From a14a73b54af26af4a5428ba2eb482a1ce54f8974 Mon Sep 17 00:00:00 2001 From: viyatb-oai Date: Fri, 5 Jun 2026 08:00:46 -0700 Subject: [PATCH] [codex] Fix long proxy socket paths (#26553) ## Summary - avoid generating host proxy bridge Unix socket paths that exceed Linux's `sockaddr_un.sun_path` limit - fall back from a long `$CODEX_HOME/tmp` path to the system temp directory, then `/tmp` - add focused unit coverage for short and overlong parent paths ## Root cause With a sufficiently long `CODEX_HOME`, the generated `proxy-route-*.sock` path exceeds Linux's 107-byte pathname limit. The host bridge child exits before writing its readiness byte, so the parent reports the indirect error `failed to prepare host proxy routing bridge: failed to fill whole buffer`. ## Validation - reproduced the original error with a long `CODEX_HOME` using `codex-cli 0.138.0-alpha.4` - `cargo clippy -p codex-linux-sandbox --all-targets` - `just fix -p codex-linux-sandbox` - `just fmt` The Linux-only unit test could not execute locally: the arm64 Docker build was repeatedly OOM-killed by `rustc` while compiling an unrelated `codex-app-server-protocol` dependency, before reaching the test. --------- Co-authored-by: Codex --- codex-rs/linux-sandbox/src/proxy_routing.rs | 45 +++++++++++++++++++-- 1 file changed, 42 insertions(+), 3 deletions(-) diff --git a/codex-rs/linux-sandbox/src/proxy_routing.rs b/codex-rs/linux-sandbox/src/proxy_routing.rs index d28b86466..f171d9174 100644 --- a/codex-rs/linux-sandbox/src/proxy_routing.rs +++ b/codex-rs/linux-sandbox/src/proxy_routing.rs @@ -14,6 +14,7 @@ use std::net::SocketAddr; use std::net::TcpListener; use std::net::TcpStream; use std::os::fd::FromRawFd; +use std::os::unix::ffi::OsStrExt; use std::os::unix::fs::DirBuilderExt; use std::os::unix::fs::PermissionsExt; use std::os::unix::net::UnixListener; @@ -43,6 +44,8 @@ const PROXY_ENV_KEYS: &[&str] = &[ const PROXY_SOCKET_DIR_PREFIX: &str = "codex-linux-sandbox-proxy-"; const HOST_BRIDGE_READY: u8 = 1; const LOOPBACK_INTERFACE_NAME: &[u8] = b"lo"; +// Linux sockaddr_un.sun_path allows 108 bytes, including the trailing NUL. +const UNIX_SOCKET_PATH_MAX_BYTES: usize = 107; #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)] pub(crate) struct ProxyRouteSpec { @@ -278,8 +281,9 @@ fn rewrite_proxy_env_value(proxy_url: &str, local_port: u16) -> Option { fn create_proxy_socket_dir() -> io::Result { let temp_dir = proxy_socket_parent_dir(); let pid = std::process::id(); + let uid = unsafe { libc::geteuid() }; for attempt in 0..128 { - let candidate = temp_dir.join(format!("{PROXY_SOCKET_DIR_PREFIX}{pid}-{attempt}")); + let candidate = temp_dir.join(format!("{PROXY_SOCKET_DIR_PREFIX}{pid}-{uid}-{attempt}")); // The bridge UDS paths live under a shared temp root, so the per-run // directory should not be traversable by other processes. let mut dir_builder = DirBuilder::new(); @@ -302,11 +306,29 @@ fn create_proxy_socket_dir() -> io::Result { fn proxy_socket_parent_dir() -> PathBuf { if let Some(codex_home) = std::env::var_os("CODEX_HOME") { let candidate = PathBuf::from(codex_home).join("tmp"); - if ensure_private_proxy_socket_parent_dir(candidate.as_path()).is_ok() { + if proxy_socket_paths_fit(candidate.as_path()) + && ensure_private_proxy_socket_parent_dir(candidate.as_path()).is_ok() + { return candidate; } } - std::env::temp_dir() + let temp_dir = std::env::temp_dir(); + if proxy_socket_paths_fit(temp_dir.as_path()) { + temp_dir + } else { + PathBuf::from("/tmp") + } +} + +fn proxy_socket_paths_fit(parent: &Path) -> bool { + let socket_path = parent + .join(format!( + "{PROXY_SOCKET_DIR_PREFIX}{}-{}-127", + u32::MAX, + libc::uid_t::MAX + )) + .join(format!("proxy-route-{}.sock", usize::MAX)); + socket_path.as_os_str().as_bytes().len() <= UNIX_SOCKET_PATH_MAX_BYTES } fn ensure_private_proxy_socket_parent_dir(path: &Path) -> io::Result<()> { @@ -661,6 +683,7 @@ mod tests { use super::parse_loopback_proxy_endpoint; use super::parse_proxy_socket_dir_owner_pid; use super::plan_proxy_routes; + use super::proxy_socket_paths_fit; use super::rewrite_proxy_env_value; use pretty_assertions::assert_eq; use std::collections::HashMap; @@ -735,6 +758,18 @@ mod tests { assert_eq!(default_proxy_port("socks5h"), 1080); } + #[test] + fn proxy_socket_paths_enforce_linux_path_limit() { + assert_eq!( + proxy_socket_paths_fit(PathBuf::from("/tmp").as_path()), + true + ); + assert_eq!( + proxy_socket_paths_fit(PathBuf::from(format!("/tmp/{}", "a".repeat(96))).as_path()), + false + ); + } + #[test] fn cleanup_proxy_socket_dir_removes_bridge_artifacts() { let root = tempfile::tempdir().expect("tempdir should create"); @@ -770,6 +805,10 @@ mod tests { parse_proxy_socket_dir_owner_pid("codex-linux-sandbox-proxy-1234-0"), Some(1234) ); + assert_eq!( + parse_proxy_socket_dir_owner_pid("codex-linux-sandbox-proxy-1234-1000-0"), + Some(1234) + ); assert_eq!( parse_proxy_socket_dir_owner_pid("codex-linux-sandbox-proxy-x"), None