From 1165aea9aa1157e229265c0f0109bc141f07a002 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Krist=C3=B3f=20T=C3=B3th?= <mrtoth@strongds.hu>
Date: Mon, 27 Apr 2026 21:08:05 +0200
Subject: [PATCH] Stop overriding the sandbox hostname

Setting --hostname sandbox inside the UTS namespace was purely cosmetic
(a label for interactive shells) and provided no isolation beyond what
--unshare-uts already gives. It also caused codex to hang for ~5s on
startup: glibc resolved the unknown "sandbox" name via systemd-resolved
and waited through two DNS retry timeouts before giving up.

Dropping the override lets the sandbox inherit the host's hostname,
which already resolves locally, eliminating the stall.
---
 README.md      | 2 +-
 src/cli.rs     | 2 +-
 src/sandbox.rs | 1 -
 3 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index 032f57b..a62654f 100644
--- a/README.md
+++ b/README.md
@@ -18,7 +18,7 @@ The threat model is prompt injection and accidental damage, not a determined att
 
 ### Hardening
 
-`--hardened` unshares the IPC, PID, and UTS namespaces and sets the hostname to `sandbox`. This is independent of the filesystem mode and can be combined with either. Whitelist mode enables it unconditionally; blacklist mode leaves it off by default. Use `--no-hardened` to override a config-file `hardened = true` (note: it cannot disable the implicit hardening that comes with whitelist mode).
+`--hardened` unshares the IPC, PID, and UTS namespaces. This is independent of the filesystem mode and can be combined with either. Whitelist mode enables it unconditionally; blacklist mode leaves it off by default. Use `--no-hardened` to override a config-file `hardened = true` (note: it cannot disable the implicit hardening that comes with whitelist mode).
 
 ### Network
 
diff --git a/src/cli.rs b/src/cli.rs
index 39bbdcf..bdb49c9 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -18,7 +18,7 @@ pub struct Args {
     #[arg(long)]
     pub whitelist: bool,
 
-    /// Harden: unshare IPC, PID, UTS namespaces and set hostname to "sandbox" (implied by --whitelist)
+    /// Harden: unshare IPC, PID, UTS namespaces (implied by --whitelist)
     #[arg(long, overrides_with = "no_hardened")]
     pub hardened: bool,
 
diff --git a/src/sandbox.rs b/src/sandbox.rs
index 62f1a49..63af62f 100644
--- a/src/sandbox.rs
+++ b/src/sandbox.rs
@@ -13,7 +13,6 @@ pub fn build_command(config: &SandboxConfig) -> Result<Command, SandboxError> {
 
     if hardened {
         cmd.args(["--unshare-ipc", "--unshare-pid", "--unshare-uts"]);
-        cmd.args(["--hostname", "sandbox"]);
     }
     if config.unshare_net {
         cmd.arg("--unshare-net");