crypto: add basic functionality for parsing SSE-C headers (#6148)

This commit adds basic support for SSE-C / SSE-C copy.
This includes functions for determining whether SSE-C
is requested by the S3 client and functions for parsing
such HTTP headers.

All S3 SSE-C parsing errors are exported such that callers
can pattern-match to forward the correct error to S3
clients.

Further the SSE-C related internal metadata entry-keys
are added by this commit.
This commit is contained in:
Andreas Auernhammer 2018-07-18 19:49:26 +02:00 committed by Dee Koder
parent 3ec4738955
commit 758a80e39b
4 changed files with 420 additions and 4 deletions

View File

@ -27,6 +27,26 @@ var (
// ErrInvalidEncryptionMethod indicates that the specified SSE encryption method
// is not supported.
ErrInvalidEncryptionMethod = errors.New("The encryption method is not supported")
// ErrInvalidCustomerAlgorithm indicates that the specified SSE-C algorithm
// is not supported.
ErrInvalidCustomerAlgorithm = errors.New("The SSE-C algorithm is not supported")
// ErrMissingCustomerKey indicates that the HTTP headers contains no SSE-C client key.
ErrMissingCustomerKey = errors.New("The SSE-C request is missing the customer key")
// ErrMissingCustomerKeyMD5 indicates that the HTTP headers contains no SSE-C client key
// MD5 checksum.
ErrMissingCustomerKeyMD5 = errors.New("The SSE-C request is missing the customer key MD5")
// ErrInvalidCustomerKey indicates that the SSE-C client key is not valid - e.g. not a
// base64-encoded string or not 256 bits long.
ErrInvalidCustomerKey = errors.New("The SSE-C client key is invalid")
// ErrCustomerKeyMD5Mismatch indicates that the SSE-C key MD5 does not match the
// computed MD5 sum. This means that the client provided either the wrong key for
// a certain MD5 checksum or the wrong MD5 for a certain key.
ErrCustomerKeyMD5Mismatch = errors.New("The provided SSE-C key MD5 does not match the computed MD5 of the SSE-C key")
)
var (

