fix(702): narrow all PrivRequest handlers to specific ops

hive-priv/src/main.rs

@@ -9,13 +9,14 @@
 //! **Security model**: every request is validated against a strict
 //! container-name allowlist before any filesystem or process operation.
 //! Only containers whose names match the hive convention (`h-*`,
-//! the manager container, or known sibling services) are accepted.
+//! the manager container, or known sibling service containers) are
+//! accepted. Every variant maps to a single known operation — no
+//! arbitrary command pass-through.
 //!
 //! **Socket activation**: when systemd passes the listener socket via
 //! `LISTEN_FDS=1` + `LISTEN_PID=<self>`, the inherited fd 3 is used
 //! instead of binding a fresh socket.
 
-use std::os::unix::fs::PermissionsExt as _;
 use std::path::{Path, PathBuf};
 
 use anyhow::{Context as _, Result, bail};
@@ -28,13 +29,13 @@ use tokio::process::Command;
 const AGENT_PREFIX: &str = "h-";
 
 /// Manager container name (mirrors `lifecycle::MANAGER_NAME`).
-const MANAGER_NAME: &str = "hm1nd";
+const MANAGER_NAME: &str = "root";
 
 /// Sibling service containers managed by hive-c0re.
 const SIBLING_CONTAINERS: &[&str] = &["hive-forge", "hive-matrix", "hive-gateway"];
 
-/// Allowed path prefixes for `Chown` / `Chmod` operations.
-const SAFE_PATH_PREFIXES: &[&str] = &["/run/hive-agent/", "/var/lib/hyperhive/"];
+/// Root of the per-agent unix-socket dirs on the host.
+const SOCKET_DIR_ROOT: &str = "/run/hive-agent";
 
 #[tokio::main]
 async fn main() -> Result<()> {
@@ -94,9 +95,9 @@ fn socket_listener() -> Result<UnixListener> {
             .with_context(|| format!("create {}", parent.display()))?;
     }
     let _ = std::fs::remove_file(path);
-    let listener =
-        UnixListener::bind(path).with_context(|| format!("bind {PRIV_SOCK}"))?;
+    let listener = UnixListener::bind(path).with_context(|| format!("bind {PRIV_SOCK}"))?;
     // Mode 0660: only the hive-core group can connect.
+    use std::os::unix::fs::PermissionsExt as _;
     std::fs::set_permissions(path, std::fs::Permissions::from_mode(0o660))
         .context("chmod priv.sock")?;
     tracing::info!(path = PRIV_SOCK, "bound priv socket");
@@ -147,32 +148,69 @@ async fn dispatch(line: &str) -> PrivResponse {
 /// Execute a validated `PrivRequest`. Returns `(stdout, stderr)` on success.
 async fn exec(req: PrivRequest) -> Result<(String, String)> {
     match req {
-        PrivRequest::ContainerRun { ref args } => {
-            validate_container_args(args)?;
-            let out = Command::new("nixos-container")
-                .args(args)
-                .output()
-                .await
-                .context("invoke nixos-container")?;
-            let stdout = String::from_utf8_lossy(&out.stdout).into_owned();
-            let stderr = String::from_utf8_lossy(&out.stderr).into_owned();
-            // Log each line so progress is visible in journald even
-            // without a streaming protocol.
-            for line in stdout.lines() {
-                tracing::info!(target: "nixos-container", "{line}");
+        PrivRequest::StartContainer { ref name } => {
+            validate_container_name(name)?;
+            container_run(&["start", &container_system_name(name)]).await
+        }
+
+        PrivRequest::StopContainer { ref name } => {
+            validate_container_name(name)?;
+            container_run(&["stop", &container_system_name(name)]).await
+        }
+
+        PrivRequest::KillContainer { ref name } => {
+            validate_container_name(name)?;
+            container_run(&["kill", &container_system_name(name)]).await
+        }
+
+        PrivRequest::UpdateContainer { ref name, ref flake_ref } => {
+            validate_container_name(name)?;
+            validate_flake_ref(flake_ref)?;
+            container_run(&["update", &container_system_name(name), "--flake", flake_ref]).await
+        }
+
+        PrivRequest::CreateContainer { ref name, ref flake_ref } => {
+            validate_container_name(name)?;
+            validate_flake_ref(flake_ref)?;
+            container_run(&["create", &container_system_name(name), "--flake", flake_ref]).await
+        }
+
+        PrivRequest::DestroyContainer { ref name } => {
+            validate_container_name(name)?;
+            container_run(&["destroy", &container_system_name(name)]).await
+        }
+
+        PrivRequest::ListContainers => container_run(&["list"]).await,
+
+        PrivRequest::WriteNspawnConf { ref container, ref content } => {
+            validate_container_system_name(container)?;
+            let path = format!("/etc/nixos-containers/{container}.conf");
+            std::fs::write(&path, content).with_context(|| format!("write {path}"))?;
+            Ok((String::new(), String::new()))
+        }
+
+        PrivRequest::WriteResourceLimits {
+            ref container,
+            ref memory_max,
+            ref cpu_quota,
+        } => {
+            validate_container_system_name(container)?;
+            let dir = format!("/run/systemd/system/container@{container}.service.d");
+            std::fs::create_dir_all(&dir).with_context(|| format!("create {dir}"))?;
+            let path = format!("{dir}/hyperhive-limits.conf");
+            let content = format!("[Service]\nMemoryMax={memory_max}\nCPUQuota={cpu_quota}\n");
+            std::fs::write(&path, content).with_context(|| format!("write {path}"))?;
+            Ok((String::new(), String::new()))
+        }
+
+        PrivRequest::RemoveServiceDropin { ref container } => {
+            validate_container_system_name(container)?;
+            let dir = format!("/run/systemd/system/container@{container}.service.d");
+            if Path::new(&dir).exists() {
+                std::fs::remove_dir_all(&dir)
+                    .with_context(|| format!("remove {dir}"))?;
             }
-            for line in stderr.lines() {
-                tracing::warn!(target: "nixos-container", "{line}");
-            }
-            if !out.status.success() {
-                bail!(
-                    "nixos-container {} failed ({}): {}",
-                    args.join(" "),
-                    out.status,
-                    stderr.trim()
-                );
-            }
-            Ok((stdout, stderr))
+            Ok((String::new(), String::new()))
         }
 
