kanidm_unixd/

kanidm_unixd.rs

#![deny(warnings)]
#![warn(unused_extern_crates)]
#![deny(clippy::todo)]
#![deny(clippy::unimplemented)]
#![deny(clippy::unwrap_used)]
#![deny(clippy::expect_used)]
#![deny(clippy::panic)]
#![deny(clippy::unreachable)]
#![deny(clippy::await_holding_lock)]
#![deny(clippy::needless_pass_by_value)]
#![deny(clippy::trivially_copy_pass_by_ref)]

use clap::{Arg, ArgAction, Command};
use futures::{SinkExt, StreamExt};
use kanidm_client::KanidmClientBuilder;
use kanidm_hsm_crypto::{
    provider::{BoxedDynTpm, SoftTpm, Tpm},
    AuthValue,
};
use kanidm_proto::constants::DEFAULT_CLIENT_CONFIG_PATH;
use kanidm_proto::internal::OperationError;
use kanidm_unix_common::constants::DEFAULT_CONFIG_PATH;
use kanidm_unix_common::json_codec::JsonCodec;
use kanidm_unix_common::unix_config::{HsmType, UnixdConfig};
use kanidm_unix_common::unix_passwd::EtcDb;
use kanidm_unix_common::unix_proto::{
    ClientRequest, ClientResponse, TaskRequest, TaskRequestFrame, TaskResponse,
};
use kanidm_unix_resolver::db::{Cache, Db};
use kanidm_unix_resolver::idprovider::interface::IdProvider;
use kanidm_unix_resolver::idprovider::kanidm::KanidmProvider;
use kanidm_unix_resolver::idprovider::system::SystemProvider;
use kanidm_unix_resolver::resolver::{AuthSession, Resolver};
use kanidm_utils_users::{get_current_gid, get_current_uid, get_effective_gid, get_effective_uid};
use libc::umask;
use lru::LruCache;
use sketching::tracing::span;
use sketching::tracing_forest::util::*;
use sketching::tracing_forest::{self, traits::*};
use std::collections::BTreeMap;
use std::error::Error;
use std::fs::metadata;
use std::io::Error as IoError;
use std::num::NonZeroUsize;
use std::os::unix::fs::MetadataExt;
use std::path::PathBuf;
use std::process::ExitCode;
use std::str::FromStr;
use std::sync::Arc;
use std::time::{Duration, SystemTime};
use time::OffsetDateTime;
use tokio::fs::File;
use tokio::io::AsyncReadExt; // for read_to_end()
use tokio::net::{UnixListener, UnixStream};
use tokio::sync::broadcast;
use tokio::sync::mpsc::{channel, Receiver, Sender};
use tokio::sync::oneshot;
use tokio_util::codec::Framed;

#[cfg(feature = "dhat-heap")]
#[global_allocator]
static ALLOC: dhat::Alloc = dhat::Alloc;

const DEFAULT_CONCURRENT_AUTH_SESSIONS: NonZeroUsize = NonZeroUsize::new(64)
    .expect("Invalid DEFAULT_CONCURRENT_AUTH_SESSIONS constant at compile time");
const REFRESH_DEBOUNCE_SIZE: NonZeroUsize =
    NonZeroUsize::new(16).expect("Invalid REFRESH_DEBOUNCE_SIZE constant at compile time");
const REFRESH_DEBOUNCE_WINDOW: Duration = Duration::from_secs(5);

struct AsyncTaskRequest {
    task_req: TaskRequest,
    task_chan: oneshot::Sender<()>,
}

fn rm_if_exist(p: &str) {
    debug!("Attempting to remove file {}", p);
    let _ = std::fs::remove_file(p).map_err(|e| match e.kind() {
        std::io::ErrorKind::NotFound => {
            debug!("{} not present, no need to remove.", p);
        }
        _ => {
            error!(
                "Failure while attempting to attempting to remove {} -> {}",
                p,
                e.to_string()
            );
        }
    });
}

async fn handle_task_client(
    stream: UnixStream,
    notify_shadow_change_tx: &Sender<EtcDb>,
    task_channel_rx: &mut Receiver<AsyncTaskRequest>,
    broadcast_rx: &mut broadcast::Receiver<bool>,
) -> Result<(), Box<dyn Error>> {
    // setup the codec, this is to the unix socket which the task daemon
    // connected to us with.
    let mut last_task_id: u64 = 0;
    let mut task_handles: BTreeMap<u64, oneshot::Sender<()>> = BTreeMap::new();

    let codec: JsonCodec<TaskResponse, TaskRequestFrame> = JsonCodec::default();

    let mut framed_stream = Framed::new(stream, codec);

    loop {
        tokio::select! {
            biased; // tell tokio to poll these in order
            // We have been commanded to stop operation.
            _ = broadcast_rx.recv() => {
                return Ok(())
            }
            // We bias to *reading* messages in the resolver.
            response = framed_stream.next() => {
                // Process incoming messages. They may be out of order.
                match response {
                    Some(Ok(TaskResponse::Success(task_id))) => {
                        debug!("Task was acknowledged and completed.");

