harn-vm 0.10.168

//! Public re-exports of the platform-specific process sandbox primitives.
//!
//! Embedders that spawn subprocesses on behalf of Harn scripts (today: the
//! `harn-hostlib` deterministic-tool builtins) must funnel every spawn
//! through these helpers so the active orchestration capability policy is
//! enforced — Linux seccomp/landlock filters via `pre_exec`, macOS
//! `sandbox-exec` wrapping, no OS confinement on Windows (a warning, or a
//! refusal under `os_hardened`), plus workspace-root cwd enforcement.
//!
//! The same surface also exposes [`check_fs_path_scope`] so embedders that
//! resolve host *paths* on behalf of Harn scripts (the `harn-hostlib`
//! `fs/*`, `tools/*`, and `ast/*` builtins) can enforce the active policy's
//! workspace-root scope without depending on `VmError`.
//!
//! The helpers themselves live next to the rest of the sandbox state in
//! [`crate::stdlib::sandbox`]. This module exists so external crates have a
//! stable, documented surface to depend on without reaching into
//! `stdlib::*` plumbing.

pub use crate::stdlib::sandbox::{
    active_backend_available, active_backend_filesystem_available,
    active_backend_filesystem_mechanism, active_backend_mechanism, active_backend_mechanism_limits,
    active_backend_name, active_workspace_process_env, apply_active_rustc_wrapper_policy,
    apply_active_rustc_wrapper_policy_for_command, check_fs_path_scope,
    check_git_metadata_path_scope, command_output, conformance, deterministic_message_locale_env,
    enforce_process_cwd, enforcement, host_confinement, infer_process_sandbox_mechanism,
    is_process_sandbox_signal, is_workspace_runtime_directory, process_spawn_error,
    process_violation_error, push_process_sandbox_scope, render_policy_root, rustc_wrapper,
    session_std_command, session_tokio_command, std_command_for, std_command_for_with_env_state,
    tokio_command_for, tokio_command_for_with_env_state, validate_command_environment,
    workspace_local_tmpdir, FsAccess, ProcessCommandConfig, ProcessSandboxAssessment,
    ProcessSandboxDenialReporting, ProcessSandboxGrants, ProcessSandboxMechanism,
    ProcessSandboxOperation, ProcessSandboxRefusal, ProcessSandboxReportingContext,
    ProcessSandboxScope, ProcessSandboxScopeGuard, SandboxMechanism, SandboxMechanismAvailability,
    SandboxMechanismUnavailable, SandboxRequirement, SandboxViolation, MESSAGE_LOCALE_OVERRIDE_ENV,
    SANDBOX_CONFINEMENT_SCHEMA,
};

pub use crate::stdlib::git_topology::check_repository_metadata_scope;
pub use crate::stdlib::sandbox::command_output_with_declared_roots;

impl ProcessSandboxScope {
    /// Parse the shared per-command workspace scope at the process boundary.
    pub fn from_value(value: Option<&crate::VmValue>) -> Result<Self, crate::VmError> {
        use crate::VmValue;
        let invalid = |message: String| crate::VmError::TypeError(format!("sandbox: {message}"));
        let map = match value {
            None | Some(VmValue::Nil) => return Ok(Self::default()),
            Some(VmValue::Dict(map)) => map,
            Some(other) => {
                return Err(invalid(format!("expected dict, got {}", other.type_name())))
            }
        };
        let roots = match map.get("workspace_roots") {
            None | Some(VmValue::Nil) => return Ok(Self::default()),
            Some(VmValue::List(roots)) => roots,
            Some(other) => {
                return Err(invalid(format!(
                    "workspace_roots must be a list of strings, got {}",
                    other.type_name()
                )))
            }
        };
        let workspace_roots = roots
            .iter()
            .map(|root| match root {
                VmValue::String(root) if !root.trim().is_empty() => Ok(root.to_string()),
                _ => Err(invalid(
                    "workspace_roots entries must be nonempty strings".into(),
                )),
            })
            .collect::<Result<Vec<_>, _>>()?;
        Ok(Self { workspace_roots })
    }
}

/// Confine the running process, not a child, under a capability policy. An
/// agent server calls this once before it serves; see the module for what a
/// confined process's children inherit on each platform.
pub use crate::stdlib::sandbox::self_confinement::{
    confine_current_process, current_process_confinement, ProcessConfinement,
};