View File

@ -15,12 +15,43 @@
package crypto
import (
"bytes"
"crypto/md5"
"encoding/base64"
"net/http"
)
// SSEHeader is the general AWS SSE HTTP header key.
const SSEHeader = "X-Amz-Server-Side-Encryption"
const (
// SSECAlgorithm is the HTTP header key referencing
// the SSE-C algorithm.
SSECAlgorithm = SSEHeader + "-Customer-Algorithm"
// SSECKey is the HTTP header key referencing the
// SSE-C client-provided key..
SSECKey = SSEHeader + "-Customer-Key"
// SSECKeyMD5 is the HTTP header key referencing
// the MD5 sum of the client-provided key.
SSECKeyMD5 = SSEHeader + "-Customer-Key-Md5"
)
const (
// SSECopyAlgorithm is the HTTP header key referencing
// the SSE-C algorithm for SSE-C copy requests.
SSECopyAlgorithm = "X-Amz-Copy-Source-Server-Side-Encryption-Customer-Algorithm"
// SSECopyKey is the HTTP header key referencing the SSE-C
// client-provided key for SSE-C copy requests.
SSECopyKey = "X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key"
// SSECopyKeyMD5 is the HTTP header key referencing the
// MD5 sum of the client key for SSE-C copy requests.
SSECopyKeyMD5 = "X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key-Md5"
)
// SSEAlgorithmAES256 is the only supported value for the SSE-S3 or SSE-C algorithm header.
// For SSE-S3 see: https://docs.aws.amazon.com/AmazonS3/latest/dev/SSEUsingRESTAPI.html
// For SSE-C see: https://docs.aws.amazon.com/AmazonS3/latest/dev/ServerSideEncryptionCustomerKeys.html
@ -47,3 +78,99 @@ func (s3) Parse(h http.Header) (err error) {
}
return
}
var (
// SSEC represents AWS SSE-C. It provides functionality to handle
// SSE-C requests.
SSEC = ssec{}
// SSECopy represents AWS SSE-C for copy requests. It provides
// functionality to handle SSE-C copy requests.
SSECopy = ssecCopy{}
)
type ssec struct{}
type ssecCopy struct{}
// IsRequested returns true if the HTTP headers contains
// at least one SSE-C header. SSE-C copy headers are ignored.
func (ssec) IsRequested(h http.Header) bool {
if _, ok := h[SSECAlgorithm]; ok {
return true
}
if _, ok := h[SSECKey]; ok {
return true
}
if _, ok := h[SSECKeyMD5]; ok {
return true
}
return false
}
// IsRequested returns true if the HTTP headers contains
// at least one SSE-C copy header. Regular SSE-C headers
// are ignored.
func (ssecCopy) IsRequested(h http.Header) bool {
if _, ok := h[SSECopyAlgorithm]; ok {
return true
}
if _, ok := h[SSECopyKey]; ok {
return true
}
if _, ok := h[SSECopyKeyMD5]; ok {
return true
}
return false
}
// Parse parses the SSE-C headers and returns the SSE-C client key
// on success. SSE-C copy headers are ignored.
func (ssec) Parse(h http.Header) (key [32]byte, err error) {
defer h.Del(SSECKey) // remove SSE-C key from headers after parsing
if h.Get(SSECAlgorithm) != SSEAlgorithmAES256 {
return key, ErrInvalidCustomerAlgorithm
}
if h.Get(SSECKey) == "" {
return key, ErrMissingCustomerKey
}
if h.Get(SSECKeyMD5) == "" {
return key, ErrMissingCustomerKeyMD5
}
clientKey, err := base64.StdEncoding.DecodeString(h.Get(SSECKey))
if err != nil || len(clientKey) != 32 { // The client key must be 256 bits long
return key, ErrInvalidCustomerKey
}
keyMD5, err := base64.StdEncoding.DecodeString(h.Get(SSECKeyMD5))
if md5Sum := md5.Sum(clientKey); err != nil || !bytes.Equal(md5Sum[:], keyMD5) {
return key, ErrCustomerKeyMD5Mismatch
}
copy(key[:], clientKey)
return key, nil
}
// Parse parses the SSE-C copy headers and returns the SSE-C client key
// on success. Regular SSE-C headers are ignored.
func (ssecCopy) Parse(h http.Header) (key [32]byte, err error) {
defer h.Del(SSECopyKey) // remove SSE-C copy key of source object from headers after parsing
if h.Get(SSECopyAlgorithm) != SSEAlgorithmAES256 {
return key, ErrInvalidCustomerAlgorithm
}
if h.Get(SSECopyKey) == "" {
return key, ErrMissingCustomerKey
}
if h.Get(SSECopyKeyMD5) == "" {
return key, ErrMissingCustomerKeyMD5
}
clientKey, err := base64.StdEncoding.DecodeString(h.Get(SSECopyKey))
if err != nil || len(clientKey) != 32 { // The client key must be 256 bits long
return key, ErrInvalidCustomerKey
}
keyMD5, err := base64.StdEncoding.DecodeString(h.Get(SSECopyKeyMD5))
if md5Sum := md5.Sum(clientKey); err != nil || !bytes.Equal(md5Sum[:], keyMD5) {
return key, ErrCustomerKeyMD5Mismatch
}
copy(key[:], clientKey)
return key, nil
}

