distribution/vendor/github.com/miekg/dns/dnssec.go
Derek McGowan a685e3fc98
Replace godep with vndr
Vndr has a simpler configuration and allows pointing to forked
packages. Additionally other docker projects are now using
vndr making vendoring in distribution more consistent.

Updates letsencrypt to use fork.
No longer uses sub-vendored packages.

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)
2016-11-23 15:07:06 -08:00

722 lines
18 KiB
Go

package dns
import (
"bytes"
"crypto"
"crypto/dsa"
"crypto/ecdsa"
"crypto/elliptic"
_ "crypto/md5"
"crypto/rand"
"crypto/rsa"
_ "crypto/sha1"
_ "crypto/sha256"
_ "crypto/sha512"
"encoding/asn1"
"encoding/binary"
"encoding/hex"
"math/big"
"sort"
"strings"
"time"
)
// DNSSEC encryption algorithm codes.
const (
_ uint8 = iota
RSAMD5
DH
DSA
_ // Skip 4, RFC 6725, section 2.1
RSASHA1
DSANSEC3SHA1
RSASHA1NSEC3SHA1
RSASHA256
_ // Skip 9, RFC 6725, section 2.1
RSASHA512
_ // Skip 11, RFC 6725, section 2.1
ECCGOST
ECDSAP256SHA256
ECDSAP384SHA384
INDIRECT uint8 = 252
PRIVATEDNS uint8 = 253 // Private (experimental keys)
PRIVATEOID uint8 = 254
)
// Map for algorithm names.
var AlgorithmToString = map[uint8]string{
RSAMD5: "RSAMD5",
DH: "DH",
DSA: "DSA",
RSASHA1: "RSASHA1",
DSANSEC3SHA1: "DSA-NSEC3-SHA1",
RSASHA1NSEC3SHA1: "RSASHA1-NSEC3-SHA1",
RSASHA256: "RSASHA256",
RSASHA512: "RSASHA512",
ECCGOST: "ECC-GOST",
ECDSAP256SHA256: "ECDSAP256SHA256",
ECDSAP384SHA384: "ECDSAP384SHA384",
INDIRECT: "INDIRECT",
PRIVATEDNS: "PRIVATEDNS",
PRIVATEOID: "PRIVATEOID",
}
// Map of algorithm strings.
var StringToAlgorithm = reverseInt8(AlgorithmToString)
// Map of algorithm crypto hashes.
var AlgorithmToHash = map[uint8]crypto.Hash{
RSAMD5: crypto.MD5, // Deprecated in RFC 6725
RSASHA1: crypto.SHA1,
RSASHA1NSEC3SHA1: crypto.SHA1,
RSASHA256: crypto.SHA256,
ECDSAP256SHA256: crypto.SHA256,
ECDSAP384SHA384: crypto.SHA384,
RSASHA512: crypto.SHA512,
}
// DNSSEC hashing algorithm codes.
const (
_ uint8 = iota
SHA1 // RFC 4034
SHA256 // RFC 4509
GOST94 // RFC 5933
SHA384 // Experimental
SHA512 // Experimental
)
// Map for hash names.
var HashToString = map[uint8]string{
SHA1: "SHA1",
SHA256: "SHA256",
GOST94: "GOST94",
SHA384: "SHA384",
SHA512: "SHA512",
}
// Map of hash strings.
var StringToHash = reverseInt8(HashToString)
// DNSKEY flag values.
const (
SEP = 1
REVOKE = 1 << 7
ZONE = 1 << 8
)
// The RRSIG needs to be converted to wireformat with some of the rdata (the signature) missing.
type rrsigWireFmt struct {
TypeCovered uint16
Algorithm uint8
Labels uint8
OrigTtl uint32
Expiration uint32
Inception uint32
KeyTag uint16
SignerName string `dns:"domain-name"`
/* No Signature */
}
// Used for converting DNSKEY's rdata to wirefmt.
