vm_payload/src/api.rs - android_packages_modules_Virtualization - Gitiles

 // Copyright 2022, The Android Open Source Project
 //
 // 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.

 //! This module handles the interaction with virtual machine payload service.

 use android_system_virtualization_payload::aidl::android::system::virtualization::payload:: IVmPayloadService::{
     IVmPayloadService, ENCRYPTEDSTORE_MOUNTPOINT, VM_APK_CONTENTS_PATH,
     VM_PAYLOAD_SERVICE_SOCKET_NAME, AttestationResult::AttestationResult,
 };
 use anyhow::{bail, ensure, Context, Result};
 use binder::{
     unstable_api::{new_spibinder, AIBinder},
     Strong,
 };
 use lazy_static::lazy_static;
 use log::{error, info, Level};
 use rpcbinder::{RpcServer, RpcSession};
 use openssl::{ec::EcKey, sha::sha256, ecdsa::EcdsaSig};
 use std::convert::Infallible;
 use std::ffi::{CString, CStr};
 use std::fmt::Debug;
 use std::os::raw::{c_char, c_void};
 use std::path::Path;
 use std::ptr::{self, NonNull};
 use std::sync::{
     atomic::{AtomicBool, Ordering},
     Mutex,
 };
 use vm_payload_status_bindgen::attestation_status_t;

 lazy_static! {
     static ref VM_APK_CONTENTS_PATH_C: CString =
         CString::new(VM_APK_CONTENTS_PATH).expect("CString::new failed");
     static ref PAYLOAD_CONNECTION: Mutex<Option<Strong<dyn IVmPayloadService>>> = Mutex::default();
     static ref VM_ENCRYPTED_STORAGE_PATH_C: CString =
         CString::new(ENCRYPTEDSTORE_MOUNTPOINT).expect("CString::new failed");
 }

 static ALREADY_NOTIFIED: AtomicBool = AtomicBool::new(false);

 /// Return a connection to the payload service in Microdroid Manager. Uses the existing connection
 /// if there is one, otherwise attempts to create a new one.
 fn get_vm_payload_service() -> Result<Strong<dyn IVmPayloadService>> {
     let mut connection = PAYLOAD_CONNECTION.lock().unwrap();
     if let Some(strong) = &*connection {
         Ok(strong.clone())
     } else {
         let new_connection: Strong<dyn IVmPayloadService> = RpcSession::new()
             .setup_unix_domain_client(VM_PAYLOAD_SERVICE_SOCKET_NAME)
             .context(format!("Failed to connect to service: {}", VM_PAYLOAD_SERVICE_SOCKET_NAME))?;
         *connection = Some(new_connection.clone());
         Ok(new_connection)
     }
 }

 /// Make sure our logging goes to logcat. It is harmless to call this more than once.
 fn initialize_logging() {
     android_logger::init_once(
         android_logger::Config::default().with_tag("vm_payload").with_min_level(Level::Info),
     );
 }

 /// In many cases clients can't do anything useful if API calls fail, and the failure
 /// generally indicates that the VM is exiting or otherwise doomed. So rather than
 /// returning a non-actionable error indication we just log the problem and abort
 /// the process.
 fn unwrap_or_abort<T, E: Debug>(result: Result<T, E>) -> T {
     result.unwrap_or_else(|e| {
         let msg = format!("{:?}", e);
         error!("{msg}");
         panic!("{msg}")
     })
 }

 /// Notifies the host that the payload is ready.
 /// Panics on failure.
 #[no_mangle]
 pub extern "C" fn AVmPayload_notifyPayloadReady() {
     initialize_logging();

     if !ALREADY_NOTIFIED.swap(true, Ordering::Relaxed) {
         unwrap_or_abort(try_notify_payload_ready());

         info!("Notified host payload ready successfully");
     }
 }

 /// Notifies the host that the payload is ready.
 /// Returns a `Result` containing error information if failed.
 fn try_notify_payload_ready() -> Result<()> {
     get_vm_payload_service()?.notifyPayloadReady().context("Cannot notify payload ready")
 }

 /// Runs a binder RPC server, serving the supplied binder service implementation on the given vsock
 /// port.
 ///
 /// If and when the server is ready for connections (it is listening on the port), `on_ready` is
 /// called to allow appropriate action to be taken - e.g. to notify clients that they may now
 /// attempt to connect.
 ///
 /// The current thread joins the binder thread pool to handle incoming messages.
 /// This function never returns.
 ///
 /// Panics on error (including unexpected server exit).
 ///
 /// # Safety
 ///
 /// If present, the `on_ready` callback must be a valid function pointer, which will be called at
 /// most once, while this function is executing, with the `param` parameter.
 #[no_mangle]
 pub unsafe extern "C" fn AVmPayload_runVsockRpcServer(
     service: *mut AIBinder,
     port: u32,
     on_ready: Option<unsafe extern "C" fn(param: *mut c_void)>,
     param: *mut c_void,
 ) -> Infallible {
     initialize_logging();

