Support multiple authentication methods (#825)

* Offer password SSH authentication after publickey

* git: re-add back button handling

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

* Hide unsupported authentication methods

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

* GitCommandExecutor: cleanup and address build warning

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

* Address review comments

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

* DecryptActivity: hide menu items until decrypt finishes

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

* Add changelog entry

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

Co-authored-by: Harsh Shandilya <me@msfjarvis.dev>

4 files changed, 32 insertions, 28 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 04ac0340..01ad9680 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ All notable changes to this project will be documented in this file.
 -   Add [Bromite](https://www.bromite.org/) and [Ungoogled Chromium](https://git.droidware.info/wchen342/ungoogled-chromium-android) to supported browsers list for Autofill
 -   Add ability to view the Git commit log
 -   Allow generating ECDSA and ED25519 keys for SSH
+-   Add support for multiple/fallback authentication methods for SSH
 
 ### Changed
 
diff --git a/app/src/main/java/com/zeapo/pwdstore/git/operation/GitOperation.kt b/app/src/main/java/com/zeapo/pwdstore/git/operation/GitOperation.kt
index ad6a3e29..85c38c6a 100644
--- a/app/src/main/java/com/zeapo/pwdstore/git/operation/GitOperation.kt
+++ b/app/src/main/java/com/zeapo/pwdstore/git/operation/GitOperation.kt
@@ -19,7 +19,7 @@ import com.zeapo.pwdstore.UserPreference
 import com.zeapo.pwdstore.git.GitCommandExecutor
 import com.zeapo.pwdstore.git.config.AuthMode
 import com.zeapo.pwdstore.git.config.GitSettings
-import com.zeapo.pwdstore.git.sshj.SshAuthData
+import com.zeapo.pwdstore.git.sshj.SshAuthMethod
 import com.zeapo.pwdstore.git.sshj.SshKey
 import com.zeapo.pwdstore.git.sshj.SshjSessionFactory
 import com.zeapo.pwdstore.utils.BiometricAuthenticator
@@ -99,8 +99,8 @@ abstract class GitOperation(protected val callingActivity: FragmentActivity) {
         }
     }
 
-    private fun registerAuthProviders(authData: SshAuthData, credentialsProvider: CredentialsProvider? = null) {
-        sshSessionFactory = SshjSessionFactory(authData, hostKeyFile)
+    private fun registerAuthProviders(authMethod: SshAuthMethod, credentialsProvider: CredentialsProvider? = null) {
+        sshSessionFactory = SshjSessionFactory(authMethod, hostKeyFile)
         commands.filterIsInstance<TransportCommand<*, *>>().forEach { command ->
             command.setTransportConfigCallback { transport: Transport ->
                 (transport as? SshTransport)?.sshSessionFactory = sshSessionFactory
@@ -154,8 +154,7 @@ abstract class GitOperation(protected val callingActivity: FragmentActivity) {
                     }
                     when (result) {
                         is BiometricAuthenticator.Result.Success -> {
-                            registerAuthProviders(
-                                SshAuthData.SshKey(CredentialFinder(callingActivity, AuthMode.SshKey)))
+                            registerAuthProviders(SshAuthMethod.SshKey(callingActivity))
                         }
                         is BiometricAuthenticator.Result.Cancelled -> {
                             return Err(SSHException(DisconnectReason.AUTH_CANCELLED_BY_USER))
@@ -173,7 +172,7 @@ abstract class GitOperation(protected val callingActivity: FragmentActivity) {
                         }
                     }
                 } else {
-                    registerAuthProviders(SshAuthData.SshKey(CredentialFinder(callingActivity, AuthMode.SshKey)))
+                    registerAuthProviders(SshAuthMethod.SshKey(callingActivity))
                 }
             } else {
                 onMissingSshKeyFile()
@@ -181,13 +180,10 @@ abstract class GitOperation(protected val callingActivity: FragmentActivity) {
                 // error, allowing users to make the SSH key selection.
                 return Err(SSHException(DisconnectReason.AUTH_CANCELLED_BY_USER))
             }
-            AuthMode.OpenKeychain -> registerAuthProviders(SshAuthData.OpenKeychain(callingActivity))
+            AuthMode.OpenKeychain -> registerAuthProviders(SshAuthMethod.OpenKeychain(callingActivity))
             AuthMode.Password -> {
-                val credentialFinder = CredentialFinder(callingActivity, AuthMode.Password)
-                val httpsCredentialProvider = HttpsCredentialsProvider(credentialFinder)
-                registerAuthProviders(
-                    SshAuthData.Password(CredentialFinder(callingActivity, AuthMode.Password)),
-                    httpsCredentialProvider)
+                val httpsCredentialProvider = HttpsCredentialsProvider(CredentialFinder(callingActivity, AuthMode.Password))
+                registerAuthProviders(SshAuthMethod.Password(callingActivity), httpsCredentialProvider)
             }
             AuthMode.None -> {
             }
diff --git a/app/src/main/java/com/zeapo/pwdstore/git/sshj/OpenKeychainKeyProvider.kt b/app/src/main/java/com/zeapo/pwdstore/git/sshj/OpenKeychainKeyProvider.kt
index 5cb1b006..cdaa0342 100644
--- a/app/src/main/java/com/zeapo/pwdstore/git/sshj/OpenKeychainKeyProvider.kt
+++ b/app/src/main/java/com/zeapo/pwdstore/git/sshj/OpenKeychainKeyProvider.kt
@@ -39,7 +39,7 @@ import org.openintents.ssh.authentication.response.Response
 import org.openintents.ssh.authentication.response.SigningResponse
 import org.openintents.ssh.authentication.response.SshPublicKeyResponse
 