type dnskeyWireFmt struct {
Flags uint16
Protocol uint8
Algorithm uint8
PublicKey string `dns:"base64"`
/* Nothing is left out */
}
func divRoundUp(a, b int) int {
return (a + b - 1) / b
}
// KeyTag calculates the keytag (or key-id) of the DNSKEY.
func (k *DNSKEY) KeyTag() uint16 {
if k == nil {
return 0
}
var keytag int
switch k.Algorithm {
case RSAMD5:
// Look at the bottom two bytes of the modules, which the last
// item in the pubkey. We could do this faster by looking directly
// at the base64 values. But I'm lazy.
modulus, _ := fromBase64([]byte(k.PublicKey))
if len(modulus) > 1 {
x := binary.BigEndian.Uint16(modulus[len(modulus)-2:])
keytag = int(x)
}
default:
keywire := new(dnskeyWireFmt)
keywire.Flags = k.Flags
keywire.Protocol = k.Protocol
keywire.Algorithm = k.Algorithm
keywire.PublicKey = k.PublicKey
wire := make([]byte, DefaultMsgSize)
n, err := packKeyWire(keywire, wire)
if err != nil {
return 0
}
wire = wire[:n]
for i, v := range wire {
if i&1 != 0 {
keytag += int(v) // must be larger than uint32
} else {
keytag += int(v) << 8
}
}
keytag += (keytag >> 16) & 0xFFFF
keytag &= 0xFFFF
}
return uint16(keytag)
}
// ToDS converts a DNSKEY record to a DS record.
func (k *DNSKEY) ToDS(h uint8) *DS {
if k == nil {
return nil
}
ds := new(DS)
ds.Hdr.Name = k.Hdr.Name
ds.Hdr.Class = k.Hdr.Class
ds.Hdr.Rrtype = TypeDS
ds.Hdr.Ttl = k.Hdr.Ttl
ds.Algorithm = k.Algorithm
ds.DigestType = h
ds.KeyTag = k.KeyTag()
keywire := new(dnskeyWireFmt)
keywire.Flags = k.Flags
keywire.Protocol = k.Protocol
keywire.Algorithm = k.Algorithm
keywire.PublicKey = k.PublicKey
wire := make([]byte, DefaultMsgSize)
n, err := packKeyWire(keywire, wire)
if err != nil {
return nil
}
wire = wire[:n]
owner := make([]byte, 255)
off, err1 := PackDomainName(strings.ToLower(k.Hdr.Name), owner, 0, nil, false)
if err1 != nil {
return nil
}
owner = owner[:off]
// RFC4034:
// digest = digest_algorithm( DNSKEY owner name | DNSKEY RDATA);
// "|" denotes concatenation
// DNSKEY RDATA = Flags | Protocol | Algorithm | Public Key.
// digest buffer
digest := append(owner, wire...) // another copy
var hash crypto.Hash
switch h {
case SHA1:
hash = crypto.SHA1
case SHA256:
hash = crypto.SHA256
case SHA384:
hash = crypto.SHA384
case SHA512:
hash = crypto.SHA512
default:
return nil
}
s := hash.New()
s.Write(digest)
ds.Digest = hex.EncodeToString(s.Sum(nil))
return ds
}
// ToCDNSKEY converts a DNSKEY record to a CDNSKEY record.
func (k *DNSKEY) ToCDNSKEY() *CDNSKEY {
c := &CDNSKEY{DNSKEY: *k}
c.Hdr = *k.Hdr.copyHeader()
c.Hdr.Rrtype = TypeCDNSKEY
return c
}
// ToCDS converts a DS record to a CDS record.
func (d *DS) ToCDS() *CDS {
c := &CDS{DS: *d}
c.Hdr = *d.Hdr.copyHeader()
c.Hdr.Rrtype = TypeCDS
return c
}
// Sign signs an RRSet. The signature needs to be filled in with the values:
// Inception, Expiration, KeyTag, SignerName and Algorithm. The rest is copied
// from the RRset. Sign returns a non-nill error when the signing went OK.