     // SAFETY: try_run_vsock_server has the same requirements as this function
     unwrap_or_abort(unsafe { try_run_vsock_server(service, port, on_ready, param) })
 }

 /// # Safety: Same as `AVmPayload_runVsockRpcServer`.
 unsafe fn try_run_vsock_server(
     service: *mut AIBinder,
     port: u32,
     on_ready: Option<unsafe extern "C" fn(param: *mut c_void)>,
     param: *mut c_void,
 ) -> Result<Infallible> {
     // SAFETY: AIBinder returned has correct reference count, and the ownership can
     // safely be taken by new_spibinder.
     let service = unsafe { new_spibinder(service) };
     if let Some(service) = service {
         match RpcServer::new_vsock(service, libc::VMADDR_CID_HOST, port) {
             Ok(server) => {
                 if let Some(on_ready) = on_ready {
                     // SAFETY: We're calling the callback with the parameter specified within the
                     // allowed lifetime.
                     unsafe { on_ready(param) };
                 }
                 server.join();
                 bail!("RpcServer unexpectedly terminated");
             }
             Err(err) => {
                 bail!("Failed to start RpcServer: {:?}", err);
             }
         }
     } else {
         bail!("Failed to convert the given service from AIBinder to SpIBinder.");
     }
 }

 /// Get a secret that is uniquely bound to this VM instance.
 /// Panics on failure.
 ///
 /// # Safety
 ///
 /// Behavior is undefined if any of the following conditions are violated:
 ///
 /// * `identifier` must be [valid] for reads of `identifier_size` bytes.
 /// * `secret` must be [valid] for writes of `size` bytes.
 ///
 /// [valid]: ptr#safety
 #[no_mangle]
 pub unsafe extern "C" fn AVmPayload_getVmInstanceSecret(
     identifier: *const u8,
     identifier_size: usize,
     secret: *mut u8,
     size: usize,
 ) {
     initialize_logging();

     // SAFETY: See the requirements on `identifier` above.
     let identifier = unsafe { std::slice::from_raw_parts(identifier, identifier_size) };
     let vm_secret = unwrap_or_abort(try_get_vm_instance_secret(identifier, size));

     // SAFETY: See the requirements on `secret` above; `vm_secret` is known to have length `size`,
     // and cannot overlap `secret` because we just allocated it.
     unsafe {
         ptr::copy_nonoverlapping(vm_secret.as_ptr(), secret, size);
     }
 }

 fn try_get_vm_instance_secret(identifier: &[u8], size: usize) -> Result<Vec<u8>> {
     let vm_secret = get_vm_payload_service()?
         .getVmInstanceSecret(identifier, i32::try_from(size)?)
         .context("Cannot get VM instance secret")?;
     ensure!(
         vm_secret.len() == size,
         "Returned secret has {} bytes, expected {}",
         vm_secret.len(),
         size
     );
     Ok(vm_secret)
 }

 /// Get the VM's attestation chain.
 /// Panics on failure.
 ///
 /// # Safety
 ///
 /// Behavior is undefined if any of the following conditions are violated:
 ///
 /// * `data` must be [valid] for writes of `size` bytes, if size > 0.
 ///
 /// [valid]: ptr#safety
 #[no_mangle]
 pub unsafe extern "C" fn AVmPayload_getDiceAttestationChain(data: *mut u8, size: usize) -> usize {
     initialize_logging();

     let chain = unwrap_or_abort(try_get_dice_attestation_chain());
     if size != 0 {
         // SAFETY: See the requirements on `data` above. The number of bytes copied doesn't exceed
         // the length of either buffer, and `chain` cannot overlap `data` because we just allocated
         // it. We allow data to be null, which is never valid, but only if size == 0 which is
         // checked above.
         unsafe { ptr::copy_nonoverlapping(chain.as_ptr(), data, std::cmp::min(chain.len(), size)) };
     }
     chain.len()
 }

 fn try_get_dice_attestation_chain() -> Result<Vec<u8>> {
     get_vm_payload_service()?.getDiceAttestationChain().context("Cannot get attestation chain")
 }

