// Copyright (C) 2008 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.google.gerrit.sshd;
import com.google.gerrit.reviewdb.AccountSshKey;
import com.google.gerrit.server.AccessPath;
import com.google.gerrit.server.CurrentUser;
import com.google.gerrit.server.IdentifiedUser;
import com.google.gerrit.server.PeerDaemonUser;
import com.google.gerrit.server.config.SitePaths;
import com.google.gerrit.sshd.SshScope.Context;
import com.google.inject.Inject;
import com.google.inject.Provider;
import com.google.inject.Singleton;
import org.apache.commons.codec.binary.Base64;
import org.apache.mina.core.future.IoFuture;
import org.apache.mina.core.future.IoFutureListener;
import org.apache.sshd.common.KeyPairProvider;
import org.apache.sshd.common.SshException;
import org.apache.sshd.common.util.Buffer;
import org.apache.sshd.server.PublickeyAuthenticator;
import org.apache.sshd.server.session.ServerSession;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.net.SocketAddress;
import java.security.KeyPair;
import java.security.PublicKey;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
/**
* Authenticates by public key through {@link AccountSshKey} entities.
*/
@Singleton
class DatabasePubKeyAuth implements PublickeyAuthenticator {
private static final Logger log =
LoggerFactory.getLogger(DatabasePubKeyAuth.class);
private final SshKeyCacheImpl sshKeyCache;
private final SshLog sshLog;
private final IdentifiedUser.GenericFactory userFactory;
private final PeerDaemonUser.Factory peerFactory;
private final Set<PublicKey> myHostKeys;
private volatile PeerKeyCache peerKeyCache;
@Inject
DatabasePubKeyAuth(final SshKeyCacheImpl skc, final SshLog l,
final IdentifiedUser.GenericFactory uf, final PeerDaemonUser.Factory pf,
final SitePaths site, final KeyPairProvider hostKeyProvider) {
sshKeyCache = skc;
sshLog = l;
userFactory = uf;
peerFactory = pf;
myHostKeys = myHostKeys(hostKeyProvider);
peerKeyCache = new PeerKeyCache(site.peer_keys);
}
private static Set<PublicKey> myHostKeys(KeyPairProvider p) {
final Set<PublicKey> keys = new HashSet<PublicKey>(2);
addPublicKey(keys, p, KeyPairProvider.SSH_RSA);
addPublicKey(keys, p, KeyPairProvider.SSH_DSS);
return keys;
}
private static void addPublicKey(final Collection<PublicKey> out,
final KeyPairProvider p, final String type) {
final KeyPair pair = p.loadKey(type);
if (pair != null && pair.getPublic() != null) {
out.add(pair.getPublic());
}
}
public boolean authenticate(final String username,
final PublicKey suppliedKey, final ServerSession session) {
final SshSession sd = session.getAttribute(SshSession.KEY);
if (PeerDaemonUser.USER_NAME.equals(username)) {
if (myHostKeys.contains(suppliedKey)
|| getPeerKeys().contains(suppliedKey)) {
PeerDaemonUser user = peerFactory.create(sd.getRemoteAddress());
return success(username, session, sd, user);
} else {
sd.authenticationError(username, "no-matching-key");
return false;
}
}
final Iterable<SshKeyCacheEntry> keyList = sshKeyCache.get(username);
final SshKeyCacheEntry key = find(keyList, suppliedKey);
if (key == null) {
final String err;
if (keyList == SshKeyCacheImpl.NO_SUCH_USER) {
err = "user-not-found";
} else if (keyList == SshKeyCacheImpl.NO_KEYS) {
err = "key-list-empty";
} else {
err = "no-matching-key";
}
sd.authenticationError(username, err);
return false;
}
// Double check that all of the keys are for the same user account.
// This should have been true when the cache factory method loaded
// the list into memory, but we want to be extra paranoid about our
// security check to ensure there aren't two users sharing the same
// user name on the server.
//
for (final SshKeyCacheEntry otherKey : keyList) {
if (!key.getAccount().equals(otherKey.getAccount())) {
sd.authenticationError(username, "keys-cross-accounts");
return false;
}
}
if (!createUser(sd, key).getAccount().isActive()) {
sd.authenticationError(username, "inactive-account");
return false;
}
return success(username, session, sd, createUser(sd, key));
}
private Set<PublicKey> getPeerKeys() {
PeerKeyCache p = peerKeyCache;
if (!p.isCurrent()) {
p = p.reload();
peerKeyCache = p;
}
return p.keys;
}
private boolean success(final String username, final ServerSession session,
final SshSession sd, final CurrentUser user) {
if (sd.getCurrentUser() == null) {
sd.authenticationSuccess(username, user);
// If this is the first time we've authenticated this
// session, record a login event in the log and add
// a close listener to record a logout event.
//
Context ctx = new Context(sd, null);
Context old = SshScope.set(ctx);
try {
sshLog.onLogin();
} finally {
SshScope.set(old);
}
session.getIoSession().getCloseFuture().addListener(
new IoFutureListener<IoFuture>() {
@Override
public void operationComplete(IoFuture future) {
final Context ctx = new Context(sd, null);
final Context old = SshScope.set(ctx);
try {
sshLog.onLogout();
} finally {
SshScope.set(old);
}
}
});
}
return true;
}
private IdentifiedUser createUser(final SshSession sd,
final SshKeyCacheEntry key) {
return userFactory.create(AccessPath.SSH_COMMAND,
new Provider<SocketAddress>() {
@Override
public SocketAddress get() {
return sd.getRemoteAddress();
}
}, key.getAccount());
}
private SshKeyCacheEntry find(final Iterable<SshKeyCacheEntry> keyList,
final PublicKey suppliedKey) {
for (final SshKeyCacheEntry k : keyList) {
if (k.match(suppliedKey)) {
return k;
}
}
return null;
}
private static class PeerKeyCache {
private final File path;
private final long modified;
final Set<PublicKey> keys;
PeerKeyCache(final File path) {
this.path = path;
this.modified = path.lastModified();
this.keys = read(path);
}
private static Set<PublicKey> read(File path) {
try {
final BufferedReader br = new BufferedReader(new FileReader(path));
try {
final Set<PublicKey> keys = new HashSet<PublicKey>();
String line;
while ((line = br.readLine()) != null) {
line = line.trim();
if (line.startsWith("#") || line.isEmpty()) {
continue;
}
try {
byte[] bin = Base64.decodeBase64(line.getBytes("ISO-8859-1"));
keys.add(new Buffer(bin).getRawPublicKey());
} catch (RuntimeException e) {
logBadKey(path, line, e);
} catch (SshException e) {
logBadKey(path, line, e);
}
}
return Collections.unmodifiableSet(keys);
} finally {
br.close();
}
} catch (FileNotFoundException noFile) {
return Collections.emptySet();
} catch (IOException err) {
log.error("Cannot read " + path, err);
return Collections.emptySet();
}
}
private static void logBadKey(File path, String line, Exception e) {
log.warn("Invalid key in " + path + ":\n " + line, e);
}
boolean isCurrent() {
return path.lastModified() == modified;
}
PeerKeyCache reload() {
return new PeerKeyCache(path);
}
}
}