Add guest package for fetching attestation report via syscall (micros…

…oft#1341) Add `internal/guest/linux package`, which contains linux ioctl definitions. Devicemapper code is refactored to use the new package. Introduce new `amdsevsnp` package with Introduce ioctl wrappers and structs required to fetch attestation report. Validate that `LaunchData` provided to HCS during UVM boot and `HostData` returned as part of attestation report match. Add utility binary to fetch SNP report and update Makefile to support `DEV_BUILD` parameter, which includes test utilities inside LCOW image. Fake attestation report can be used when testing integrations. Signed-off-by: Maksim An <maksiman@microsoft.com>
princepereira · Apr 13, 2022 · 7d44757 · 7d44757
1 parent 5161b37
commit 7d44757
Show file tree

Hide file tree

Showing 7 changed files with 287 additions and 40 deletions.
diff --git a/guest/linux/ioctl.go b/guest/linux/ioctl.go
@@ -0,0 +1,49 @@
+//go:build linux
+// +build linux
+
+// Package linux contains definitions required for making a linux ioctl.
+package linux
+
+import (
+	"os"
+	"unsafe"
+
+	"golang.org/x/sys/unix"
+)
+
+// 32 bits to describe an ioctl:
+// 0-7:   NR (command for a given ioctl type)
+// 8-15:  TYPE (ioctl type)
+// 16-29: SIZE (payload size)
+// 30-31: DIR (direction of ioctl, can be: none/write/read/write-read)
+const (
+	IocWrite    = 1
+	IocRead     = 2
+	IocNRBits   = 8
+	IocTypeBits = 8
+	IocSizeBits = 14
+	IocDirBits  = 2
+
+	IocNRMask    = (1 << IocNRBits) - 1
+	IocTypeMask  = (1 << IocTypeBits) - 1
+	IocSizeMask  = (1 << IocSizeBits) - 1
+	IocDirMask   = (1 << IocDirBits) - 1
+	IocTypeShift = IocNRBits
+	IocSizeShift = IocTypeShift + IocTypeBits
+	IocDirShift  = IocSizeShift + IocSizeBits
+	IocWRBase    = (IocRead | IocWrite) << IocDirShift
+)
+
+// Ioctl makes a syscall described by `command` with data `dataPtr` to device
+// driver file `f`.
+func Ioctl(f *os.File, command int, dataPtr unsafe.Pointer) error {
+	if _, _, err := unix.Syscall(
+		unix.SYS_IOCTL,
+		f.Fd(),
+		uintptr(command),
+		uintptr(dataPtr),
+	); err != 0 {
+		return err
+	}
+	return nil
+}
diff --git a/guest/runtime/hcsv2/hostdata.go b/guest/runtime/hcsv2/hostdata.go
@@ -0,0 +1,34 @@
+//go:build linux
+// +build linux
+
+package hcsv2
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+
+	"github.com/Microsoft/hcsshim/pkg/amdsevsnp"
+)
+
+// validateHostData fetches SNP report (if applicable) and validates `hostData` against
+// HostData set at UVM launch.
+func validateHostData(hostData []byte) error {
+	report, err := amdsevsnp.FetchParsedSNPReport(nil)
+	if err != nil {
+		// For non-SNP hardware /dev/sev will not exist
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return err
+	}
+
+	if bytes.Compare(hostData, report.HostData) != 0 {
+		return fmt.Errorf(
+			"security policy digest %q doesn't match HostData provided at launch %q",
+			hostData,
+			report.HostData,
+		)
+	}
+	return nil
+}
diff --git a/guest/runtime/hcsv2/uvm.go b/guest/runtime/hcsv2/uvm.go
@@ -95,6 +95,15 @@ func (h *Host) SetSecurityPolicy(base64Policy string) error {
 		return err
 	}
 
+	hostData, err := securitypolicy.NewSecurityPolicyDigest(base64Policy)
+	if err != nil {
+		return err
+	}
+
+	if err := validateHostData(hostData[:]); err != nil {
+		return err
+	}
+
 	h.securityPolicyEnforcer = p
 	h.securityPolicyEnforcerSet = true
 

diff --git a/guest/storage/devicemapper/devicemapper.go b/guest/storage/devicemapper/devicemapper.go
@@ -12,6 +12,8 @@ import (
 	"unsafe"
 
 	"golang.org/x/sys/unix"
+
+	"github.com/Microsoft/hcsshim/internal/guest/linux"
 )
 
