validation_info.go

// Copyright 2023 Meta Platforms, Inc. and affiliates.
//
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// 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
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package validator

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"os"

	"github.com/immune-gmbh/attestation-sdk/pkg/dmidecode"
	"github.com/immune-gmbh/attestation-sdk/pkg/flashrom"
	"github.com/immune-gmbh/attestation-sdk/pkg/measurements"
	xregisters "github.com/immune-gmbh/attestation-sdk/pkg/registers"
	"github.com/immune-gmbh/attestation-sdk/pkg/server/controller/helpers"
	"github.com/immune-gmbh/attestation-sdk/tools/hwsecvalidator/testcase/types"

	"github.com/9elements/converged-security-suite/v2/pkg/bootflow/bootengine"
	"github.com/9elements/converged-security-suite/v2/pkg/bootflow/flows"
	"github.com/9elements/converged-security-suite/v2/pkg/bootflow/subsystems/trustchains/tpm"
	"github.com/9elements/converged-security-suite/v2/pkg/bootflow/systemartifacts/biosimage"
	"github.com/9elements/converged-security-suite/v2/pkg/registers"
	"github.com/9elements/converged-security-suite/v2/pkg/tpmeventlog"
	"github.com/9elements/converged-security-suite/v2/pkg/uefi"
	"github.com/9elements/go-linux-lowlevel-hw/pkg/hwapi"
	"github.com/facebookincubator/go-belt/beltctx"
	"github.com/facebookincubator/go-belt/tool/logger"
	"github.com/google/go-tpm/tpm2"
	"github.com/klauspost/cpuid/v2"
	"github.com/linuxboot/fiano/pkg/intel/metadata/cbnt/cbntbootpolicy"
	"github.com/linuxboot/fiano/pkg/intel/metadata/cbnt/cbntkey"
	"github.com/linuxboot/fiano/pkg/intel/metadata/fit"
	"github.com/marcoguerri/go-tpm-tcti/abrmd"
)

const (
	// EventLogPath is the path used to extract TPM EventLog.
	EventLogPath = `/sys/kernel/security/tpm0/binary_bios_measurements`
)

// Firmware contains all information about a firmware image commonly
// needed in validators.
type Firmware struct {
	UEFI     *uefi.UEFI
	DMITable *dmidecode.DMITable
	Intel    *FirmwareIntelStructs
}

// FirmwareIntelStructs contains structures of a firmware image related to Intel CPUs.
type FirmwareIntelStructs struct {
	FIT fit.Table
	BPM *cbntbootpolicy.Manifest
	KM  *cbntkey.Manifest
}

// ValidationInfo is the prerequisites for any validation work.
type ValidationInfo struct {
	HostBooted                   bool
	SELs                         []types.SEL
	FirmwareCurrent              Firmware
	FirmwareExpected             Firmware
	FirmwareOriginal             Firmware
	FirmwareAlignToCurrentOffset uint64
	ExpectedBootResult           *bootengine.BootProcess
	ExpectedTPMState             *tpm.TPM
	StatusRegisters              registers.Registers
	EventLog                     *tpmeventlog.TPMEventLog
	PCR0Current                  map[tpm2.Algorithm][]byte
}

func parseBytes(b []byte) (Firmware, error) {
	var result Firmware
	var err error

	if result.UEFI, err = uefi.ParseUEFIFirmwareBytes(b); err != nil {
		return Firmware{}, fmt.Errorf("UEFI parsing error: %w", err)
	}

	fwInfo, err := types.NewFirmwareInfoProviderFromUEFI(result.UEFI)
	if err != nil {
		return Firmware{}, fmt.Errorf("could not extract firmware info: %w", err)
	}

	isIntel, err := types.IsArchitecture(fwInfo, cpuid.Intel)
	if err != nil {
		return Firmware{}, fmt.Errorf("could not determine if architecture is Intel: %w", err)
	}

	if isIntel {

		result.Intel = &FirmwareIntelStructs{}
		if result.Intel.FIT, err = fit.GetTable(b); err != nil {
			return Firmware{}, fmt.Errorf("FIT parsing error: %w", err)
		}

		if _, result.Intel.BPM, err = result.Intel.FIT.ParseBootPolicyManifest(b); err != nil {
			return Firmware{}, fmt.Errorf("boot policy manifest (BPM) parsing error: %w", err)
		}

		if _, result.Intel.KM, err = result.Intel.FIT.ParseKeyManifest(b); err != nil {
			return Firmware{}, fmt.Errorf("key manifest (KM) parsing error: %w", err)
		}
	}

	// TODO: consider using of dmidecode.DMITableFromFirmware instead (to avoid double-parsing of the image)
	if result.DMITable, err = dmidecode.DMITableFromFirmwareImage(fwInfo.Firmware().Buf()); err != nil {
		return Firmware{}, ErrParseDMITable{Err: err}
	}

	return result, nil
}

// TestCaseSetup represents the Setup method of a testcase
type TestCaseSetup interface {
	Setup(ctx context.Context, image []byte) error
}

