feat(spike-E): resolve Cap'n Proto socketpair stall; wire RPC transport (M2 prereq)
The M0 Spike E recorded that Cap'n Proto two-party RPC over an AF_UNIX socketpair stalled (server processed requests, responses never reached the client). Root cause, confirmed with a standalone reproduction: EzRpcServer(int fd, ...) expects a LISTENING socket and calls accept() on it; a socketpair end is already CONNECTED, so accept() fails with EINVAL and the bootstrap never completes. Fix: server side uses the low-level path — LowLevelAsyncIoProvider::wrapSocketFd(fd) + TwoPartyVatNetwork(SIDE_SERVER) + makeRpcServer(network, bootstrap). The client uses EzRpcClient(fd), which is designed for an already-connected socket. This is the production M2 transport shape. - spike/E_sandbox/DocumentProcess.cpp: low-level TwoPartyVatNetwork server over wrapSocketFd; serves DocumentProcess::Server capability with 16 MiB payload cap (ADR-0004 bidirectional trust boundary) - spike/E_sandbox/UIProcess.cpp: EzRpcClient(fd) + parse() RPC; validates every response field. ASan caught a use-after-free (ParseResult::Reader outliving its Response) — fixed by validating inside the Response scope (validates §7.2 sanitizers-from-day-one) - spike/E_sandbox/Sandbox.cpp: allow ioctl (FIONBIO) — KJ's wrapSocketFd sets non-blocking mode via ioctl; strace identified it as the denied syscall - spike/CMakeLists.txt: Cap'n Proto via pkg-config (the Debian CMake config hard-requires libatomic via a check that fails on x86-64 where it isn't needed); schema compiled with the capnp tool + --src-prefix - docs/spike-results/0004: record the resolution; gate still MET (1000/1000 under seccomp, ~58us avg; ASan-clean with sandbox disabled — ASan's pipe2 conflicts with the seccomp allow-list, an ASan-only artefact)
This commit is contained in:
ai-ad4
parent
067bb7c362
commit
d43d0402b8
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@ -25,6 +25,12 @@ vcpkg_installed/
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**/*.rs.bk
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Cargo.lock.bak
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# Cap'n Proto generated output (Spike E). The build generates these into the
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# build dir; never commit generated capnp C++ to the source tree.
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/ipc.capnp.c++
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/ipc.capnp.h
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**/E_sandbox_generated/
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# OS junk
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.DS_Store
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Thumbs.db
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@ -5,7 +5,8 @@ SPDX-FileCopyrightText: 2025 ai-ad4 and the FreePDFEditor contributors
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# Spike E — sandbox + IPC bring-up: M0 result
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* **Spike**: E — sandbox + IPC bring-up (engineering plan §14 step 8)
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* **Date**: 2025-07-25
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* **Date**: 2025-07-25 (M0); **updated 2026-07-27** — Cap'n Proto socketpair
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stall resolved, RPC transport wired in.
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* **Status**: Complete. **Gate MET.**
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* **Gate**: the sandboxed document process round-trips IPC requests with the
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seccomp filter installed (proving the allow-list is correct and the channel
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@ -19,18 +20,22 @@ SPDX-FileCopyrightText: 2025 ai-ad4 and the FreePDFEditor contributors
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Default-deny (`SCMP_ACT_KILL_PROCESS`), then permit only: memory management
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(mmap/munmap/mprotect/brk/...), thread sync (futex), the already-open IPC
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socket fds (read/write/close/readv/writev/poll/epoll/eventfd/timerfd/dup),
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`ioctl` (FIONBIO, needed by KJ's `wrapSocketFd` to set non-blocking mode),
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and exit/signal. **DENIED**: `socket`, `connect`, `open`/`openat`, `unlink`,
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`fork`, `exec` — the document process cannot reach the network or the
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filesystem, and cannot spawn children. A forbidden syscall kills the process
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loudly rather than silently falling back.
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- `ipc.capnp` — a Cap'n Proto schema for the IPC protocol (kept for the M2
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RPC work; see "Findings" for why the spike uses a raw protocol instead).
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- `ipc.capnp` — a Cap'n Proto schema for the IPC protocol. **Now the actual
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transport** (see "Findings" for the resolution of the original stall).
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- `DocumentProcess.cpp` — the sandboxed child: installs the seccomp filter,
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then serves Parse requests over the socketpair. Trivial length-prefixed
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binary protocol: `[u64 request_id][u64 payload_len][payload]` →
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`[u64 request_id][u64 byte_count][u8 ok]`. Bounds-checks the payload length
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(16 MiB cap) per ADR-0004's "the document process is untrusted" rule.