                        if let Some(handle) = task_handles.remove(&task_id) {
                            // Send a result back via the one-shot
                            // Ignore if it fails.
                            let _ = handle.send(());
                        }
                        // If the ID was unregistered, ignore.
                    }
                    Some(Ok(TaskResponse::NotifyShadowChange(etc_db))) => {
                        let _ = notify_shadow_change_tx.send(etc_db).await;
                    }
                    // Other things ....
                    // Some(Ok(TaskResponse::ReloadSystemIds))

                    other => {
                        error!("Error -> {:?}", other);
                        return Err(Box::new(IoError::other("oh no!")));
                    }
                }
            }
            task_request = task_channel_rx.recv() => {
                let Some(AsyncTaskRequest {
                    task_req,
                    task_chan
                }) = task_request else {
                    // Task channel has died, cease operation.
                    return Ok(())
                };

                debug!("Sending Task -> {:?}", task_req);

                last_task_id += 1;
                let task_id = last_task_id;

                // Setup the task handle so we know who to get back to.
                task_handles.insert(task_id, task_chan);

                let task_frame = TaskRequestFrame {
                    id: task_id,
                    req: task_req,
                };

                if let Err(err) = framed_stream.send(task_frame).await {
                    warn!("Unable to queue task for completion");
                    return Err(Box::new(err));
                }
                // Task sent
            }
        }
    }
}

async fn handle_client(
    sock: UnixStream,
    cachelayer: Arc<Resolver>,
    task_channel_tx: &Sender<AsyncTaskRequest>,
) {
    let conn_id = uuid::Uuid::new_v4();

    let Ok(ucred) = sock.peer_cred() else {
        error!("Unable to verify peer credentials, terminating connection.");
        return;
    };

    let codec: JsonCodec<ClientRequest, ClientResponse> = JsonCodec::default();

    let mut reqs = Framed::new(sock, codec);
    let mut session_id_counter: u64 = 1;
    let mut pam_auth_session_state: LruCache<u64, AuthSession> =
        LruCache::new(DEFAULT_CONCURRENT_AUTH_SESSIONS);

    // Setup a broadcast channel so that if we have an unexpected disconnection, we can
    // tell consumers to stop work.
    let (shutdown_tx, _shutdown_rx) = broadcast::channel(1);

    while let Some(Ok(req)) = reqs.next().await {
        let maybe_err: Result<(), Box<dyn Error>> = async {
            debug!(uid = ?ucred.uid(), gid = ?ucred.gid(), pid = ?ucred.pid());

            let resp = match req {
                ClientRequest::SshKey(account_id) => cachelayer
                    .get_sshkeys(account_id.as_str())
                    .await
                    .map(ClientResponse::SshKeys)
                    .unwrap_or_else(|_| {
                        error!("unable to load keys, returning empty set.");
                        ClientResponse::SshKeys(vec![])
                    }),
                ClientRequest::NssAccounts => cachelayer
                    .get_nssaccounts()
                    .await
                    .map(ClientResponse::NssAccounts)
                    .unwrap_or_else(|_| {
                        error!("unable to enum accounts");
                        ClientResponse::NssAccounts(Vec::new())
                    }),
                ClientRequest::NssAccountByUid(gid) => cachelayer
                    .get_nssaccount_gid(gid)
                    .await
                    .map(ClientResponse::NssAccount)
                    .unwrap_or_else(|_| {
                        error!("unable to load account, returning empty.");
                        ClientResponse::NssAccount(None)
                    }),
                ClientRequest::NssAccountByName(account_id) => cachelayer
                    .get_nssaccount_name(account_id.as_str())
                    .await
                    .map(ClientResponse::NssAccount)
                    .unwrap_or_else(|_| {
                        error!("unable to load account, returning empty.");
                        ClientResponse::NssAccount(None)
                    }),
                ClientRequest::NssGroups => cachelayer
                    .get_nssgroups()
                    .await
                    .map(ClientResponse::NssGroups)
                    .unwrap_or_else(|_| {
                        error!("unable to enum groups");
                        ClientResponse::NssGroups(Vec::new())
                    }),
                ClientRequest::NssGroupByGid(gid) => cachelayer
                    .get_nssgroup_gid(gid)
                    .await
                    .map(ClientResponse::NssGroup)
                    .unwrap_or_else(|_| {
                        error!("unable to load group, returning empty.");
                        ClientResponse::NssGroup(None)
                    }),
                ClientRequest::NssGroupByName(grp_id) => cachelayer
                    .get_nssgroup_name(grp_id.as_str())
                    .await
                    .map(ClientResponse::NssGroup)
                    .unwrap_or_else(|_| {
                        error!("unable to load group, returning empty.");
                        ClientResponse::NssGroup(None)
                    }),
                ClientRequest::PamAuthenticateInit { account_id, info } => {
                   #[allow(clippy::disallowed_methods)]
                    // Allowed as this is the time check for the remainder of the function and check.


                    let current_time = OffsetDateTime::now_utc();

                    match cachelayer
                        .pam_account_authenticate_init(
                            account_id.as_str(),
                            &info,
                            current_time,
                            shutdown_tx.subscribe(),
                        )
                        .await
                    {
                        Ok((auth_session, pam_auth_response)) => {

                            let session_id = session_id_counter;
                            session_id_counter += 1;

