lazaret/crates/lazaret-core/src/configuration/loading.rs

use super::confined_io::{
    config_home, confined_existing, data_home, ensure_owned_directory, expand_host_path, hex_lower,
    host_path, io_error, is_strict_descendant, paths_intersect, read_stable_configuration,
    require_clear_of_protected, require_pairwise_disjoint, require_pairwise_non_ancestral,
    require_strict_child_of_one, resolve_environment_references, resolve_environment_values,
    resolve_network, validate_configuration_stat, validate_executable, validate_host_base,
    validate_persistent_destinations,
};
use super::validation::{
    validate_profile_name, validate_sandbox_path, validate_structural_configuration, validate_text,
};
use super::{
    ConfigurationError, ConfigurationErrorKind, ConfigurationFingerprintRecordV1,
    ConfigurationLoadRequest, ConfinedPathPlan, ConfinedPathType, MAX_CONFIGURATION_BYTES, OFlags,
    OsStrExt, PathBuf, ResolvedAutoApproval, ResolvedAutoApprovalRule, ResolvedDomainConfiguration,
    ResolvedVolume, ResolvedVolumeAuthority, TrustedHostConfigurationV1, VolumeKind,
    derive_configuration_fingerprint, derive_domain_id,
};

/// Parses the closed trusted-host configuration document without resolving host authority.
///
/// # Errors
/// Unknown, duplicate, aliased, malformed, and unknown-version input is rejected.
pub fn parse_trusted_configuration(
    bytes: &[u8],
) -> Result<TrustedHostConfigurationV1, ConfigurationError> {
    if bytes.len() > MAX_CONFIGURATION_BYTES {
        return Err(ConfigurationError::new(
            ConfigurationErrorKind::InvalidConfigurationSource,
            "configuration exceeds 1,048,576 bytes",
        ));
    }
    let text = std::str::from_utf8(bytes).map_err(|_| {
        ConfigurationError::new(
            ConfigurationErrorKind::InvalidToml,
            "configuration is not UTF-8",
        )
    })?;
    let configuration: TrustedHostConfigurationV1 = toml::from_str(text).map_err(|error| {
        ConfigurationError::new(ConfigurationErrorKind::InvalidToml, error.to_string())
    })?;
    validate_structural_configuration(&configuration)?;
    Ok(configuration)
}

/// Resolves one selected profile into move-owned host authority.
///
/// # Errors
/// Loading fails atomically when source stability, strict syntax, confinement, environment,
/// network, volume, executable, or fingerprint validation fails.
#[allow(clippy::too_many_lines)]
pub fn load_trusted_configuration(
    request: ConfigurationLoadRequest,
) -> Result<ResolvedDomainConfiguration, ConfigurationError> {
    validate_host_base(&request.home, "HOME")?;
    validate_host_base(&request.xdg_runtime_dir, "XDG_RUNTIME_DIR")?;
    validate_profile_name(&request.selected_profile)?;

    let configuration_path = if let Some(explicit) = &request.explicit_configuration_path {
        let declaration = explicit.as_os_str().to_str().ok_or_else(|| {
            ConfigurationError::new(
                ConfigurationErrorKind::InvalidHostInput,
                "configuration path is not UTF-8",
            )
        })?;
        expand_host_path(declaration, &request.home, None)?
    } else {
        config_home(&request).join("lazaret/config.toml")
    };
    if request.explicit_configuration_path.is_none() {
        validate_host_base(&configuration_path, "configuration path")?;
    }
    let configuration_canonical = std::fs::canonicalize(&configuration_path).map_err(io_error)?;
    let configuration_source = ConfinedPathPlan::for_canonical_path(
        &configuration_canonical,
        ConfinedPathType::RegularFile,
    )?;
    let configuration_bytes = read_stable_configuration(&configuration_source)?;
    let configuration = parse_trusted_configuration(&configuration_bytes)?;
    let selected = configuration
        .profiles()
        .get(&request.selected_profile)
        .ok_or_else(|| {
            ConfigurationError::new(
                ConfigurationErrorKind::UnknownProfile,
                request.selected_profile.clone(),
            )
        })?;

    let workspace_canonical = std::fs::canonicalize(&request.workspace).map_err(io_error)?;
    let workspace = confined_existing(&workspace_canonical, ConfinedPathType::Directory, false)?;
    let workspace_bytes = workspace_canonical.as_os_str().as_bytes();
    let domain_id = derive_domain_id(&request.selected_profile, workspace_bytes)?;

    let data_root_declaration = configuration.storage().data_root.as_deref();
    let storage_path = match data_root_declaration {
        Some(declaration) => expand_host_path(declaration, &request.home, None)?,
        None => data_home(&request).join("lazaret"),
    };
    let runtime_path = request.xdg_runtime_dir.join("lazaret");
    let invoking_uid = rustix::process::getuid().as_raw();
    let storage_canonical = ensure_owned_directory(&storage_path, invoking_uid)?;
    let runtime_canonical = ensure_owned_directory(&runtime_path, invoking_uid)?;
    let profile_path = storage_canonical
        .join("profiles")
        .join(&request.selected_profile);
    let profile_canonical = ensure_owned_directory(&profile_path, invoking_uid)?;
    let domain_hex = hex_lower(domain_id.as_bytes());
    let persistent_domain_canonical = ensure_owned_directory(
        &storage_canonical.join("domains").join(&domain_hex),
        invoking_uid,
    )?;
    let runtime_domain_canonical = ensure_owned_directory(
        &runtime_canonical.join("domains").join(&domain_hex),
        invoking_uid,
    )?;

