Merge branch 'develop' into env_store

.gitignore

@@ -1,3 +1,4 @@
+fuzz/corpus
 target/
 Cargo.lock
 

bootloader/Cargo.toml

@@ -15,6 +15,7 @@ cortex-m-rt = "*"
 cortex-m-rt-macros = "*"
 panic-abort = "0.3.2"
 rtt-target = { version = "*", features = ["cortex-m"] }
+tock-registers = { version = "0.6.0", features = ["no_std_unit_tests"] }
 
 [profile.dev]
 panic = "abort"

bootloader/src/bitfields.rs

@@ -0,0 +1,118 @@
+// Copyright 2020-2022 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 tock_registers::register_bitfields;
+
+register_bitfields! [u32,
+    // Generic or shared bitfields
+    pub Task [
+        ENABLE OFFSET(0) NUMBITS(1)
+    ],
+
+    pub Byte [
+        VALUE OFFSET(0) NUMBITS(8)
+    ],
+
+    pub Busy [
+        /// Asserted when AES_BUSY or DES_BUSY or HASH_BUSY are asserted or when the DIN FIFO is not empty
+        BUSY OFFSET(0) NUMBITS(1) [
+            Ready = 0,
+            Busy = 1
+        ]
+    ],
+
+    // CC_CTL register bitfields
+    pub CryptoMode [
+        /// Determines the active cryptographic engine
+        MODE OFFSET(0) NUMBITS(5) [
+            Bypass = 0,
+            Aes = 1,
+            AesToHash = 2,
+            AesAndHash = 3,
+            Des = 4,
+            DesToHash = 5,
+            DesAndHash = 6,
+            Hash = 7,
+            AesMacAndBypass = 9,
+            AesToHashAndDout = 10
+        ]
+    ],
+
+    // HOST_RGF register bitfields
+    pub Interrupts [
+        /// This interrupt is asserted when all data was delivered to DIN buffer from SRAM
+        SRAM_TO_DIN OFFSET(4) NUMBITS(1),
+        /// This interrupt is asserted when all data was delivered to SRAM buffer from DOUT
+        DOUT_TO_SRAM OFFSET(5) NUMBITS(1),
+        /// This interrupt is asserted when all data was delivered to DIN buffer from memory
+        MEM_TO_DIN OFFSET(6) NUMBITS(1),
+        /// This interrupt is asserted when all data was delivered to memory buffer from DOUT
+        DOUT_TO_MEM OFFSET(7) NUMBITS(1),
+        AXI_ERROR OFFSET(8) NUMBITS(1),
+        /// The PKA end of operation interrupt status
+        PKA_EXP OFFSET(9) NUMBITS(1),
+        /// The RNG interrupt status
+        RNG OFFSET(10) NUMBITS(1),
+        /// The GPR interrupt status
+        SYM_DMA_COMPLETED OFFSET(11) NUMBITS(1)
+    ],
+
+    pub RgfEndianness [
+        /// DOUT write endianness
+        DOUT_WR_BG OFFSET(3) NUMBITS(1) [
+            LittleEndian = 0,
+            BigEndian = 1
+        ],
+        /// DIN write endianness
+        DIN_RD_BG OFFSET(7) NUMBITS(1) [
+            LittleEndian = 0,
+            BigEndian = 1
+        ],
+        /// DOUT write word endianness
+        DOUT_WR_WBG OFFSET(11) NUMBITS(1) [
+            LittleEndian = 0,
+            BigEndian = 1
+        ],
+        /// DIN write word endianness
+        DIN_RD_WBG OFFSET(15) NUMBITS(1) [
+            LittleEndian = 0,
+            BigEndian = 1
+        ]
+    ],
+
+    // DIN and DOUT register bitfields
+    pub LliWord1 [
+        /// Total number of bytes to read using DMA in this entry
+        BYTES_NUM OFFSET(0) NUMBITS(30),
+        /// Indicates the first LLI entry
+        FIRST OFFSET(30) NUMBITS(1),
+        /// Indicates the last LLI entry
+        LAST OFFSET(31) NUMBITS(1)
+    ],
+
+    pub HashControl [
+        // bit 2 is reserved but to simplify the logic we include it in the bitfield.
+        MODE OFFSET(0) NUMBITS(4) [
+            MD5 = 0,
+            SHA1 = 1,
+            SHA256 = 2,
+            SHA224 = 10
+        ]
+    ],
+
+    pub PaddingConfig [
+        /// Enable Padding generation. must be reset upon completion of padding.
+        DO_PAD OFFSET(2) NUMBITS(1)
+    ]
+];

