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Use new persistent store library (and delete old)

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This commit is contained in:
Julien Cretin
2020-11-11 12:55:37 +01:00
parent 8d33c7866d
commit 5673b9148f
12 changed files with 493 additions and 2937 deletions
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3
Cargo.toml
View File

@@ -15,6 +15,7 @@ libtock_drivers = { path = "third_party/libtock-drivers" }
lang_items = { path = "third_party/lang-items" }
cbor = { path = "libraries/cbor" }
crypto = { path = "libraries/crypto" }
persistent_store = { path = "libraries/persistent_store" }
byteorder = { version = "1", default-features = false }
arrayref = "0.3.6"
subtle = { version = "2.2", default-features = false, features = ["nightly"] }
@@ -23,7 +24,7 @@ subtle = { version = "2.2", default-features = false, features = ["nightly"] }
debug_allocations = ["lang_items/debug_allocations"]
debug_ctap = ["crypto/derive_debug", "libtock_drivers/debug_ctap"]
panic_console = ["lang_items/panic_console"]
std = ["cbor/std", "crypto/std", "crypto/derive_debug", "lang_items/std"]
std = ["cbor/std", "crypto/std", "crypto/derive_debug", "lang_items/std", "persistent_store/std"]
ram_storage = []
verbose = ["debug_ctap", "libtock_drivers/verbose_usb"]
with_ctap1 = ["crypto/with_ctap1"]

2
src/ctap/mod.rs
View File

@@ -500,7 +500,7 @@ where
let (signature, x5c) = match self.persistent_store.attestation_private_key()? {
Some(attestation_private_key) => {
let attestation_key =
crypto::ecdsa::SecKey::from_bytes(attestation_private_key).unwrap();
crypto::ecdsa::SecKey::from_bytes(&attestation_private_key).unwrap();
let attestation_certificate = self
.persistent_store
.attestation_certificate()?

12
src/ctap/status_code.rs
View File

@@ -81,5 +81,17 @@ pub enum Ctap2StatusCode {
/// This type of error is unexpected and the current state is undefined.
CTAP2_ERR_VENDOR_INTERNAL_ERROR = 0xF2,
/// The persistent storage invariant is broken.
///
/// There can be multiple reasons:
/// - The persistent storage has not been erased before its first usage.
/// - The persistent storage has been tempered by a third party.
/// - The flash is malfunctioning (including the Tock driver).
///
/// In the first 2 cases the persistent storage should be completely erased. If the error
/// reproduces, it may indicate a software bug or a hardware deficiency. In both cases, the
/// error should be reported.
CTAP2_ERR_VENDOR_INVALID_PERSISTENT_STORAGE = 0xF3,
CTAP2_ERR_VENDOR_LAST = 0xFF,
}

