mirror of
https://github.com/google/go-attestation.git
synced 2024-12-21 05:53:25 +00:00
372 lines
14 KiB
Go
372 lines
14 KiB
Go
package internal
|
|
|
|
import (
|
|
"bytes"
|
|
"encoding/binary"
|
|
"errors"
|
|
"fmt"
|
|
"io"
|
|
"unicode/utf16"
|
|
|
|
"github.com/google/certificate-transparency-go/x509"
|
|
)
|
|
|
|
const (
|
|
// maxNameLen is the maximum accepted byte length for a name field.
|
|
// This value should be larger than any reasonable value.
|
|
maxNameLen = 2048
|
|
// maxDataLen is the maximum size in bytes of a variable data field.
|
|
// This value should be larger than any reasonable value.
|
|
maxDataLen = 1024 * 1024 // 1 Megabyte.
|
|
)
|
|
|
|
// GUIDs representing the contents of an UEFI_SIGNATURE_LIST.
|
|
var (
|
|
hashSHA256SigGUID = efiGUID{0xc1c41626, 0x504c, 0x4092, [8]byte{0xac, 0xa9, 0x41, 0xf9, 0x36, 0x93, 0x43, 0x28}}
|
|
hashSHA1SigGUID = efiGUID{0x826ca512, 0xcf10, 0x4ac9, [8]byte{0xb1, 0x87, 0xbe, 0x01, 0x49, 0x66, 0x31, 0xbd}}
|
|
hashSHA224SigGUID = efiGUID{0x0b6e5233, 0xa65c, 0x44c9, [8]byte{0x94, 0x07, 0xd9, 0xab, 0x83, 0xbf, 0xc8, 0xbd}}
|
|
hashSHA384SigGUID = efiGUID{0xff3e5307, 0x9fd0, 0x48c9, [8]byte{0x85, 0xf1, 0x8a, 0xd5, 0x6c, 0x70, 0x1e, 0x01}}
|
|
hashSHA512SigGUID = efiGUID{0x093e0fae, 0xa6c4, 0x4f50, [8]byte{0x9f, 0x1b, 0xd4, 0x1e, 0x2b, 0x89, 0xc1, 0x9a}}
|
|
keyRSA2048SigGUID = efiGUID{0x3c5766e8, 0x269c, 0x4e34, [8]byte{0xaa, 0x14, 0xed, 0x77, 0x6e, 0x85, 0xb3, 0xb6}}
|
|
certRSA2048SHA256SigGUID = efiGUID{0xe2b36190, 0x879b, 0x4a3d, [8]byte{0xad, 0x8d, 0xf2, 0xe7, 0xbb, 0xa3, 0x27, 0x84}}
|
|
certRSA2048SHA1SigGUID = efiGUID{0x67f8444f, 0x8743, 0x48f1, [8]byte{0xa3, 0x28, 0x1e, 0xaa, 0xb8, 0x73, 0x60, 0x80}}
|
|
certX509SigGUID = efiGUID{0xa5c059a1, 0x94e4, 0x4aa7, [8]byte{0x87, 0xb5, 0xab, 0x15, 0x5c, 0x2b, 0xf0, 0x72}}
|
|
certHashSHA256SigGUID = efiGUID{0x3bd2a492, 0x96c0, 0x4079, [8]byte{0xb4, 0x20, 0xfc, 0xf9, 0x8e, 0xf1, 0x03, 0xed}}
|
|
certHashSHA384SigGUID = efiGUID{0x7076876e, 0x80c2, 0x4ee6, [8]byte{0xaa, 0xd2, 0x28, 0xb3, 0x49, 0xa6, 0x86, 0x5b}}
|
|
certHashSHA512SigGUID = efiGUID{0x446dbf63, 0x2502, 0x4cda, [8]byte{0xbc, 0xfa, 0x24, 0x65, 0xd2, 0xb0, 0xfe, 0x9d}}
|
|
)
|
|
|
|
// EventType describes the type of event signalled in the event log.
