OP#792 initial commit after fork

internal/bucket/encryption/bucket-sse-config.go

@@ -0,0 +1,171 @@
+// Copyright (c) 2015-2021 MinIO, Inc.
+//
+// This file is part of MinIO Object Storage stack
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package sse
+
+import (
+	"encoding/xml"
+	"errors"
+	"io"
+	"net/http"
+	"strings"
+
+	"github.com/minio/minio/internal/crypto"
+	xhttp "github.com/minio/minio/internal/http"
+)
+
+const (
+	// AES256 is used with SSE-S3
+	AES256 Algorithm = "AES256"
+	// AWSKms is used with SSE-KMS
+	AWSKms Algorithm = "aws:kms"
+)
+
+// Algorithm - represents valid SSE algorithms supported; currently only AES256 is supported
+type Algorithm string
+
+// UnmarshalXML - Unmarshals XML tag to valid SSE algorithm
+func (alg *Algorithm) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
+	var s string
+	if err := d.DecodeElement(&s, &start); err != nil {
+		return err
+	}
+
+	switch s {
+	case string(AES256):
+		*alg = AES256
+	case string(AWSKms):
+		*alg = AWSKms
+	default:
+		return errors.New("Unknown SSE algorithm")
+	}
+
+	return nil
+}
+
+// MarshalXML - Marshals given SSE algorithm to valid XML
+func (alg *Algorithm) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
+	return e.EncodeElement(string(*alg), start)
+}
+
+// EncryptionAction - for ApplyServerSideEncryptionByDefault XML tag
+type EncryptionAction struct {
+	Algorithm   Algorithm `xml:"SSEAlgorithm,omitempty"`
+	MasterKeyID string    `xml:"KMSMasterKeyID,omitempty"`
+}
+
+// Rule - for ServerSideEncryptionConfiguration XML tag
+type Rule struct {
+	DefaultEncryptionAction EncryptionAction `xml:"ApplyServerSideEncryptionByDefault"`
+}
+
+const xmlNS = "http://s3.amazonaws.com/doc/2006-03-01/"
+
+// BucketSSEConfig - represents default bucket encryption configuration
+type BucketSSEConfig struct {
+	XMLNS   string   `xml:"xmlns,attr,omitempty"`
+	XMLName xml.Name `xml:"ServerSideEncryptionConfiguration"`
+	Rules   []Rule   `xml:"Rule"`
+}
+
+// ParseBucketSSEConfig - Decodes given XML to a valid default bucket encryption config
+func ParseBucketSSEConfig(r io.Reader) (*BucketSSEConfig, error) {
+	var config BucketSSEConfig
+	err := xml.NewDecoder(r).Decode(&config)
+	if err != nil {
+		return nil, err
+	}
+
+	// Validates server-side encryption config rules
+	// Only one rule is allowed on AWS S3
+	if len(config.Rules) != 1 {
+		return nil, errors.New("only one server-side encryption rule is allowed at a time")
+	}
+
+	for _, rule := range config.Rules {
+		switch rule.DefaultEncryptionAction.Algorithm {
+		case AES256:
+			if rule.DefaultEncryptionAction.MasterKeyID != "" {
+				return nil, errors.New("MasterKeyID is allowed with aws:kms only")
+			}
+		case AWSKms:
+			keyID := rule.DefaultEncryptionAction.MasterKeyID
+			if keyID == "" {
+				return nil, errors.New("MasterKeyID is missing with aws:kms")
+			}
+			spaces := strings.HasPrefix(keyID, " ") || strings.HasSuffix(keyID, " ")
+			if spaces {
+				return nil, errors.New("MasterKeyID contains unsupported characters")
+			}
+		}
+	}
+
+	if config.XMLNS == "" {
+		config.XMLNS = xmlNS
+	}
+	return &config, nil
+}
+
+// ApplyOptions ask for specific features to be enabled,
+// when bucketSSEConfig is empty.
+type ApplyOptions struct {
+	AutoEncrypt bool
+}
+
+// Apply applies the SSE bucket configuration on the given HTTP headers and
+// sets the specified SSE headers.
+//
+// Apply does not overwrite any existing SSE headers. Further, it will
+// set minimal SSE-KMS headers if autoEncrypt is true and the BucketSSEConfig
+// is nil.
+func (b *BucketSSEConfig) Apply(headers http.Header, opts ApplyOptions) {
+	if crypto.Requested(headers) {
+		return
+	}
+	if b == nil {
+		if opts.AutoEncrypt {
+			headers.Set(xhttp.AmzServerSideEncryption, xhttp.AmzEncryptionKMS)
+		}
+		return
+	}
+
+	switch b.Algo() {
+	case xhttp.AmzEncryptionAES:
+		headers.Set(xhttp.AmzServerSideEncryption, xhttp.AmzEncryptionAES)
+	case xhttp.AmzEncryptionKMS:
+		headers.Set(xhttp.AmzServerSideEncryption, xhttp.AmzEncryptionKMS)
+		headers.Set(xhttp.AmzServerSideEncryptionKmsID, b.KeyID())
+	}
+}
+
+// Algo returns the SSE algorithm specified by the SSE configuration.
+func (b *BucketSSEConfig) Algo() Algorithm {
+	for _, rule := range b.Rules {
+		return rule.DefaultEncryptionAction.Algorithm
+	}
+	return ""
+}
+
+// KeyID returns the KMS key ID specified by the SSE configuration.
+// If the SSE configuration does not specify SSE-KMS it returns an
+// empty key ID.
+func (b *BucketSSEConfig) KeyID() string {
+	for _, rule := range b.Rules {
+		return strings.TrimPrefix(rule.DefaultEncryptionAction.MasterKeyID, crypto.ARNPrefix)
+	}
+	return ""
+}