744
src/ctap/storage.rs
View File

@@ -12,13 +12,15 @@
// See the License for the specific language governing permissions and
// limitations under the License.
mod key;
#[cfg(feature = "with_ctap2_1")]
use crate::ctap::data_formats::{extract_array, extract_text_string};
use crate::ctap::data_formats::{CredentialProtectionPolicy, PublicKeyCredentialSource};
use crate::ctap::pin_protocol_v1::PIN_AUTH_LENGTH;
use crate::ctap::status_code::Ctap2StatusCode;
use crate::ctap::{key_material, USE_BATCH_ATTESTATION};
use crate::embedded_flash::{self, StoreConfig, StoreEntry, StoreError};
#[cfg(feature = "with_ctap2_1")]
use alloc::string::String;
#[cfg(any(test, feature = "ram_storage", feature = "with_ctap2_1"))]
use alloc::vec;
@@ -30,16 +32,16 @@ use core::convert::TryInto;
use crypto::rng256::Rng256;
#[cfg(any(test, feature = "ram_storage"))]
type Storage = embedded_flash::BufferStorage;
type Storage = persistent_store::BufferStorage;
#[cfg(not(any(test, feature = "ram_storage")))]
type Storage = embedded_flash::SyscallStorage;
type Storage = crate::embedded_flash::SyscallStorage;
// Those constants may be modified before compilation to tune the behavior of the key.
//
// The number of pages should be at least 2 and at most what the flash can hold. There should be no
// reason to put a small number here, except that the latency of flash operations depends on the
// number of pages. This will improve in the future. Currently, using 20 pages gives 65ms per
// operation. The rule of thumb is 3.5ms per additional page.
// The number of pages should be at least 3 and at most what the flash can hold. There should be no
// reason to put a small number here, except that the latency of flash operations is linear in the
// number of pages. This may improve in the future. Currently, using 20 pages gives between 20ms and
// 240ms per operation. The rule of thumb is between 1ms and 12ms per additional page.
//
// Limiting the number of residential keys permits to ensure a minimum number of counter increments.
// Let:
@@ -49,32 +51,15 @@ type Storage = embedded_flash::SyscallStorage;
// - C the number of erase cycles (10000)
// - I the minimum number of counter increments
//
// We have: I = ((P - 1) * 4092 - K * S) / 12 * C
// We have: I = (P * 4084 - 5107 - K * S) / 8 * C
//
// With P=20 and K=150, we have I > 2M which is enough for 500 increments per day for 10 years.
// With P=20 and K=150, we have I=2M which is enough for 500 increments per day for 10 years.
#[cfg(feature = "ram_storage")]
const NUM_PAGES: usize = 2;
const NUM_PAGES: usize = 3;
#[cfg(not(feature = "ram_storage"))]
const NUM_PAGES: usize = 20;
const MAX_SUPPORTED_RESIDENTIAL_KEYS: usize = 150;
// List of tags. They should all be unique. And there should be less than NUM_TAGS.
const TAG_CREDENTIAL: usize = 0;
const GLOBAL_SIGNATURE_COUNTER: usize = 1;
const MASTER_KEYS: usize = 2;
const PIN_HASH: usize = 3;
const PIN_RETRIES: usize = 4;
const ATTESTATION_PRIVATE_KEY: usize = 5;
const ATTESTATION_CERTIFICATE: usize = 6;
const AAGUID: usize = 7;
#[cfg(feature = "with_ctap2_1")]
const MIN_PIN_LENGTH: usize = 8;
#[cfg(feature = "with_ctap2_1")]
const MIN_PIN_LENGTH_RP_IDS: usize = 9;
// Different NUM_TAGS depending on the CTAP version make the storage incompatible,
// so we use the maximum.
const NUM_TAGS: usize = 10;
const MAX_PIN_RETRIES: u8 = 8;
const ATTESTATION_PRIVATE_KEY_LENGTH: usize = 32;
const AAGUID_LENGTH: usize = 16;
@@ -88,92 +73,18 @@ const _DEFAULT_MIN_PIN_LENGTH_RP_IDS: Vec<String> = Vec::new();
#[cfg(feature = "with_ctap2_1")]
const _MAX_RP_IDS_LENGTH: usize = 8;
#[allow(clippy::enum_variant_names)]
#[derive(PartialEq, Eq, PartialOrd, Ord)]
enum Key {
// TODO(cretin): Test whether this doesn't consume too much memory. Otherwise, we can use less
// keys. Either only a simple enum value for all credentials, or group by rp_id.
Credential {
rp_id: Option<String>,
credential_id: Option<Vec<u8>>,
user_handle: Option<Vec<u8>>,
},
GlobalSignatureCounter,
MasterKeys,
PinHash,
PinRetries,
AttestationPrivateKey,
AttestationCertificate,
Aaguid,
#[cfg(feature = "with_ctap2_1")]
MinPinLength,
#[cfg(feature = "with_ctap2_1")]
MinPinLengthRpIds,
}
/// Wrapper for master keys.
pub struct MasterKeys {
/// Master encryption key.
pub encryption: [u8; 32],
/// Master hmac key.
pub hmac: [u8; 32],
}
struct Config;
impl StoreConfig for Config {
type Key = Key;
fn num_tags(&self) -> usize {
NUM_TAGS
}
fn keys(&self, entry: StoreEntry, mut add: impl FnMut(Key)) {
match entry.tag {
TAG_CREDENTIAL => {
let credential = match deserialize_credential(entry.data) {
None => {
debug_assert!(false);
return;
}
Some(credential) => credential,
};
add(Key::Credential {
rp_id: Some(credential.rp_id.clone()),
credential_id: Some(credential.credential_id),
user_handle: None,
});
add(Key::Credential {
rp_id: Some(credential.rp_id.clone()),
credential_id: None,
user_handle: None,
});
add(Key::Credential {
rp_id: Some(credential.rp_id),
credential_id: None,
user_handle: Some(credential.user_handle),
});
add(Key::Credential {
rp_id: None,
credential_id: None,
user_handle: None,
});
}
GLOBAL_SIGNATURE_COUNTER => add(Key::GlobalSignatureCounter),
MASTER_KEYS => add(Key::MasterKeys),
PIN_HASH => add(Key::PinHash),
PIN_RETRIES => add(Key::PinRetries),
ATTESTATION_PRIVATE_KEY => add(Key::AttestationPrivateKey),
ATTESTATION_CERTIFICATE => add(Key::AttestationCertificate),
AAGUID => add(Key::Aaguid),
#[cfg(feature = "with_ctap2_1")]
MIN_PIN_LENGTH => add(Key::MinPinLength),
#[cfg(feature = "with_ctap2_1")]
MIN_PIN_LENGTH_RP_IDS => add(Key::MinPinLengthRpIds),
_ => debug_assert!(false),
}
}
}
/// CTAP persistent storage.
pub struct PersistentStore {
store: embedded_flash::Store<Storage, Config>,
store: persistent_store::Store<Storage>,
}
impl PersistentStore {
@@ -188,17 +99,19 @@ impl PersistentStore {
#[cfg(any(test, feature = "ram_storage"))]
let storage = PersistentStore::new_test_storage();
let mut store = PersistentStore {
store: embedded_flash::Store::new(storage, Config).unwrap(),
store: persistent_store::Store::new(storage).ok().unwrap(),
};
store.init(rng);
store.init(rng).unwrap();
store
}
/// Creates a syscall storage in flash.
#[cfg(not(any(test, feature = "ram_storage")))]
fn new_prod_storage() -> Storage {
Storage::new(NUM_PAGES).unwrap()
}
/// Creates a buffer storage in RAM.
#[cfg(any(test, feature = "ram_storage"))]
fn new_test_storage() -> Storage {
#[cfg(not(test))]
@@ -206,7 +119,7 @@ impl PersistentStore {
#[cfg(test)]
const PAGE_SIZE: usize = 0x1000;
let store = vec![0xff; NUM_PAGES * PAGE_SIZE].into_boxed_slice();
let options = embedded_flash::BufferOptions {
let options = persistent_store::BufferOptions {
word_size: 4,
page_size: PAGE_SIZE,
max_word_writes: 2,
@@ -216,283 +129,265 @@ impl PersistentStore {
Storage::new(store, options)
}
fn init(&mut self, rng: &mut impl Rng256) {
if self.store.find_one(&Key::MasterKeys).is_none() {
/// Initializes the store by creating missing objects.
fn init(&mut self, rng: &mut impl Rng256) -> Result<(), Ctap2StatusCode> {
// Generate and store the master keys if they are missing.
if self.store.find_handle(key::MASTER_KEYS)?.is_none() {
let master_encryption_key = rng.gen_uniform_u8x32();
let master_hmac_key = rng.gen_uniform_u8x32();
let mut master_keys = Vec::with_capacity(64);
master_keys.extend_from_slice(&master_encryption_key);
master_keys.extend_from_slice(&master_hmac_key);
self.store
.insert(StoreEntry {
tag: MASTER_KEYS,
data: &master_keys,
sensitive: true,
})
.unwrap();
self.store.insert(key::MASTER_KEYS, &master_keys)?;
}
// The following 3 entries are meant to be written by vendor-specific commands.
if USE_BATCH_ATTESTATION {
if self.store.find_one(&Key::AttestationPrivateKey).is_none() {
self.set_attestation_private_key(key_material::ATTESTATION_PRIVATE_KEY)
.unwrap();
if self
.store
.find_handle(key::ATTESTATION_PRIVATE_KEY)?
.is_none()
{
self.set_attestation_private_key(key_material::ATTESTATION_PRIVATE_KEY)?;
}
if self.store.find_one(&Key::AttestationCertificate).is_none() {
self.set_attestation_certificate(key_material::ATTESTATION_CERTIFICATE)
.unwrap();
if self
.store
.find_handle(key::ATTESTATION_CERTIFICATE)?
.is_none()
{
self.set_attestation_certificate(key_material::ATTESTATION_CERTIFICATE)?;
}
}
if self.store.find_one(&Key::Aaguid).is_none() {
self.set_aaguid(key_material::AAGUID).unwrap();
if self.store.find_handle(key::AAGUID)?.is_none() {
self.set_aaguid(key_material::AAGUID)?;
}
Ok(())
}
/// Returns the first matching credential.
///
/// Returns `None` if no credentials are matched or if `check_cred_protect` is set and the first
/// matched credential requires user verification.
pub fn find_credential(
&self,
rp_id: &str,
credential_id: &[u8],
check_cred_protect: bool,
) -> Result<Option<PublicKeyCredentialSource>, Ctap2StatusCode> {
let key = Key::Credential {
rp_id: Some(rp_id.into()),
credential_id: Some(credential_id.into()),
user_handle: None,
};
let entry = match self.store.find_one(&key) {
None => return Ok(None),
Some((_, entry)) => entry,
};
debug_assert_eq!(entry.tag, TAG_CREDENTIAL);
let result = deserialize_credential(entry.data);
debug_assert!(result.is_some());
let user_verification_required = result.as_ref().map_or(false, |cred| {
cred.cred_protect_policy == Some(CredentialProtectionPolicy::UserVerificationRequired)
let mut iter_result = Ok(());
let iter = self.iter_credentials(&mut iter_result)?;
// TODO(reviewer): Should we return an error if we find more than one matching credential?
// We did not use to in the previous version (panic in debug mode, nothing in release mode)
// but I don't remember why. Let's document it.
let result = iter.map(|(_, credential)| credential).find(|credential| {
credential.rp_id == rp_id && credential.credential_id == credential_id
});
if check_cred_protect && user_verification_required {
Ok(None)
} else {
Ok(result)
iter_result?;
if let Some(cred) = &result {
let user_verification_required = cred.cred_protect_policy
== Some(CredentialProtectionPolicy::UserVerificationRequired);
if check_cred_protect && user_verification_required {
return Ok(None);
}
}
Ok(result)
}
/// Stores or updates a credential.
///
/// If a credential with the same RP id and user handle already exists, it is replaced.
pub fn store_credential(
&mut self,
credential: PublicKeyCredentialSource,
new_credential: PublicKeyCredentialSource,
) -> Result<(), Ctap2StatusCode> {
let key = Key::Credential {
rp_id: Some(credential.rp_id.clone()),
credential_id: None,
user_handle: Some(credential.user_handle.clone()),
};
let old_entry = self.store.find_one(&key);
if old_entry.is_none() && self.count_credentials()? >= MAX_SUPPORTED_RESIDENTIAL_KEYS {
// Holds the key of the existing credential if this is an update.
let mut old_key = None;
// Holds the unordered list of used keys.
let mut keys = Vec::new();
let mut iter_result = Ok(());
let iter = self.iter_credentials(&mut iter_result)?;
for (key, credential) in iter {
keys.push(key);
if credential.rp_id == new_credential.rp_id
&& credential.user_handle == new_credential.user_handle
{
if old_key.is_some() {
return Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INVALID_PERSISTENT_STORAGE);
}
old_key = Some(key);
}
}
iter_result?;
if old_key.is_none() && keys.len() >= MAX_SUPPORTED_RESIDENTIAL_KEYS {
return Err(Ctap2StatusCode::CTAP2_ERR_KEY_STORE_FULL);
}
let credential = serialize_credential(credential)?;
let new_entry = StoreEntry {
tag: TAG_CREDENTIAL,
data: &credential,
sensitive: true,
};
match old_entry {
None => self.store.insert(new_entry)?,
Some((index, old_entry)) => {
debug_assert_eq!(old_entry.tag, TAG_CREDENTIAL);
self.store.replace(index, new_entry)?
}
let key = match old_key {
// This is a new credential being added, we need to allocate a free key. We choose the
// first available key. This is quadratic in the number of existing keys.
None => key::CREDENTIALS
.take(MAX_SUPPORTED_RESIDENTIAL_KEYS)
.find(|key| !keys.contains(key))
.ok_or(Ctap2StatusCode::CTAP2_ERR_VENDOR_INVALID_PERSISTENT_STORAGE)?,
// This is an existing credential being updated, we reuse its key.
Some(x) => x,
};
let value = serialize_credential(new_credential)?;
self.store.insert(key, &value)?;
Ok(())
}
/// Returns the list of matching credentials.
///
/// Does not return credentials that are not discoverable if `check_cred_protect` is set.
pub fn filter_credential(
&self,
rp_id: &str,
check_cred_protect: bool,
) -> Result<Vec<PublicKeyCredentialSource>, Ctap2StatusCode> {
Ok(self
.store
.find_all(&Key::Credential {
rp_id: Some(rp_id.into()),
credential_id: None,
user_handle: None,
})
.filter_map(|(_, entry)| {
debug_assert_eq!(entry.tag, TAG_CREDENTIAL);
let credential = deserialize_credential(entry.data);
debug_assert!(credential.is_some());
credential
let mut iter_result = Ok(());
let iter = self.iter_credentials(&mut iter_result)?;
let result = iter
.filter_map(|(_, credential)| {
if credential.rp_id == rp_id {
Some(credential)
} else {
None
}
})
.filter(|cred| !check_cred_protect || cred.is_discoverable())
.collect())
.collect();
iter_result?;
Ok(result)
}
/// Returns the number of credentials.
#[cfg(test)]
pub fn count_credentials(&self) -> Result<usize, Ctap2StatusCode> {
Ok(self
.store
.find_all(&Key::Credential {
rp_id: None,
credential_id: None,
user_handle: None,
})
.count())
let mut iter_result = Ok(());
let iter = self.iter_credentials(&mut iter_result)?;
let result = iter.count();
iter_result?;
Ok(result)
}
/// Iterates through the credentials.
///
/// If an error is encountered during iteration, it is written to `result`.
fn iter_credentials<'a>(
&'a self,
result: &'a mut Result<(), Ctap2StatusCode>,
) -> Result<IterCredentials<'a>, Ctap2StatusCode> {
IterCredentials::new(&self.store, result)
}
/// Returns the global signature counter.
pub fn global_signature_counter(&self) -> Result<u32, Ctap2StatusCode> {
Ok(self
.store
.find_one(&Key::GlobalSignatureCounter)
.map_or(0, |(_, entry)| {
u32::from_ne_bytes(*array_ref!(entry.data, 0, 4))
}))
}
pub fn incr_global_signature_counter(&mut self) -> Result<(), Ctap2StatusCode> {
let mut buffer = [0; core::mem::size_of::<u32>()];
match self.store.find_one(&Key::GlobalSignatureCounter) {
None => {
buffer.copy_from_slice(&1u32.to_ne_bytes());
self.store.insert(StoreEntry {
tag: GLOBAL_SIGNATURE_COUNTER,
data: &buffer,
sensitive: false,
})?;
}
Some((index, entry)) => {
let value = u32::from_ne_bytes(*array_ref!(entry.data, 0, 4));
// In hopes that servers handle the wrapping gracefully.
buffer.copy_from_slice(&value.wrapping_add(1).to_ne_bytes());
self.store.replace(
index,
StoreEntry {
tag: GLOBAL_SIGNATURE_COUNTER,
data: &buffer,
sensitive: false,
},
)?;
}
}
Ok(())
}
pub fn master_keys(&self) -> Result<MasterKeys, Ctap2StatusCode> {
let (_, entry) = self.store.find_one(&Key::MasterKeys).unwrap();
if entry.data.len() != 64 {
return Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INTERNAL_ERROR);
}
Ok(MasterKeys {
encryption: *array_ref![entry.data, 0, 32],
hmac: *array_ref![entry.data, 32, 32],
Ok(match self.store.find(key::GLOBAL_SIGNATURE_COUNTER)? {
None => 0,
Some(value) => u32::from_ne_bytes(*array_ref!(&value, 0, 4)),
})
}
pub fn pin_hash(&self) -> Result<Option<[u8; PIN_AUTH_LENGTH]>, Ctap2StatusCode> {
let data = match self.store.find_one(&Key::PinHash) {
None => return Ok(None),
Some((_, entry)) => entry.data,
};
if data.len() != PIN_AUTH_LENGTH {
return Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INTERNAL_ERROR);
}
Ok(Some(*array_ref![data, 0, PIN_AUTH_LENGTH]))
