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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.cassandra.service;

import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import java.util.concurrent.atomic.AtomicLong;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.cassandra.auth.*;
import org.apache.cassandra.config.CFMetaData;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.config.Schema;
import org.apache.cassandra.config.SchemaConstants;
import org.apache.cassandra.cql3.QueryHandler;
import org.apache.cassandra.cql3.QueryProcessor;
import org.apache.cassandra.cql3.functions.Function;
import org.apache.cassandra.db.SystemKeyspace;
import org.apache.cassandra.exceptions.AuthenticationException;
import org.apache.cassandra.exceptions.InvalidRequestException;
import org.apache.cassandra.exceptions.UnauthorizedException;
import org.apache.cassandra.schema.SchemaKeyspace;
import org.apache.cassandra.thrift.ThriftValidation;
import org.apache.cassandra.utils.FBUtilities;
import org.apache.cassandra.utils.JVMStabilityInspector;
import org.apache.cassandra.utils.CassandraVersion;

/**
 * State related to a client connection.
 */
public class ClientState
{
    private static final Logger logger = LoggerFactory.getLogger(ClientState.class);
    public static final CassandraVersion DEFAULT_CQL_VERSION = org.apache.cassandra.cql3.QueryProcessor.CQL_VERSION;

    private static final Set READABLE_SYSTEM_RESOURCES = new HashSet<>();
    private static final Set PROTECTED_AUTH_RESOURCES = new HashSet<>();
    private static final Set DROPPABLE_SYSTEM_AUTH_TABLES = new HashSet<>();
    static
    {
        // We want these system cfs to be always readable to authenticated users since many tools rely on them
        // (nodetool, cqlsh, bulkloader, etc.)
        for (String cf : Arrays.asList(SystemKeyspace.LOCAL, SystemKeyspace.PEERS))
            READABLE_SYSTEM_RESOURCES.add(DataResource.table(SchemaConstants.SYSTEM_KEYSPACE_NAME, cf));

        SchemaKeyspace.ALL.forEach(table -> READABLE_SYSTEM_RESOURCES.add(DataResource.table(SchemaConstants.SCHEMA_KEYSPACE_NAME, table)));

        // neither clients nor tools need authentication/authorization
        if (DatabaseDescriptor.isDaemonInitialized())
        {
            PROTECTED_AUTH_RESOURCES.addAll(DatabaseDescriptor.getAuthenticator().protectedResources());
            PROTECTED_AUTH_RESOURCES.addAll(DatabaseDescriptor.getAuthorizer().protectedResources());
            PROTECTED_AUTH_RESOURCES.addAll(DatabaseDescriptor.getRoleManager().protectedResources());
        }

        DROPPABLE_SYSTEM_AUTH_TABLES.add(DataResource.table(SchemaConstants.AUTH_KEYSPACE_NAME, PasswordAuthenticator.LEGACY_CREDENTIALS_TABLE));
        DROPPABLE_SYSTEM_AUTH_TABLES.add(DataResource.table(SchemaConstants.AUTH_KEYSPACE_NAME, CassandraRoleManager.LEGACY_USERS_TABLE));
        DROPPABLE_SYSTEM_AUTH_TABLES.add(DataResource.table(SchemaConstants.AUTH_KEYSPACE_NAME, CassandraAuthorizer.USER_PERMISSIONS));
    }

    // Current user for the session
    private volatile AuthenticatedUser user;
    private volatile String keyspace;

    /**
     * Force Compact Tables to be represented as CQL ones for the current client session (simulates
     * ALTER .. DROP COMPACT STORAGE but only for this session)
     */
    private volatile boolean noCompactMode;

    private static final QueryHandler cqlQueryHandler;
    static
    {
        QueryHandler handler = QueryProcessor.instance;
        String customHandlerClass = System.getProperty("cassandra.custom_query_handler_class");
        if (customHandlerClass != null)
        {
            try
            {
                handler = FBUtilities.construct(customHandlerClass, "QueryHandler");
                logger.info("Using {} as query handler for native protocol queries (as requested with -Dcassandra.custom_query_handler_class)", customHandlerClass);
            }
            catch (Exception e)
            {
                JVMStabilityInspector.inspectThrowable(e);
                logger.info("Cannot use class {} as query handler ({}), ignoring by defaulting on normal query handling", customHandlerClass, e.getMessage());
            }
        }
        cqlQueryHandler = handler;
    }