                            if pam_auth_session_state.push(session_id, auth_session).is_some() {
                                // Something really bad is up, stop everything.
                                pam_auth_session_state.clear();
                                error!("session_id was reused, unable to proceed. cancelling all inflight authentication sessions.");
                                ClientResponse::Error(OperationError::KU001InitWhileSessionActive)
                            } else {
                                ClientResponse::PamAuthenticateStepResponse {
                                    response: pam_auth_response,
                                    session_id,
                                }
                            }
                        }
                        Err(_) => ClientResponse::Error(OperationError::KU004PamInitFailed),
                    }
                }
                ClientRequest::PamAuthenticateStep {
                    request,
                    session_id,
                } => {
                    match pam_auth_session_state.get_mut(&session_id) {
                        Some(auth_session) => {
                            let response = cachelayer
                                .pam_account_authenticate_step(auth_session, request)
                                .await;

                            let is_complete = auth_session.is_complete();

                            // Release the reference so that we can manipulate the
                            // btreemap if needed
                            let _ = auth_session;

                            if let Ok(pam_auth_response) = response {
                                // What was the response? Is it a terminating case?
                                if is_complete {
                                    pam_auth_session_state.pop(&session_id);
                                }

                                ClientResponse::PamAuthenticateStepResponse {
                                    response: pam_auth_response,
                                    session_id,
                                }
                            } else {
                                ClientResponse::Error(OperationError::KU003PamAuthFailed)
                            }
                        }
                        None => {
                            error!("Attempt to continue auth session, but session id was not present. There may be too many concurrent authentication sessions in progress.");
                            ClientResponse::Error(OperationError::KU002ContinueWhileSessionInActive)
                        }
                    }

                }
                ClientRequest::PamAccountAllowed(account_id) => cachelayer
                    .pam_account_allowed(account_id.as_str())
                    .await
                    .map(ClientResponse::PamStatus)
                    .unwrap_or(ClientResponse::Error(
                        OperationError::KU005ErrorCheckingAccount,
                    )),
                ClientRequest::PamAccountBeginSession(account_id) => {
                    match cachelayer
                        .pam_account_beginsession(account_id.as_str())
                        .await
                    {
                        Ok(Some(info)) => {
                            let (tx, rx) = oneshot::channel();

                            match task_channel_tx
                                .send_timeout(
                                    AsyncTaskRequest {
                                        task_req: TaskRequest::HomeDirectory(info),
                                        task_chan: tx,
                                    },
                                    Duration::from_millis(100),
                                )
                                .await
                            {
                                Ok(()) => {
                                    // Now wait for the other end OR timeout.
                                    match tokio::time::timeout_at(
                                        tokio::time::Instant::now() + Duration::from_millis(1000),
                                        rx,
                                    )
                                    .await
                                    {
                                        Ok(Ok(_)) => {
                                            debug!("Task completed, returning to pam ...");
                                            ClientResponse::Ok
                                        }
                                        _ => {
                                            // Timeout or other error.
                                            ClientResponse::Error(OperationError::KG001TaskTimeout)
                                        }
                                    }
                                }
                                Err(_) => {
                                    // We could not submit the req. Move on!
                                    ClientResponse::Error(OperationError::KG002TaskCommFailure)
                                }
                            }
                        }
                        Ok(None) => {
                            // The session can begin, but we do not need to create the home dir.
                            ClientResponse::Ok
                        }
                        Err(_) => ClientResponse::Error(OperationError::KU005ErrorCheckingAccount),
                    }
                }
                ClientRequest::InvalidateCache => cachelayer
                    .invalidate()
                    .await
                    .map(|_| ClientResponse::Ok)
                    .unwrap_or(ClientResponse::Error(OperationError::KG003CacheClearFailed)),
                ClientRequest::ClearCache => {
                    if ucred.uid() == 0 {
                        cachelayer
                            .clear_cache()
                            .await
                            .map(|_| ClientResponse::Ok)
                            .unwrap_or(ClientResponse::Error(OperationError::KG003CacheClearFailed))
                    } else {
                        error!("{}", OperationError::KU006OnlyRootAllowed);
                        ClientResponse::Error(OperationError::KU006OnlyRootAllowed)
                    }
                }
                ClientRequest::Status => {
                    let status = cachelayer.provider_status().await;
                    ClientResponse::ProviderStatus(status)
                }
            };

            trace!(?resp);

            reqs.send(resp).await
                .inspect_err(|err| {
                    error!(?err, "unable to send response");
                })?;
            reqs.flush().await
                .inspect_err(|err| {
                    error!(?err, "unable to flush response");
                })?;

            trace!("flushed response!");

            Ok(())
        }
            .instrument(
                span!(Level::INFO, "client request", uuid = %conn_id, defer = true)
            )
            .await;

        if maybe_err.is_err() {
            break;
        }
    }

    // Disconnect them
    // Signal any tasks that they need to stop.
    if let Err(shutdown_err) = shutdown_tx.send(()) {
        warn!(
            ?shutdown_err,
            "Unable to signal tasks to stop, they will naturally timeout instead."
        )
    }
}

async fn read_hsm_pin(hsm_pin_path: &str) -> Result<Vec<u8>, Box<dyn Error>> {
    if !PathBuf::from_str(hsm_pin_path)?.exists() {
        return Err(std::io::Error::new(
            std::io::ErrorKind::NotFound,
            format!("HSM PIN file '{hsm_pin_path}' not found"),
        )
        .into());
    }

    let mut file = File::open(hsm_pin_path).await?;
    let mut contents = vec![];
    file.read_to_end(&mut contents).await?;
    Ok(contents)
}

async fn write_hsm_pin(hsm_pin_path: &str) -> Result<(), Box<dyn Error>> {
    if !PathBuf::from_str(hsm_pin_path)?.exists() {
        let new_pin = AuthValue::generate().map_err(|hsm_err| {
            error!(?hsm_err, "Unable to generate new pin");
            std::io::Error::other("Unable to generate new pin")
        })?;

        std::fs::write(hsm_pin_path, new_pin)?;

        info!("Generated new HSM pin");
    }

    Ok(())
}

#[cfg(feature = "tpm")]
fn open_tpm(tcti_name: &str) -> Option<BoxedDynTpm> {
    use kanidm_hsm_crypto::provider::TssTpm;
    match TssTpm::new(tcti_name) {
        Ok(tpm) => {
            debug!("opened hw tpm");
            Some(BoxedDynTpm::new(tpm))
        }
        Err(tpm_err) => {
            error!(?tpm_err, "Unable to open requested tpm device");
            None
        }
    }
}

