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s3proxy: add allow-multipart flag (#2420)

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This flag allows users to control wether multipart uploads
are blocked or allowed. At the moment s3proxy doesn't
encrypt multipart uploads, so there is a potential for
inadvertent data leakage. With this flag the default
behavior is changed to a more secure default one: block
multipart uploads. The previous behavior can be enabled
by setting allow-multipart.
This commit is contained in:
Otto Bittner 2023-10-09 15:18:12 +02:00 committed by GitHub
parent 005e865a13
commit c603b547db
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 253 additions and 151 deletions
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31
s3proxy/cmd/main.go
View File

@ -49,6 +49,10 @@ func main() {
logger := logger.New(logger.JSONLog, logger.VerbosityFromInt(flags.logLevel))
if flags.forwardMultipartReqs {
logger.Warnf("configured to forward multipart uploads, this may leak data to AWS")
}
if err := runServer(flags, logger); err != nil {
panic(err)
}
@ -57,7 +61,7 @@ func main() {
func runServer(flags cmdFlags, log *logger.Logger) error {
log.With(zap.String("ip", flags.ip), zap.Int("port", defaultPort), zap.String("region", flags.region)).Infof("listening")
router, err := router.New(flags.region, flags.kmsEndpoint, log)
router, err := router.New(flags.region, flags.kmsEndpoint, flags.forwardMultipartReqs, log)
if err != nil {
return fmt.Errorf("creating router: %w", err)
}
@ -96,6 +100,7 @@ func parseFlags() (cmdFlags, error) {
region := flag.String("region", defaultRegion, "AWS region in which target bucket is located")
certLocation := flag.String("cert", defaultCertLocation, "location of TLS certificate")
kmsEndpoint := flag.String("kms", "key-service.kube-system:9000", "endpoint of the KMS service to get key encryption keys from")
forwardMultipartReqs := flag.Bool("allow-multipart", false, "forward multipart requests to the target bucket; beware: this may store unencrypted data on AWS. See the documentation for more information")
level := flag.Int("level", defaultLogLevel, "log level")
flag.Parse()
@ -112,21 +117,23 @@ func parseFlags() (cmdFlags, error) {
// }
return cmdFlags{
noTLS: *noTLS,
ip: netIP.String(),
region: *region,
certLocation: *certLocation,
kmsEndpoint: *kmsEndpoint,
logLevel: *level,
noTLS: *noTLS,
ip: netIP.String(),
region: *region,
certLocation: *certLocation,
kmsEndpoint: *kmsEndpoint,
forwardMultipartReqs: *forwardMultipartReqs,
logLevel: *level,
}, nil
}
type cmdFlags struct {
noTLS bool
ip string
region string
certLocation string
kmsEndpoint string
noTLS bool
ip string
region string
certLocation string
kmsEndpoint string
forwardMultipartReqs bool
// TODO(derpsteb): enable once we are on go 1.21.
// logLevel slog.Level
logLevel int

2
s3proxy/deploy/deployment-s3proxy.yaml
View File

@ -47,7 +47,7 @@ spec:
- name: regcred
containers:
- name: s3proxy
image: ghcr.io/edgelesssys/constellation/s3proxy@sha256:2394a804e8b5ff487a55199dd83138885322a4de8e71ac7ce67b79d4ffc842b2
image: ghcr.io/edgelesssys/constellation/s3proxy:v2.12.0-pre.0.20231009141917-226cb427d0b1
args:
- "--level=-1"
ports:

1
s3proxy/internal/router/BUILD.bazel
View File

@ -4,6 +4,7 @@ load("//bazel/go:go_test.bzl", "go_test")
go_library(
name = "router",
srcs = [
"handler.go",
"object.go",
"router.go",
],

