Add Storage and UpgradeStorage to Env

src/env/tock/mod.rs

@@ -0,0 +1,287 @@
+use self::storage::{SyscallStorage, SyscallUpgradeStorage};
+use crate::ctap::hid::{ChannelID, CtapHid, KeepaliveStatus, ProcessedPacket};
+use crate::ctap::status_code::Ctap2StatusCode;
+use crate::env::{Env, UserPresence};
+use core::cell::Cell;
+#[cfg(feature = "debug_ctap")]
+use core::fmt::Write;
+use core::sync::atomic::{AtomicBool, Ordering};
+use crypto::rng256::TockRng256;
+use libtock_core::result::{CommandError, EALREADY};
+use libtock_drivers::buttons::{self, ButtonState};
+#[cfg(feature = "debug_ctap")]
+use libtock_drivers::console::Console;
+use libtock_drivers::result::{FlexUnwrap, TockError};
+use libtock_drivers::timer::Duration;
+use libtock_drivers::{led, timer, usb_ctap_hid};
+use persistent_store::StorageResult;
+
+mod storage;
+
+pub struct TockEnv {
+    rng: TockRng256,
+    storage: bool,
+    upgrade_storage: bool,
+}
+
+impl TockEnv {
+    /// Returns the unique instance of the Tock environment.
+    ///
+    /// This function returns `Some` the first time it is called. Afterwards, it repeatedly returns
+    /// `None`.
+    pub fn new() -> Option<Self> {
+        // Make sure the environment was not already taken.
+        static TAKEN: AtomicBool = AtomicBool::new(false);
+        if TAKEN.fetch_or(true, Ordering::SeqCst) {
+            return None;
+        }
+        Some(TockEnv {
+            rng: TockRng256 {},
+            storage: false,
+            upgrade_storage: false,
+        })
+    }
+}
+
+/// Creates a new storage instance.
+///
+/// # Safety
+///
+/// It is probably technically memory-safe to hame multiple storage instances at the same time, but
+/// for extra precaution we mark the function as unsafe. To ensure correct usage, this function
+/// should only be called if the previous storage instance was dropped.
+// This function is exposed for example binaries testing the hardware. This could probably be
+// cleaned up by having the persistent store return its storage.
+pub unsafe fn steal_storage() -> StorageResult<SyscallStorage> {
+    SyscallStorage::new()
+}
+
+impl UserPresence for TockEnv {
+    fn check(&self, cid: ChannelID) -> Result<(), Ctap2StatusCode> {
+        check_user_presence(cid)
+    }
+}
+
+impl Env for TockEnv {
+    type Rng = TockRng256;
+    type UserPresence = Self;
+    type Storage = SyscallStorage;
+    type UpgradeStorage = SyscallUpgradeStorage;
+
+    fn rng(&mut self) -> &mut Self::Rng {
+        &mut self.rng
+    }
+
+    fn user_presence(&mut self) -> &mut Self::UserPresence {
+        self
+    }
+
+    fn storage(&mut self) -> StorageResult<Self::Storage> {
+        assert!(!self.storage);
+        self.storage = true;
+        unsafe { steal_storage() }
+    }
+
+    fn upgrade_storage(&mut self) -> StorageResult<Self::UpgradeStorage> {
+        assert!(!self.upgrade_storage);
+        self.upgrade_storage = true;
+        SyscallUpgradeStorage::new()
+    }
+}
+
+// Returns whether the keepalive was sent, or false if cancelled.
+fn send_keepalive_up_needed(
+    cid: ChannelID,
+    timeout: Duration<isize>,
+) -> Result<(), Ctap2StatusCode> {
+    let keepalive_msg = CtapHid::keepalive(cid, KeepaliveStatus::UpNeeded);
+    for mut pkt in keepalive_msg {
+        let status = usb_ctap_hid::send_or_recv_with_timeout(&mut pkt, timeout);
+        match status {
+            None => {
+                #[cfg(feature = "debug_ctap")]
+                writeln!(Console::new(), "Sending a KEEPALIVE packet timed out").unwrap();
+                // TODO: abort user presence test?
+            }
+            Some(usb_ctap_hid::SendOrRecvStatus::Error) => panic!("Error sending KEEPALIVE packet"),
+            Some(usb_ctap_hid::SendOrRecvStatus::Sent) => {
+                #[cfg(feature = "debug_ctap")]
+                writeln!(Console::new(), "Sent KEEPALIVE packet").unwrap();
+            }
+            Some(usb_ctap_hid::SendOrRecvStatus::Received) => {
+                // We only parse one packet, because we only care about CANCEL.