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- `UIProcess.cpp` — the UI process: sends Parse requests, measures round-trip
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then serves Parse requests over the socketpair via Cap'n Proto two-party
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RPC. Uses the low-level `LowLevelAsyncIoProvider::wrapSocketFd(fd)` +
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`TwoPartyVatNetwork(SIDE_SERVER)` + `makeRpcServer(network, bootstrap)` path
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(NOT `EzRpcServer` — see Findings). The `DocumentProcess::Server` capability
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bounds-checks the payload length (16 MiB cap) per ADR-0004's "the document
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process is untrusted" rule.
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- `UIProcess.cpp` — the UI process: uses `EzRpcClient(fd)` (designed for an
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already-connected socket), calls `parse()` N times, measures round-trip
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latency, and **validates every response** (request id, byte count, ok flag)
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per ADR-0004's "IPC is a trust boundary in both directions" rule.
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- `main.cpp` — forks, sets up the socketpair, runs both sides, measures.
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@ -43,46 +48,74 @@ SPDX-FileCopyrightText: 2025 ai-ad4 and the FreePDFEditor contributors
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| Configuration | avg latency | min | max | child exit |
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|---|---|---|---|---|
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| sandbox ON, Release, 1KB payload, 1000 reqs | **18.0 µs** | 7.0 µs | 330.6 µs | 0 (clean) |
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| sandbox OFF, Release, 1KB payload, 1000 reqs | 20.1 µs | 7.8 µs | 630.9 µs | 0 |
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| sandbox ON, ASan+UBSan, 512B payload, 200 reqs | 33.7 µs | 7.7 µs | 2005.9 µs | 0 |
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| sandbox ON, Release, 1KB payload, 1000 reqs (Cap'n Proto RPC) | **~58 µs** | ~28 µs | ~350 µs | 0 (clean) |
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| sandbox OFF, Release, 1KB payload, 1000 reqs (Cap'n Proto RPC) | ~50 µs | ~28 µs | ~1.5 ms | 0 |
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| sandbox OFF, ASan+UBSan, 512B payload, 200 reqs (Cap'n Proto RPC) | ~480 µs | ~100 µs | ~4.3 ms | 0 |
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The sandbox adds **no measurable latency overhead** (18.0 vs 20.1 µs is within
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noise; seccomp-bpf is a per-syscall filter checked in the kernel, not per-byte).
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Verified clean under ASan+UBSan.
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The sandbox adds no measurable latency overhead. The Cap'n Proto RPC framing
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(~50–58 µs/round-trip) is ~3× the raw length-prefixed protocol it replaced
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(~18 µs) — expected, since RPC adds message framing, the bootstrap
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handshake, and the KJ event loop — and still far inside the §5 budget (the
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document process's open latency budget is < 800 ms for a 1000-page file →
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first page; the per-request IPC cost is negligible against that). Verified
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clean under ASan+UBSan (with the sandbox disabled — see Findings for why ASan
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and seccomp don't combine in this spike).
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## Findings
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1. **The process split works and is cheap.** 18 µs average round-trip per IPC
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request, well under the §5 performance targets (the document process's
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open latency budget is < 800 ms for a 1000-page file → first page; the
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per-request IPC cost is negligible against that). The sandbox is free. The
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§14 step 8 concern ("measure the cost of the process split") is answered:
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the cost is ~tens of microseconds per request, not milliseconds.
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1. **The process split works and is cheap.** ~50 µs average round-trip per
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Cap'n Proto RPC request over the socketpair, well under the §5 performance
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targets. The sandbox is free. The §14 step 8 concern ("measure the cost of
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the process split") is answered: the cost is tens of microseconds per
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request, not milliseconds.
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2. **The seccomp allow-list is correct.** The document process runs its event
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loop (poll/epoll), reads/writes the IPC socket, allocates memory, and exits
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— all under the filter, with no denials. A forbidden syscall
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(`open`/`socket`/`connect`/`fork`/`exec`) would trigger
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`SCMP_ACT_KILL_PROCESS`, crashing the process loudly (a sandbox escape
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attempt is visible, not silent). The Cap'n Proto event loop needed
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`epoll_create1`/`epoll_ctl`/`epoll_wait`/`eventfd2`/`timerfd_*` in the
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allow-list; the raw protocol only needs `read`/`write`.
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2. **The seccomp allow-list is correct for the RPC event loop.** The document
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process runs the KJ event loop (epoll/eventfd/timerfd), reads/writes the
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IPC socket, allocates memory, and exits — all under the filter, with no
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denials. A forbidden syscall (`open`/`socket`/`connect`/`fork`/`exec`)
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would trigger `SCMP_ACT_KILL_PROCESS`, crashing the process loudly. The
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one addition over the raw-protocol variant was `ioctl` (FIONBIO), which
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KJ's `wrapSocketFd` calls to set non-blocking mode; strace identified it
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as the denied syscall in the first sandboxed run.
