fix: SEC-3/CONC-1/2/3 vault zeroize + async mutex + cancellation tokens

- Vault key uses Zeroizing<[u8; 32]>, passwords zeroized after use
- vault/credentials Mutex upgraded to tokio::sync::Mutex
- CWD tracker + monitor use CancellationToken for clean shutdown
- Monitor exec_command has 10s timeout, 3-strike dead connection heuristic

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src-tauri/Cargo.lock

@@ -8913,9 +8913,11 @@ dependencies = [
  "thiserror 2.0.18",
  "tokio",
  "tokio-rustls",
+ "tokio-util",
  "ureq",
  "uuid",
  "x509-cert",
+ "zeroize",
 ]
 
 [[package]]

src-tauri/Cargo.toml

@@ -33,6 +33,8 @@ uuid = { version = "1", features = ["v4"] }
 base64 = "0.22"
 dashmap = "6"
 tokio = { version = "1", features = ["full"] }
+tokio-util = "0.7"
+zeroize = { version = "1", features = ["derive"] }
 async-trait = "0.1"
 log = "0.4"
 env_logger = "0.11"

src-tauri/src/commands/credentials.rs

@@ -3,34 +3,16 @@ use tauri::State;
 use crate::credentials::Credential;
 use crate::AppState;
 
-/// Guard helper: lock the credentials mutex and return a ref to the inner
-/// `CredentialService`, or a "Vault is locked" error if the vault has not
-/// been unlocked for this session.
-///
-/// This is a macro rather than a function because returning a `MutexGuard`
-/// from a helper function would require lifetime annotations that complicate
-/// the tauri command signatures unnecessarily.
-macro_rules! require_unlocked {
-    ($state:expr) => {{
-        let guard = $state
-            .credentials
-            .lock()
-            .map_err(|_| "Credentials mutex was poisoned".to_string())?;
-        if guard.is_none() {
-            return Err("Vault is locked — call unlock before accessing credentials".into());
-        }
-        // SAFETY: we just checked `is_none` above, so `unwrap` cannot panic.
-        guard
-    }};
-}
-
 /// Return all credentials ordered by name.
 ///
 /// Secret values (passwords, private keys) are never included — only metadata.
 #[tauri::command]
-pub fn list_credentials(state: State<'_, AppState>) -> Result<Vec<Credential>, String> {
+pub async fn list_credentials(state: State<'_, AppState>) -> Result<Vec<Credential>, String> {
-    let guard = require_unlocked!(state);
+    let guard = state.credentials.lock().await;
-    guard.as_ref().unwrap().list()
+    let svc = guard
+        .as_ref()
+        .ok_or_else(|| "Vault is locked — call unlock before accessing credentials".to_string())?;
+    svc.list()
 }
 
 /// Store a new username/password credential.
@@ -39,18 +21,18 @@ pub fn list_credentials(state: State<'_, AppState>) -> Result<Vec<Credential>, S
 /// Returns the created credential record (without the plaintext password).
 /// `domain` is `None` for non-domain credentials; `Some("")` is treated as NULL.
 #[tauri::command]
-pub fn create_password(
+pub async fn create_password(
     name: String,
     username: String,
     password: String,
     domain: Option<String>,
     state: State<'_, AppState>,
 ) -> Result<Credential, String> {
-    let guard = require_unlocked!(state);
+    let guard = state.credentials.lock().await;
-    guard
+    let svc = guard
         .as_ref()
-        .unwrap()
+        .ok_or_else(|| "Vault is locked — call unlock before accessing credentials".to_string())?;
-        .create_password(name, username, password, domain)
+    svc.create_password(name, username, password, domain)
 }
 
 /// Store a new SSH private key credential.
@@ -59,18 +41,18 @@ pub fn create_password(
 /// Pass `None` for `passphrase` when the key has no passphrase.
 /// Returns the created credential record without any secret material.
 #[tauri::command]
-pub fn create_ssh_key(
+pub async fn create_ssh_key(
     name: String,
     username: String,
     private_key_pem: String,
     passphrase: Option<String>,
     state: State<'_, AppState>,
 ) -> Result<Credential, String> {
-    let guard = require_unlocked!(state);
+    let guard = state.credentials.lock().await;
-    guard
+    let svc = guard
         .as_ref()
-        .unwrap()
+        .ok_or_else(|| "Vault is locked — call unlock before accessing credentials".to_string())?;
-        .create_ssh_key(name, username, private_key_pem, passphrase)
+    svc.create_ssh_key(name, username, private_key_pem, passphrase)
 }
 