bootloader/src/crypto_cell.rs

@@ -0,0 +1,283 @@
+// Copyright 2019-2022 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.
+
+//! CryptoCell 310
+//!
+//! Author
+//! -------------------
+//!
+//! * Author: Jean-Michel Picod <jmichel@google.com>
+//! * Date: October 1 2019
+
+use super::bitfields;
+use super::registers::{CryptoCellRegisters, NordicCC310Registers};
+use super::static_ref::StaticRef;
+use core::cell::Cell;
+#[cfg(debug_assertions)]
+use rtt_target::rprintln;
+
+const SHA256_INIT_VALUE: [u32; 8] = [
+    0x6A09E667, 0xBB67AE85, 0x3C6EF372, 0xA54FF53A, 0x510E527F, 0x9B05688C, 0x1F83D9AB, 0x5BE0CD19,
+];
+
+#[derive(Copy, Clone)]
+enum DigestAlgorithm {
+    Sha256 = 2,
+}
+
+#[derive(Copy, Clone)]
+enum OperationMode {
+    Idle,
+    Hash,
+}
+
+pub struct CryptoCell310 {
+    registers: StaticRef<CryptoCellRegisters>,
+    power: StaticRef<NordicCC310Registers>,
+    current_op: Cell<OperationMode>,
+
+    hash_ctx: Cell<[u32; 8]>,
+    hash_total_size: Cell<u64>,
+}
+
+const CC310_BASE: StaticRef<CryptoCellRegisters> =
+    unsafe { StaticRef::new(0x5002B000 as *const CryptoCellRegisters) };
+const CC310_POWER: StaticRef<NordicCC310Registers> =
+    unsafe { StaticRef::new(0x5002A500 as *const NordicCC310Registers) };
+
+// Identification "signature" for CryptoCell. According to the documentation, the value
+// held by this register is a fixed value, used by Host driver to verify CryptoCell presence
+// at this address.
+// This value was read from a CryptoCell-310 on a nRF52840-dongle kit.
+const CC310_SIGNATURE: u32 = 0x20E00000;
+
+impl CryptoCell310 {
+    /// Creates a new instance of cryptocell state.
+    pub const fn new() -> Self {
+        CryptoCell310 {
+            registers: CC310_BASE,
+            power: CC310_POWER,
+            current_op: Cell::new(OperationMode::Idle),
+
+            hash_ctx: Cell::new(SHA256_INIT_VALUE),
+            hash_total_size: Cell::new(0),
+        }
+    }
+
+    fn enable(&self) {
+        self.power.enable.write(bitfields::Task::ENABLE::SET);
+        for _i in 1..10 {
+            let read_signature = self.registers.host_rgf.signature.get();
+            if read_signature != CC310_SIGNATURE {
+                #[cfg(debug_assertions)]
+                rprintln!(
+                    "[loop {}] Invalid CC310 signature. Expected {}, got {}\n",
+                    _i,
+                    CC310_SIGNATURE,
+                    read_signature
+                );
+            } else {
+                break;
+            }
+        }
+        if self.registers.host_rgf.signature.get() != CC310_SIGNATURE {
+            panic!("Failed to initialize CC310");
+        }
+        // Make sure everything is set to little endian
+        self.registers.host_rgf.endian.write(
+            bitfields::RgfEndianness::DOUT_WR_BG::LittleEndian
+                + bitfields::RgfEndianness::DIN_RD_BG::LittleEndian
+                + bitfields::RgfEndianness::DOUT_WR_WBG::LittleEndian
+                + bitfields::RgfEndianness::DIN_RD_WBG::LittleEndian,
+        );
+        // Always start the clock for DMA engine. It's too hard to keep
+        // track of which submodule needs DMA otherwise.
+        self.registers
+            .misc
+            .dma_clk_enable
+            .write(bitfields::Task::ENABLE::SET);
+        self.registers.host_rgf.interrupt_mask.write(
+            bitfields::Interrupts::SRAM_TO_DIN::CLEAR
+                + bitfields::Interrupts::DOUT_TO_SRAM::CLEAR
+                + bitfields::Interrupts::MEM_TO_DIN::CLEAR
+                + bitfields::Interrupts::DOUT_TO_MEM::CLEAR
+                + bitfields::Interrupts::AXI_ERROR::SET
+                + bitfields::Interrupts::PKA_EXP::SET
+                + bitfields::Interrupts::RNG::SET
+                + bitfields::Interrupts::SYM_DMA_COMPLETED::CLEAR,
+        );
+    }
+
+    fn disable(&self) {
+        self.registers.host_rgf.interrupt_mask.set(0);
+        self.power.enable.write(bitfields::Task::ENABLE::CLEAR);
+        self.registers
+            .misc
+            .dma_clk_enable
+            .write(bitfields::Task::ENABLE::CLEAR);
+    }
+
+    fn clear_data(&self) {
+        let mut ctx = self.hash_ctx.get();
+        ctx.iter_mut().for_each(|b| *b = 0);
+        self.hash_ctx.set(ctx);
+        self.hash_total_size.set(0);
+    }
+
+    /// Adds data to the current hash computation.
+    ///
+    /// You have to know in advance if is this is going to be the last block, and indicate that
+    /// correctly. Sizes of chunks before the last need to be multiples of 64.
+    pub fn update(&self, data: &[u8], is_last_block: bool) {
+        // Start CryptoCell
+        self.enable();
+
+        while self.registers.ctrl.hash_busy.is_set(bitfields::Busy::BUSY) {}
+        while self
+            .registers
+            .ctrl
+            .crypto_busy
+            .is_set(bitfields::Busy::BUSY)
+        {}
+        while self
+            .registers
+            .din
+            .mem_dma_busy
+            .is_set(bitfields::Busy::BUSY)
+        {}
+
+        // Start HASH module and configure it
+        self.current_op.set(OperationMode::Hash);
+        self.registers
+            .misc
+            .hash_clk_enable
+            .write(bitfields::Task::ENABLE::SET);
+        self.registers
+            .ctrl
+            .crypto_ctl
+            .write(bitfields::CryptoMode::MODE::Hash);
+        self.registers
+            .hash
+            .padding
+            .write(bitfields::Task::ENABLE::SET);
+        let size = self.hash_total_size.get();
+        self.registers.hash.hash_len_lsb.set(size as u32);
+        self.registers
+            .hash
+            .hash_len_msb
+            .set(size.wrapping_shr(32) as u32);
+        self.registers
+            .hash
+            .control
+            .set(DigestAlgorithm::Sha256 as u32);
+
+        // Digest must be set backwards because writing to HASH[0]
+        // starts computation
+        let mut digest = self.hash_ctx.get();
+        for i in (0..digest.len()).rev() {
+            self.registers.hash.hash[i].set(digest[i]);
+        }
+        while self.registers.ctrl.hash_busy.is_set(bitfields::Busy::BUSY) {}
+
+        // Process data
+        if !data.is_empty() {
+            if is_last_block {
+                self.registers
+                    .hash
+                    .auto_hw_padding
+                    .write(bitfields::Task::ENABLE::SET);
+            }
+            self.registers.din.src_lli_word0.set(data.as_ptr() as u32);
+            self.registers
+                .din
+                .src_lli_word1
+                .write(bitfields::LliWord1::BYTES_NUM.val(data.len() as u32));
+            while !self
+                .registers
+                .host_rgf
+                .interrupts
+                .is_set(bitfields::Interrupts::MEM_TO_DIN)
+            {}
+            self.registers
+                .host_rgf
+                .interrupt_clear
+                .write(bitfields::Interrupts::MEM_TO_DIN::SET);
+        } else {
+            // use DO_PAD to complete padding of previous operation
+            self.registers
+                .hash
+                .pad_config
+                .write(bitfields::PaddingConfig::DO_PAD::SET);
+        }
+        while self
+            .registers
+            .ctrl
+            .crypto_busy
+            .is_set(bitfields::Busy::BUSY)
+        {}
+        while self
+            .registers
+            .din
+            .mem_dma_busy
+            .is_set(bitfields::Busy::BUSY)
+        {}
+
+        // Update context and total size
+        for i in (0..digest.len()).rev() {
+            digest[i] = self.registers.hash.hash[i].get();
+        }
+        self.hash_ctx.set(digest);
+        let new_size: u64 = ((self.registers.hash.hash_len_msb.get() as u64) << 32)
+            + (self.registers.hash.hash_len_lsb.get() as u64);
+        self.hash_total_size.set(new_size);
+
+        // Disable HASH module
+        self.registers
+            .hash
+            .padding
+            .write(bitfields::Task::ENABLE::SET);
+        self.registers
+            .hash
+            .auto_hw_padding
+            .write(bitfields::Task::ENABLE::CLEAR);
+        self.registers
+            .hash
+            .pad_config
+            .write(bitfields::PaddingConfig::DO_PAD::CLEAR);
+        while self
+            .registers
+            .ctrl
+            .crypto_busy
+            .is_set(bitfields::Busy::BUSY)
+        {}
+        self.registers
+            .misc
+            .hash_clk_enable
+            .write(bitfields::Task::ENABLE::CLEAR);
+
+        self.disable();
+    }
+
+    /// Clears the data for potential reuse, and returns the result.
+    pub fn finalize_and_clear(&self) -> [u8; 32] {
+        use byteorder::{BigEndian, ByteOrder};
+        let words = self.hash_ctx.get();
+        let mut bytes = [0u8; 32];
+        for (i, word) in words.iter().enumerate() {
+            BigEndian::write_u32(&mut bytes[4 * i..4 * i + 4], *word);
+        }
+        self.clear_data();
+        bytes
+    }
+}

bootloader/src/main.rs

@@ -1,4 +1,4 @@
-// Copyright 2021 Google LLC
+// Copyright 2021-2022 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -15,6 +15,11 @@
 #![no_main]
 #![no_std]
 
+mod bitfields;
+mod crypto_cell;
+mod registers;
+mod static_ref;
+
 extern crate cortex_m;
 extern crate cortex_m_rt as rt;
 
@@ -69,7 +74,7 @@ struct BootPartition {
 }
 
 impl BootPartition {
-    const _FIRMWARE_LENGTH: usize = 0x00040000;
+    const FIRMWARE_LENGTH: usize = 0x00040000;
 
     /// Reads the metadata, returns the timestamp if all checks pass.
     pub fn read_timestamp(&self) -> Result<u32, ()> {
@@ -93,18 +98,40 @@ impl BootPartition {
         Ok(metadata.timestamp)
     }
 
-    /// Placeholder for the SHA256 implementation.
+    /// Computes the SHA256 of metadata information and partition data.
     ///
-    /// TODO implemented in next PR
+    /// Assumes that firmware address and length are divisible by the page size.
-    /// Without it, the bootloader will never boot anything.
+    /// This is the hardware implementation on the cryptocell.
-    fn compute_upgrade_hash(&self, _metadata_page: &[u8]) -> [u8; 32] {
+    #[allow(clippy::assertions_on_constants)]
-        [0; 32]
+    fn compute_upgrade_hash(&self, metadata_page: &[u8]) -> [u8; 32] {
+        debug_assert!(self.firmware_address % PAGE_SIZE == 0);
+        debug_assert!(BootPartition::FIRMWARE_LENGTH % PAGE_SIZE == 0);
+        let cc310 = crypto_cell::CryptoCell310::new();
+        for page_offset in (0..BootPartition::FIRMWARE_LENGTH).step_by(PAGE_SIZE) {
+            let page = unsafe { read_page(self.firmware_address + page_offset) };
+            cc310.update(&page, false);
+        }
+        cc310.update(&metadata_page[32..Metadata::DATA_LEN], true);
+        cc310.finalize_and_clear()
     }
 
     /// Jump to the firmware.
     pub fn boot(&self) -> ! {
         let address = self.firmware_address;
 
+        // Clear any pending Cryptocell interrupt in NVIC
+        let peripherals = cortex_m::Peripherals::take().unwrap();
+        unsafe {
+            // We could only clear cryptocell interrupts, but let's clean up before booting.
+            // Example code to clear more specifically:
+            // const CC310_IRQ: u16 = 42;
+            // peripherals.NVIC.icpr[usize::from(CC310_IRQ / 32)].write(1 << (CC310_IRQ % 32));
+            peripherals.NVIC.icer[0].write(0xffff_ffff);
+            peripherals.NVIC.icpr[0].write(0xffff_ffff);
+            peripherals.NVIC.icer[1].write(0xffff_ffff);
+            peripherals.NVIC.icpr[1].write(0xffff_ffff);
+        }
+
         #[cfg(debug_assertions)]
         rprintln!("Boot jump to {:08X}", address);
         let address_pointer = address as *const u32;