+                let (received_cid, processed_packet) = CtapHid::process_single_packet(&pkt);
+                if received_cid != &cid {
+                    #[cfg(feature = "debug_ctap")]
+                    writeln!(
+                        Console::new(),
+                        "Received a packet on channel ID {:?} while sending a KEEPALIVE packet",
+                        received_cid,
+                    )
+                    .unwrap();
+                    return Ok(());
+                }
+                match processed_packet {
+                    ProcessedPacket::InitPacket { cmd, .. } => {
+                        if cmd == CtapHid::COMMAND_CANCEL {
+                            // We ignore the payload, we can't answer with an error code anyway.
+                            #[cfg(feature = "debug_ctap")]
+                            writeln!(Console::new(), "User presence check cancelled").unwrap();
+                            return Err(Ctap2StatusCode::CTAP2_ERR_KEEPALIVE_CANCEL);
+                        } else {
+                            #[cfg(feature = "debug_ctap")]
+                            writeln!(
+                                Console::new(),
+                                "Discarded packet with command {} received while sending a KEEPALIVE packet",
+                                cmd,
+                            )
+                            .unwrap();
+                        }
+                    }
+                    ProcessedPacket::ContinuationPacket { .. } => {
+                        #[cfg(feature = "debug_ctap")]
+                        writeln!(
+                            Console::new(),
+                            "Discarded continuation packet received while sending a KEEPALIVE packet",
+                        )
+                        .unwrap();
+                    }
+                }
+            }
+        }
+    }
+    Ok(())
+}
+
+pub fn blink_leds(pattern_seed: usize) {
+    for l in 0..led::count().flex_unwrap() {
+        if (pattern_seed ^ l).count_ones() & 1 != 0 {
+            led::get(l).flex_unwrap().on().flex_unwrap();
+        } else {
+            led::get(l).flex_unwrap().off().flex_unwrap();
+        }
+    }
+}
+
+pub fn wink_leds(pattern_seed: usize) {
+    // This generates a "snake" pattern circling through the LEDs.
+    // Fox example with 4 LEDs the sequence of lit LEDs will be the following.
+    // 0 1 2 3
+    // * *
+    // * * *
+    //   * *
+    //   * * *
+    //     * *
+    // *   * *
+    // *     *
+    // * *   *
+    // * *
+    let count = led::count().flex_unwrap();
+    let a = (pattern_seed / 2) % count;
+    let b = ((pattern_seed + 1) / 2) % count;
+    let c = ((pattern_seed + 3) / 2) % count;
+
+    for l in 0..count {
+        // On nRF52840-DK, logically swap LEDs 3 and 4 so that the order of LEDs form a circle.
+        let k = match l {
+            2 => 3,
+            3 => 2,
+            _ => l,
+        };
+        if k == a || k == b || k == c {
+            led::get(l).flex_unwrap().on().flex_unwrap();
+        } else {
+            led::get(l).flex_unwrap().off().flex_unwrap();
+        }
+    }
+}
+
+pub fn switch_off_leds() {
+    for l in 0..led::count().flex_unwrap() {
+        led::get(l).flex_unwrap().off().flex_unwrap();
+    }
+}
+
+const KEEPALIVE_DELAY_MS: isize = 100;
+pub const KEEPALIVE_DELAY: Duration<isize> = Duration::from_ms(KEEPALIVE_DELAY_MS);
+
+fn check_user_presence(cid: ChannelID) -> Result<(), Ctap2StatusCode> {
+    // The timeout is N times the keepalive delay.
+    const TIMEOUT_ITERATIONS: usize =
+        crate::ctap::TOUCH_TIMEOUT_MS as usize / KEEPALIVE_DELAY_MS as usize;
+
+    // First, send a keep-alive packet to notify that the keep-alive status has changed.
+    send_keepalive_up_needed(cid, KEEPALIVE_DELAY)?;
+
+    // Listen to the button presses.
+    let button_touched = Cell::new(false);
+    let mut buttons_callback = buttons::with_callback(|_button_num, state| {
+        match state {
+            ButtonState::Pressed => button_touched.set(true),
+            ButtonState::Released => (),
+        };
+    });
+    let mut buttons = buttons_callback.init().flex_unwrap();
+    // At the moment, all buttons are accepted. You can customize your setup here.
+    for mut button in &mut buttons {
+        button.enable().flex_unwrap();
+    }
+
+    let mut keepalive_response = Ok(());
+    for i in 0..TIMEOUT_ITERATIONS {
+        blink_leds(i);
+
+        // Setup a keep-alive callback.