 /// Get the VM's attestation CDI.
 /// Panics on failure.
 ///
 /// # Safety
 ///
 /// Behavior is undefined if any of the following conditions are violated:
 ///
 /// * `data` must be [valid] for writes of `size` bytes, if size > 0.
 ///
 /// [valid]: ptr#safety
 #[no_mangle]
 pub unsafe extern "C" fn AVmPayload_getDiceAttestationCdi(data: *mut u8, size: usize) -> usize {
     initialize_logging();

     let cdi = unwrap_or_abort(try_get_dice_attestation_cdi());
     if size != 0 {
         // SAFETY: See the requirements on `data` above. The number of bytes copied doesn't exceed
         // the length of either buffer, and `cdi` cannot overlap `data` because we just allocated
         // it. We allow data to be null, which is never valid, but only if size == 0 which is
         // checked above.
         unsafe { ptr::copy_nonoverlapping(cdi.as_ptr(), data, std::cmp::min(cdi.len(), size)) };
     }
     cdi.len()
 }

 fn try_get_dice_attestation_cdi() -> Result<Vec<u8>> {
     get_vm_payload_service()?.getDiceAttestationCdi().context("Cannot get attestation CDI")
 }

 /// Requests the remote attestation of the client VM.
 ///
 /// The challenge will be included in the certificate chain in the attestation result,
 /// serving as proof of the freshness of the result.
 ///
 /// # Safety
 ///
 /// Behavior is undefined if any of the following conditions are violated:
 ///
 /// * `challenge` must be [valid] for reads of `challenge_size` bytes.
 /// * `res` must be [valid] to write the attestation result.
 /// * The region of memory beginning at `challenge` with `challenge_size` bytes must not
 ///  overlap with the region of memory `res` points to.
 ///
 /// [valid]: ptr#safety
 #[no_mangle]
 pub unsafe extern "C" fn AVmPayload_requestAttestation(
     challenge: *const u8,
     challenge_size: usize,
     res: &mut *mut AttestationResult,
 ) -> attestation_status_t {
     initialize_logging();
     const MAX_CHALLENGE_SIZE: usize = 64;
     if challenge_size > MAX_CHALLENGE_SIZE {
         return attestation_status_t::ATTESTATION_ERROR_INVALID_CHALLENGE;
     }
     let challenge = if challenge_size == 0 {
         &[]
     } else {
         // SAFETY: The caller guarantees that `challenge` is valid for reads of
         // `challenge_size` bytes and `challenge_size` is not zero.
         unsafe { std::slice::from_raw_parts(challenge, challenge_size) }
     };
     let attestation_res = unwrap_or_abort(try_request_attestation(challenge));
     *res = Box::into_raw(Box::new(attestation_res));
     attestation_status_t::ATTESTATION_OK
 }

 fn try_request_attestation(public_key: &[u8]) -> Result<AttestationResult> {
     get_vm_payload_service()?
         .requestAttestation(public_key)
         .context("Failed to request attestation")
 }

 /// Converts the return value from `AVmPayload_requestAttestation` to a text string
 /// representing the error code.
 #[no_mangle]
 pub extern "C" fn AVmAttestationResult_resultToString(
     status: attestation_status_t,
 ) -> *const c_char {
     let message = match status {
         attestation_status_t::ATTESTATION_OK => {
             CStr::from_bytes_with_nul(b"The remote attestation completes successfully.\0").unwrap()
         }
         attestation_status_t::ATTESTATION_ERROR_INVALID_CHALLENGE => {
             CStr::from_bytes_with_nul(b"The challenge size is not between 0 and 64.\0").unwrap()
         }
         _ => CStr::from_bytes_with_nul(
             b"The remote attestation has failed due to an unspecified cause.\0",
         )
         .unwrap(),
     };
     message.as_ptr()
 }

 /// Reads the DER-encoded ECPrivateKey structure specified in [RFC 5915 s3] for the
 /// EC P-256 private key from the provided attestation result.
 ///
 /// # Safety
 ///
 /// Behavior is undefined if any of the following conditions are violated:
 ///
 /// * `data` must be [valid] for writes of `size` bytes, if size > 0.
 /// * The region of memory beginning at `data` with `size` bytes must not overlap with the
 ///  region of memory `res` points to.
 ///
 /// [valid]: ptr#safety
 /// [RFC 5915 s3]: https://datatracker.ietf.org/doc/html/rfc5915#section-3
 #[no_mangle]
 pub unsafe extern "C" fn AVmAttestationResult_getPrivateKey(
     res: &AttestationResult,
     data: *mut u8,
     size: usize,
 ) -> usize {
     let private_key = &res.privateKey;
     if size != 0 {
         let data = NonNull::new(data).expect("data must not be null when size > 0");
         // SAFETY: See the requirements on `data` above. The number of bytes copied doesn't exceed
         // the length of either buffer, and the caller ensures that `private_key` cannot overlap
         // `data`. We allow data to be null, which is never valid, but only if size == 0
         // which is checked above.
         unsafe {
             ptr::copy_nonoverlapping(
                 private_key.as_ptr(),
                 data.as_ptr(),
                 std::cmp::min(private_key.len(), size),
             )
         };
     }
     private_key.len()
 }