bootloader/src/registers.rs

@@ -0,0 +1,139 @@
+// Copyright 2020-2022 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::bitfields::{
+    Busy, CryptoMode, HashControl, Interrupts, LliWord1, PaddingConfig, RgfEndianness, Task,
+};
+use tock_registers::{
+    register_structs,
+    registers::{ReadOnly, ReadWrite, WriteOnly},
+};
+
+register_structs! {
+    pub CryptoCellControlRegisters {
+        /// Defines the cryptographic flow
+        (0x0000 => pub crypto_ctl: WriteOnly<u32, CryptoMode::Register>),
+        (0x0004 => _reserved0),
+        /// This register is set whent the cryptographic core is busy
+        (0x0010 => pub crypto_busy: ReadOnly<u32, Busy::Register>),
+        (0x0014 => _reserved1),
+        /// This register is set when the Hash engine is busy
+        (0x001C => pub hash_busy: ReadOnly<u32, Busy::Register>),
+        (0x0020 => @END),
+    }
+}
+
+register_structs! {
+    pub CryptoCellDinRegisters {
+        (0x0000 => _reserved0),
+        /// Indicates whether memoty (AXI) source DMA (DIN) is busy
+        (0x0020 => pub mem_dma_busy: ReadOnly<u32, Busy::Register>),
+        (0x0024 => _reserved1),
+        /// This register is used in direct LLI mode - holds the location of the data source
+        /// in the memory (AXI)
+        (0x0028 => pub src_lli_word0: WriteOnly<u32>),
+        /// This register is used in direct LLI mode - holds the number of bytes to be read
+        /// from the memory (AXI).
+        /// Writing to this register triggers the DMA.
+        (0x002C => pub src_lli_word1: WriteOnly<u32, LliWord1::Register>),
+        (0x0030 => @END),
+    }
+}
+
+register_structs! {
+    pub CryptoCellHashRegisters {
+        /// Write initial hash value or read final hash value
+        (0x0000 => pub hash: [ReadWrite<u32>; 9]),
+        (0x0024 => _reserved0),
+        /// HW padding automatically activated by engine.
+        /// For the special case of ZERO bytes data vector this register should not be used! instead use HASH_PAD_CFG
+        (0x0044 => pub auto_hw_padding: WriteOnly<u32, Task::Register>),
+        (0x0048 => _reserved1),
+        /// Selects which HASH mode to run
+        (0x0180 => pub control: ReadWrite<u32, HashControl::Register>),
+        /// This register enables the hash hw padding.
+        (0x0184 => pub padding: ReadWrite<u32, Task::Register>),
+        /// HASH_PAD_CFG Register.
+        (0x0188 => pub pad_config: ReadWrite<u32, PaddingConfig::Register>),
+        /// This register hold the length of current hash operation
+        (0x018C => pub hash_len_lsb: ReadWrite<u32>),
+        /// This register hold the length of current hash operation
+        (0x0190 => pub hash_len_msb: ReadWrite<u32>),
+        (0x0194 => @END),
+    }
+}
+
+register_structs! {
+    pub CryptoCellHostRgfRegisters {
+        /// The Interrupt Request register.
+        /// Each bit of this register holds the interrupt status of a single interrupt source.
+        (0x0000 => pub interrupts: ReadOnly<u32, Interrupts::Register>),
+        /// The Interrupt Mask register. Each bit of this register holds the mask of a single
+        /// interrupt source.
+        (0x0004 => pub interrupt_mask: ReadWrite<u32, Interrupts::Register>),
+        /// Interrupt Clear Register
+        (0x0008 => pub interrupt_clear: WriteOnly<u32, Interrupts::Register>),
+        /// This register defines the endianness of the Host-accessible registers.
+        (0x000C => pub endian: ReadWrite<u32, RgfEndianness::Register>),
+        (0x0010 => _reserved0),
+        /// This register holds the CryptoCell product signature.
+        (0x0024 => pub signature: ReadOnly<u32>),
+        (0x0028 => @END),
+    }
+}
+
+register_structs! {
+    pub CryptoCellMiscRegisters {
+        (0x0000 => _reserved0),
+        /// The HASH clock enable register
+        (0x0018 => pub hash_clk_enable: ReadWrite<u32, Task::Register>),
+        /// The PKA clock enable register
+        (0x001C => _reserved1),
+        /// The DMA clock enable register
+        (0x0020 => pub dma_clk_enable: ReadWrite<u32, Task::Register>),
+        /// the CryptoCell clocks' status register
+        (0x0024 => @END),
+    }
+}
+
+register_structs! {
+    pub NordicCC310Registers {
+        (0x0000 => pub enable: ReadWrite<u32, Task::Register>),
+        (0x0004 => @END),
+    },
+
+    pub CryptoCellRegisters {
+        (0x0000 => _reserved0),
+        /// HASH registers
+        /// - Base address: 0x0640
+        (0x0640 => pub hash: CryptoCellHashRegisters),
+        (0x07D4 => _reserved1),
+        /// Misc registers
+        /// - Base address: 0x0800
+        (0x0800 => pub misc: CryptoCellMiscRegisters),
+        (0x0824 => _reserved2),
+        /// CryptoCell control registers
+        /// - Base address: 0x0900
+        (0x0900 => pub ctrl: CryptoCellControlRegisters),
+        (0x0920 => _reserved3),
+        /// HOST_RGF registers
+        /// - Base address: 0x0A00
+        (0x0A00 => pub host_rgf: CryptoCellHostRgfRegisters),
+        (0x0A28 => _reserved4),
+        /// DIN registers
+        /// - Base address: 0x0C00
+        (0x0C00 => pub din: CryptoCellDinRegisters),
+        (0x0C30 => @END),
+    }
+}

bootloader/src/static_ref.rs

@@ -0,0 +1,46 @@
+//! Wrapper type for safe pointers to static memory.
+//!
+//! Imported from:
+//! https://github.com/tock/tock/blob/master/kernel/src/utilities/static_ref.rs
+
+use core::ops::Deref;
+
+/// A pointer to statically allocated mutable data such as memory mapped I/O
+/// registers.
+///
+/// This is a simple wrapper around a raw pointer that encapsulates an unsafe
+/// dereference in a safe manner. It serve the role of creating a `&'static T`
+/// given a raw address and acts similarly to `extern` definitions, except
+/// `StaticRef` is subject to module and crate boundaries, while `extern`
+/// definitions can be imported anywhere.
+#[derive(Debug)]
+pub struct StaticRef<T> {
+    ptr: *const T,
+}
+
+impl<T> StaticRef<T> {
+    /// Create a new `StaticRef` from a raw pointer
+    ///
+    /// ## Safety
+    ///
+    /// Callers must pass in a reference to statically allocated memory which
+    /// does not overlap with other values.
+    pub const unsafe fn new(ptr: *const T) -> StaticRef<T> {
+        StaticRef { ptr }
+    }
+}
+
+impl<T> Clone for StaticRef<T> {
+    fn clone(&self) -> Self {
+        StaticRef { ptr: self.ptr }
+    }
+}
+
+impl<T> Copy for StaticRef<T> {}
+
+impl<T> Deref for StaticRef<T> {
+    type Target = T;
+    fn deref(&self) -> &'static T {
+        unsafe { &*self.ptr }
+    }
+}

fuzz/fuzz_helper/src/lib.rs

@@ -25,14 +25,12 @@ use ctap2::ctap::command::{
 };
 use ctap2::ctap::hid::receive::MessageAssembler;
 use ctap2::ctap::hid::send::HidPacketIterator;
-use ctap2::ctap::hid::{ChannelID, HidPacket, Message};
+use ctap2::ctap::hid::{ChannelID, CtapHidCommand, HidPacket, Message};
 use ctap2::env::test::TestEnv;
 use ctap2::Ctap;
 use libtock_drivers::timer::{ClockValue, Timestamp};
 
-const COMMAND_INIT: u8 = 0x06;
 const CHANNEL_BROADCAST: ChannelID = [0xFF, 0xFF, 0xFF, 0xFF];
-const PACKET_TYPE_MASK: u8 = 0x80;
 
 const CLOCK_FREQUENCY_HZ: usize = 32768;
 const DUMMY_TIMESTAMP: Timestamp<isize> = Timestamp::from_ms(0);
@@ -53,13 +51,14 @@ fn raw_to_message(data: &[u8]) -> Message {
         cid[..data.len()].copy_from_slice(data);
         Message {
             cid,
-            cmd: 0,
+            // Arbitrary command.
+            cmd: CtapHidCommand::Cbor,
             payload: vec![],
         }
     } else {
         Message {
             cid: array_ref!(data, 0, 4).clone(),
-            cmd: data[4],
+            cmd: CtapHidCommand::from(data[4]),
             payload: data[5..].to_vec(),
         }
     }
@@ -71,7 +70,7 @@ fn initialize(ctap: &mut Ctap<TestEnv>) -> ChannelID {
     let nonce = vec![0x12, 0x34, 0x56, 0x78, 0x9A, 0xBC, 0xDE, 0xF0];
     let message = Message {
         cid: CHANNEL_BROADCAST,
-        cmd: COMMAND_INIT,
+        cmd: CtapHidCommand::Init,
         payload: nonce,
     };
     let mut assembler_reply = MessageAssembler::new();
@@ -168,7 +167,7 @@ pub fn process_ctap_specific_type(data: &[u8], input_type: InputType) {
 