/// Increments the global signature counter.
pub fn incr_global_signature_counter(&mut self) -> Result<(), Ctap2StatusCode> {
let old_value = self.global_signature_counter()?;
// In hopes that servers handle the wrapping gracefully.
let new_value = old_value.wrapping_add(1);
self.store
.insert(key::GLOBAL_SIGNATURE_COUNTER, &new_value.to_ne_bytes())?;
Ok(())
}
/// Returns the master keys.
pub fn master_keys(&self) -> Result<MasterKeys, Ctap2StatusCode> {
let master_keys = self
.store
.find(key::MASTER_KEYS)?
.ok_or(Ctap2StatusCode::CTAP2_ERR_VENDOR_INVALID_PERSISTENT_STORAGE)?;
if master_keys.len() != 64 {
return Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INVALID_PERSISTENT_STORAGE);
}
Ok(MasterKeys {
encryption: *array_ref![master_keys, 0, 32],
hmac: *array_ref![master_keys, 32, 32],
})
}
/// Returns the PIN hash if defined.
pub fn pin_hash(&self) -> Result<Option<[u8; PIN_AUTH_LENGTH]>, Ctap2StatusCode> {
let pin_hash = match self.store.find(key::PIN_HASH)? {
None => return Ok(None),
Some(pin_hash) => pin_hash,
};
if pin_hash.len() != PIN_AUTH_LENGTH {
return Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INVALID_PERSISTENT_STORAGE);
}
Ok(Some(*array_ref![pin_hash, 0, PIN_AUTH_LENGTH]))
}
/// Sets the PIN hash.
///
/// If it was already defined, it is updated.
pub fn set_pin_hash(
&mut self,
pin_hash: &[u8; PIN_AUTH_LENGTH],
) -> Result<(), Ctap2StatusCode> {
let entry = StoreEntry {
tag: PIN_HASH,
data: pin_hash,
sensitive: true,
};
match self.store.find_one(&Key::PinHash) {
None => self.store.insert(entry)?,
Some((index, _)) => self.store.replace(index, entry)?,
}
Ok(())
Ok(self.store.insert(key::PIN_HASH, pin_hash)?)
}
/// Returns the number of remaining PIN retries.
pub fn pin_retries(&self) -> Result<u8, Ctap2StatusCode> {
Ok(self
.store
.find_one(&Key::PinRetries)
.map_or(MAX_PIN_RETRIES, |(_, entry)| {
debug_assert_eq!(entry.data.len(), 1);
entry.data[0]
}))
match self.store.find(key::PIN_RETRIES)? {
None => Ok(MAX_PIN_RETRIES),
Some(value) if value.len() == 1 => Ok(value[0]),
_ => Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INVALID_PERSISTENT_STORAGE),
}
}
/// Decrements the number of remaining PIN retries.
pub fn decr_pin_retries(&mut self) -> Result<(), Ctap2StatusCode> {
match self.store.find_one(&Key::PinRetries) {
None => {
self.store.insert(StoreEntry {
tag: PIN_RETRIES,
data: &[MAX_PIN_RETRIES.saturating_sub(1)],
sensitive: false,
})?;
}
Some((index, entry)) => {
debug_assert_eq!(entry.data.len(), 1);
if entry.data[0] == 0 {
return Ok(());
}
let new_value = entry.data[0].saturating_sub(1);
self.store.replace(
index,
StoreEntry {
tag: PIN_RETRIES,
data: &[new_value],
sensitive: false,
},
)?;
}
let old_value = self.pin_retries()?;
let new_value = old_value.saturating_sub(1);
if new_value != old_value {
self.store.insert(key::PIN_RETRIES, &[new_value])?;
}
Ok(())
}
/// Resets the number of remaining PIN retries.
pub fn reset_pin_retries(&mut self) -> Result<(), Ctap2StatusCode> {
if let Some((index, _)) = self.store.find_one(&Key::PinRetries) {
self.store.delete(index)?;
}
Ok(())
Ok(self.store.remove(key::PIN_RETRIES)?)
}
/// Returns the minimum PIN length.
#[cfg(feature = "with_ctap2_1")]
pub fn min_pin_length(&self) -> Result<u8, Ctap2StatusCode> {
Ok(self
.store
.find_one(&Key::MinPinLength)
.map_or(DEFAULT_MIN_PIN_LENGTH, |(_, entry)| {
debug_assert_eq!(entry.data.len(), 1);
entry.data[0]
}))
match self.store.find(key::MIN_PIN_LENGTH)? {
None => Ok(DEFAULT_MIN_PIN_LENGTH),
Some(value) if value.len() == 1 => Ok(value[0]),
_ => Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INVALID_PERSISTENT_STORAGE),
}
}
/// Sets the minimum PIN length.
#[cfg(feature = "with_ctap2_1")]
pub fn set_min_pin_length(&mut self, min_pin_length: u8) -> Result<(), Ctap2StatusCode> {
let entry = StoreEntry {
tag: MIN_PIN_LENGTH,
data: &[min_pin_length],
sensitive: false,
};
Ok(match self.store.find_one(&Key::MinPinLength) {
None => self.store.insert(entry)?,
Some((index, _)) => self.store.replace(index, entry)?,
})
Ok(self.store.insert(key::MIN_PIN_LENGTH, &[min_pin_length])?)
}
/// TODO: Help from reviewer needed for documentation.
#[cfg(feature = "with_ctap2_1")]
pub fn _min_pin_length_rp_ids(&self) -> Result<Vec<String>, Ctap2StatusCode> {
let rp_ids = self
.store
.find_one(&Key::MinPinLengthRpIds)
.map_or(Some(_DEFAULT_MIN_PIN_LENGTH_RP_IDS), |(_, entry)| {
_deserialize_min_pin_length_rp_ids(entry.data)
.find(key::_MIN_PIN_LENGTH_RP_IDS)?
.map_or(Some(_DEFAULT_MIN_PIN_LENGTH_RP_IDS), |value| {
_deserialize_min_pin_length_rp_ids(&value)
});
debug_assert!(rp_ids.is_some());
Ok(rp_ids.unwrap_or(vec![]))
}
/// TODO: Help from reviewer needed for documentation.
#[cfg(feature = "with_ctap2_1")]
pub fn _set_min_pin_length_rp_ids(
&mut self,
@@ -507,138 +402,173 @@ impl PersistentStore {
if min_pin_length_rp_ids.len() > _MAX_RP_IDS_LENGTH {
return Err(Ctap2StatusCode::CTAP2_ERR_KEY_STORE_FULL);
}
let entry = StoreEntry {
tag: MIN_PIN_LENGTH_RP_IDS,
data: &_serialize_min_pin_length_rp_ids(min_pin_length_rp_ids)?,
sensitive: false,
};
match self.store.find_one(&Key::MinPinLengthRpIds) {
None => {
self.store.insert(entry).unwrap();
}
Some((index, _)) => {
self.store.replace(index, entry).unwrap();
}
}
Ok(())
Ok(self.store.insert(
key::_MIN_PIN_LENGTH_RP_IDS,
&_serialize_min_pin_length_rp_ids(min_pin_length_rp_ids)?,
)?)
}
/// Returns the attestation private key if defined.
pub fn attestation_private_key(
&self,
) -> Result<Option<&[u8; ATTESTATION_PRIVATE_KEY_LENGTH]>, Ctap2StatusCode> {
let data = match self.store.find_one(&Key::AttestationPrivateKey) {
None => return Ok(None),
Some((_, entry)) => entry.data,
};
if data.len() != ATTESTATION_PRIVATE_KEY_LENGTH {
return Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INTERNAL_ERROR);
) -> Result<Option<[u8; ATTESTATION_PRIVATE_KEY_LENGTH]>, Ctap2StatusCode> {
match self.store.find(key::ATTESTATION_PRIVATE_KEY)? {
None => Ok(None),
Some(key) if key.len() != ATTESTATION_PRIVATE_KEY_LENGTH => {
Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INVALID_PERSISTENT_STORAGE)
}
Some(key) => Ok(Some(*array_ref![key, 0, ATTESTATION_PRIVATE_KEY_LENGTH])),
}
Ok(Some(array_ref!(data, 0, ATTESTATION_PRIVATE_KEY_LENGTH)))
}
/// Sets the attestation private key.
///
/// If it is already defined, it is overwritten.
pub fn set_attestation_private_key(
&mut self,
attestation_private_key: &[u8; ATTESTATION_PRIVATE_KEY_LENGTH],
) -> Result<(), Ctap2StatusCode> {
let entry = StoreEntry {
tag: ATTESTATION_PRIVATE_KEY,
data: attestation_private_key,
sensitive: false,
};
match self.store.find_one(&Key::AttestationPrivateKey) {
None => self.store.insert(entry)?,
Some((index, _)) => self.store.replace(index, entry)?,
}
Ok(())
Ok(self
.store
.insert(key::ATTESTATION_PRIVATE_KEY, attestation_private_key)?)
}
/// Returns the attestation certificate if defined.
pub fn attestation_certificate(&self) -> Result<Option<Vec<u8>>, Ctap2StatusCode> {
let data = match self.store.find_one(&Key::AttestationCertificate) {
None => return Ok(None),
Some((_, entry)) => entry.data,
};
Ok(Some(data.to_vec()))
Ok(self.store.find(key::ATTESTATION_CERTIFICATE)?)
}
/// Sets the attestation certificate.
///
/// If it is already defined, it is overwritten.
pub fn set_attestation_certificate(
&mut self,
attestation_certificate: &[u8],
) -> Result<(), Ctap2StatusCode> {
let entry = StoreEntry {
tag: ATTESTATION_CERTIFICATE,
data: attestation_certificate,
sensitive: false,
};
match self.store.find_one(&Key::AttestationCertificate) {
None => self.store.insert(entry)?,
Some((index, _)) => self.store.replace(index, entry)?,
}
Ok(())
}
pub fn aaguid(&self) -> Result<[u8; AAGUID_LENGTH], Ctap2StatusCode> {
let (_, entry) = self
Ok(self
.store
.find_one(&Key::Aaguid)
.ok_or(Ctap2StatusCode::CTAP2_ERR_VENDOR_INTERNAL_ERROR)?;
let data = entry.data;
if data.len() != AAGUID_LENGTH {
return Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INTERNAL_ERROR);
}
Ok(*array_ref![data, 0, AAGUID_LENGTH])
.insert(key::ATTESTATION_CERTIFICATE, attestation_certificate)?)
}
/// Returns the AAGUID.
pub fn aaguid(&self) -> Result<[u8; AAGUID_LENGTH], Ctap2StatusCode> {
let aaguid = self
.store
.find(key::AAGUID)?
.ok_or(Ctap2StatusCode::CTAP2_ERR_VENDOR_INVALID_PERSISTENT_STORAGE)?;
if aaguid.len() != AAGUID_LENGTH {
return Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INVALID_PERSISTENT_STORAGE);
}
Ok(*array_ref![aaguid, 0, AAGUID_LENGTH])
}
/// Sets the AAGUID.
///
/// If it is already defined, it is overwritten.
pub fn set_aaguid(&mut self, aaguid: &[u8; AAGUID_LENGTH]) -> Result<(), Ctap2StatusCode> {
let entry = StoreEntry {
tag: AAGUID,
data: aaguid,
sensitive: false,
};
match self.store.find_one(&Key::Aaguid) {
None => self.store.insert(entry)?,
Some((index, _)) => self.store.replace(index, entry)?,
}
Ok(())
Ok(self.store.insert(key::AAGUID, aaguid)?)
}
/// Resets the store as for a CTAP reset.
///
/// In particular persistent entries are not reset.
pub fn reset(&mut self, rng: &mut impl Rng256) -> Result<(), Ctap2StatusCode> {
loop {
let index = {
let mut iter = self.store.iter().filter(|(_, entry)| should_reset(entry));
match iter.next() {
None => break,
Some((index, _)) => index,
}
};
self.store.delete(index)?;
}
self.init(rng);
self.store.clear(key::NUM_PERSISTENT_KEYS)?;
self.init(rng)?;
Ok(())
}
}
impl From<StoreError> for Ctap2StatusCode {
fn from(error: StoreError) -> Ctap2StatusCode {
impl From<persistent_store::StoreError> for Ctap2StatusCode {
fn from(error: persistent_store::StoreError) -> Ctap2StatusCode {
use persistent_store::StoreError::*;
match error {
StoreError::StoreFull => Ctap2StatusCode::CTAP2_ERR_KEY_STORE_FULL,
StoreError::InvalidTag => unreachable!(),
StoreError::InvalidPrecondition => unreachable!(),
// This error is expected. The store is full.
NoCapacity => Ctap2StatusCode::CTAP2_ERR_KEY_STORE_FULL,
// This error is expected. The flash is out of life.
NoLifetime => Ctap2StatusCode::CTAP2_ERR_KEY_STORE_FULL,
// This error is expected if we don't satisfy the store preconditions. For example we
// try to store a credential which is too long.
InvalidArgument => Ctap2StatusCode::CTAP2_ERR_VENDOR_INTERNAL_ERROR,
// This error is not expected. The storage has been tempered with. We could erase the
// storage.
InvalidStorage => Ctap2StatusCode::CTAP2_ERR_VENDOR_INVALID_PERSISTENT_STORAGE,
// This error is not expected. The kernel is failing our syscalls.
StorageError => Ctap2StatusCode::CTAP1_ERR_OTHER,
}
}
}
fn should_reset(entry: &StoreEntry<'_>) -> bool {
match entry.tag {
ATTESTATION_PRIVATE_KEY | ATTESTATION_CERTIFICATE | AAGUID => false,
_ => true,
/// Iterator for credentials.
struct IterCredentials<'a> {
/// The store being iterated.
store: &'a persistent_store::Store<Storage>,
/// The store iterator.
iter: persistent_store::StoreIter<'a, Storage>,
/// The iteration result.
///
/// It starts as success and gets written at most once with an error if something fails. The
/// iteration stops as soon as an error is encountered.
result: &'a mut Result<(), Ctap2StatusCode>,
}
impl<'a> IterCredentials<'a> {
/// Creates a credential iterator.
fn new(
store: &'a persistent_store::Store<Storage>,
result: &'a mut Result<(), Ctap2StatusCode>,
) -> Result<IterCredentials<'a>, Ctap2StatusCode> {
let iter = store.iter()?;
Ok(IterCredentials {
store,
iter,
result,
})
}
/// Marks the iteration as failed if the content is absent.
///
/// For convenience, the function takes and returns ownership instead of taking a shared
/// reference and returning nothing. This permits to use it in both expressions and statements
/// instead of statements only.
fn unwrap<T>(&mut self, x: Option<T>) -> Option<T> {
if x.is_none() {
*self.result = Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INVALID_PERSISTENT_STORAGE);
}
x
}
}
impl<'a> Iterator for IterCredentials<'a> {
type Item = (usize, PublicKeyCredentialSource);
fn next(&mut self) -> Option<(usize, PublicKeyCredentialSource)> {
if self.result.is_err() {
return None;
}
while let Some(next) = self.iter.next() {
let handle = self.unwrap(next.ok())?;
let key = handle.get_key();
if !key::CREDENTIALS.contains(&key) {
continue;
}
let value = self.unwrap(handle.get_value(&self.store).ok())?;
let credential = self.unwrap(deserialize_credential(&value))?;
return Some((key, credential));
}
None
}
}
/// Deserializes a credential from storage representation.
fn deserialize_credential(data: &[u8]) -> Option<PublicKeyCredentialSource> {
let cbor = cbor::read(data).ok()?;
cbor.try_into().ok()
}
/// Serializes a credential to storage representation.
fn serialize_credential(credential: PublicKeyCredentialSource) -> Result<Vec<u8>, Ctap2StatusCode> {
let mut data = Vec::new();
if cbor::write(credential.into(), &mut data) {
@@ -648,6 +578,7 @@ fn serialize_credential(credential: PublicKeyCredentialSource) -> Result<Vec<u8>
}
}
/// TODO: Help from reviewer needed for documentation.
#[cfg(feature = "with_ctap2_1")]
fn _deserialize_min_pin_length_rp_ids(data: &[u8]) -> Option<Vec<String>> {
let cbor = cbor::read(data).ok()?;
@@ -659,6 +590,7 @@ fn _deserialize_min_pin_length_rp_ids(data: &[u8]) -> Option<Vec<String>> {
.ok()
}
/// TODO: Help from reviewer needed for documentation.
#[cfg(feature = "with_ctap2_1")]
fn _serialize_min_pin_length_rp_ids(rp_ids: Vec<String>) -> Result<Vec<u8>, Ctap2StatusCode> {
let mut data = Vec::new();
@@ -693,28 +625,6 @@ mod test {
}
}
#[test]
fn format_overhead() {
// nRF52840 NVMC
const WORD_SIZE: usize = 4;
const PAGE_SIZE: usize = 0x1000;
const NUM_PAGES: usize = 100;
let store = vec![0xff; NUM_PAGES * PAGE_SIZE].into_boxed_slice();
let options = embedded_flash::BufferOptions {
word_size: WORD_SIZE,
page_size: PAGE_SIZE,
max_word_writes: 2,
max_page_erases: 10000,
strict_write: true,
};
let storage = Storage::new(store, options);
let store = embedded_flash::Store::new(storage, Config).unwrap();
// We can replace 3 bytes with minimal overhead.
assert_eq!(store.replace_len(false, 0), 2 * WORD_SIZE);
assert_eq!(store.replace_len(false, 3), 3 * WORD_SIZE);
assert_eq!(store.replace_len(false, 4), 3 * WORD_SIZE);
}
#[test]
fn test_store() {
let mut rng = ThreadRng256 {};
@@ -974,21 +884,21 @@ mod test {
let mut persistent_store = PersistentStore::new(&mut rng);
// The pin retries is initially at the maximum.
assert_eq!(persistent_store.pin_retries().unwrap(), MAX_PIN_RETRIES);
assert_eq!(persistent_store.pin_retries(), Ok(MAX_PIN_RETRIES));
// Decrementing the pin retries decrements the pin retries.
for pin_retries in (0..MAX_PIN_RETRIES).rev() {
persistent_store.decr_pin_retries().unwrap();
assert_eq!(persistent_store.pin_retries().unwrap(), pin_retries);
assert_eq!(persistent_store.pin_retries(), Ok(pin_retries));
}
// Decrementing the pin retries after zero does not modify the pin retries.
persistent_store.decr_pin_retries().unwrap();
assert_eq!(persistent_store.pin_retries().unwrap(), 0);
assert_eq!(persistent_store.pin_retries(), Ok(0));
// Resetting the pin retries resets the pin retries.
persistent_store.reset_pin_retries().unwrap();
assert_eq!(persistent_store.pin_retries().unwrap(), MAX_PIN_RETRIES);
assert_eq!(persistent_store.pin_retries(), Ok(MAX_PIN_RETRIES));
}
#[test]
@@ -1018,7 +928,7 @@ mod test {
// The persistent keys stay initialized and preserve their value after a reset.
persistent_store.reset(&mut rng).unwrap();
assert_eq!(
persistent_store.attestation_private_key().unwrap().unwrap(),
&persistent_store.attestation_private_key().unwrap().unwrap(),
key_material::ATTESTATION_PRIVATE_KEY
);
assert_eq!(