 // CreateFlags modify the operation of CreateDevice
@@ -28,24 +30,9 @@ var (
 )
 
 const (
-	_IOC_WRITE    = 1
-	_IOC_READ     = 2
-	_IOC_NRBITS   = 8
-	_IOC_TYPEBITS = 8
-	_IOC_SIZEBITS = 14
-	_IOC_DIRBITS  = 2
-
-	_IOC_NRMASK    = ((1 << _IOC_NRBITS) - 1)
-	_IOC_TYPEMASK  = ((1 << _IOC_TYPEBITS) - 1)
-	_IOC_SIZEMASK  = ((1 << _IOC_SIZEBITS) - 1)
-	_IOC_DIRMASK   = ((1 << _IOC_DIRBITS) - 1)
-	_IOC_TYPESHIFT = (_IOC_NRBITS)
-	_IOC_SIZESHIFT = (_IOC_TYPESHIFT + _IOC_TYPEBITS)
-	_IOC_DIRSHIFT  = (_IOC_SIZESHIFT + _IOC_SIZEBITS)
-
 	_DM_IOCTL      = 0xfd
 	_DM_IOCTL_SIZE = 312
-	_DM_IOCTL_BASE = (_IOC_READ|_IOC_WRITE)<<_IOC_DIRSHIFT | _DM_IOCTL<<_IOC_TYPESHIFT | _DM_IOCTL_SIZE<<_IOC_SIZESHIFT
+	_DM_IOCTL_BASE = linux.IocWRBase | _DM_IOCTL<<linux.IocTypeShift | _DM_IOCTL_SIZE<<linux.IocSizeShift
 
 	_DM_READONLY_FLAG       = 1 << 0
 	_DM_SUSPEND_FLAG        = 1 << 1
@@ -132,11 +119,10 @@ func (err *dmError) Error() string {
 	return "device-mapper " + op + ": " + err.Err.Error()
 }
 
-// ioctl issues the specified device-mapper ioctl
-func ioctl(f *os.File, code int, data *dmIoctl) error {
-	_, _, errno := unix.Syscall(unix.SYS_IOCTL, f.Fd(), uintptr(code|_DM_IOCTL_BASE), uintptr(unsafe.Pointer(data)))
-	if errno != 0 {
-		return &dmError{Op: code, Err: errno}
+// devMapperIoctl issues the specified device-mapper ioctl
+func devMapperIoctl(f *os.File, code int, data *dmIoctl) error {
+	if err := linux.Ioctl(f, code|_DM_IOCTL_BASE, unsafe.Pointer(data)); err != nil {
+		return &dmError{Op: code, Err: err}
 	}
 	return nil
 }
@@ -155,7 +141,7 @@ func openMapper() (f *os.File, err error) {
 	}()
 	var d dmIoctl
 	initIoctl(&d, int(unsafe.Sizeof(d)), "")
-	err = ioctl(f, _DM_VERSION, &d)
+	err = devMapperIoctl(f, _DM_VERSION, &d)
 	if err != nil {
 		return nil, err
 	}
@@ -240,7 +226,7 @@ func CreateDevice(name string, flags CreateFlags, targets []Target) (_ string, e
 	var d dmIoctl
 	size := int(unsafe.Sizeof(d))
 	initIoctl(&d, size, name)
-	err = ioctl(f, _DM_DEV_CREATE, &d)
+	err = devMapperIoctl(f, _DM_DEV_CREATE, &d)
 	if err != nil {
 		return "", err
 	}
@@ -256,12 +242,12 @@ func CreateDevice(name string, flags CreateFlags, targets []Target) (_ string, e
 	if flags&CreateReadOnly != 0 {
 		di.Flags |= _DM_READONLY_FLAG
 	}
-	err = ioctl(f, _DM_TABLE_LOAD, di)
+	err = devMapperIoctl(f, _DM_TABLE_LOAD, di)
 	if err != nil {
 		return "", err
 	}
 	initIoctl(&d, size, name)
-	err = ioctl(f, _DM_DEV_SUSPEND, &d)
+	err = devMapperIoctl(f, _DM_DEV_SUSPEND, &d)
 	if err != nil {
 		return "", err
 	}
@@ -306,7 +292,7 @@ func RemoveDevice(name string) (err error) {
 func removeDevice(f *os.File, name string) error {
 	var d dmIoctl
 	initIoctl(&d, int(unsafe.Sizeof(d)), name)
-	err := ioctl(f, _DM_DEV_REMOVE, &d)
+	err := devMapperIoctl(f, _DM_DEV_REMOVE, &d)
 	if err != nil {
 		return err
 	}