 /// Signs the given message using ECDSA P-256, the message is first hashed with SHA-256 and
 /// then it is signed with the attested EC P-256 private key in the attestation result.
 ///
 /// # Safety
 ///
 /// Behavior is undefined if any of the following conditions are violated:
 ///
 /// * `message` must be [valid] for reads of `message_size` bytes.
 /// * `data` must be [valid] for writes of `size` bytes, if size > 0.
 /// * The region of memory beginning at `data` with `size` bytes must not overlap with the
 ///  region of memory `res` or `message` point to.
 ///
 ///
 /// [valid]: ptr#safety
 #[no_mangle]
 pub unsafe extern "C" fn AVmAttestationResult_sign(
     res: &AttestationResult,
     message: *const u8,
     message_size: usize,
     data: *mut u8,
     size: usize,
 ) -> usize {
     if message_size == 0 {
         panic!("Message to be signed must not be empty.")
     }
     // SAFETY: See the requirements on `message` above.
     let message = unsafe { std::slice::from_raw_parts(message, message_size) };
     let signature = unwrap_or_abort(try_ecdsa_sign(message, &res.privateKey));
     if size != 0 {
         let data = NonNull::new(data).expect("data must not be null when size > 0");
         // SAFETY: See the requirements on `data` above. The number of bytes copied doesn't exceed
         // the length of either buffer, and the caller ensures that `signature` cannot overlap
         // `data`. We allow data to be null, which is never valid, but only if size == 0
         // which is checked above.
         unsafe {
             ptr::copy_nonoverlapping(
                 signature.as_ptr(),
                 data.as_ptr(),
                 std::cmp::min(signature.len(), size),
             )
         };
     }
     signature.len()
 }

 fn try_ecdsa_sign(message: &[u8], der_encoded_ec_private_key: &[u8]) -> Result<Vec<u8>> {
     let private_key = EcKey::private_key_from_der(der_encoded_ec_private_key)?;
     let digest = sha256(message);
     let sig = EcdsaSig::sign(&digest, &private_key)?;
     Ok(sig.to_der()?)
 }

 /// Gets the number of certificates in the certificate chain.
 #[no_mangle]
 pub extern "C" fn AVmAttestationResult_getCertificateCount(res: &AttestationResult) -> usize {
     res.certificateChain.len()
 }

 /// Retrieves the certificate at the given `index` from the certificate chain in the provided
 /// attestation result.
 ///
 /// # Safety
 ///
 /// Behavior is undefined if any of the following conditions are violated:
 ///
 /// * `data` must be [valid] for writes of `size` bytes, if size > 0.
 /// * `index` must be within the range of [0, number of certificates). The number of certificates
 ///   can be obtained with `AVmAttestationResult_getCertificateCount`.
 /// * The region of memory beginning at `data` with `size` bytes must not overlap with the
 ///  region of memory `res` points to.
 ///
 /// [valid]: ptr#safety
 #[no_mangle]
 pub unsafe extern "C" fn AVmAttestationResult_getCertificateAt(
     res: &AttestationResult,
     index: usize,
     data: *mut u8,
     size: usize,
 ) -> usize {
     let certificate =
         &res.certificateChain.get(index).expect("The index is out of bounds.").encodedCertificate;
     if size != 0 {
         let data = NonNull::new(data).expect("data must not be null when size > 0");
         // SAFETY: See the requirements on `data` above. The number of bytes copied doesn't exceed
         // the length of either buffer, and the caller ensures that `certificate` cannot overlap
         // `data`. We allow data to be null, which is never valid, but only if size == 0
         // which is checked above.
         unsafe {
             ptr::copy_nonoverlapping(
                 certificate.as_ptr(),
                 data.as_ptr(),
                 std::cmp::min(certificate.len(), size),
             )
         };
     }
     certificate.len()
 }

 /// Frees all the data owned by given attestation result and result itself.
 ///
 /// # Safety
 ///
 /// Behavior is undefined if any of the following conditions are violated:
 ///
 /// * `res` must point to a valid `AttestationResult` and has not been freed before.
 #[no_mangle]
 pub unsafe extern "C" fn AVmAttestationResult_free(res: *mut AttestationResult) {
     if !res.is_null() {
         // SAFETY: The result is only freed once is ensured by the caller.
         let res = unsafe { Box::from_raw(res) };
         drop(res)
     }
 }

 /// Gets the path to the APK contents.
 #[no_mangle]
 pub extern "C" fn AVmPayload_getApkContentsPath() -> *const c_char {
     VM_APK_CONTENTS_PATH_C.as_ptr()
 }

 /// Gets the path to the VM's encrypted storage.
 #[no_mangle]
 pub extern "C" fn AVmPayload_getEncryptedStoragePath() -> *const c_char {
     if Path::new(ENCRYPTEDSTORE_MOUNTPOINT).exists() {
         VM_ENCRYPTED_STORAGE_PATH_C.as_ptr()
     } else {
         ptr::null()
     }
 }
	// Copyright 2022, The Android Open Source Project
	//
	// 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.

