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Commit 3d8400f5 authored by Pavel Grafov's avatar Pavel Grafov
Browse files

Ensure policy has no absurdly long strings 

The following APIs now enforce limits and throw IllegalArgumentException
when limits are violated:
* DPM.setTrustAgentConfiguration() limits agent packgage name,
  component name, and strings within configuration bundle.
* DPM.setPermittedAccessibilityServices() limits package names.
* DPM.setPermittedInputMethods() limits package names.
* DPM.setAccountManagementDisabled() limits account name.
* DPM.setLockTaskPackages() limits package names.
* DPM.setAffiliationIds() limits id.
* DPM.transferOwnership() limits strings inside the bundle.

Package names are limited at 223, because they become directory names
and it is a filesystem restriction, see FrameworkParsingPackageUtils.

All other strings are limited at 65535, because longer ones break binary
XML serializer.

The following APIs silently truncate strings that are long beyond reason:
* DPM.setShortSupportMessage() truncates message at 200.
* DPM.setLongSupportMessage() truncates message at 20000.
* DPM.setOrganizationName() truncates org name at 200.

Bug: 260729089
Test: btest a.d.c.KeyguardTest
Test: btest a.d.c.SupportMessageTest
Test: btest a.d.c.PermitInputMethodsTest
Test: btest a.d.c.AccountManagementTest
Test: btest a.d.c.AffiliationIdsTest
Test: atest com.android.server.devicepolicy
Change-Id: Idcf54e408722f164d16bf2f24a00cd1f5b626d23
parent 1e9f13da

core/java/android/app/admin/DevicePolicyManager.java

+6 −6
Original line number Diff line number Diff line
@@ -13401,11 +13401,10 @@ public class DevicePolicyManager { 
    /**

     * Called by a device admin or holder of the permission

     * {@link android.Manifest.permission#MANAGE_DEVICE_POLICY_SUPPORT_MESSAGE} to set the short

     * support message. This will be displayed to the user

     * in settings screens where funtionality has been disabled by the admin. The message should be

     * limited to a short statement such as "This setting is disabled by your administrator. Contact

     * someone@example.com for support." If the message is longer than 200 characters it may be

     * truncated.

     * support message. This will be displayed to the user in settings screens where functionality

     * has been disabled by the admin. The message should be limited to a short statement such as

     * "This setting is disabled by your administrator. Contact someone@example.com for support."

     * If the message is longer than 200 characters it may be truncated.

     * <p>

     * If the short support message needs to be localized, it is the responsibility of the

     * {@link DeviceAdminReceiver} to listen to the {@link Intent#ACTION_LOCALE_CHANGED} broadcast
@@ -13460,7 +13459,8 @@ public class DevicePolicyManager { 














    /**















     * Called by a device admin to set the long support message. This will be displayed to the user













     * in the device administators settings screen.













     * in the device administrators settings screen. If the message is longer than 20000 characters













     * it may be truncated.















     * <p>















     * If the long support message needs to be localized, it is the responsibility of the















     * {@link DeviceAdminReceiver} to listen to the {@link Intent#ACTION_LOCALE_CHANGED} broadcast

























services/devicepolicy/java/com/android/server/devicepolicy/DevicePolicyManagerService.java



+94
−6




























Original line number
Diff line number
Diff line








@@ -39,7 +39,6 @@ import static android.Manifest.permission.MANAGE_DEVICE_POLICY_DEFAULT_SMS;













import static android.Manifest.permission.MANAGE_DEVICE_POLICY_DISPLAY;















import static android.Manifest.permission.MANAGE_DEVICE_POLICY_FACTORY_RESET;















import static android.Manifest.permission.MANAGE_DEVICE_POLICY_FUN;













import static android.Manifest.permission.MANAGE_DEVICE_POLICY_INPUT_METHODS;















import static android.Manifest.permission.MANAGE_DEVICE_POLICY_INSTALL_UNKNOWN_SOURCES;















import static android.Manifest.permission.MANAGE_DEVICE_POLICY_KEYGUARD;















import static android.Manifest.permission.MANAGE_DEVICE_POLICY_LOCALE;