diff --git a/tools/snp-report/fake/report.go b/tools/snp-report/fake/report.go
@@ -0,0 +1,57 @@
+//go:build linux
+// +build linux
+
+package fake
+
+import (
+	"encoding/hex"
+	"fmt"
+
+	"github.com/Microsoft/hcsshim/pkg/amdsevsnp"
+)
+
+const fakeSNPReport = "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"
+
+// FetchRawSNPReport hex decodes fakeSNPReport.
+func FetchRawSNPReport() ([]byte, error) {
+	return hex.DecodeString(fakeSNPReport)
+}
+
+// FetchSNPReport returns amdsev.Report object that corresponds to the decoded
+// version of fakeSNPReport. Overrides the resulting report's HostData field
+// with provided `hostData`.
+func FetchSNPReport(hostData string) (amdsevsnp.Report, error) {
+	if hostData == "" {
+		hostData = "28603a3ea835a83bd688b0ec1dcb36b6b8c22412e5b63115b75db8628b989bc5"
+	}
+	hdBytes, err := hex.DecodeString(hostData)
+	if err != nil {
+		return amdsevsnp.Report{}, fmt.Errorf("failed to decode host data: %w", err)
+	}
+	r := amdsevsnp.Report{
+		Version:          1,
+		GuestSVN:         1,
+		Policy:           0x03001f,
+		FamilyID:         "00000000000000000000000000000001",
+		ImageID:          "00000000000000000000000000000001",
+		VMPL:             0,
+		SignatureAlgo:    1,
+		PlatformVersion:  0x2800000000000000,
+		PlatformInfo:     1,
+		AuthorKeyEn:      0,
+		ReportData:       "7ab000a323b3c873f5b81bbe584e7c1a26bcf40dc27e00f8e0d144b1ed2d14f10000000000000000000000000000000000000000000000000000000000000000",
+		Measurement:      "e29af700e85b39996fa38226d2804b78cad746ffef4477360a61b47874bdecd640f9d32f5ff64a55baad3c545484d9ed",
+		HostData:         hdBytes[:],
+		IDKeyDigest:      "98c475ca5f7683e8d351e7e789a1baff19041750567161ad52bf0d152bd76d7c6f313d0a0fd72d0089692c18f5211558",
+		AuthorKeyDigest:  "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
+		ReportID:         "40aea62690b08eb6d680392c9a9b3db56a9b3cc44083b9da31fb88bcfc493407",
+		ReportIDMA:       "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",
+		ReportTCB:        0x2800000000000000,
+		ChipID:           "e6c86796cd44b0bc6b7c0d4fdab33e2807e14b5fc4538b3750921169d97bcf4447c7d3ab2a7c25f74c1641e2885c1011d025cc536f5c9a2504713136c7877f48",
+		CommittedSVN:     "0000000000000000",
+		CommittedVersion: "0000000000000000",
+		LaunchSVN:        "0000000000000000",
+		Signature:        "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",
+	}
+	return r, nil
+}
diff --git a/tools/snp-report/main.go b/tools/snp-report/main.go
@@ -0,0 +1,117 @@
+//go:build linux
+// +build linux
+
+package main
+
+import (
+	"encoding/hex"
+	"flag"
+	"fmt"
+	"os"
+
+	"github.com/Microsoft/hcsshim/internal/tools/snp-report/fake"
+	"github.com/Microsoft/hcsshim/pkg/amdsevsnp"
+)
+
+// verboseReport returns formatted attestation report.
+func verboseReport(r amdsevsnp.Report) string {
+	fieldNameFmt := "%-20s"
+	pretty := ""
+	pretty += fmt.Sprintf(fieldNameFmt+"%08x\n", "Version", r.Version)
+	pretty += fmt.Sprintf(fieldNameFmt+"%08x\n", "GuestSVN", r.GuestSVN)
+	pretty += fmt.Sprintf(fieldNameFmt+"%016x\n", "Policy", r.Policy)