 // Splits the given data as HID packets and reassembles it, verifying that the original input message is reconstructed.
 pub fn split_assemble_hid_packets(data: &[u8]) {
-    let mut message = raw_to_message(data);
+    let message = raw_to_message(data);
     if let Some(hid_packet_iterator) = HidPacketIterator::new(message.clone()) {
         let mut assembler = MessageAssembler::new();
         let packets: Vec<HidPacket> = hid_packet_iterator.collect();
@@ -176,7 +175,6 @@ pub fn split_assemble_hid_packets(data: &[u8]) {
             for packet in first_packets {
                 assert_eq!(assembler.parse_packet(packet, DUMMY_TIMESTAMP), Ok(None));
             }
-            message.cmd &= !PACKET_TYPE_MASK;
             assert_eq!(
                 assembler.parse_packet(last_packet, DUMMY_TIMESTAMP),
                 Ok(Some(message))

fuzzing_setup.sh

@@ -20,4 +20,4 @@ done_text="$(tput bold)DONE.$(tput sgr0)"
 set -e
 
 # Install cargo-fuzz library.
-cargo +stable install cargo-fuzz
+cargo +stable install cargo-fuzz --version 0.10.2

src/ctap/hid/mod.rs

@@ -32,13 +32,50 @@ use core::fmt::Write;
 use libtock_drivers::console::Console;
 use libtock_drivers::timer::{ClockValue, Duration, Timestamp};
 
-// CTAP specification (version 20190130) section 8.1
-// TODO: Channel allocation, section 8.1.3?
-// TODO: Transaction timeout, section 8.1.5.2
-
 pub type HidPacket = [u8; 64];
 pub type ChannelID = [u8; 4];
 
+/// CTAPHID commands
+///
+/// See section 11.2.9. of FIDO 2.1 (2021-06-15).
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum CtapHidCommand {
+    Ping = 0x01,
+    Msg = 0x03,
+    // Lock is optional and may be used in the future.
+    Lock = 0x04,
+    Init = 0x06,
+    Wink = 0x08,
+    Cbor = 0x10,
+    Cancel = 0x11,
+    Keepalive = 0x3B,
+    Error = 0x3F,
+    // VendorFirst and VendorLast describe a range, and are not commands themselves.
+    _VendorFirst = 0x40,
+    _VendorLast = 0x7F,
+}
+
+impl From<u8> for CtapHidCommand {
+    fn from(cmd: u8) -> Self {
+        match cmd {
+            x if x == CtapHidCommand::Ping as u8 => CtapHidCommand::Ping,
+            x if x == CtapHidCommand::Msg as u8 => CtapHidCommand::Msg,
+            x if x == CtapHidCommand::Lock as u8 => CtapHidCommand::Lock,
+            x if x == CtapHidCommand::Init as u8 => CtapHidCommand::Init,
+            x if x == CtapHidCommand::Wink as u8 => CtapHidCommand::Wink,
+            x if x == CtapHidCommand::Cbor as u8 => CtapHidCommand::Cbor,
+            x if x == CtapHidCommand::Cancel as u8 => CtapHidCommand::Cancel,
+            x if x == CtapHidCommand::Keepalive as u8 => CtapHidCommand::Keepalive,
+            // This includes the actual error code 0x3F. Error is not used for incoming packets in
+            // the specification, so we can safely reuse it for unknown bytes.
+            _ => CtapHidCommand::Error,
+        }
+    }
+}
+
+/// Describes the structure of a parsed HID packet.
+///
+/// A packet is either an Init or a Continuation packet.
 pub enum ProcessedPacket<'a> {
     InitPacket {
         cmd: u8,
@@ -51,72 +88,79 @@ pub enum ProcessedPacket<'a> {
     },
 }
 
-// An assembled CTAPHID command.
+/// An assembled CTAPHID command.
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct Message {
     // Channel ID.
     pub cid: ChannelID,
     // Command.
-    pub cmd: u8,
+    pub cmd: CtapHidCommand,
     // Bytes of the message.
     pub payload: Vec<u8>,
 }
 
+/// A keepalive packet reports the reason why a command does not finish.
+#[allow(dead_code)]
+pub enum KeepaliveStatus {
+    Processing = 0x01,
+    UpNeeded = 0x02,
+}
+
+/// Holds all state for receiving and sending HID packets.
+///
+/// This includes
+/// - state from not fully processed messages,
+/// - all allocated channels,
+/// - information about requested winks.
+///
+/// The wink information can be polled to decide to i.e. blink LEDs.
+///
+/// To process a packet and receive the response, you can call `process_hid_packet`.
+/// If you want more control, you can also do the processing in steps:
+///
+/// 1.  `HidPacket` -> `Option<Message>`
+/// 2.  `Option<Message>` -> `Message`
+/// 3.  `Message` -> `Message`
+/// 4.  `Message` -> `HidPacketIterator`
+///
+/// These steps correspond to:
+///
+/// 1.  `parse_packet` assembles the message and preprocesses all pure HID commands and errors.
+/// 2.  If you didn't receive any message or preprocessing discarded it, stop.
+/// 3.  `process_message` handles all protocol interactions.
+/// 4.  `split_message` creates packets out of the response message.
 pub struct CtapHid {
     assembler: MessageAssembler,
-    // The specification (version 20190130) only requires unique CIDs ; the allocation algorithm is
+    // The specification only requires unique CIDs, the allocation algorithm is vendor specific.
-    // vendor specific.
     // We allocate them incrementally, that is all `cid` such that 1 <= cid <= allocated_cids are
     // allocated.
     // In packets, the ID encoding is Big Endian to match what is used throughout CTAP (with the
     // u32::to/from_be_bytes methods).
+    // TODO(kaczmarczyck) We might want to limit or timeout open channels.
     allocated_cids: usize,
     pub(crate) wink_permission: TimedPermission,
 }
 
-#[allow(dead_code)]
-pub enum KeepaliveStatus {
-    Processing,
-    UpNeeded,
-}
-
-#[allow(dead_code)]
-// TODO(kaczmarczyck) disable the warning in the end
 impl CtapHid {
-    // CTAP specification (version 20190130) section 8.1.3
+    // We implement CTAP 2.1 from 2021-06-15. Please see section
+    // 11.2. USB Human Interface Device (USB HID)
     const CHANNEL_RESERVED: ChannelID = [0, 0, 0, 0];
     const CHANNEL_BROADCAST: ChannelID = [0xFF, 0xFF, 0xFF, 0xFF];
     const TYPE_INIT_BIT: u8 = 0x80;
     const PACKET_TYPE_MASK: u8 = 0x80;
 
-    // CTAP specification (version 20190130) section 8.1.9
-    const COMMAND_PING: u8 = 0x01;
-    const COMMAND_MSG: u8 = 0x03;
-    const COMMAND_INIT: u8 = 0x06;
-    const COMMAND_CBOR: u8 = 0x10;
-    pub const COMMAND_CANCEL: u8 = 0x11;
-    const COMMAND_KEEPALIVE: u8 = 0x3B;
-    const COMMAND_ERROR: u8 = 0x3F;
-    // TODO: optional lock command
-    const COMMAND_LOCK: u8 = 0x04;
-    const COMMAND_WINK: u8 = 0x08;
-    const COMMAND_VENDOR_FIRST: u8 = 0x40;
-    const COMMAND_VENDOR_LAST: u8 = 0x7F;
-
-    // CTAP specification (version 20190130) section 8.1.9.1.6
     const ERR_INVALID_CMD: u8 = 0x01;
-    const ERR_INVALID_PAR: u8 = 0x02;
+    const _ERR_INVALID_PAR: u8 = 0x02;
     const ERR_INVALID_LEN: u8 = 0x03;
     const ERR_INVALID_SEQ: u8 = 0x04;
     const ERR_MSG_TIMEOUT: u8 = 0x05;
     const ERR_CHANNEL_BUSY: u8 = 0x06;
-    const ERR_LOCK_REQUIRED: u8 = 0x0A;
+    const _ERR_LOCK_REQUIRED: u8 = 0x0A;
     const ERR_INVALID_CHANNEL: u8 = 0x0B;
-    const ERR_OTHER: u8 = 0x7F;
+    const _ERR_OTHER: u8 = 0x7F;
 
-    // CTAP specification (version 20190130) section 8.1.9.1.3
+    // See section 11.2.9.1.3. CTAPHID_INIT (0x06).
     const PROTOCOL_VERSION: u8 = 2;
-
     // The device version number is vendor-defined.
     const DEVICE_VERSION_MAJOR: u8 = 1;
     const DEVICE_VERSION_MINOR: u8 = 0;
@@ -124,6 +168,7 @@ impl CtapHid {
 
     const CAPABILITY_WINK: u8 = 0x01;
     const CAPABILITY_CBOR: u8 = 0x04;
+    #[cfg(not(feature = "with_ctap1"))]
     const CAPABILITY_NMSG: u8 = 0x08;
     // Capabilitites currently supported by this device.
     #[cfg(feature = "with_ctap1")]
@@ -136,6 +181,7 @@ impl CtapHid {
     const TIMEOUT_DURATION: Duration<isize> = Duration::from_ms(100);
     const WINK_TIMEOUT_DURATION: Duration<isize> = Duration::from_ms(5000);
 