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3. **Cap'n Proto two-party RPC over a socketpair stalled** in this
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environment (Cap'n Proto 1.1.0, seccomp 2.6, Debian 13). The server
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received and processed requests (the parse handler ran), but the responses
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never reached the client — both processes blocked on `read` with no
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`write`/`sendmsg` to the socketpair. This is a real integration issue,
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**not** a sandbox issue (it reproduced with the sandbox disabled). It is
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recorded here for M2 to debug with the full event-loop integration; the
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spike uses a raw length-prefixed protocol to measure the channel cost
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without that blocker. The `ipc.capnp` schema is kept for the M2 work. The
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most likely cause is a subtlety in `EzRpcClient(int fd)` / the low-level
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`TwoPartyVatNetwork` over an `AF_UNIX` socketpair end that needs
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investigation with a debugger, not a spike-time detour.
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3. **The Cap'n Proto socketpair stall is RESOLVED.** The original M0 spike
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recorded that `EzRpcServer(int fd, ...)` over a socketpair stalled: the
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server processed requests but responses never reached the client. Root
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cause, confirmed with a standalone reproduction: **`EzRpcServer(int fd,
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...)` expects a LISTENING socket and calls `accept()` on it.** A
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socketpair end is already CONNECTED, so `accept()` fails with `EINVAL`
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("Invalid argument") and the bootstrap never completes — the server
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aborts and the client sees a disconnect. The fix is the low-level path on
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the server side:
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```cpp
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kj::AsyncIoContext io = kj::setupAsyncIo();
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kj::Own<kj::AsyncIoStream> stream = io.lowLevelProvider->wrapSocketFd(fd);
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capnp::TwoPartyVatNetwork network(*stream, capnp::rpc::twoparty::Side::SERVER);
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auto server = capnp::makeRpcServer(network, kj::heap<DocumentProcessImpl>());
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network.onDisconnect().wait(io.waitScope);
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```
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`wrapSocketFd` wraps an already-connected socket as an `AsyncIoStream`
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without calling `accept()`. The client uses `EzRpcClient(int fd)`, which
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*is* designed for an already-connected socket and needs no change. This is
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the shape the production M2 transport uses; the raw length-prefixed
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protocol the spike previously used as a workaround has been removed.
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4. **The bidirectional trust boundary is exercisable.** The UI validates every
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4. **ASan and seccomp don't combine in this spike.** ASan's runtime uses
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`pipe2` (and other syscalls) for its own bookkeeping, which the seccomp
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allow-list denies — so the sandboxed child is killed by SIGSYS under ASan.
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This is an ASan-only artefact (the Release build runs cleanly under the
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sandbox); the spike verifies ASan-cleanliness with the sandbox disabled
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(`FPE_SPIKE_E_NO_SANDBOX=1`), matching the original M0 verification
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approach. The production M2 code uses a hardened allocator + sanitizers in
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CI rather than running ASan inside the sandboxed process.
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5. **ASan caught a use-after-free in the first RPC wiring** — storing a
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`ParseResult::Reader` beyond the lifetime of the `Response` that owns its
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backing message. Fixed by validating the response inside the `Response`'s
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scope. This validates the §7.2 sanitizers-from-day-one posture: the FFI
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and RPC integration code is exactly where lifetime bugs hide.
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6. **The bidirectional trust boundary is exercisable.** The UI validates every
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response field (request id, byte count, ok) and the document process
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bounds-checks every request length — both sides of ADR-0004 are
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demonstrated. The production M2 code fuzzes the UI-side deserializer as a
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@ -92,16 +125,18 @@ Verified clean under ASan+UBSan.
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- **The process split is viable and cheap.** The §2.1 architecture (one
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sandboxed document process per open document, IPC over a local socket) has
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a measured cost that fits the performance budget with enormous headroom. The
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"genuinely painful to retrofit" concern (§14 step 8) is de-risked: the
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a measured cost that fits the performance budget with enormous headroom.
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The "genuinely painful to retrofit" concern (§14 step 8) is de-risked: the
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sandbox is installed after fork, before any untrusted data, and works.
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- **The Cap'n Proto RPC transport is proven over a socketpair.** The M2
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prerequisite (debug the stall) is done: the production transport works under
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the sandbox, and the integration shape is recorded in
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`spike/E_sandbox/DocumentProcess.cpp`. M2 can build the full protocol
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(object model, render tiles, commands) on this foundation.
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- **The sandbox is the security foundation** (ADR-0004). macOS App Sandbox
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and Windows AppContainer land in M1; the Linux seccomp-bpf filter here is
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the template. The §7.1 threat-model row "parser memory corruption →
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sandboxed document process" is addressed at M0, not retrofitted.
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- **Cap'n Proto remains the planned M2 transport** (§2.1); the socketpair
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stall is an M2 integration task, not an architectural risk. The raw
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protocol here is a measurement tool, not the production transport.
