Add Unix Peer Credential auth support

This commit adds support for authentication using Unix Peer Credentials.
This involves the library automatically populating the `Auth` field of
every request with a serialized version of the UID.

Signed-off-by: Ionut Mihalcea <ionut.mihalcea@arm.com>

Author: ionut-arm

src/auth.rs

@@ -15,6 +15,8 @@ pub enum AuthenticationData {
     /// The `Secret` struct can be imported from
     /// `parsec_client::core::secrecy::Secret`.
     AppIdentity(Secret<String>),
+    /// Used for authentication via
+    UnixPeerCredentials,
 }
 
 impl AuthenticationData {
@@ -23,6 +25,7 @@ impl AuthenticationData {
         match self {
             AuthenticationData::None => AuthType::NoAuth,
             AuthenticationData::AppIdentity(_) => AuthType::Direct,
+            AuthenticationData::UnixPeerCredentials => AuthType::UnixPeerCredentials,
         }
     }
 }
@@ -34,6 +37,10 @@ impl From<&AuthenticationData> for RequestAuth {
             AuthenticationData::AppIdentity(name) => {
                 RequestAuth::new(name.expose_secret().bytes().collect())
             }
+            AuthenticationData::UnixPeerCredentials => {
+                let current_uid = users::get_current_uid();
+                RequestAuth::new(current_uid.to_le_bytes().to_vec())
+            }
         }
     }
 }

src/core/testing/core_tests.rs

@@ -774,6 +774,25 @@ fn auth_value_test() {
     );
 }
 
+#[test]
+fn peer_credential_auth_test() {
+    let mut client: TestBasicClient = Default::default();
+    client.set_auth_data(AuthenticationData::UnixPeerCredentials);
+    client.set_mock_read(&get_response_bytes_from_result(
+        NativeResult::PsaDestroyKey(operations::psa_destroy_key::Result {}),
+    ));
+    let key_name = String::from("key-name");
+    client
+        .psa_destroy_key(key_name)
+        .expect("Failed to call destroy key");
+
+    let req = get_req_from_bytes(client.get_mock_write());
+    assert_eq!(
+        &users::get_current_uid().to_le_bytes().to_vec(),
+        req.auth.buffer.expose_secret()
+    );
+}
+
 #[test]
 fn failing_ipc_test() {
     let mut client: TestBasicClient = Default::default();