191
s3proxy/internal/router/handler.go Normal file
View File

@ -0,0 +1,191 @@
/*
Copyright (c) Edgeless Systems GmbH
SPDX-License-Identifier: AGPL-3.0-only
*/
package router
import (
"encoding/xml"
"fmt"
"io"
"net/http"
"github.com/edgelesssys/constellation/v2/internal/logger"
"github.com/edgelesssys/constellation/v2/s3proxy/internal/s3"
"go.uber.org/zap"
)
func handleGetObject(client *s3.Client, key string, bucket string, log *logger.Logger) http.HandlerFunc {
return func(w http.ResponseWriter, req *http.Request) {
log.With(zap.String("path", req.URL.Path), zap.String("method", req.Method), zap.String("host", req.Host)).Debugf("intercepting")
if req.Header.Get("Range") != "" {
log.Errorf("GetObject Range header unsupported")
http.Error(w, "s3proxy currently does not support Range headers", http.StatusNotImplemented)
return
}
obj := object{
client: client,
key: key,
bucket: bucket,
query: req.URL.Query(),
sseCustomerAlgorithm: req.Header.Get("x-amz-server-side-encryption-customer-algorithm"),
sseCustomerKey: req.Header.Get("x-amz-server-side-encryption-customer-key"),
sseCustomerKeyMD5: req.Header.Get("x-amz-server-side-encryption-customer-key-MD5"),
log: log,
}
get(obj.get)(w, req)
}
}
func handlePutObject(client *s3.Client, key string, bucket string, log *logger.Logger) http.HandlerFunc {
return func(w http.ResponseWriter, req *http.Request) {
log.With(zap.String("path", req.URL.Path), zap.String("method", req.Method), zap.String("host", req.Host)).Debugf("intercepting")
body, err := io.ReadAll(req.Body)
if err != nil {
log.With(zap.Error(err)).Errorf("PutObject")
http.Error(w, fmt.Sprintf("reading body: %s", err.Error()), http.StatusInternalServerError)
return
}
clientDigest := req.Header.Get("x-amz-content-sha256")
serverDigest := sha256sum(body)
// There may be a client that wants to test that incorrect content digests result in API errors.
// For encrypting the body we have to recalculate the content digest.
// If the client intentionally sends a mismatching content digest, we would take the client request, rewrap it,
// calculate the correct digest for the new body and NOT get an error.
// Thus we have to check incoming requets for matching content digests.
// UNSIGNED-PAYLOAD can be used to disabled payload signing. In that case we don't check the content digest.
if clientDigest != "" && clientDigest != "UNSIGNED-PAYLOAD" && clientDigest != serverDigest {
log.Debugf("PutObject", "error", "x-amz-content-sha256 mismatch")
// The S3 API responds with an XML formatted error message.
mismatchErr := NewContentSHA256MismatchError(clientDigest, serverDigest)
marshalled, err := xml.Marshal(mismatchErr)
if err != nil {
log.With(zap.Error(err)).Errorf("PutObject")
http.Error(w, fmt.Sprintf("marshalling error: %s", err.Error()), http.StatusInternalServerError)
return
}
http.Error(w, string(marshalled), http.StatusBadRequest)
return
}
metadata := getMetadataHeaders(req.Header)
raw := req.Header.Get("x-amz-object-lock-retain-until-date")
retentionTime, err := parseRetentionTime(raw)
if err != nil {
log.With(zap.String("data", raw), zap.Error(err)).Errorf("parsing lock retention time")
http.Error(w, fmt.Sprintf("parsing x-amz-object-lock-retain-until-date: %s", err.Error()), http.StatusInternalServerError)
return
}
err = validateContentMD5(req.Header.Get("content-md5"), body)
if err != nil {
log.With(zap.Error(err)).Errorf("validating content md5")
http.Error(w, fmt.Sprintf("validating content md5: %s", err.Error()), http.StatusBadRequest)
return
}
obj := object{
client: client,
key: key,
bucket: bucket,
data: body,
query: req.URL.Query(),
tags: req.Header.Get("x-amz-tagging"),