// GetValidationInfo extracts ValidationInfo from the local machine.
func GetValidationInfo(
	ctx context.Context,
	t TestCaseSetup,
	origImage []byte,
	opts types.Options,
) (*ValidationInfo, error) {

	// TODO: Split the function.
	// TODO: Think may be we need dependency injections instead of options.
	optionsConfig := opts.Config()
	var err error
	result := &ValidationInfo{
		HostBooted:  !optionsConfig.HostNotBooted,
		SELs:        optionsConfig.ForceSELEvents,
		PCR0Current: map[tpm2.Algorithm][]byte{},
	}

	// Firmware images

	result.FirmwareOriginal, err = parseBytes(origImage)
	if err != nil {
		return nil, ErrOrigFirmware{Err: ErrParseFirmware{Err: err}}
	}

	// Reproducing the tampered image we expect on this machine.
	//
	// As input we get the original image, but to do the tests we also
	// need to know which tampered image we expect on this machine, so
	// we just reuse the same `Setup` to get the same image as we
	// expect to be already flashed.
	firmwareExpected := make([]byte, len(origImage))
	copy(firmwareExpected, origImage)
	if err = t.Setup(ctx, firmwareExpected); err != nil {
		return nil, ErrSetup{Err: err}
	}

	result.FirmwareExpected, err = parseBytes(firmwareExpected)
	if err != nil {
		return nil, ErrExpectedFirmware{Err: ErrParseFirmware{Err: err}}
	}

	// if optionsConfig.HostNotBooted {
	// 	return result, nil
	// }

	fwInfo, err := types.NewFirmwareInfoProvider(firmwareExpected)
	if err != nil {
		return nil, ErrExpectedFirmware{Err: fmt.Errorf("could not create firmware info provider from expected image: %w", err)}
	}

	isAmdPsb, err := types.SupportsFeature(fwInfo, types.AmdPSBMilan)
	if err != nil {
		return nil, ErrExpectedFirmware{Err: fmt.Errorf("could not determine if expected firmware supports AMD PSB: %w", err)}
	}

	// Status registers

	if regs := optionsConfig.ForceStatusRegisters; regs != nil {
		result.StatusRegisters = regs
	} else if !optionsConfig.HostNotBooted {
		result.StatusRegisters, err = xregisters.LocalRegisters()
		if result.StatusRegisters == nil && err != nil {
			// The && in the condition above is because
			//
			// GetMSRRegister might get not all registers and this is usually
			// fine. So the `err` is not nil, but msrRegisters are not empty and
			// this case is considered good. But if msrRegisters are empty, then
			// definitely something gone wrong (for example not enough permissions
			// to read the registers).
			//
			// TODO: modify GetMSRRegisters API to allow stricter error handling
			//       logic.
			return nil, ErrStatusRegisters{Err: err}
		}
	}

	// Dumping firmware

	if optionsConfig.UseFirmwareExpectedAsCurrent {
		result.FirmwareCurrent = result.FirmwareExpected
	} else if !optionsConfig.HostNotBooted {
		firmwareCurrent, err := flashrom.Dump(ctx, optionsConfig.FlashromOptions...)
		if err != nil {
			return nil, ErrDump{Err: err}
		}

		result.FirmwareCurrent, err = parseBytes(firmwareCurrent)
		if err != nil {
			return nil, ErrCurrentFirmware{Err: ErrParseFirmware{Err: err}}
		}

		result.FirmwareCurrent.DMITable, err = dmidecode.LocalDMITable()
		if err != nil {
			return nil, ErrLocalDMITable{Err: err}
		}
	}

	// TPM EventLog

	log := logger.FromCtx(ctx)

	if evs := optionsConfig.ForceEventLog; evs != nil {
		result.EventLog = &tpmeventlog.TPMEventLog{Events: evs}
	} else if !optionsConfig.HostNotBooted {
		result.EventLog, err = getEventLog(EventLogPath, log)
		if err != nil {
			return nil, ErrEventLog{Err: err, Path: EventLogPath}
		}
	}

	// Intel status registers hacks

	if result.FirmwareCurrent.Intel != nil {
		for idx, statusRegister := range result.StatusRegisters {
			switch statusRegister := statusRegister.(type) {
			case registers.ACMPolicyStatus:
				currentKMID := statusRegister.KMID()
				if currentKMID > result.FirmwareCurrent.Intel.KM.KMID {
					log.Warnf("KMID (%d != %d) is incremented due to Intel's bug https://premiersupport.intel.com/IPS/5003b00001aHC7N", currentKMID, result.FirmwareCurrent.Intel.KM.KMID)
					// KMID represents minor 4 bits of the ACM_POLICY_STATUS, this
					// is why it is corrupted first by these increments.
					//
					// KMID is a 4-bit value, therefore this way we can handle
					// corruptions up to 13 increments (because usually the KMID
					// value is 1-3).
					//
					// See also Intel document #575623 for more details about KMID
					// and ACM_POLICY_STATUS.
					statusRegister -= registers.ACMPolicyStatus(currentKMID - result.FirmwareCurrent.Intel.KM.KMID)
					result.StatusRegisters[idx] = statusRegister
				}
			}
		}
	}

