| // Copyright 2020, 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 is the Keystore 2.0 Enforcements module. |
| // TODO: more description to follow. |
| use crate::error::{map_binder_status, Error, ErrorCode}; |
| use crate::globals::{get_timestamp_service, ASYNC_TASK, DB, ENFORCEMENTS}; |
| use crate::key_parameter::{KeyParameter, KeyParameterValue}; |
| use crate::{authorization::Error as AuthzError, super_key::SuperEncryptionType}; |
| use crate::{ |
| database::{AuthTokenEntry, MonotonicRawTime}, |
| globals::SUPER_KEY, |
| }; |
| use android_hardware_security_keymint::aidl::android::hardware::security::keymint::{ |
| Algorithm::Algorithm, ErrorCode::ErrorCode as Ec, HardwareAuthToken::HardwareAuthToken, |
| HardwareAuthenticatorType::HardwareAuthenticatorType, |
| KeyParameter::KeyParameter as KmKeyParameter, KeyPurpose::KeyPurpose, Tag::Tag, |
| }; |
| use android_hardware_security_secureclock::aidl::android::hardware::security::secureclock::{ |
| TimeStampToken::TimeStampToken, |
| }; |
| use android_security_authorization::aidl::android::security::authorization::ResponseCode::ResponseCode as AuthzResponseCode; |
| use android_system_keystore2::aidl::android::system::keystore2::{ |
| Domain::Domain, IKeystoreSecurityLevel::KEY_FLAG_AUTH_BOUND_WITHOUT_CRYPTOGRAPHIC_LSKF_BINDING, |
| OperationChallenge::OperationChallenge, |
| }; |
| use anyhow::{Context, Result}; |
| use std::{ |
| collections::{HashMap, HashSet}, |
| sync::{ |
| mpsc::{channel, Receiver, Sender, TryRecvError}, |
| Arc, Mutex, Weak, |
| }, |
| time::SystemTime, |
| }; |
| |
| #[derive(Debug)] |
| enum AuthRequestState { |
| /// An outstanding per operation authorization request. |
| OpAuth, |
| /// An outstanding request for per operation authorization and secure timestamp. |
| TimeStampedOpAuth(Receiver<Result<TimeStampToken, Error>>), |
| /// An outstanding request for a timestamp token. |
| TimeStamp(Receiver<Result<TimeStampToken, Error>>), |
| } |
| |
| #[derive(Debug)] |
| struct AuthRequest { |
| state: AuthRequestState, |
| /// This need to be set to Some to fulfill a AuthRequestState::OpAuth or |
| /// AuthRequestState::TimeStampedOpAuth. |
| hat: Mutex<Option<HardwareAuthToken>>, |
| } |
| |
| unsafe impl Sync for AuthRequest {} |
| |
| impl AuthRequest { |
| fn op_auth() -> Arc<Self> { |
| Arc::new(Self { state: AuthRequestState::OpAuth, hat: Mutex::new(None) }) |
| } |
| |
| fn timestamped_op_auth(receiver: Receiver<Result<TimeStampToken, Error>>) -> Arc<Self> { |
| Arc::new(Self { |
| state: AuthRequestState::TimeStampedOpAuth(receiver), |
| hat: Mutex::new(None), |
| }) |
| } |
| |
| fn timestamp( |
| hat: HardwareAuthToken, |
| receiver: Receiver<Result<TimeStampToken, Error>>, |
| ) -> Arc<Self> { |
| Arc::new(Self { state: AuthRequestState::TimeStamp(receiver), hat: Mutex::new(Some(hat)) }) |
| } |
| |
| fn add_auth_token(&self, hat: HardwareAuthToken) { |
| *self.hat.lock().unwrap() = Some(hat) |
| } |
| |
| fn get_auth_tokens(&self) -> Result<(HardwareAuthToken, Option<TimeStampToken>)> { |
| let hat = self |
| .hat |
| .lock() |
| .unwrap() |
| .take() |
| .ok_or(Error::Km(ErrorCode::KEY_USER_NOT_AUTHENTICATED)) |
| .context("In get_auth_tokens: No operation auth token received.")?; |
| |
| let tst = match &self.state { |
| AuthRequestState::TimeStampedOpAuth(recv) | AuthRequestState::TimeStamp(recv) => { |
| let result = recv.recv().context("In get_auth_tokens: Sender disconnected.")?; |
| Some(result.context(concat!( |
| "In get_auth_tokens: Worker responded with error ", |
| "from generating timestamp token." |
| ))?) |
| } |
| AuthRequestState::OpAuth => None, |
| }; |
| Ok((hat, tst)) |
| } |
| } |
| |
| /// DeferredAuthState describes how auth tokens and timestamp tokens need to be provided when |
| /// updating and finishing an operation. |
| #[derive(Debug)] |
| enum DeferredAuthState { |
| /// Used when an operation does not require further authorization. |
| NoAuthRequired, |
| /// Indicates that the operation requires an operation specific token. This means we have |
| /// to return an operation challenge to the client which should reward us with an |
| /// operation specific auth token. If it is not provided before the client calls update |