135
src/ctap/storage/key.rs Normal file
View File

@@ -0,0 +1,135 @@
// Copyright 2019-2020 Google LLC
//
// 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.
/// Number of keys that persist the CTAP reset command.
pub const NUM_PERSISTENT_KEYS: usize = 20;
/// Defines a key given its name and value or range of values.
macro_rules! make_key {
($(#[$doc: meta])* $name: ident = $key: literal..$end: literal) => {
$(#[$doc])* pub const $name: core::ops::Range<usize> = $key..$end;
};
($(#[$doc: meta])* $name: ident = $key: literal) => {
$(#[$doc])* pub const $name: usize = $key;
};
}
/// Returns the range of values of a key given its value description.
#[cfg(test)]
macro_rules! make_range {
($key: literal..$end: literal) => {
$key..$end
};
($key: literal) => {
$key..$key + 1
};
}
/// Helper to define keys as a partial partition of a range.
macro_rules! make_partition {
($range: expr,
$(
$(#[$doc: meta])*
$name: ident = $key: literal $(.. $end: literal)?;
)*) => {
$(
make_key!($(#[$doc])* $name = $key $(.. $end)?);
)*
#[cfg(test)]
const KEY_RANGE: core::ops::Range<usize> = $range;
#[cfg(test)]
const ALL_KEYS: &[core::ops::Range<usize>] = &[$(make_range!($key $(.. $end)?)),*];
};
}
make_partition! {
// We reserve 0 and 2048+ for possible migration purposes. We add persistent entries starting
// from 1 and going up. We add non-persistent entries starting from 2047 and going down. This
// way, we don't commit to a fixed number of persistent keys.
1..2048,
// WARNING: Keys should not be deleted but prefixed with `_` to avoid accidentally reusing them.
/// The attestation private key.
ATTESTATION_PRIVATE_KEY = 1;
/// The attestation certificate.
ATTESTATION_CERTIFICATE = 2;
/// The aaguid.
AAGUID = 3;
// This is the persistent key limit:
// - When adding a (persistent) key above this message, make sure its value is smaller than
// NUM_PERSISTENT_KEYS.
// - When adding a (non-persistent) key below this message, make sure its value is bigger or
// equal than NUM_PERSISTENT_KEYS.
/// The credentials.
///
/// Depending on `MAX_SUPPORTED_RESIDENTIAL_KEYS`, only a prefix of those keys is used. Each
/// board may configure `MAX_SUPPORTED_RESIDENTIAL_KEYS` depending on the storage size.
CREDENTIALS = 1700..2000;
/// TODO: Help from reviewer needed for documentation.
_MIN_PIN_LENGTH_RP_IDS = 2042;
/// The minimum PIN length.
#[cfg(feature = "with_ctap2_1")]
MIN_PIN_LENGTH = 2043;
/// The number of PIN retries.
///
/// If the entry is absent, the number of PIN retries is `MAX_PIN_RETRIES`.
PIN_RETRIES = 2044;
/// The PIN hash.
///
/// If the entry is absent, there is no PIN set.
PIN_HASH = 2045;
/// The encryption and hmac keys.
///
/// This entry is always present. It is generated at startup if absent. This is not a persistent
/// key because its value should change after a CTAP reset.
MASTER_KEYS = 2046;
/// The global signature counter.
///
/// If the entry is absent, the counter is 0.
GLOBAL_SIGNATURE_COUNTER = 2047;
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn enough_credentials() {
use super::super::MAX_SUPPORTED_RESIDENTIAL_KEYS;
assert!(MAX_SUPPORTED_RESIDENTIAL_KEYS <= CREDENTIALS.end - CREDENTIALS.start);
}
#[test]
fn keys_are_disjoint() {
// Check that keys are in the range.
for keys in ALL_KEYS {
assert!(KEY_RANGE.start <= keys.start && keys.end <= KEY_RANGE.end);
}
// Check that keys are assigned at most once, essentially partitioning the range.
for key in KEY_RANGE {
assert!(ALL_KEYS.iter().filter(|keys| keys.contains(&key)).count() <= 1);
}
}
}

