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lgoldstein pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/mina-sshd.git
commit 6eb232f3a0b92749fad3c314d47d78a61a85b401
Author: Lyor Goldstein <lgoldst...@apache.org>
AuthorDate: Mon Sep 23 09:41:46 2019 +0300
[SSHD-941] Allow user to override min./max. key sizes for a specific
session Diffi-Helman group exchange via session properties
---
CHANGES.md | 10 +++++++++-
.../main/java/org/apache/sshd/client/kex/DHGClient.java | 11 ++++++++---
.../main/java/org/apache/sshd/client/kex/DHGEXClient.java | 13 +++++++++++++
.../main/java/org/apache/sshd/server/kex/DHGEXServer.java | 15 ++++++++++-----
.../main/java/org/apache/sshd/server/kex/DHGServer.java | 3 ++-
5 files changed, 42 insertions(+), 10 deletions(-)
diff --git a/CHANGES.md b/CHANGES.md
index 70c4c90..2ec72a5 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -43,6 +43,10 @@ initialized in the past.
* The internal moduli used in Diffie-Hellman group exchange are **cached** -
lazy-loaded the 1st time such an exchange
occurs. The cache can be invalidated (and thus force a re-load) by invoking
`Moduli#clearInternalModuliCache`.
+* `DHGEXClient#init` implementation allows overriding the min./max. key sizes
for a specific session Diffi-Helman group
+exchange via properties - see `DHGEXClient#PROP_DHGEX_CLIENT_MIN/MAX_KEY`.
Similar applies for `DHGEXServer` but only for
+the message type=30.
+
## Behavioral changes and enhancements
* [SSHD-926](https://issues.apache.org/jira/browse/SSHD-930) - Add support for
OpenSSH 'lsets...@openssh.com' SFTP protocol extension.
@@ -50,8 +54,12 @@ occurs. The cache can be invalidated (and thus force a
re-load) by invoking `Mod
* [SSHD-930](https://issues.apache.org/jira/browse/SSHD-930) - Added
configuration allowing the user to specify whether client should wait
for the server's identification before sending its own.
-* [SSHD-931](https://issues.apache.org/jira/browse/SSHD-931) - Using an
executor supplier instead of a specific instance in `SftpSubsystemFactory`
+* [SSHD-931](https://issues.apache.org/jira/browse/SSHD-931) - Using an
executor supplier instead of a specific instance in `SftpSubsystemFactory`.
* [SSHD-934](https://issues.apache.org/jira/browse/SSHD-934) - Fixed ECDSA
public key encoding into OpenSSH format.
* [SSHD-937](https://issues.apache.org/jira/browse/SSHD-937) - Provide session
instance when creating a subsystem, user authentication, channel.
+
+* [SSHD-941](https://issues.apache.org/jira/browse/SSHD-941) - Allow user to
override min./max. key sizes for a specific session Diffi-Helman group
+exchange via properties.
+
diff --git a/sshd-core/src/main/java/org/apache/sshd/client/kex/DHGClient.java
b/sshd-core/src/main/java/org/apache/sshd/client/kex/DHGClient.java
index cf00249..bed61f3 100644
--- a/sshd-core/src/main/java/org/apache/sshd/client/kex/DHGClient.java
+++ b/sshd-core/src/main/java/org/apache/sshd/client/kex/DHGClient.java
@@ -102,8 +102,10 @@ public class DHGClient extends AbstractDHClientKeyExchange
{
public boolean next(int cmd, Buffer buffer) throws Exception {
Session session = getSession();
if (log.isDebugEnabled()) {
- log.debug("next({})[{}] process command={}", this, session,
KeyExchange.getSimpleKexOpcodeName(cmd));
+ log.debug("next({})[{}] process command={}",