contentType: req.Header.Get("Content-Type"),
metadata: metadata,
objectLockLegalHoldStatus: req.Header.Get("x-amz-object-lock-legal-hold"),
objectLockMode: req.Header.Get("x-amz-object-lock-mode"),
objectLockRetainUntilDate: retentionTime,
sseCustomerAlgorithm: req.Header.Get("x-amz-server-side-encryption-customer-algorithm"),
sseCustomerKey: req.Header.Get("x-amz-server-side-encryption-customer-key"),
sseCustomerKeyMD5: req.Header.Get("x-amz-server-side-encryption-customer-key-MD5"),
log: log,
}
put(obj.put)(w, req)
}
}
func handleForwards(log *logger.Logger) http.HandlerFunc {
return func(w http.ResponseWriter, req *http.Request) {
log.With(zap.String("path", req.URL.Path), zap.String("method", req.Method), zap.String("host", req.Host)).Debugf("forwarding")
newReq := repackage(req)
httpClient := http.DefaultClient
resp, err := httpClient.Do(&newReq)
if err != nil {
log.With(zap.Error(err)).Errorf("do request")
http.Error(w, fmt.Sprintf("do request: %s", err.Error()), http.StatusInternalServerError)
return
}
defer resp.Body.Close()
for key := range resp.Header {
w.Header().Set(key, resp.Header.Get(key))
}
body, err := io.ReadAll(resp.Body)
if err != nil {
log.With(zap.Error(err)).Errorf("ReadAll")
http.Error(w, fmt.Sprintf("reading body: %s", err.Error()), http.StatusInternalServerError)
return
}
w.WriteHeader(resp.StatusCode)
if body == nil {
return
}
if _, err := w.Write(body); err != nil {
log.With(zap.Error(err)).Errorf("Write")
http.Error(w, fmt.Sprintf("writing body: %s", err.Error()), http.StatusInternalServerError)
return
}
}
}
// handleCreateMultipartUpload logs the request and blocks with an error message.
func handleCreateMultipartUpload(log *logger.Logger) http.HandlerFunc {
return func(w http.ResponseWriter, req *http.Request) {
log.With(zap.String("path", req.URL.Path), zap.String("method", req.Method), zap.String("host", req.Host)).Debugf("intercepting CreateMultipartUpload")
log.Errorf("Blocking CreateMultipartUpload request")
http.Error(w, "s3proxy is configured to block CreateMultipartUpload requests", http.StatusNotImplemented)
}
}
// handleUploadPart logs the request and blocks with an error message.
func handleUploadPart(log *logger.Logger) http.HandlerFunc {
return func(w http.ResponseWriter, req *http.Request) {
log.With(zap.String("path", req.URL.Path), zap.String("method", req.Method), zap.String("host", req.Host)).Debugf("intercepting UploadPart")
log.Errorf("Blocking UploadPart request")
http.Error(w, "s3proxy is configured to block UploadPart requests", http.StatusNotImplemented)
}
}
// handleCompleteMultipartUpload logs the request and blocks with an error message.
func handleCompleteMultipartUpload(log *logger.Logger) http.HandlerFunc {
return func(w http.ResponseWriter, req *http.Request) {
log.With(zap.String("path", req.URL.Path), zap.String("method", req.Method), zap.String("host", req.Host)).Debugf("intercepting CompleteMultipartUpload")
log.Errorf("Blocking CompleteMultipartUpload request")
http.Error(w, "s3proxy is configured to block CompleteMultipartUpload requests", http.StatusNotImplemented)
}
}
// handleAbortMultipartUpload logs the request and blocks with an error message.
func handleAbortMultipartUpload(log *logger.Logger) http.HandlerFunc {
return func(w http.ResponseWriter, req *http.Request) {
log.With(zap.String("path", req.URL.Path), zap.String("method", req.Method), zap.String("host", req.Host)).Debugf("intercepting AbortMultipartUpload")
log.Errorf("Blocking AbortMultipartUpload request")
http.Error(w, "s3proxy is configured to block AbortMultipartUpload requests", http.StatusNotImplemented)
}
}