| /// or finish, the operation fails as not authorized. |
| OpAuthRequired, |
| /// Indicates that the operation requires a time stamp token. The auth token was already |
| /// loaded from the database, but it has to be accompanied by a time stamp token to inform |
| /// the target KM with a different clock about the time on the authenticators. |
| TimeStampRequired(HardwareAuthToken), |
| /// Indicates that both an operation bound auth token and a verification token are |
| /// before the operation can commence. |
| TimeStampedOpAuthRequired, |
| /// In this state the auth info is waiting for the deferred authorizations to come in. |
| /// We block on timestamp tokens, because we can always make progress on these requests. |
| /// The per-op auth tokens might never come, which means we fail if the client calls |
| /// update or finish before we got a per-op auth token. |
| Waiting(Arc<AuthRequest>), |
| /// In this state we have gotten all of the required tokens, we just cache them to |
| /// be used when the operation progresses. |
| Token(HardwareAuthToken, Option<TimeStampToken>), |
| } |
| |
| /// Auth info hold all of the authorization related information of an operation. It is stored |
| /// in and owned by the operation. It is constructed by authorize_create and stays with the |
| /// operation until it completes. |
| #[derive(Debug)] |
| pub struct AuthInfo { |
| state: DeferredAuthState, |
| /// An optional key id required to update the usage count if the key usage is limited. |
| key_usage_limited: Option<i64>, |
| confirmation_token_receiver: Option<Arc<Mutex<Option<Receiver<Vec<u8>>>>>>, |
| } |
| |
| struct TokenReceiverMap { |
| /// The map maps an outstanding challenge to a TokenReceiver. If an incoming Hardware Auth |
| /// Token (HAT) has the map key in its challenge field, it gets passed to the TokenReceiver |
| /// and the entry is removed from the map. In the case where no HAT is received before the |
| /// corresponding operation gets dropped, the entry goes stale. So every time the cleanup |
| /// counter (second field in the tuple) turns 0, the map is cleaned from stale entries. |
| /// The cleanup counter is decremented every time a new receiver is added. |
| /// and reset to TokenReceiverMap::CLEANUP_PERIOD + 1 after each cleanup. |
| map_and_cleanup_counter: Mutex<(HashMap<i64, TokenReceiver>, u8)>, |
| } |
| |
| impl Default for TokenReceiverMap { |
| fn default() -> Self { |
| Self { map_and_cleanup_counter: Mutex::new((HashMap::new(), Self::CLEANUP_PERIOD + 1)) } |
| } |
| } |
| |
| impl TokenReceiverMap { |
| /// There is a chance that receivers may become stale because their operation is dropped |
| /// without ever being authorized. So occasionally we iterate through the map and throw |
| /// out obsolete entries. |
| /// This is the number of calls to add_receiver between cleanups. |
| const CLEANUP_PERIOD: u8 = 25; |
| |
| pub fn add_auth_token(&self, hat: HardwareAuthToken) { |
| let recv = { |
| // Limit the scope of the mutex guard, so that it is not held while the auth token is |
| // added. |
| let mut map = self.map_and_cleanup_counter.lock().unwrap(); |
| let (ref mut map, _) = *map; |
| map.remove_entry(&hat.challenge) |
| }; |
| |
| if let Some((_, recv)) = recv { |
| recv.add_auth_token(hat); |
| } |
| } |
| |
| pub fn add_receiver(&self, challenge: i64, recv: TokenReceiver) { |
| let mut map = self.map_and_cleanup_counter.lock().unwrap(); |
| let (ref mut map, ref mut cleanup_counter) = *map; |
| map.insert(challenge, recv); |
| |
| *cleanup_counter -= 1; |
| if *cleanup_counter == 0 { |
| map.retain(|_, v| !v.is_obsolete()); |
| map.shrink_to_fit(); |
| *cleanup_counter = Self::CLEANUP_PERIOD + 1; |
| } |
| } |
| } |
| |
| #[derive(Debug)] |
| struct TokenReceiver(Weak<AuthRequest>); |
| |
| impl TokenReceiver { |
| fn is_obsolete(&self) -> bool { |
| self.0.upgrade().is_none() |
| } |
| |
| fn add_auth_token(&self, hat: HardwareAuthToken) { |
| if let Some(state_arc) = self.0.upgrade() { |
| state_arc.add_auth_token(hat); |
| } |
| } |
| } |
| |
| fn get_timestamp_token(challenge: i64) -> Result<TimeStampToken, Error> { |
| let dev = get_timestamp_service().expect(concat!( |