+	pretty += fmt.Sprintf(fieldNameFmt+"%s\n", "FamilyID", r.FamilyID)
+	pretty += fmt.Sprintf(fieldNameFmt+"%s\n", "ImageID", r.ImageID)
+	pretty += fmt.Sprintf(fieldNameFmt+"%08x\n", "VMPL", r.VMPL)
+	pretty += fmt.Sprintf(fieldNameFmt+"%08x\n", "SignatureAlgo", r.SignatureAlgo)
+	pretty += fmt.Sprintf(fieldNameFmt+"%016x\n", "PlatformVersion", r.PlatformVersion)
+	pretty += fmt.Sprintf(fieldNameFmt+"%016x\n", "PlatformInfo", r.PlatformInfo)
+	pretty += fmt.Sprintf(fieldNameFmt+"%08x\n", "AuthorKeyEn", r.AuthorKeyEn)
+	pretty += fmt.Sprintf(fieldNameFmt+"%s\n", "ReportData", r.ReportData)
+	pretty += fmt.Sprintf(fieldNameFmt+"%s\n", "Measurement", r.Measurement)
+	pretty += fmt.Sprintf(fieldNameFmt+"%x\n", "HostData", r.HostData)
+	pretty += fmt.Sprintf(fieldNameFmt+"%s\n", "IDKeyDigest", r.IDKeyDigest)
+	pretty += fmt.Sprintf(fieldNameFmt+"%s\n", "AuthorKeyDigest", r.AuthorKeyDigest)
+	pretty += fmt.Sprintf(fieldNameFmt+"%s\n", "ReportID", r.ReportID)
+	pretty += fmt.Sprintf(fieldNameFmt+"%s\n", "ReportIDMA", r.ReportIDMA)
+	pretty += fmt.Sprintf(fieldNameFmt+"%016x\n", "ReportTCB", r.ReportTCB)
+	pretty += fmt.Sprintf(fieldNameFmt+"%s\n", "ChipID", r.ChipID)
+	pretty += fmt.Sprintf(fieldNameFmt+"%s\n", "CommittedSVN", r.CommittedSVN)
+	pretty += fmt.Sprintf(fieldNameFmt+"%s\n", "CommittedVersion", r.CommittedVersion)
+	pretty += fmt.Sprintf(fieldNameFmt+"%s\n", "LaunchSVN", r.LaunchSVN)
+	pretty += fmt.Sprintf(fieldNameFmt+"%s\n", "Signature", r.Signature)
+	return pretty
+}
+
+func main() {
+	fakeReportFlag := flag.Bool(
+		"fake-report",
+		false,
+		"If true, don't issue an actual syscall to /dev/sev and return a fake predefined report",
+	)
+	hostDataFlag := flag.String(
+		"host-data",
+		"",
+		"Use together with 'fake-report', to set 'HostData' field of fake SNP report.",
+	)
+	reportDataFlag := flag.String(
+		"report-data",
+		"",
+		"Report data to use when fetching SNP attestation report",
+	)
+	binaryFmtFlag := flag.Bool(
+		"binary",
+		false,
+		"Fetch report in binary format",
+	)
+	verbosePrintFlag := flag.Bool(
+		"verbose",
+		false,
+		"Print report in a prettier format",
+	)
+
+	flag.Parse()
+
+	var reportBytes []byte
+	if *reportDataFlag != "" {
+		var err error
+		reportBytes, err = hex.DecodeString(*reportDataFlag)
+		if err != nil {
+			fmt.Printf("failed to decode report data:%s\n", err)
+			os.Exit(1)
+		}
+	}
+	if *binaryFmtFlag {
+		var binaryReport []byte
+		var err error
+		if !*fakeReportFlag {
+			binaryReport, err = fake.FetchRawSNPReport()
+		} else {
+			binaryReport, err = amdsevsnp.FetchRawSNPReport(reportBytes)
+		}
+		if err != nil {
+			fmt.Println(err)
+			os.Exit(1)
+		}
+		fmt.Printf("%x\n", binaryReport)
+		os.Exit(0)
+	}
+
+	var report amdsevsnp.Report
+	var err error
+	if *fakeReportFlag {
+		report, err = fake.FetchSNPReport(*hostDataFlag)
+	} else {
+		report, err = amdsevsnp.FetchParsedSNPReport(reportBytes)
+	}
+	if err != nil {
+		fmt.Printf("failed to fetch SNP report: %s", err)
+		os.Exit(1)
+	}
+
+	if !*verbosePrintFlag {
+		fmt.Printf("%+v\n", report)
+	} else {
+		fmt.Println(verboseReport(report))
+	}
+}