[PATCH v2 00/18] Add support for Nitro Enclaves

Andra Paraschiv
2020-05-22T06:30:10Z

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 CPU, 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).

How does all gets to an enclave VM running on the host?

There is a NE emulated PCI device exposed to the primary VM. The driver for this
new PCI device is included in the current patch series.

The ioctl logic is mapped to PCI device commands e.g. the NE_START_ENCLAVE ioctl
maps to an enclave start PCI command or the KVM_SET_USER_MEMORY_REGION maps to
an add memory 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.

An enclave communicates with the primary VM via a local communication channel,
using virtio-vsock [2]. 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.

The following patch series covers the NE driver for enclave lifetime management.
It provides an ioctl interface to the user space and includes the NE PCI device
driver that is the means of communication with the hypervisor running on the
host where the primary VM and the enclave are launched.

The proposed solution is following the KVM model and uses KVM ioctls to be able
to create and set resources for enclaves. Additional NE ioctl commands, besides
the ones provided by KVM, are used to start an enclave and get memory offset for
in-memory enclave image loading.

Thank you.

Andra

[1] https://aws.amazon.com/ec2/nitro/nitro-enclaves/
[2] http://man7.org/linux/man-pages/man7/vsock.7.html

---

Patch Series Changelog

The patch series is built on top of v5.7-rc6.

v1 -> v2

* Rebase on top of v5.7-rc6.
* Adapt codebase based on feedback from v1.
* Update ioctl number definition - major and minor.
* Add sample / documentation for the ioctl interface basic flow usage.
* Update cover letter to include more context on the NE overall.
* Add fix for the enclave / vcpu fd creation error cleanup path.
* Add fix reported by kbuild test robot <lkp@intel.com>.
* v1: https://lore.kernel.org/lkml/20200421184150.68011-1-andraprs@amazon.com/

---

Andra Paraschiv (18):
nitro_enclaves: Add ioctl interface definition
nitro_enclaves: Define the PCI device interface
nitro_enclaves: Define enclave info for internal bookkeeping
nitro_enclaves: Init PCI device driver
nitro_enclaves: Handle PCI device command requests
nitro_enclaves: Handle out-of-band PCI device events
nitro_enclaves: Init misc device providing the ioctl interface
nitro_enclaves: Add logic for enclave vm creation
nitro_enclaves: Add logic for enclave vcpu creation
nitro_enclaves: Add logic for enclave image load metadata
nitro_enclaves: Add logic for enclave memory region set
nitro_enclaves: Add logic for enclave start
nitro_enclaves: Add logic for enclave termination
nitro_enclaves: Add Kconfig for the Nitro Enclaves driver
nitro_enclaves: Add Makefile for the Nitro Enclaves driver
nitro_enclaves: Add sample for ioctl interface usage
nitro_enclaves: Add overview documentation
MAINTAINERS: Add entry for the Nitro Enclaves driver

Documentation/nitro_enclaves/ne_overview.txt | 86 ++
.../userspace-api/ioctl/ioctl-number.rst | 5 +-
MAINTAINERS | 13 +
drivers/virt/Kconfig | 2 +
drivers/virt/Makefile | 2 +
drivers/virt/nitro_enclaves/Kconfig | 28 +
drivers/virt/nitro_enclaves/Makefile | 23 +
drivers/virt/nitro_enclaves/ne_misc_dev.c | 1152 +++++++++++++++++
drivers/virt/nitro_enclaves/ne_misc_dev.h | 121 ++
drivers/virt/nitro_enclaves/ne_pci_dev.c | 717 ++++++++++
drivers/virt/nitro_enclaves/ne_pci_dev.h | 266 ++++
include/linux/nitro_enclaves.h | 23 +
include/uapi/linux/nitro_enclaves.h | 77 ++
samples/nitro_enclaves/.gitignore | 2 +
samples/nitro_enclaves/Makefile | 28 +
.../include/linux/nitro_enclaves.h | 23 +
.../include/uapi/linux/nitro_enclaves.h | 77 ++
samples/nitro_enclaves/ne_ioctl_sample.c | 502 +++++++
18 files changed, 3146 insertions(+), 1 deletion(-)
create mode 100644 Documentation/nitro_enclaves/ne_overview.txt
create mode 100644 drivers/virt/nitro_enclaves/Kconfig
create mode 100644 drivers/virt/nitro_enclaves/Makefile
create mode 100644 drivers/virt/nitro_enclaves/ne_misc_dev.c
create mode 100644 drivers/virt/nitro_enclaves/ne_misc_dev.h
create mode 100644 drivers/virt/nitro_enclaves/ne_pci_dev.c
create mode 100644 drivers/virt/nitro_enclaves/ne_pci_dev.h
create mode 100644 include/linux/nitro_enclaves.h
create mode 100644 include/uapi/linux/nitro_enclaves.h
create mode 100644 samples/nitro_enclaves/.gitignore
create mode 100644 samples/nitro_enclaves/Makefile
create mode 100644 samples/nitro_enclaves/include/linux/nitro_enclaves.h
create mode 100644 samples/nitro_enclaves/include/uapi/linux/nitro_enclaves.h
create mode 100644 samples/nitro_enclaves/ne_ioctl_sample.c

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