+        let keepalive_expired = Cell::new(false);
+        let mut keepalive_callback = timer::with_callback(|_, _| {
+            keepalive_expired.set(true);
+        });
+        let mut keepalive = keepalive_callback.init().flex_unwrap();
+        let keepalive_alarm = keepalive.set_alarm(KEEPALIVE_DELAY).flex_unwrap();
+
+        // Wait for a button touch or an alarm.
+        libtock_drivers::util::yieldk_for(|| button_touched.get() || keepalive_expired.get());
+
+        // Cleanup alarm callback.
+        match keepalive.stop_alarm(keepalive_alarm) {
+            Ok(()) => (),
+            Err(TockError::Command(CommandError {
+                return_code: EALREADY,
+                ..
+            })) => assert!(keepalive_expired.get()),
+            Err(_e) => {
+                #[cfg(feature = "debug_ctap")]
+                panic!("Unexpected error when stopping alarm: {:?}", _e);
+                #[cfg(not(feature = "debug_ctap"))]
+                panic!("Unexpected error when stopping alarm: <error is only visible with the debug_ctap feature>");
+            }
+        }
+
+        // TODO: this may take arbitrary time. The keepalive_delay should be adjusted accordingly,
+        // so that LEDs blink with a consistent pattern.
+        if keepalive_expired.get() {
+            // Do not return immediately, because we must clean up still.
+            keepalive_response = send_keepalive_up_needed(cid, KEEPALIVE_DELAY);
+        }
+
+        if button_touched.get() || keepalive_response.is_err() {
+            break;
+        }
+    }
+
+    switch_off_leds();
+
+    // Cleanup button callbacks.
+    for mut button in &mut buttons {
+        button.disable().flex_unwrap();
+    }
+
+    // Returns whether the user was present.
+    if keepalive_response.is_err() {
+        keepalive_response
+    } else if button_touched.get() {
+        Ok(())
+    } else {
+        Err(Ctap2StatusCode::CTAP2_ERR_USER_ACTION_TIMEOUT)
+    }
+}

src/env/tock/storage.rs

@@ -0,0 +1,349 @@
+// Copyright 2019-2021 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 crate::api::upgrade_storage::helper::{find_slice, is_aligned, ModRange};
+use crate::api::upgrade_storage::UpgradeStorage;
+use alloc::vec::Vec;
+use core::cell::Cell;
+use libtock_core::{callback, syscalls};
+use persistent_store::{Storage, StorageError, StorageIndex, StorageResult};
+
+const DRIVER_NUMBER: usize = 0x50003;
+
+mod subscribe_nr {
+    pub const DONE: usize = 0;
+}
+
+mod command_nr {
+    pub const GET_INFO: usize = 1;
+    pub mod get_info_nr {
+        pub const WORD_SIZE: usize = 0;
+        pub const PAGE_SIZE: usize = 1;
+        pub const MAX_WORD_WRITES: usize = 2;
+        pub const MAX_PAGE_ERASES: usize = 3;
+    }
+    pub const WRITE_SLICE: usize = 2;
+    pub const ERASE_PAGE: usize = 3;
+}
+
+mod allow_nr {
+    pub const WRITE_SLICE: usize = 0;
+}
+
+mod memop_nr {
+    pub const STORAGE_CNT: u32 = 12;
+    pub const STORAGE_PTR: u32 = 13;
+    pub const STORAGE_LEN: u32 = 14;
+    pub const STORAGE_TYPE: u32 = 15;
+}
+
+mod storage_type {
+    pub const STORE: usize = 1;
+    pub const PARTITION: usize = 2;
+    pub const METADATA: usize = 3;
+}
+
+fn get_info(nr: usize, arg: usize) -> StorageResult<usize> {
+    let code = syscalls::command(DRIVER_NUMBER, command_nr::GET_INFO, nr, arg);
+    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::CustomError)
+    } else {
+        Ok(code as usize)
+    }
+}
+
+fn block_command(driver: usize, cmd: usize, arg1: usize, arg2: usize) -> StorageResult<()> {
+    let done = Cell::new(None);
+    let mut alarm = |status| done.set(Some(status));
+    let subscription = syscalls::subscribe::<callback::Identity1Consumer, _>(
+        DRIVER_NUMBER,
+        subscribe_nr::DONE,
+        &mut alarm,
+    );
+    if subscription.is_err() {
+        return Err(StorageError::CustomError);
+    }
+
+    let code = syscalls::command(driver, cmd, arg1, arg2);
+    if code.is_err() {
+        return Err(StorageError::CustomError);
+    }
+
+    libtock_drivers::util::yieldk_for(|| done.get().is_some());
+    if done.get().unwrap() == 0 {
+        Ok(())
+    } else {
+        Err(StorageError::CustomError)
+    }
+}
+
+fn write_slice(ptr: usize, value: &[u8]) -> StorageResult<()> {
+    let code = unsafe {
+        syscalls::raw::allow(
+            DRIVER_NUMBER,
+            allow_nr::WRITE_SLICE,
+            // We rely on the driver not writing to the slice. This should use read-only allow
+            // when available. See https://github.com/tock/tock/issues/1274.
