红帽全球峰会第 7 章 Configuring RHEL on Public Cloud Platforms with AMD SEV SNP
AMD Secure Encrypted Virtualization with Secure Nested Paging (SEV-SNP) aims to prevent VM integrity-based attacks and reduce the dangers of memory integrity violations. For the secure boot process, AMD processors offer three hardware-based security mechanisms; Secure Encrypted Virtualization (SEV), SEV Encrypted State (SEV-ES), and SEV Secure Nested Paging (SEV-SNP).
- SEV: The SEV mechanism encrypts virtual machine (VM) memory to prevent the hypervisor from accessing VM data.
- SEV-ES: SEV with Encrypted State (SEV-ES) extends SEV by encrypting CPU register states. This mechanism prevents the hypervisor from accessing or modifying VM CPU registers. Despite providing isolation between hypervisor and VM, it is still vulnerable to memory integrity attacks.
SEV-SNP: SEV-SNP is an enhancement to SEV-ES that adds memory integrity protection along with VM encryption. This mechanism prevents the hypervisor from modifying page tables to redirect VM memory access, protecting against replay attacks and memory tampering.
注意Before deploying Red Hat Enterprise Linux (RHEL) on a public cloud platform, always check with the corresponding cloud service provider for the support status and certification of the particular RHEL instance type.
7.1. Properties of SEV-SNP
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Secure Processor: The AMD
EPYCprocessor integrates a Secure Processor (SP) subsystem. AMD SP is a dedicated hardware component to manage keys and encryption operations. - Memory Integrity: For managing virtualization and isolation, memory management unit (MMU) utilizes page tables to translate virtual addresses to guest-physical addresses. SEV-SNP uses nested page tables for translating guest-physical addresses to host-physical addresses. Once nested page tables are defined, the hypervisor or host cannot alter page tables to modify the VM into accessing different pages, resulting in protection of memory integrity. SEV-SNP uses this method to offer protection against replay attacks and malicious modifications to VM memory.
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Memory Encryption: The AMD
EPYCprocessor hides the memory encryption key, which remains hidden from both host and VM. Attestation report for verification: A CPU-generated report about RHEL instance information in an authorized cryptographic format. This process confirms the authenticity and reliability of the initial CPU and memory state of the RHEL instance and AMD processor.
注意Even if a hypervisor creates the primary memory and CPU register state of the VM, they remain hidden and inaccessible to the hypervisor after initialization of that VM.
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