	// Measurements

	// TODO: TPM1.2 does not support SHA256. Fix the code to support TPM1.2.
	algos := []tpm2.Algorithm{tpm2.AlgSHA1, tpm2.AlgSHA256}
	if isAmdPsb {
		// Milan has SHA256 only
		algos = []tpm2.Algorithm{tpm2.AlgSHA256}
	}

	{
		log := log
		if log.Level() > logger.LevelError {
			log = log.WithLevel(logger.LevelError)
		}
		ctx := logger.CtxWithLogger(ctx, log)

		bootResult := measurements.SimulateBootProcess(
			beltctx.WithField(ctx, "subroutine", "measurements.SimulateBootProcess"),
			biosimage.NewFromParsed(result.FirmwareExpected.UEFI),
			result.StatusRegisters,
			flows.Root,
		)
		if err := bootResult.Log.Error(); err != nil {
			return nil, ErrGetPCR0Measurements{Err: fmt.Errorf("unable to simulate boot process: %w", err)}
		}
		result.ExpectedBootResult = bootResult

		tpmInstance, err := tpm.GetFrom(result.ExpectedBootResult.CurrentState)
		if err != nil {
			return nil, ErrGetPCR0Measurements{Err: fmt.Errorf("unable to obtain the simulated TPM state: %w", err)}
		}
		result.ExpectedTPMState = tpmInstance
	}

	// Real PCR0 values

	if optionsConfig.UsePCR0ExpectedAsCurrent {
		for hashAlgo, pcr0Value := range result.ExpectedTPMState.PCRValues[0] {
			result.PCR0Current[tpm2.Algorithm(hashAlgo)] = pcr0Value
		}
	} else if !optionsConfig.HostNotBooted {
		// TODO: add support of TPM1.2
		// TODO: drop abrmd support after it will be dropped in production.

		// Try abrmd first, if failure then try tpmrm.
		var tpmIO io.ReadWriteCloser
		tpmIO, err = abrmd.NewBroker()
		if tpmIO == nil || err != nil {
			var tpm *hwapi.TPM
			tpm, err = hwapi.NewTPM()
			if tpm != nil {
				tpmIO = tpm.RWC
			}
		}
		if err != nil {
			return nil, ErrTPM{Err: fmt.Errorf("unable to open TPM: %w", err)}
		}
		defer func() {
			_ = tpmIO.Close()
		}()

		for _, alg := range algos {
			result.PCR0Current[alg], err = tpm2.ReadPCR(tpmIO, 0, alg)
			if err != nil {
				return nil, ErrTPM{Err: fmt.Errorf("unable to read PCR0 from TPM: %w", err)}
			}
		}
	}

	// Aligning firmwares

	if result.FirmwareCurrent.UEFI != nil {
		var err error

		result.FirmwareExpected.UEFI, result.FirmwareAlignToCurrentOffset, err = helpers.GetAlignedImage(ctx, result.FirmwareExpected.UEFI, result.FirmwareCurrent.UEFI.Buf())
		if err != nil {
			return nil, ErrAlignFirmwares{Err: fmt.Errorf("unable to align the expected firmware to the current one: %w", err)}
		}

		result.FirmwareOriginal.UEFI, _, err = helpers.GetAlignedImage(ctx, result.FirmwareOriginal.UEFI, result.FirmwareCurrent.UEFI.Buf())
		if err != nil {
			return nil, ErrAlignFirmwares{Err: fmt.Errorf("unable to align the original firmware to the current one: %w", err)}
		}
	}

	return result, nil
}

func getEventLog(filepath string, log logger.Logger) (*tpmeventlog.TPMEventLog, error) {
	// We lose eventlog when do kexec in YARD, and this is not a fault
	// of a vendor or NPIs, so no sense to return a validation error here.
	// Just printing a warning and continuing.
	//
	// See also: https://www.internalfb.com/tasks?t=98458790

	// Symptoms that eventlog doesn't exist: no file or empty file
	if _, err := os.Stat(filepath); errors.Is(err, os.ErrNotExist) {
		if log != nil {
			log.Warnf("no EventLog found in '%s'", filepath)
		}
		return nil, nil
	}

	eventLog, err := os.ReadFile(EventLogPath)
	if err != nil {
		return nil, fmt.Errorf("unable to read eventlog conents: %w", err)
	}

	if len(eventLog) == 0 {
		if log != nil {
			log.Warnf("EventLog file is empty")
		}
		return nil, nil
	}

	return tpmeventlog.Parse(bytes.NewReader(eventLog))
}