457
src/embedded_flash/buffer.rs
View File

@@ -1,457 +0,0 @@
// Copyright 2019 Google LLC
//
// 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.
use super::{Index, Storage, StorageError, StorageResult};
use alloc::boxed::Box;
use alloc::vec;
pub struct BufferStorage {
storage: Box<[u8]>,
options: BufferOptions,
word_writes: Box<[usize]>,
page_erases: Box<[usize]>,
snapshot: Snapshot,
}
#[derive(Copy, Clone, Debug)]
pub struct BufferOptions {
/// Size of a word in bytes.
pub word_size: usize,
/// Size of a page in bytes.
pub page_size: usize,
/// How many times a word can be written between page erasures
pub max_word_writes: usize,
/// How many times a page can be erased.
pub max_page_erases: usize,
/// Bits cannot be written from 0 to 1.
pub strict_write: bool,
}
impl BufferStorage {
/// Creates a fake embedded flash using a buffer.
///
/// This implementation checks that no words are written more than `max_word_writes` between
/// page erasures and than no pages are erased more than `max_page_erases`. If `strict_write` is
/// true, it also checks that no bits are written from 0 to 1. It also permits to take snapshots
/// of the storage during write and erase operations (although words would still be written or
/// erased completely).
///
/// # Panics
///
/// The following preconditions must hold:
/// - `options.word_size` must be a power of two.
/// - `options.page_size` must be a power of two.
/// - `options.page_size` must be word-aligned.
/// - `storage.len()` must be page-aligned.
pub fn new(storage: Box<[u8]>, options: BufferOptions) -> BufferStorage {
assert!(options.word_size.is_power_of_two());
assert!(options.page_size.is_power_of_two());
let num_words = storage.len() / options.word_size;
let num_pages = storage.len() / options.page_size;
let buffer = BufferStorage {
storage,
options,
word_writes: vec![0; num_words].into_boxed_slice(),
page_erases: vec![0; num_pages].into_boxed_slice(),
snapshot: Snapshot::Ready,
};
assert!(buffer.is_word_aligned(buffer.options.page_size));
assert!(buffer.is_page_aligned(buffer.storage.len()));
buffer
}
/// Takes a snapshot of the storage after a given amount of word operations.
///
/// Each time a word is written or erased, the delay is decremented if positive. Otherwise, a
/// snapshot is taken before the operation is executed.
///
/// # Panics
///
/// Panics if a snapshot has been armed and not examined.
pub fn arm_snapshot(&mut self, delay: usize) {
self.snapshot.arm(delay);
}
/// Unarms and returns the snapshot or the delay remaining.
///
/// # Panics
///
/// Panics if a snapshot was not armed.
pub fn get_snapshot(&mut self) -> Result<Box<[u8]>, usize> {
self.snapshot.get()
}
/// Takes a snapshot of the storage.
pub fn take_snapshot(&self) -> Box<[u8]> {
self.storage.clone()
}
/// Returns the storage.
pub fn get_storage(self) -> Box<[u8]> {
self.storage
}
fn is_word_aligned(&self, x: usize) -> bool {
x & (self.options.word_size - 1) == 0
}
fn is_page_aligned(&self, x: usize) -> bool {
x & (self.options.page_size - 1) == 0
}
/// Writes a slice to the storage.
///
/// The slice `value` is written to `index`. The `erase` boolean specifies whether this is an
/// erase operation or a write operation which matters for the checks and updating the shadow
/// storage. This also takes a snapshot of the storage if a snapshot was armed and the delay has
/// elapsed.
///
/// The following preconditions should hold:
/// - `index` is word-aligned.
/// - `value.len()` is word-aligned.
///
/// The following checks are performed:
/// - The region of length `value.len()` starting at `index` fits in a storage page.
/// - A word is not written more than `max_word_writes`.
/// - A page is not erased more than `max_page_erases`.
/// - The new word only switches 1s to 0s (only if `strict_write` is set).
fn update_storage(&mut self, index: Index, value: &[u8], erase: bool) -> StorageResult<()> {
debug_assert!(self.is_word_aligned(index.byte) && self.is_word_aligned(value.len()));
let dst = index.range(value.len(), self)?.step_by(self.word_size());
let src = value.chunks(self.word_size());
// Check and update page shadow.
if erase {
let page = index.page;
assert!(self.page_erases[page] < self.max_page_erases());
self.page_erases[page] += 1;
}
for (byte, val) in dst.zip(src) {
let range = byte..byte + self.word_size();
// The driver doesn't write identical words.
if &self.storage[range.clone()] == val {
continue;
}
// Check and update word shadow.
let word = byte / self.word_size();
if erase {
self.word_writes[word] = 0;
} else {
assert!(self.word_writes[word] < self.max_word_writes());
self.word_writes[word] += 1;
}
// Check strict write.
if !erase && self.options.strict_write {
for (byte, &val) in range.clone().zip(val) {
assert_eq!(self.storage[byte] & val, val);
}
}
// Take snapshot if armed and delay expired.
self.snapshot.take(&self.storage);
// Write storage
self.storage[range].copy_from_slice(val);
}
Ok(())
}
}
impl Storage for BufferStorage {
fn word_size(&self) -> usize {
self.options.word_size
}
fn page_size(&self) -> usize {
self.options.page_size
}
fn num_pages(&self) -> usize {
self.storage.len() / self.options.page_size
}
fn max_word_writes(&self) -> usize {
self.options.max_word_writes
}
fn max_page_erases(&self) -> usize {
self.options.max_page_erases
}
fn read_slice(&self, index: Index, length: usize) -> StorageResult<&[u8]> {
Ok(&self.storage[index.range(length, self)?])
}
fn write_slice(&mut self, index: Index, value: &[u8]) -> StorageResult<()> {
if !self.is_word_aligned(index.byte) || !self.is_word_aligned(value.len()) {
return Err(StorageError::NotAligned);
}
self.update_storage(index, value, false)
}
fn erase_page(&mut self, page: usize) -> StorageResult<()> {
let index = Index { page, byte: 0 };
let value = vec![0xff; self.page_size()];
self.update_storage(index, &value, true)
}
}
// Controls when a snapshot of the storage is taken.
//
// This can be used to simulate power-offs while the device is writing to the storage or erasing a
// page in the storage.
enum Snapshot {
// Mutable word operations have normal behavior.
Ready,
// If the delay is positive, mutable word operations decrement it. If the count is zero, mutable
// word operations take a snapshot of the storage.
Armed { delay: usize },
// Mutable word operations have normal behavior.
Taken { storage: Box<[u8]> },
}
impl Snapshot {
fn arm(&mut self, delay: usize) {
match self {
Snapshot::Ready => *self = Snapshot::Armed { delay },
_ => panic!(),
}
}
fn get(&mut self) -> Result<Box<[u8]>, usize> {
let mut snapshot = Snapshot::Ready;
core::mem::swap(self, &mut snapshot);
match snapshot {
Snapshot::Armed { delay } => Err(delay),
Snapshot::Taken { storage } => Ok(storage),
_ => panic!(),
}
}
fn take(&mut self, storage: &[u8]) {
if let Snapshot::Armed { delay } = self {
if *delay == 0 {
let storage = storage.to_vec().into_boxed_slice();
*self = Snapshot::Taken { storage };
} else {
*delay -= 1;
}
}
}
}
#[cfg(test)]
mod tests {
use super::*;
const NUM_PAGES: usize = 2;
const OPTIONS: BufferOptions = BufferOptions {
word_size: 4,
page_size: 16,
max_word_writes: 2,
max_page_erases: 3,
strict_write: true,
};
// Those words are decreasing bit patterns. Bits are only changed from 1 to 0 and at last one
// bit is changed.
const BLANK_WORD: &[u8] = &[0xff, 0xff, 0xff, 0xff];
const FIRST_WORD: &[u8] = &[0xee, 0xdd, 0xbb, 0x77];
const SECOND_WORD: &[u8] = &[0xca, 0xc9, 0xa9, 0x65];
const THIRD_WORD: &[u8] = &[0x88, 0x88, 0x88, 0x44];
fn new_storage() -> Box<[u8]> {
vec![0xff; NUM_PAGES * OPTIONS.page_size].into_boxed_slice()
}
#[test]
fn words_are_decreasing() {
fn assert_is_decreasing(prev: &[u8], next: &[u8]) {
for (&prev, &next) in prev.iter().zip(next.iter()) {
assert_eq!(prev & next, next);
assert!(prev != next);
}
}
assert_is_decreasing(BLANK_WORD, FIRST_WORD);
assert_is_decreasing(FIRST_WORD, SECOND_WORD);
assert_is_decreasing(SECOND_WORD, THIRD_WORD);
}
#[test]
fn options_ok() {
let buffer = BufferStorage::new(new_storage(), OPTIONS);
assert_eq!(buffer.word_size(), OPTIONS.word_size);
assert_eq!(buffer.page_size(), OPTIONS.page_size);
assert_eq!(buffer.num_pages(), NUM_PAGES);
assert_eq!(buffer.max_word_writes(), OPTIONS.max_word_writes);
assert_eq!(buffer.max_page_erases(), OPTIONS.max_page_erases);
}
#[test]
fn read_write_ok() {
let mut buffer = BufferStorage::new(new_storage(), OPTIONS);
let index = Index { page: 0, byte: 0 };
let next_index = Index { page: 0, byte: 4 };
assert_eq!(buffer.read_slice(index, 4).unwrap(), BLANK_WORD);
buffer.write_slice(index, FIRST_WORD).unwrap();
assert_eq!(buffer.read_slice(index, 4).unwrap(), FIRST_WORD);
assert_eq!(buffer.read_slice(next_index, 4).unwrap(), BLANK_WORD);
}
#[test]
fn erase_ok() {
let mut buffer = BufferStorage::new(new_storage(), OPTIONS);
let index = Index { page: 0, byte: 0 };
let other_index = Index { page: 1, byte: 0 };
buffer.write_slice(index, FIRST_WORD).unwrap();
buffer.write_slice(other_index, FIRST_WORD).unwrap();
assert_eq!(buffer.read_slice(index, 4).unwrap(), FIRST_WORD);
assert_eq!(buffer.read_slice(other_index, 4).unwrap(), FIRST_WORD);
buffer.erase_page(0).unwrap();
assert_eq!(buffer.read_slice(index, 4).unwrap(), BLANK_WORD);
assert_eq!(buffer.read_slice(other_index, 4).unwrap(), FIRST_WORD);
}
#[test]
fn invalid_range() {
let mut buffer = BufferStorage::new(new_storage(), OPTIONS);
let index = Index { page: 0, byte: 12 };
let half_index = Index { page: 0, byte: 14 };
let over_index = Index { page: 0, byte: 16 };
let bad_page = Index { page: 2, byte: 0 };
// Reading a word in the storage is ok.
assert!(buffer.read_slice(index, 4).is_ok());
// Reading a half-word in the storage is ok.
assert!(buffer.read_slice(half_index, 2).is_ok());
// Reading even a single byte outside a page is not ok.
assert!(buffer.read_slice(over_index, 1).is_err());
// But reading an empty slice just after a page is ok.
assert!(buffer.read_slice(over_index, 0).is_ok());
// Reading even an empty slice outside the storage is not ok.
assert!(buffer.read_slice(bad_page, 0).is_err());
// Writing a word in the storage is ok.
assert!(buffer.write_slice(index, FIRST_WORD).is_ok());
// Writing an unaligned word is not ok.
assert!(buffer.write_slice(half_index, FIRST_WORD).is_err());
// Writing a word outside a page is not ok.
assert!(buffer.write_slice(over_index, FIRST_WORD).is_err());
// But writing an empty slice just after a page is ok.
assert!(buffer.write_slice(over_index, &[]).is_ok());
// Writing even an empty slice outside the storage is not ok.
assert!(buffer.write_slice(bad_page, &[]).is_err());
// Only pages in the storage can be erased.
assert!(buffer.erase_page(0).is_ok());
assert!(buffer.erase_page(2).is_err());
}
#[test]
fn write_twice_ok() {
let mut buffer = BufferStorage::new(new_storage(), OPTIONS);
let index = Index { page: 0, byte: 4 };
assert!(buffer.write_slice(index, FIRST_WORD).is_ok());
assert!(buffer.write_slice(index, SECOND_WORD).is_ok());
}
#[test]
fn write_twice_and_once_ok() {
let mut buffer = BufferStorage::new(new_storage(), OPTIONS);
let index = Index { page: 0, byte: 0 };
let next_index = Index { page: 0, byte: 4 };
assert!(buffer.write_slice(index, FIRST_WORD).is_ok());
assert!(buffer.write_slice(index, SECOND_WORD).is_ok());
assert!(buffer.write_slice(next_index, THIRD_WORD).is_ok());
}
#[test]
#[should_panic]
fn write_three_times_panics() {
let mut buffer = BufferStorage::new(new_storage(), OPTIONS);
let index = Index { page: 0, byte: 4 };
assert!(buffer.write_slice(index, FIRST_WORD).is_ok());
assert!(buffer.write_slice(index, SECOND_WORD).is_ok());
let _ = buffer.write_slice(index, THIRD_WORD);
}
#[test]
fn write_twice_then_once_ok() {
let mut buffer = BufferStorage::new(new_storage(), OPTIONS);
let index = Index { page: 0, byte: 0 };
assert!(buffer.write_slice(index, FIRST_WORD).is_ok());
assert!(buffer.write_slice(index, SECOND_WORD).is_ok());
assert!(buffer.erase_page(0).is_ok());
assert!(buffer.write_slice(index, FIRST_WORD).is_ok());
}
#[test]
fn erase_three_times_ok() {
let mut buffer = BufferStorage::new(new_storage(), OPTIONS);
assert!(buffer.erase_page(0).is_ok());
assert!(buffer.erase_page(0).is_ok());
assert!(buffer.erase_page(0).is_ok());
}
#[test]
fn erase_three_times_and_once_ok() {
let mut buffer = BufferStorage::new(new_storage(), OPTIONS);
assert!(buffer.erase_page(0).is_ok());
assert!(buffer.erase_page(0).is_ok());
assert!(buffer.erase_page(0).is_ok());
assert!(buffer.erase_page(1).is_ok());
}
#[test]
#[should_panic]
fn erase_four_times_panics() {
let mut buffer = BufferStorage::new(new_storage(), OPTIONS);
assert!(buffer.erase_page(0).is_ok());
assert!(buffer.erase_page(0).is_ok());
assert!(buffer.erase_page(0).is_ok());
let _ = buffer.erase_page(0).is_ok();
}
#[test]
#[should_panic]
fn switch_zero_to_one_panics() {
let mut buffer = BufferStorage::new(new_storage(), OPTIONS);
let index = Index { page: 0, byte: 0 };
assert!(buffer.write_slice(index, SECOND_WORD).is_ok());
let _ = buffer.write_slice(index, FIRST_WORD);
}
#[test]
fn get_storage_ok() {
let mut buffer = BufferStorage::new(new_storage(), OPTIONS);
let index = Index { page: 0, byte: 4 };
buffer.write_slice(index, FIRST_WORD).unwrap();
let storage = buffer.get_storage();
assert_eq!(&storage[..4], BLANK_WORD);
assert_eq!(&storage[4..8], FIRST_WORD);
}
#[test]
fn snapshot_ok() {
let mut buffer = BufferStorage::new(new_storage(), OPTIONS);
let index = Index { page: 0, byte: 0 };
let value = [FIRST_WORD, SECOND_WORD].concat();
buffer.arm_snapshot(1);
buffer.write_slice(index, &value).unwrap();
let storage = buffer.get_snapshot().unwrap();
assert_eq!(&storage[..8], &[FIRST_WORD, BLANK_WORD].concat()[..]);
let storage = buffer.take_snapshot();
assert_eq!(&storage[..8], &value[..]);
}
}