#[cfg(not(feature = "tpm"))]
fn open_tpm(_tcti_name: &str) -> Option<BoxedDynTpm> {
    error!("Hardware TPM supported was not enabled in this build. Unable to proceed");
    None
}

#[cfg(feature = "tpm")]
fn open_tpm_if_possible(tcti_name: &str) -> BoxedDynTpm {
    use kanidm_hsm_crypto::provider::TssTpm;
    match TssTpm::new(tcti_name) {
        Ok(tpm) => {
            debug!("opened hw tpm");
            BoxedDynTpm::new(tpm)
        }
        Err(tpm_err) => {
            warn!(
                ?tpm_err,
                "Unable to open requested tpm device, falling back to soft tpm"
            );
            BoxedDynTpm::new(SoftTpm::new())
        }
    }
}

#[cfg(not(feature = "tpm"))]
fn open_tpm_if_possible(_tcti_name: &str) -> BoxedDynTpm {
    debug!("opened soft tpm");
    BoxedDynTpm::new(SoftTpm::default())
}

async fn main_inner(clap_args: clap::ArgMatches) -> ExitCode {
    let cuid = get_current_uid();
    let ceuid = get_effective_uid();
    let cgid = get_current_gid();
    let cegid = get_effective_gid();

    if clap_args.get_flag("skip-root-check") {
        warn!("Skipping root user check, if you're running this for testing, ensure you clean up temporary files.")
        // TODO: this wording is not great m'kay.
    } else if cuid == 0 || ceuid == 0 || cgid == 0 || cegid == 0 {
        error!("Refusing to run - this process must not operate as root.");
        return ExitCode::FAILURE;
    };

    debug!("Profile -> {}", env!("KANIDM_PROFILE_NAME"));
    debug!("CPU Flags -> {}", env!("KANIDM_CPU_FLAGS"));

    let Some(cfg_path_str) = clap_args.get_one::<String>("client-config") else {
        error!("Failed to pull the client config path");
        return ExitCode::FAILURE;
    };
    let cfg_path: PathBuf = PathBuf::from(cfg_path_str);

    if !cfg_path.exists() {
        // there's no point trying to start up if we can't read a usable config!
        error!(
            "Client config missing from {} - cannot start up. Quitting.",
            cfg_path_str
        );
        let diag = kanidm_lib_file_permissions::diagnose_path(cfg_path.as_ref());
        info!(%diag);
        return ExitCode::FAILURE;
    } else {
        let cfg_meta = match metadata(&cfg_path) {
            Ok(v) => v,
            Err(e) => {
                error!("Unable to read metadata for {} - {:?}", cfg_path_str, e);
                let diag = kanidm_lib_file_permissions::diagnose_path(cfg_path.as_ref());
                info!(%diag);
                return ExitCode::FAILURE;
            }
        };
        if !kanidm_lib_file_permissions::readonly(&cfg_meta) {
            warn!("permissions on {} may not be secure. Should be readonly to running uid. This could be a security risk ...",
                        cfg_path_str
                        );
        }

        if cfg_meta.uid() == cuid || cfg_meta.uid() == ceuid {
            warn!("WARNING: {} owned by the current uid, which may allow file permission changes. This could be a security risk ...",
                        cfg_path_str
                    );
        }
    }

    let Some(unixd_path_str) = clap_args.get_one::<String>("unixd-config") else {
        error!("Failed to pull the unixd config path");
        return ExitCode::FAILURE;
    };
    let unixd_path = PathBuf::from(unixd_path_str);

    if !unixd_path.exists() {
        // there's no point trying to start up if we can't read a usable config!
        error!(
            "unixd config missing from {} - cannot start up. Quitting.",
            unixd_path_str
        );
        let diag = kanidm_lib_file_permissions::diagnose_path(unixd_path.as_ref());
        info!(%diag);
        return ExitCode::FAILURE;
    } else {
        let unixd_meta = match metadata(&unixd_path) {
            Ok(v) => v,
            Err(e) => {
                error!("Unable to read metadata for {} - {:?}", unixd_path_str, e);
                let diag = kanidm_lib_file_permissions::diagnose_path(unixd_path.as_ref());
                info!(%diag);
                return ExitCode::FAILURE;
            }
        };
        if !kanidm_lib_file_permissions::readonly(&unixd_meta) {
            warn!("permissions on {} may not be secure. Should be readonly to running uid. This could be a security risk ...",
                        unixd_path_str);
        }

        if unixd_meta.uid() == cuid || unixd_meta.uid() == ceuid {
            warn!("WARNING: {} owned by the current uid, which may allow file permission changes. This could be a security risk ...",
                        unixd_path_str
                    );
        }
    }

    let cfg = match UnixdConfig::new().read_options_from_optional_config(&unixd_path) {
        Ok(v) => v,
        Err(_) => {
            error!("Failed to parse {}", unixd_path_str);
            return ExitCode::FAILURE;
        }
    };

    let client_builder = if let Some(kconfig) = &cfg.kanidm_config {
        if kconfig.pam_allowed_login_groups.is_empty() {
            error!("Kanidm is enabled but no pam_allowed_login_groups are set - KANIDM USERS CANNOT AUTHENTICATE !!!");
        }

