Fix codex-host profile: capability allow + netlink (bwrap needs both)

Two bwrap failures found by live host tasks, both in the
AppArmor profile (not in codex or the worker):
1. deny capability sys_admin (etc.) breaks bwrap at userns
   creation: codex-host with the deny list failed, the same
   profile with capability, allowed it. codexsvc holds no host
   capabilities, so the allow only covers fake-root caps inside
   bwrap's own user namespace (scoped, harmless to the host);
   network/ptrace/file denies still hold independently.
2. bwrap brings up loopback in its new net namespace via a
   NETLINK_ROUTE socket: without network netlink raw, codex
   workspace-write fails with 'Failed to bind NETLINK_ROUTE
   socket' and no tool runs. And a bare 'deny network raw'
   overrides the netlink allow (deny wins over allow), so the
   raw deny must name inet/inet6 explicitly (verified by an
   isolated netlink bind test under each profile variant).
README correction in the same change: codex workspace-write
does NOT isolate /tmp -- an agent /tmp write lands on host
/tmp (verified). The verified boundary is: own worktree
writable, everything else read-only, /tmp shared.

cloud/README.md

@@ -514,16 +514,22 @@ interrupted 且终态任务 cancel 返回 400、心跳后 sweep 不扫刚心跳
   `host-config-host.json`（sandbox workspace-write，state 独立
   为 work/host-state-host.json），以 `aa-exec -p codex-host`
   运行（见 `deploy/apparmor/codex-host`：docker-codex 基础 +
-  userns/mount/pivot_root，仍禁 raw/ptrace/危险 capability），
+  userns/mount/pivot_root，仍禁 raw 网络与 ptrace；capability
+  必须放行——codexsvc 本身无宿主 capability，放行的只是 bwrap
+  的 userns 内假 root capability，实测 deny sys_admin 会让
+  bwrap 在 userns 创建处失败），
   并带 `HTTP(S)_PROXY=http://127.0.0.1:8888` 让 relay/git 出口
   同样走 Tinyproxy 白名单。路由靠任务的 executor 字段
   （POST /tasks 已支持 local/docker/cloud）：宿主 worker 必须
   开 `--claim-executor-only`，只认领 executor='local' 的任务，
   绝不抢 executor 为 NULL 的任务（否则会把本该进 Docker 的
   任务拉到宿主上跑，丢了 Docker 外层）。宿主任务放弃 Docker
-  外层（无容器、无租户挂载/网络隔离），换来的是 bwrap 内层
-  （agent 只能写自己 worktree，/tmp 是隔离的 tmpfs，写不到
-  宿主 /tmp；其它任务 worktree 与宿主文件同样不可见）。
+  外层（无容器、无租户挂载/网络隔离），换来的是 bwrap 内层。
+  实测过的沙箱边界（诚实版）：agent 只能写自己 worktree，
+  写宿主其它目录与其它任务 worktree 均被挡（报文件系统只读）；
+  但 /tmp 不隔离——agent 写 /tmp 会落到宿主 /tmp 上（codex
+  的 workspace-write 不把 /tmp 做成隔离 tmpfs），所以 /tmp
+  是任务间的共享区，不能当作隔离边界。
 - 网络白名单的诚实边界：docker run 默认 bridge 网络，本执行
   器不做 egress 白名单——真正的“只放行模型 API”需要宿主防火
   墙或代理规则，那是部署项，不是本轮代码假装做到的，不要宣称

cloud/tests/test_host_sandbox_routing.py

@@ -93,6 +93,22 @@ class HostConfigProfileTestCase(unittest.TestCase):
         self.assertIn("pivot_root,", text)
         self.assertNotIn("deny mount,", text)
         self.assertNotIn("deny umount,", text)
+        # bwrap 还需要 userns 内的 capability（实测：deny
+        # capability sys_admin 会让 bwrap 在 userns 创建处失败，
+        # 而 capability, 允许则成功；codexsvc 本身无宿主
+        # capability，所以这里允许的只是 userns 内的假 root
+        # capability，不授予宿主特权）。
+        self.assertIn("capability,", text)
+        self.assertNotIn("deny capability sys_admin,", text)
+        # bwrap 还需要 netlink（在新网络命名空间里拉起 loopback；
+        # 缺了会报 Failed to bind NETLINK_ROUTE socket，且任何
+        # 工具都跑不起来）。注意 AppArmor 里 deny 优先于 allow，
+        # 所以 raw 的 deny 必须写明 inet/inet6，不能写裸的
+        # deny network raw（那样会连 netlink raw 一起挡掉，
+        # 已用隔离 netlink bind 实测验证）。
+        self.assertIn("network netlink raw,", text)
+        self.assertIn("deny network inet raw,", text)
+        self.assertNotIn("deny network raw,", text)
 
 
 if __name__ == "__main__":

deploy/apparmor/codex-host

@@ -38,29 +38,31 @@ profile codex-host flags=(attach_disconnected,mediate_deleted) {
   network inet dgram,
   network inet6 stream,
   network inet6 dgram,
-  deny network raw,
+  # bwrap brings up loopback in its new network namespace via a
+  # NETLINK_ROUTE socket (verified 2026-10-26: without this,
+  # codex workspace-write fails with "bwrap: loopback: Failed
+  # to bind NETLINK_ROUTE socket: Permission denied" and no tool
+  # runs at all). CAREFUL: a bare "deny network raw" would
+  # override this allow (deny wins over allow in AppArmor) and
+  # break netlink too -- verified by isolated netlink bind test.
+  # So the raw deny must name inet/inet6 explicitly, leaving
+  # netlink raw allowed.
+  network netlink raw,
+  deny network inet raw,
+  deny network inet6 raw,
 
-  capability chown,
-  capability dac_override,
-  capability fsetid,
-  capability fowner,
-  capability mknod,
-  capability net_bind_service,
-  capability setfcap,
-  capability setgid,
-  capability setpcap,
-  capability setuid,
-  capability sys_chroot,
-  deny capability sys_admin,
-  deny capability sys_ptrace,
-  deny capability net_admin,
-  deny capability net_raw,
-  deny capability sys_module,
-  deny capability sys_rawio,
-  deny capability sys_boot,
-  deny capability sys_time,
-  deny capability mac_admin,
-  deny capability mac_override,
+  # Capabilities: bwrap NEEDS userns-scoped capabilities (verified
+  # 2026-10-26: codex-host with deny capability sys_admin etc.
+  # made bwrap fail at userns creation, while the same profile
+  # with capability, allowed it). This is safe for an unprivileged
+  # user: codexsvc holds NO host capabilities, so the only caps
+  # this allows are fake-root caps inside bwrap's own user
+  # namespace (scoped to that namespace, harmless to the host).
+  # The profile's other denies still hold independently: raw
+  # network is gated by network rules, ptrace by ptrace rules,
+  # /proc/sys writes by file rules -- allowing caps does not
+  # void any of them.
+  capability,
 
   # bwrap needs these (docker-codex denies them).
   userns,