@@ -520,6 +519,7 @@ import java.security.cert.CertificateFactory;













import java.security.cert.X509Certificate;















import java.text.DateFormat;















import java.time.LocalDate;













import java.util.ArrayDeque;















import java.util.ArrayList;















import java.util.Arrays;















import java.util.Collection;









@@ -532,6 +532,7 @@ import java.util.List;













import java.util.Locale;















import java.util.Map;















import java.util.Objects;













import java.util.Queue;















import java.util.Set;















import java.util.concurrent.CompletableFuture;















import java.util.concurrent.ExecutionException;










@@ -567,7 +568,15 @@ public class DevicePolicyManagerService extends IDevicePolicyManager.Stub {



























    private static final int REQUEST_PROFILE_OFF_DEADLINE = 5572;



























    // Binary XML serializer doesn't support longer strings













    private static final int MAX_POLICY_STRING_LENGTH = 65535;













    // FrameworkParsingPackageUtils#MAX_FILE_NAME_SIZE, Android packages are used in dir names.













    private static final int MAX_PACKAGE_NAME_LENGTH = 223;



























    private static final int MAX_PROFILE_NAME_LENGTH = 200;













    private static final int MAX_LONG_SUPPORT_MESSAGE_LENGTH = 20000;













    private static final int MAX_SHORT_SUPPORT_MESSAGE_LENGTH = 200;













    private static final int MAX_ORG_NAME_LENGTH = 200;





























    private static final long MS_PER_DAY = TimeUnit.DAYS.toMillis(1);
























@@ -11729,7 +11738,15 @@ public class DevicePolicyManagerService extends IDevicePolicyManager.Stub {













        }





























        Objects.requireNonNull(agent, "agent is null");













        int userHandle = UserHandle.getCallingUserId();

























        enforceMaxPackageNameLength(agent.getPackageName());













        final String agentAsString = agent.flattenToString();













        enforceMaxStringLength(agentAsString, "agent name");













        if (args != null) {













            enforceMaxStringLength(args, "args");













        }

























        int userHandle = mInjector.userHandleGetCallingUserId();















        synchronized (getLockObject()) {















            ActiveAdmin ap;















            if (isPermissionCheckFlagEnabled()) {









@@ -11746,7 +11763,7 @@ public class DevicePolicyManagerService extends IDevicePolicyManager.Stub {













            checkCanExecuteOrThrowUnsafe(















                    DevicePolicyManager.OPERATION_SET_TRUST_AGENT_CONFIGURATION);



























            ap.trustAgentInfos.put(agent.flattenToString(), new TrustAgentInfo(args));













            ap.trustAgentInfos.put(agentAsString, new TrustAgentInfo(args));















            saveSettingsLocked(userHandle);















        }















    }










@@ -12016,6 +12033,10 @@ public class DevicePolicyManagerService extends IDevicePolicyManager.Stub {













                isDeviceOwner(caller) || isProfileOwner(caller));





























        if (packageList != null) {













            for (String pkg : packageList) {













                enforceMaxPackageNameLength(pkg);













            }



























            int userId = caller.getUserId();















            final List<AccessibilityServiceInfo> enabledServices;















            long id = mInjector.binderClearCallingIdentity();










@@ -12197,6 +12218,10 @@ public class DevicePolicyManagerService extends IDevicePolicyManager.Stub {













        }





























        if (packageList != null) {













            for (String pkg : packageList) {













                enforceMaxPackageNameLength(pkg);













            }



























            List<InputMethodInfo> enabledImes = mInjector.binderWithCleanCallingIdentity(() ->















                    InputMethodManagerInternal.get().getEnabledInputMethodListAsUser(userId));















            if (enabledImes != null) {










@@ -14081,6 +14106,9 @@ public class DevicePolicyManagerService extends IDevicePolicyManager.Stub {













        if (!mHasFeature) {















            return;