| "Secure Clock service must be present ", |
| "if TimeStampTokens are required." |
| )); |
| map_binder_status(dev.generateTimeStamp(challenge)) |
| } |
| |
| fn timestamp_token_request(challenge: i64, sender: Sender<Result<TimeStampToken, Error>>) { |
| if let Err(e) = sender.send(get_timestamp_token(challenge)) { |
| log::info!( |
| concat!( |
| "In timestamp_token_request: Receiver hung up ", |
| "before timestamp token could be delivered. {:?}" |
| ), |
| e |
| ); |
| } |
| } |
| |
| impl AuthInfo { |
| /// This function gets called after an operation was successfully created. |
| /// It makes all the preparations required, so that the operation has all the authentication |
| /// related artifacts to advance on update and finish. |
| pub fn finalize_create_authorization(&mut self, challenge: i64) -> Option<OperationChallenge> { |
| match &self.state { |
| DeferredAuthState::OpAuthRequired => { |
| let auth_request = AuthRequest::op_auth(); |
| let token_receiver = TokenReceiver(Arc::downgrade(&auth_request)); |
| ENFORCEMENTS.register_op_auth_receiver(challenge, token_receiver); |
| |
| self.state = DeferredAuthState::Waiting(auth_request); |
| Some(OperationChallenge { challenge }) |
| } |
| DeferredAuthState::TimeStampedOpAuthRequired => { |
| let (sender, receiver) = channel::<Result<TimeStampToken, Error>>(); |
| let auth_request = AuthRequest::timestamped_op_auth(receiver); |
| let token_receiver = TokenReceiver(Arc::downgrade(&auth_request)); |
| ENFORCEMENTS.register_op_auth_receiver(challenge, token_receiver); |
| |
| ASYNC_TASK.queue_hi(move |_| timestamp_token_request(challenge, sender)); |
| self.state = DeferredAuthState::Waiting(auth_request); |
| Some(OperationChallenge { challenge }) |
| } |
| DeferredAuthState::TimeStampRequired(hat) => { |
| let hat = (*hat).clone(); |
| let (sender, receiver) = channel::<Result<TimeStampToken, Error>>(); |
| let auth_request = AuthRequest::timestamp(hat, receiver); |
| ASYNC_TASK.queue_hi(move |_| timestamp_token_request(challenge, sender)); |
| self.state = DeferredAuthState::Waiting(auth_request); |
| None |
| } |
| _ => None, |
| } |
| } |
| |
| /// This function is the authorization hook called before operation update. |
| /// It returns the auth tokens required by the operation to commence update. |
| pub fn before_update(&mut self) -> Result<(Option<HardwareAuthToken>, Option<TimeStampToken>)> { |
| self.get_auth_tokens() |
| } |
| |
| /// This function is the authorization hook called before operation finish. |
| /// It returns the auth tokens required by the operation to commence finish. |
| /// The third token is a confirmation token. |
| pub fn before_finish( |
| &mut self, |
| ) -> Result<(Option<HardwareAuthToken>, Option<TimeStampToken>, Option<Vec<u8>>)> { |
| let mut confirmation_token: Option<Vec<u8>> = None; |
| if let Some(ref confirmation_token_receiver) = self.confirmation_token_receiver { |
| let locked_receiver = confirmation_token_receiver.lock().unwrap(); |
| if let Some(ref receiver) = *locked_receiver { |
| loop { |
| match receiver.try_recv() { |
| // As long as we get tokens we loop and discard all but the most |
| // recent one. |
| Ok(t) => confirmation_token = Some(t), |
| Err(TryRecvError::Empty) => break, |
| Err(TryRecvError::Disconnected) => { |
| log::error!(concat!( |
| "We got disconnected from the APC service, ", |
| "this should never happen." |
| )); |
| break; |
| } |
| } |
| } |
| } |
| } |
| self.get_auth_tokens().map(|(hat, tst)| (hat, tst, confirmation_token)) |
| } |
| |
| /// This function is the authorization hook called after finish succeeded. |
| /// As of this writing it checks if the key was a limited use key. If so it updates the |
| /// use counter of the key in the database. When the use counter is depleted, the key gets |
| /// marked for deletion and the garbage collector is notified. |
| pub fn after_finish(&self) -> Result<()> { |
| if let Some(key_id) = self.key_usage_limited { |
| // On the last successful use, the key gets deleted. In this case we |
| // have to notify the garbage collector. |
| DB.with(|db| { |
| db.borrow_mut() |
| .check_and_update_key_usage_count(key_id) |
| .context("Trying to update key usage count.") |