|
|
type EventType uint32
|
|
|
|
// BIOS Events (TCG PC Client Specific Implementation Specification for Conventional BIOS 1.21)
|
|
const (
|
|
PrebootCert EventType = 0x00000000
|
|
PostCode EventType = 0x00000001
|
|
unused EventType = 0x00000002
|
|
NoAction EventType = 0x00000003
|
|
Separator EventType = 0x00000004
|
|
Action EventType = 0x00000005
|
|
EventTag EventType = 0x00000006
|
|
SCRTMContents EventType = 0x00000007
|
|
SCRTMVersion EventType = 0x00000008
|
|
CpuMicrocode EventType = 0x00000009
|
|
PlatformConfigFlags EventType = 0x0000000A
|
|
TableOfDevices EventType = 0x0000000B
|
|
CompactHash EventType = 0x0000000C
|
|
Ipl EventType = 0x0000000D
|
|
IplPartitionData EventType = 0x0000000E
|
|
NonhostCode EventType = 0x0000000F
|
|
NonhostConfig EventType = 0x00000010
|
|
NonhostInfo EventType = 0x00000011
|
|
OmitBootDeviceEvents EventType = 0x00000012
|
|
)
|
|
|
|
// EFI Events (TCG EFI Platform Specification Version 1.22)
|
|
const (
|
|
EFIEventBase EventType = 0x80000000
|
|
EFIVariableDriverConfig EventType = 0x80000001
|
|
EFIVariableBoot EventType = 0x80000002
|
|
EFIBootServicesApplication EventType = 0x80000003
|
|
EFIBootServicesDriver EventType = 0x80000004
|
|
EFIRuntimeServicesDriver EventType = 0x80000005
|
|
EFIGPTEvent EventType = 0x80000006
|
|
EFIAction EventType = 0x80000007
|
|
EFIPlatformFirmwareBlob EventType = 0x80000008
|
|
EFIHandoffTables EventType = 0x80000009
|
|
EFIHCRTMEvent EventType = 0x80000010
|
|
EFIVariableAuthority EventType = 0x800000e0
|
|
)
|
|
|
|
var eventTypeNames = map[EventType]string{
|
|
PrebootCert: "Preboot Cert",
|
|
PostCode: "POST Code",
|
|
unused: "Unused",
|
|
NoAction: "No Action",
|
|
Separator: "Separator",
|
|
Action: "Action",
|
|
EventTag: "Event Tag",
|
|
SCRTMContents: "S-CRTM Contents",
|
|
SCRTMVersion: "S-CRTM Version",
|
|
CpuMicrocode: "CPU Microcode",
|
|
PlatformConfigFlags: "Platform Config Flags",
|
|
TableOfDevices: "Table of Devices",
|
|
CompactHash: "Compact Hash",
|
|
Ipl: "IPL",
|
|
IplPartitionData: "IPL Partition Data",
|
|
NonhostCode: "Non-Host Code",
|
|
NonhostConfig: "Non-HostConfig",
|
|
NonhostInfo: "Non-Host Info",
|
|
OmitBootDeviceEvents: "Omit Boot Device Events",
|
|
|
|
EFIEventBase: "EFI Event Base",
|
|
EFIVariableDriverConfig: "EFI Variable Driver Config",
|
|
EFIVariableBoot: "EFI Variable Boot",
|
|
EFIBootServicesApplication: "EFI Boot Services Application",
|
|
EFIBootServicesDriver: "EFI Boot Services Driver",
|
|
EFIRuntimeServicesDriver: "EFI Runtime Services Driver",
|
|
EFIGPTEvent: "EFI GPT Event",
|
|
EFIAction: "EFI Action",
|
|
EFIPlatformFirmwareBlob: "EFI Platform Firmware Blob",
|
|
EFIVariableAuthority: "EFI Variable Authority",
|
|
EFIHandoffTables: "EFI Handoff Tables",
|
|
EFIHCRTMEvent: "EFI H-CRTM Event",
|
|
}
|
|
|
|
func (e EventType) String() string {
|
|
if s, ok := eventTypeNames[e]; ok {
|
|
return s
|
|
}
|
|
return fmt.Sprintf("EventType(0x%x)", uint32(e))
|
|
}
|
|
|
|
// UntrustedParseEventType returns the event type indicated by
|
|
// the provided value.