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## Reproducing
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@ -114,4 +149,4 @@ FPE_SPIKE_E_NO_SANDBOX=1 build/manual/bin/spike_e_sandbox 1000 1024
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```
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Exit 0 if all requests round-trip under the sandbox, 1 otherwise. Also
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verified clean under ASan+UBSan.
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verified clean under ASan+UBSan (sandbox disabled).
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@ -132,23 +132,51 @@ endif()
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# --- Spike E: sandbox + IPC bring-up (§14 step 8) ---
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# Two-process model (ADR-0004): a sandboxed document process (seccomp-bpf) and
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# a UI process, talking over a socketpair via a length-prefixed binary IPC.
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# a UI process, talking over a socketpair via Cap'n Proto two-party RPC.
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# This is the one thing the plan says is genuinely painful to retrofit, so it
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# is de-risked at M0. Linux-only at this stage (seccomp-bpf); macOS App Sandbox
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# and Windows AppContainer land in M1.
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#
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# An earlier version used Cap'n Proto two-party RPC over the socketpair; the
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# server received and processed requests but the responses never reached the
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# client — a real integration issue recorded in the spike result doc for M2 to
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# debug with the full event-loop integration. The raw length-prefixed protocol
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# measures the channel cost without that blocker. The Cap'n Proto schema
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# (ipc.capnp) is kept for the M2 RPC work.
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# Integration note: the server side uses the low-level TwoPartyVatNetwork +
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# makeRpcServer over wrapSocketFd (NOT EzRpcServer, which calls accept() on a
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# listening socket and fails on a connected socketpair end with EINVAL — the
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# original Spike E stall, now resolved). The client uses EzRpcClient(fd),
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# which is designed for an already-connected socket. See
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# spike/E_sandbox/DocumentProcess.cpp for the full note.
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find_package(PkgConfig QUIET)
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if(PkgConfig_FOUND)
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pkg_check_modules(SECCOMP libseccomp IMPORTED_TARGET)
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pkg_check_modules(CAPNP capnp-rpc capnp IMPORTED_TARGET)
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endif()
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# The capnp compiler is needed to generate the C++ from the schema. It ships
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# alongside the library (capnproto package on Debian); discover it separately so
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# a missing compiler is a clear message rather than a silent skip.
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find_program(CAPNP_EXECUTABLE NAMES capnp capnpc)
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if(TARGET PkgConfig::SECCOMP AND TARGET PkgConfig::CAPNP AND CAPNP_EXECUTABLE)
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# Generate the C++ from the IPC schema with the capnp compiler directly.
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# (We use the raw compiler rather than capnp_generate_cpp() because the
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# Debian CapnProto CMake config hard-requires libatomic via a check that
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# fails on x86-64 where it isn't needed; pkg-config has no such check.)
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set(_e_schema ${CMAKE_CURRENT_SOURCE_DIR}/E_sandbox/ipc.capnp)
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set(_e_gen_dir ${CMAKE_CURRENT_BINARY_DIR}/E_sandbox_generated)
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set(_e_gen_hdr ${_e_gen_dir}/ipc.capnp.h)
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set(_e_gen_src ${_e_gen_dir}/ipc.capnp.c++)
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file(MAKE_DIRECTORY ${_e_gen_dir})
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# --src-prefix strips the given prefix from the input path so the output
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# is written flat into the output dir (ipc.capnp.h / ipc.capnp.c++) rather
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# than mirroring the spike/E_sandbox/ source tree.
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add_custom_command(
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OUTPUT ${_e_gen_hdr} ${_e_gen_src}
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COMMAND ${CAPNP_EXECUTABLE} compile
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--src-prefix=${CMAKE_CURRENT_SOURCE_DIR}/E_sandbox
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-I${CAPNP_INCLUDE_DIRS}
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-oc++:${_e_gen_dir}
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${_e_schema}
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DEPENDS ${_e_schema}
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COMMENT "Generating Cap'n Proto C++ for Spike E IPC schema"
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VERBATIM)
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if(TARGET PkgConfig::SECCOMP)
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add_executable(spike_e_sandbox
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common/SpikeRunner.cpp
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common/SpikeRunner.h
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@ -159,16 +187,22 @@ if(TARGET PkgConfig::SECCOMP)
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E_sandbox/DocumentProcess.h
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E_sandbox/UIProcess.cpp
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E_sandbox/UIProcess.h
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${_e_gen_src}
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)
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target_include_directories(spike_e_sandbox PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
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target_link_libraries(spike_e_sandbox PRIVATE PkgConfig::SECCOMP)
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target_include_directories(spike_e_sandbox PRIVATE
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${CMAKE_CURRENT_SOURCE_DIR}
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${_e_gen_dir})
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target_link_libraries(spike_e_sandbox PRIVATE
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PkgConfig::SECCOMP
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PkgConfig::CAPNP)
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target_compile_features(spike_e_sandbox PRIVATE cxx_std_20)
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freepdfeditor_apply_warnings(spike_e_sandbox)
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freepdfeditor_apply_hardening(spike_e_sandbox)
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else()
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message(STATUS
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"libseccomp not found — Spike E (sandbox) will not be built. "
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"Install libseccomp-dev to enable it.")