        // setup
        let cb = match KanidmClientBuilder::new().read_options_from_optional_config(&cfg_path) {
            Ok(v) => v,
            Err(_) => {
                error!("Failed to parse {}", cfg_path_str);
                return ExitCode::FAILURE;
            }
        };

        Some((cb, kconfig))
    } else {
        None
    };

    if clap_args.get_flag("configtest") {
        eprintln!("###################################");
        eprintln!("Dumping configs:\n###################################");
        eprintln!("kanidm_unixd config (from {:#?})", &unixd_path);
        eprintln!("{cfg}");
        eprintln!("###################################");
        if let Some((cb, _)) = client_builder.as_ref() {
            eprintln!("kanidm client config (from {:#?})", &cfg_path);
            eprintln!("{cb}");
        } else {
            eprintln!("kanidm client: disabled");
        }
        return ExitCode::SUCCESS;
    }

    debug!("🧹 Cleaning up sockets from previous invocations");
    rm_if_exist(&cfg.sock_path);
    rm_if_exist(&cfg.task_sock_path);

    // Check the db path will be okay.
    if !cfg.cache_db_path.is_empty() {
        let cache_db_path = PathBuf::from(cfg.cache_db_path.as_str());
        // We only need to check the parent folder path permissions as the db itself may not exist yet.
        if let Some(db_parent_path) = cache_db_path.parent() {
            if !db_parent_path.exists() {
                error!(
                    "Refusing to run, DB folder {} does not exist",
                    db_parent_path
                        .to_str()
                        .unwrap_or("<db_parent_path invalid>")
                );
                let diag = kanidm_lib_file_permissions::diagnose_path(cache_db_path.as_ref());
                info!(%diag);
                return ExitCode::FAILURE;
            }

            let db_par_path_buf = db_parent_path.to_path_buf();

            let i_meta = match metadata(&db_par_path_buf) {
                Ok(v) => v,
                Err(e) => {
                    error!(
                        "Unable to read metadata for {} - {:?}",
                        db_par_path_buf
                            .to_str()
                            .unwrap_or("<db_par_path_buf invalid>"),
                        e
                    );
                    return ExitCode::FAILURE;
                }
            };

            if !i_meta.is_dir() {
                error!(
                    "Refusing to run - DB folder {} may not be a directory",
                    db_par_path_buf
                        .to_str()
                        .unwrap_or("<db_par_path_buf invalid>")
                );
                return ExitCode::FAILURE;
            }
            if kanidm_lib_file_permissions::readonly(&i_meta) {
                warn!("WARNING: DB folder permissions on {} indicate it may not be RW. This could cause the server start up to fail!", db_par_path_buf.to_str()
                        .unwrap_or("<db_par_path_buf invalid>")
                        );
            }

            if i_meta.mode() & 0o007 != 0 {
                warn!("WARNING: DB folder {} has 'everyone' permission bits in the mode. This could be a security risk ...", db_par_path_buf.to_str()
                        .unwrap_or("<db_par_path_buf invalid>")
                        );
            }
        }

        // check to see if the db's already there
        if cache_db_path.exists() {
            if !cache_db_path.is_file() {
                error!(
                    "Refusing to run - DB path {} already exists and is not a file.",
                    cache_db_path.to_str().unwrap_or("<cache_db_path invalid>")
                );
                let diag = kanidm_lib_file_permissions::diagnose_path(cache_db_path.as_ref());
                info!(%diag);
                return ExitCode::FAILURE;
            };

            match metadata(&cache_db_path) {
                Ok(v) => v,
                Err(e) => {
                    error!(
                        "Unable to read metadata for {} - {:?}",
                        cache_db_path.to_str().unwrap_or("<cache_db_path invalid>"),
                        e
                    );
                    let diag = kanidm_lib_file_permissions::diagnose_path(cache_db_path.as_ref());
                    info!(%diag);
                    return ExitCode::FAILURE;
                }
            };
            // TODO: permissions dance to enumerate the user's ability to write to the file? ref #456 - r2d2 will happily keep trying to do things without bailing.
        };
    }

    let db = match Db::new(cfg.cache_db_path.as_str()) {
        Ok(db) => db,
        Err(_e) => {
            error!("Failed to create database");
            return ExitCode::FAILURE;
        }
    };

    // perform any db migrations.
    let mut dbtxn = db.write().await;
    if dbtxn.migrate().and_then(|_| dbtxn.commit()).is_err() {
        error!("Failed to migrate database");
        return ExitCode::FAILURE;
    }

    // Check for and create the hsm pin if required.
    if let Err(err) = write_hsm_pin(cfg.hsm_pin_path.as_str()).await {
        let diag = kanidm_lib_file_permissions::diagnose_path(cfg.hsm_pin_path.as_ref());
        info!(%diag);
        error!(
            ?err,
            "Failed to create HSM PIN into {}",
            cfg.hsm_pin_path.as_str()
        );
        return ExitCode::FAILURE;
    };