+            value.as_ptr() as *mut u8,
+            value.len(),
+        )
+    };
+    if code < 0 {
+        return Err(StorageError::CustomError);
+    }
+
+    block_command(DRIVER_NUMBER, command_nr::WRITE_SLICE, ptr, value.len())
+}
+
+fn erase_page(ptr: usize, page_length: usize) -> StorageResult<()> {
+    block_command(DRIVER_NUMBER, command_nr::ERASE_PAGE, ptr, page_length)
+}
+
+pub struct SyscallStorage {
+    word_size: usize,
+    page_size: usize,
+    num_pages: usize,
+    max_word_writes: usize,
+    max_page_erases: usize,
+    storage_locations: Vec<&'static [u8]>,
+}
+
+impl SyscallStorage {
+    /// Provides access to the embedded flash if available.
+    ///
+    /// # Errors
+    ///
+    /// 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.
+    /// - The storage is page-aligned.
+    pub fn new() -> StorageResult<SyscallStorage> {
+        let mut syscall = SyscallStorage {
+            word_size: get_info(command_nr::get_info_nr::WORD_SIZE, 0)?,
+            page_size: get_info(command_nr::get_info_nr::PAGE_SIZE, 0)?,
+            num_pages: 0,
+            max_word_writes: get_info(command_nr::get_info_nr::MAX_WORD_WRITES, 0)?,
+            max_page_erases: get_info(command_nr::get_info_nr::MAX_PAGE_ERASES, 0)?,
+            storage_locations: Vec::new(),
+        };
+        if !syscall.word_size.is_power_of_two()
+            || !syscall.page_size.is_power_of_two()
+            || !syscall.is_word_aligned(syscall.page_size)
+        {
+            return Err(StorageError::CustomError);
+        }
+        for i in 0..memop(memop_nr::STORAGE_CNT, 0)? {
+            if memop(memop_nr::STORAGE_TYPE, i)? != storage_type::STORE {
+                continue;
+            }
+            let storage_ptr = memop(memop_nr::STORAGE_PTR, i)?;
+            let storage_len = memop(memop_nr::STORAGE_LEN, i)?;
+            if !syscall.is_page_aligned(storage_ptr) || !syscall.is_page_aligned(storage_len) {
+                return Err(StorageError::CustomError);
+            }
+            syscall.num_pages += storage_len / syscall.page_size;
+            syscall
+                .storage_locations
+                .push(unsafe { core::slice::from_raw_parts(storage_ptr as *mut u8, storage_len) });
+        }
+        Ok(syscall)
+    }
+
+    fn is_word_aligned(&self, x: usize) -> bool {
+        is_aligned(self.word_size, x)
+    }
+
+    fn is_page_aligned(&self, x: usize) -> bool {
+        is_aligned(self.page_size, x)
+    }
+}
+
+impl Storage for SyscallStorage {
+    fn word_size(&self) -> usize {
+        self.word_size
+    }
+
+    fn page_size(&self) -> usize {
+        self.page_size
+    }
+
+    fn num_pages(&self) -> usize {
+        self.num_pages
+    }
+
+    fn max_word_writes(&self) -> usize {
+        self.max_word_writes
+    }
+
+    fn max_page_erases(&self) -> usize {
+        self.max_page_erases
+    }
+
+    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: StorageIndex, value: &[u8]) -> StorageResult<()> {
+        if !self.is_word_aligned(index.byte) || !self.is_word_aligned(value.len()) {
+            return Err(StorageError::NotAligned);
+        }
+        let ptr = self.read_slice(index, value.len())?.as_ptr() as usize;
+        write_slice(ptr, value)
+    }
+
+    fn erase_page(&mut self, page: usize) -> StorageResult<()> {
+        let index = StorageIndex { page, byte: 0 };
+        let length = self.page_size();
+        let ptr = self.read_slice(index, length)?.as_ptr() as usize;
+        erase_page(ptr, length)
+    }
+}
+
+pub struct SyscallUpgradeStorage {
+    page_size: usize,
+    partition: ModRange,
+    metadata: ModRange,
+}
+
+impl SyscallUpgradeStorage {
+    /// Provides access to the other upgrade partition and metadata if available.