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"libseccomp, Cap'n Proto, or the capnp compiler not found — Spike E "
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"(sandbox) will not be built. Install libseccomp-dev, libcapnp-dev, "
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"and capnproto to enable it.")
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endif()
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# --- Spike F: Rust-vs-C++ build-friction probe (ADR-0005 input, §15) ---
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|
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@ -2,59 +2,68 @@
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// SPDX-FileCopyrightText: 2025 ai-ad4 and the FreePDFEditor contributors
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//
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// DocumentProcess.cpp — the sandboxed document process. Installs the seccomp
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// filter, then serves Parse requests over the socketpair fd using a trivial
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// length-prefixed binary protocol.
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// filter, then serves Parse requests over the socketpair fd using Cap'n Proto
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// two-party RPC (the M2 transport, ADR-0004).
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//
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// Protocol (the "parse" operation counts the bytes it was handed):
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// Request: [u64 request_id][u64 payload_len][payload_len bytes]
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// Response: [u64 request_id][u64 byte_count][u8 ok]
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// Integration note (the Spike E stall, now resolved): the server side CANNOT
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// use `EzRpcServer(int fd, ...)` — that constructor expects a LISTENING
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// socket and calls accept() on it. A socketpair end is already CONNECTED, so
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// accept() fails with EINVAL and the bootstrap never completes (the original
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// Spike E stall). The fix is the low-level path: wrap the connected fd with
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// `LowLevelAsyncIoProvider::wrapSocketFd` (which wraps an already-connected
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// socket as an AsyncIoStream), build a `TwoPartyVatNetwork(SIDE_SERVER)` over
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// it, and `makeRpcServer(network, bootstrap)`. This is the shape the
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// production M2 transport uses.
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//
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// The spike's goal (§14 step 8) is to measure the cost of the process split
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// and prove the sandbox works, not to exercise Cap'n Proto. An earlier
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// version used Cap'n Proto two-party RPC over the socketpair; the server
|
||||
// received and processed requests (the parse handler ran) but the responses
|
||||
// never reached the client — a real integration issue recorded in the spike
|
||||
// result doc for M2 to debug with the full event-loop integration. The raw
|
||||
// protocol measures the channel cost without that blocker.
|
||||
// The sandbox is installed BEFORE the KJ event loop runs. The seccomp
|
||||
// allow-list therefore includes the epoll/eventfd/timerfd syscalls the KJ
|
||||
// async I/O layer needs (Sandbox.cpp); the raw-protocol variant only needed
|
||||
// read/write.
|
||||
|
||||
#include "DocumentProcess.h"
|
||||
#include "Sandbox.h"
|
||||
#include "ipc.capnp.h"
|
||||
|
||||
#include <capnp/rpc-twoparty.h>
|
||||
#include <capnp/rpc.h>
|
||||
#include <kj/async-io.h>
|
||||
#include <kj/memory.h>
|
||||
|
||||
#include <cstdint>
|
||||
#include <cstdio>
|
||||
#include <cstdlib>
|
||||
#include <cstring>
|
||||
#include <string>
|
||||
#include <vector>
|
||||
#include <unistd.h>
|
||||
|
||||
namespace proto = freepdfeditor::spike::e;
|
||||
|
||||
namespace freepdfeditor::spike::e {
|
||||
|
||||
namespace {
|
||||
|
||||
// Read exactly n bytes from fd (handles partial reads). Returns false on EOF/error.
|
||||
bool read_exact(int fd, void* buf, std::size_t n)
|
||||
{
|
||||
auto* p = static_cast<char*>(buf);
|
||||
while (n > 0) {
|
||||
ssize_t r = read(fd, p, n);
|
||||
if (r <= 0) return false;
|
||||
p += r; n -= std::size_t(r);
|
||||
// The document-process capability: a trivial "parser" that counts the bytes
|
||||
// it was handed and returns the count. The real M2 protocol is far larger
|
||||
// (object model, render tiles, commands); this measures the channel cost.
|
||||
class DocumentProcessImpl final : public proto::DocumentProcess::Server {
|
||||
public:
|
||||
kj::Promise<void> parse(ParseContext ctx) override {
|
||||
auto req = ctx.getParams().getRequest();
|
||||
// Per ADR-0004 the document process is untrusted: bound-check the
|
||||
// payload length it was handed (defence in depth; the UI also checks).
|
||||
auto data = req.getData();
|
||||
if (data.size() > 16 * 1024 * 1024) { // 16 MiB cap
|
||||
auto r = ctx.getResults().initResult();
|
||||
r.setRequestId(req.getRequestId());
|
||||
r.setOk(false);
|
||||
r.setError("payload exceeds 16 MiB cap");
|
||||
return kj::READY_NOW;
|
||||
}
|
||||
return true;
|
||||
}
|
||||
|
||||
// Write exactly n bytes to fd (handles partial writes). Returns false on error.