+ this, session, KeyExchange.getSimpleKexOpcodeName(cmd));
}
+
if (cmd != SshConstants.SSH_MSG_KEXDH_REPLY) {
throw new
SshException(SshConstants.SSH2_DISCONNECT_KEY_EXCHANGE_FAILED,
"Protocol error: expected packet SSH_MSG_KEXDH_REPLY, got " +
KeyExchange.getSimpleKexOpcodeName(cmd));
@@ -119,7 +121,8 @@ public class DHGClient extends AbstractDHClientKeyExchange {
serverKey = buffer.getRawPublicKey();
String keyAlg = KeyUtils.getKeyType(serverKey);
if (GenericUtils.isEmpty(keyAlg)) {
- throw new SshException("Unsupported server key type: " +
serverKey.getAlgorithm());
+ throw new SshException("Unsupported server key type: " +
serverKey.getAlgorithm()
+ + "[" + serverKey.getFormat() + "]");
}
buffer = new ByteArrayBuffer();
@@ -140,8 +143,10 @@ public class DHGClient extends AbstractDHClientKeyExchange
{
verif.initVerifier(serverKey);
verif.update(h);
if (!verif.verify(sig)) {
- throw new
SshException(SshConstants.SSH2_DISCONNECT_KEY_EXCHANGE_FAILED, "KeyExchange
signature verification failed for key type=" + keyAlg);
+ throw new
SshException(SshConstants.SSH2_DISCONNECT_KEY_EXCHANGE_FAILED,
+ "KeyExchange signature verification failed for key type=" +
keyAlg);
}
+
return true;
}
}
diff --git
a/sshd-core/src/main/java/org/apache/sshd/client/kex/DHGEXClient.java
b/sshd-core/src/main/java/org/apache/sshd/client/kex/DHGEXClient.java
index ced2125..2e23683 100644
--- a/sshd-core/src/main/java/org/apache/sshd/client/kex/DHGEXClient.java
+++ b/sshd-core/src/main/java/org/apache/sshd/client/kex/DHGEXClient.java
@@ -23,6 +23,7 @@ import java.math.BigInteger;
import java.util.Objects;
import org.apache.sshd.common.NamedFactory;
+import org.apache.sshd.common.PropertyResolverUtils;
import org.apache.sshd.common.SshConstants;
import org.apache.sshd.common.SshException;
import org.apache.sshd.common.config.keys.KeyUtils;
@@ -42,6 +43,9 @@ import org.apache.sshd.common.util.security.SecurityUtils;
* @author <a href="mailto:d...@mina.apache.org";>Apache MINA SSHD Project</a>
*/
public class DHGEXClient extends AbstractDHClientKeyExchange {
+ public static final String PROP_DHGEX_CLIENT_MIN_KEY = "dhgex-client-min";
+ public static final String PROP_DHGEX_CLIENT_MAX_KEY = "dhgex-client-max";
+
protected final DHFactory factory;
protected byte expected;
protected int min = SecurityUtils.MIN_DHGEX_KEY_SIZE;
@@ -86,10 +90,19 @@ public class DHGEXClient extends
AbstractDHClientKeyExchange {
@Override
public void init(Session s, byte[] v_s, byte[] v_c, byte[] i_s, byte[]
i_c) throws Exception {
super.init(s, v_s, v_c, i_s, i_c);
+
+ // SSHD-941 give the user a chance to intervene in the choice
+ min = PropertyResolverUtils.getIntProperty(s,
PROP_DHGEX_CLIENT_MIN_KEY, min);
+ max = PropertyResolverUtils.getIntProperty(s,
PROP_DHGEX_CLIENT_MAX_KEY, max);
+ prf = Math.min(SecurityUtils.PREFERRED_DHGEX_KEY_SIZE, max);
if (log.isDebugEnabled()) {
log.debug("init({})[{}] Send SSH_MSG_KEX_DH_GEX_REQUEST - min={},
prf={}, max={}",
this, s, min, prf, max);
}
+ if ((max < min) || (prf < min) || (max < prf)) {
+ throw new
SshException(SshConstants.SSH2_DISCONNECT_KEY_EXCHANGE_FAILED,
+ "Protocol error: bad parameters " + min + " !< " + prf + " !<
" + max);
+ }
Buffer buffer =
s.createBuffer(SshConstants.SSH_MSG_KEX_DH_GEX_REQUEST, Integer.SIZE);
buffer.putInt(min);
diff --git