         PrivRequest::DaemonReload => {
@@ -191,58 +229,6 @@ async fn exec(req: PrivRequest) -> Result<(String, String)> {
             Ok((String::new(), String::new()))
         }
 
-        PrivRequest::WriteNspawnConf { ref container, ref content } => {
-            validate_container_name(container)?;
-            let path = format!("/etc/nixos-containers/{container}.conf");
-            std::fs::write(&path, content).with_context(|| format!("write {path}"))?;
-            Ok((String::new(), String::new()))
-        }
-
-        PrivRequest::WriteSystemdDropin {
-            ref container,
-            ref filename,
-            ref content,
-        } => {
-            validate_container_name(container)?;
-            validate_dropin_filename(filename)?;
-            let dir =
-                format!("/run/systemd/system/container@{container}.service.d");
-            std::fs::create_dir_all(&dir)
-                .with_context(|| format!("create {dir}"))?;
-            let path = format!("{dir}/{filename}");
-            std::fs::write(&path, content).with_context(|| format!("write {path}"))?;
-            Ok((String::new(), String::new()))
-        }
-
-        PrivRequest::RemoveSystemdDropin { ref container } => {
-            validate_container_name(container)?;
-            let dir =
-                format!("/run/systemd/system/container@{container}.service.d");
-            if Path::new(&dir).exists() {
-                std::fs::remove_dir_all(&dir)
-                    .with_context(|| format!("remove {dir}"))?;
-            }
-            Ok((String::new(), String::new()))
-        }
-
-        PrivRequest::Chown { ref path, uid, gid } => {
-            validate_safe_path(path)?;
-            std::os::unix::fs::chown(path, Some(uid), Some(gid))
-                .with_context(|| {
-                    format!("chown {} to {uid}:{gid}", path.display())
-                })?;
-            Ok((String::new(), String::new()))
-        }
-
-        PrivRequest::Chmod { ref path, mode } => {
-            validate_safe_path(path)?;
-            std::fs::set_permissions(path, std::fs::Permissions::from_mode(mode))
-                .with_context(|| {
-                    format!("chmod {:o} {}", mode, path.display())
-                })?;
-            Ok((String::new(), String::new()))
-        }
-
         PrivRequest::ReloadGatewayNginx => {
             let out = Command::new("systemd-run")
                 .args(["--machine=hive-gateway", "--quiet", "--", "nginx", "-s", "reload"])
@@ -258,27 +244,78 @@ async fn exec(req: PrivRequest) -> Result<(String, String)> {
             }
             Ok((String::new(), String::new()))
         }
+
+        PrivRequest::ChownSocketDir { ref agent_name, uid, gid } => {
+            validate_agent_name(agent_name)?;
+            let path = socket_dir_path(agent_name);
+            std::os::unix::fs::chown(&path, Some(uid), Some(gid))
+                .with_context(|| format!("chown {} to {uid}:{gid}", path.display()))?;
+            Ok((String::new(), String::new()))
+        }
+
+        PrivRequest::ChmodSocketDir { ref agent_name, mode } => {
+            validate_agent_name(agent_name)?;
+            let path = socket_dir_path(agent_name);
+            use std::os::unix::fs::PermissionsExt as _;
+            std::fs::set_permissions(&path, std::fs::Permissions::from_mode(mode))
+                .with_context(|| format!("chmod {:o} {}", mode, path.display()))?;
+            Ok((String::new(), String::new()))
+        }
     }
 }
 