	//! This module handles the interaction with virtual machine payload service.

	use android_system_virtualization_payload::aidl::android::system::virtualization::payload:: IVmPayloadService::{
	IVmPayloadService, ENCRYPTEDSTORE_MOUNTPOINT, VM_APK_CONTENTS_PATH,
	VM_PAYLOAD_SERVICE_SOCKET_NAME, AttestationResult::AttestationResult,
	};
	use anyhow::{bail, ensure, Context, Result};
	use binder::{
	unstable_api::{new_spibinder, AIBinder},
	Strong,
	};
	use lazy_static::lazy_static;
	use log::{error, info, Level};
	use rpcbinder::{RpcServer, RpcSession};
	use openssl::{ec::EcKey, sha::sha256, ecdsa::EcdsaSig};
	use std::convert::Infallible;
	use std::ffi::{CString, CStr};
	use std::fmt::Debug;
	use std::os::raw::{c_char, c_void};
	use std::path::Path;
	use std::ptr::{self, NonNull};
	use std::sync::{
	atomic::{AtomicBool, Ordering},
	Mutex,
	};
	use vm_payload_status_bindgen::attestation_status_t;

	lazy_static! {
	static ref VM_APK_CONTENTS_PATH_C: CString =
	CString::new(VM_APK_CONTENTS_PATH).expect("CString::new failed");
	static ref PAYLOAD_CONNECTION: Mutex<Option<Strong<dyn IVmPayloadService>>> = Mutex::default();
	static ref VM_ENCRYPTED_STORAGE_PATH_C: CString =
	CString::new(ENCRYPTEDSTORE_MOUNTPOINT).expect("CString::new failed");
	}

	static ALREADY_NOTIFIED: AtomicBool = AtomicBool::new(false);

	/// Return a connection to the payload service in Microdroid Manager. Uses the existing connection
	/// if there is one, otherwise attempts to create a new one.
	fn get_vm_payload_service() -> Result<Strong<dyn IVmPayloadService>> {
	let mut connection = PAYLOAD_CONNECTION.lock().unwrap();
	if let Some(strong) = &*connection {
	Ok(strong.clone())
	} else {
	let new_connection: Strong<dyn IVmPayloadService> = RpcSession::new()
	.setup_unix_domain_client(VM_PAYLOAD_SERVICE_SOCKET_NAME)
	.context(format!("Failed to connect to service: {}", VM_PAYLOAD_SERVICE_SOCKET_NAME))?;
	*connection = Some(new_connection.clone());
	Ok(new_connection)
	}
	}

	/// Make sure our logging goes to logcat. It is harmless to call this more than once.
	fn initialize_logging() {
	android_logger::init_once(
	android_logger::Config::default().with_tag("vm_payload").with_min_level(Level::Info),
	);
	}

	/// In many cases clients can't do anything useful if API calls fail, and the failure
	/// generally indicates that the VM is exiting or otherwise doomed. So rather than
	/// returning a non-actionable error indication we just log the problem and abort
	/// the process.
	fn unwrap_or_abort<T, E: Debug>(result: Result<T, E>) -> T {
	result.unwrap_or_else(\|e\| {
	let msg = format!("{:?}", e);
	error!("{msg}");
	panic!("{msg}")
	})
	}

	/// Notifies the host that the payload is ready.
	/// Panics on failure.
	#[no_mangle]
	pub extern "C" fn AVmPayload_notifyPayloadReady() {
	initialize_logging();

	if !ALREADY_NOTIFIED.swap(true, Ordering::Relaxed) {
	unwrap_or_abort(try_notify_payload_ready());

	info!("Notified host payload ready successfully");
	}
	}

	/// Notifies the host that the payload is ready.
	/// Returns a `Result` containing error information if failed.
	fn try_notify_payload_ready() -> Result<()> {
	get_vm_payload_service()?.notifyPayloadReady().context("Cannot notify payload ready")
	}

	/// Runs a binder RPC server, serving the supplied binder service implementation on the given vsock
	/// port.
	///
	/// If and when the server is ready for connections (it is listening on the port), `on_ready` is
	/// called to allow appropriate action to be taken - e.g. to notify clients that they may now
	/// attempt to connect.
	///
	/// The current thread joins the binder thread pool to handle incoming messages.
	/// This function never returns.
	///
	/// Panics on error (including unexpected server exit).
	///
	/// # Safety
	///
	/// If present, the `on_ready` callback must be a valid function pointer, which will be called at
	/// most once, while this function is executing, with the `param` parameter.
	#[no_mangle]
	pub unsafe extern "C" fn AVmPayload_runVsockRpcServer(
	service: *mut AIBinder,
	port: u32,
	on_ready: Option<unsafe extern "C" fn(param: *mut c_void)>,
	param: *mut c_void,
	) -> Infallible {
	initialize_logging();