    // isInternal is used to mark ClientState as used by some internal component
    // that should have an ability to modify system keyspace.
    public final boolean isInternal;

    // The remote address of the client - null for internal clients.
    private final InetSocketAddress remoteAddress;

    // The biggest timestamp that was returned by getTimestamp/assigned to a query. This is global to ensure that the
    // timestamp assigned are strictly monotonic on a node, which is likely what user expect intuitively (more likely,
    // most new user will intuitively expect timestamp to be strictly monotonic cluster-wise, but while that last part
    // is unrealistic expectation, doing it node-wise is easy).
    private static final AtomicLong lastTimestampMicros = new AtomicLong(0);

    /**
     * Construct a new, empty ClientState for internal calls.
     */
    private ClientState()
    {
        this.isInternal = true;
        this.remoteAddress = null;
    }

    protected ClientState(InetSocketAddress remoteAddress)
    {
        this.isInternal = false;
        this.remoteAddress = remoteAddress;
        if (!DatabaseDescriptor.getAuthenticator().requireAuthentication())
            this.user = AuthenticatedUser.ANONYMOUS_USER;
    }

    /**
     * @return a ClientState object for internal C* calls (not limited by any kind of auth).
     */
    public static ClientState forInternalCalls()
    {
        return new ClientState();
    }

    /**
     * @return a ClientState object for external clients (thrift/native protocol users).
     */
    public static ClientState forExternalCalls(SocketAddress remoteAddress)
    {
        return new ClientState((InetSocketAddress)remoteAddress);
    }

    /**
     * This clock guarantees that updates for the same ClientState will be ordered
     * in the sequence seen, even if multiple updates happen in the same millisecond.
     */
    public long getTimestamp()
    {
        while (true)
        {
            long current = System.currentTimeMillis() * 1000;
            long last = lastTimestampMicros.get();
            long tstamp = last >= current ? last + 1 : current;
            if (lastTimestampMicros.compareAndSet(last, tstamp))
                return tstamp;
        }
    }

    /**
     * Returns a timestamp suitable for paxos given the timestamp of the last known commit (or in progress update).
     * 

* Paxos ensures that the timestamp it uses for commits respects the serial order of those commits. It does so * by having each replica reject any proposal whose timestamp is not strictly greater than the last proposal it * accepted. So in practice, which timestamp we use for a given proposal doesn't affect correctness but it does * affect the chance of making progress (if we pick a timestamp lower than what has been proposed before, our * new proposal will just get rejected). *

* As during the prepared phase replica send us the last propose they accepted, a first option would be to take * the maximum of those last accepted proposal timestamp plus 1 (and use a default value, say 0, if it's the * first known proposal for the partition). This would most work (giving commits the timestamp 0, 1, 2, ... * in the order they are commited) up to 2 important caveats: * 1) it would give a very poor experience when Paxos and non-Paxos updates are mixed in the same partition, * since paxos operations wouldn't be using microseconds timestamps. And while you shouldn't theoretically * mix the 2 kind of operations, this would still be pretty unintuitive. And what if you started writing * normal updates and realize later you should switch to Paxos to enforce a property you want? * 2) this wouldn't actually be safe due to the expiration set on the Paxos state table. *

* So instead, we initially chose to use the current time in microseconds as for normal update. Which works in * general but mean that clock skew creates unavailability periods for Paxos updates (either a node has his clock * in the past and he may no be able to get commit accepted until its clock catch up, or a node has his clock in * the future and then once one of its commit his accepted, other nodes ones won't be until they catch up). This * is ok for small clock skew (few ms) but can be pretty bad for large one. *