/// The subcommand the namespace helper is invoked as, and the flags that
/// carry the confinement to it.
///
/// One definition, read by both sides of the handover. The Linux backend
/// builds the argv from these and the CLI recognises and parses it with the
/// same names, so the two cannot drift into a helper that is spawned but
/// never dispatched. They are platform-neutral because the command surface
/// that declares the subcommand is compiled on every platform, while the
/// backend that invokes it is not.
///
/// A subcommand of this same runtime rather than a separate program: the host
/// policy grant names an installed *copy* at a stable path, and a copy of one
/// binary is cheaper to keep at the pinned revision than a second artifact
/// with its own build and release story.
pub const NETNS_LAUNCH_SUBCOMMAND: &str = "netns-launch";

/// Flag naming the inherited Landlock ruleset descriptor.
pub const NETNS_RULESET_FD_FLAG: &str = "--ruleset-fd";

/// Flag carrying the compiled seccomp program, hex-encoded.
pub const NETNS_SECCOMP_FLAG: &str = "--seccomp-hex";

/// Inherited setup descriptor to close before an already-confined payload exec.
pub const NETNS_CLOSE_FD_FLAG: &str = "--close-fd";

/// One device source whose mounted identity must hold before payload exec.
/// The argument contract exists on every CLI platform; Linux executes it.
#[derive(Clone, Debug)]
pub struct DeviceMountFinalization {
    pub descriptor: i32,
    pub destination: std::path::PathBuf,
}

impl std::fmt::Display for DeviceMountFinalization {
    fn fmt(&self, out: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(out, "{}:{}", self.descriptor, self.destination.display())
    }
}

impl std::str::FromStr for DeviceMountFinalization {
    type Err = String;

    fn from_str(value: &str) -> Result<Self, Self::Err> {
        let (descriptor, destination) = value
            .split_once(':')
            .ok_or("device finalization requires FD:absolute-path")?;
        let descriptor = descriptor
            .parse::<i32>()
            .map_err(|_| "invalid device descriptor")?;
        let destination = std::path::PathBuf::from(destination);
        if descriptor < 3 || !destination.is_absolute() || value.contains('\0') {
            return Err(
                "device finalization requires an owned descriptor and absolute path".into(),
            );
        }
        Ok(Self {
            descriptor,
            destination,
        })
    }
}

/// The hook that carries the ruleset descriptor across that `exec`, without
/// which the helper enters no ruleset while the layer above still reports the
/// filesystem boundary as enforced.
///
/// Re-exported straight from the backend that owns it. The sandbox module's
/// own export list is a length-ratcheted legacy file, and widening it by one
/// name costs two lines there for no benefit to a reader.
#[cfg(target_os = "linux")]
pub use crate::stdlib::sandbox::linux::keep_ruleset_across_exec;
#[cfg(target_os = "linux")]
pub(crate) use crate::stdlib::sandbox::linux::sealed_launch_bytes;
#[cfg(target_os = "linux")]
pub use crate::stdlib::sandbox::linux::DescriptorTransfer;
#[cfg(target_os = "linux")]
pub use crate::stdlib::sandbox::linux::{command_for_reexec, ReexecConfinement};
/// Confinement an embedder builds here and enters in a process it re-execs.
///
/// An embedder that spawns the payload directly never needs this: `pre_exec`
/// carries the Linux confinement for it. One that hands the payload to a helper
/// process does, because a callback cannot cross an `exec` and its loss is
/// silent — the payload runs unconfined and every step before it still reports
/// success.
#[cfg(target_os = "linux")]
pub use crate::stdlib::sandbox::{
    decode_seccomp_hex, transferable_confinement, TransferableConfinement,
};

/// Push a transient execution policy with `sandbox_profile` replaced by the
/// requested profile. The returned guard restores the surrounding policy on
/// drop.
///
/// This is the single per-process override seam used by both the typed
/// `HarnessProcess` capability and hostlib command tools. It deliberately
/// changes only the profile: workspace roots, capability ceilings, and every
/// other policy field continue to come from the surrounding execution.
pub fn push_sandbox_profile_override(
    value: &str,
) -> Result<SandboxProfileOverrideGuard, crate::VmError> {
    let profile = crate::orchestration::SandboxProfile::parse(value).ok_or_else(|| {
        let expected = crate::orchestration::SandboxProfile::all()
            .iter()
            .map(|profile| format!("{:?}", profile.as_str()))
            .collect::<Vec<_>>()
            .join(", ");
        crate::VmError::Thrown(crate::VmValue::String(arcstr::ArcStr::from(format!(
            "unknown sandbox_profile {value:?}; expected one of {expected}"
        ))))
    })?;
    let mut policy = crate::orchestration::current_execution_policy().unwrap_or_default();
    policy.sandbox_profile = profile;
    crate::orchestration::push_execution_policy(policy);
    Ok(SandboxProfileOverrideGuard {
        _private: std::marker::PhantomData,
    })
}