179
s3proxy/internal/router/router.go
View File

@ -27,7 +27,6 @@ import (
"encoding/base64"
"encoding/xml"
"fmt"
"io"
"net/http"
"net/url"
"regexp"
@ -37,7 +36,6 @@ import (
"github.com/edgelesssys/constellation/v2/internal/logger"
"github.com/edgelesssys/constellation/v2/s3proxy/internal/kms"
"github.com/edgelesssys/constellation/v2/s3proxy/internal/s3"
"go.uber.org/zap"
)
const (
@ -55,11 +53,15 @@ var (
type Router struct {
region string
kek [32]byte
log *logger.Logger
// forwardMultipartReqs controls whether we forward the following requests: CreateMultipartUpload, UploadPart, CompleteMultipartUpload, AbortMultipartUpload.
// s3proxy does not implement those yet.
// Setting forwardMultipartReqs to true will forward those requests to the S3 API, otherwise we block them (secure defaults).
forwardMultipartReqs bool
log *logger.Logger
}
// New creates a new Router.
func New(region, endpoint string, log *logger.Logger) (Router, error) {
func New(region, endpoint string, forwardMultipartReqs bool, log *logger.Logger) (Router, error) {
kms := kms.New(log, endpoint)
// Get the key encryption key that encrypts all DEKs.
@ -73,7 +75,7 @@ func New(region, endpoint string, log *logger.Logger) (Router, error) {
return Router{}, fmt.Errorf("converting KEK to byte array: %w", err)
}
return Router{region: region, kek: kekArray, log: log}, nil
return Router{region: region, kek: kekArray, forwardMultipartReqs: forwardMultipartReqs, log: log}, nil
}
// Serve implements the routing logic for the s3 proxy.
@ -103,6 +105,7 @@ func (r Router) Serve(w http.ResponseWriter, req *http.Request) {
}
var h http.Handler
switch {
// intercept GetObject.
case matchingPath && req.Method == "GET" && !isUnwantedGetEndpoint(req.URL.Query()):
@ -110,6 +113,14 @@ func (r Router) Serve(w http.ResponseWriter, req *http.Request) {
// intercept PutObject.
case matchingPath && req.Method == "PUT" && !isUnwantedPutEndpoint(req.Header, req.URL.Query()):
h = handlePutObject(client, key, bucket, r.log)
case !r.forwardMultipartReqs && matchingPath && isUploadPart(req.Method, req.URL.Query()):
h = handleUploadPart(r.log)
case !r.forwardMultipartReqs && matchingPath && isCreateMultipartUpload(req.Method, req.URL.Query()):
h = handleCreateMultipartUpload(r.log)
case !r.forwardMultipartReqs && matchingPath && isCompleteMultipartUpload(req.Method, req.URL.Query()):
h = handleCompleteMultipartUpload(r.log)
case !r.forwardMultipartReqs && matchingPath && isAbortMultipartUpload(req.Method, req.URL.Query()):
h = handleAbortMultipartUpload(r.log)
// Forward all other requests.
default:
h = handleForwards(r.log)
@ -118,6 +129,31 @@ func (r Router) Serve(w http.ResponseWriter, req *http.Request) {
h.ServeHTTP(w, req)
}
func isAbortMultipartUpload(method string, query url.Values) bool {
_, uploadID := query["uploadId"]
return method == "DELETE" && uploadID
}
func isCompleteMultipartUpload(method string, query url.Values) bool {
_, multipart := query["uploadId"]
return method == "POST" && multipart
}
func isCreateMultipartUpload(method string, query url.Values) bool {
_, multipart := query["uploads"]
return method == "POST" && multipart
}
func isUploadPart(method string, query url.Values) bool {
_, partNumber := query["partNumber"]
_, uploadID := query["uploadId"]
return method == "PUT" && partNumber && uploadID
}
// ContentSHA256MismatchError is a helper struct to create an XML formatted error message.
// s3 clients might try to parse error messages, so we need to serve correctly formatted messages.
type ContentSHA256MismatchError struct {
@ -138,139 +174,6 @@ func NewContentSHA256MismatchError(clientComputedContentSHA256, s3ComputedConten
}
}
func handleGetObject(client *s3.Client, key string, bucket string, log *logger.Logger) http.HandlerFunc {
return func(w http.ResponseWriter, req *http.Request) {
log.With(zap.String("path", req.URL.Path), zap.String("method", req.Method), zap.String("host", req.Host)).Debugf("intercepting")
if req.Header.Get("Range") != "" {
log.Errorf("GetObject Range header unsupported")
http.Error(w, "s3proxy currently does not support Range headers", http.StatusNotImplemented)
return
}
obj := object{
client: client,
key: key,
bucket: bucket,
query: req.URL.Query(),
sseCustomerAlgorithm: req.Header.Get("x-amz-server-side-encryption-customer-algorithm"),
sseCustomerKey: req.Header.Get("x-amz-server-side-encryption-customer-key"),