// There is no check if RRSet is a proper (RFC 2181) RRSet. If OrigTTL is non
// zero, it is used as-is, otherwise the TTL of the RRset is used as the
// OrigTTL.
func (rr *RRSIG) Sign(k crypto.Signer, rrset []RR) error {
if k == nil {
return ErrPrivKey
}
// s.Inception and s.Expiration may be 0 (rollover etc.), the rest must be set
if rr.KeyTag == 0 || len(rr.SignerName) == 0 || rr.Algorithm == 0 {
return ErrKey
}
rr.Hdr.Rrtype = TypeRRSIG
rr.Hdr.Name = rrset[0].Header().Name
rr.Hdr.Class = rrset[0].Header().Class
if rr.OrigTtl == 0 { // If set don't override
rr.OrigTtl = rrset[0].Header().Ttl
}
rr.TypeCovered = rrset[0].Header().Rrtype
rr.Labels = uint8(CountLabel(rrset[0].Header().Name))
if strings.HasPrefix(rrset[0].Header().Name, "*") {
rr.Labels-- // wildcard, remove from label count
}
sigwire := new(rrsigWireFmt)
sigwire.TypeCovered = rr.TypeCovered
sigwire.Algorithm = rr.Algorithm
sigwire.Labels = rr.Labels
sigwire.OrigTtl = rr.OrigTtl
sigwire.Expiration = rr.Expiration
sigwire.Inception = rr.Inception
sigwire.KeyTag = rr.KeyTag
// For signing, lowercase this name
sigwire.SignerName = strings.ToLower(rr.SignerName)
// Create the desired binary blob
signdata := make([]byte, DefaultMsgSize)
n, err := packSigWire(sigwire, signdata)
if err != nil {
return err
}
signdata = signdata[:n]
wire, err := rawSignatureData(rrset, rr)
if err != nil {
return err
}
signdata = append(signdata, wire...)
hash, ok := AlgorithmToHash[rr.Algorithm]
if !ok {
return ErrAlg
}
h := hash.New()
h.Write(signdata)
signature, err := sign(k, h.Sum(nil), hash, rr.Algorithm)
if err != nil {
return err
}
rr.Signature = toBase64(signature)
return nil
}
func sign(k crypto.Signer, hashed []byte, hash crypto.Hash, alg uint8) ([]byte, error) {
signature, err := k.Sign(rand.Reader, hashed, hash)
if err != nil {
return nil, err
}
switch alg {
case RSASHA1, RSASHA1NSEC3SHA1, RSASHA256, RSASHA512:
return signature, nil
case ECDSAP256SHA256, ECDSAP384SHA384:
ecdsaSignature := &struct {
R, S *big.Int
}{}
if _, err := asn1.Unmarshal(signature, ecdsaSignature); err != nil {
return nil, err
}
var intlen int
switch alg {
case ECDSAP256SHA256:
intlen = 32
case ECDSAP384SHA384:
intlen = 48
}
signature := intToBytes(ecdsaSignature.R, intlen)
signature = append(signature, intToBytes(ecdsaSignature.S, intlen)...)
return signature, nil
// There is no defined interface for what a DSA backed crypto.Signer returns
case DSA, DSANSEC3SHA1:
// t := divRoundUp(divRoundUp(p.PublicKey.Y.BitLen(), 8)-64, 8)
// signature := []byte{byte(t)}
// signature = append(signature, intToBytes(r1, 20)...)
// signature = append(signature, intToBytes(s1, 20)...)
// rr.Signature = signature
}
return nil, ErrAlg
}
// Verify validates an RRSet with the signature and key. This is only the
// cryptographic test, the signature validity period must be checked separately.