    let storage_root = confined_existing(&storage_canonical, ConfinedPathType::Directory, false)?;
    let runtime_root = confined_existing(&runtime_canonical, ConfinedPathType::Directory, false)?;
    let profile_root = confined_existing(&profile_canonical, ConfinedPathType::Directory, false)?;
    let persistent_domain_root = confined_existing(
        &persistent_domain_canonical,
        ConfinedPathType::Directory,
        false,
    )?;
    let runtime_domain_root = confined_existing(
        &runtime_domain_canonical,
        ConfinedPathType::Directory,
        false,
    )?;

    let core_paths = [
        configuration_canonical.as_path(),
        workspace_canonical.as_path(),
        storage_canonical.as_path(),
        runtime_canonical.as_path(),
    ];
    let core_authorities = [
        &configuration_source,
        &workspace,
        &storage_root,
        &runtime_root,
    ];
    require_pairwise_disjoint(
        &core_paths,
        &core_authorities,
        ConfigurationErrorKind::PathConflict,
    )?;

    let persistent_dirs = validate_persistent_destinations(
        &selected.persistent_dirs,
        request.sandbox_layout.protected_destinations(),
        request.sandbox_layout.nested_transient_overrides(),
    )?;
    let (effective_allow_prefixes, effective_deny_prefixes) =
        resolve_network(&configuration, selected)?;
    let environment_references = resolve_environment_references(selected)?;

    let mut volumes = Vec::with_capacity(selected.volumes.len());
    let mut resolved_volume_records = Vec::with_capacity(selected.volumes.len());
    let mut volume_paths: Vec<PathBuf> = Vec::with_capacity(selected.volumes.len());
    for volume in &selected.volumes {
        validate_sandbox_path(&volume.container)?;
        require_strict_child_of_one(&volume.container, &persistent_dirs)?;
        require_clear_of_protected(
            &volume.container,
            request.sandbox_layout.protected_destinations(),
        )?;
        let under_profile = volume.host.starts_with("{profile_dir}/");
        if volume.create && (volume.kind != VolumeKind::Directory || !under_profile) {
            return Err(ConfigurationError::new(
                ConfigurationErrorKind::InvalidVolume,
                "create=true requires a directory strictly beneath {profile_dir}",
            ));
        }
        let source_path = expand_host_path(&volume.host, &request.home, Some(&profile_canonical))?;
        let canonical = if volume.create {
            ensure_owned_directory(&source_path, invoking_uid)?
        } else {
            std::fs::canonicalize(&source_path).map_err(io_error)?
        };
        if !volume.create && canonical.as_os_str().as_bytes() != source_path.as_os_str().as_bytes()
        {
            return Err(ConfigurationError::new(
                ConfigurationErrorKind::InvalidVolume,
                "volume source contains a symlink",
            ));
        }
        let expected = match volume.kind {
            VolumeKind::File => ConfinedPathType::RegularFile,
            VolumeKind::Directory => ConfinedPathType::Directory,
        };
        let source_plan = confined_existing(&canonical, expected, false)?;
        for (forbidden, forbidden_authority) in core_paths.iter().zip(core_authorities) {
            if paths_intersect(&canonical, forbidden) {
                let allowed_profile_child = under_profile
                    && *forbidden == storage_canonical.as_path()
                    && is_strict_descendant(&canonical, &profile_canonical);
                if !allowed_profile_child {
                    return Err(ConfigurationError::new(
                        ConfigurationErrorKind::PathConflict,
                        "volume source intersects a protected host tree",
                    ));
                }
            }
            if source_plan.aliases(forbidden_authority) {
                return Err(ConfigurationError::new(
                    ConfigurationErrorKind::PathConflict,
                    "volume source aliases a protected host authority",
                ));
            }
        }
        if volume_paths
            .iter()
            .any(|other| paths_intersect(&canonical, other))
            || volumes
                .iter()
                .any(|other: &ResolvedVolumeAuthority| source_plan.aliases(&other.source_plan))
        {
            return Err(ConfigurationError::new(
                ConfigurationErrorKind::PathConflict,
                "volume sources overlap",
            ));
        }
        let record = ResolvedVolume {
            canonical_host_source: host_path(&canonical),
            container_path: volume.container.clone(),
            kind: volume.kind,
            access: volume.access,
            create: volume.create,
        };
        volume_paths.push(canonical);
        resolved_volume_records.push(record.clone());
        volumes.push(ResolvedVolumeAuthority {
            record,
            source_plan,
        });
    }
    require_pairwise_non_ancestral(
        selected
            .volumes
            .iter()
            .map(|volume| volume.container.as_str()),
        ConfigurationErrorKind::InvalidVolume,
    )?;