|
|
func UntrustedParseEventType(et uint32) (EventType, error) {
|
|
// "The value associated with a UEFI specific platform event type MUST be in
|
|
// the range between 0x80000000 and 0x800000FF, inclusive."
|
|
if (et < 0x80000000 && et > 0x800000FF) || (et < 0x0 && et > 0x12) {
|
|
return EventType(0), fmt.Errorf("event type not between [0x0, 0x12] or [0x80000000, 0x800000FF]: got %#x", et)
|
|
}
|
|
if _, ok := eventTypeNames[EventType(et)]; !ok {
|
|
return EventType(0), fmt.Errorf("unknown event type %#x", et)
|
|
}
|
|
return EventType(et), nil
|
|
}
|
|
|
|
// efiGUID represents the EFI_GUID type.
|
|
// See section "2.3.1 Data Types" in the specification for more information.
|
|
// type efiGUID [16]byte
|
|
type efiGUID struct {
|
|
Data1 uint32
|
|
Data2 uint16
|
|
Data3 uint16
|
|
Data4 [8]byte
|
|
}
|
|
|
|
func (d efiGUID) String() string {
|
|
var u [8]byte
|
|
binary.BigEndian.PutUint32(u[:4], d.Data1)
|
|
binary.BigEndian.PutUint16(u[4:6], d.Data2)
|
|
binary.BigEndian.PutUint16(u[6:8], d.Data3)
|
|
return fmt.Sprintf("%x-%x-%x-%x-%x", u[:4], u[4:6], u[6:8], d.Data4[:2], d.Data4[2:])
|
|
}
|
|
|
|
// UEFIVariableDataHeader represents the leading fixed-size fields
|
|
// within UEFI_VARIABLE_DATA.
|
|
type UEFIVariableDataHeader struct {
|
|
VariableName efiGUID
|
|
UnicodeNameLength uint64 // uintN
|
|
VariableDataLength uint64 // uintN
|
|
}
|
|
|
|
// UEFIVariableData represents the UEFI_VARIABLE_DATA structure.
|
|
type UEFIVariableData struct {
|
|
Header UEFIVariableDataHeader
|
|
UnicodeName []uint16
|
|
VariableData []byte // []int8
|
|
}
|
|
|
|
// ParseUEFIVariableData parses the data section of an event structured as
|
|
// a UEFI variable.
|
|
//
|
|
// https://trustedcomputinggroup.org/wp-content/uploads/TCG_PCClient_Specific_Platform_Profile_for_TPM_2p0_1p04_PUBLIC.pdf#page=100
|
|
func ParseUEFIVariableData(r io.Reader) (ret UEFIVariableData, err error) {
|
|
err = binary.Read(r, binary.LittleEndian, &ret.Header)
|
|
if err != nil {
|
|
return
|
|
}
|
|
if ret.Header.UnicodeNameLength > maxNameLen {
|
|
return UEFIVariableData{}, fmt.Errorf("unicode name too long: %d > %d", ret.Header.UnicodeNameLength, maxNameLen)
|
|
}
|
|
ret.UnicodeName = make([]uint16, ret.Header.UnicodeNameLength)
|
|
for i := 0; uint64(i) < ret.Header.UnicodeNameLength; i++ {
|
|
err = binary.Read(r, binary.LittleEndian, &ret.UnicodeName[i])
|
|
if err != nil {
|
|
return
|
|
}
|
|
}
|
|
if ret.Header.VariableDataLength > maxDataLen {
|
|
return UEFIVariableData{}, fmt.Errorf("variable data too long: %d > %d", ret.Header.VariableDataLength, maxDataLen)
|
|
}
|
|
ret.VariableData = make([]byte, ret.Header.VariableDataLength)
|
|
_, err = io.ReadFull(r, ret.VariableData)
|
|
return
|
|
}
|
|
|
|
func (v *UEFIVariableData) VarName() string {
|
|
return string(utf16.Decode(v.UnicodeName))
|
|
}
|
|
|
|
func (v *UEFIVariableData) SignatureData() (certs []x509.Certificate, hashes [][]byte, err error) {
|
|
return parseEfiSignatureList(v.VariableData)
|
|
}
|
|
|
|
// UEFIVariableAuthority describes the contents of a UEFI variable authority
|
|
// event.