 /// Delete a credential by id.
@@ -78,21 +60,30 @@ pub fn create_ssh_key(
 /// For SSH key credentials, the associated `ssh_keys` row is also deleted.
 /// Returns `Err` if the vault is locked or the id does not exist.
 #[tauri::command]
-pub fn delete_credential(id: i64, state: State<'_, AppState>) -> Result<(), String> {
+pub async fn delete_credential(id: i64, state: State<'_, AppState>) -> Result<(), String> {
-    let guard = require_unlocked!(state);
+    let guard = state.credentials.lock().await;
-    guard.as_ref().unwrap().delete(id)
+    let svc = guard
+        .as_ref()
+        .ok_or_else(|| "Vault is locked — call unlock before accessing credentials".to_string())?;
+    svc.delete(id)
 }
 
 /// Decrypt and return the password for a credential.
 #[tauri::command]
-pub fn decrypt_password(credential_id: i64, state: State<'_, AppState>) -> Result<String, String> {
+pub async fn decrypt_password(credential_id: i64, state: State<'_, AppState>) -> Result<String, String> {
-    let guard = require_unlocked!(state);
+    let guard = state.credentials.lock().await;
-    guard.as_ref().unwrap().decrypt_password(credential_id)
+    let svc = guard
+        .as_ref()
+        .ok_or_else(|| "Vault is locked — call unlock before accessing credentials".to_string())?;
+    svc.decrypt_password(credential_id)
 }
 
 /// Decrypt and return the SSH private key and passphrase.
 #[tauri::command]
-pub fn decrypt_ssh_key(ssh_key_id: i64, state: State<'_, AppState>) -> Result<(String, String), String> {
+pub async fn decrypt_ssh_key(ssh_key_id: i64, state: State<'_, AppState>) -> Result<(String, String), String> {
-    let guard = require_unlocked!(state);
+    let guard = state.credentials.lock().await;
-    guard.as_ref().unwrap().decrypt_ssh_key(ssh_key_id)
+    let svc = guard
+        .as_ref()
+        .ok_or_else(|| "Vault is locked — call unlock before accessing credentials".to_string())?;
+    svc.decrypt_ssh_key(ssh_key_id)
 }

src-tauri/src/commands/vault.rs

@@ -1,4 +1,5 @@
 use tauri::State;
+use zeroize::Zeroize;
 
 use crate::vault::{self, VaultService};
 use crate::credentials::CredentialService;
@@ -21,14 +22,15 @@ pub fn is_first_run(state: State<'_, AppState>) -> bool {
 /// Returns `Err` if the vault has already been set up or if any storage
 /// operation fails.
 #[tauri::command]
-pub fn create_vault(password: String, state: State<'_, AppState>) -> Result<(), String> {
+pub async fn create_vault(mut password: String, state: State<'_, AppState>) -> Result<(), String> {
+    let result = async {
         if !state.is_first_run() {
             return Err("Vault already exists — use unlock instead of create".into());
         }
 
         let salt = vault::generate_salt();
         let key = vault::derive_key(&password, &salt);
-    let vs = VaultService::new(key);
+        let vs = VaultService::new(key.clone());
 
         // Persist the salt so we can re-derive the key on future unlocks.
         state.settings.set("vault_salt", &hex::encode(salt))?;
@@ -39,10 +41,14 @@ pub fn create_vault(password: String, state: State<'_, AppState>) -> Result<(),
 
         // Activate the vault and credentials service for this session.
         let cred_svc = CredentialService::new(state.db.clone(), VaultService::new(key));
-    *state.credentials.lock().unwrap() = Some(cred_svc);
+        *state.credentials.lock().await = Some(cred_svc);
-    *state.vault.lock().unwrap() = Some(vs);
+        *state.vault.lock().await = Some(vs);
 
         Ok(())
+    }.await;
+
+    password.zeroize();
+    result
 }
 
 /// Unlock an existing vault using the master password.
@@ -52,7 +58,8 @@ pub fn create_vault(password: String, state: State<'_, AppState>) -> Result<(),
 ///
 /// Returns `Err("Incorrect master password")` if the password is wrong.
 #[tauri::command]
-pub fn unlock(password: String, state: State<'_, AppState>) -> Result<(), String> {
+pub async fn unlock(mut password: String, state: State<'_, AppState>) -> Result<(), String> {
+    let result = async {
         let salt_hex = state
             .settings
             .get("vault_salt")
@@ -62,7 +69,7 @@ pub fn unlock(password: String, state: State<'_, AppState>) -> Result<(), String
             .map_err(|e| format!("Stored vault salt is corrupt: {e}"))?;
 
         let key = vault::derive_key(&password, &salt);
-    let vs = VaultService::new(key);
+        let vs = VaultService::new(key.clone());
 