+    /// Creates a new idle HID state.
     pub fn new() -> CtapHid {
         CtapHid {
             assembler: MessageAssembler::new(),
@@ -144,16 +190,26 @@ impl CtapHid {
         }
     }
 
-    // Process an incoming USB HID packet, and optionally returns a list of outgoing packets to
+    /// Parses a packet, and preprocesses some messages and errors.
-    // send as a reply.
+    ///
-    pub fn process_hid_packet(
+    /// The preprocessed commands are:
-        &mut self,
+    /// - INIT
-        env: &mut impl Env,
+    /// - CANCEL
-        packet: &HidPacket,
+    /// - ERROR
-        clock_value: ClockValue,
+    /// - Unknown and unexpected commands like KEEPALIVE
-        ctap_state: &mut CtapState,
+    /// - LOCK is not implemented and currently treated like an unknown command
-    ) -> HidPacketIterator {
+    ///
-        // TODO: Send COMMAND_KEEPALIVE every 100ms?
+    /// Commands that may still be processed:
+    /// - PING
+    /// - MSG
+    /// - WINK
+    /// - CBOR
+    ///
+    /// You may ignore PING, it's behaving correctly by default (input == output).
+    /// Ignoring the others is incorrect behavior. You have to at least replace them with an error
+    /// message:
+    /// `CtapHid::error_message(message.cid, CtapHid::ERR_INVALID_CMD)`
+    pub fn parse_packet(&mut self, packet: &HidPacket, clock_value: ClockValue) -> Option<Message> {
         match self
             .assembler
             .parse_packet(packet, Timestamp::<isize>::from_clock_value(clock_value))
@@ -161,72 +217,70 @@ impl CtapHid {
             Ok(Some(message)) => {
                 #[cfg(feature = "debug_ctap")]
                 writeln!(&mut Console::new(), "Received message: {:02x?}", message).unwrap();
+                self.preprocess_message(message)
+            }
+            Ok(None) => {
+                // Waiting for more packets to assemble the message, nothing to send for now.
+                None
+            }
+            Err((cid, error)) => {
+                if !self.is_allocated_channel(cid)
+                    && error != receive::Error::UnexpectedContinuation
+                {
+                    Some(CtapHid::error_message(cid, CtapHid::ERR_INVALID_CHANNEL))
+                } else {
+                    match error {
+                        receive::Error::UnexpectedChannel => {
+                            Some(CtapHid::error_message(cid, CtapHid::ERR_CHANNEL_BUSY))
+                        }
+                        receive::Error::UnexpectedInit => {
+                            // TODO: Should we send another error code in this case?
+                            // Technically, we were expecting a sequence number and got another
+                            // byte, although the command/seqnum bit has higher-level semantics
+                            // than sequence numbers.
+                            Some(CtapHid::error_message(cid, CtapHid::ERR_INVALID_SEQ))
+                        }
+                        receive::Error::UnexpectedContinuation => {
+                            // CTAP specification (version 20190130) section 8.1.5.4
+                            // Spurious continuation packets will be ignored.
+                            None
+                        }
+                        receive::Error::UnexpectedSeq => {
+                            Some(CtapHid::error_message(cid, CtapHid::ERR_INVALID_SEQ))
+                        }
+                        receive::Error::UnexpectedLen => {
+                            Some(CtapHid::error_message(cid, CtapHid::ERR_INVALID_LEN))
+                        }
+                        receive::Error::Timeout => {
+                            Some(CtapHid::error_message(cid, CtapHid::ERR_MSG_TIMEOUT))
+                        }
+                    }
+                }
+            }
+        }
+    }
 
+    /// Processes HID-only commands of a message and returns an outgoing message if necessary.
+    ///
+    /// The preprocessed commands are:
+    /// - INIT
+    /// - CANCEL
+    /// - ERROR
+    /// - Unknown and unexpected commands like KEEPALIVE
+    /// - LOCK is not implemented and currently treated like an unknown command
+    fn preprocess_message(&mut self, message: Message) -> Option<Message> {
         let cid = message.cid;
         if !self.has_valid_channel(&message) {
-                    #[cfg(feature = "debug_ctap")]
+            return Some(CtapHid::error_message(cid, CtapHid::ERR_INVALID_CHANNEL));
-                    writeln!(&mut Console::new(), "Invalid channel: {:02x?}", cid).unwrap();
-                    return CtapHid::error_message(cid, CtapHid::ERR_INVALID_CHANNEL);
         }
-                // If another command arrives, stop winking to prevent accidential button touches.
-                self.wink_permission = TimedPermission::waiting();
 
         match message.cmd {
-                    // CTAP specification (version 20190130) section 8.1.9.1.1
+            CtapHidCommand::Msg => Some(message),
-                    CtapHid::COMMAND_MSG => {
+            CtapHidCommand::Cbor => Some(message),
-                        // If we don't have CTAP1 backward compatibilty, this command is invalid.
+            // CTAP 2.1 from 2021-06-15, section 11.2.9.1.3.
-                        #[cfg(not(feature = "with_ctap1"))]
+            CtapHidCommand::Init => {
-                        return CtapHid::error_message(cid, CtapHid::ERR_INVALID_CMD);
-
-                        #[cfg(feature = "with_ctap1")]
-                        match ctap1::Ctap1Command::process_command(
-                            env,
-                            &message.payload,
-                            ctap_state,
-                            clock_value,
-                        ) {
-                            Ok(payload) => CtapHid::ctap1_success_message(cid, &payload),
-                            Err(ctap1_status_code) => {
-                                CtapHid::ctap1_error_message(cid, ctap1_status_code)
-                            }
-                        }
-                    }
-                    // CTAP specification (version 20190130) section 8.1.9.1.2
-                    CtapHid::COMMAND_CBOR => {
-                        // CTAP specification (version 20190130) section 8.1.5.1
-                        // Each transaction is atomic, so we process the command directly here and
-                        // don't handle any other packet in the meantime.
-                        // TODO: Send keep-alive packets in the meantime.
-                        let response =
-                            ctap_state.process_command(env, &message.payload, cid, clock_value);
-                        if let Some(iterator) = CtapHid::split_message(Message {
-                            cid,
-                            cmd: CtapHid::COMMAND_CBOR,
-                            payload: response,
-                        }) {
-                            iterator
-                        } else {
-                            // Handle the case of a payload > 7609 bytes.
-                            // Although this shouldn't happen if the FIDO2 commands are implemented
-                            // correctly, we reply with a vendor specific code instead of silently
-                            // ignoring the error.
-                            //
-                            // The error payload that we send instead is 1 <= 7609 bytes, so it is
-                            // safe to unwrap() the result.
-                            CtapHid::split_message(Message {
-                                cid,
-                                cmd: CtapHid::COMMAND_CBOR,
-                                payload: vec![
-                                    Ctap2StatusCode::CTAP2_ERR_VENDOR_INTERNAL_ERROR as u8,
-                                ],
-                            })
-                            .unwrap()
-                        }
-                    }
-                    // CTAP specification (version 20190130) section 8.1.9.1.3
-                    CtapHid::COMMAND_INIT => {
                 if message.payload.len() != 8 {
-                            return CtapHid::error_message(cid, CtapHid::ERR_INVALID_LEN);
+                    return Some(CtapHid::error_message(cid, CtapHid::ERR_INVALID_LEN));
                 }
 
                 let new_cid = if cid == CtapHid::CHANNEL_BROADCAST {
@@ -247,95 +301,116 @@ impl CtapHid {
                 payload[15] = CtapHid::DEVICE_VERSION_BUILD;
                 payload[16] = CtapHid::CAPABILITIES;
 