|
|
type UEFIVariableAuthority struct {
|
|
Certs []x509.Certificate
|
|
}
|
|
|
|
// ParseUEFIVariableAuthority parses the data section of an event structured as
|
|
// a UEFI variable authority.
|
|
//
|
|
// https://uefi.org/sites/default/files/resources/UEFI_Spec_2_8_final.pdf#page=1789
|
|
func ParseUEFIVariableAuthority(r io.Reader) (UEFIVariableAuthority, error) {
|
|
v, err := ParseUEFIVariableData(r)
|
|
if err != nil {
|
|
return UEFIVariableAuthority{}, err
|
|
}
|
|
certs, err := parseEfiSignature(v.VariableData)
|
|
if err != nil {
|
|
return UEFIVariableAuthority{}, err
|
|
}
|
|
return UEFIVariableAuthority{Certs: certs}, nil
|
|
}
|
|
|
|
// efiSignatureData represents the EFI_SIGNATURE_DATA type.
|
|
// See section "31.4.1 Signature Database" in the specification for more information.
|
|
type efiSignatureData struct {
|
|
SignatureOwner efiGUID
|
|
SignatureData []byte // []int8
|
|
}
|
|
|
|
// efiSignatureList represents the EFI_SIGNATURE_LIST type.
|
|
// See section "31.4.1 Signature Database" in the specification for more information.
|
|
type efiSignatureListHeader struct {
|
|
SignatureType efiGUID
|
|
SignatureListSize uint32
|
|
SignatureHeaderSize uint32
|
|
SignatureSize uint32
|
|
}
|
|
|
|
type efiSignatureList struct {
|
|
Header efiSignatureListHeader
|
|
SignatureData []byte
|
|
Signatures []byte
|
|
}
|
|
|
|
// parseEfiSignatureList parses a EFI_SIGNATURE_LIST structure.
|
|
// The structure and related GUIDs are defined at:
|
|
// https://uefi.org/sites/default/files/resources/UEFI_Spec_2_8_final.pdf#page=1790
|
|
func parseEfiSignatureList(b []byte) ([]x509.Certificate, [][]byte, error) {
|
|
if len(b) < 28 {
|
|
// Being passed an empty signature list here appears to be valid
|
|
return nil, nil, nil
|
|
}
|
|
signatures := efiSignatureList{}
|
|
buf := bytes.NewReader(b)
|
|
certificates := []x509.Certificate{}
|
|
hashes := [][]byte{}
|
|
|
|
for buf.Len() > 0 {
|
|
err := binary.Read(buf, binary.LittleEndian, &signatures.Header)
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
|
|
if signatures.Header.SignatureHeaderSize > maxDataLen {
|
|
return nil, nil, fmt.Errorf("signature header too large: %d > %d", signatures.Header.SignatureHeaderSize, maxDataLen)
|
|
}
|
|
if signatures.Header.SignatureListSize > maxDataLen {
|
|
return nil, nil, fmt.Errorf("signature list too large: %d > %d", signatures.Header.SignatureListSize, maxDataLen)
|
|
}
|
|
|
|
signatureType := signatures.Header.SignatureType
|
|
switch signatureType {
|
|
case certX509SigGUID: // X509 certificate
|
|
for sigOffset := 0; uint32(sigOffset) < signatures.Header.SignatureListSize-28; {
|
|
signature := efiSignatureData{}
|
|
signature.SignatureData = make([]byte, signatures.Header.SignatureSize-16)
|
|
err := binary.Read(buf, binary.LittleEndian, &signature.SignatureOwner)
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
err = binary.Read(buf, binary.LittleEndian, &signature.SignatureData)