    // read the hsm pin
    let hsm_pin = match read_hsm_pin(cfg.hsm_pin_path.as_str()).await {
        Ok(hp) => hp,
        Err(err) => {
            let diag = kanidm_lib_file_permissions::diagnose_path(cfg.hsm_pin_path.as_ref());
            info!(%diag);
            error!(
                ?err,
                "Failed to read HSM PIN from {}",
                cfg.hsm_pin_path.as_str()
            );
            return ExitCode::FAILURE;
        }
    };

    let auth_value = match AuthValue::try_from(hsm_pin.as_slice()) {
        Ok(av) => av,
        Err(err) => {
            error!(?err, "invalid hsm pin");
            return ExitCode::FAILURE;
        }
    };

    let mut hsm: BoxedDynTpm = match cfg.hsm_type {
        HsmType::Soft => BoxedDynTpm::new(SoftTpm::default()),
        HsmType::TpmIfPossible => open_tpm_if_possible(&cfg.tpm_tcti_name),
        HsmType::Tpm => match open_tpm(&cfg.tpm_tcti_name) {
            Some(hsm) => hsm,
            None => return ExitCode::FAILURE,
        },
    };

    // With the assistance of the DB, setup the HSM and its machine key.
    let mut db_txn = db.write().await;

    let loadable_machine_key = match db_txn.get_hsm_root_storage_key() {
        Ok(Some(lmk)) => lmk,
        Ok(None) => {
            // No machine key found - create one, and store it.
            let loadable_machine_key = match hsm.root_storage_key_create(&auth_value) {
                Ok(lmk) => lmk,
                Err(err) => {
                    error!(?err, "Unable to create hsm loadable machine key");
                    return ExitCode::FAILURE;
                }
            };

            if let Err(err) = db_txn.insert_hsm_root_storage_key(&loadable_machine_key) {
                error!(?err, "Unable to persist hsm loadable machine key");
                return ExitCode::FAILURE;
            }

            loadable_machine_key
        }
        Err(err) => {
            error!(?err, "Unable to access hsm loadable machine key");
            return ExitCode::FAILURE;
        }
    };

    let machine_key = match hsm.root_storage_key_load(&auth_value, &loadable_machine_key) {
        Ok(mk) => mk,
        Err(err) => {
            error!(
                ?err,
                "Unable to load machine root key - This can occur if you have changed your HSM pin"
            );
            error!(
                "To proceed you must remove the content of the cache db ({}) to reset all keys",
                cfg.cache_db_path.as_str()
            );
            return ExitCode::FAILURE;
        }
    };

    let Ok(system_provider) = SystemProvider::new() else {
        error!("Failed to configure System Provider");
        return ExitCode::FAILURE;
    };

    info!("Started system provider");

    let mut clients: Vec<Arc<dyn IdProvider + Send + Sync>> = Vec::with_capacity(1);

    // Setup Kanidm provider if the configuration requests it.
    if let Some((cb, kconfig)) = client_builder {
        let cb = cb.connect_timeout(kconfig.conn_timeout);
        let cb = cb.request_timeout(kconfig.request_timeout);

        let rsclient = match cb.build() {
            Ok(rsc) => rsc,
            Err(_e) => {
                error!("Failed to build async client");
                return ExitCode::FAILURE;
            }
        };

        let Ok(idprovider) = KanidmProvider::new(
            rsclient,
            kconfig,
            SystemTime::now(),
            &mut (&mut db_txn).into(),
            &mut hsm,
            &machine_key,
        )
        .await
        else {
            error!("Failed to configure Kanidm Provider");
            return ExitCode::FAILURE;
        };

        // Now stacked for the resolver.
        clients.push(Arc::new(idprovider));
        info!("Started kanidm provider");
    }

    drop(machine_key);

    if let Err(err) = db_txn.commit() {
        error!(
            ?err,
            "Failed to commit database transaction, unable to proceed"
        );
        return ExitCode::FAILURE;
    }

    if !cfg.default_shell.is_empty() {
        let shell_path = PathBuf::from_str(&cfg.default_shell)
            .expect("Failed to build a representation of your default_shell path!");
        if !shell_path.exists() {
            error!(
                "Cannot find configured default shell at {}, this could cause login issues!",
                shell_path.display()
            )
        }
    }

    // Okay, the hsm is now loaded and ready to go.
    let (cl_inner, mut async_refresh_rx) = match Resolver::new(
        db,
        Arc::new(system_provider),
        clients,
        hsm,
        cfg.cache_timeout,
        cfg.default_shell.clone(),
        cfg.home_prefix.clone(),
        cfg.home_attr,
        cfg.home_alias,
        cfg.uid_attr_map,
        cfg.gid_attr_map,
    )
    .await
    {
        Ok(c) => c,
        Err(_e) => {
            error!("Failed to build cache layer.");
            return ExitCode::FAILURE;
        }
    };

    let cachelayer = Arc::new(cl_inner);

    // Setup the root-only tasks socket. Take away all other access bits.
    let before = unsafe { umask(0o0077) };
    let task_listener = match UnixListener::bind(cfg.task_sock_path.as_str()) {
        Ok(l) => l,
        Err(_e) => {
            let diag = kanidm_lib_file_permissions::diagnose_path(cfg.task_sock_path.as_ref());
            info!(%diag);
            error!("Failed to bind UNIX socket {}", cfg.task_sock_path.as_str());
            return ExitCode::FAILURE;
        }
    };
    // Undo umask changes.
    let _ = unsafe { umask(before) };