10
src/embedded_flash/mod.rs
View File

@@ -1,4 +1,4 @@
// Copyright 2019 Google LLC
// Copyright 2019-2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
@@ -12,16 +12,8 @@
// See the License for the specific language governing permissions and
// limitations under the License.
#[cfg(any(test, feature = "ram_storage"))]
mod buffer;
mod storage;
mod store;
#[cfg(not(any(test, feature = "ram_storage")))]
mod syscall;
#[cfg(any(test, feature = "ram_storage"))]
pub use self::buffer::{BufferOptions, BufferStorage};
pub use self::storage::{Index, Storage, StorageError, StorageResult};
pub use self::store::{Store, StoreConfig, StoreEntry, StoreError, StoreIndex};
#[cfg(not(any(test, feature = "ram_storage")))]
pub use self::syscall::SyscallStorage;

107
src/embedded_flash/storage.rs
View File

@@ -1,107 +0,0 @@
// Copyright 2019 Google LLC
//
// 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.
#[derive(Copy, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "std", derive(Debug))]
pub struct Index {
pub page: usize,
pub byte: usize,
}
#[derive(Debug)]
pub enum StorageError {
BadFlash,
NotAligned,
OutOfBounds,
KernelError { code: isize },
}
pub type StorageResult<T> = Result<T, StorageError>;
/// Abstraction for embedded flash storage.
pub trait Storage {
/// Returns the size of a word in bytes.
fn word_size(&self) -> usize;
/// Returns the size of a page in bytes.
fn page_size(&self) -> usize;
/// Returns the number of pages in the storage.
fn num_pages(&self) -> usize;
/// Returns how many times a word can be written between page erasures.
fn max_word_writes(&self) -> usize;
/// Returns how many times a page can be erased in the lifetime of the flash.
fn max_page_erases(&self) -> usize;
/// Reads a slice from the storage.
///
/// The slice does not need to be word-aligned.
///
/// # Errors
///
/// The `index` must designate `length` bytes in the storage.
fn read_slice(&self, index: Index, length: usize) -> StorageResult<&[u8]>;
/// Writes a word-aligned slice to the storage.
///
/// The written words should not have been written too many times since last page erasure.
///
/// # Errors
///
/// The following preconditions must hold:
/// - `index` must be word-aligned.
/// - `value.len()` must be a multiple of the word size.
/// - `index` must designate `value.len()` bytes in the storage.
/// - `value` must be in memory until [read-only allow][tock_1274] is resolved.
///
/// [tock_1274]: https://github.com/tock/tock/issues/1274.
fn write_slice(&mut self, index: Index, value: &[u8]) -> StorageResult<()>;
/// Erases a page of the storage.
///
/// # Errors
///
/// The `page` must be in the storage.
fn erase_page(&mut self, page: usize) -> StorageResult<()>;
}
impl Index {
/// Returns whether a slice fits in a storage page.
fn is_valid(self, length: usize, storage: &impl Storage) -> bool {
self.page < storage.num_pages()
&& storage
.page_size()
.checked_sub(length)
.map(|limit| self.byte <= limit)
.unwrap_or(false)
}
/// Returns the range of a valid slice.
///
/// The range starts at `self` with `length` bytes.
pub fn range(
self,
length: usize,
storage: &impl Storage,
) -> StorageResult<core::ops::Range<usize>> {
if self.is_valid(length, storage) {
let start = self.page * storage.page_size() + self.byte;
Ok(start..start + length)
} else {
Err(StorageError::OutOfBounds)
}
}
}

177
src/embedded_flash/store/bitfield.rs
View File

@@ -1,177 +0,0 @@
// Copyright 2019 Google LLC
//
// 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.
/// Defines a consecutive sequence of bits.
#[derive(Copy, Clone)]
pub struct BitRange {
/// The first bit of the sequence.
pub start: usize,
/// The length in bits of the sequence.
pub length: usize,
}
impl BitRange {
/// Returns the first bit following a bit range.
pub fn end(self) -> usize {
self.start + self.length
}
}
/// Defines a consecutive sequence of bytes.
///
/// The bits in those bytes are ignored which essentially creates a gap in a sequence of bits. The
/// gap is necessarily at byte boundaries. This is used to ignore the user data in an entry
/// essentially providing a view of the entry information (header and footer).
#[derive(Copy, Clone)]
pub struct ByteGap {
pub start: usize,
pub length: usize,
}
/// Empty gap. All bits count.
pub const NO_GAP: ByteGap = ByteGap {
start: 0,
length: 0,
};
impl ByteGap {
/// Translates a bit to skip the gap.
fn shift(self, bit: usize) -> usize {
if bit < 8 * self.start {
bit
} else {
bit + 8 * self.length
}
}
/// Returns the slice of `data` corresponding to the gap.
pub fn slice(self, data: &[u8]) -> &[u8] {
&data[self.start..self.start + self.length]
}
}
/// Returns whether a bit is set in a sequence of bits.
///
/// The sequence of bits is little-endian (both for bytes and bits) and defined by the bits that
/// are in `data` but not in `gap`.
pub fn is_zero(bit: usize, data: &[u8], gap: ByteGap) -> bool {
let bit = gap.shift(bit);
debug_assert!(bit < 8 * data.len());
data[bit / 8] & (1 << (bit % 8)) == 0
}
/// Sets a bit to zero in a sequence of bits.
///
/// The sequence of bits is little-endian (both for bytes and bits) and defined by the bits that
/// are in `data` but not in `gap`.
pub fn set_zero(bit: usize, data: &mut [u8], gap: ByteGap) {
let bit = gap.shift(bit);
debug_assert!(bit < 8 * data.len());
data[bit / 8] &= !(1 << (bit % 8));
}
/// Returns a little-endian value in a sequence of bits.
///
/// The sequence of bits is little-endian (both for bytes and bits) and defined by the bits that
/// are in `data` but not in `gap`. The range of bits where the value is stored in defined by
/// `range`. The value must fit in a `usize`.
pub fn get_range(range: BitRange, data: &[u8], gap: ByteGap) -> usize {
debug_assert!(range.length <= 8 * core::mem::size_of::<usize>());
let mut result = 0;
for i in 0..range.length {
if !is_zero(range.start + i, data, gap) {
result |= 1 << i;
}
}
result
}
/// Sets a little-endian value in a sequence of bits.
///
/// The sequence of bits is little-endian (both for bytes and bits) and defined by the bits that
/// are in `data` but not in `gap`. The range of bits where the value is stored in defined by
/// `range`. The bits set to 1 in `value` must also be set to `1` in the sequence of bits.
pub fn set_range(range: BitRange, data: &mut [u8], gap: ByteGap, value: usize) {
debug_assert!(range.length == 8 * core::mem::size_of::<usize>() || value < 1 << range.length);
for i in 0..range.length {
if value & 1 << i == 0 {
set_zero(range.start + i, data, gap);
}
}
}
/// Tests the `is_zero` and `set_zero` pair of functions.
#[test]
fn zero_ok() {
const GAP: ByteGap = ByteGap {
start: 2,
length: 1,
};
for i in 0..24 {
assert!(!is_zero(i, &[0xffu8, 0xff, 0x00, 0xff] as &[u8], GAP));
}
// Tests reading and setting a bit. The result should have all bits set to 1 except for the bit
// to test and the gap.
fn test(bit: usize, result: &[u8]) {
assert!(is_zero(bit, result, GAP));
let mut data = vec![0xff; result.len()];
// Set the gap bits to 0.
for i in 0..GAP.length {
data[GAP.start + i] = 0x00;
}
set_zero(bit, &mut data, GAP);
assert_eq!(data, result);
}
test(0, &[0xfe, 0xff, 0x00, 0xff]);
test(1, &[0xfd, 0xff, 0x00, 0xff]);
test(2, &[0xfb, 0xff, 0x00, 0xff]);
test(7, &[0x7f, 0xff, 0x00, 0xff]);
test(8, &[0xff, 0xfe, 0x00, 0xff]);
test(15, &[0xff, 0x7f, 0x00, 0xff]);
test(16, &[0xff, 0xff, 0x00, 0xfe]);
test(17, &[0xff, 0xff, 0x00, 0xfd]);
test(23, &[0xff, 0xff, 0x00, 0x7f]);
}
/// Tests the `get_range` and `set_range` pair of functions.
#[test]
fn range_ok() {
// Tests reading and setting a range. The result should have all bits set to 1 except for the
// range to test and the gap.
fn test(start: usize, length: usize, value: usize, result: &[u8], gap: ByteGap) {
let range = BitRange { start, length };
assert_eq!(get_range(range, result, gap), value);
let mut data = vec![0xff; result.len()];
for i in 0..gap.length {
data[gap.start + i] = 0x00;
}
set_range(range, &mut data, gap, value);
assert_eq!(data, result);
}
test(0, 8, 42, &[42], NO_GAP);
test(3, 12, 0b11_0101, &[0b1010_1111, 0b1000_0001], NO_GAP);
test(0, 16, 0x1234, &[0x34, 0x12], NO_GAP);
test(4, 16, 0x1234, &[0x4f, 0x23, 0xf1], NO_GAP);
let mut gap = ByteGap {
start: 1,
length: 1,
};
test(3, 12, 0b11_0101, &[0b1010_1111, 0x00, 0b1000_0001], gap);
gap.length = 2;
test(0, 16, 0x1234, &[0x34, 0x00, 0x00, 0x12], gap);
gap.start = 2;
gap.length = 1;
test(4, 16, 0x1234, &[0x4f, 0x23, 0x00, 0xf1], gap);
}