	// SAFETY: try_run_vsock_server has the same requirements as this function
	unwrap_or_abort(unsafe { try_run_vsock_server(service, port, on_ready, param) })
	}

	/// # Safety: Same as `AVmPayload_runVsockRpcServer`.
	unsafe fn try_run_vsock_server(
	service: *mut AIBinder,
	port: u32,
	on_ready: Option<unsafe extern "C" fn(param: *mut c_void)>,
	param: *mut c_void,
	) -> Result<Infallible> {
	// SAFETY: AIBinder returned has correct reference count, and the ownership can
	// safely be taken by new_spibinder.
	let service = unsafe { new_spibinder(service) };
	if let Some(service) = service {
	match RpcServer::new_vsock(service, libc::VMADDR_CID_HOST, port) {
	Ok(server) => {
	if let Some(on_ready) = on_ready {
	// SAFETY: We're calling the callback with the parameter specified within the
	// allowed lifetime.
	unsafe { on_ready(param) };
	}
	server.join();
	bail!("RpcServer unexpectedly terminated");
	}
	Err(err) => {
	bail!("Failed to start RpcServer: {:?}", err);
	}
	}
	} else {
	bail!("Failed to convert the given service from AIBinder to SpIBinder.");
	}
	}

	/// Get a secret that is uniquely bound to this VM instance.
	/// Panics on failure.
	///
	/// # Safety
	///
	/// Behavior is undefined if any of the following conditions are violated:
	///
	/// * `identifier` must be [valid] for reads of `identifier_size` bytes.
	/// * `secret` must be [valid] for writes of `size` bytes.
	///
	/// [valid]: ptr#safety
	#[no_mangle]
	pub unsafe extern "C" fn AVmPayload_getVmInstanceSecret(
	identifier: *const u8,
	identifier_size: usize,
	secret: *mut u8,
	size: usize,
	) {
	initialize_logging();

	// SAFETY: See the requirements on `identifier` above.
	let identifier = unsafe { std::slice::from_raw_parts(identifier, identifier_size) };
	let vm_secret = unwrap_or_abort(try_get_vm_instance_secret(identifier, size));

	// SAFETY: See the requirements on `secret` above; `vm_secret` is known to have length `size`,
	// and cannot overlap `secret` because we just allocated it.
	unsafe {
	ptr::copy_nonoverlapping(vm_secret.as_ptr(), secret, size);
	}
	}

	fn try_get_vm_instance_secret(identifier: &[u8], size: usize) -> Result<Vec<u8>> {
	let vm_secret = get_vm_payload_service()?
	.getVmInstanceSecret(identifier, i32::try_from(size)?)
	.context("Cannot get VM instance secret")?;
	ensure!(
	vm_secret.len() == size,
	"Returned secret has {} bytes, expected {}",
	vm_secret.len(),
	size
	);
	Ok(vm_secret)
	}

	/// Get the VM's attestation chain.
	/// Panics on failure.
	///
	/// # Safety
	///
	/// Behavior is undefined if any of the following conditions are violated:
	///
	/// * `data` must be [valid] for writes of `size` bytes, if size > 0.
	///
	/// [valid]: ptr#safety
	#[no_mangle]
	pub unsafe extern "C" fn AVmPayload_getDiceAttestationChain(data: *mut u8, size: usize) -> usize {
	initialize_logging();

	let chain = unwrap_or_abort(try_get_dice_attestation_chain());
	if size != 0 {
	// SAFETY: See the requirements on `data` above. The number of bytes copied doesn't exceed
	// the length of either buffer, and `chain` cannot overlap `data` because we just allocated
	// it. We allow data to be null, which is never valid, but only if size == 0 which is
	// checked above.
	unsafe { ptr::copy_nonoverlapping(chain.as_ptr(), data, std::cmp::min(chain.len(), size)) };
	}
	chain.len()
	}

	fn try_get_dice_attestation_chain() -> Result<Vec<u8>> {
	get_vm_payload_service()?.getDiceAttestationChain().context("Cannot get attestation chain")
	}