    let mut auto_approval_rules = Vec::new();
    let mut resolved_auto_approval_records = Vec::new();
    if !selected.escalation.enabled && !selected.escalation.auto_approve.is_empty() {
        return Err(ConfigurationError::new(
            ConfigurationErrorKind::InvalidAutoApproval,
            "disabled escalation profile contains auto-approval rules",
        ));
    }
    for rule in &selected.escalation.auto_approve {
        validate_text(&rule.executable, "auto-approval executable")?;
        for argument in &rule.args {
            validate_text(argument, "auto-approval argument")?;
        }
        if rule.allow_extra_args && rule.args.is_empty() {
            return Err(ConfigurationError::new(
                ConfigurationErrorKind::InvalidAutoApproval,
                "allow_extra_args requires a nonempty configured prefix",
            ));
        }
        let executable_path = expand_host_path(&rule.executable, &request.home, None)?;
        let canonical = std::fs::canonicalize(&executable_path).map_err(io_error)?;
        if core_paths
            .iter()
            .copied()
            .chain(volume_paths.iter().map(PathBuf::as_path))
            .chain([
                profile_canonical.as_path(),
                persistent_domain_canonical.as_path(),
                runtime_domain_canonical.as_path(),
            ])
            .any(|forbidden| paths_intersect(&canonical, forbidden))
        {
            return Err(ConfigurationError::new(
                ConfigurationErrorKind::InvalidAutoApproval,
                "auto-approval executable intersects a writable or control tree",
            ));
        }
        let executable_plan = confined_existing(&canonical, ConfinedPathType::RegularFile, true)?;
        if core_authorities
            .iter()
            .copied()
            .chain([&profile_root, &persistent_domain_root, &runtime_domain_root])
            .any(|forbidden| executable_plan.aliases(forbidden))
            || volumes
                .iter()
                .any(|volume| executable_plan.aliases(&volume.source_plan))
        {
            return Err(ConfigurationError::new(
                ConfigurationErrorKind::InvalidAutoApproval,
                "auto-approval executable aliases a writable or control authority",
            ));
        }
        let executable = executable_plan.reopen_exact(OFlags::RDONLY | OFlags::NONBLOCK)?;
        validate_executable(&executable, invoking_uid)?;
        let record = ResolvedAutoApprovalRule {
            canonical_executable: host_path(&canonical),
            args: rule.args.clone(),
            allow_extra_args: rule.allow_extra_args,
        };
        if resolved_auto_approval_records.contains(&record) {
            return Err(ConfigurationError::new(
                ConfigurationErrorKind::InvalidAutoApproval,
                "duplicate normalized auto-approval rule",
            ));
        }
        resolved_auto_approval_records.push(record.clone());
        auto_approval_rules.push(ResolvedAutoApproval {
            record,
            executable_plan,
            invoking_uid,
        });
    }

    let configuration_descriptor = configuration_source.open_authority()?;
    validate_configuration_stat(&rustix::fs::fstat(&configuration_descriptor).map_err(io_error)?)?;
    for authority in [
        &workspace,
        &storage_root,
        &runtime_root,
        &profile_root,
        &persistent_domain_root,
        &runtime_domain_root,
    ] {
        drop(authority.open_authority()?);
    }
    for volume in &volumes {
        drop(volume.open_source()?);
    }
    for rule in &auto_approval_rules {
        let executable = rule
            .executable_plan
            .reopen_exact(OFlags::RDONLY | OFlags::NONBLOCK)?;
        validate_executable(&executable, invoking_uid)?;
    }

    let fingerprint_record = ConfigurationFingerprintRecordV1 {
        selected_profile: request.selected_profile.clone(),
        storage_root: host_path(&storage_canonical),
        runtime_root: host_path(&runtime_canonical),
        runsc_dcache: configuration.runtime().runsc_dcache,
        image: selected.image.clone(),
        isolate_gitignored: selected.isolate_gitignored,
        persistent_dirs,
        environment_references,
        volumes: resolved_volume_records,
        effective_allow_prefixes: effective_allow_prefixes
            .iter()
            .map(|prefix| (prefix.address, prefix.prefix_length))
            .collect(),
        effective_deny_prefixes: effective_deny_prefixes
            .iter()
            .map(|prefix| (prefix.address, prefix.prefix_length))
            .collect(),
        escalation_enabled: selected.escalation.enabled,
        auto_approval_rules: resolved_auto_approval_records,
    };
    let configuration_fingerprint = derive_configuration_fingerprint(&fingerprint_record)?;
    let ephemeral_environment = resolve_environment_values(
        &fingerprint_record.environment_references,
        &request.environment,
    )?;

    Ok(ResolvedDomainConfiguration {
        selected_profile: request.selected_profile,
        domain_id,
        configuration_fingerprint,
        fingerprint_record,
        effective_allow_prefixes,
        effective_deny_prefixes,
        ephemeral_environment,
        configuration_source,
        workspace,
        storage_root,
        runtime_root,
        profile_root,
        persistent_domain_root,
        runtime_domain_root,
        volumes,
        auto_approval_rules,
    })
}