565
src/embedded_flash/store/format.rs
View File

@@ -1,565 +0,0 @@
// Copyright 2019 Google LLC
//
// 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.
use super::super::{Index, Storage};
use super::{bitfield, StoreConfig, StoreEntry, StoreError};
use alloc::vec;
use alloc::vec::Vec;
/// Whether a user entry is a replace entry.
pub enum IsReplace {
/// This is a replace entry.
Replace,
/// This is an insert entry.
Insert,
}
/// Helpers to parse the store format.
///
/// See the store module-level documentation for information about the format.
pub struct Format {
pub word_size: usize,
pub page_size: usize,
pub num_pages: usize,
pub max_page_erases: usize,
pub num_tags: usize,
/// Whether an entry is present.
///
/// - 0 for entries (user entries or internal entries).
/// - 1 for free space until the end of the page.
present_bit: usize,
/// Whether an entry is deleted.
///
/// - 0 for deleted entries.
/// - 1 for alive entries.
deleted_bit: usize,
/// Whether an entry is internal.
///
/// - 0 for internal entries.
/// - 1 for user entries.
internal_bit: usize,
/// Whether a user entry is a replace entry.
///
/// - 0 for replace entries.
/// - 1 for insert entries.
replace_bit: usize,
/// Whether a user entry has sensitive data.
///
/// - 0 for sensitive data.
/// - 1 for non-sensitive data.
///
/// When a user entry with sensitive data is deleted, the data is overwritten with zeroes. This
/// feature is subject to the same guarantees as all other features of the store, in particular
/// deleting a sensitive entry is atomic. See the store module-level documentation for more
/// information.
sensitive_bit: usize,
/// The data length of a user entry.
length_range: bitfield::BitRange,
/// The tag of a user entry.
tag_range: bitfield::BitRange,
/// The page index of a replace entry.
replace_page_range: bitfield::BitRange,
/// The byte index of a replace entry.
replace_byte_range: bitfield::BitRange,
/// The index of the page to erase.
///
/// This is only present for internal entries.
old_page_range: bitfield::BitRange,
/// The current erase count of the page to erase.
///
/// This is only present for internal entries.
saved_erase_count_range: bitfield::BitRange,
/// Whether a page is initialized.
///
/// - 0 for initialized pages.
/// - 1 for uninitialized pages.
initialized_bit: usize,
/// The erase count of a page.
erase_count_range: bitfield::BitRange,
/// Whether a page is being compacted.
///
/// - 0 for pages being compacted.
/// - 1 otherwise.
compacting_bit: usize,
/// The page index to which a page is being compacted.
new_page_range: bitfield::BitRange,
}
impl Format {
/// Returns a helper to parse the store format for a given storage and config.
///
/// # Errors
///
/// Returns `None` if any of the following conditions does not hold:
/// - The word size must be a power of two.
/// - The page size must be a power of two.
/// - There should be at least 2 pages in the storage.
/// - It should be possible to write a word at least twice.
/// - It should be possible to erase a page at least once.
/// - There should be at least 1 tag.
pub fn new<S: Storage, C: StoreConfig>(storage: &S, config: &C) -> Option<Format> {
let word_size = storage.word_size();
let page_size = storage.page_size();
let num_pages = storage.num_pages();
let max_word_writes = storage.max_word_writes();
let max_page_erases = storage.max_page_erases();
let num_tags = config.num_tags();
if !(word_size.is_power_of_two()
&& page_size.is_power_of_two()
&& num_pages > 1
&& max_word_writes >= 2
&& max_page_erases > 0
&& num_tags > 0)
{
return None;
}
// Compute how many bits we need to store the fields.
let page_bits = num_bits(num_pages);
let byte_bits = num_bits(page_size);
let tag_bits = num_bits(num_tags);
let erase_bits = num_bits(max_page_erases + 1);
// Compute the bit position of the fields.
let present_bit = 0;
let deleted_bit = present_bit + 1;
let internal_bit = deleted_bit + 1;
let replace_bit = internal_bit + 1;
let sensitive_bit = replace_bit + 1;
let length_range = bitfield::BitRange {
start: sensitive_bit + 1,
length: byte_bits,
};
let tag_range = bitfield::BitRange {
start: length_range.end(),
length: tag_bits,
};
let replace_page_range = bitfield::BitRange {
start: tag_range.end(),
length: page_bits,
};
let replace_byte_range = bitfield::BitRange {
start: replace_page_range.end(),
length: byte_bits,
};
let old_page_range = bitfield::BitRange {
start: internal_bit + 1,
length: page_bits,
};
let saved_erase_count_range = bitfield::BitRange {
start: old_page_range.end(),
length: erase_bits,
};
let initialized_bit = 0;
let erase_count_range = bitfield::BitRange {
start: initialized_bit + 1,
length: erase_bits,
};
let compacting_bit = erase_count_range.end();
let new_page_range = bitfield::BitRange {
start: compacting_bit + 1,
length: page_bits,
};
let format = Format {
word_size,
page_size,
num_pages,
max_page_erases,
num_tags,
present_bit,
deleted_bit,
internal_bit,
replace_bit,
sensitive_bit,
length_range,
tag_range,
replace_page_range,
replace_byte_range,
old_page_range,
saved_erase_count_range,
initialized_bit,
erase_count_range,
compacting_bit,
new_page_range,
};
// Make sure all the following conditions hold:
// - The page header is one word.
// - The internal entry is one word.
// - The entry header fits in one word (which is equivalent to the entry header size being
// exactly one word for sensitive entries).
if format.page_header_size() != word_size
|| format.internal_entry_size() != word_size
|| format.header_size(true) != word_size
{
return None;
}
Some(format)
}
/// Ensures a user entry is valid.
pub fn validate_entry(&self, entry: StoreEntry) -> Result<(), StoreError> {
if entry.tag >= self.num_tags {
return Err(StoreError::InvalidTag);
}
if entry.data.len() >= self.page_size {
return Err(StoreError::StoreFull);
}
Ok(())
}
/// Returns the entry header length in bytes.
///
/// This is the smallest number of bytes necessary to store all fields of the entry info up to
/// and including `length`. For sensitive entries, the result is word-aligned.
pub fn header_size(&self, sensitive: bool) -> usize {
let mut size = self.bits_to_bytes(self.length_range.end());
if sensitive {
// We need to align to the next word boundary so that wiping the user data will not
// count as a write to the header.
size = self.align_word(size);
}
size
}
/// Returns the entry header length in bytes.
///
/// This is a convenience function for `header_size` above.
fn header_offset(&self, entry: &[u8]) -> usize {
self.header_size(self.is_sensitive(entry))
}
/// Returns the entry info length in bytes.
///
/// This is the number of bytes necessary to store all fields of the entry info. This also
/// includes the internal padding to protect the `committed` bit from the `deleted` bit and to
/// protect the entry info from the user data for sensitive entries.
fn info_size(&self, is_replace: IsReplace, sensitive: bool) -> usize {
let suffix_bits = 2; // committed + complete
let info_bits = match is_replace {
IsReplace::Replace => self.replace_byte_range.end() + suffix_bits,
IsReplace::Insert => self.tag_range.end() + suffix_bits,
};
let mut info_size = self.bits_to_bytes(info_bits);
// If the suffix bits would end up in the header, we need to add one byte for them.
let header_size = self.header_size(sensitive);
if info_size <= header_size {
info_size = header_size + 1;
}
// If the entry is sensitive, we need to align to the next word boundary.
if sensitive {
info_size = self.align_word(info_size);
}
info_size
}
/// Returns the length in bytes of an entry.
///
/// This depends on the length of the user data and whether the entry replaces an old entry or
/// is an insertion. This also includes the internal padding to protect the `committed` bit from
/// the `deleted` bit.
pub fn entry_size(&self, is_replace: IsReplace, sensitive: bool, length: usize) -> usize {
let mut entry_size = length + self.info_size(is_replace, sensitive);
let word_size = self.word_size;
entry_size = self.align_word(entry_size);
// The entry must be at least 2 words such that the `committed` and `deleted` bits are on
// different words.
if entry_size == word_size {
entry_size += word_size;
}
entry_size
}
/// Returns the length in bytes of an internal entry.
pub fn internal_entry_size(&self) -> usize {
let length = self.bits_to_bytes(self.saved_erase_count_range.end());
self.align_word(length)
}
pub fn is_present(&self, header: &[u8]) -> bool {
bitfield::is_zero(self.present_bit, header, bitfield::NO_GAP)
}
pub fn set_present(&self, header: &mut [u8]) {
bitfield::set_zero(self.present_bit, header, bitfield::NO_GAP)
}
pub fn is_deleted(&self, header: &[u8]) -> bool {
bitfield::is_zero(self.deleted_bit, header, bitfield::NO_GAP)
}
/// Returns whether an entry is present and not deleted.
pub fn is_alive(&self, header: &[u8]) -> bool {
self.is_present(header) && !self.is_deleted(header)
}
pub fn set_deleted(&self, header: &mut [u8]) {
bitfield::set_zero(self.deleted_bit, header, bitfield::NO_GAP)
}
pub fn is_internal(&self, header: &[u8]) -> bool {
bitfield::is_zero(self.internal_bit, header, bitfield::NO_GAP)
}
pub fn set_internal(&self, header: &mut [u8]) {
bitfield::set_zero(self.internal_bit, header, bitfield::NO_GAP)
}
pub fn is_replace(&self, header: &[u8]) -> IsReplace {
if bitfield::is_zero(self.replace_bit, header, bitfield::NO_GAP) {
IsReplace::Replace
} else {
IsReplace::Insert
}
}
fn set_replace(&self, header: &mut [u8]) {
bitfield::set_zero(self.replace_bit, header, bitfield::NO_GAP)
}
pub fn is_sensitive(&self, header: &[u8]) -> bool {
bitfield::is_zero(self.sensitive_bit, header, bitfield::NO_GAP)
}
pub fn set_sensitive(&self, header: &mut [u8]) {
bitfield::set_zero(self.sensitive_bit, header, bitfield::NO_GAP)
}
pub fn get_length(&self, header: &[u8]) -> usize {
bitfield::get_range(self.length_range, header, bitfield::NO_GAP)
}
fn set_length(&self, header: &mut [u8], length: usize) {
bitfield::set_range(self.length_range, header, bitfield::NO_GAP, length)
}
pub fn get_data<'a>(&self, entry: &'a [u8]) -> &'a [u8] {
&entry[self.header_offset(entry)..][..self.get_length(entry)]
}
/// Returns the span of user data in an entry.
///
/// The complement of this gap in the entry is exactly the entry info. The header is before the
/// gap and the footer is after the gap.
pub fn entry_gap(&self, entry: &[u8]) -> bitfield::ByteGap {
let start = self.header_offset(entry);
let mut length = self.get_length(entry);
if self.is_sensitive(entry) {
length = self.align_word(length);
}
bitfield::ByteGap { start, length }
}
pub fn get_tag(&self, entry: &[u8]) -> usize {
bitfield::get_range(self.tag_range, entry, self.entry_gap(entry))
}
fn set_tag(&self, entry: &mut [u8], tag: usize) {
bitfield::set_range(self.tag_range, entry, self.entry_gap(entry), tag)
}
pub fn get_replace_index(&self, entry: &[u8]) -> Index {
let gap = self.entry_gap(entry);
let page = bitfield::get_range(self.replace_page_range, entry, gap);
let byte = bitfield::get_range(self.replace_byte_range, entry, gap);
Index { page, byte }
}
fn set_replace_page(&self, entry: &mut [u8], page: usize) {
bitfield::set_range(self.replace_page_range, entry, self.entry_gap(entry), page)
}
fn set_replace_byte(&self, entry: &mut [u8], byte: usize) {
bitfield::set_range(self.replace_byte_range, entry, self.entry_gap(entry), byte)
}
/// Returns the bit position of the `committed` bit.
///
/// This cannot be precomputed like other fields since it depends on the length of the entry.
fn committed_bit(&self, entry: &[u8]) -> usize {
8 * entry.len() - 2
}
/// Returns the bit position of the `complete` bit.
///
/// This cannot be precomputed like other fields since it depends on the length of the entry.
fn complete_bit(&self, entry: &[u8]) -> usize {
8 * entry.len() - 1
}
pub fn is_committed(&self, entry: &[u8]) -> bool {
bitfield::is_zero(self.committed_bit(entry), entry, bitfield::NO_GAP)
}
pub fn set_committed(&self, entry: &mut [u8]) {
bitfield::set_zero(self.committed_bit(entry), entry, bitfield::NO_GAP)
}
pub fn is_complete(&self, entry: &[u8]) -> bool {
bitfield::is_zero(self.complete_bit(entry), entry, bitfield::NO_GAP)
}
fn set_complete(&self, entry: &mut [u8]) {
bitfield::set_zero(self.complete_bit(entry), entry, bitfield::NO_GAP)
}
pub fn get_old_page(&self, header: &[u8]) -> usize {
bitfield::get_range(self.old_page_range, header, bitfield::NO_GAP)
}
pub fn set_old_page(&self, header: &mut [u8], old_page: usize) {
bitfield::set_range(self.old_page_range, header, bitfield::NO_GAP, old_page)
}
pub fn get_saved_erase_count(&self, header: &[u8]) -> usize {
bitfield::get_range(self.saved_erase_count_range, header, bitfield::NO_GAP)
}
pub fn set_saved_erase_count(&self, header: &mut [u8], erase_count: usize) {
bitfield::set_range(
self.saved_erase_count_range,
header,
bitfield::NO_GAP,
erase_count,
)
}
/// Builds an entry for replace or insert operations.
pub fn build_entry(&self, replace: Option<Index>, user_entry: StoreEntry) -> Vec<u8> {
let StoreEntry {
tag,
data,
sensitive,
} = user_entry;
let is_replace = match replace {
None => IsReplace::Insert,
Some(_) => IsReplace::Replace,
};
let entry_len = self.entry_size(is_replace, sensitive, data.len());
let mut entry = Vec::with_capacity(entry_len);
// Build the header.
entry.resize(self.header_size(sensitive), 0xff);
self.set_present(&mut entry[..]);
if sensitive {
self.set_sensitive(&mut entry[..]);
}
self.set_length(&mut entry[..], data.len());
// Add the data.
entry.extend_from_slice(data);
// Build the footer.
entry.resize(entry_len, 0xff);
self.set_tag(&mut entry[..], tag);
self.set_complete(&mut entry[..]);
match replace {
None => self.set_committed(&mut entry[..]),
Some(Index { page, byte }) => {
self.set_replace(&mut entry[..]);
self.set_replace_page(&mut entry[..], page);
self.set_replace_byte(&mut entry[..], byte);
}
}
entry
}
/// Builds an entry for replace or insert operations.
pub fn build_erase_entry(&self, old_page: usize, saved_erase_count: usize) -> Vec<u8> {
let mut entry = vec![0xff; self.internal_entry_size()];
self.set_present(&mut entry[..]);
self.set_internal(&mut entry[..]);
self.set_old_page(&mut entry[..], old_page);
self.set_saved_erase_count(&mut entry[..], saved_erase_count);
entry
}
/// Returns the length in bytes of a page header entry.
///
/// This includes the word padding.
pub fn page_header_size(&self) -> usize {
self.align_word(self.bits_to_bytes(self.erase_count_range.end()))
}
pub fn is_initialized(&self, header: &[u8]) -> bool {
bitfield::is_zero(self.initialized_bit, header, bitfield::NO_GAP)
}
pub fn set_initialized(&self, header: &mut [u8]) {
bitfield::set_zero(self.initialized_bit, header, bitfield::NO_GAP)
}
pub fn get_erase_count(&self, header: &[u8]) -> usize {
bitfield::get_range(self.erase_count_range, header, bitfield::NO_GAP)
}
pub fn set_erase_count(&self, header: &mut [u8], count: usize) {
bitfield::set_range(self.erase_count_range, header, bitfield::NO_GAP, count)
}
pub fn is_compacting(&self, header: &[u8]) -> bool {
bitfield::is_zero(self.compacting_bit, header, bitfield::NO_GAP)
}
pub fn set_compacting(&self, header: &mut [u8]) {
bitfield::set_zero(self.compacting_bit, header, bitfield::NO_GAP)
}
pub fn get_new_page(&self, header: &[u8]) -> usize {
bitfield::get_range(self.new_page_range, header, bitfield::NO_GAP)
}
pub fn set_new_page(&self, header: &mut [u8], new_page: usize) {
bitfield::set_range(self.new_page_range, header, bitfield::NO_GAP, new_page)
}
/// Returns the smallest word boundary greater or equal to a value.
fn align_word(&self, value: usize) -> usize {
let word_size = self.word_size;
(value + word_size - 1) / word_size * word_size
}
/// Returns the minimum number of bytes to represent a given number of bits.
fn bits_to_bytes(&self, bits: usize) -> usize {
(bits + 7) / 8
}
}
/// Returns the number of bits necessary to write numbers smaller than `x`.
fn num_bits(x: usize) -> usize {
x.next_power_of_two().trailing_zeros() as usize
}
#[test]
fn num_bits_ok() {
assert_eq!(num_bits(0), 0);
assert_eq!(num_bits(1), 0);
assert_eq!(num_bits(2), 1);
assert_eq!(num_bits(3), 2);
assert_eq!(num_bits(4), 2);
assert_eq!(num_bits(5), 3);
assert_eq!(num_bits(8), 3);
assert_eq!(num_bits(9), 4);
assert_eq!(num_bits(16), 4);
}