-                        // This unwrap is safe because the payload length is 17 <= 7609 bytes.
+                Some(Message {
-                        CtapHid::split_message(Message {
                     cid,
-                            cmd: CtapHid::COMMAND_INIT,
+                    cmd: CtapHidCommand::Init,
                     payload,
                 })
-                        .unwrap()
             }
-                    // CTAP specification (version 20190130) section 8.1.9.1.4
+            // CTAP 2.1 from 2021-06-15, section 11.2.9.1.4.
-                    CtapHid::COMMAND_PING => {
+            CtapHidCommand::Ping => {
                 // Pong the same message.
-                        // This unwrap is safe because if we could parse the incoming message, it's
+                Some(message)
-                        // payload length must be <= 7609 bytes.
-                        CtapHid::split_message(message).unwrap()
             }
-                    // CTAP specification (version 20190130) section 8.1.9.1.5
+            // CTAP 2.1 from 2021-06-15, section 11.2.9.1.5.
-                    CtapHid::COMMAND_CANCEL => {
+            CtapHidCommand::Cancel => {
                 // Authenticators MUST NOT reply to this message.
                 // CANCEL is handled during user presence checks in main.
-                        HidPacketIterator::none()
+                None
             }
-                    // Optional commands
+            CtapHidCommand::Wink => Some(message),
-                    // CTAP specification (version 20190130) section 8.1.9.2.1
-                    CtapHid::COMMAND_WINK => {
-                        if !message.payload.is_empty() {
-                            return CtapHid::error_message(cid, CtapHid::ERR_INVALID_LEN);
-                        }
-                        self.wink_permission =
-                            TimedPermission::granted(clock_value, CtapHid::WINK_TIMEOUT_DURATION);
-                        CtapHid::split_message(Message {
-                            cid,
-                            cmd: CtapHid::COMMAND_WINK,
-                            payload: vec![],
-                        })
-                        .unwrap()
-                    }
-                    // CTAP specification (version 20190130) section 8.1.9.2.2
-                    // TODO: implement LOCK
             _ => {
                 // Unknown or unsupported command.
-                        CtapHid::error_message(cid, CtapHid::ERR_INVALID_CMD)
+                Some(CtapHid::error_message(cid, CtapHid::ERR_INVALID_CMD))
             }
         }
     }
-            Ok(None) => {
+
-                // Waiting for more packets to assemble the message, nothing to send for now.
+    /// Processes a message's commands that affect the protocol outside HID.
-                HidPacketIterator::none()
+    pub fn process_message(
+        &mut self,
+        env: &mut impl Env,
+        message: Message,
+        clock_value: ClockValue,
+        ctap_state: &mut CtapState,
+    ) -> Message {
+        // If another command arrives, stop winking to prevent accidential button touches.
+        self.wink_permission = TimedPermission::waiting();
+
+        let cid = message.cid;
+        match message.cmd {
+            // CTAP 2.1 from 2021-06-15, section 11.2.9.1.1.
+            CtapHidCommand::Msg => {
+                // If we don't have CTAP1 backward compatibilty, this command is invalid.
+                #[cfg(not(feature = "with_ctap1"))]
+                return CtapHid::error_message(cid, CtapHid::ERR_INVALID_CMD);
+
+                #[cfg(feature = "with_ctap1")]
+                match ctap1::Ctap1Command::process_command(
+                    env,
+                    &message.payload,
+                    ctap_state,
+                    clock_value,
+                ) {
+                    Ok(payload) => CtapHid::ctap1_success_message(cid, &payload),
+                    Err(ctap1_status_code) => CtapHid::ctap1_error_message(cid, ctap1_status_code),
                 }
-            Err((cid, error)) => {
+            }
-                if !self.is_allocated_channel(cid)
+            // CTAP 2.1 from 2021-06-15, section 11.2.9.1.2.
-                    && error != receive::Error::UnexpectedContinuation
+            CtapHidCommand::Cbor => {
-                {
+                // Each transaction is atomic, so we process the command directly here and
-                    CtapHid::error_message(cid, CtapHid::ERR_INVALID_CHANNEL)
+                // don't handle any other packet in the meantime.
+                // TODO: Send "Processing" type keep-alive packets in the meantime.
+                let response = ctap_state.process_command(env, &message.payload, cid, clock_value);
+                Message {
+                    cid,
+                    cmd: CtapHidCommand::Cbor,
+                    payload: response,
+                }
+            }
+            // CTAP 2.1 from 2021-06-15, section 11.2.9.2.1.
+            CtapHidCommand::Wink => {
+                if message.payload.is_empty() {
+                    self.wink_permission =
+                        TimedPermission::granted(clock_value, CtapHid::WINK_TIMEOUT_DURATION);
+                    // The response is empty like the request.
+                    message
                 } else {
-                    match error {
-                        receive::Error::UnexpectedChannel => {
-                            CtapHid::error_message(cid, CtapHid::ERR_CHANNEL_BUSY)
-                        }
-                        receive::Error::UnexpectedInit => {
-                            // TODO: Should we send another error code in this case?
-                            // Technically, we were expecting a sequence number and got another
-                            // byte, although the command/seqnum bit has higher-level semantics
-                            // than sequence numbers.
-                            CtapHid::error_message(cid, CtapHid::ERR_INVALID_SEQ)
-                        }
-                        receive::Error::UnexpectedContinuation => {
-                            // CTAP specification (version 20190130) section 8.1.5.4
-                            // Spurious continuation packets will be ignored.
-                            HidPacketIterator::none()
-                        }
-                        receive::Error::UnexpectedSeq => {
-                            CtapHid::error_message(cid, CtapHid::ERR_INVALID_SEQ)
-                        }
-                        receive::Error::UnexpectedLen => {
                     CtapHid::error_message(cid, CtapHid::ERR_INVALID_LEN)
                 }
-                        receive::Error::Timeout => {
+            }
-                            CtapHid::error_message(cid, CtapHid::ERR_MSG_TIMEOUT)
+            // All other commands have already been processed, keep them as is.
-                        }
+            _ => message,
-                    }
         }
     }
+
+    /// Processes an incoming USB HID packet, and returns an iterator for all outgoing packets.
+    pub fn process_hid_packet(
+        &mut self,
+        env: &mut impl Env,
+        packet: &HidPacket,
+        clock_value: ClockValue,
+        ctap_state: &mut CtapState,
+    ) -> HidPacketIterator {
+        if let Some(message) = self.parse_packet(packet, clock_value) {
+            let processed_message = self.process_message(env, message, clock_value, ctap_state);
+            #[cfg(feature = "debug_ctap")]
+            writeln!(
+                &mut Console::new(),
+                "Sending message: {:02x?}",
+                processed_message
+            )
+            .unwrap();
+            CtapHid::split_message(processed_message)
+        } else {
+            HidPacketIterator::none()
         }
     }
 
     fn has_valid_channel(&self, message: &Message) -> bool {
         match message.cid {
             // Only INIT commands use the broadcast channel.
-            CtapHid::CHANNEL_BROADCAST => message.cmd == CtapHid::COMMAND_INIT,
+            CtapHid::CHANNEL_BROADCAST => message.cmd == CtapHidCommand::Init,
             // Check that the channel is allocated.
             _ => self.is_allocated_channel(message.cid),
         }
@@ -345,16 +420,15 @@ impl CtapHid {
         cid != CtapHid::CHANNEL_RESERVED && u32::from_be_bytes(cid) as usize <= self.allocated_cids
     }
 
-    fn error_message(cid: ChannelID, error_code: u8) -> HidPacketIterator {
+    fn error_message(cid: ChannelID, error_code: u8) -> Message {
-        // This unwrap is safe because the payload length is 1 <= 7609 bytes.
+        Message {
-        CtapHid::split_message(Message {
             cid,
-            cmd: CtapHid::COMMAND_ERROR,
+            cmd: CtapHidCommand::Error,
             payload: vec![error_code],
-        })
+        }
-        .unwrap()
     }
 
+    /// Helper function to parse a raw packet.
     pub fn process_single_packet(packet: &HidPacket) -> (&ChannelID, ProcessedPacket) {
         let (cid, rest) = array_refs![packet, 4, 60];
         if rest[0] & CtapHid::PACKET_TYPE_MASK != 0 {
@@ -379,56 +453,65 @@ impl CtapHid {
         }
     }
 
-    fn split_message(message: Message) -> Option<HidPacketIterator> {
+    /// Splits the message and unwraps the result.
-        #[cfg(feature = "debug_ctap")]
+    ///
-        writeln!(&mut Console::new(), "Sending message: {:02x?}", message).unwrap();
+    /// Unwrapping handles the case of payload lengths > 7609 bytes. All responses are fixed
-        HidPacketIterator::new(message)
+    /// length, with the exception of:
+    /// - PING, but here output equals the (validated) input,
+    /// - CBOR, where long responses are conceivable.
+    ///
+    /// Long CBOR responses should not happen, but we might not catch all edge cases, like for
+    /// example long user names that are part of the output of an assertion. These cases should be
+    /// correctly handled by the CTAP implementation. It is therefore an internal error from the
+    /// HID perspective.
+    fn split_message(message: Message) -> HidPacketIterator {
+        let cid = message.cid;
+        HidPacketIterator::new(message).unwrap_or_else(|| {
+            // The error payload is 1 <= 7609 bytes, so unwrap() is safe.
+            HidPacketIterator::new(Message {
+                cid,
+                cmd: CtapHidCommand::Cbor,
+                payload: vec![Ctap2StatusCode::CTAP2_ERR_VENDOR_INTERNAL_ERROR as u8],
+            })
+            .unwrap()
+        })
     }
 
+    /// Generates the HID response packets for a keepalive status.
     pub fn keepalive(cid: ChannelID, status: KeepaliveStatus) -> HidPacketIterator {
-        let status_code = match status {
-            KeepaliveStatus::Processing => 1,
-            KeepaliveStatus::UpNeeded => 2,
-        };
         // This unwrap is safe because the payload length is 1 <= 7609 bytes.
         CtapHid::split_message(Message {
             cid,
-            cmd: CtapHid::COMMAND_KEEPALIVE,
+            cmd: CtapHidCommand::Keepalive,
-            payload: vec![status_code],
+            payload: vec![status as u8],
         })
-        .unwrap()
     }
 