    // The tasks ... well task. Tasks-task. Anyway, the tasks-task is bidirectional
    // in its communication to the tasks-daemon. We submit tasks to the tasks-daemon
    // via this channel here -\
    //                        |
    //                        v
    let (task_channel_tx, mut task_channel_rx) = channel(16);
    let task_channel_tx = Arc::new(task_channel_tx);
    let task_channel_tx_cln = task_channel_tx.clone();
    // Each submitted task contains a oneshot channel allowing the tasks-task to
    // notify the submitter of the task that the task is completed.

    // This channel is for the second case - the tasks-daemon can send us
    // unsolicited dm's about system state, and when these occure we need to
    // response to these notifications. Because each potential dm that the
    // daemon can send us has a specific intent, we need a channel for each
    // type of notification that we could get. This channel is for when
    // the tasks daemon has a reloaded shadow database for us to process
    // and cache:
    let (notify_shadow_channel_tx, mut notify_shadow_channel_rx) = channel(16);
    let notify_shadow_channel_tx = Arc::new(notify_shadow_channel_tx);

    // Broadcast receivers so that the tasks-task can be shut down when we get
    // signals etc.
    let (broadcast_tx, mut broadcast_rx) = broadcast::channel(4);
    let mut c_broadcast_rx = broadcast_tx.subscribe();
    let mut d_broadcast_rx = broadcast_tx.subscribe();

    let task_b = tokio::spawn(async move {
        loop {
            tokio::select! {
                // Wait on the broadcast to see if we need to close down.
                _ = c_broadcast_rx.recv() => {
                    break;
                }
                accept_res = task_listener.accept() => {
                    match accept_res {
                        Ok((socket, _addr)) => {
                            // Did it come from root? If not, they don't have the needed
                            // permissions to actually be a task handler, and we wouldn't
                            // want to leak to anyone else anyway.
                            if let Ok(ucred) = socket.peer_cred() {
                                if ucred.uid() != 0 {
                                    // move along.
                                    warn!("Task handler not running as root, ignoring ...");
                                    continue;
                                }
                            } else {
                                // move along.
                                warn!("Unable to determine socked peer cred, ignoring ...");
                                continue;
                            };
                            debug!("A task handler has connected.");
                            // It did? Great, now we can wait and spin on that one
                            // client.

                            // We have to check for signals here else this tasks waits forever.
                            if let Err(err) = handle_task_client(socket, &notify_shadow_channel_tx, &mut task_channel_rx, &mut d_broadcast_rx).await {
                                error!(?err, "Task client error occurred");
                            }
                            // If they disconnect we go back to accept.
                        }
                        Err(err) => {
                            error!("Task Accept error -> {:?}", err);
                        }
                    }
                }
            }
            // done
        }
        info!("Stopped task connector");
    });

    // ====== Listen for shadow change notification from tasks ======

    let shadow_notify_cachelayer = cachelayer.clone();
    let mut c_broadcast_rx = broadcast_tx.subscribe();

    let task_c = tokio::spawn(async move {
        debug!("Spawned shadow reload task handler");
        loop {
            tokio::select! {
                _ = c_broadcast_rx.recv() => {
                    break;
                }
                Some(EtcDb {
                    users, shadow, groups
                }) = notify_shadow_channel_rx.recv() => {
                    shadow_notify_cachelayer
                        .reload_system_identities(users, shadow, groups)
                        .await;
                }
            }
        }
        info!("Stopped shadow reload task handler");
    });

    // Setup the task that handles async pre-fetching here.
    let prefetch_cachelayer = cachelayer.clone();
    let _task_prefetch = tokio::spawn(async move {
        let mut refresh_cache = LruCache::new(REFRESH_DEBOUNCE_SIZE);

        while let Some(refresh_account_id) = async_refresh_rx.recv().await {
            let current_time = SystemTime::now();

            // Have we already checked this item in the last few seconds?
            match refresh_cache.get(&refresh_account_id).copied() {
                Some(not_before) if current_time < not_before => {
                    debug!(?refresh_account_id, "debounce triggered");
                    continue;
                }
                _ => {}
            };

            // Mark that we are about to refresh this, and that we shouldn't attempt again for a few seconds.
            refresh_cache.put(
                refresh_account_id.clone(),
                current_time + REFRESH_DEBOUNCE_WINDOW,
            );

            // we don't mind if there was an error, it's already logged, and on success
            // we don't need the info anyway.
            if prefetch_cachelayer
                .refresh_usertoken(&refresh_account_id, current_time)
                .await
                .is_ok()
            {
                debug!(?refresh_account_id, "successful refresh of account");
            } else {
                warn!(?refresh_account_id, "failed to refresh account");
            }
        }
    });