| }) |
| .context("In after_finish.")?; |
| } |
| Ok(()) |
| } |
| |
| /// This function returns the auth tokens as needed by the ongoing operation or fails |
| /// with ErrorCode::KEY_USER_NOT_AUTHENTICATED. If this was called for the first time |
| /// after a deferred authorization was requested by finalize_create_authorization, this |
| /// function may block on the generation of a time stamp token. It then moves the |
| /// tokens into the DeferredAuthState::Token state for future use. |
| fn get_auth_tokens(&mut self) -> Result<(Option<HardwareAuthToken>, Option<TimeStampToken>)> { |
| let deferred_tokens = if let DeferredAuthState::Waiting(ref auth_request) = self.state { |
| Some(auth_request.get_auth_tokens().context("In AuthInfo::get_auth_tokens.")?) |
| } else { |
| None |
| }; |
| |
| if let Some((hat, tst)) = deferred_tokens { |
| self.state = DeferredAuthState::Token(hat, tst); |
| } |
| |
| match &self.state { |
| DeferredAuthState::NoAuthRequired => Ok((None, None)), |
| DeferredAuthState::Token(hat, tst) => Ok((Some((*hat).clone()), (*tst).clone())), |
| DeferredAuthState::OpAuthRequired |
| | DeferredAuthState::TimeStampedOpAuthRequired |
| | DeferredAuthState::TimeStampRequired(_) => { |
| Err(Error::Km(ErrorCode::KEY_USER_NOT_AUTHENTICATED)).context(concat!( |
| "In AuthInfo::get_auth_tokens: No operation auth token requested??? ", |
| "This should not happen." |
| )) |
| } |
| // This should not be reachable, because it should have been handled above. |
| DeferredAuthState::Waiting(_) => { |
| Err(Error::sys()).context("In AuthInfo::get_auth_tokens: Cannot be reached.") |
| } |
| } |
| } |
| } |
| |
| /// Enforcements data structure |
| #[derive(Default)] |
| pub struct Enforcements { |
| /// This hash set contains the user ids for whom the device is currently unlocked. If a user id |
| /// is not in the set, it implies that the device is locked for the user. |
| device_unlocked_set: Mutex<HashSet<i32>>, |
| /// This field maps outstanding auth challenges to their operations. When an auth token |
| /// with the right challenge is received it is passed to the map using |
| /// TokenReceiverMap::add_auth_token() which removes the entry from the map. If an entry goes |
| /// stale, because the operation gets dropped before an auth token is received, the map |
| /// is cleaned up in regular intervals. |
| op_auth_map: TokenReceiverMap, |
| /// The enforcement module will try to get a confirmation token from this channel whenever |
| /// an operation that requires confirmation finishes. |
| confirmation_token_receiver: Arc<Mutex<Option<Receiver<Vec<u8>>>>>, |
| } |
| |
| impl Enforcements { |
| /// Install the confirmation token receiver. The enforcement module will try to get a |
| /// confirmation token from this channel whenever an operation that requires confirmation |
| /// finishes. |
| pub fn install_confirmation_token_receiver( |
| &self, |
| confirmation_token_receiver: Receiver<Vec<u8>>, |
| ) { |
| *self.confirmation_token_receiver.lock().unwrap() = Some(confirmation_token_receiver); |
| } |
| |
| /// Checks if a create call is authorized, given key parameters and operation parameters. |
| /// It returns an optional immediate auth token which can be presented to begin, and an |
| /// AuthInfo object which stays with the authorized operation and is used to obtain |
| /// auth tokens and timestamp tokens as required by the operation. |
| /// With regard to auth tokens, the following steps are taken: |
| /// |
| /// If no key parameters are given (typically when the client is self managed |
| /// (see Domain.Blob)) nothing is enforced. |
| /// If the key is time-bound, find a matching auth token from the database. |
| /// If the above step is successful, and if requires_timestamp is given, the returned |
| /// AuthInfo will provide a Timestamp token as appropriate. |
| pub fn authorize_create( |
| &self, |
| purpose: KeyPurpose, |
| key_properties: Option<&(i64, Vec<KeyParameter>)>, |
| op_params: &[KmKeyParameter], |
| requires_timestamp: bool, |
| ) -> Result<(Option<HardwareAuthToken>, AuthInfo)> { |
| let (key_id, key_params) = match key_properties { |
| Some((key_id, key_params)) => (*key_id, key_params), |