View File

@ -19,7 +19,7 @@ import (
"testing"
)
var isRequestedTests = []struct {
var s3IsRequestedTests = []struct {
Header http.Header
Expected bool
}{
@ -30,14 +30,14 @@ var isRequestedTests = []struct {
}
func TestS3IsRequested(t *testing.T) {
for i, test := range isRequestedTests {
for i, test := range s3IsRequestedTests {
if got := S3.IsRequested(test.Header); got != test.Expected {
t.Errorf("Test %d: Wanted %v but got %v", i, test.Expected, got)
}
}
}
var parseTests = []struct {
var s3ParseTests = []struct {
Header http.Header
ExpectedErr error
}{
@ -48,9 +48,257 @@ var parseTests = []struct {
}
func TestS3Parse(t *testing.T) {
for i, test := range parseTests {
for i, test := range s3ParseTests {
if err := S3.Parse(test.Header); err != test.ExpectedErr {
t.Errorf("Test %d: Wanted '%v' but got '%v'", i, test.ExpectedErr, err)
}
}
}
var ssecIsRequestedTests = []struct {
Header http.Header
Expected bool
}{
{Header: http.Header{}, Expected: false}, // 0
{Header: http.Header{"X-Amz-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"}}, Expected: true}, // 1
{Header: http.Header{"X-Amz-Server-Side-Encryption-Customer-Key": []string{"MzJieXRlc2xvbmdzZWNyZXRrZXltdXN0cHJvdmlkZWQ="}}, Expected: true}, // 2
{Header: http.Header{"X-Amz-Server-Side-Encryption-Customer-Key-Md5": []string{"7PpPLAK26ONlVUGOWlusfg=="}}, Expected: true}, // 3
{
Header: http.Header{
"X-Amz-Server-Side-Encryption-Customer-Algorithm": []string{""},
"X-Amz-Server-Side-Encryption-Customer-Key": []string{""},
"X-Amz-Server-Side-Encryption-Customer-Key-Md5": []string{""},
},
Expected: true,
}, // 4
{
Header: http.Header{
"X-Amz-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"},
"X-Amz-Server-Side-Encryption-Customer-Key": []string{"MzJieXRlc2xvbmdzZWNyZXRrZXltdXN0cHJvdmlkZWQ="},
"X-Amz-Server-Side-Encryption-Customer-Key-Md5": []string{"7PpPLAK26ONlVUGOWlusfg=="},
},
Expected: true,
}, // 5
{
Header: http.Header{
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"},
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key": []string{"MzJieXRlc2xvbmdzZWNyZXRrZXltdXN0cHJvdmlkZWQ="},
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key-Md5": []string{"7PpPLAK26ONlVUGOWlusfg=="},
},
Expected: false,
}, // 6
}
func TestSSECIsRequested(t *testing.T) {
for i, test := range ssecIsRequestedTests {
if got := SSEC.IsRequested(test.Header); got != test.Expected {
t.Errorf("Test %d: Wanted %v but got %v", i, test.Expected, got)
}
}
}
var ssecCopyIsRequestedTests = []struct {
Header http.Header
Expected bool
}{
{Header: http.Header{}, Expected: false}, // 0
{Header: http.Header{"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"}}, Expected: true}, // 1
{Header: http.Header{"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key": []string{"MzJieXRlc2xvbmdzZWNyZXRrZXltdXN0cHJvdmlkZWQ="}}, Expected: true}, // 2
{Header: http.Header{"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key-Md5": []string{"7PpPLAK26ONlVUGOWlusfg=="}}, Expected: true}, // 3
{
Header: http.Header{
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Algorithm": []string{""},
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key": []string{""},
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key-Md5": []string{""},
},
Expected: true,
}, // 4
{
Header: http.Header{
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"},
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key": []string{"MzJieXRlc2xvbmdzZWNyZXRrZXltdXN0cHJvdmlkZWQ="},
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key-Md5": []string{"7PpPLAK26ONlVUGOWlusfg=="},
},
Expected: true,
}, // 5
{
Header: http.Header{
"X-Amz-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"},
"X-Amz-Server-Side-Encryption-Customer-Key": []string{"MzJieXRlc2xvbmdzZWNyZXRrZXltdXN0cHJvdmlkZWQ="},
"X-Amz-Server-Side-Encryption-Customer-Key-Md5": []string{"7PpPLAK26ONlVUGOWlusfg=="},
},
Expected: false,
}, // 6
}
func TestSSECopyIsRequested(t *testing.T) {
for i, test := range ssecCopyIsRequestedTests {
if got := SSECopy.IsRequested(test.Header); got != test.Expected {
t.Errorf("Test %d: Wanted %v but got %v", i, test.Expected, got)
}
}
}
var ssecParseTests = []struct {
Header http.Header
ExpectedErr error
}{
{
Header: http.Header{
"X-Amz-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"},
"X-Amz-Server-Side-Encryption-Customer-Key": []string{"MzJieXRlc2xvbmdzZWNyZXRrZXltdXN0cHJvdmlkZWQ="},
"X-Amz-Server-Side-Encryption-Customer-Key-Md5": []string{"7PpPLAK26ONlVUGOWlusfg=="},
},
ExpectedErr: nil, // 0
},
{
Header: http.Header{
"X-Amz-Server-Side-Encryption-Customer-Algorithm": []string{"AES-256"}, // invalid algorithm
"X-Amz-Server-Side-Encryption-Customer-Key": []string{"MzJieXRlc2xvbmdzZWNyZXRrZXltdXN0cHJvdmlkZWQ="},
"X-Amz-Server-Side-Encryption-Customer-Key-Md5": []string{"7PpPLAK26ONlVUGOWlusfg=="},
},
ExpectedErr: ErrInvalidCustomerAlgorithm, // 1
},
{
Header: http.Header{
"X-Amz-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"},
"X-Amz-Server-Side-Encryption-Customer-Key": []string{""}, // no client key
"X-Amz-Server-Side-Encryption-Customer-Key-Md5": []string{"7PpPLAK26ONlVUGOWlusfg=="},
},
