/*
* 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.sshd.client.keyverifier;
import java.io.File;
import java.io.IOException;
import java.nio.file.LinkOption;
import java.nio.file.Path;
import java.security.GeneralSecurityException;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
import org.apache.sshd.client.config.hosts.KnownHostEntry;
import org.apache.sshd.common.util.Pair;
import org.apache.sshd.common.util.io.IoUtils;
/**
* Monitors the {@code ~/.ssh/known_hosts} file of the user currently running
* the client, updating and re-loading it if necessary. It also (optionally)
* enforces the same permissions regime as {@code OpenSSH}.
*
* @author <a href="mailto:dev@mina.apache.org">Apache MINA SSHD Project</a>
*/
public class DefaultKnownHostsServerKeyVerifier extends KnownHostsServerKeyVerifier {
private final boolean strict;
public DefaultKnownHostsServerKeyVerifier(ServerKeyVerifier delegate) {
this(delegate, true);
}
public DefaultKnownHostsServerKeyVerifier(ServerKeyVerifier delegate, boolean strict) {
this(delegate, strict, KnownHostEntry.getDefaultKnownHostsFile(), IoUtils.getLinkOptions(false));
}
public DefaultKnownHostsServerKeyVerifier(ServerKeyVerifier delegate, boolean strict, File file) {
this(delegate, strict, Objects.requireNonNull(file, "No file provided").toPath(), IoUtils.getLinkOptions(false));
}
public DefaultKnownHostsServerKeyVerifier(ServerKeyVerifier delegate, boolean strict, Path file, LinkOption... options) {
super(delegate, file, options);
this.strict = strict;
}
/**
* @return If {@code true} then makes sure that the containing folder
* has 0700 access and the file 0644. <B>Note:</B> for <I>Windows</I> it
* does not check these permissions
* @see #validateStrictConfigFilePermissions(Path, LinkOption...)
*/
public final boolean isStrict() {
return strict;
}
@Override
protected List<HostEntryPair> reloadKnownHosts(Path file) throws IOException, GeneralSecurityException {
if (isStrict()) {
if (log.isDebugEnabled()) {
log.debug("reloadKnownHosts({}) check permissions", file);
}
Pair<String, Object> violation = validateStrictConfigFilePermissions(file);
if (violation != null) {
log.warn("reloadKnownHosts({}) invalid file permissions: {}", file, violation.getFirst());
updateReloadAttributes();
return Collections.emptyList();
}
}
return super.reloadKnownHosts(file);
}
}