+    /// Returns whether a wink permission is currently granted.
     pub fn should_wink(&self, now: ClockValue) -> bool {
         self.wink_permission.is_granted(now)
     }
 
     #[cfg(feature = "with_ctap1")]
-    fn ctap1_error_message(
+    fn ctap1_error_message(cid: ChannelID, error_code: ctap1::Ctap1StatusCode) -> Message {
-        cid: ChannelID,
-        error_code: ctap1::Ctap1StatusCode,
-    ) -> HidPacketIterator {
-        // This unwrap is safe because the payload length is 2 <= 7609 bytes
         let code: u16 = error_code.into();
-        CtapHid::split_message(Message {
+        Message {
             cid,
-            cmd: CtapHid::COMMAND_MSG,
+            cmd: CtapHidCommand::Msg,
             payload: code.to_be_bytes().to_vec(),
-        })
+        }
-        .unwrap()
     }
 
     #[cfg(feature = "with_ctap1")]
-    fn ctap1_success_message(cid: ChannelID, payload: &[u8]) -> HidPacketIterator {
+    fn ctap1_success_message(cid: ChannelID, payload: &[u8]) -> Message {
         let mut response = payload.to_vec();
         let code: u16 = ctap1::Ctap1StatusCode::SW_SUCCESS.into();
         response.extend_from_slice(&code.to_be_bytes());
-        CtapHid::split_message(Message {
+        Message {
             cid,
-            cmd: CtapHid::COMMAND_MSG,
+            cmd: CtapHidCommand::Msg,
             payload: response,
-        })
+        }
-        .unwrap()
     }
 }
 
@@ -478,7 +561,7 @@ mod test {
             ctap_state,
             vec![Message {
                 cid: CtapHid::CHANNEL_BROADCAST,
-                cmd: CtapHid::COMMAND_INIT,
+                cmd: CtapHidCommand::Init,
                 payload: nonce.clone(),
             }],
         );
@@ -500,7 +583,7 @@ mod test {
         for payload_len in 0..7609 {
             let message = Message {
                 cid: [0x12, 0x34, 0x56, 0x78],
-                cmd: 0x00,
+                cmd: CtapHidCommand::Cbor,
                 payload: vec![0xFF; payload_len],
             };
 
@@ -552,7 +635,7 @@ mod test {
             &mut ctap_state,
             vec![Message {
                 cid: CtapHid::CHANNEL_BROADCAST,
-                cmd: CtapHid::COMMAND_INIT,
+                cmd: CtapHidCommand::Init,
                 payload: vec![0x12, 0x34, 0x56, 0x78, 0x9A, 0xBC, 0xDE, 0xF0],
             }],
         );
@@ -561,7 +644,7 @@ mod test {
             reply,
             Some(vec![Message {
                 cid: CtapHid::CHANNEL_BROADCAST,
-                cmd: CtapHid::COMMAND_INIT,
+                cmd: CtapHidCommand::Init,
                 payload: vec![
                     0x12, // Nonce
                     0x34,
@@ -623,7 +706,7 @@ mod test {
             result,
             vec![Message {
                 cid,
-                cmd: CtapHid::COMMAND_INIT,
+                cmd: CtapHidCommand::Init,
                 payload: vec![
                     0x12, // Nonce
                     0x34,
@@ -660,7 +743,7 @@ mod test {
             &mut ctap_state,
             vec![Message {
                 cid,
-                cmd: CtapHid::COMMAND_PING,
+                cmd: CtapHidCommand::Ping,
                 payload: vec![0x99, 0x99],
             }],
         );
@@ -669,7 +752,7 @@ mod test {
             reply,
             Some(vec![Message {
                 cid,
-                cmd: CtapHid::COMMAND_PING,
+                cmd: CtapHidCommand::Ping,
                 payload: vec![0x99, 0x99]
             }])
         );

src/ctap/hid/receive.rs

@@ -13,7 +13,7 @@
 // limitations under the License.
 
 use super::super::customization::MAX_MSG_SIZE;
-use super::{ChannelID, CtapHid, HidPacket, Message, ProcessedPacket};
+use super::{ChannelID, CtapHid, CtapHidCommand, HidPacket, Message, ProcessedPacket};
 use alloc::vec::Vec;
 use core::mem::swap;
 use libtock_drivers::timer::Timestamp;
@@ -131,7 +131,7 @@ impl MessageAssembler {
                 // Unexpected initialization packet.
                 ProcessedPacket::InitPacket { cmd, len, data } => {
                     self.reset();
-                    if cmd == CtapHid::COMMAND_INIT {
+                    if cmd == CtapHidCommand::Init as u8 {
                         self.parse_init_packet(*cid, cmd, len, data, timestamp)
                     } else {
                         Err((*cid, Error::UnexpectedInit))
@@ -189,7 +189,7 @@ impl MessageAssembler {
             swap(&mut self.payload, &mut payload);
             Some(Message {
                 cid: self.cid,
-                cmd: self.cmd,
+                cmd: CtapHidCommand::from(self.cmd),
                 payload,
             })
         }
@@ -225,12 +225,12 @@ mod test {
         let mut assembler = MessageAssembler::new();
         assert_eq!(
             assembler.parse_packet(
-                &zero_extend(&[0x12, 0x34, 0x56, 0x78, 0x80]),
+                &zero_extend(&[0x12, 0x34, 0x56, 0x78, 0x90]),
                 DUMMY_TIMESTAMP
             ),
             Ok(Some(Message {
                 cid: [0x12, 0x34, 0x56, 0x78],
-                cmd: 0x00,
+                cmd: CtapHidCommand::Cbor,
                 payload: vec![]
             }))
         );
@@ -241,12 +241,12 @@ mod test {
         let mut assembler = MessageAssembler::new();
         assert_eq!(
             assembler.parse_packet(
-                &zero_extend(&[0x12, 0x34, 0x56, 0x78, 0x80, 0x00, 0x10]),
+                &zero_extend(&[0x12, 0x34, 0x56, 0x78, 0x90, 0x00, 0x10]),
                 DUMMY_TIMESTAMP
             ),
             Ok(Some(Message {
                 cid: [0x12, 0x34, 0x56, 0x78],
-                cmd: 0x00,
+                cmd: CtapHidCommand::Cbor,
                 payload: vec![0x00; 0x10]
             }))
         );
@@ -260,12 +260,12 @@ mod test {
         let mut assembler = MessageAssembler::new();
         assert_eq!(
             assembler.parse_packet(
-                &byte_extend(&[0x12, 0x34, 0x56, 0x78, 0x80, 0x00, 0x10], 0xFF),
+                &byte_extend(&[0x12, 0x34, 0x56, 0x78, 0x90, 0x00, 0x10], 0xFF),
                 DUMMY_TIMESTAMP
             ),
             Ok(Some(Message {
                 cid: [0x12, 0x34, 0x56, 0x78],
-                cmd: 0x00,
+                cmd: CtapHidCommand::Cbor,
                 payload: vec![0xFF; 0x10]
             }))
         );
@@ -288,7 +288,7 @@ mod test {
             ),
             Ok(Some(Message {
                 cid: [0x12, 0x34, 0x56, 0x78],
-                cmd: 0x01,
+                cmd: CtapHidCommand::Ping,
                 payload: vec![0x00; 0x40]
             }))
         );
@@ -318,7 +318,7 @@ mod test {
             ),
             Ok(Some(Message {
                 cid: [0x12, 0x34, 0x56, 0x78],
-                cmd: 0x01,
+                cmd: CtapHidCommand::Ping,
                 payload: vec![0x00; 0x80]
             }))
         );
@@ -350,7 +350,7 @@ mod test {
             ),
             Ok(Some(Message {
                 cid: [0x12, 0x34, 0x56, 0x78],
-                cmd: 0x01,
+                cmd: CtapHidCommand::Ping,
                 payload: vec![0x00; 0x1DB9]
             }))
         );
@@ -362,12 +362,15 @@ mod test {
         let mut assembler = MessageAssembler::new();
         for i in 0..10 {
             // Introduce some variability in the messages.
-            let cmd = 2 * i;
+            let cmd = CtapHidCommand::from(i + 1);
             let byte = 3 * i;
 
             assert_eq!(
                 assembler.parse_packet(
-                    &byte_extend(&[0x12, 0x34, 0x56, 0x78, 0x80 | cmd, 0x00, 0x80], byte),
+                    &byte_extend(
+                        &[0x12, 0x34, 0x56, 0x78, 0x80 | cmd as u8, 0x00, 0x80],
+                        byte
+                    ),
                     DUMMY_TIMESTAMP
                 ),
                 Ok(None)
@@ -400,12 +403,12 @@ mod test {
         for i in 0..10 {
             // Introduce some variability in the messages.
             let cid = 0x78 + i;
-            let cmd = 2 * i;
+            let cmd = CtapHidCommand::from(i + 1);
             let byte = 3 * i;
 
             assert_eq!(
                 assembler.parse_packet(
-                    &byte_extend(&[0x12, 0x34, 0x56, cid, 0x80 | cmd, 0x00, 0x80], byte),
+                    &byte_extend(&[0x12, 0x34, 0x56, cid, 0x80 | cmd as u8, 0x00, 0x80], byte),
                     DUMMY_TIMESTAMP
                 ),
                 Ok(None)
@@ -443,11 +446,12 @@ mod test {
         );
 