-/// Validate that nixos-container args reference only hive-managed containers.
-fn validate_container_args(args: &[String]) -> Result<()> {
-    if args.is_empty() {
-        bail!("ContainerRun: args must not be empty");
+/// Invoke `nixos-container` with the given args, log output to journald.
+async fn container_run(args: &[&str]) -> Result<(String, String)> {
+    let out = Command::new("nixos-container")
+        .args(args)
+        .output()
+        .await
+        .context("invoke nixos-container")?;
+    let stdout = String::from_utf8_lossy(&out.stdout).into_owned();
+    let stderr = String::from_utf8_lossy(&out.stderr).into_owned();
+    for line in stdout.lines() {
+        tracing::info!(target: "nixos-container", "{line}");
     }
-    // Verbs whose second positional argument is a container name.
-    const CONTAINER_ARG_VERBS: &[&str] =
-        &["start", "stop", "kill", "restart", "destroy", "update", "run", "create"];
-    if CONTAINER_ARG_VERBS.contains(&args[0].as_str()) {
-        if let Some(name) = args.get(1) {
-            validate_container_name(name)?;
-        }
+    for line in stderr.lines() {
+        tracing::warn!(target: "nixos-container", "{line}");
     }
-    // `list` and unknown verbs take no container arg - no further validation needed.
+    if !out.status.success() {
+        bail!(
+            "nixos-container {} failed ({}): {}",
+            args.join(" "),
+            out.status,
+            stderr.trim()
+        );
+    }
+    Ok((stdout, stderr))
+}
+
+/// Return the system container name for a logical agent name.
+/// Manager (`MANAGER_NAME`) passes through; sub-agents get `h-` prefix.
+fn container_system_name(name: &str) -> String {
+    if name == MANAGER_NAME {
+        name.to_owned()
+    } else {
+        format!("{AGENT_PREFIX}{name}")
+    }
+}
+
+/// Path of the per-agent unix-socket dir on the host.
+fn socket_dir_path(agent_name: &str) -> PathBuf {
+    PathBuf::from(format!("{SOCKET_DIR_ROOT}/{agent_name}"))
+}
+
+/// Validate a logical agent name (the name hive-c0re uses internally,
+/// before the `h-` container prefix is applied).
+fn validate_agent_name(name: &str) -> Result<()> {
+    if name == MANAGER_NAME {
+        return Ok(());
+    }
+    validate_name_chars(name)?;
     Ok(())
 }
 
-/// Validate that a container name is managed by hive.
+/// Validate a logical agent name and check it maps to a hive-managed container.
 fn validate_container_name(name: &str) -> Result<()> {
     if name == MANAGER_NAME {
         return Ok(());
@@ -286,30 +323,40 @@ fn validate_container_name(name: &str) -> Result<()> {
     if SIBLING_CONTAINERS.contains(&name) {
         return Ok(());
     }
-    if name.starts_with(AGENT_PREFIX) {
-        let suffix = &name[AGENT_PREFIX.len()..];
-        if !suffix.is_empty()
-            && suffix.chars().all(|c| c.is_ascii_lowercase() || c.is_ascii_digit() || c == '-')
-        {
-            return Ok(());
-        }
+    validate_name_chars(name)?;
+    Ok(())
+}
+
+/// Validate a system-level container name (already has `h-` prefix for
+/// sub-agents, or is the manager name / sibling service name).
+fn validate_container_system_name(name: &str) -> Result<()> {
+    if name == MANAGER_NAME {
+        return Ok(());
+    }
+    if SIBLING_CONTAINERS.contains(&name) {
+        return Ok(());
+    }
+    if let Some(suffix) = name.strip_prefix(AGENT_PREFIX) {
+        validate_name_chars(suffix)?;
+        return Ok(());
     }
     bail!("container name {name:?} is not managed by hive");
 }
 
-fn validate_dropin_filename(filename: &str) -> Result<()> {
-    if filename.is_empty() || filename.contains('/') || filename.contains("..") {
-        bail!("invalid drop-in filename: {filename:?}");
+fn validate_name_chars(name: &str) -> Result<()> {
+    if name.is_empty()
+        || !name
+            .chars()
+            .all(|c| c.is_ascii_lowercase() || c.is_ascii_digit() || c == '-')
+    {
+        bail!("invalid name {name:?}: must be non-empty lowercase ascii + digits + hyphens");
     }
     Ok(())
 }
 
-fn validate_safe_path(path: &Path) -> Result<()> {
-    let s = path.to_string_lossy();
-    for prefix in SAFE_PATH_PREFIXES {
-        if s.starts_with(prefix) && !s.contains("..") {
-            return Ok(());
-        }
+fn validate_flake_ref(flake_ref: &str) -> Result<()> {
+    if flake_ref.is_empty() || flake_ref.contains('\n') || flake_ref.contains('\0') {
+        bail!("invalid flake_ref {flake_ref:?}");
     }
-    bail!("path {} is outside allowed prefixes", path.display());
+    Ok(())
 }