1182
src/embedded_flash/store/mod.rs
View File

File diff suppressed because it is too large Load Diff

36
src/embedded_flash/syscall.rs
View File

@@ -1,4 +1,4 @@
// Copyright 2019 Google LLC
// Copyright 2019-2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
@@ -12,9 +12,9 @@
// See the License for the specific language governing permissions and
// limitations under the License.
use super::{Index, Storage, StorageError, StorageResult};
use alloc::vec::Vec;
use libtock_core::syscalls;
use persistent_store::{Storage, StorageError, StorageIndex, StorageResult};
const DRIVER_NUMBER: usize = 0x50003;
@@ -42,15 +42,13 @@ mod memop_nr {
fn get_info(nr: usize, arg: usize) -> StorageResult<usize> {
let code = syscalls::command(DRIVER_NUMBER, command_nr::GET_INFO, nr, arg);
code.map_err(|e| StorageError::KernelError {
code: e.return_code,
})
code.map_err(|_| StorageError::CustomError)
}
fn memop(nr: u32, arg: usize) -> StorageResult<usize> {
let code = unsafe { syscalls::raw::memop(nr, arg) };
if code < 0 {
Err(StorageError::KernelError { code })
Err(StorageError::CustomError)
} else {
Ok(code as usize)
}
@@ -70,7 +68,7 @@ impl SyscallStorage {
///
/// # Errors
///
/// Returns `BadFlash` if any of the following conditions do not hold:
/// Returns `CustomError` if any of the following conditions do not hold:
/// - The word size is a power of two.
/// - The page size is a power of two.
/// - The page size is a multiple of the word size.
@@ -90,13 +88,13 @@ impl SyscallStorage {
|| !syscall.page_size.is_power_of_two()
|| !syscall.is_word_aligned(syscall.page_size)
{
return Err(StorageError::BadFlash);
return Err(StorageError::CustomError);
}
for i in 0..memop(memop_nr::STORAGE_CNT, 0)? {
let storage_ptr = memop(memop_nr::STORAGE_PTR, i)?;
let max_storage_len = memop(memop_nr::STORAGE_LEN, i)?;
if !syscall.is_page_aligned(storage_ptr) || !syscall.is_page_aligned(max_storage_len) {
return Err(StorageError::BadFlash);
return Err(StorageError::CustomError);
}
let storage_len = core::cmp::min(num_pages * syscall.page_size, max_storage_len);
num_pages -= storage_len / syscall.page_size;
@@ -141,12 +139,12 @@ impl Storage for SyscallStorage {
self.max_page_erases
}
fn read_slice(&self, index: Index, length: usize) -> StorageResult<&[u8]> {
fn read_slice(&self, index: StorageIndex, length: usize) -> StorageResult<&[u8]> {
let start = index.range(length, self)?.start;
find_slice(&self.storage_locations, start, length)
}
fn write_slice(&mut self, index: Index, value: &[u8]) -> StorageResult<()> {
fn write_slice(&mut self, index: StorageIndex, value: &[u8]) -> StorageResult<()> {
if !self.is_word_aligned(index.byte) || !self.is_word_aligned(value.len()) {
return Err(StorageError::NotAligned);
}
@@ -163,28 +161,24 @@ impl Storage for SyscallStorage {
)
};
if code < 0 {
return Err(StorageError::KernelError { code });
return Err(StorageError::CustomError);
}
let code = syscalls::command(DRIVER_NUMBER, command_nr::WRITE_SLICE, ptr, value.len());
if let Err(e) = code {
return Err(StorageError::KernelError {
code: e.return_code,
});
if code.is_err() {
return Err(StorageError::CustomError);
}
Ok(())
}
fn erase_page(&mut self, page: usize) -> StorageResult<()> {
let index = Index { page, byte: 0 };
let index = StorageIndex { page, byte: 0 };
let length = self.page_size();
let ptr = self.read_slice(index, length)?.as_ptr() as usize;
let code = syscalls::command(DRIVER_NUMBER, command_nr::ERASE_PAGE, ptr, length);
if let Err(e) = code {
return Err(StorageError::KernelError {
code: e.return_code,
});
if code.is_err() {
return Err(StorageError::CustomError);
}
Ok(())
}