| None => { |
| return Ok(( |
| None, |
| AuthInfo { |
| state: DeferredAuthState::NoAuthRequired, |
| key_usage_limited: None, |
| confirmation_token_receiver: None, |
| }, |
| )) |
| } |
| }; |
| |
| match purpose { |
| // Allow SIGN, DECRYPT for both symmetric and asymmetric keys. |
| KeyPurpose::SIGN | KeyPurpose::DECRYPT => {} |
| // Rule out WRAP_KEY purpose |
| KeyPurpose::WRAP_KEY => { |
| return Err(Error::Km(Ec::INCOMPATIBLE_PURPOSE)) |
| .context("In authorize_create: WRAP_KEY purpose is not allowed here."); |
| } |
| // Allow AGREE_KEY for EC keys only. |
| KeyPurpose::AGREE_KEY => { |
| for kp in key_params.iter() { |
| if kp.get_tag() == Tag::ALGORITHM |
| && *kp.key_parameter_value() != KeyParameterValue::Algorithm(Algorithm::EC) |
| { |
| return Err(Error::Km(Ec::UNSUPPORTED_PURPOSE)).context( |
| "In authorize_create: key agreement is only supported for EC keys.", |
| ); |
| } |
| } |
| } |
| KeyPurpose::VERIFY | KeyPurpose::ENCRYPT => { |
| // We do not support ENCRYPT and VERIFY (the remaining two options of purpose) for |
| // asymmetric keys. |
| for kp in key_params.iter() { |
| match *kp.key_parameter_value() { |
| KeyParameterValue::Algorithm(Algorithm::RSA) |
| | KeyParameterValue::Algorithm(Algorithm::EC) => { |
| return Err(Error::Km(Ec::UNSUPPORTED_PURPOSE)).context( |
| "In authorize_create: public operations on asymmetric keys are not |
| supported.", |
| ); |
| } |
| _ => {} |
| } |
| } |
| } |
| _ => { |
| return Err(Error::Km(Ec::UNSUPPORTED_PURPOSE)) |
| .context("In authorize_create: specified purpose is not supported."); |
| } |
| } |
| // The following variables are to record information from key parameters to be used in |
| // enforcements, when two or more such pieces of information are required for enforcements. |
| // There is only one additional variable than what legacy keystore has, but this helps |
| // reduce the number of for loops on key parameters from 3 to 1, compared to legacy keystore |
| let mut key_purpose_authorized: bool = false; |
| let mut user_auth_type: Option<HardwareAuthenticatorType> = None; |
| let mut no_auth_required: bool = false; |
| let mut caller_nonce_allowed = false; |
| let mut user_id: i32 = -1; |
| let mut user_secure_ids = Vec::<i64>::new(); |
| let mut key_time_out: Option<i64> = None; |
| let mut allow_while_on_body = false; |
| let mut unlocked_device_required = false; |
| let mut key_usage_limited: Option<i64> = None; |
| let mut confirmation_token_receiver: Option<Arc<Mutex<Option<Receiver<Vec<u8>>>>>> = None; |
| let mut max_boot_level: Option<i32> = None; |
| |
| // iterate through key parameters, recording information we need for authorization |
| // enforcements later, or enforcing authorizations in place, where applicable |
| for key_param in key_params.iter() { |
| match key_param.key_parameter_value() { |
| KeyParameterValue::NoAuthRequired => { |
| no_auth_required = true; |
| } |
| KeyParameterValue::AuthTimeout(t) => { |
| key_time_out = Some(*t as i64); |
| } |
| KeyParameterValue::HardwareAuthenticatorType(a) => { |
| user_auth_type = Some(*a); |
| } |
| KeyParameterValue::KeyPurpose(p) => { |
| // The following check has the effect of key_params.contains(purpose) |
| // Also, authorizing purpose can not be completed here, if there can be multiple |
| // key parameters for KeyPurpose. |
| key_purpose_authorized = key_purpose_authorized || *p == purpose; |
| } |
| KeyParameterValue::CallerNonce => { |
| caller_nonce_allowed = true; |
| } |
| KeyParameterValue::ActiveDateTime(a) => { |
| if !Enforcements::is_given_time_passed(*a, true) { |
| return Err(Error::Km(Ec::KEY_NOT_YET_VALID)) |
| .context("In authorize_create: key is not yet active."); |
| } |
| } |
| KeyParameterValue::OriginationExpireDateTime(o) => { |
| if (purpose == KeyPurpose::ENCRYPT || purpose == KeyPurpose::SIGN) |
| && Enforcements::is_given_time_passed(*o, false) |
| { |
| return Err(Error::Km(Ec::KEY_EXPIRED)) |
| .context("In authorize_create: key is expired."); |
| } |
| } |
| KeyParameterValue::UsageExpireDateTime(u) => { |
| if (purpose == KeyPurpose::DECRYPT || purpose == KeyPurpose::VERIFY) |
| && Enforcements::is_given_time_passed(*u, false) |
| { |
| return Err(Error::Km(Ec::KEY_EXPIRED)) |