	/// Get the VM's attestation CDI.
	/// Panics on failure.
	///
	/// # Safety
	///
	/// Behavior is undefined if any of the following conditions are violated:
	///
	/// * `data` must be [valid] for writes of `size` bytes, if size > 0.
	///
	/// [valid]: ptr#safety
	#[no_mangle]
	pub unsafe extern "C" fn AVmPayload_getDiceAttestationCdi(data: *mut u8, size: usize) -> usize {
	initialize_logging();

	let cdi = unwrap_or_abort(try_get_dice_attestation_cdi());
	if size != 0 {
	// SAFETY: See the requirements on `data` above. The number of bytes copied doesn't exceed
	// the length of either buffer, and `cdi` cannot overlap `data` because we just allocated
	// it. We allow data to be null, which is never valid, but only if size == 0 which is
	// checked above.
	unsafe { ptr::copy_nonoverlapping(cdi.as_ptr(), data, std::cmp::min(cdi.len(), size)) };
	}
	cdi.len()
	}

	fn try_get_dice_attestation_cdi() -> Result<Vec<u8>> {
	get_vm_payload_service()?.getDiceAttestationCdi().context("Cannot get attestation CDI")
	}

	/// Requests the remote attestation of the client VM.
	///
	/// The challenge will be included in the certificate chain in the attestation result,
	/// serving as proof of the freshness of the result.
	///
	/// # Safety
	///
	/// Behavior is undefined if any of the following conditions are violated:
	///
	/// * `challenge` must be [valid] for reads of `challenge_size` bytes.
	/// * `res` must be [valid] to write the attestation result.
	/// * The region of memory beginning at `challenge` with `challenge_size` bytes must not
	/// overlap with the region of memory `res` points to.
	///
	/// [valid]: ptr#safety
	#[no_mangle]
	pub unsafe extern "C" fn AVmPayload_requestAttestation(
	challenge: *const u8,
	challenge_size: usize,
	res: &mut *mut AttestationResult,
	) -> attestation_status_t {
	initialize_logging();
	const MAX_CHALLENGE_SIZE: usize = 64;
	if challenge_size > MAX_CHALLENGE_SIZE {
	return attestation_status_t::ATTESTATION_ERROR_INVALID_CHALLENGE;
	}
	let challenge = if challenge_size == 0 {
	&[]
	} else {
	// SAFETY: The caller guarantees that `challenge` is valid for reads of
	// `challenge_size` bytes and `challenge_size` is not zero.
	unsafe { std::slice::from_raw_parts(challenge, challenge_size) }
	};
	let attestation_res = unwrap_or_abort(try_request_attestation(challenge));
	*res = Box::into_raw(Box::new(attestation_res));
	attestation_status_t::ATTESTATION_OK
	}

	fn try_request_attestation(public_key: &[u8]) -> Result<AttestationResult> {
	get_vm_payload_service()?
	.requestAttestation(public_key)
	.context("Failed to request attestation")
	}

	/// Converts the return value from `AVmPayload_requestAttestation` to a text string
	/// representing the error code.
	#[no_mangle]
	pub extern "C" fn AVmAttestationResult_resultToString(
	status: attestation_status_t,
	) -> *const c_char {
	let message = match status {
	attestation_status_t::ATTESTATION_OK => {
	CStr::from_bytes_with_nul(b"The remote attestation completes successfully.\0").unwrap()
	}
	attestation_status_t::ATTESTATION_ERROR_INVALID_CHALLENGE => {
	CStr::from_bytes_with_nul(b"The challenge size is not between 0 and 64.\0").unwrap()
	}
	_ => CStr::from_bytes_with_nul(
	b"The remote attestation has failed due to an unspecified cause.\0",
	)
	.unwrap(),
	};
	message.as_ptr()
	}

	/// Reads the DER-encoded ECPrivateKey structure specified in [RFC 5915 s3] for the
	/// EC P-256 private key from the provided attestation result.
	///
	/// # Safety
	///
	/// Behavior is undefined if any of the following conditions are violated:
	///
	/// * `data` must be [valid] for writes of `size` bytes, if size > 0.
	/// * The region of memory beginning at `data` with `size` bytes must not overlap with the
	/// region of memory `res` points to.
	///
	/// [valid]: ptr#safety
	/// [RFC 5915 s3]: https://datatracker.ietf.org/doc/html/rfc5915#section-3
	#[no_mangle]
	pub unsafe extern "C" fn AVmAttestationResult_getPrivateKey(
	res: &AttestationResult,
	data: *mut u8,
	size: usize,
	) -> usize {
	let private_key = &res.privateKey;
	if size != 0 {
	let data = NonNull::new(data).expect("data must not be null when size > 0");
	// SAFETY: See the requirements on `data` above. The number of bytes copied doesn't exceed
	// the length of either buffer, and the caller ensures that `private_key` cannot overlap
	// `data`. We allow data to be null, which is never valid, but only if size == 0
	// which is checked above.
	unsafe {
	ptr::copy_nonoverlapping(
	private_key.as_ptr(),
	data.as_ptr(),
	std::cmp::min(private_key.len(), size),
	)
	};
	}
	private_key.len()
	}