// This function copies the rdata of some RRs (to lowercase domain names) for the validation to work.
func (rr *RRSIG) Verify(k *DNSKEY, rrset []RR) error {
// First the easy checks
if !IsRRset(rrset) {
return ErrRRset
}
if rr.KeyTag != k.KeyTag() {
return ErrKey
}
if rr.Hdr.Class != k.Hdr.Class {
return ErrKey
}
if rr.Algorithm != k.Algorithm {
return ErrKey
}
if strings.ToLower(rr.SignerName) != strings.ToLower(k.Hdr.Name) {
return ErrKey
}
if k.Protocol != 3 {
return ErrKey
}
// IsRRset checked that we have at least one RR and that the RRs in
// the set have consistent type, class, and name. Also check that type and
// class matches the RRSIG record.
if rrset[0].Header().Class != rr.Hdr.Class {
return ErrRRset
}
if rrset[0].Header().Rrtype != rr.TypeCovered {
return ErrRRset
}
// RFC 4035 5.3.2. Reconstructing the Signed Data
// Copy the sig, except the rrsig data
sigwire := new(rrsigWireFmt)
sigwire.TypeCovered = rr.TypeCovered
sigwire.Algorithm = rr.Algorithm
sigwire.Labels = rr.Labels
sigwire.OrigTtl = rr.OrigTtl
sigwire.Expiration = rr.Expiration
sigwire.Inception = rr.Inception
sigwire.KeyTag = rr.KeyTag
sigwire.SignerName = strings.ToLower(rr.SignerName)
// Create the desired binary blob
signeddata := make([]byte, DefaultMsgSize)
n, err := packSigWire(sigwire, signeddata)
if err != nil {
return err
}
signeddata = signeddata[:n]
wire, err := rawSignatureData(rrset, rr)
if err != nil {
return err
}
signeddata = append(signeddata, wire...)
sigbuf := rr.sigBuf() // Get the binary signature data
if rr.Algorithm == PRIVATEDNS { // PRIVATEOID
// TODO(miek)
// remove the domain name and assume its ours?
}
hash, ok := AlgorithmToHash[rr.Algorithm]
if !ok {
return ErrAlg
}
switch rr.Algorithm {
case RSASHA1, RSASHA1NSEC3SHA1, RSASHA256, RSASHA512, RSAMD5:
// TODO(mg): this can be done quicker, ie. cache the pubkey data somewhere??
pubkey := k.publicKeyRSA() // Get the key
if pubkey == nil {
return ErrKey
}
h := hash.New()
h.Write(signeddata)
return rsa.VerifyPKCS1v15(pubkey, hash, h.Sum(nil), sigbuf)
case ECDSAP256SHA256, ECDSAP384SHA384:
pubkey := k.publicKeyECDSA()
if pubkey == nil {
return ErrKey
}
// Split sigbuf into the r and s coordinates
r := new(big.Int).SetBytes(sigbuf[:len(sigbuf)/2])
s := new(big.Int).SetBytes(sigbuf[len(sigbuf)/2:])
h := hash.New()
h.Write(signeddata)
if ecdsa.Verify(pubkey, h.Sum(nil), r, s) {
return nil
}
return ErrSig
default:
return ErrAlg
}
}
// ValidityPeriod uses RFC1982 serial arithmetic to calculate
// if a signature period is valid. If t is the zero time, the
// current time is taken other t is. Returns true if the signature
// is valid at the given time, otherwise returns false.
func (rr *RRSIG) ValidityPeriod(t time.Time) bool {
var utc int64
if t.IsZero() {
utc = time.Now().UTC().Unix()
} else {
utc = t.UTC().Unix()
}
modi := (int64(rr.Inception) - utc) / year68
mode := (int64(rr.Expiration) - utc) / year68
ti := int64(rr.Inception) + (modi * year68)
te := int64(rr.Expiration) + (mode * year68)
return ti <= utc && utc <= te
}
// Return the signatures base64 encodedig sigdata as a byte slice.