/// Restores the execution policy active before
/// [`push_sandbox_profile_override`] when dropped.
#[must_use = "dropping the guard immediately restores the surrounding sandbox profile"]
#[derive(Debug)]
pub struct SandboxProfileOverrideGuard {
    _private: std::marker::PhantomData<*const ()>,
}

impl Drop for SandboxProfileOverrideGuard {
    fn drop(&mut self) {
        crate::orchestration::pop_execution_policy();
    }
}

/// Recognize an OS-sandbox wrapper that started but could not exec the
/// requested program. Inline-confinement backends return `None`; macOS uses
/// this after `sandbox-exec` exits so callers do not mistake its status for the
/// requested program's exit status.
pub fn wrapped_spawn_io_error(exit_code: i32, stderr: &[u8]) -> Option<std::io::Error> {
    crate::stdlib::sandbox::active_sandbox_policy()?;
    if !active_backend_available() {
        return None;
    }
    #[cfg(target_os = "macos")]
    return macos_wrapped_spawn_io_error(exit_code, stderr);
    #[cfg(not(target_os = "macos"))]
    {
        let _ = (exit_code, stderr);
        None
    }
}

#[cfg(target_os = "macos")]
pub(crate) fn macos_wrapped_spawn_io_error(
    exit_code: i32,
    stderr: &[u8],
) -> Option<std::io::Error> {
    const EX_OSERR: i32 = 71;
    const PREFIX: &str = "sandbox-exec: execvp() of '";
    const SUFFIX: &str = "' failed: No such file or directory\n";

    let stderr = std::str::from_utf8(stderr).ok()?;
    if exit_code == EX_OSERR && stderr.starts_with(PREFIX) && stderr.ends_with(SUFFIX) {
        return Some(std::io::Error::from_raw_os_error(libc::ENOENT));
    }
    None
}

#[cfg(all(test, target_os = "macos"))]
mod tests {
    use super::macos_wrapped_spawn_io_error;

    #[test]
    fn wrapper_missing_program_is_typed_not_found() {
        let error = macos_wrapped_spawn_io_error(
            71,
            b"sandbox-exec: execvp() of 'missing-command' failed: No such file or directory\n",
        )
        .expect("sandbox wrapper failure");
        assert_eq!(error.kind(), std::io::ErrorKind::NotFound);
    }

    #[test]
    fn genuine_exit_71_is_not_a_wrapper_failure() {
        assert!(macos_wrapped_spawn_io_error(71, b"").is_none());
        assert!(macos_wrapped_spawn_io_error(71, b"application failed\n").is_none());
    }
}

#[cfg(test)]
mod profile_override_tests {
    use crate::orchestration::{
        current_execution_policy, pop_execution_policy, push_execution_policy, CapabilityPolicy,
        SandboxProfile,
    };

    use super::push_sandbox_profile_override;

    #[test]
    fn per_call_override_changes_only_the_profile_and_restores_the_parent() {
        let parent = CapabilityPolicy {
            sandbox_profile: SandboxProfile::OsHardened,
            workspace_roots: vec!["/workspace".to_string()],
            tools: vec!["run_command".to_string()],
            ..CapabilityPolicy::default()
        };
        push_execution_policy(parent.clone());

        {
            let _guard = push_sandbox_profile_override("workspace_paths")
                .expect("workspace_paths is a supported profile");
            let current = current_execution_policy().expect("override policy");
            assert_eq!(current.sandbox_profile, SandboxProfile::WorkspacePaths);
            assert_eq!(current.workspace_roots, parent.workspace_roots);
            assert_eq!(current.tools, parent.tools);
        }

        assert_eq!(current_execution_policy().expect("restored parent"), parent);
        pop_execution_policy();
    }

    #[test]
    fn per_call_override_rejects_unknown_profiles_without_mutating_policy() {
        let parent = CapabilityPolicy {
            sandbox_profile: SandboxProfile::Worktree,
            ..CapabilityPolicy::default()
        };
        push_execution_policy(parent.clone());

        let error = push_sandbox_profile_override("wide_open")
            .expect_err("unknown profiles must fail closed");
        assert!(error.to_string().contains("unknown sandbox_profile"));
        assert_eq!(
            current_execution_policy().expect("unchanged parent"),
            parent
        );
        pop_execution_policy();
    }
}