a/sshd-core/src/main/java/org/apache/sshd/server/kex/DHGEXServer.java
b/sshd-core/src/main/java/org/apache/sshd/server/kex/DHGEXServer.java
index 55d791f..7a4b8f2 100644
--- a/sshd-core/src/main/java/org/apache/sshd/server/kex/DHGEXServer.java
+++ b/sshd-core/src/main/java/org/apache/sshd/server/kex/DHGEXServer.java
@@ -31,6 +31,7 @@ import java.util.Objects;
import org.apache.sshd.common.Factory;
import org.apache.sshd.common.FactoryManager;
import org.apache.sshd.common.NamedFactory;
+import org.apache.sshd.common.PropertyResolverUtils;
import org.apache.sshd.common.SshConstants;
import org.apache.sshd.common.SshException;
import org.apache.sshd.common.kex.DHFactory;
@@ -55,6 +56,9 @@ import org.apache.sshd.server.session.ServerSession;
* @author <a href="mailto:d...@mina.apache.org";>Apache MINA SSHD Project</a>
*/
public class DHGEXServer extends AbstractDHServerKeyExchange {
+ public static final String PROP_DHGEX_SERVER_MIN_KEY = "dhgex-server-min";
+ public static final String PROP_DHGEX_SERVER_MAX_KEY = "dhgex-server-max";
+
protected final DHFactory factory;
protected DHG dh;
protected int min;
@@ -112,9 +116,11 @@ public class DHGEXServer extends
AbstractDHServerKeyExchange {
if ((cmd == SshConstants.SSH_MSG_KEX_DH_GEX_REQUEST_OLD)
&& (expected == SshConstants.SSH_MSG_KEX_DH_GEX_REQUEST)) {
oldRequest = true;
- min = SecurityUtils.MIN_DHGEX_KEY_SIZE;
+ min = PropertyResolverUtils.getIntProperty(
+ session, PROP_DHGEX_SERVER_MIN_KEY,
SecurityUtils.MIN_DHGEX_KEY_SIZE);
prf = buffer.getInt();
- max = SecurityUtils.getMaxDHGroupExchangeKeySize();
+ max = PropertyResolverUtils.getIntProperty(
+ session, PROP_DHGEX_SERVER_MAX_KEY,
SecurityUtils.getMaxDHGroupExchangeKeySize());
if ((max < min) || (prf < min) || (max < prf)) {
throw new
SshException(SshConstants.SSH2_DISCONNECT_KEY_EXCHANGE_FAILED,
@@ -307,7 +313,6 @@ public class DHGEXServer extends
AbstractDHServerKeyExchange {
protected List<Moduli.DhGroup> loadModuliGroups() throws IOException {
Session session = getServerSession();
String moduliStr = session.getString(ServerFactoryManager.MODULI_URL);
-
List<Moduli.DhGroup> groups = null;
if (!GenericUtils.isEmpty(moduliStr)) {
try {
@@ -337,8 +342,8 @@ public class DHGEXServer extends
AbstractDHServerKeyExchange {
}
if (log.isDebugEnabled()) {
- log.debug("loadModuliGroups({})[{}] Loaded moduli groups from {}",
- this, session, moduliStr);
+ log.debug("loadModuliGroups({})[{}] Loaded {} moduli groups from
{}",
+ this, session, GenericUtils.size(groups), moduliStr);
}
return groups;
}
diff --git a/sshd-core/src/main/java/org/apache/sshd/server/kex/DHGServer.java
b/sshd-core/src/main/java/org/apache/sshd/server/kex/DHGServer.java
index 3dfefad..d74353b 100644
--- a/sshd-core/src/main/java/org/apache/sshd/server/kex/DHGServer.java
+++ b/sshd-core/src/main/java/org/apache/sshd/server/kex/DHGServer.java
@@ -88,7 +88,8 @@ public class DHGServer extends AbstractDHServerKeyExchange {
public boolean next(int cmd, Buffer buffer) throws Exception {
ServerSession session = getServerSession();
if (log.isDebugEnabled()) {
- log.debug("next({})[{}] process command={}", this, session,
KeyExchange.getSimpleKexOpcodeName(cmd));
+ log.debug("next({})[{}] process command={}",
+ this, session, KeyExchange.getSimpleKexOpcodeName(cmd));
}
if (cmd != SshConstants.SSH_MSG_KEXDH_INIT) {