| .context("In authorize_create: key is expired."); |
| } |
| } |
| KeyParameterValue::UserSecureID(s) => { |
| user_secure_ids.push(*s); |
| } |
| KeyParameterValue::UserID(u) => { |
| user_id = *u; |
| } |
| KeyParameterValue::UnlockedDeviceRequired => { |
| unlocked_device_required = true; |
| } |
| KeyParameterValue::AllowWhileOnBody => { |
| allow_while_on_body = true; |
| } |
| KeyParameterValue::UsageCountLimit(_) => { |
| // We don't examine the limit here because this is enforced on finish. |
| // Instead, we store the key_id so that finish can look up the key |
| // in the database again and check and update the counter. |
| key_usage_limited = Some(key_id); |
| } |
| KeyParameterValue::TrustedConfirmationRequired => { |
| confirmation_token_receiver = Some(self.confirmation_token_receiver.clone()); |
| } |
| KeyParameterValue::MaxBootLevel(level) => { |
| max_boot_level = Some(*level); |
| } |
| // NOTE: as per offline discussion, sanitizing key parameters and rejecting |
| // create operation if any non-allowed tags are present, is not done in |
| // authorize_create (unlike in legacy keystore where AuthorizeBegin is rejected if |
| // a subset of non-allowed tags are present). Because sanitizing key parameters |
| // should have been done during generate/import key, by KeyMint. |
| _ => { /*Do nothing on all the other key parameters, as in legacy keystore*/ } |
| } |
| } |
| |
| // authorize the purpose |
| if !key_purpose_authorized { |
| return Err(Error::Km(Ec::INCOMPATIBLE_PURPOSE)) |
| .context("In authorize_create: the purpose is not authorized."); |
| } |
| |
| // if both NO_AUTH_REQUIRED and USER_SECURE_ID tags are present, return error |
| if !user_secure_ids.is_empty() && no_auth_required { |
| return Err(Error::Km(Ec::INVALID_KEY_BLOB)).context( |
| "In authorize_create: key has both NO_AUTH_REQUIRED |
| and USER_SECURE_ID tags.", |
| ); |
| } |
| |
| // if either of auth_type or secure_id is present and the other is not present, return error |
| if (user_auth_type.is_some() && user_secure_ids.is_empty()) |
| || (user_auth_type.is_none() && !user_secure_ids.is_empty()) |
| { |
| return Err(Error::Km(Ec::KEY_USER_NOT_AUTHENTICATED)).context( |
| "In authorize_create: Auth required, but either auth type or secure ids |
| are not present.", |
| ); |
| } |
| |
| // validate caller nonce for origination purposes |
| if (purpose == KeyPurpose::ENCRYPT || purpose == KeyPurpose::SIGN) |
| && !caller_nonce_allowed |
| && op_params.iter().any(|kp| kp.tag == Tag::NONCE) |
| { |
| return Err(Error::Km(Ec::CALLER_NONCE_PROHIBITED)).context( |
| "In authorize_create, NONCE is present, |
| although CALLER_NONCE is not present", |
| ); |
| } |
| |
| if unlocked_device_required { |
| // check the device locked status. If locked, operations on the key are not |
| // allowed. |
| if self.is_device_locked(user_id) { |
| return Err(Error::Km(Ec::DEVICE_LOCKED)) |
| .context("In authorize_create: device is locked."); |
| } |
| } |
| |
| if let Some(level) = max_boot_level { |
| if !SUPER_KEY.level_accessible(level) { |
| return Err(Error::Km(Ec::BOOT_LEVEL_EXCEEDED)) |
| .context("In authorize_create: boot level is too late."); |
| } |
| } |
| |
| if !unlocked_device_required && no_auth_required { |
| return Ok(( |
| None, |
| AuthInfo { |
| state: DeferredAuthState::NoAuthRequired, |
| key_usage_limited, |
| confirmation_token_receiver, |
| }, |
| )); |
| } |
| |
| let has_sids = !user_secure_ids.is_empty(); |
| |
| let timeout_bound = key_time_out.is_some() && has_sids; |
| |
| let per_op_bound = key_time_out.is_none() && has_sids; |
| |
| let need_auth_token = timeout_bound || unlocked_device_required; |
| |
| let hat_and_last_off_body = if need_auth_token { |
| let hat_and_last_off_body = Self::find_auth_token(|hat: &AuthTokenEntry| { |
| if let (Some(auth_type), true) = (user_auth_type, has_sids) { |
| hat.satisfies(&user_secure_ids, auth_type) |
| } else { |
| unlocked_device_required |
| } |
| }); |
| Some( |
| hat_and_last_off_body |
| .ok_or(Error::Km(Ec::KEY_USER_NOT_AUTHENTICATED)) |
| .context("In authorize_create: No suitable auth token found.")?, |
| ) |
| } else { |
| None |
| }; |
| |