        }

























        enforceMaxStringLength(accountType, "account type");



























        CallerIdentity caller;















        if (isPolicyEngineForFinanceFlagEnabled()) {















            caller = getCallerIdentity(who, callerPackageName);










@@ -14771,6 +14799,10 @@ public class DevicePolicyManagerService extends IDevicePolicyManager.Stub {













    public void setLockTaskPackages(ComponentName who, String callerPackageName, String[] packages)















            throws SecurityException {















        Objects.requireNonNull(packages, "packages is null");













        for (String pkg : packages) {













            enforceMaxPackageNameLength(pkg);













        }



























        CallerIdentity caller;















        if (isPolicyEngineForFinanceFlagEnabled()) {















            caller = getCallerIdentity(who, callerPackageName);










@@ -17373,6 +17405,8 @@ public class DevicePolicyManagerService extends IDevicePolicyManager.Stub {













        CallerIdentity caller;















        ActiveAdmin admin;



























        message = truncateIfLonger(message, MAX_SHORT_SUPPORT_MESSAGE_LENGTH);



























        if (isPermissionCheckFlagEnabled()) {















            caller = getCallerIdentity(who, callerPackageName);















            EnforcingAdmin enforcingAdmin = enforcePermissionAndGetEnforcingAdmin(










@@ -17433,6 +17467,9 @@ public class DevicePolicyManagerService extends IDevicePolicyManager.Stub {













        if (!mHasFeature) {















            return;















        }

























        message = truncateIfLonger(message, MAX_LONG_SUPPORT_MESSAGE_LENGTH);



























        Objects.requireNonNull(who, "ComponentName is null");















        final CallerIdentity caller = getCallerIdentity(who);















        synchronized (getLockObject()) {










@@ -17597,6 +17634,8 @@ public class DevicePolicyManagerService extends IDevicePolicyManager.Stub {













            Preconditions.checkCallAuthorization(isDeviceOwner(caller) || isProfileOwner(caller));















        }



























        text = truncateIfLonger(text, MAX_ORG_NAME_LENGTH);



























        synchronized (getLockObject()) {















            if (!isPermissionCheckFlagEnabled()) {















                admin = getProfileOwnerOrDeviceOwnerLocked(caller.getUserId());










@@ -17877,9 +17916,8 @@ public class DevicePolicyManagerService extends IDevicePolicyManager.Stub {













            throw new IllegalArgumentException("ids must not be null");















        }















        for (String id : ids) {













            if (TextUtils.isEmpty(id)) {













                throw new IllegalArgumentException("ids must not contain empty string");













            }













            Preconditions.checkArgument(!TextUtils.isEmpty(id), "ids must not have empty string");













            enforceMaxStringLength(id, "affiliation id");















        }





























        final Set<String> affiliationIds = new ArraySet<>(ids);










@@ -19392,6 +19430,9 @@ public class DevicePolicyManagerService extends IDevicePolicyManager.Stub {













                "Provided administrator and target are the same object.");















        Preconditions.checkArgument(!admin.getPackageName().equals(target.getPackageName()),















                "Provided administrator and target have the same package name.");













        if (bundle != null) {













            enforceMaxStringLength(bundle, "bundle");













        }





























        final CallerIdentity caller = getCallerIdentity(admin);















        Preconditions.checkCallAuthorization(










@@ -24091,6 +24132,53 @@ public class DevicePolicyManagerService extends IDevicePolicyManager.Stub {













        });















    }



























    /**













     * Truncates char sequence to maximum length, nulls are ignored.













     */













    private static CharSequence truncateIfLonger(CharSequence input, int maxLength) {













        return input == null || input.length() <= maxLength













                ? input













                : input.subSequence(0, maxLength);













    }

























    /**













     * Throw if string argument is too long to be serialized.