-class OpenKeychainKeyProvider private constructor(private val activity: FragmentActivity) : KeyProvider, Closeable {
+class OpenKeychainKeyProvider private constructor(activity: FragmentActivity) : KeyProvider, Closeable {
 
     companion object {
 
diff --git a/app/src/main/java/com/zeapo/pwdstore/git/sshj/SshjSessionFactory.kt b/app/src/main/java/com/zeapo/pwdstore/git/sshj/SshjSessionFactory.kt
index a507d50b..f064df33 100644
--- a/app/src/main/java/com/zeapo/pwdstore/git/sshj/SshjSessionFactory.kt
+++ b/app/src/main/java/com/zeapo/pwdstore/git/sshj/SshjSessionFactory.kt
@@ -10,6 +10,8 @@ import com.github.ajalt.timberkt.d
 import com.github.ajalt.timberkt.w
 import com.github.michaelbull.result.getOrElse
 import com.github.michaelbull.result.runCatching
+import com.zeapo.pwdstore.git.config.AuthMode
+import com.zeapo.pwdstore.git.operation.CredentialFinder
 import java.io.File
 import java.io.IOException
 import java.io.InputStream
@@ -28,6 +30,8 @@ import net.schmizz.sshj.common.SecurityUtils
 import net.schmizz.sshj.connection.channel.direct.Session
 import net.schmizz.sshj.transport.verification.FingerprintVerifier
 import net.schmizz.sshj.transport.verification.HostKeyVerifier
+import net.schmizz.sshj.userauth.method.AuthPassword
+import net.schmizz.sshj.userauth.method.AuthPublickey
 import net.schmizz.sshj.userauth.password.PasswordFinder
 import net.schmizz.sshj.userauth.password.Resource
 import org.eclipse.jgit.transport.CredentialsProvider
@@ -36,10 +40,10 @@ import org.eclipse.jgit.transport.SshSessionFactory
 import org.eclipse.jgit.transport.URIish
 import org.eclipse.jgit.util.FS
 
-sealed class SshAuthData {
-    class Password(val passwordFinder: InteractivePasswordFinder) : SshAuthData()
-    class SshKey(val passphraseFinder: InteractivePasswordFinder) : SshAuthData()
-    class OpenKeychain(val activity: FragmentActivity) : SshAuthData()
+sealed class SshAuthMethod(val activity: FragmentActivity) {
+    class Password(activity: FragmentActivity) : SshAuthMethod(activity)
+    class SshKey(activity: FragmentActivity) : SshAuthMethod(activity)
+    class OpenKeychain(activity: FragmentActivity) : SshAuthMethod(activity)
 }
 
 abstract class InteractivePasswordFinder : PasswordFinder {
@@ -62,12 +66,12 @@ abstract class InteractivePasswordFinder : PasswordFinder {
     final override fun shouldRetry(resource: Resource<*>?) = true
 }
 
-class SshjSessionFactory(private val authData: SshAuthData, private val hostKeyFile: File) : SshSessionFactory() {
+class SshjSessionFactory(private val authMethod: SshAuthMethod, private val hostKeyFile: File) : SshSessionFactory() {
 
     private var currentSession: SshjSession? = null
 
     override fun getSession(uri: URIish, credentialsProvider: CredentialsProvider?, fs: FS?, tms: Int): RemoteSession {
-        return currentSession ?: SshjSession(uri, uri.user, authData, hostKeyFile).connect().also {
+        return currentSession ?: SshjSession(uri, uri.user, authMethod, hostKeyFile).connect().also {
             d { "New SSH connection created" }
             currentSession = it
         }
@@ -100,7 +104,7 @@ private fun makeTofuHostKeyVerifier(hostKeyFile: File): HostKeyVerifier {
     }
 }
 
-private class SshjSession(uri: URIish, private val username: String, private val authData: SshAuthData, private val hostKeyFile: File) : RemoteSession {
+private class SshjSession(uri: URIish, private val username: String, private val authMethod: SshAuthMethod, private val hostKeyFile: File) : RemoteSession {
 
     private lateinit var ssh: SSHClient
     private var currentCommand: Session? = null
@@ -124,17 +128,20 @@ private class SshjSession(uri: URIish, private val username: String, private val
         ssh.connect(uri.host, uri.port.takeUnless { it == -1 } ?: 22)
         if (!ssh.isConnected)
             throw IOException()
-        when (authData) {
-            is SshAuthData.Password -> {
-                ssh.authPassword(username, authData.passwordFinder)
+        val passwordAuth = AuthPassword(CredentialFinder(authMethod.activity, AuthMode.Password))
+        when (authMethod) {
+            is SshAuthMethod.Password -> {
+                ssh.auth(username, passwordAuth)
             }
-            is SshAuthData.SshKey -> {
-                ssh.authPublickey(username, SshKey.provide(ssh, authData.passphraseFinder))
+            is SshAuthMethod.SshKey -> {
+                val pubkeyAuth = AuthPublickey(SshKey.provide(ssh, CredentialFinder(authMethod.activity, AuthMode.SshKey)))
+                ssh.auth(username, pubkeyAuth, passwordAuth)
             }
-            is SshAuthData.OpenKeychain -> {
+            is SshAuthMethod.OpenKeychain -> {
                 runBlocking {
-                    OpenKeychainKeyProvider.prepareAndUse(authData.activity) { provider ->
-                        ssh.authPublickey(username, provider)
+                    OpenKeychainKeyProvider.prepareAndUse(authMethod.activity) { provider ->
+                        val openKeychainAuth = AuthPublickey(provider)
+                        ssh.auth(username, openKeychainAuth, passwordAuth)
                     }
                 }
             }