From dbc5dd145a037c131ecfb63404ac528eebb95b9e Mon Sep 17 00:00:00 2001 From: Marcela Melara Date: Thu, 29 Aug 2024 15:58:42 -0700 Subject: [PATCH] Update L1 and L2 per review comments Signed-off-by: Marcela Melara --- docs/spec/draft/attested-build-env-levels.md | 52 +++++++++++--------- 1 file changed, 29 insertions(+), 23 deletions(-) diff --git a/docs/spec/draft/attested-build-env-levels.md b/docs/spec/draft/attested-build-env-levels.md index 0cce4701c..95eacd875 100644 --- a/docs/spec/draft/attested-build-env-levels.md +++ b/docs/spec/draft/attested-build-env-levels.md @@ -32,7 +32,7 @@ environment, and the compute platform they used. | Track/Level | Requirements | Focus | ------------- | ------------ | ----- | [BuildEnv L0] | (none) | (n/a) -| [BuildEnv L1] | Build image provenance exists | Tampering during build image distribution +| [BuildEnv L1] | Signed build image provenance exists | Tampering during build image distribution | [BuildEnv L2] | Attested build environment deployment | Tampering via the build platform's control plane | [BuildEnv L3] | Hardware-authenticated build environment | Tampering via the compute platform's host interface | [BuildEnv L4] | Encrypted build environment | Tampering and data leaks by the build platform or compute platform during the build @@ -66,7 +66,7 @@ A typical build environment will go through the following lifecycle: the SLSA Environment track, the build platform attests to the binding between a build environment and *build ID*. 4. *Build execution*: Finally, the *build executor* running within the -environment executes the tenant's build definition. + environment executes the tenant's build definition. ### Definitions @@ -85,6 +85,7 @@ and roles: | Host interface | The component in the compute platform that the hosted build platform uses to request resources for deploying new build environments, i.e., the VMM/hypervisor or container orchestrator. | Boot process | In the context of builds, the process of loading and executing the layers of firmware and/or software needed to start up a build environment on the build platform. | Measurement | The cryptographic hash of some component or system state in the build environment, including software binaries, configuration, or initialized run-time data. +| Quote | Hardware-signed data that contains one or more hardware-generated measurements. Quotes may additionally include nonces for replay protection, firmware information, or other platform metadata. | Reference value | A specific measurement used as the good known value for a given build environment component or state. TODO: Disambiguate similar terms (e.g., image, build job, build runner) @@ -98,7 +99,7 @@ TODO The primary purpose of the Build Environment (BuildEnv) track is to enable [auditing] that a build was run in the expected execution context. -The lowest level only requires SLSA [Build L1] (or higher) Provenance to +The lowest level only requires SLSA [Build L2] Provenance to exist for the build image, while higher levels provide increasing auditability of the build environment's properties and integrity of the generated provenance attestations. The highest levels introduce further @@ -108,7 +109,8 @@ computing base of a build. Software producers and third-party auditors can check attestations generated by the build image producer and build platform against the expected properties for a given build environment. This enables any party to detect -[several classes] of supply chain threats originating the build environment. +[several classes] of supply chain threats originating in the build +environment. As in the Build track, the exact implementation of this track is determined by the build platform provider, whether they are a commercial CI/CD service, @@ -147,7 +149,7 @@ n/a
-### BuildEnv L1: Build image provenance exists +### BuildEnv L1: Signed build image provenance exists
Summary
@@ -163,17 +165,20 @@ integrity for build environments at the time of build image distrbution.
Requirements
- Build Image Producer: - - MUST automatially generate SLSA [Build L1] or higher + - MUST automatially generate SLSA [Build L2] or higher Provenance for created build images (i.e., VM or container images). - MUST allow independent automatic verification of a build image's SLSA - Provenance. If the full Provenance document cannot be distributed, for - example due to intellectual property concerns, a [VSA] asserting the - build image's SLSA Provenance MUST be distributed instead. + Provenance. If the build image artifact cannot be published, for example + due to intellectual property concerns, an attestation asserting the + expected hash value of the build image MUST be generated and distributed + instead (e.g., using [SCAI] or a [Release Attestation]). If the full + Provenance document cannot be disclosed, a [VSA] asserting the build + image's SLSA Provenance MUST be distributed instead. - Build Platform: - MUST meet SLSA [Build L2] requirements. - Prior to deployment of a new build environment, the SLSA Provenance - for the selected build image MUST be automatically verified. + for the selected build image SHOULD be automatically verified.
Benefits
@@ -192,7 +197,7 @@ source and build process. The build environment is measured and authenticated prior to dispatching any builds, attesting to the integrity of initial state of the environment -when it's deployed by the build paltform. +when it's deployed by the build platform.
Intended for
@@ -204,7 +209,7 @@ a clean, known good state. All of [BuildEnv L1], plus: - Build Image Producer: - - Build images MUST be created via a SLSA [Build L2] or higher build + - Build images MUST be created via a SLSA [Build L3] or higher build process. - MUST add support in the build image to: - Automatically check build image components against their @@ -224,11 +229,14 @@ All of [BuildEnv L1], plus: - Build Platform Requirements: - MUST meet SLSA [Build L3] requirements. - - Prior to deployment of a new build environment, a signed attestation - to the verification of the build image's SLSA Provenance MUST be - automatically generated and distributed (e.g., via a [VSA]). + - Prior to deployment of a new build environment, the SLSA Provenance + for the selected build image MUST be automatically verified. A signed + attestation to the verification of the build image's SLSA Provenance + MUST be automatically generated and distributed (e.g., via a [VSA]). - Prior to dispatching a tenant's build to a deployed environment, its - initial state attestation MUST be automatically verified. + initial state attestation MUST be automatically verified. A signed + attestation binding the tenant's build ID to the verified initial state + of the selected build environment MUST be generated and distributed.
Benefits
@@ -261,9 +269,9 @@ a known good environment. All of [BuildEnv L2], plus: +**TODO:** These requirements need to be re-formulated. + - Build Image Producer: - - Build images MUST be created via a SLSA [Build L3] or higher build - process. - MUST add support in the build image to: - Use trusted hardware to check build image component reference values and integrity of the build environment startup. @@ -274,11 +282,9 @@ All of [BuildEnv L2], plus: - Use trusted hardware to sign all build image-generated attestations. -- Build Platform Requirements: - - MUST meet SLSA [Build L3] requirements. - - Prior to assigning a build ID to tenant's build, a signed attestation - to the verification of the selected build environment initial state - attestations MUST be generated and distributed. +- Build Platform Requirements: TODO + +- Compute Platform Requirements: TODO
Benefits