     */













    private static void enforceMaxStringLength(String str, String argName) {













        Preconditions.checkArgument(













                str.length() <= MAX_POLICY_STRING_LENGTH, argName + " loo long");













    }

























    private static void enforceMaxPackageNameLength(String pkg) {













        Preconditions.checkArgument(













                pkg.length() <= MAX_PACKAGE_NAME_LENGTH, "Package name too long");













    }

























    /**













     * Throw if persistable bundle contains any string that we can't serialize.













     */













    private static void enforceMaxStringLength(PersistableBundle bundle, String argName) {













        // Persistable bundles can have other persistable bundles as values, traverse with a queue.













        Queue<PersistableBundle> queue = new ArrayDeque<>();













        queue.add(bundle);













        while (!queue.isEmpty()) {













            PersistableBundle current = queue.remove();













            for (String key : current.keySet()) {













                enforceMaxStringLength(key, "key in " + argName);













                Object value = current.get(key);













                if (value instanceof String) {













                    enforceMaxStringLength((String) value, "string value in " + argName);













                } else if (value instanceof String[]) {













                    for (String str : (String[]) value) {













                        enforceMaxStringLength(str, "string value in " + argName);













                    }













                } else if (value instanceof PersistableBundle) {













                    queue.add((PersistableBundle) value);













                }













            }













        }













    }



























    private ActiveAdmin getActiveAdminForCaller(@Nullable ComponentName who,















            CallerIdentity caller) {















        synchronized (getLockObject()) {

























services/tests/servicestests/src/com/android/server/devicepolicy/DevicePolicyManagerTest.java



+41
−0




























Original line number
Diff line number
Diff line








@@ -130,6 +130,7 @@ import android.os.Build;













import android.os.Build.VERSION_CODES;















import android.os.Bundle;















import android.os.IpcDataCache;













import android.os.PersistableBundle;















import android.os.Process;















import android.os.UserHandle;















import android.os.UserManager;










@@ -8539,6 +8540,46 @@ public class DevicePolicyManagerTest extends DpmTestBase {













                eq(FUSED_PROVIDER), any(), eq(getServices().executor), any());















    }





























    /**













     * Verifies that bundles with tons of moderately long strings are persisted correctly.













     *













     * Policy is serialized into binary XML and there is a limit on the max string length: 65535.













     * This test ensures that as long as each string in the trust agent configuration is below this













     * limit, the policy can be serialized and deserialized correctly, even when the total length













     * of the configuration is above that limit. This should be the case because PersistableBundle













     * contents are stored as XML subtrees rather than as strings.













     */













    @Test













    public void testSetTrustAgentConfiguration_largeBundlePersisted() {













        setAsProfileOwner(admin1);



























        ComponentName agent = new ComponentName("some.trust.agent", "some.trust.agent.Agent");













        PersistableBundle configIn = new PersistableBundle();













        String kilobyteString = new String(new char[1024]).replace('\0', 'A');













        for (int i = 0; i < 1024; i++) {













            configIn.putString("key-" + i, kilobyteString);













        }



























        runAsCaller(mAdmin1Context, dpms, dpm -> {













            dpm.setTrustAgentConfiguration(admin1, agent, configIn);













        });



























        // Re-read policies to see if they were serialized/deserialized correctly.













        initializeDpms();



























        List<PersistableBundle> configsOut = new ArrayList<>();













        runAsCaller(mAdmin1Context, dpms, dpm -> {













            configsOut.addAll(dpm.getTrustAgentConfiguration(admin1, agent));













        });



























        assertThat(configsOut.size()).isEqualTo(1);













        PersistableBundle configOut = configsOut.get(0);













        assertThat(configOut.size()).isEqualTo(1024);













        for (int i = 0; i < 1024; i++) {













            assertThat(configOut.getString("key-" + i, null)).isEqualTo(kilobyteString);













        }













    }





























    private void setupVpnAuthorization(String userVpnPackage, int userVpnUid) {















        final AppOpsManager.PackageOps vpnOp = new AppOpsManager.PackageOps(userVpnPackage,















                userVpnUid, List.of(new AppOpsManager.OpEntry(