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
cert, err := x509.ParseCertificate(signature.SignatureData)
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
sigOffset += int(signatures.Header.SignatureSize)
|
|
certificates = append(certificates, *cert)
|
|
}
|
|
case hashSHA256SigGUID: // SHA256
|
|
for sigOffset := 0; uint32(sigOffset) < signatures.Header.SignatureListSize-28; {
|
|
signature := efiSignatureData{}
|
|
signature.SignatureData = make([]byte, signatures.Header.SignatureSize-16)
|
|
err := binary.Read(buf, binary.LittleEndian, &signature.SignatureOwner)
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
err = binary.Read(buf, binary.LittleEndian, &signature.SignatureData)
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
hashes = append(hashes, signature.SignatureData)
|
|
sigOffset += int(signatures.Header.SignatureSize)
|
|
}
|
|
case keyRSA2048SigGUID:
|
|
err = errors.New("unhandled RSA2048 key")
|
|
case certRSA2048SHA256SigGUID:
|
|
err = errors.New("unhandled RSA2048-SHA256 key")
|
|
case hashSHA1SigGUID:
|
|
err = errors.New("unhandled SHA1 hash")
|
|
case certRSA2048SHA1SigGUID:
|
|
err = errors.New("unhandled RSA2048-SHA1 key")
|
|
case hashSHA224SigGUID:
|
|
err = errors.New("unhandled SHA224 hash")
|
|
case hashSHA384SigGUID:
|
|
err = errors.New("unhandled SHA384 hash")
|
|
case hashSHA512SigGUID:
|
|
err = errors.New("unhandled SHA512 hash")
|
|
case certHashSHA256SigGUID:
|
|
err = errors.New("unhandled X509-SHA256 hash metadata")
|
|
case certHashSHA384SigGUID:
|
|
err = errors.New("unhandled X509-SHA384 hash metadata")
|
|
case certHashSHA512SigGUID:
|
|
err = errors.New("unhandled X509-SHA512 hash metadata")
|
|
default:
|
|
err = fmt.Errorf("unhandled signature type %s", signatureType)
|
|
}
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
}
|
|
return certificates, hashes, nil
|
|
}
|
|
|
|
// EFISignatureData represents the EFI_SIGNATURE_DATA type.
|
|
// See section "31.4.1 Signature Database" in the specification
|
|
// for more information.
|
|
type EFISignatureData struct {
|
|
SignatureOwner efiGUID
|
|
SignatureData []byte // []int8
|
|
}
|
|
|
|
func parseEfiSignature(b []byte) ([]x509.Certificate, error) {
|
|
certificates := []x509.Certificate{}
|
|
|
|
if len(b) < 16 {
|
|
return nil, fmt.Errorf("invalid signature: buffer smaller than header (%d < %d)", len(b), 16)
|
|
}
|
|
|
|
buf := bytes.NewReader(b)
|
|
signature := EFISignatureData{}
|
|
signature.SignatureData = make([]byte, len(b)-16)
|
|
|
|
if err := binary.Read(buf, binary.LittleEndian, &signature.SignatureOwner); err != nil {
|
|
return certificates, err
|
|
}
|
|
if err := binary.Read(buf, binary.LittleEndian, &signature.SignatureData); err != nil {
|
|
return certificates, err
|
|
}
|
|
cert, err := x509.ParseCertificate(signature.SignatureData)
|
|
if err == nil {
|
|
certificates = append(certificates, *cert)
|
|
}
|
|
return certificates, err
|
|
}
|