sseCustomerKeyMD5: req.Header.Get("x-amz-server-side-encryption-customer-key-MD5"),
log: log,
}
get(obj.get)(w, req)
}
}
func handlePutObject(client *s3.Client, key string, bucket string, log *logger.Logger) http.HandlerFunc {
return func(w http.ResponseWriter, req *http.Request) {
log.With(zap.String("path", req.URL.Path), zap.String("method", req.Method), zap.String("host", req.Host)).Debugf("intercepting")
body, err := io.ReadAll(req.Body)
if err != nil {
log.With(zap.Error(err)).Errorf("PutObject")
http.Error(w, fmt.Sprintf("reading body: %s", err.Error()), http.StatusInternalServerError)
return
}
clientDigest := req.Header.Get("x-amz-content-sha256")
serverDigest := sha256sum(body)
// There may be a client that wants to test that incorrect content digests result in API errors.
// For encrypting the body we have to recalculate the content digest.
// If the client intentionally sends a mismatching content digest, we would take the client request, rewrap it,
// calculate the correct digest for the new body and NOT get an error.
// Thus we have to check incoming requets for matching content digests.
// UNSIGNED-PAYLOAD can be used to disabled payload signing. In that case we don't check the content digest.
if clientDigest != "" && clientDigest != "UNSIGNED-PAYLOAD" && clientDigest != serverDigest {
log.Debugf("PutObject", "error", "x-amz-content-sha256 mismatch")
// The S3 API responds with an XML formatted error message.
mismatchErr := NewContentSHA256MismatchError(clientDigest, serverDigest)
marshalled, err := xml.Marshal(mismatchErr)
if err != nil {
log.With(zap.Error(err)).Errorf("PutObject")
http.Error(w, fmt.Sprintf("marshalling error: %s", err.Error()), http.StatusInternalServerError)
return
}
http.Error(w, string(marshalled), http.StatusBadRequest)
return
}
metadata := getMetadataHeaders(req.Header)
raw := req.Header.Get("x-amz-object-lock-retain-until-date")
retentionTime, err := parseRetentionTime(raw)
if err != nil {
log.With(zap.String("data", raw), zap.Error(err)).Errorf("parsing lock retention time")
http.Error(w, fmt.Sprintf("parsing x-amz-object-lock-retain-until-date: %s", err.Error()), http.StatusInternalServerError)
return
}
err = validateContentMD5(req.Header.Get("content-md5"), body)
if err != nil {
log.With(zap.Error(err)).Errorf("validating content md5")
http.Error(w, fmt.Sprintf("validating content md5: %s", err.Error()), http.StatusBadRequest)
return
}
obj := object{
client: client,
key: key,
bucket: bucket,
data: body,
query: req.URL.Query(),
tags: req.Header.Get("x-amz-tagging"),
contentType: req.Header.Get("Content-Type"),
metadata: metadata,
objectLockLegalHoldStatus: req.Header.Get("x-amz-object-lock-legal-hold"),
objectLockMode: req.Header.Get("x-amz-object-lock-mode"),
objectLockRetainUntilDate: retentionTime,
sseCustomerAlgorithm: req.Header.Get("x-amz-server-side-encryption-customer-algorithm"),
sseCustomerKey: req.Header.Get("x-amz-server-side-encryption-customer-key"),
sseCustomerKeyMD5: req.Header.Get("x-amz-server-side-encryption-customer-key-MD5"),
log: log,
}
put(obj.put)(w, req)
}
}
func handleForwards(log *logger.Logger) http.HandlerFunc {
return func(w http.ResponseWriter, req *http.Request) {
log.With(zap.String("path", req.URL.Path), zap.String("method", req.Method), zap.String("host", req.Host)).Debugf("forwarding")
newReq := repackage(req)
httpClient := http.DefaultClient
resp, err := httpClient.Do(&newReq)
if err != nil {
log.With(zap.Error(err)).Errorf("do request")
http.Error(w, fmt.Sprintf("do request: %s", err.Error()), http.StatusInternalServerError)
return
}
defer resp.Body.Close()
for key := range resp.Header {
w.Header().Set(key, resp.Header.Get(key))
}
body, err := io.ReadAll(resp.Body)
if err != nil {
log.With(zap.Error(err)).Errorf("ReadAll")
http.Error(w, fmt.Sprintf("reading body: %s", err.Error()), http.StatusInternalServerError)
return
}
w.WriteHeader(resp.StatusCode)
if body == nil {
return
}
if _, err := w.Write(body); err != nil {
log.With(zap.Error(err)).Errorf("Write")
http.Error(w, fmt.Sprintf("writing body: %s", err.Error()), http.StatusInternalServerError)
return
}
}
}
// byteSliceToByteArray casts a byte slice to a byte array of length 32.
// It does a length check to prevent the cast from panic'ing.
func byteSliceToByteArray(input []byte) ([32]byte, error) {