ExpectedErr: ErrMissingCustomerKey, // 2
},
{
Header: http.Header{
"X-Amz-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"},
"X-Amz-Server-Side-Encryption-Customer-Key": []string{"MzJieXRlc2xvbmdzZWNyZXRr.ZXltdXN0cHJvdmlkZWQ="}, // invalid key
"X-Amz-Server-Side-Encryption-Customer-Key-Md5": []string{"7PpPLAK26ONlVUGOWlusfg=="},
},
ExpectedErr: ErrInvalidCustomerKey, // 3
},
{
Header: http.Header{
"X-Amz-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"},
"X-Amz-Server-Side-Encryption-Customer-Key": []string{"MzJieXRlc2xvbmdzZWNyZXRrZXltdXN0cHJvdmlkZWQ="},
"X-Amz-Server-Side-Encryption-Customer-Key-Md5": []string{""}, // no key MD5
},
ExpectedErr: ErrMissingCustomerKeyMD5, // 4
},
{
Header: http.Header{
"X-Amz-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"},
"X-Amz-Server-Side-Encryption-Customer-Key": []string{"DzJieXRlc2xvbmdzZWNyZXRrZXltdXN0cHJvdmlkZWQ="}, // wrong client key
"X-Amz-Server-Side-Encryption-Customer-Key-Md5": []string{"7PpPLAK26ONlVUGOWlusfg=="},
},
ExpectedErr: ErrCustomerKeyMD5Mismatch, // 5
},
{
Header: http.Header{
"X-Amz-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"},
"X-Amz-Server-Side-Encryption-Customer-Key": []string{"MzJieXRlc2xvbmdzZWNyZXRrZXltdXN0cHJvdmlkZWQ="},
"X-Amz-Server-Side-Encryption-Customer-Key-Md5": []string{".7PpPLAK26ONlVUGOWlusfg=="}, // wrong key MD5
},
ExpectedErr: ErrCustomerKeyMD5Mismatch, // 6
},
}
func TestSSECParse(t *testing.T) {
var zeroKey [32]byte
for i, test := range ssecParseTests {
key, err := SSEC.Parse(test.Header)
if err != test.ExpectedErr {
t.Errorf("Test %d: want error '%v' but got '%v'", i, test.ExpectedErr, err)
}
if err != nil && key != zeroKey {
t.Errorf("Test %d: parsing failed and client key is not zero key", i)
}
if err == nil && key == zeroKey {
t.Errorf("Test %d: parsed client key is zero key", i)
}
if _, ok := test.Header[SSECKey]; ok {
t.Errorf("Test %d: client key is not removed from HTTP headers after parsing", i)
}
}
}
var ssecCopyParseTests = []struct {
Header http.Header
ExpectedErr error
}{
{
Header: http.Header{
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"},
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key": []string{"MzJieXRlc2xvbmdzZWNyZXRrZXltdXN0cHJvdmlkZWQ="},
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key-Md5": []string{"7PpPLAK26ONlVUGOWlusfg=="},
},
ExpectedErr: nil, // 0
},
{
Header: http.Header{
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Algorithm": []string{"AES-256"}, // invalid algorithm
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key": []string{"MzJieXRlc2xvbmdzZWNyZXRrZXltdXN0cHJvdmlkZWQ="},
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key-Md5": []string{"7PpPLAK26ONlVUGOWlusfg=="},
},
ExpectedErr: ErrInvalidCustomerAlgorithm, // 1
},
{
Header: http.Header{
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"},
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key": []string{""}, // no client key
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key-Md5": []string{"7PpPLAK26ONlVUGOWlusfg=="},
},
ExpectedErr: ErrMissingCustomerKey, // 2
},
{
Header: http.Header{
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"},
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key": []string{"MzJieXRlc2xvbmdzZWNyZXRr.ZXltdXN0cHJvdmlkZWQ="}, // invalid key
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key-Md5": []string{"7PpPLAK26ONlVUGOWlusfg=="},
},
ExpectedErr: ErrInvalidCustomerKey, // 3
},
{
Header: http.Header{
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"},
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key": []string{"MzJieXRlc2xvbmdzZWNyZXRrZXltdXN0cHJvdmlkZWQ="},
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key-Md5": []string{""}, // no key MD5
},
ExpectedErr: ErrMissingCustomerKeyMD5, // 4
},
{
Header: http.Header{
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"},
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key": []string{"DzJieXRlc2xvbmdzZWNyZXRrZXltdXN0cHJvdmlkZWQ="}, // wrong client key
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key-Md5": []string{"7PpPLAK26ONlVUGOWlusfg=="},
},
ExpectedErr: ErrCustomerKeyMD5Mismatch, // 5
},
{
Header: http.Header{
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Algorithm": []string{"AES256"},
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key": []string{"MzJieXRlc2xvbmdzZWNyZXRrZXltdXN0cHJvdmlkZWQ="},
"X-Amz-Copy-Source-Server-Side-Encryption-Customer-Key-Md5": []string{".7PpPLAK26ONlVUGOWlusfg=="}, // wrong key MD5
},
ExpectedErr: ErrCustomerKeyMD5Mismatch, // 6
},
}
func TestSSECopyParse(t *testing.T) {
var zeroKey [32]byte
for i, test := range ssecCopyParseTests {
key, err := SSECopy.Parse(test.Header)
if err != test.ExpectedErr {
t.Errorf("Test %d: want error '%v' but got '%v'", i, test.ExpectedErr, err)
}
if err != nil && key != zeroKey {
t.Errorf("Test %d: parsing failed and client key is not zero key", i)
}
if err == nil && key == zeroKey {
t.Errorf("Test %d: parsed client key is zero key", i)
}
if _, ok := test.Header[SSECKey]; ok {
t.Errorf("Test %d: client key is not removed from HTTP headers after parsing", i)
}
}
}