         // Verify the password by decrypting the check value.
         let check_blob = state
@@ -80,14 +87,18 @@ pub fn unlock(password: String, state: State<'_, AppState>) -> Result<(), String
 
         // Activate the vault and credentials service for this session.
         let cred_svc = CredentialService::new(state.db.clone(), VaultService::new(key));
-    *state.credentials.lock().unwrap() = Some(cred_svc);
+        *state.credentials.lock().await = Some(cred_svc);
-    *state.vault.lock().unwrap() = Some(vs);
+        *state.vault.lock().await = Some(vs);
 
         Ok(())
+    }.await;
+
+    password.zeroize();
+    result
 }
 
 /// Returns `true` if the vault is currently unlocked for this session.
 #[tauri::command]
-pub fn is_unlocked(state: State<'_, AppState>) -> bool {
+pub async fn is_unlocked(state: State<'_, AppState>) -> Result<bool, String> {
-    state.is_unlocked()
+    Ok(state.is_unlocked().await)
 }

src-tauri/src/lib.rs

@@ -23,7 +23,6 @@ pub mod scanner;
 pub mod commands;
 
 use std::path::PathBuf;
-use std::sync::Mutex;
 
 use db::Database;
 use vault::VaultService;
@@ -41,10 +40,10 @@ use mcp::error_watcher::ErrorWatcher;
 
 pub struct AppState {
     pub db: Database,
-    pub vault: Mutex<Option<VaultService>>,
+    pub vault: tokio::sync::Mutex<Option<VaultService>>,
     pub settings: SettingsService,
     pub connections: ConnectionService,
-    pub credentials: Mutex<Option<CredentialService>>,
+    pub credentials: tokio::sync::Mutex<Option<CredentialService>>,
     pub ssh: SshService,
     pub sftp: SftpService,
     pub rdp: RdpService,
@@ -62,10 +61,10 @@ impl AppState {
         database.migrate()?;
         Ok(Self {
             db: database.clone(),
-            vault: Mutex::new(None),
+            vault: tokio::sync::Mutex::new(None),
             settings: SettingsService::new(database.clone()),
             connections: ConnectionService::new(database.clone()),
-            credentials: Mutex::new(None),
+            credentials: tokio::sync::Mutex::new(None),
             ssh: SshService::new(database.clone()),
             sftp: SftpService::new(),
             rdp: RdpService::new(),
@@ -85,8 +84,8 @@ impl AppState {
         self.settings.get("vault_salt").unwrap_or_default().is_empty()
     }
 
-    pub fn is_unlocked(&self) -> bool {
+    pub async fn is_unlocked(&self) -> bool {
-        self.vault.lock().unwrap().is_some()
+        self.vault.lock().await.is_some()
     }
 }
 

src-tauri/src/ssh/cwd.rs

@@ -16,6 +16,7 @@ use russh::ChannelMsg;
 use tauri::{AppHandle, Emitter};
 use tokio::sync::watch;
 use tokio::sync::Mutex as TokioMutex;
+use tokio_util::sync::CancellationToken;
 
 use crate::ssh::session::SshClient;
 
@@ -39,13 +40,15 @@ impl CwdTracker {
     /// Spawn a background tokio task that polls `pwd` every 2 seconds on a
     /// separate exec channel.
     ///
-    /// The task runs until the SSH connection is closed or the channel cannot
+    /// The task runs until cancelled via the `CancellationToken`, or until the
-    /// be opened. CWD changes are emitted as `ssh:cwd:{session_id}` events.
+    /// SSH connection is closed or the channel cannot be opened.
+    /// CWD changes are emitted as `ssh:cwd:{session_id}` events.
     pub fn start(
         &self,
         handle: Arc<TokioMutex<Handle<SshClient>>>,
         app_handle: AppHandle,
         session_id: String,
+        cancel: CancellationToken,
     ) {
         let sender = self._sender.clone();
 
@@ -56,6 +59,10 @@ impl CwdTracker {
             let mut previous_cwd = String::new();
 
             loop {
+                if cancel.is_cancelled() {
+                    break;
+                }
+
                 // Open a fresh exec channel for each `pwd` invocation.
                 // Some SSH servers do not allow multiple exec requests on a
                 // single channel, so we open a new one each time.
@@ -119,8 +126,11 @@ impl CwdTracker {
                     }
                 }
 