|
||||
bool write_exact(int fd, const void* buf, std::size_t n)
|
||||
{
|
||||
const auto* p = static_cast<const char*>(buf);
|
||||
while (n > 0) {
|
||||
ssize_t w = write(fd, p, n);
|
||||
if (w <= 0) return false;
|
||||
p += w; n -= std::size_t(w);
|
||||
auto r = ctx.getResults().initResult();
|
||||
r.setRequestId(req.getRequestId());
|
||||
r.setByteCount(data.size());
|
||||
r.setOk(true);
|
||||
return kj::READY_NOW;
|
||||
}
|
||||
return true;
|
||||
}
|
||||
};
|
||||
|
||||
} // namespace
|
||||
|
||||
|
|
@ -74,23 +83,31 @@ int run_document_process(int fd)
|
|||
std::fprintf(stderr, "[doc] sandbox DISABLED (FPE_SPIKE_E_NO_SANDBOX set)\n");
|
||||
}
|
||||
|
||||
// Serve requests until the UI process closes the channel (EOF on read).
|
||||
for (;;) {
|
||||
std::uint64_t request_id = 0, payload_len = 0;
|
||||
if (!read_exact(fd, &request_id, sizeof(request_id))) break; // EOF
|
||||
if (!read_exact(fd, &payload_len, sizeof(payload_len))) break;
|
||||
// Per ADR-0004 the document process is untrusted: bound-check the
|
||||
// length it sent. The UI also checks, but defence in depth.
|
||||
if (payload_len > 16 * 1024 * 1024) break; // 16 MiB cap
|
||||
std::vector<unsigned char> payload(payload_len);
|
||||
if (!read_exact(fd, payload.data(), payload_len)) break;
|
||||
// Set up the KJ async I/O context. This creates the epoll/eventfd
|
||||
// machinery the event loop needs (all allowed by the seccomp filter).
|
||||
kj::AsyncIoContext io = kj::setupAsyncIo();
|
||||
|
||||
// The "parse": count the bytes.
|
||||
std::uint64_t byte_count = payload_len;
|
||||
std::uint8_t ok = 1;
|
||||
if (!write_exact(fd, &request_id, sizeof(request_id))) break;
|
||||
if (!write_exact(fd, &byte_count, sizeof(byte_count))) break;
|
||||
if (!write_exact(fd, &ok, sizeof(ok))) break;
|
||||
// Wrap the already-connected socketpair end as an AsyncIoStream. This is
|
||||
// the key difference from the stalled EzRpcServer path: wrapSocketFd does
|
||||
// NOT call accept() — it uses the fd as-is for read/write.
|
||||
kj::Own<kj::AsyncIoStream> stream = io.lowLevelProvider->wrapSocketFd(fd);
|
||||
|
||||
// Two-party RPC: the document process is the SERVER side (it serves the
|
||||
// bootstrap capability the UI imports via getMain()).
|
||||
capnp::TwoPartyVatNetwork network(*stream, capnp::rpc::twoparty::Side::SERVER);
|
||||
auto server = capnp::makeRpcServer(network, kj::heap<DocumentProcessImpl>());
|
||||
|
||||
// Run the event loop until the UI process disconnects (onDisconnect
|
||||
// resolves), then return cleanly.
|
||||
auto disconnect = network.onDisconnect().then([]() {
|
||||
std::fprintf(stderr, "[doc] UI disconnected\n");
|
||||
});
|
||||
try {
|
||||
disconnect.wait(io.waitScope);
|
||||
} catch (kj::Exception& e) {
|
||||
std::fprintf(stderr, "[doc] event loop error: %s\n",
|
||||
e.getDescription().cStr());
|
||||
return 1;
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
|
|
|||
|
|
@ -67,6 +67,10 @@ int install_sandbox()
|
|||
allow_syscall(ctx, SCMP_SYS(timerfd_create));
|
||||
allow_syscall(ctx, SCMP_SYS(timerfd_settime));
|
||||
allow_syscall(ctx, SCMP_SYS(dup)); // Cap'n Proto may dup its socket
|
||||
// ioctl(FIONBIO) is used by KJ's wrapSocketFd to set non-blocking mode on
|
||||
// the socketpair end. Allow the syscall; FIONBIO is the only request the
|
||||
// event loop issues on the IPC fd (no TCGETS/SG_ISPTTY etc. on a socket).
|
||||
allow_syscall(ctx, SCMP_SYS(ioctl));
|
||||
|
||||
// Exit / signal.
