From 124d334166848a729229dc1f3bf96ebdcecd4cb2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sosth=C3=A8ne=20Gu=C3=A9don?= <sosthene@nitrokey.com>
Date: Thu, 10 Nov 2022 15:28:57 +0100
Subject: [PATCH] Check that command algorithm corresponds with state

---
 src/commands.rs  |  2 +-
 src/container.rs | 11 +++++++++++
 src/lib.rs       | 26 ++++++++++++++------------
 3 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/src/commands.rs b/src/commands.rs
index 7aa0bdd..0b8cdde 100644
--- a/src/commands.rs
+++ b/src/commands.rs
@@ -66,7 +66,7 @@ pub enum Command<'l> {
 
 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
 pub struct GeneralAuthenticate {
-    algorithm: piv_types::Algorithms,
+    pub algorithm: piv_types::Algorithms,
     key_reference: AuthenticateKeyReference,
 }
 
diff --git a/src/container.rs b/src/container.rs
index 8f43553..7206a96 100644
--- a/src/container.rs
+++ b/src/container.rs
@@ -45,6 +45,17 @@ macro_rules! enum_subset {
             }
         }
 
+        impl PartialEq<$sup> for $name {
+            fn eq(&self, other: &$sup) -> bool {
+                match (self,other) {
+                    $(
+                        | ($name::$var, $sup::$var)
+                    )* => true,
+                    _ => false
+                }
+            }
+        }
+
         impl TryFrom<u8> for $name {
             type Error = ::iso7816::Status;
             fn try_from(tag: u8) -> ::core::result::Result<Self, Self::Error> {
diff --git a/src/lib.rs b/src/lib.rs
index 88f54ae..e1a3e88 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -474,7 +474,7 @@ impl<'a, T: trussed::Client + trussed::client::Ed255> LoadedAuthenticator<'a, T>
 
     pub fn request_for_response<const R: usize>(
         &mut self,
-        _auth: GeneralAuthenticate,
+        auth: GeneralAuthenticate,
         data: derp::Input<'_>,
         _reply: &mut Data<R>,
     ) -> Result {
@@ -484,6 +484,11 @@ impl<'a, T: trussed::Client + trussed::client::Ed255> LoadedAuthenticator<'a, T>
             warn!("Bad response length");
             return Err(Status::IncorrectDataParameter);
         }
+        if alg != auth.algorithm {
+            warn!("Bad algorithm");
+            return Err(Status::IncorrectP1OrP2Parameter);
+        }
+
         let Some(CommandCache::AuthenticateChallenge(plaintext)) = self.state.runtime.command_cache.take() else {
             warn!("Request for response without cached challenge");
             return Err(Status::ConditionsOfUseNotSatisfied);
@@ -518,24 +523,21 @@ impl<'a, T: trussed::Client + trussed::client::Ed255> LoadedAuthenticator<'a, T>
 
     pub fn request_for_challenge<const R: usize>(
         &mut self,
-        _auth: GeneralAuthenticate,
+        auth: GeneralAuthenticate,
         data: derp::Input<'_>,
         reply: &mut Data<R>,
     ) -> Result {
-        if data.len() != 0 {
+        let alg = self.state.persistent.keys.management_key.alg;
+        if !data.is_empty() {
             warn!("Request for challenge with non empty data");
             return Err(Status::IncorrectDataParameter);
         }
+        if alg != auth.algorithm {
+            warn!("Bad algorithm");
+            return Err(Status::IncorrectP1OrP2Parameter);
+        }
         info!("Request for challenge ");
-        let challenge = syscall!(self.trussed.random_bytes(
-            self.state
-                .persistent
-                .keys
-                .management_key
-                .alg
-                .challenge_length()
-        ))
-        .bytes;
+        let challenge = syscall!(self.trussed.random_bytes(alg.challenge_length())).bytes;
         self.state.runtime.command_cache = Some(CommandCache::AuthenticateChallenge(
             Bytes::from_slice(&challenge).unwrap(),
         ));