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authorRobin Krahl <robin.krahl@ireas.org>2019-02-19 22:09:04 +0000
committerRobin Krahl <robin.krahl@ireas.org>2019-02-19 23:24:50 +0100
commit1e127de5173e3b8fb62efc79f97651ca22694441 (patch)
tree968e3746893d764341d7902beb5656c37a7f8ddd
parentdbae67d6fbb1f8a310b8de820fcda34c31eed39f (diff)
downloadntw-1e127de5173e3b8fb62efc79f97651ca22694441.tar.gz
ntw-1e127de5173e3b8fb62efc79f97651ca22694441.tar.bz2
Validate CRC of incoming data
The data sent with Set_Report requests contains a CRC which we so far ignored. This patch adds a Crc struct that uses the CRC peripheral to calculate the CRC for some data and uses it to validate the CRC of the received data.
-rw-r--r--src/crc.rs40
-rw-r--r--src/device.rs16
-rw-r--r--src/main.rs7
3 files changed, 59 insertions, 4 deletions
diff --git a/src/crc.rs b/src/crc.rs
new file mode 100644
index 0000000..cfcf982
--- /dev/null
+++ b/src/crc.rs
@@ -0,0 +1,40 @@
+// Copyright 2019 Robin Krahl <robin.krahl@ireas.org>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+use hal::stm32::CRC;
+
+pub struct Crc {
+ crc: CRC,
+}
+
+impl Crc {
+ pub fn new(crc: CRC) -> Self {
+ Crc { crc }
+ }
+
+ pub fn get(&self, data: &[u8]) -> u32 {
+ self.reset();
+ data.chunks(4)
+ .map(slice_to_u32)
+ .for_each(|val| self.write(val));
+ self.read()
+ }
+
+ fn write(&self, val: u32) {
+ self.crc.dr.write(|w| w.dr().bits(val));
+ }
+
+ fn read(&self) -> u32 {
+ self.crc.dr.read().dr().bits()
+ }
+
+ fn reset(&self) {
+ self.crc.cr.write(|w| w.reset().reset());
+ }
+}
+
+fn slice_to_u32(data: &[u8]) -> u32 {
+ data.iter()
+ .enumerate()
+ .fold(0, |acc, (idx, val)| acc + (u32::from(*val) << (idx * 8)))
+}
diff --git a/src/device.rs b/src/device.rs
index 0df14ae..fc119d5 100644
--- a/src/device.rs
+++ b/src/device.rs
@@ -7,6 +7,7 @@ use usb_device::bus::{UsbBus, UsbBusAllocator};
use usb_device::device::{UsbDevice, UsbDeviceBuilder, UsbVidPid};
use crate::commands::{CommandId, COMMAND_LEN};
+use crate::crc::Crc;
use crate::hid::{HidDevice, Protocol, ReportType, Subclass};
use crate::util::TryFrom;
@@ -85,14 +86,18 @@ impl Response {
}
pub struct Nitrokey {
+ crc: Crc,
request: Option<Request>,
+ request_crc: u32,
buf: [u8; REPORT_LEN],
}
impl Nitrokey {
- pub fn new() -> Self {
+ pub fn new(crc: Crc) -> Self {
Nitrokey {
+ crc,
request: None,
+ request_crc: 0,
buf: [0; REPORT_LEN],
}
}
@@ -118,12 +123,15 @@ impl HidDevice for Nitrokey {
if let Some(ref request) = self.request {
let mut response = Response::new(DeviceStatus::Ok, request.command_id, request.crc);
- response.command_status =
+ response.command_status = if self.request_crc == request.crc {
if let Ok(command_id) = CommandId::try_from(request.command_id) {
command_id.execute(&request.data, &mut response.data)
} else {
CommandStatus::UnknownCommand
- };
+ }
+ } else {
+ CommandStatus::WrongCrc
+ };
// TODO: calculate actual CRC
response.crc = 1; // libnitrokey accepts any non-zero value
@@ -146,6 +154,8 @@ impl HidDevice for Nitrokey {
} else {
let (request, len) = ssmarshal::deserialize(data).map_err(|_| ())?;
assert!(len == REPORT_LEN);
+ // the last four bytes are ignored as they contain the CRC
+ self.request_crc = self.crc.get(&data[..REPORT_LEN - 4]);
self.request = Some(request);
Ok(())
}
diff --git a/src/main.rs b/src/main.rs
index caf7fdf..7e364ab 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -10,6 +10,7 @@ extern crate panic_halt;
mod util;
mod commands;
+mod crc;
mod device;
mod hid;
@@ -18,6 +19,7 @@ use hal::prelude::*;
use stm32f103xx_usb::UsbBus;
use usb_device::class::UsbClass;
+use crate::crc::Crc;
use crate::device::Nitrokey;
use crate::hid::HidClass;
@@ -25,6 +27,9 @@ use crate::hid::HidClass;
fn main() -> ! {
let p = hal::stm32::Peripherals::take().unwrap();
+ p.RCC.ahbenr.modify(|_, w| w.crcen().set_bit());
+ let crc = Crc::new(p.CRC);
+
let mut flash = p.FLASH.constrain();
let mut rcc = p.RCC.constrain();
@@ -40,7 +45,7 @@ fn main() -> ! {
let mut gpioa = p.GPIOA.split(&mut rcc.apb2);
let usb_bus = UsbBus::usb_with_reset(p.USB, &mut rcc.apb1, &clocks, &mut gpioa.crh, gpioa.pa12);
- let mut usb_class = HidClass::new(Nitrokey::new(), &usb_bus);
+ let mut usb_class = HidClass::new(Nitrokey::new(crc), &usb_bus);
let mut usb_dev = device::create_usb_device(&usb_bus);
usb_dev.force_reset().expect("USB reset failed");