|
||||
allow_syscall(ctx, SCMP_SYS(exit));
|
||||
|
|
|
|||
|
|
@ -1,12 +1,21 @@
|
|||
// SPDX-License-Identifier: GPL-3.0-or-later
|
||||
// SPDX-FileCopyrightText: 2025 ai-ad4 and the FreePDFEditor contributors
|
||||
//
|
||||
// UIProcess.cpp — the UI process side. Drives the length-prefixed binary IPC
|
||||
// channel, sends Parse requests, and measures round-trip latency. The UI
|
||||
// does no untrusted parsing; it validates the document process's responses
|
||||
// (ADR-0004: bidirectional trust boundary).
|
||||
// UIProcess.cpp — the UI process side. Drives the Cap'n Proto RPC channel,
|
||||
// sends Parse requests, and measures round-trip latency. The UI does no
|
||||
// untrusted parsing; it validates the document process's responses (ADR-0004:
|
||||
// bidirectional trust boundary).
|
||||
//
|
||||
// The client uses `EzRpcClient(int fd)`, which is designed for an
|
||||
// already-connected socket (unlike EzRpcServer, which expects a listening
|
||||
// socket). See DocumentProcess.cpp for the server-side integration note.
|
||||
|
||||
#include "UIProcess.h"
|
||||
#include "ipc.capnp.h"
|
||||
|
||||
#include <capnp/ez-rpc.h>
|
||||
#include <capnp/message.h>
|
||||
#include <kj/array.h>
|
||||
|
||||
#include <algorithm>
|
||||
#include <chrono>
|
||||
|
|
@ -17,90 +26,70 @@
|
|||
#include <vector>
|
||||
#include <unistd.h>
|
||||
|
||||
namespace proto = freepdfeditor::spike::e;
|
||||
|
||||
namespace freepdfeditor::spike::e {
|
||||
|
||||
namespace {
|
||||
|
||||
bool read_exact(int fd, void* buf, std::size_t n)
|
||||
{
|
||||
auto* p = static_cast<char*>(buf);
|
||||
while (n > 0) {
|
||||
ssize_t r = read(fd, p, n);
|
||||
if (r <= 0) return false;
|
||||
p += r; n -= std::size_t(r);
|
||||
}
|
||||
return true;
|
||||
}
|
||||
|
||||
bool write_exact(int fd, const void* buf, std::size_t n)
|
||||
{
|
||||
const auto* p = static_cast<const char*>(buf);
|
||||
while (n > 0) {
|
||||
ssize_t w = write(fd, p, n);
|
||||
if (w <= 0) return false;
|
||||
p += w; n -= std::size_t(w);
|
||||
}
|
||||
return true;
|
||||
}
|
||||
|
||||
} // namespace
|
||||
|
||||
UIResult run_ui_process(int parent_fd, int child_fd,
|
||||
std::size_t n_requests, std::size_t payload_bytes)
|
||||
{
|
||||
(void)child_fd; // the child end is the document process's concern
|
||||
UIResult r{};
|
||||
|
||||
// The payload the UI hands the document process. Sent as a Cap'n Proto
|
||||
// Data field; the document process counts the bytes and returns the count.
|
||||
std::vector<unsigned char> payload(payload_bytes, 0xAB);
|
||||
|
||||
// EzRpcClient(int fd) wraps an already-connected socket — exactly the
|
||||
// socketpair-end shape. It sets up its own KJ EventLoop + WaitScope.
|
||||
capnp::EzRpcClient client(parent_fd);
|
||||
auto& waitScope = client.getWaitScope();
|
||||
proto::DocumentProcess::Client doc =
|
||||
client.getMain().castAs<proto::DocumentProcess>();
|
||||
|
||||
double min_us = 1e18, max_us = 0.0, sum_us = 0.0;
|
||||
std::size_t acked = 0;
|
||||
|
||||
for (std::size_t i = 0; i < n_requests; ++i) {
|
||||
auto t0 = std::chrono::steady_clock::now();
|
||||
|
||||
// Request: [u64 request_id][u64 payload_len][payload]
|
||||
std::uint64_t request_id = static_cast<std::uint64_t>(i);
|
||||
std::uint64_t payload_len = static_cast<std::uint64_t>(payload_bytes);
|
||||
if (!write_exact(parent_fd, &request_id, sizeof(request_id))) {
|
||||
r.error = "write request_id failed at " + std::to_string(i);
|
||||
break;
|
||||
}
|
||||
if (!write_exact(parent_fd, &payload_len, sizeof(payload_len))) {
|
||||
r.error = "write payload_len failed at " + std::to_string(i);
|
||||
break;
|
||||
}
|
||||
if (!write_exact(parent_fd, payload.data(), payload_bytes)) {
|
||||
r.error = "write payload failed at " + std::to_string(i);
|
||||
break;
|
||||
}
|
||||
auto req = doc.parseRequest();
|
||||
req.getRequest().setRequestId(static_cast<std::uint64_t>(i));
|
||||
req.getRequest().setData(kj::ArrayPtr<const kj::byte>(
|
||||
payload.data(), payload.size()));
|
||||
|
||||
// Response: [u64 request_id][u64 byte_count][u8 ok]
|
||||
std::uint64_t resp_id = 0, byte_count = 0;
|
||||
std::uint8_t ok = 0;
|
||||
if (!read_exact(parent_fd, &resp_id, sizeof(resp_id))) {
|
||||
r.error = "read resp_id failed at " + std::to_string(i);
|
||||
break;
|
||||
// The Response owns the message backing the result reader, so it must
|
||||
// stay alive for as long as we read from `resp` (a dangling reader is
|
||||
// a use-after-free — ASan catches it, validating §7.2). Validate the
|
||||
// response inside the scope that owns the Response.
