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package krl
import (
"crypto/sha1"
"fmt"
"golang.org/x/crypto/ssh"
)
// Hundreds of millions, or 32MB of bitmap
const krlMaxBitmapSize = 0x10000000
// KRLSigningErrors is a slice of error messages which correspond one-to-one
// with KRL.SigningKeys.
type KRLSigningErrors []error
func (k KRLSigningErrors) Error() string {
return fmt.Sprintf("krl: bad signatures: %v", []error(k))
}
func (k KRLSigningErrors) err() error {
for _, err := range k {
if err != nil {
return k
}
}
return nil
}
// ParseKRL parses a KRL. If the KRL was signed by one or more authorities,
// those signatures will be checked, and any verification errors will be
// returned.
func ParseKRL(in []byte) (*KRL, error) {
orig := in
var header krlHeader
if err := ssh.Unmarshal(in, &header); err != nil {
return nil, fmt.Errorf("krl: while parsing header: %v", err)
}
if header.KRLMagic != krlMagic {
return nil, fmt.Errorf("krl: bad magic value %x", header.KRLMagic)
}
if header.KRLFormatVersion != 1 {
return nil, fmt.Errorf("krl: bad format version %v", header.KRLFormatVersion)
}
krl := &KRL{
Version: header.KRLVersion,
GeneratedDate: header.GeneratedDate,
Comment: header.Comment,
}
in = header.Rest
for len(in) > 0 && in[0] != 4 { // // KRL_SECTION_SIGNATURE
var sdata krlSection
if err := ssh.Unmarshal(in, &sdata); err != nil {
return nil, fmt.Errorf("krl: malformed section: %v", err)
}
in = sdata.Rest
var err error
var section KRLSection
switch sdata.SectionType {
case 1: // KRL_SECTION_CERTIFICATES
section, err = parseCertificateSection(sdata.SectionData)
case 2: // KRL_SECTION_EXPLICIT_KEY
section, err = parseExplicitKeySection(sdata.SectionData)
case 3: // KRL_SECTION_FINGERPRINT_SHA1
section, err = parseFingerprintSection(sdata.SectionData)
default:
return nil, fmt.Errorf("krl: unexpected section type %d", sdata.SectionType)
}
if err != nil {
return nil, err
}
krl.Sections = append(krl.Sections, section)
}
var signingErrors KRLSigningErrors
for len(in) > 0 {
var sigHeader krlSignatureHeader
if err := ssh.Unmarshal(in, &sigHeader); err != nil {
return nil, fmt.Errorf("krl: malfored signature header: %v", err)
}
in = sigHeader.Rest
key, err := ssh.ParsePublicKey(sigHeader.SignatureKey)
if err != nil {
return nil, fmt.Errorf("krl: malformed signing key: %v", err)
}
var sig krlSignature
if err := ssh.Unmarshal(in, &sig); err != nil {
return nil, fmt.Errorf("krl: malfored signature wrapper: %v", err)
}
in = sig.Rest
sshsig := new(ssh.Signature)
if err := ssh.Unmarshal(sig.Signature, sshsig); err != nil {
return nil, fmt.Errorf("krl: malformed signature: %v", err)
}
// The entire KRL up until immediately after the signature
// header is signed.