	/// Signs the given message using ECDSA P-256, the message is first hashed with SHA-256 and
	/// then it is signed with the attested EC P-256 private key in the attestation result.
	///
	/// # Safety
	///
	/// Behavior is undefined if any of the following conditions are violated:
	///
	/// * `message` must be [valid] for reads of `message_size` bytes.
	/// * `data` must be [valid] for writes of `size` bytes, if size > 0.
	/// * The region of memory beginning at `data` with `size` bytes must not overlap with the
	/// region of memory `res` or `message` point to.
	///
	///
	/// [valid]: ptr#safety
	#[no_mangle]
	pub unsafe extern "C" fn AVmAttestationResult_sign(
	res: &AttestationResult,
	message: *const u8,
	message_size: usize,
	data: *mut u8,
	size: usize,
	) -> usize {
	if message_size == 0 {
	panic!("Message to be signed must not be empty.")
	}
	// SAFETY: See the requirements on `message` above.
	let message = unsafe { std::slice::from_raw_parts(message, message_size) };
	let signature = unwrap_or_abort(try_ecdsa_sign(message, &res.privateKey));
	if size != 0 {
	let data = NonNull::new(data).expect("data must not be null when size > 0");
	// SAFETY: See the requirements on `data` above. The number of bytes copied doesn't exceed
	// the length of either buffer, and the caller ensures that `signature` cannot overlap
	// `data`. We allow data to be null, which is never valid, but only if size == 0
	// which is checked above.
	unsafe {
	ptr::copy_nonoverlapping(
	signature.as_ptr(),
	data.as_ptr(),
	std::cmp::min(signature.len(), size),
	)
	};
	}
	signature.len()
	}

	fn try_ecdsa_sign(message: &[u8], der_encoded_ec_private_key: &[u8]) -> Result<Vec<u8>> {
	let private_key = EcKey::private_key_from_der(der_encoded_ec_private_key)?;
	let digest = sha256(message);
	let sig = EcdsaSig::sign(&digest, &private_key)?;
	Ok(sig.to_der()?)
	}

	/// Gets the number of certificates in the certificate chain.
	#[no_mangle]
	pub extern "C" fn AVmAttestationResult_getCertificateCount(res: &AttestationResult) -> usize {
	res.certificateChain.len()
	}

	/// Retrieves the certificate at the given `index` from the certificate chain in the provided
	/// attestation result.
	///
	/// # Safety
	///
	/// Behavior is undefined if any of the following conditions are violated:
	///
	/// * `data` must be [valid] for writes of `size` bytes, if size > 0.
	/// * `index` must be within the range of [0, number of certificates). The number of certificates
	/// can be obtained with `AVmAttestationResult_getCertificateCount`.
	/// * The region of memory beginning at `data` with `size` bytes must not overlap with the
	/// region of memory `res` points to.
	///
	/// [valid]: ptr#safety
	#[no_mangle]
	pub unsafe extern "C" fn AVmAttestationResult_getCertificateAt(
	res: &AttestationResult,
	index: usize,
	data: *mut u8,
	size: usize,
	) -> usize {
	let certificate =
	&res.certificateChain.get(index).expect("The index is out of bounds.").encodedCertificate;
	if size != 0 {
	let data = NonNull::new(data).expect("data must not be null when size > 0");
	// SAFETY: See the requirements on `data` above. The number of bytes copied doesn't exceed
	// the length of either buffer, and the caller ensures that `certificate` cannot overlap
	// `data`. We allow data to be null, which is never valid, but only if size == 0
	// which is checked above.
	unsafe {
	ptr::copy_nonoverlapping(
	certificate.as_ptr(),
	data.as_ptr(),
	std::cmp::min(certificate.len(), size),
	)
	};
	}
	certificate.len()
	}

	/// Frees all the data owned by given attestation result and result itself.
	///
	/// # Safety
	///
	/// Behavior is undefined if any of the following conditions are violated:
	///
	/// * `res` must point to a valid `AttestationResult` and has not been freed before.
	#[no_mangle]
	pub unsafe extern "C" fn AVmAttestationResult_free(res: *mut AttestationResult) {
	if !res.is_null() {
	// SAFETY: The result is only freed once is ensured by the caller.
	let res = unsafe { Box::from_raw(res) };
	drop(res)
	}
	}

	/// Gets the path to the APK contents.
	#[no_mangle]
	pub extern "C" fn AVmPayload_getApkContentsPath() -> *const c_char {
	VM_APK_CONTENTS_PATH_C.as_ptr()
	}

	/// Gets the path to the VM's encrypted storage.
	#[no_mangle]
	pub extern "C" fn AVmPayload_getEncryptedStoragePath() -> *const c_char {
	if Path::new(ENCRYPTEDSTORE_MOUNTPOINT).exists() {
	VM_ENCRYPTED_STORAGE_PATH_C.as_ptr()
	} else {
	ptr::null()
	}
	}