|
||||
bool ok = false;
|
||||
std::string err;
|
||||
std::uint64_t resp_id = 0;
|
||||
std::uint64_t byte_count = 0;
|
||||
try {
|
||||
auto response = req.send().wait(waitScope);
|
||||
auto resp = response.getResult();
|
||||
ok = resp.getOk();
|
||||
if (!ok) {
|
||||
err = "doc returned ok=false: " + std::string(resp.getError().cStr());
|
||||
} else {
|
||||
resp_id = resp.getRequestId();
|
||||
byte_count = resp.getByteCount();
|
||||
}
|
||||
if (!read_exact(parent_fd, &byte_count, sizeof(byte_count))) {
|
||||
r.error = "read byte_count failed at " + std::to_string(i);
|
||||
break;
|
||||
}
|
||||
if (!read_exact(parent_fd, &ok, sizeof(ok))) {
|
||||
r.error = "read ok failed at " + std::to_string(i);
|
||||
break;
|
||||
} catch (kj::Exception& e) {
|
||||
err = "RPC failed: " + std::string(e.getDescription().cStr());
|
||||
}
|
||||
|
||||
auto t1 = std::chrono::steady_clock::now();
|
||||
double us = std::chrono::duration<double, std::micro>(t1 - t0).count();
|
||||
sum_us += us;
|
||||
min_us = std::min(min_us, us);
|
||||
max_us = std::max(max_us, us);
|
||||
|
||||
// Validate the response (ADR-0004: the IPC is a trust boundary in both
|
||||
// directions — the UI never trusts the document process blindly).
|
||||
if (!ok) { r.error = "doc returned ok=false at " + std::to_string(i); break; }
|
||||
if (resp_id != request_id) {
|
||||
if (!ok) {
|
||||
r.error = err + " at " + std::to_string(i);
|
||||
break;
|
||||
}
|
||||
if (resp_id != static_cast<std::uint64_t>(i)) {
|
||||
r.error = "request id mismatch at " + std::to_string(i);
|
||||
break;
|
||||
}
|
||||
|
|
@ -110,6 +99,10 @@ UIResult run_ui_process(int parent_fd, int child_fd,
|
|||
" expected " + std::to_string(payload_bytes);
|
||||
break;
|
||||
}
|
||||
|
||||
sum_us += us;
|
||||
min_us = std::min(min_us, us);
|
||||
max_us = std::max(max_us, us);
|
||||
++acked;
|
||||
}
|
||||
|
||||
|
|
|
|||
|
|
@ -82,7 +82,7 @@ int main(int argc, char** argv)
|
|||
|
||||
freepdfeditor::spike::SpikeResult sr{};
|
||||
sr.spike = "E";
|
||||
sr.name = "sandbox + IPC bring-up (seccomp-bpf, length-prefixed socketpair)";
|
||||
sr.name = "sandbox + IPC bring-up (seccomp-bpf, Cap'n Proto two-party RPC over socketpair)";
|
||||
sr.total = n_requests;
|
||||
sr.passed = r.requests_acked;
|
||||
sr.failed = n_requests - r.requests_acked;
|
||||
|
|
@ -96,7 +96,8 @@ int main(int argc, char** argv)
|
|||
"requests=%zu acked=%zu payload=%zuB "
|
||||
"avg_latency=%.1fus min=%.1fus max=%.1fus wall=%.1fus "
|
||||
"child_exit=%d; seccomp-bpf deny=open/socket/connect/fork/exec, "
|
||||
"allow=memory/read/write/poll/epoll/exit",
|
||||
"allow=memory/read/write/poll/epoll/ioctl/exit; "
|
||||
"transport=Cap'n Proto two-party RPC (wrapSocketFd + TwoPartyVatNetwork)",
|
||||
n_requests, r.requests_acked, payload_bytes,
|
||||
r.avg_latency_us, r.min_latency_us, r.max_latency_us, wall_us,
|
||||
WIFEXITED(status) ? WEXITSTATUS(status) : -1);
|
||||
|
|
|
|||
Loading…
Reference in New Issue