data := orig[:len(orig)-len(sigHeader.Rest)]
krl.SigningKeys = append(krl.SigningKeys, key)
signingErrors = append(signingErrors, key.Verify(data, sshsig))
}
return krl, signingErrors.err()
}
func parseCertificateSection(in []byte) (*KRLCertificateSection, error) {
var header krlCertificateSectionHeader
if err := ssh.Unmarshal(in, &header); err != nil {
return nil, fmt.Errorf("krl: while parsing certificate section header: %v", err)
}
ca, err := ssh.ParsePublicKey(header.CAKey)
if err != nil {
return nil, fmt.Errorf("krl: while parsing CA key: %v", err)
}
k := &KRLCertificateSection{CA: ca}
in = header.Rest
for len(in) > 0 {
var section krlCertificateSection
if err := ssh.Unmarshal(in, §ion); err != nil {
return nil, fmt.Errorf("krl: malformed certificate section: %v", err)
}
in = section.Rest
var err error
var subsection KRLCertificateSubsection
switch section.CertSectionType {
case krlSectionCertSerialList:
subsection, err = parseCertSerialList(section.CertSectionData)
case krlSectionCertSerialRange:
subsection, err = parseCertSerialRange(section.CertSectionData)
case krlSectionCertSerialBitmap:
subsection, err = parseCertSerialBitmap(section.CertSectionData)
case krlSectionCertKeyId:
subsection, err = parseCertKeyID(section.CertSectionData)
default:
return nil, fmt.Errorf("krl: unexpected cert section type %x", in[0])
}
if err != nil {
return nil, err
}
k.Sections = append(k.Sections, subsection)
}
return k, nil
}
func parseCertSerialList(in []byte) (*KRLCertificateSerialList, error) {
s := &KRLCertificateSerialList{}
for len(in) > 0 {
var list krlSerialList
if err := ssh.Unmarshal(in, &list); err != nil {
return nil, fmt.Errorf("krl: while parsing serial in list: %v", err)
}
in = list.Rest
*s = append(*s, list.RevokedCertSerial)
}
return s, nil
}
func parseCertSerialRange(in []byte) (*KRLCertificateSerialRange, error) {
var s krlSerialRange
if err := ssh.Unmarshal(in, &s); err != nil {
return nil, fmt.Errorf("krl: while parsing serial range: %v", err)
}
return &KRLCertificateSerialRange{
Min: s.SerialMin,
Max: s.SerialMax,
}, nil
}
func parseCertSerialBitmap(in []byte) (*KRLCertificateSerialBitmap, error) {
var s krlSerialBitmap
if err := ssh.Unmarshal(in, &s); err != nil {
return nil, fmt.Errorf("krl: while parsing serial bitmap: %v", err)
}
if bl := s.RevokedKeysBitmap.BitLen(); bl > krlMaxBitmapSize {
return nil, fmt.Errorf("krl: serial bitmap too wide: %v", bl)
}
return &KRLCertificateSerialBitmap{
Offset: s.SerialOffset,
Bitmap: s.RevokedKeysBitmap,
}, nil
}
func parseCertKeyID(in []byte) (*KRLCertificateKeyID, error) {
s := &KRLCertificateKeyID{}
for len(in) > 0 {
var list krlKeyID
if err := ssh.Unmarshal(in, &list); err != nil {
return nil, fmt.Errorf("krl: while parsing key id in list: %v", err)
}
in = list.Rest
*s = append(*s, list.KeyID)
}
return s, nil
}
func parseExplicitKeySection(in []byte) (*KRLExplicitKeySection, error) {
s := &KRLExplicitKeySection{}
for len(in) > 0 {
var list krlExplicitKey
if err := ssh.Unmarshal(in, &list); err != nil {
return nil, fmt.Errorf("krl: while parsing explicit key in list: %v", err)
}
in = list.Rest
key, err := ssh.ParsePublicKey(list.PublicKeyBlob)
if err != nil {
return nil, fmt.Errorf("krl: while parsing explicit key: %v", err)
}
*s = append(*s, key)
}
return s, nil
}
func parseFingerprintSection(in []byte) (*KRLFingerprintSection, error) {
s := &KRLFingerprintSection{}
for len(in) > 0 {
var list krlFingerprintSHA1
if err := ssh.Unmarshal(in, &list); err != nil {
return nil, fmt.Errorf("krl: while parsing fingerprint in list: %v", err)
}
in = list.Rest
if len(list.PublicKeyHash) != sha1.Size {
return nil, fmt.Errorf("krl: key fingerprint wrong length for SHA1: %x", list.PublicKeyHash)
}
var sha [sha1.Size]byte
copy(sha[:], list.PublicKeyHash)
*s = append(*s, sha)
}
return s, nil
}
|