* Hence our current solution: we mix both approaches. That is, we compare the timestamp of the last known * accepted proposal and the local time. If the local time is greater, we use it, thus keeping paxos timestamps * locked to the current time in general (making mixing Paxos and non-Paxos more friendly, and behaving correctly * when the paxos state expire (as long as your maximum clock skew is lower than the Paxos state expiration * time)). Otherwise (the local time is lower than the last proposal, meaning that this last proposal was done * with a clock in the future compared to the local one), we use the last proposal timestamp plus 1, ensuring * progress. * * @param minTimestampToUse the max timestamp of the last proposal accepted by replica having responded * to the prepare phase of the paxos round this is for. In practice, that's the minimum timestamp this method * may return. * @return a timestamp suitable for a Paxos proposal (using the reasoning described above). Note that * contrarily to the {@link #getTimestamp()} method, the return value is not guaranteed to be unique (nor * monotonic) across calls since it can return it's argument (so if the same argument is passed multiple times, * it may be returned multiple times). Note that we still ensure Paxos "ballot" are unique (for different * proposal) by (securely) randomizing the non-timestamp part of the UUID. */ public long getTimestampForPaxos(long minTimestampToUse) { while (true) { long current = Math.max(System.currentTimeMillis() * 1000, minTimestampToUse); long last = lastTimestampMicros.get(); long tstamp = last >= current ? last + 1 : current; // Note that if we ended up picking minTimestampMicrosToUse (it was "in the future"), we don't // want to change the local clock, otherwise a single node in the future could corrupt the clock // of all nodes and for all inserts (since non-paxos inserts also use lastTimestampMicros). // See CASSANDRA-11991 if (tstamp == minTimestampToUse || lastTimestampMicros.compareAndSet(last, tstamp)) return tstamp; } } public static QueryHandler getCQLQueryHandler() { return cqlQueryHandler; } public InetSocketAddress getRemoteAddress() { return remoteAddress; } public String getRawKeyspace() { return keyspace; } public String getKeyspace() throws InvalidRequestException { if (keyspace == null) throw new InvalidRequestException("No keyspace has been specified. USE a keyspace, or explicitly specify keyspace.tablename"); return keyspace; } public void setKeyspace(String ks) throws InvalidRequestException { // Skip keyspace validation for non-authenticated users. Apparently, some client libraries // call set_keyspace() before calling login(), and we have to handle that. if (user != null && Schema.instance.getKSMetaData(ks) == null) throw new InvalidRequestException("Keyspace '" + ks + "' does not exist"); keyspace = ks; } public void setNoCompactMode() { this.noCompactMode = true; } public boolean isNoCompactMode() { return noCompactMode; } /** * Attempts to login the given user. */ public void login(AuthenticatedUser user) throws AuthenticationException { // Login privilege is not inherited via granted roles, so just // verify that the role with the credentials that were actually // supplied has it if (user.isAnonymous() || DatabaseDescriptor.getRoleManager().canLogin(user.getPrimaryRole())) this.user = user; else throw new AuthenticationException(String.format("%s is not permitted to log in", user.getName())); } public void hasAllKeyspacesAccess(Permission perm) throws UnauthorizedException { if (isInternal) return; validateLogin(); ensureHasPermission(perm, DataResource.root()); } public void hasKeyspaceAccess(String keyspace, Permission perm) throws UnauthorizedException, InvalidRequestException { hasAccess(keyspace, perm, DataResource.keyspace(keyspace)); } public void hasColumnFamilyAccess(String keyspace, String columnFamily, Permission perm) throws UnauthorizedException, InvalidRequestException { ThriftValidation.validateColumnFamily(keyspace, columnFamily); hasAccess(keyspace, perm, DataResource.table(keyspace, columnFamily)); } public void hasColumnFamilyAccess(CFMetaData