| // Now check the validity of the auth token if the key is timeout bound. |
| let hat = match (hat_and_last_off_body, key_time_out) { |
| (Some((hat, last_off_body)), Some(key_time_out)) => { |
| let now = MonotonicRawTime::now(); |
| let token_age = now |
| .checked_sub(&hat.time_received()) |
| .ok_or_else(Error::sys) |
| .context(concat!( |
| "In authorize_create: Overflow while computing Auth token validity. ", |
| "Validity cannot be established." |
| ))?; |
| |
| let on_body_extended = allow_while_on_body && last_off_body < hat.time_received(); |
| |
| if token_age.seconds() > key_time_out && !on_body_extended { |
| return Err(Error::Km(Ec::KEY_USER_NOT_AUTHENTICATED)) |
| .context("In authorize_create: matching auth token is expired."); |
| } |
| Some(hat) |
| } |
| (Some((hat, _)), None) => Some(hat), |
| // If timeout_bound is true, above code must have retrieved a HAT or returned with |
| // KEY_USER_NOT_AUTHENTICATED. This arm should not be reachable. |
| (None, Some(_)) => panic!("Logical error."), |
| _ => None, |
| }; |
| |
| Ok(match (hat, requires_timestamp, per_op_bound) { |
| // Per-op-bound and Some(hat) can only happen if we are both per-op bound and unlocked |
| // device required. In addition, this KM instance needs a timestamp token. |
| // So the HAT cannot be presented on create. So on update/finish we present both |
| // an per-op-bound auth token and a timestamp token. |
| (Some(_), true, true) => (None, DeferredAuthState::TimeStampedOpAuthRequired), |
| (Some(hat), true, false) => ( |
| Some(hat.auth_token().clone()), |
| DeferredAuthState::TimeStampRequired(hat.take_auth_token()), |
| ), |
| (Some(hat), false, true) => { |
| (Some(hat.take_auth_token()), DeferredAuthState::OpAuthRequired) |
| } |
| (Some(hat), false, false) => { |
| (Some(hat.take_auth_token()), DeferredAuthState::NoAuthRequired) |
| } |
| (None, _, true) => (None, DeferredAuthState::OpAuthRequired), |
| (None, _, false) => (None, DeferredAuthState::NoAuthRequired), |
| }) |
| .map(|(hat, state)| { |
| (hat, AuthInfo { state, key_usage_limited, confirmation_token_receiver }) |
| }) |
| } |
| |
| fn find_auth_token<F>(p: F) -> Option<(AuthTokenEntry, MonotonicRawTime)> |
| where |
| F: Fn(&AuthTokenEntry) -> bool, |
| { |
| DB.with(|db| db.borrow().find_auth_token_entry(p)) |
| } |
| |
| /// Checks if the time now since epoch is greater than (or equal, if is_given_time_inclusive is |
| /// set) the given time (in milliseconds) |
| fn is_given_time_passed(given_time: i64, is_given_time_inclusive: bool) -> bool { |
| let duration_since_epoch = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH); |
| |
| let time_since_epoch = match duration_since_epoch { |
| Ok(duration) => duration.as_millis(), |
| Err(_) => return false, |
| }; |
| |
| if is_given_time_inclusive { |
| time_since_epoch >= (given_time as u128) |
| } else { |
| time_since_epoch > (given_time as u128) |
| } |
| } |
| |
| /// Check if the device is locked for the given user. If there's no entry yet for the user, |
| /// we assume that the device is locked |
| fn is_device_locked(&self, user_id: i32) -> bool { |
| // unwrap here because there's no way this mutex guard can be poisoned and |
| // because there's no way to recover, even if it is poisoned. |
| let set = self.device_unlocked_set.lock().unwrap(); |
| !set.contains(&user_id) |
| } |
| |
| /// Sets the device locked status for the user. This method is called externally. |
| pub fn set_device_locked(&self, user_id: i32, device_locked_status: bool) { |
| // unwrap here because there's no way this mutex guard can be poisoned and |
| // because there's no way to recover, even if it is poisoned. |
| let mut set = self.device_unlocked_set.lock().unwrap(); |
| if device_locked_status { |
| set.remove(&user_id); |
| } else { |
| set.insert(user_id); |
| } |
| } |
| |
| /// Add this auth token to the database. |
| /// Then present the auth token to the op auth map. If an operation is waiting for this |
| /// auth token this fulfills the request and removes the receiver from the map. |
| pub fn add_auth_token(&self, hat: HardwareAuthToken) { |
| DB.with(|db| db.borrow_mut().insert_auth_token(&hat)); |
| self.op_auth_map.add_auth_token(hat); |
| } |
| |
