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Takaya Saeki e299f02d3f seccomp: allow clone3 to video_device on x86 
Recently, common_device.policy added clone3. It is included by most
devices through include, but the video device missed it since it doesn't
include common_device.policy due to some policy override.

This commit adds clone3 to the policy of the video device to fix that
problem. With this fix, the video device successfully runs in the
sandbox on newer kernels.

BUG=None
TEST=a vm with a video device launches with the sandbox enabled

Change-Id: Idc2dee824e863f3ee43cfd6ce76656e36d6200c0
Reviewed-on: https://chromium-review.googlesource.com/c/crosvm/crosvm/+/4053447
Reviewed-by: Keiichi Watanabe <keiichiw@chromium.org>
Commit-Queue: Takaya Saeki <takayas@chromium.org>
2022-11-24 09:40:27 +00:00
..
aarch64 seccomp: allow process_vm_readv to video_device on aarch64 2022-11-18 22:42:55 +00:00
arm Generate constants.json offline 2022-11-02 00:13:08 +00:00
x86_64 seccomp: allow clone3 to video_device on x86 2022-11-24 09:40:27 +00:00
generate_constants.sh Generate constants.json offline 2022-11-02 00:13:08 +00:00
README.md seccomp: define naming rules for policy files 2022-06-17 04:35:09 +00:00

README.md

Policy files for crosvm

This folder holds the seccomp policies for crosvm devices, organized by architecture.

Each crosvm device can run within its owned jailed process. A jailed process is only able to perform the system calls specified in the seccomp policy file the jail has been created with, which improves security as a rogue process cannot perform any system call it wants.

Each device can run from different contexts, which require a different set of authorized system calls. This file explains how the policy files are named in order to allow these various scenario.

Naming conventions

Since Minijail only allows for one level of policy inclusion, we need to be a little bit creative in order to minimize policy duplication.

  • common_device.policy contains a set of syscalls that are common to all devices, and is never loaded directly - only included from other policy files.
  • foo.policy contains the set of syscalls that device foo is susceptible to use, regardless of the underlying virtio transport. This policy is also never loaded directly.
  • foo_device.policy is the policy that is loaded when device foo is used as an in-VMM (i.e. regular virtio) device. It will generally simply include common_device.policy as well as foo.policy.

When using vhost-user, the virtio protocol needs to be sent over a different medium, e.g. a Unix socket. Supporting this transport requires some extra system calls after the device is jailed, and thus dedicated policies:

  • vhost_user.policy contains the set of syscalls required by the regular (i.e. socket-based) vhost-user listener. It is never loaded directly.
  • vvu.policy contains the set of syscalls required by the VFIO-based vhost-user (aka Virtio-Vhost-User) listener. It is also never loaded directly.
  • foo_device_vhost_user.policy is the policy that is loaded when device foo is used as a regular vhost-user device. It will generally include common_device.policy, vhost_user.policy and foo.policy.
  • foo_device_vvu.policy is the policy that is loaded when device foo is used as a VVU device. It will generally include common_device.policy, vvu.policy and foo.policy.