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Merge pull request #144 from mjg59/use_header_digest_size

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Pay attention to digest size information in the headers
This commit is contained in:
Eric Chiang 2019-12-10 12:33:31 -08:00 committed by GitHub
commit 6884946fc9
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 28 additions and 18 deletions
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37
attest/eventlog.go
View File

@ -343,20 +343,21 @@ const eventTypeNoAction = 0x03
// ParseEventLog parses an unverified measurement log.
func ParseEventLog(measurementLog []byte) (*EventLog, error) {
var specID *specIDEvent
r := bytes.NewBuffer(measurementLog)
parseFn := parseRawEvent
var el EventLog
e, err := parseFn(r)
e, err := parseFn(r, specID)
if err != nil {
return nil, fmt.Errorf("parse first event: %v", err)
}
if e.typ == eventTypeNoAction {
specID, err := parseSpecIDEvent(e.data)
specID, err = parseSpecIDEvent(e.data)
if err != nil {
return nil, fmt.Errorf("failed to parse spec ID event: %v", err)
}
for _, alg := range specID.algs {
switch tpm2.Algorithm(alg) {
switch tpm2.Algorithm(alg.ID) {
case tpm2.AlgSHA1:
el.Algs = append(el.Algs, HashSHA1)
case tpm2.AlgSHA256:
@ -378,7 +379,7 @@ func ParseEventLog(measurementLog []byte) (*EventLog, error) {
}
sequence := 1
for r.Len() != 0 {
e, err := parseFn(r)
e, err := parseFn(r, specID)
if err != nil {
return nil, err
}
@ -390,7 +391,7 @@ func ParseEventLog(measurementLog []byte) (*EventLog, error) {
}
type specIDEvent struct {
algs []uint16
algs []specAlgSize
}
type specAlgSize struct {
@ -450,7 +451,7 @@ func parseSpecIDEvent(b []byte) (*specIDEvent, error) {
if err := binary.Read(r, binary.LittleEndian, &specAlg); err != nil {
return nil, fmt.Errorf("reading algorithm: %v", err)
}
e.algs = append(e.algs, specAlg.ID)
e.algs = append(e.algs, specAlg)
}
var vendorInfoSize uint8
@ -489,7 +490,7 @@ func (e *eventSizeErr) Error() string {
return fmt.Sprintf("event data size (%d bytes) is greater than remaining measurement log (%d bytes)", e.eventSize, e.logSize)
}
func parseRawEvent(r *bytes.Buffer) (event rawEvent, err error) {
func parseRawEvent(r *bytes.Buffer, specID *specIDEvent) (event rawEvent, err error) {
var h rawEventHeader
if err = binary.Read(r, binary.LittleEndian, &h); err != nil {
return event, err
@ -516,7 +517,7 @@ type rawEvent2Header struct {
Type uint32
}
func parseRawEvent2(r *bytes.Buffer) (event rawEvent, err error) {
func parseRawEvent2(r *bytes.Buffer, specID *specIDEvent) (event rawEvent, err error) {
var h rawEvent2Header
if err = binary.Read(r, binary.LittleEndian, &h); err != nil {
return event, err
@ -529,20 +530,24 @@ func parseRawEvent2(r *bytes.Buffer) (event rawEvent, err error) {
if err := binary.Read(r, binary.LittleEndian, &numDigests); err != nil {
return event, err
}
for i := 0; i < int(numDigests); i++ {
var algID uint16
if err := binary.Read(r, binary.LittleEndian, &algID); err != nil {
return event, err
}
var digest []byte
switch algID {
case algSHA1:
digest = make([]byte, crypto.SHA1.Size())
case algSHA256:
digest = make([]byte, crypto.SHA256.Size())
default:
// ignore signatures that aren't SHA1 or SHA256
continue
for _, alg := range specID.algs {
if alg.ID != algID {
continue
}
if uint16(r.Len()) < alg.Size {
return event, fmt.Errorf("reading digest: %v", io.ErrUnexpectedEOF)
}
digest = make([]byte, alg.Size)
}
if len(digest) == 0 {
return event, fmt.Errorf("unknown algorithm ID %x", algID)
}
if _, err := io.ReadFull(r, digest); err != nil {
return event, err

9
attest/eventlog_test.go
View File

@ -232,13 +232,14 @@ func TestParseSpecIDEvent(t *testing.T) {
for _, test := range tests {
t.Run(test.name, func(t *testing.T) {
spec, err := parseSpecIDEvent(test.data)
var algs []uint16
if (err != nil) != test.wantErr {
t.Fatalf("parsing spec, wantErr=%t, got=%v", test.wantErr, err)
}
if err != nil {
return
}
algsEq := func(got, want []uint16) bool {
algsEq := func(want, got []uint16) bool {
if len(got) != len(want) {
return false
}
@ -250,7 +251,11 @@ func TestParseSpecIDEvent(t *testing.T) {
return true
}
if !algsEq(test.want, spec.algs) {
for _, alg := range(spec.algs) {
algs = append(algs, alg.ID)
}
if !algsEq(test.want, algs) {
t.Errorf("algorithms, got=%x, want=%x", spec.algs, test.want)
}
})