-                // Wait 2 seconds before the next poll.
+                // Wait 2 seconds before the next poll, or cancel.
-                tokio::time::sleep(tokio::time::Duration::from_secs(2)).await;
+                tokio::select! {
+                    _ = tokio::time::sleep(tokio::time::Duration::from_secs(2)) => {}
+                    _ = cancel.cancelled() => { break; }
+                }
             }
 
             debug!("CWD tracker for session {} stopped", session_id);

src-tauri/src/ssh/monitor.rs

@@ -6,11 +6,13 @@
 
 use std::sync::Arc;
 
+use log::warn;
 use russh::client::Handle;
 use russh::ChannelMsg;
 use serde::Serialize;
 use tauri::{AppHandle, Emitter};
 use tokio::sync::Mutex as TokioMutex;
+use tokio_util::sync::CancellationToken;
 
 use crate::ssh::session::SshClient;
 
@@ -30,26 +32,53 @@ pub struct SystemStats {
 }
 
 /// Spawn a background task that polls system stats every 5 seconds.
+///
+/// The task runs until cancelled via the `CancellationToken`, or until the
+/// SSH connection is closed.
 pub fn start_monitor(
     handle: Arc<TokioMutex<Handle<SshClient>>>,
     app_handle: AppHandle,
     session_id: String,
+    cancel: CancellationToken,
 ) {
     tokio::spawn(async move {
         // Brief delay to let the shell start up
         tokio::time::sleep(tokio::time::Duration::from_secs(2)).await;
 
+        let mut consecutive_timeouts: u32 = 0;
+
         loop {
+            if cancel.is_cancelled() {
+                break;
+            }
+
             let stats = collect_stats(&handle).await;
 
-            if let Some(stats) = stats {
+            match stats {
+                Some(stats) => {
+                    consecutive_timeouts = 0;
                     let _ = app_handle.emit(
                         &format!("ssh:monitor:{}", session_id),
                         &stats,
                     );
                 }
+                None => {
+                    consecutive_timeouts += 1;
+                    if consecutive_timeouts >= 3 {
+                        warn!(
+                            "SSH monitor for session {}: 3 consecutive failures, stopping",
+                            session_id
+                        );
+                        break;
+                    }
+                }
+            }
 
-            tokio::time::sleep(tokio::time::Duration::from_secs(5)).await;
+            // Wait 5 seconds before the next poll, or cancel.
+            tokio::select! {
+                _ = tokio::time::sleep(tokio::time::Duration::from_secs(5)) => {}
+                _ = cancel.cancelled() => { break; }
+            }
         }
     });
 }
@@ -125,7 +154,24 @@ fn parse_stats(raw: &str) -> Option<SystemStats> {
     })
 }
 
+/// Execute a command on a separate exec channel with a 10-second timeout.
 async fn exec_command(handle: &Arc<TokioMutex<Handle<SshClient>>>, cmd: &str) -> Option<String> {
+    let result = tokio::time::timeout(
+        std::time::Duration::from_secs(10),
+        exec_command_inner(handle, cmd),
+    )
+    .await;
+
+    match result {
+        Ok(output) => output,
+        Err(_) => {
+            warn!("SSH monitor exec_command timed out after 10s");
+            None
+        }
+    }
+}
+
+async fn exec_command_inner(handle: &Arc<TokioMutex<Handle<SshClient>>>, cmd: &str) -> Option<String> {
     let mut channel = {
         let h = handle.lock().await;
         h.channel_open_session().await.ok()?

src-tauri/src/ssh/session.rs

@@ -17,6 +17,7 @@ use crate::mcp::error_watcher::ErrorWatcher;
 use crate::sftp::SftpService;
 use crate::ssh::cwd::CwdTracker;
 use crate::ssh::host_key::{HostKeyResult, HostKeyStore};
+use tokio_util::sync::CancellationToken;
 
 pub enum AuthMethod {
     Password(String),
@@ -47,6 +48,7 @@ pub struct SshSession {
     pub handle: Arc<TokioMutex<Handle<SshClient>>>,
     pub command_tx: mpsc::UnboundedSender<ChannelCommand>,
     pub cwd_tracker: Option<CwdTracker>,
+    pub cancel_token: CancellationToken,
 }
 
 pub struct SshClient {
@@ -135,10 +137,11 @@ impl SshService {
         let channel_id = channel.id();
         let handle = Arc::new(TokioMutex::new(handle));
         let (command_tx, mut command_rx) = mpsc::unbounded_channel::<ChannelCommand>();
+        let cancel_token = CancellationToken::new();
         let cwd_tracker = CwdTracker::new();
-        cwd_tracker.start(handle.clone(), app_handle.clone(), session_id.clone());
+        cwd_tracker.start(handle.clone(), app_handle.clone(), session_id.clone(), cancel_token.clone());
 
