SECURITY-3319

src/main/java/org/jenkinsci/plugins/gitserver/ssh/AbstractGitCommand.java

@@ -7,6 +7,7 @@
 import org.kohsuke.args4j.Argument;
 import org.kohsuke.args4j.CmdLineException;
 import org.kohsuke.args4j.CmdLineParser;
+import org.kohsuke.args4j.ParserProperties;
 
 /**
  * Implements the SSH {@link Command} for the server side git command.
@@ -24,7 +25,8 @@ abstract class AbstractGitCommand extends AsynchronousCommand {
     @Override
     protected final int runCommand() throws Exception {
             try {
-                new CmdLineParser(this).parseArgument(getCmdLine().subList(1,getCmdLine().size()));
+                ParserProperties properties = ParserProperties.defaults().withAtSyntax(false);
+                new CmdLineParser(this, properties).parseArgument(getCmdLine().subList(1,getCmdLine().size()));
             } catch (CmdLineException e) {
                 throw new AbortException(e.getMessage());
             }

src/test/java/org/jenkinsci/plugins/gitserver/ssh/ReceivePackCommandTest.java

@@ -0,0 +1,97 @@
+package org.jenkinsci.plugins.gitserver.ssh;
+
+import hudson.Functions;
+import java.io.ByteArrayOutputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.EnumSet;
+import org.apache.sshd.client.SshClient;
+import org.apache.sshd.client.channel.ClientChannel;
+import org.apache.sshd.client.channel.ClientChannelEvent;
+import org.apache.sshd.client.future.ConnectFuture;
+import org.apache.sshd.client.keyverifier.AcceptAllServerKeyVerifier;
+import org.apache.sshd.client.session.ClientSession;
+import org.jenkinsci.main.modules.cli.auth.ssh.PublicKeySignatureWriter;
+import org.jenkinsci.main.modules.cli.auth.ssh.UserPropertyImpl;
+import org.jenkinsci.main.modules.sshd.SSHD;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.jvnet.hudson.test.Issue;
+import org.jvnet.hudson.test.JenkinsRule;
+
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.security.KeyPair;
+import java.security.KeyPairGenerator;
+import java.security.NoSuchAlgorithmException;
+import java.util.concurrent.TimeUnit;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.not;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assume.assumeFalse;
+
+/**
+ * This class contains code borrowed and adapted from the Jenkins SSHD plugin.
+ * Original source: org.jenkinsci.main.modules.sshd.SSHDTest.java
+ */
+public class ReceivePackCommandTest {
+
+    @Rule
+    public JenkinsRule j = new JenkinsRule();
+
+    @Before
+    public void setUp() {
+        assumeFalse(Functions.isWindows());
+    }
+
+    @Test
+    @Issue("SECURITY-3319")
+    public void shouldNotParseAtChar() throws Exception {
+        hudson.model.User enabled = hudson.model.User.getOrCreateByIdOrFullName("enabled");
+        KeyPair keyPair = generateKeys(enabled);
+        SSHD server = SSHD.get();
+        server.setPort(0);
+        server.start();
+
+        Path tempPath = Files.createTempFile("tempFile", ".txt");
+        tempPath.toFile().deleteOnExit();
+        String content = "AtGotParsed";
+        Files.write(tempPath, content.getBytes());
+
+        try (SshClient client = SshClient.setUpDefaultClient()) {
+            client.setServerKeyVerifier(AcceptAllServerKeyVerifier.INSTANCE);
+            client.start();
+            ConnectFuture future = client.connect("enabled", new InetSocketAddress(server.getActualPort()));
+            try (ClientSession session = future.verify(10, TimeUnit.SECONDS).getSession()) {
+                session.addPublicKeyIdentity(keyPair);
+                assertTrue(session.auth().await(10, TimeUnit.SECONDS));
+
+                String command = "git-receive-pack @" + tempPath;
+                try (ClientChannel channel = session.createExecChannel(command)) {
+                    ByteArrayOutputStream errorStream = new ByteArrayOutputStream();
+                    channel.setErr(errorStream);
+                    channel.open().verify(5, TimeUnit.SECONDS);
+                    channel.waitFor(EnumSet.of(ClientChannelEvent.CLOSED), TimeUnit.SECONDS.toMillis(5));
+
+                    String errorMessage = errorStream.toString();
+                    assertThat(errorMessage, containsString("@" + tempPath));
+                    assertThat(errorMessage, not(containsString(content)));
+                }
+            }
+        }
+    }
+
+    private static KeyPair generateKeys(hudson.model.User user) throws NoSuchAlgorithmException, IOException {
+        // I'd prefer to generate Ed25519 keys here, but the API is too awkward currently
+        // ECDSA keys would be even more awkward as we'd need a copy of the curve parameters
+        KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA");
+        generator.initialize(2048);
+        KeyPair keyPair = generator.generateKeyPair();
+        String encodedPublicKey = "ssh-rsa " + new PublicKeySignatureWriter().asString(keyPair.getPublic());
+        user.addProperty(new UserPropertyImpl(encodedPublicKey));
+        return keyPair;
+    }
+}