         // Check that many sorts of packets on another channel are ignored.
-        for cmd in 0..=0xFF {
+        for i in 0..=0xFF {
+            let cmd = CtapHidCommand::from(i);
             for byte in 0..=0xFF {
                 assert_eq!(
                     assembler.parse_packet(
-                        &byte_extend(&[0x12, 0x34, 0x56, 0x9A, cmd, 0x00], byte),
+                        &byte_extend(&[0x12, 0x34, 0x56, 0x9A, cmd as u8, 0x00], byte),
                         DUMMY_TIMESTAMP
                     ),
                     Err(([0x12, 0x34, 0x56, 0x9A], Error::UnexpectedChannel))
@@ -462,7 +466,7 @@ mod test {
             ),
             Ok(Some(Message {
                 cid: [0x12, 0x34, 0x56, 0x78],
-                cmd: 0x01,
+                cmd: CtapHidCommand::Ping,
                 payload: vec![0x00; 0x40]
             }))
         );
@@ -479,12 +483,12 @@ mod test {
             let byte = 2 * i;
             assert_eq!(
                 assembler.parse_packet(
-                    &byte_extend(&[0x12, 0x34, 0x56, 0x78, 0x80, 0x00, 0x10], byte),
+                    &byte_extend(&[0x12, 0x34, 0x56, 0x78, 0x81, 0x00, 0x10], byte),
                     DUMMY_TIMESTAMP
                 ),
                 Ok(Some(Message {
                     cid: [0x12, 0x34, 0x56, 0x78],
-                    cmd: 0x00,
+                    cmd: CtapHidCommand::Ping,
                     payload: vec![byte; 0x10]
                 }))
             );
@@ -584,7 +588,7 @@ mod test {
             assembler.parse_packet(&zero_extend(&[0x12, 0x34, 0x56, 0x78, 0x7F]), timestamp),
             Ok(Some(Message {
                 cid: [0x12, 0x34, 0x56, 0x78],
-                cmd: 0x01,
+                cmd: CtapHidCommand::Ping,
                 payload: vec![0x00; 0x1DB9]
             }))
         );
@@ -612,7 +616,7 @@ mod test {
             ),
             Ok(Some(Message {
                 cid: [0x12, 0x34, 0x56, 0x78],
-                cmd: 0x06,
+                cmd: CtapHidCommand::Init,
                 payload: vec![0x12, 0x34, 0x56, 0x78, 0x9A, 0xBC, 0xDE, 0xF0]
             }))
         );

src/ctap/hid/send.rs

@@ -14,6 +14,9 @@
 
 use super::{CtapHid, HidPacket, Message};
 
+/// Iterator for HID packets.
+///
+/// The `new` constructor splits the CTAP `Message` into `HidPacket`s for sending over USB.
 pub struct HidPacketIterator(Option<MessageSplitter>);
 
 impl HidPacketIterator {
@@ -99,7 +102,7 @@ impl Iterator for MessageSplitter {
         match self.seq {
             None => {
                 // First, send an initialization packet.
-                self.packet[4] = self.message.cmd | CtapHid::TYPE_INIT_BIT;
+                self.packet[4] = self.message.cmd as u8 | CtapHid::TYPE_INIT_BIT;
                 self.packet[5] = (payload_len >> 8) as u8;
                 self.packet[6] = payload_len as u8;
 
@@ -128,6 +131,7 @@ impl Iterator for MessageSplitter {
 
 #[cfg(test)]
 mod test {
+    use super::super::CtapHidCommand;
     use super::*;
 
     fn assert_packet_output_equality(message: Message, expected_packets: Vec<HidPacket>) {
@@ -142,11 +146,11 @@ mod test {
     fn test_hid_packet_iterator_single_packet() {
         let message = Message {
             cid: [0x12, 0x34, 0x56, 0x78],
-            cmd: 0x4C,
+            cmd: CtapHidCommand::Cbor,
             payload: vec![0xAA, 0xBB],
         };
         let expected_packets: Vec<HidPacket> = vec![[
-            0x12, 0x34, 0x56, 0x78, 0xCC, 0x00, 0x02, 0xAA, 0xBB, 0x00, 0x00, 0x00, 0x00, 0x00,
+            0x12, 0x34, 0x56, 0x78, 0x90, 0x00, 0x02, 0xAA, 0xBB, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
@@ -159,11 +163,11 @@ mod test {
     fn test_hid_packet_iterator_big_single_packet() {
         let message = Message {
             cid: [0x12, 0x34, 0x56, 0x78],
-            cmd: 0x4C,
+            cmd: CtapHidCommand::Cbor,
             payload: vec![0xAA; 64 - 7],
         };
         let expected_packets: Vec<HidPacket> = vec![[
-            0x12, 0x34, 0x56, 0x78, 0xCC, 0x00, 0x39, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA,
+            0x12, 0x34, 0x56, 0x78, 0x90, 0x00, 0x39, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA,
             0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA,
             0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA,
             0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA,
@@ -176,12 +180,12 @@ mod test {
     fn test_hid_packet_iterator_two_packets() {
         let message = Message {
             cid: [0x12, 0x34, 0x56, 0x78],
-            cmd: 0x4C,
+            cmd: CtapHidCommand::Cbor,
             payload: vec![0xAA; 64 - 7 + 1],
         };
         let expected_packets: Vec<HidPacket> = vec![
             [
-                0x12, 0x34, 0x56, 0x78, 0xCC, 0x00, 0x3A, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA,
+                0x12, 0x34, 0x56, 0x78, 0x90, 0x00, 0x3A, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA,
                 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA,
                 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA,
                 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA,
@@ -204,12 +208,12 @@ mod test {
         payload.extend(vec![0xBB; 64 - 5]);
         let message = Message {
             cid: [0x12, 0x34, 0x56, 0x78],
-            cmd: 0x4C,
+            cmd: CtapHidCommand::Cbor,
             payload,
         };
         let expected_packets: Vec<HidPacket> = vec![
             [
-                0x12, 0x34, 0x56, 0x78, 0xCC, 0x00, 0x74, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA,
+                0x12, 0x34, 0x56, 0x78, 0x90, 0x00, 0x74, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA,
                 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA,
                 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA,
                 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA,
@@ -238,12 +242,12 @@ mod test {
 
         let message = Message {
             cid: [0x12, 0x34, 0x56, 0x78],
-            cmd: 0xAB,
+            cmd: CtapHidCommand::Msg,
             payload,
         };
 
         let mut expected_packets: Vec<HidPacket> = vec![[
-            0x12, 0x34, 0x56, 0x78, 0xAB, 0x1D, 0xB9, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+            0x12, 0x34, 0x56, 0x78, 0x83, 0x1D, 0xB9, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
             0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
             0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
             0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
@@ -271,7 +275,7 @@ mod test {
         assert_eq!(payload.len(), 0x1dba);
         let message = Message {
             cid: [0x12, 0x34, 0x56, 0x78],
-            cmd: 0xAB,
+            cmd: CtapHidCommand::Msg,
             payload,
         };
         assert!(HidPacketIterator::new(message).is_none());
@@ -283,7 +287,7 @@ mod test {
         let payload = vec![0xFF; 0x10000];
         let message = Message {
             cid: [0x12, 0x34, 0x56, 0x78],
-            cmd: 0xAB,
+            cmd: CtapHidCommand::Msg,
             payload,
         };
         assert!(HidPacketIterator::new(message).is_none());

src/env/tock/mod.rs

@@ -1,5 +1,5 @@
 use self::storage::{SyscallStorage, SyscallUpgradeStorage};
-use crate::ctap::hid::{ChannelID, CtapHid, KeepaliveStatus, ProcessedPacket};
+use crate::ctap::hid::{ChannelID, CtapHid, CtapHidCommand, KeepaliveStatus, ProcessedPacket};
 use crate::ctap::status_code::Ctap2StatusCode;
 use crate::env::{Env, UserPresence};
 use core::cell::Cell;
@@ -121,7 +121,7 @@ fn send_keepalive_up_needed(
                 }
                 match processed_packet {
                     ProcessedPacket::InitPacket { cmd, .. } => {
-                        if cmd == CtapHid::COMMAND_CANCEL {
+                        if cmd == CtapHidCommand::Cancel as u8 {
                             // 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();