-        let session = Arc::new(SshSession { id: session_id.clone(), hostname: hostname.to_string(), port, username: username.to_string(), channel_id, handle: handle.clone(), command_tx: command_tx.clone(), cwd_tracker: Some(cwd_tracker) });
+        let session = Arc::new(SshSession { id: session_id.clone(), hostname: hostname.to_string(), port, username: username.to_string(), channel_id, handle: handle.clone(), command_tx: command_tx.clone(), cwd_tracker: Some(cwd_tracker), cancel_token: cancel_token.clone() });
         self.sessions.insert(session_id.clone(), session);
 
         {   let h = handle.lock().await;
@@ -158,7 +161,7 @@ impl SshService {
         error_watcher.watch(&session_id);
 
         // Start remote monitoring if enabled (runs on a separate exec channel)
-        crate::ssh::monitor::start_monitor(handle.clone(), app_handle.clone(), session_id.clone());
+        crate::ssh::monitor::start_monitor(handle.clone(), app_handle.clone(), session_id.clone(), cancel_token.clone());
 
         // Inject OSC 7 CWD reporting hook into the user's shell.
         // This enables SFTP CWD following on all platforms (Linux, macOS, FreeBSD).
@@ -246,6 +249,8 @@ impl SshService {
 
     pub async fn disconnect(&self, session_id: &str, sftp_service: &SftpService) -> Result<(), String> {
         let (_, session) = self.sessions.remove(session_id).ok_or_else(|| format!("Session {} not found", session_id))?;
+        // Cancel background tasks (CWD tracker, monitor) before tearing down the connection.
+        session.cancel_token.cancel();
         let _ = session.command_tx.send(ChannelCommand::Shutdown);
         {   let handle = session.handle.lock().await; let _ = handle.disconnect(Disconnect::ByApplication, "", "en").await; }
         sftp_service.remove_client(session_id);

src-tauri/src/vault/mod.rs

@@ -4,6 +4,7 @@ use aes_gcm::{
     Aes256Gcm, Key, Nonce,
 };
 use argon2::{Algorithm, Argon2, Params, Version};
+use zeroize::Zeroizing;
 
 // ---------------------------------------------------------------------------
 // VaultService
@@ -21,18 +22,18 @@ use argon2::{Algorithm, Argon2, Params, Version};
 /// The version prefix allows a future migration to a different algorithm
 /// without breaking existing stored blobs.
 pub struct VaultService {
-    key: [u8; 32],
+    key: Zeroizing<[u8; 32]>,
 }
 
 impl VaultService {
-    pub fn new(key: [u8; 32]) -> Self {
+    pub fn new(key: Zeroizing<[u8; 32]>) -> Self {
         Self { key }
     }
 
     /// Encrypt `plaintext` and return a `v1:{iv_hex}:{sealed_hex}` blob.
     pub fn encrypt(&self, plaintext: &str) -> Result<String, String> {
         // Build the AES-256-GCM cipher from our key.
-        let key = Key::<Aes256Gcm>::from_slice(&self.key);
+        let key = Key::<Aes256Gcm>::from_slice(&*self.key);
         let cipher = Aes256Gcm::new(key);
 
         // Generate a random 12-byte nonce (96-bit is the GCM standard).
@@ -71,7 +72,7 @@ impl VaultService {
             ));
         }
 
-        let key = Key::<Aes256Gcm>::from_slice(&self.key);
+        let key = Key::<Aes256Gcm>::from_slice(&*self.key);
         let cipher = Aes256Gcm::new(key);
         let nonce = Nonce::from_slice(&iv_bytes);
 
@@ -95,7 +96,7 @@ impl VaultService {
 ///   t = 3 iterations
 ///   m = 65536 KiB (64 MiB) memory
 ///   p = 4 parallelism lanes
-pub fn derive_key(password: &str, salt: &[u8]) -> [u8; 32] {
+pub fn derive_key(password: &str, salt: &[u8]) -> Zeroizing<[u8; 32]> {
     let params = Params::new(
         65536, // m_cost: 64 MiB
         3,     // t_cost: iterations
@@ -106,9 +107,9 @@ pub fn derive_key(password: &str, salt: &[u8]) -> [u8; 32] {
 
     let argon2 = Argon2::new(Algorithm::Argon2id, Version::V0x13, params);
 
-    let mut output_key = [0u8; 32];
+    let mut output_key = Zeroizing::new([0u8; 32]);
     argon2
-        .hash_password_into(password.as_bytes(), salt, &mut output_key)
+        .hash_password_into(password.as_bytes(), salt, &mut *output_key)
         .expect("Argon2id key derivation failed");
 
     output_key