| /// This allows adding an entry to the op_auth_map, indexed by the operation challenge. |
| /// This is to be called by create_operation, once it has received the operation challenge |
| /// from keymint for an operation whose authorization decision is OpAuthRequired, as signalled |
| /// by the DeferredAuthState. |
| fn register_op_auth_receiver(&self, challenge: i64, recv: TokenReceiver) { |
| self.op_auth_map.add_receiver(challenge, recv); |
| } |
| |
| /// Given the set of key parameters and flags, check if super encryption is required. |
| pub fn super_encryption_required( |
| domain: &Domain, |
| key_parameters: &[KeyParameter], |
| flags: Option<i32>, |
| ) -> SuperEncryptionType { |
| if let Some(flags) = flags { |
| if (flags & KEY_FLAG_AUTH_BOUND_WITHOUT_CRYPTOGRAPHIC_LSKF_BINDING) != 0 { |
| return SuperEncryptionType::None; |
| } |
| } |
| // Each answer has a priority, numerically largest priority wins. |
| struct Candidate { |
| priority: u32, |
| enc_type: SuperEncryptionType, |
| } |
| let mut result = Candidate { priority: 0, enc_type: SuperEncryptionType::None }; |
| for kp in key_parameters { |
| let t = match kp.key_parameter_value() { |
| KeyParameterValue::MaxBootLevel(level) => { |
| Candidate { priority: 3, enc_type: SuperEncryptionType::BootLevel(*level) } |
| } |
| KeyParameterValue::UnlockedDeviceRequired if *domain == Domain::APP => { |
| Candidate { priority: 2, enc_type: SuperEncryptionType::ScreenLockBound } |
| } |
| KeyParameterValue::UserSecureID(_) if *domain == Domain::APP => { |
| Candidate { priority: 1, enc_type: SuperEncryptionType::LskfBound } |
| } |
| _ => Candidate { priority: 0, enc_type: SuperEncryptionType::None }, |
| }; |
| if t.priority > result.priority { |
| result = t; |
| } |
| } |
| result.enc_type |
| } |
| |
| /// Finds a matching auth token along with a timestamp token. |
| /// This method looks through auth-tokens cached by keystore which satisfy the given |
| /// authentication information (i.e. |secureUserId|). |
| /// The most recent matching auth token which has a |challenge| field which matches |
| /// the passed-in |challenge| parameter is returned. |
| /// In this case the |authTokenMaxAgeMillis| parameter is not used. |
| /// |
| /// Otherwise, the most recent matching auth token which is younger than |authTokenMaxAgeMillis| |
| /// is returned. |
| pub fn get_auth_tokens( |
| &self, |
| challenge: i64, |
| secure_user_id: i64, |
| auth_token_max_age_millis: i64, |
| ) -> Result<(HardwareAuthToken, TimeStampToken)> { |
| let auth_type = HardwareAuthenticatorType::ANY; |
| let sids: Vec<i64> = vec![secure_user_id]; |
| // Filter the matching auth tokens by challenge |
| let result = Self::find_auth_token(|hat: &AuthTokenEntry| { |
| (challenge == hat.challenge()) && hat.satisfies(&sids, auth_type) |
| }); |
| |
| let auth_token = if let Some((auth_token_entry, _)) = result { |
| auth_token_entry.take_auth_token() |
| } else { |
| // Filter the matching auth tokens by age. |
| if auth_token_max_age_millis != 0 { |
| let now_in_millis = MonotonicRawTime::now(); |
| let result = Self::find_auth_token(|auth_token_entry: &AuthTokenEntry| { |
| let token_valid = now_in_millis |
| .checked_sub(&auth_token_entry.time_received()) |
| .map_or(false, |token_age_in_millis| { |
| auth_token_max_age_millis > token_age_in_millis.milliseconds() |
| }); |
| token_valid && auth_token_entry.satisfies(&sids, auth_type) |
| }); |
| |
| if let Some((auth_token_entry, _)) = result { |
| auth_token_entry.take_auth_token() |
| } else { |
| return Err(AuthzError::Rc(AuthzResponseCode::NO_AUTH_TOKEN_FOUND)) |
| .context("In get_auth_tokens: No auth token found."); |
| } |
| } else { |
| return Err(AuthzError::Rc(AuthzResponseCode::NO_AUTH_TOKEN_FOUND)).context( |
| concat!( |
| "In get_auth_tokens: No auth token found for ", |
| "the given challenge and passed-in auth token max age is zero." |
| ), |
| ); |
| } |
| }; |
| // Wait and obtain the timestamp token from secure clock service. |
| let tst = get_timestamp_token(challenge) |
| .context("In get_auth_tokens. Error in getting timestamp token.")?; |
| Ok((auth_token, tst)) |
| } |
| } |
| |
| // TODO: Add tests to enforcement module (b/175578618). |