Messages in this thread | | | Subject | Re: [PATCH v7 00/18] Add support for Nitro Enclaves | From | Alexander Graf <> | Date | Wed, 19 Aug 2020 13:15:59 +0200 |
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On 17.08.20 15:09, Andra Paraschiv wrote: > Nitro Enclaves (NE) is a new Amazon Elastic Compute Cloud (EC2) capability > that allows customers to carve out isolated compute environments within EC2 > instances [1]. > > For example, an application that processes sensitive data and runs in a VM, > can be separated from other applications running in the same VM. This > application then runs in a separate VM than the primary VM, namely an enclave. > > An enclave runs alongside the VM that spawned it. This setup matches low latency > applications needs. The resources that are allocated for the enclave, such as > memory and CPUs, are carved out of the primary VM. Each enclave is mapped to a > process running in the primary VM, that communicates with the NE driver via an > ioctl interface. > > In this sense, there are two components: > > 1. An enclave abstraction process - a user space process running in the primary > VM guest that uses the provided ioctl interface of the NE driver to spawn an > enclave VM (that's 2 below). > > There is a NE emulated PCI device exposed to the primary VM. The driver for this > new PCI device is included in the NE driver. > > The ioctl logic is mapped to PCI device commands e.g. the NE_START_ENCLAVE ioctl > maps to an enclave start PCI command. The PCI device commands are then > translated into actions taken on the hypervisor side; that's the Nitro > hypervisor running on the host where the primary VM is running. The Nitro > hypervisor is based on core KVM technology. > > 2. The enclave itself - a VM running on the same host as the primary VM that > spawned it. Memory and CPUs are carved out of the primary VM and are dedicated > for the enclave VM. An enclave does not have persistent storage attached. > > The memory regions carved out of the primary VM and given to an enclave need to > be aligned 2 MiB / 1 GiB physically contiguous memory regions (or multiple of > this size e.g. 8 MiB). The memory can be allocated e.g. by using hugetlbfs from > user space [2][3]. The memory size for an enclave needs to be at least 64 MiB. > The enclave memory and CPUs need to be from the same NUMA node. > > An enclave runs on dedicated cores. CPU 0 and its CPU siblings need to remain > available for the primary VM. A CPU pool has to be set for NE purposes by an > user with admin capability. See the cpu list section from the kernel > documentation [4] for how a CPU pool format looks. > > An enclave communicates with the primary VM via a local communication channel, > using virtio-vsock [5]. The primary VM has virtio-pci vsock emulated device, > while the enclave VM has a virtio-mmio vsock emulated device. The vsock device > uses eventfd for signaling. The enclave VM sees the usual interfaces - local > APIC and IOAPIC - to get interrupts from virtio-vsock device. The virtio-mmio > device is placed in memory below the typical 4 GiB. > > The application that runs in the enclave needs to be packaged in an enclave > image together with the OS ( e.g. kernel, ramdisk, init ) that will run in the > enclave VM. The enclave VM has its own kernel and follows the standard Linux > boot protocol. > > The kernel bzImage, the kernel command line, the ramdisk(s) are part of the > Enclave Image Format (EIF); plus an EIF header including metadata such as magic > number, eif version, image size and CRC. > > Hash values are computed for the entire enclave image (EIF), the kernel and > ramdisk(s). That's used, for example, to check that the enclave image that is > loaded in the enclave VM is the one that was intended to be run. > > These crypto measurements are included in a signed attestation document > generated by the Nitro Hypervisor and further used to prove the identity of the > enclave; KMS is an example of service that NE is integrated with and that checks > the attestation doc. > > The enclave image (EIF) is loaded in the enclave memory at offset 8 MiB. The > init process in the enclave connects to the vsock CID of the primary VM and a > predefined port - 9000 - to send a heartbeat value - 0xb7. This mechanism is > used to check in the primary VM that the enclave has booted. > > If the enclave VM crashes or gracefully exits, an interrupt event is received by > the NE driver. This event is sent further to the user space enclave process > running in the primary VM via a poll notification mechanism. Then the user space > enclave process can exit. > > Thank you. >
This version reads very well, thanks a lot Andra!
Greg, would you mind to have another look over it?
Reviewed-by: Alexander Graf <graf@amazon.com>
Alex
Amazon Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B Sitz: Berlin Ust-ID: DE 289 237 879
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