func (rr *RRSIG) sigBuf() []byte {
sigbuf, err := fromBase64([]byte(rr.Signature))
if err != nil {
return nil
}
return sigbuf
}
// publicKeyRSA returns the RSA public key from a DNSKEY record.
func (k *DNSKEY) publicKeyRSA() *rsa.PublicKey {
keybuf, err := fromBase64([]byte(k.PublicKey))
if err != nil {
return nil
}
// RFC 2537/3110, section 2. RSA Public KEY Resource Records
// Length is in the 0th byte, unless its zero, then it
// it in bytes 1 and 2 and its a 16 bit number
explen := uint16(keybuf[0])
keyoff := 1
if explen == 0 {
explen = uint16(keybuf[1])<<8 | uint16(keybuf[2])
keyoff = 3
}
pubkey := new(rsa.PublicKey)
pubkey.N = big.NewInt(0)
shift := uint64((explen - 1) * 8)
expo := uint64(0)
for i := int(explen - 1); i > 0; i-- {
expo += uint64(keybuf[keyoff+i]) << shift
shift -= 8
}
// Remainder
expo += uint64(keybuf[keyoff])
if expo > 2<<31 {
// Larger expo than supported.
// println("dns: F5 primes (or larger) are not supported")
return nil
}
pubkey.E = int(expo)
pubkey.N.SetBytes(keybuf[keyoff+int(explen):])
return pubkey
}
// publicKeyECDSA returns the Curve public key from the DNSKEY record.
func (k *DNSKEY) publicKeyECDSA() *ecdsa.PublicKey {
keybuf, err := fromBase64([]byte(k.PublicKey))
if err != nil {
return nil
}
pubkey := new(ecdsa.PublicKey)
switch k.Algorithm {
case ECDSAP256SHA256:
pubkey.Curve = elliptic.P256()
if len(keybuf) != 64 {
// wrongly encoded key
return nil
}
case ECDSAP384SHA384:
pubkey.Curve = elliptic.P384()
if len(keybuf) != 96 {
// Wrongly encoded key
return nil
}
}
pubkey.X = big.NewInt(0)
pubkey.X.SetBytes(keybuf[:len(keybuf)/2])
pubkey.Y = big.NewInt(0)
pubkey.Y.SetBytes(keybuf[len(keybuf)/2:])
return pubkey
}
func (k *DNSKEY) publicKeyDSA() *dsa.PublicKey {
keybuf, err := fromBase64([]byte(k.PublicKey))
if err != nil {
return nil
}
if len(keybuf) < 22 {
return nil
}
t, keybuf := int(keybuf[0]), keybuf[1:]
size := 64 + t*8
q, keybuf := keybuf[:20], keybuf[20:]
if len(keybuf) != 3*size {
return nil
}
p, keybuf := keybuf[:size], keybuf[size:]
g, y := keybuf[:size], keybuf[size:]
pubkey := new(dsa.PublicKey)
pubkey.Parameters.Q = big.NewInt(0).SetBytes(q)
pubkey.Parameters.P = big.NewInt(0).SetBytes(p)
pubkey.Parameters.G = big.NewInt(0).SetBytes(g)
pubkey.Y = big.NewInt(0).SetBytes(y)
return pubkey
}
type wireSlice [][]byte
func (p wireSlice) Len() int { return len(p) }
func (p wireSlice) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
func (p wireSlice) Less(i, j int) bool {
_, ioff, _ := UnpackDomainName(p[i], 0)
_, joff, _ := UnpackDomainName(p[j], 0)
return bytes.Compare(p[i][ioff+10:], p[j][joff+10:]) < 0
}
// Return the raw signature data.
func rawSignatureData(rrset []RR, s *RRSIG) (buf []byte, err error) {
wires := make(wireSlice, len(rrset))
for i, r := range rrset {
r1 := r.copy()
r1.Header().Ttl = s.OrigTtl
labels := SplitDomainName(r1.Header().Name)
// 6.2. Canonical RR Form. (4) - wildcards
if len(labels) > int(s.Labels) {
// Wildcard
r1.Header().Name = "*." + strings.Join(labels[len(labels)-int(s.Labels):], ".") + "."
