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Fix MacOS multiprocessing by relaxing sandbox (#1808)

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The following test script fails in the codex sandbox:
```
import multiprocessing
from multiprocessing import Lock, Process

def f(lock):
    with lock:
        print("Lock acquired in child process")

if __name__ == '__main__':
    lock = Lock()
    p = Process(target=f, args=(lock,))
    p.start()
    p.join()
```

with 
```
Traceback (most recent call last):
  File "/Users/david.hao/code/codex/codex-rs/cli/test.py", line 9, in <module>
    lock = Lock()
           ^^^^^^
  File "/Users/david.hao/.local/share/uv/python/cpython-3.12.9-macos-aarch64-none/lib/python3.12/multiprocessing/context.py", line 68, in Lock
    return Lock(ctx=self.get_context())
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/david.hao/.local/share/uv/python/cpython-3.12.9-macos-aarch64-none/lib/python3.12/multiprocessing/synchronize.py", line 169, in __init__
    SemLock.__init__(self, SEMAPHORE, 1, 1, ctx=ctx)
  File "/Users/david.hao/.local/share/uv/python/cpython-3.12.9-macos-aarch64-none/lib/python3.12/multiprocessing/synchronize.py", line 57, in __init__
    sl = self._semlock = _multiprocessing.SemLock(
                         ^^^^^^^^^^^^^^^^^^^^^^^^^
PermissionError: [Errno 1] Operation not permitted
```

After reading, adding this line to the sandbox configs fixes things -
MacOS multiprocessing appears to use sem_lock(), which opens an IPC
which is considered a disk write even though no file is created. I
interrogated ChatGPT about whether it's okay to loosen, and my
impression after reading is that it is, although would appreciate a
close look


Breadcrumb: You can run `cargo run -- debug seatbelt --full-auto <cmd>`
to test the sandbox
This commit is contained in:
David Z Hao
2025-08-03 06:59:26 -07:00
committed by GitHub
parent 81bb1c9e26
commit 75eecb656e
2 changed files with 9 additions and 1 deletions
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6
codex-cli/src/utils/agent/sandbox/macos-seatbelt.ts
View File

@@ -147,4 +147,8 @@ const READ_ONLY_SEATBELT_POLICY = `
(sysctl-name "kern.version")
(sysctl-name "sysctl.proc_cputype")
(sysctl-name-prefix "hw.perflevel")
)`.trim();
)
; Added on top of Chrome profile
; Needed for python multiprocessing on MacOS for the SemLock
(allow ipc-posix-sem)`.trim();

4
codex-rs/core/src/seatbelt_base_policy.sbpl
View File

@@ -65,3 +65,7 @@
(sysctl-name "sysctl.proc_cputype")
(sysctl-name-prefix "hw.perflevel")
)
; Added on top of Chrome profile
; Needed for python multiprocessing on MacOS for the SemLock
(allow ipc-posix-sem)