cfm, Permission perm) throws UnauthorizedException, InvalidRequestException { hasAccess(cfm.ksName, perm, cfm.resource); } private void hasAccess(String keyspace, Permission perm, DataResource resource) throws UnauthorizedException, InvalidRequestException { validateKeyspace(keyspace); if (isInternal) return; validateLogin(); preventSystemKSSchemaModification(keyspace, resource, perm); if ((perm == Permission.SELECT) && READABLE_SYSTEM_RESOURCES.contains(resource)) return; if (PROTECTED_AUTH_RESOURCES.contains(resource)) if ((perm == Permission.CREATE) || (perm == Permission.ALTER) || (perm == Permission.DROP)) throw new UnauthorizedException(String.format("%s schema is protected", resource)); ensureHasPermission(perm, resource); } public void ensureHasPermission(Permission perm, IResource resource) throws UnauthorizedException { if (!DatabaseDescriptor.getAuthorizer().requireAuthorization()) return; // Access to built in functions is unrestricted if(resource instanceof FunctionResource && resource.hasParent()) if (((FunctionResource)resource).getKeyspace().equals(SchemaConstants.SYSTEM_KEYSPACE_NAME)) return; checkPermissionOnResourceChain(perm, resource); } // Convenience method called from checkAccess method of CQLStatement // Also avoids needlessly creating lots of FunctionResource objects public void ensureHasPermission(Permission permission, Function function) { // Save creating a FunctionResource is we don't need to if (!DatabaseDescriptor.getAuthorizer().requireAuthorization()) return; // built in functions are always available to all if (function.isNative()) return; checkPermissionOnResourceChain(permission, FunctionResource.function(function.name().keyspace, function.name().name, function.argTypes())); } private void checkPermissionOnResourceChain(Permission perm, IResource resource) { for (IResource r : Resources.chain(resource)) if (authorize(r).contains(perm)) return; throw new UnauthorizedException(String.format("User %s has no %s permission on %s or any of its parents", user.getName(), perm, resource)); } private void preventSystemKSSchemaModification(String keyspace, DataResource resource, Permission perm) throws UnauthorizedException { // we only care about DDL statements if (perm != Permission.ALTER && perm != Permission.DROP && perm != Permission.CREATE) return; // prevent ALL local system keyspace modification if (SchemaConstants.isLocalSystemKeyspace(keyspace)) throw new UnauthorizedException(keyspace + " keyspace is not user-modifiable."); if (SchemaConstants.isReplicatedSystemKeyspace(keyspace)) { // allow users with sufficient privileges to alter replication params of replicated system keyspaces if (perm == Permission.ALTER && resource.isKeyspaceLevel()) return; // allow users with sufficient privileges to drop legacy tables in replicated system keyspaces if (perm == Permission.DROP && DROPPABLE_SYSTEM_AUTH_TABLES.contains(resource)) return; // prevent all other modifications of replicated system keyspaces throw new UnauthorizedException(String.format("Cannot %s %s", perm, resource)); } } public void validateLogin() throws UnauthorizedException { if (user == null) throw new UnauthorizedException("You have not logged in"); } public void ensureNotAnonymous() throws UnauthorizedException { validateLogin(); if (user.isAnonymous()) throw new UnauthorizedException("You have to be logged in and not anonymous to perform this request"); } public void ensureIsSuper(String message) throws UnauthorizedException { if (DatabaseDescriptor.getAuthenticator().requireAuthentication() && (user == null || !user.isSuper())) throw new UnauthorizedException(message); } private static void validateKeyspace(String keyspace) throws InvalidRequestException { if (keyspace == null) throw new InvalidRequestException("You have not set a keyspace for this session"); } public AuthenticatedUser getUser() { return user; } public static CassandraVersion[] getCQLSupportedVersion() { return new CassandraVersion[]{ QueryProcessor.CQL_VERSION }; } private Set authorize(IResource resource) { return user.getPermissions(resource); } }





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