}
// RFC 4034: 6.2. Canonical RR Form. (2) - domain name to lowercase
r1.Header().Name = strings.ToLower(r1.Header().Name)
// 6.2. Canonical RR Form. (3) - domain rdata to lowercase.
// NS, MD, MF, CNAME, SOA, MB, MG, MR, PTR,
// HINFO, MINFO, MX, RP, AFSDB, RT, SIG, PX, NXT, NAPTR, KX,
// SRV, DNAME, A6
//
// RFC 6840 - Clarifications and Implementation Notes for DNS Security (DNSSEC):
// Section 6.2 of [RFC4034] also erroneously lists HINFO as a record
// that needs conversion to lowercase, and twice at that. Since HINFO
// records contain no domain names, they are not subject to case
// conversion.
switch x := r1.(type) {
case *NS:
x.Ns = strings.ToLower(x.Ns)
case *CNAME:
x.Target = strings.ToLower(x.Target)
case *SOA:
x.Ns = strings.ToLower(x.Ns)
x.Mbox = strings.ToLower(x.Mbox)
case *MB:
x.Mb = strings.ToLower(x.Mb)
case *MG:
x.Mg = strings.ToLower(x.Mg)
case *MR:
x.Mr = strings.ToLower(x.Mr)
case *PTR:
x.Ptr = strings.ToLower(x.Ptr)
case *MINFO:
x.Rmail = strings.ToLower(x.Rmail)
x.Email = strings.ToLower(x.Email)
case *MX:
x.Mx = strings.ToLower(x.Mx)
case *NAPTR:
x.Replacement = strings.ToLower(x.Replacement)
case *KX:
x.Exchanger = strings.ToLower(x.Exchanger)
case *SRV:
x.Target = strings.ToLower(x.Target)
case *DNAME:
x.Target = strings.ToLower(x.Target)
}
// 6.2. Canonical RR Form. (5) - origTTL
wire := make([]byte, r1.len()+1) // +1 to be safe(r)
off, err1 := PackRR(r1, wire, 0, nil, false)
if err1 != nil {
return nil, err1
}
wire = wire[:off]
wires[i] = wire
}
sort.Sort(wires)
for i, wire := range wires {
if i > 0 && bytes.Equal(wire, wires[i-1]) {
continue
}
buf = append(buf, wire...)
}
return buf, nil
}
func packSigWire(sw *rrsigWireFmt, msg []byte) (int, error) {
// copied from zmsg.go RRSIG packing
off, err := packUint16(sw.TypeCovered, msg, 0)
if err != nil {
return off, err
}
off, err = packUint8(sw.Algorithm, msg, off)
if err != nil {
return off, err
}
off, err = packUint8(sw.Labels, msg, off)
if err != nil {
return off, err
}
off, err = packUint32(sw.OrigTtl, msg, off)
if err != nil {
return off, err
}
off, err = packUint32(sw.Expiration, msg, off)
if err != nil {
return off, err
}
off, err = packUint32(sw.Inception, msg, off)
if err != nil {
return off, err
}
off, err = packUint16(sw.KeyTag, msg, off)
if err != nil {
return off, err
}
off, err = PackDomainName(sw.SignerName, msg, off, nil, false)
if err != nil {
return off, err
}
return off, nil
}
func packKeyWire(dw *dnskeyWireFmt, msg []byte) (int, error) {
// copied from zmsg.go DNSKEY packing
off, err := packUint16(dw.Flags, msg, 0)
if err != nil {
return off, err
}
off, err = packUint8(dw.Protocol, msg, off)
if err != nil {
return off, err
}
off, err = packUint8(dw.Algorithm, msg, off)
if err != nil {
return off, err
}
off, err = packStringBase64(dw.PublicKey, msg, off)
if err != nil {
return off, err
}
return off, nil
}