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https://github.com/siderolabs/talos.git
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166d75fe88
The previous flow was using TPM PCR 11 values to bound the policy which means TPM cannot unseal when UKI changes. Now it's fixed to use PCR 7 which is bound to the SecureBoot state (SecureBoot status and Certificates). This provides a full chain of trust bound to SecureBoot state and signed PCR signature. Also the code has been refactored to use PolicyCalculator from the TPM library. Signed-off-by: Noel Georgi <git@frezbo.dev>
88 lines
3.0 KiB
Go
88 lines
3.0 KiB
Go
// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this
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// file, You can obtain one at http://mozilla.org/MPL/2.0/.
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// Package secureboot contains base definitions for the Secure Boot process.
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package secureboot
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// Section is a name of a PE file section (UEFI binary).
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type Section string
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// List of well-known section names.
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const (
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Linux Section = ".linux"
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OSRel Section = ".osrel"
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CMDLine Section = ".cmdline"
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Initrd Section = ".initrd"
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Splash Section = ".splash"
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DTB Section = ".dtb"
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Uname Section = ".uname"
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SBAT Section = ".sbat"
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PCRSig Section = ".pcrsig"
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PCRPKey Section = ".pcrpkey"
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)
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// OrderedSections returns the sections that are measured into PCR.
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//
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// Derived from https://github.com/systemd/systemd/blob/main/src/fundamental/tpm-pcr.h#L23-L36
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// .pcrsig section is omitted here since that's what we are calulating here.
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func OrderedSections() []Section {
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// DO NOT REARRANGE
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return []Section{Linux, OSRel, CMDLine, Initrd, Splash, DTB, Uname, SBAT, PCRPKey}
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}
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// Phase is the phase value extended to the PCR.
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type Phase string
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const (
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// EnterInitrd is the phase value extended to the PCR during the initrd.
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EnterInitrd Phase = "enter-initrd"
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// LeaveInitrd is the phase value extended to the PCR just before switching to machined.
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LeaveInitrd Phase = "leave-initrd"
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// EnterMachined is the phase value extended to the PCR before starting machined.
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// There should be only a signed signature for the enter-machined phase.
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EnterMachined Phase = "enter-machined"
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// StartTheWorld is the phase value extended to the PCR before starting all services.
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StartTheWorld Phase = "start-the-world"
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)
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// PhaseInfo describes which phase extensions are signed/measured.
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type PhaseInfo struct {
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Phase Phase
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CalculateSignature bool
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}
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// OrderedPhases returns the phases that are measured, in order.
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//
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// Derived from https://github.com/systemd/systemd/blob/v253/src/boot/measure.c#L295-L308
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// ref: https://www.freedesktop.org/software/systemd/man/systemd-pcrphase.service.html#Description
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//
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// In the case of Talos disk decryption, happens in machined, so we need to only sign EnterMachined
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// so that machined can only decrypt the disk if the system booted with the correct kernel/initrd/cmdline
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// OrderedPhases returns the phases that are measured.
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func OrderedPhases() []PhaseInfo {
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// DO NOT REARRANGE
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return []PhaseInfo{
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{
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Phase: EnterInitrd,
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CalculateSignature: false,
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},
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{
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Phase: LeaveInitrd,
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CalculateSignature: false,
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},
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{
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Phase: EnterMachined,
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CalculateSignature: true,
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},
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}
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}
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const (
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// UKIPCR is the PCR number where sections except `.pcrsig` are measured.
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UKIPCR = 11
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// SecureBootStatePCR is the PCR number where the secure boot state and the signature are measured.
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// PCR 7 changes when UEFI SecureBoot mode is enabled/disabled, or firmware certificates (PK, KEK, db, dbx, …) are updated.
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SecureBootStatePCR = 7
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)
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