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Tsirkin" , marcandre.lureau@gmail.com, kraxel@redhat.com, Stefan Hajnoczi Subject: [PATCH v3 1/3] hw/virtio: check owner for removing objects Date: Tue, 9 Jan 2024 13:56:12 +0100 Message-ID: <20240109125614.220293-2-aesteve@redhat.com> In-Reply-To: <20240109125614.220293-1-aesteve@redhat.com> References: <20240109125614.220293-1-aesteve@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.6 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=aesteve@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -45 X-Spam_score: -4.6 X-Spam_bar: ---- X-Spam_report: (-4.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.493, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1704805060645100005 Content-Type: text/plain; charset="utf-8" Shared objects lack spoofing protection. For VHOST_USER_BACKEND_SHARED_OBJECT_REMOVE messages received by the vhost-user interface, any backend was allowed to remove entries from the shared table just by knowing the UUID. Only the owner of the entry shall be allowed to removed their resources from the table. To fix that, add a check for all *SHARED_OBJECT_REMOVE messages received. A vhost device can only remove TYPE_VHOST_DEV entries that are owned by them, otherwise skip the removal, and inform the device that the entry has not been removed in the answer. Signed-off-by: Albert Esteve Acked-by: Stefan Hajnoczi --- docs/interop/vhost-user.rst | 4 +++- hw/virtio/vhost-user.c | 21 +++++++++++++++++++-- 2 files changed, 22 insertions(+), 3 deletions(-) diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst index 9f1103f85a..60ec2c9d48 100644 --- a/docs/interop/vhost-user.rst +++ b/docs/interop/vhost-user.rst @@ -1839,7 +1839,9 @@ is sent by the front-end. When the ``VHOST_USER_PROTOCOL_F_SHARED_OBJECT`` protocol feature has been successfully negotiated, this message can be submitted by the backend to remove themselves from to the virtio-dmabuf shared - table API. The shared table will remove the back-end device associated w= ith + table API. Only the back-end owning the entry (i.e., the one that first = added + it) will have permission to remove it. Otherwise, the message is ignored. + The shared table will remove the back-end device associated with the UUID. If ``VHOST_USER_PROTOCOL_F_REPLY_ACK`` is negotiated, and the back-end sets the ``VHOST_USER_NEED_REPLY`` flag, the front-end must res= pond with zero when operation is successfully completed, or non-zero otherwis= e. diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index f214df804b..1c3f2357be 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -1611,11 +1611,27 @@ vhost_user_backend_handle_shared_object_add(struct = vhost_dev *dev, } =20 static int -vhost_user_backend_handle_shared_object_remove(VhostUserShared *object) +vhost_user_backend_handle_shared_object_remove(struct vhost_dev *dev, + VhostUserShared *object) { QemuUUID uuid; =20 memcpy(uuid.data, object->uuid, sizeof(object->uuid)); + switch (virtio_object_type(&uuid)) { + case TYPE_VHOST_DEV: + { + struct vhost_dev *owner =3D virtio_lookup_vhost_device(&uuid); + if (owner =3D=3D NULL || dev !=3D owner) { + /* Not allowed to remove non-owned entries */ + return 0; + } + break; + } + default: + /* Not allowed to remove non-owned entries */ + return 0; + } + return virtio_remove_resource(&uuid); } =20 @@ -1794,7 +1810,8 @@ static gboolean backend_read(QIOChannel *ioc, GIOCond= ition condition, ret =3D vhost_user_backend_handle_shared_object_add(dev, &payload.= object); break; case VHOST_USER_BACKEND_SHARED_OBJECT_REMOVE: - ret =3D vhost_user_backend_handle_shared_object_remove(&payload.ob= ject); + ret =3D vhost_user_backend_handle_shared_object_remove(dev, + &payload.obje= ct); break; case VHOST_USER_BACKEND_SHARED_OBJECT_LOOKUP: ret =3D vhost_user_backend_handle_shared_object_lookup(dev->opaque= , ioc, --=20 2.43.0