View File

@ -25,11 +25,24 @@ import (
)
const (
// SSEIV is the metadata key referencing the random initialization
// vector (IV) used for SSE-S3 and SSE-C key derivation.
SSEIV = "X-Minio-Internal-Server-Side-Encryption-Iv"
// SSESealAlgorithm is the metadata key referencing the algorithm
// used by SSE-C and SSE-S3 to encrypt the object.
SSESealAlgorithm = "X-Minio-Internal-Server-Side-Encryption-Seal-Algorithm"
// SSECSealKey is the metadata key referencing the sealed object-key for SSE-C.
SSECSealKey = "X-Minio-Internal-Server-Side-Encryption-Sealed-Key"
// S3SealedKey is the metadata key referencing the sealed object-key for SSE-S3.
S3SealedKey = "X-Minio-Internal-Server-Side-Encryption-S3-Sealed-Key"
// S3KMSKeyID is the metadata key referencing the KMS key-id used to
// generate/decrypt the S3-KMS-Sealed-Key. It is only used for SSE-S3 + KMS.
S3KMSKeyID = "X-Minio-Internal-Server-Side-Encryption-S3-Kms-Key-Id"
// S3KMSSealedKey is the metadata key referencing the encrypted key generated
// by KMS. It is only used for SSE-S3 + KMS.
S3KMSSealedKey = "X-Minio-Internal-Server-Side-Encryption-S3-Kms-Sealed-Key"
@ -57,6 +70,14 @@ func EncryptSinglePart(r io.Reader, key ObjectKey) io.Reader {
return r
}
// EncryptMultiPart encrypts an io.Reader which must be the body of
// multi-part PUT request. It derives an unique encryption key from
// the partID and the object key.
func EncryptMultiPart(r io.Reader, partID int, key ObjectKey) io.Reader {
partKey := key.DerivePartKey(uint32(partID))
return EncryptSinglePart(r, ObjectKey(partKey))
}
// DecryptSinglePart decrypts an io.Writer which must an object
// uploaded with the single-part PUT API. The offset and length
// specify the requested range.