+    ///
+    /// The implementation assumes that storage locations returned by the kernel through
+    /// `memop_nr::STORAGE_*` calls are in address space order.
+    ///
+    /// # Errors
+    ///
+    /// Returns `CustomError` if any of the following conditions do not hold:
+    /// - The page size is a power of two.
+    /// - The storage slices are page-aligned.
+    /// - There are not partition or metadata slices.
+    /// Returns a `NotAligned` error if partitions or metadata ranges are
+    /// - not exclusive or,
+    /// - not consecutive.
+    pub fn new() -> StorageResult<SyscallUpgradeStorage> {
+        let mut locations = SyscallUpgradeStorage {
+            page_size: get_info(command_nr::get_info_nr::PAGE_SIZE, 0)?,
+            partition: ModRange::new_empty(),
+            metadata: ModRange::new_empty(),
+        };
+        if !locations.page_size.is_power_of_two() {
+            return Err(StorageError::CustomError);
+        }
+        for i in 0..memop(memop_nr::STORAGE_CNT, 0)? {
+            let storage_type = memop(memop_nr::STORAGE_TYPE, i)?;
+            match storage_type {
+                storage_type::PARTITION | storage_type::METADATA => (),
+                _ => continue,
+            };
+            let storage_ptr = memop(memop_nr::STORAGE_PTR, i)?;
+            let storage_len = memop(memop_nr::STORAGE_LEN, i)?;
+            if !locations.is_page_aligned(storage_ptr) || !locations.is_page_aligned(storage_len) {
+                return Err(StorageError::CustomError);
+            }
+            let range = ModRange::new(storage_ptr, storage_len);
+            match storage_type {
+                storage_type::PARTITION => {
+                    locations.partition = locations
+                        .partition
+                        .append(range)
+                        .ok_or(StorageError::NotAligned)?
+                }
+                storage_type::METADATA => {
+                    locations.metadata = locations
+                        .metadata
+                        .append(range)
+                        .ok_or(StorageError::NotAligned)?
+                }
+                _ => (),
+            };
+        }
+        if locations.partition.is_empty() || locations.metadata.is_empty() {
+            Err(StorageError::CustomError)
+        } else {
+            Ok(locations)
+        }
+    }
+
+    fn is_page_aligned(&self, x: usize) -> bool {
+        is_aligned(self.page_size, x)
+    }
+}
+
+impl UpgradeStorage for SyscallUpgradeStorage {
+    fn read_partition(&self, offset: usize, length: usize) -> StorageResult<&[u8]> {
+        if length == 0 {
+            return Err(StorageError::OutOfBounds);
+        }
+        let address = self.partition.start() + offset;
+        if self
+            .partition
+            .contains_range(&ModRange::new(address, length))
+        {
+            Ok(unsafe { core::slice::from_raw_parts(address as *const u8, length) })
+        } else {
+            Err(StorageError::OutOfBounds)
+        }
+    }
+
+    fn write_partition(&mut self, offset: usize, data: &[u8]) -> StorageResult<()> {
+        if data.is_empty() {
+            return Err(StorageError::OutOfBounds);
+        }
+        let address = self.partition.start() + offset;
+        let write_range = ModRange::new(address, data.len());
+        if self.partition.contains_range(&write_range) {
+            // Erases all pages that have their first byte in the write range.
+            // Since we expect calls in order, we don't want to erase half-written pages.
+            for address in write_range.aligned_iter(self.page_size) {
+                erase_page(address, self.page_size)?;
+            }
+            write_slice(address, data)
+        } else {
+            Err(StorageError::OutOfBounds)
+        }
+    }
+
+    fn partition_address(&self) -> usize {
+        self.partition.start()
+    }
+
+    fn partition_length(&self) -> usize {
+        self.partition.length()
+    }
+
+    fn read_metadata(&self) -> StorageResult<&[u8]> {
+        Ok(unsafe {
+            core::slice::from_raw_parts(self.metadata.start() as *const u8, self.metadata.length())
+        })
+    }
+
+    fn write_metadata(&mut self, data: &[u8]) -> StorageResult<()> {
+        // If less data is passed in than is reserved, assume the rest is 0xFF.
+        if data.len() <= self.metadata.length() {
+            for address in self.metadata.aligned_iter(self.page_size) {
+                erase_page(address, self.page_size)?;
+            }
+            write_slice(self.metadata.start(), data)
+        } else {
+            Err(StorageError::OutOfBounds)
+        }
+    }
+}