The agent SSH server unconditionally allows all four SSH forwarding
paths (TCP local, TCP reverse, Unix local, Unix reverse). This is a
sandbox escape vector when workspaces are used for AI agent containment
— a reverse tunnel lets anything inside the workspace reach the user's
local machine, bypassing network isolation.
This adds two new agent CLI flags / environment variables:
- `--block-reverse-port-forwarding` /
`CODER_AGENT_BLOCK_REVERSE_PORT_FORWARDING` — blocks both TCP (`ssh -R`)
and Unix socket reverse forwarding
- `--block-local-port-forwarding` /
`CODER_AGENT_BLOCK_LOCAL_PORT_FORWARDING` — blocks both TCP (`ssh -L`)
and Unix socket local forwarding
Template admins can set these via the `env` block on the container/VM
resource that runs the agent (e.g. `docker_container`,
`kubernetes_pod`), or via `coder_env` resources tied to the agent.
Fixes https://github.com/coder/coder/issues/22275
<details>
<summary>Implementation notes</summary>
Follows the existing `BlockFileTransfer` pattern:
1. `agent/agentssh/agentssh.go` — New `BlockReversePortForwarding` and
`BlockLocalPortForwarding` fields on `Config`. TCP callbacks check these
before allowing forwarding. The `direct-streamlocal@openssh.com` channel
handler is wrapped to reject Unix local forwards.
2. `agent/agentssh/forward.go` — `forwardedUnixHandler` gains a
`blockReversePortForwarding` field to reject
`streamlocal-forward@openssh.com` requests.
3. `agent/agent.go` — New fields on `Options` and `agent` struct,
plumbed to SSH config.
4. `cli/agent.go` — New serpent flags with env vars.
5. Tests cover all four blocked paths: TCP local, TCP reverse, Unix
local, Unix reverse.
</details>
> 🤖 Generated by Coder Agents
Upgrades to slog v3 which includes a small, but backward incompatible API change to the acceptible call arguments when logging. This change allows us to verify via compile time type checking that arguments are correct and won't cause a panic, as was possible in slog v1, which this replaces (v2 was tagged but never used in coder/coder).
It also updates dependencies that also use slog and were updated.
I've left the `aibridge` dependency as a commit SHA, under the assumption that the team there (cc @pawbana @dannykopping ) will tag and update the dependency soon and on their own schedule.
Other dependencies, I pushed new tags.
Fixes an issue where remote forwards are not correctly torn down when using OpenSSH with `coder ssh --stdio`. OpenSSH sends a disconnect signal, but then also sends SIGHUP to `coder`. Previously, we just exited when we got SIGHUP, and this raced against properly disconnecting.
Fixes https://github.com/coder/customers/issues/327
Garrett Delfosse