Richard FeldmanandMartinYe1234
4e04617329
Third of the `http_proxy` stack. Stacked on #59217 and the upstream-config PR — review/merge those first. Adds the in-process HTTP/HTTPS proxy server that enforces an `Allowlist`. It speaks HTTP CONNECT for HTTPS tunnels and forward proxying for plain HTTP, vets resolved addresses against loopback/private/link-local ranges to prevent DNS-rebinding past the sandbox, pins each connection to the destination approved for its first request (so later keep-alive requests can't escape the policy decision), optionally chains through the upstream proxy, and bounds header sizes, connection counts, and connect/handshake waits since its sole client is untrusted model-driven code running inside the editor process. Includes end-to-end tests covering allowed/denied CONNECT and HTTP forward, IP-literal handling, DNS-rebinding denial, and upstream chaining. Still has no callers; wired into the agent terminal sandbox in the remaining PRs of the stack. Release Notes: - N/A --------- Co-authored-by: MartinYe1234 <52641447+MartinYe1234@users.noreply.github.com>
56 lines
2.9 KiB
Rust
56 lines
2.9 KiB
Rust
//! In-process HTTP/HTTPS proxy that enforces a hostname allowlist.
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//!
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//! Spawned per terminal command from the parent process. The sandbox is
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//! configured to permit network only to this proxy's port; everything the
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//! sandboxed command tries to reach the network for has to come through here.
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//!
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//! The proxy:
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//!
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//! - Speaks HTTP CONNECT for HTTPS tunnels and HTTP forward proxying for
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//! plain HTTP. Other protocols cannot reach it (the seatbelt rule limits
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//! the sandboxed process to this one TCP destination, and this proxy only
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//! speaks HTTP).
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//! - Checks the destination hostname against an allowlist of exact hostnames
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//! and leading-`*.` subdomain wildcards. Unless the allowlist allows any
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//! host, IP-literal targets are denied, and hostnames whose DNS resolves
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//! only into loopback / private / link-local space are denied too
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//! (DNS-rebinding protection — the proxy runs outside the sandbox, so it
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//! must not reopen the local network the Seatbelt rule closed off).
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//! - Pins each TCP connection to the destination approved for its first
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//! request: directly (to the vetted resolved addresses) or via a CONNECT
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//! tunnel through an optional upstream HTTP proxy from the parent's
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//! environment (`HTTPS_PROXY` / `HTTP_PROXY`), honoring `NO_PROXY`. Plain
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//! HTTP is also tunneled when chaining, so keep-alive requests after the
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//! first can never be routed to a different host by the upstream.
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//! - Reports per-connection events (allowed, denied, completed) over an
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//! mpsc supplied by the caller.
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//!
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//! ## Trust assumptions
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//!
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//! The proxy's sole client is model-driven code running inside the sandbox —
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//! exactly the party the sandbox distrusts — and the proxy itself runs inside
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//! the editor process. It therefore caps request header sizes and concurrent
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//! connections, and bounds connect/handshake waits with timeouts, so a
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//! malicious command can't exhaust the editor's memory, threads, or file
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//! descriptors through it. Bandwidth is deliberately not capped; the
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//! command's lifetime bounds it.
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//!
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//! ## "No proxy here" principle
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//!
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//! The agent and tools running inside the sandbox should not need to know
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//! that a proxy is in front of them. The only response code the proxy
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//! synthesizes itself is `511 Network Authentication Required`, used solely
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//! for policy denials (with `Via:` and `Proxy-Status:` headers and a
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//! plain-text body explaining the policy decision). Other failure modes
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//! (upstream connection failure, malformed input from the client, etc.) are
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//! handled by silently closing the connection — same behavior the client
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//! would see from a direct network failure, no proxy fingerprint.
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mod allowlist;
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mod proxy;
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pub use allowlist::{Allowlist, HostPattern, HostPatternError};
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pub use proxy::{
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DenyReason, ProxyConfig, ProxyEvent, ProxyHandle, RequestMethod, RequestOutcome, UpstreamProxy,
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};
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