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Commit c23be504 authored by Atneya Nair's avatar Atneya Nair
Browse files

Add permission caching to PermissionController 

Audioserver currently calls upwards to system_server for all permission
checks.

Invert the call direction, and maintain mapping of uids which hold a
particular permission. Add AIDL interface for system_server and enum
representing relevant permissions.

Test: atest audiopermissioncontroller_test
Bug: 338089555
Flag: com.android.media.audio.audioserver_permissions
Change-Id: I45be63217fa58544e6dd9530a5d9e29b99f31ade
parent 85a07e23

aidl/com/android/media/permission/INativePermissionController.aidl

+10 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 


package com.android.media.permission;



import com.android.media.permission.PermissionEnum;

import com.android.media.permission.UidPackageState;



/**
@@ -33,4 +34,13 @@ interface INativePermissionController { 
     * If the list is empty, the package no longer exists.

     */

    void updatePackagesForUid(in UidPackageState newPackageState);

    /**

     * Populate or replace the list of uids which holds a particular permission.

     * Runtime permissions will need additional checks, and should not use the cache as-is.

     * Not virtual device aware.

     * Is is possible for updates to the permission state to be delayed during high traffic.

     * @param perm - Enum representing the permission for which holders are being supplied

     * @param uids - Uids (not app-ids) which hold the permission. Should be sorted

     */

    void populatePermissionState(in PermissionEnum perm, in int[] uids);

}

aidl/com/android/media/permission/PermissionEnum.aidl

0 → 100644
+31 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2024 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.

 */



package com.android.media.permission;



/**

 * Enumerates permissions which are tracked/pushed by NativePermissionController

 * {@hide}

 */

enum PermissionEnum {

    MODIFY_AUDIO_ROUTING = 0,

    MODIFY_PHONE_STATE = 1,

    CALL_AUDIO_INTERCEPTION = 2,

    // This is a runtime + WIU permission, which means data delivery should be protected by AppOps

    // We query the controller only for early fails/hard errors

    RECORD_AUDIO = 3,

    ENUM_SIZE = 4, // Not for actual usage

}

services/audiopolicy/permission/NativePermissionController.cpp

+24 −0
Original line number Diff line number Diff line
@@ -88,6 +88,19 @@ Status NativePermissionController::updatePackagesForUid(const UidPackageState& n 
    return Status::ok();

}



Status NativePermissionController::populatePermissionState(PermissionEnum perm,

                                                           const std::vector<int>& uids) {

    if (perm >= PermissionEnum::ENUM_SIZE || static_cast<int>(perm) < 0) {

        return Status::fromExceptionCode(Status::EX_ILLEGAL_ARGUMENT);

    }

    std::lock_guard l{m_};

    auto& cursor = permission_map_[static_cast<size_t>(perm)];

    cursor = std::vector<uid_t>{uids.begin(), uids.end()};

    // should be sorted

    std::sort(cursor.begin(), cursor.end());

    return Status::ok();

}



// -- End Binder methods



Result<std::vector<std::string>> NativePermissionController::getPackagesForUid(uid_t uid) const {
@@ -120,4 +133,15 @@ Result<bool> NativePermissionController::validateUidPackagePair( 
           (std::find(cursor->second.begin(), cursor->second.end(), packageName) !=

            cursor->second.end());

}



Result<bool> NativePermissionController::checkPermission(PermissionEnum perm, uid_t uid) const {

    std::lock_guard l{m_};

    const auto& uids = permission_map_[static_cast<size_t>(perm)];

    if (!uids.empty()) {

        return std::binary_search(uids.begin(), uids.end(), uid);

    } else {

        return unexpected{::android::NO_INIT};

    }

}



}  // namespace com::android::media::permission

services/audiopolicy/permission/include/media/IPermissionProvider.h

+6 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#include <optional>

#include <vector>



#include <com/android/media/permission/PermissionEnum.h>

#include <error/Result.h>



namespace com::android::media::permission {
@@ -38,6 +39,11 @@ class IPermissionProvider { 
    // Fails if the provider does not know about the app-id.

    virtual ::android::error::Result<bool> validateUidPackagePair(

            uid_t uid, const std::string& packageName) const = 0;



    // True iff the uid holds the permission (user aware).

    // Fails with NO_INIT if cache hasn't been populated.

    virtual ::android::error::Result<bool> checkPermission(PermissionEnum permission,

                                                           uid_t uid) const = 0;

    virtual ~IPermissionProvider() = default;

};

}  // namespace com::android::media::permission

services/audiopolicy/permission/include/media/NativePermissionController.h

+6 −0
Original line number Diff line number Diff line
@@ -33,16 +33,22 @@ class NativePermissionController : public BnNativePermissionController, public I 
  public:

    Status populatePackagesForUids(const std::vector<UidPackageState>& initialPackageStates) final;

    Status updatePackagesForUid(const UidPackageState& newPackageState) final;

    Status populatePermissionState(PermissionEnum permission, const std::vector<int>& uids) final;

    // end binder methods



    ::android::error::Result<std::vector<std::string>> getPackagesForUid(uid_t uid) const final;

    ::android::error::Result<bool> validateUidPackagePair(

            uid_t uid, const std::string& packageName) const final;

    ::android::error::Result<bool> checkPermission(PermissionEnum permission,

                                                   uid_t uid) const final;



  private:

    mutable std::mutex m_;

    // map of app_ids to the set of packages names which could run in them (should be 1)

    std::unordered_map<uid_t, std::vector<std::string>> package_map_ GUARDED_BY(m_);

    bool is_package_populated_ GUARDED_BY(m_);

    // (logical) map of PermissionEnum to list of uids (not appid) which hold the perm

    std::array<std::vector<uid_t>, static_cast<size_t>(PermissionEnum::ENUM_SIZE)> permission_map_

            GUARDED_BY(m_);

};

}  // namespace com::android::media::permission