    // Set the umask while we open the path for most clients.
    let before = unsafe { umask(0) };
    let listener = match UnixListener::bind(cfg.sock_path.as_str()) {
        Ok(l) => l,
        Err(_e) => {
            error!("Failed to bind UNIX socket at {}", cfg.sock_path.as_str());
            return ExitCode::FAILURE;
        }
    };
    // Undo umask changes.
    let _ = unsafe { umask(before) };

    let task_a = tokio::spawn(async move {
        loop {
            let tc_tx = task_channel_tx_cln.clone();

            tokio::select! {
                _ = broadcast_rx.recv() => {
                    break;
                }
                accept_res = listener.accept() => {
                    match accept_res {
                        Ok((socket, _addr)) => {
                            let cachelayer_ref = cachelayer.clone();
                            tokio::spawn(async move {
                                handle_client(socket, cachelayer_ref.clone(), &tc_tx).await;
                            });
                        }
                        Err(err) => {
                            error!(?err, "Error while accepting connection");
                        }
                    }
                }
            }
        }
        info!("Stopped resolver");
    });

    info!("Server started ...");

    // On linux, notify systemd.
    #[cfg(target_os = "linux")]
    let _ = sd_notify::notify(true, &[sd_notify::NotifyState::Ready]);

    loop {
        tokio::select! {
            Ok(()) = tokio::signal::ctrl_c() => {
                break
            }
            Some(()) = async move {
                let sigterm = tokio::signal::unix::SignalKind::terminate();
                #[allow(clippy::unwrap_used)]
                tokio::signal::unix::signal(sigterm).unwrap().recv().await
            } => {
                break
            }
            Some(()) = async move {
                let sigterm = tokio::signal::unix::SignalKind::alarm();
                #[allow(clippy::unwrap_used)]
                tokio::signal::unix::signal(sigterm).unwrap().recv().await
            } => {
                // Ignore
            }
            Some(()) = async move {
                let sigterm = tokio::signal::unix::SignalKind::hangup();
                #[allow(clippy::unwrap_used)]
                tokio::signal::unix::signal(sigterm).unwrap().recv().await
            } => {
                // Ignore
            }
            Some(()) = async move {
                let sigterm = tokio::signal::unix::SignalKind::user_defined1();
                #[allow(clippy::unwrap_used)]
                tokio::signal::unix::signal(sigterm).unwrap().recv().await
            } => {
                // Ignore
            }
            Some(()) = async move {
                let sigterm = tokio::signal::unix::SignalKind::user_defined2();
                #[allow(clippy::unwrap_used)]
                tokio::signal::unix::signal(sigterm).unwrap().recv().await
            } => {
                // Ignore
            }
        }
    }
    info!("Signal received, sending down signal to tasks");
    // Send a broadcast that we are done.
    if let Err(e) = broadcast_tx.send(true) {
        error!("Unable to shutdown workers {:?}", e);
    }

    let _ = task_a.await;
    let _ = task_b.await;
    let _ = task_c.await;

    ExitCode::SUCCESS
}

// #[tokio::main(flavor = "current_thread")]
#[tokio::main(flavor = "multi_thread", worker_threads = 2)]
async fn main() -> ExitCode {
    // On linux when debug assertions are disabled, prevent ptrace
    // from attaching to us.
    #[cfg(all(target_os = "linux", not(debug_assertions)))]
    if let Err(code) = prctl::set_dumpable(false) {
        error!(?code, "CRITICAL: Unable to set prctl flags");
        return ExitCode::FAILURE;
    }

    // We need enough backtrace depth to find leak sources if they exist.
    #[cfg(feature = "dhat-heap")]
    let _profiler = dhat::Profiler::builder()
        .file_name(format!(
            "/var/cache/kanidm-unixd/heap-{}.json",
            std::process::id()
        ))
        .trim_backtraces(Some(40))
        .build();

    let clap_args = Command::new("kanidm_unixd")
        .version(env!("CARGO_PKG_VERSION"))
        .about("Kanidm Unix daemon")
        .arg(
            Arg::new("skip-root-check")
                .help("Allow running as root. Don't use this in production as it is risky!")
                .short('r')
                .long("skip-root-check")
                .env("KANIDM_SKIP_ROOT_CHECK")
                .action(ArgAction::SetTrue),
        )
        .arg(
            Arg::new("debug")
                .help("Show extra debug information")
                .short('d')
                .long("debug")
                .env("KANIDM_DEBUG")
                .action(ArgAction::SetTrue),
        )
        .arg(
            Arg::new("configtest")
                .help("Display the configuration and exit")
                .short('t')
                .long("configtest")
                .action(ArgAction::SetTrue),
        )
        .arg(
            Arg::new("unixd-config")
                .help("Set the unixd config file path")
                .short('u')
                .long("unixd-config")
                .default_value(DEFAULT_CONFIG_PATH)
                .env("KANIDM_UNIX_CONFIG")
                .action(ArgAction::Set),
        )
        .arg(
            Arg::new("client-config")
                .help("Set the client config file path")
                .short('c')
                .long("client-config")
                .default_value(DEFAULT_CLIENT_CONFIG_PATH)
                .env("KANIDM_CLIENT_CONFIG")
                .action(ArgAction::Set),
        )
        .get_matches();

    if clap_args.get_flag("debug") {
        std::env::set_var("RUST_LOG", "debug");
    }

    #[allow(clippy::expect_used)]
    tracing_forest::worker_task()
        .set_global(true)
        // Fall back to stderr
        .map_sender(|sender| sender.or_stderr())
        .build_on(|subscriber| {
            subscriber.with(
                EnvFilter::try_from_default_env()
                    .or_else(|_| EnvFilter::try_new("info"))
                    .expect("Failed to init envfilter"),
            )
        })
        .on(main_inner(clap_args))
        .await
}