash)
}
/// Mark firmware boot successful and stop rollback on reset.
///
/// # Safety
///
/// The `aligned` buffer must have a size of F::WRITE_SIZE, and follow the alignment rules for the flash being written to.
pub fn mark_booted_blocking<F: NorFlash>(
&mut self,
flash: &mut F,
aligned: &mut [u8],
) -> Result<(), FirmwareUpdaterError> {
assert_eq!(aligned.len(), F::WRITE_SIZE);
self.set_magic_blocking(aligned, BOOT_MAGIC, flash)
}
fn set_magic_blocking<F: NorFlash>(
&mut self,
aligned: &mut [u8],
magic: u8,
flash: &mut F,
) -> Result<(), FirmwareUpdaterError> {
flash.read(self.state.from as u32, aligned)?;
if aligned.iter().any(|&b| b != magic) {
aligned.fill(0);
flash.write(self.state.from as u32, aligned)?;
flash.erase(self.state.from as u32, self.state.to as u32)?;
aligned.fill(magic);
flash.write(self.state.from as u32, aligned)?;
}
Ok(())
}
/// Write data to a flash page.
///
/// The buffer must follow alignment requirements of the target flash and a multiple of page size big.
///
/// # Safety
///
/// Failing to meet alignment and size requirements may result in a panic.
pub fn write_firmware_blocking<F: NorFlash>(
&mut self,
offset: usize,
data: &[u8],
flash: &mut F,
block_size: usize,
) -> Result<(), FirmwareUpdaterError> {
assert!(data.len() >= F::ERASE_SIZE);
flash.erase(
(self.dfu.from + offset) as u32,
(self.dfu.from + offset + data.len()) as u32,
)?;
trace!(
"Erased from {} to {}",
self.dfu.from + offset,
self.dfu.from + offset + data.len()
);
FirmwareWriter(self.dfu).write_block_blocking(offset, data, flash, block_size)?;
Ok(())
}
/// Prepare for an incoming DFU update by erasing the entire DFU area and
/// returning a `FirmwareWriter`.
///
/// Using this instead of `write_firmware_blocking` allows for an optimized
/// API in exchange for added complexity.
pub fn prepare_update_blocking<F: NorFlash>(
&mut self,
flash: &mut F,
) -> Result<FirmwareWriter, FirmwareUpdaterError> {
flash.erase((self.dfu.from) as u32, (self.dfu.to) as u32)?;
trace!("Erased from {} to {}", self.dfu.from, self.dfu.to);
Ok(FirmwareWriter(self.dfu))
}
}

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embassy-boot/boot/src/firmware_writer.rs Normal file
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use embedded_storage::nor_flash::NorFlash;
use embedded_storage_async::nor_flash::NorFlash as AsyncNorFlash;
use crate::Partition;
/// FirmwareWriter allows writing blocks to an already erased flash.
pub struct FirmwareWriter(pub(crate) Partition);
impl FirmwareWriter {
/// Write data to a flash page.
///
/// The buffer must follow alignment requirements of the target flash and a multiple of page size big.
///
/// # Safety
///
/// Failing to meet alignment and size requirements may result in a panic.
pub async fn write_block<F: AsyncNorFlash>(
&mut self,
offset: usize,
data: &[u8],
flash: &mut F,
block_size: usize,
) -> Result<(), F::Error> {
trace!(
"Writing firmware at offset 0x{:x} len {}",
self.0.from + offset,
data.len()
);
let mut write_offset = self.0.from + offset;
for chunk in data.chunks(block_size) {
trace!("Wrote chunk at {}: {:?}", write_offset, chunk);
flash.write(write_offset as u32, chunk).await?;
write_offset += chunk.len();
}
/*
trace!("Wrote data, reading back for verification");
let mut buf: [u8; 4096] = [0; 4096];
let mut data_offset = 0;
let mut read_offset = self.dfu.from + offset;
for chunk in buf.chunks_mut(block_size) {
flash.read(read_offset as u32, chunk).await?;
trace!("Read chunk at {}: {:?}", read_offset, chunk);
assert_eq!(&data[data_offset..data_offset + block_size], chunk);
read_offset += chunk.len();
data_offset += chunk.len();
}
*/
Ok(())
}
/// Write data to a flash page.
///
/// The buffer must follow alignment requirements of the target flash and a multiple of page size big.
///
/// # Safety
///
/// Failing to meet alignment and size requirements may result in a panic.
pub fn write_block_blocking<F: NorFlash>(
&mut self,
offset: usize,
data: &[u8],
flash: &mut F,
block_size: usize,
) -> Result<(), F::Error> {
trace!(
"Writing firmware at offset 0x{:x} len {}",
self.0.from + offset,
data.len()
);
let mut write_offset = self.0.from + offset;
for chunk in data.chunks(block_size) {
trace!("Wrote chunk at {}: {:?}", write_offset, chunk);
flash.write(write_offset as u32, chunk)?;
write_offset += chunk.len();
}
/*
trace!("Wrote data, reading back for verification");
let mut buf: [u8; 4096] = [0; 4096];
let mut data_offset = 0;
let mut read_offset = self.dfu.from + offset;
for chunk in buf.chunks_mut(block_size) {
flash.read(read_offset as u32, chunk).await?;
trace!("Read chunk at {}: {:?}", read_offset, chunk);
assert_eq!(&data[data_offset..data_offset + block_size], chunk);
read_offset += chunk.len();
data_offset += chunk.len();
}
*/
Ok(())
}
}

1183
embassy-boot/boot/src/lib.rs
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22
embassy-boot/boot/src/partition.rs Normal file
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/// A region in flash used by the bootloader.
#[derive(Copy, Clone, Debug)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
pub struct Partition {
/// Start of the flash region.
pub from: usize,
/// End of the flash region.
pub to: usize,
}
impl Partition {
/// Create a new partition with the provided range
pub const fn new(from: usize, to: usize) -> Self {
Self { from, to }
}
/// Return the length of the partition
#[allow(clippy::len_without_is_empty)]
pub const fn len(&self) -> usize {
self.to - self.from
}
}