minio/cmd/signature-v4.go
Andreas Auernhammer c1a49be639
use crypto/sha256 for FIPS 140-2 compliance (#11623)
This commit replaces the usage of
github.com/minio/sha256-simd with crypto/sha256
of the standard library in all non-performance
critical paths.

This is necessary for FIPS 140-2 compliance which
requires that all crypto. primitives are implemented
by a FIPS-validated module.

Go can use the Google FIPS module. The boringcrypto
branch of the Go standard library uses the BoringSSL
FIPS module to implement crypto. primitives like AES
or SHA256.

We only keep github.com/minio/sha256-simd when computing
the content-SHA256 of an object. Therefore, this commit
relies on a build tag `fips`.

When MinIO is compiled without the `fips` flag it will
use github.com/minio/sha256-simd. When MinIO is compiled
with the fips flag (go build --tags "fips") then MinIO
uses crypto/sha256 to compute the content-SHA256.
2021-02-24 09:00:15 -08:00

393 lines
12 KiB
Go

/*
* MinIO Cloud Storage, (C) 2015, 2016, 2017 MinIO, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// Package cmd This file implements helper functions to validate AWS
// Signature Version '4' authorization header.
//
// This package provides comprehensive helpers for following signature
// types.
// - Based on Authorization header.
// - Based on Query parameters.
// - Based on Form POST policy.
package cmd
import (
"bytes"
"crypto/sha256"
"crypto/subtle"
"encoding/hex"
"net/http"
"net/url"
"sort"
"strconv"
"strings"
"time"
"github.com/minio/minio-go/v7/pkg/s3utils"
"github.com/minio/minio-go/v7/pkg/set"
xhttp "github.com/minio/minio/cmd/http"
)
// AWS Signature Version '4' constants.
const (
signV4Algorithm = "AWS4-HMAC-SHA256"
iso8601Format = "20060102T150405Z"
yyyymmdd = "20060102"
)
type serviceType string
const (
serviceS3 serviceType = "s3"
serviceSTS serviceType = "sts"
)
// getCanonicalHeaders generate a list of request headers with their values
func getCanonicalHeaders(signedHeaders http.Header) string {
var headers []string
vals := make(http.Header)
for k, vv := range signedHeaders {
headers = append(headers, strings.ToLower(k))
vals[strings.ToLower(k)] = vv
}
sort.Strings(headers)
var buf bytes.Buffer
for _, k := range headers {
buf.WriteString(k)
buf.WriteByte(':')
for idx, v := range vals[k] {
if idx > 0 {
buf.WriteByte(',')
}
buf.WriteString(signV4TrimAll(v))
}
buf.WriteByte('\n')
}
return buf.String()
}
// getSignedHeaders generate a string i.e alphabetically sorted, semicolon-separated list of lowercase request header names
func getSignedHeaders(signedHeaders http.Header) string {
var headers []string
for k := range signedHeaders {
headers = append(headers, strings.ToLower(k))
}
sort.Strings(headers)
return strings.Join(headers, ";")
}
// getCanonicalRequest generate a canonical request of style
//
// canonicalRequest =
// <HTTPMethod>\n
// <CanonicalURI>\n
// <CanonicalQueryString>\n
// <CanonicalHeaders>\n
// <SignedHeaders>\n
// <HashedPayload>
//
func getCanonicalRequest(extractedSignedHeaders http.Header, payload, queryStr, urlPath, method string) string {
rawQuery := strings.Replace(queryStr, "+", "%20", -1)
encodedPath := s3utils.EncodePath(urlPath)
canonicalRequest := strings.Join([]string{
method,
encodedPath,
rawQuery,
getCanonicalHeaders(extractedSignedHeaders),
getSignedHeaders(extractedSignedHeaders),
payload,
}, "\n")
return canonicalRequest
}
// getScope generate a string of a specific date, an AWS region, and a service.
func getScope(t time.Time, region string) string {
scope := strings.Join([]string{
t.Format(yyyymmdd),
region,
string(serviceS3),
"aws4_request",
}, SlashSeparator)
return scope
}
// getStringToSign a string based on selected query values.
func getStringToSign(canonicalRequest string, t time.Time, scope string) string {
stringToSign := signV4Algorithm + "\n" + t.Format(iso8601Format) + "\n"
stringToSign = stringToSign + scope + "\n"
canonicalRequestBytes := sha256.Sum256([]byte(canonicalRequest))
stringToSign = stringToSign + hex.EncodeToString(canonicalRequestBytes[:])
return stringToSign
}
// getSigningKey hmac seed to calculate final signature.
func getSigningKey(secretKey string, t time.Time, region string, stype serviceType) []byte {
date := sumHMAC([]byte("AWS4"+secretKey), []byte(t.Format(yyyymmdd)))
regionBytes := sumHMAC(date, []byte(region))
service := sumHMAC(regionBytes, []byte(stype))
signingKey := sumHMAC(service, []byte("aws4_request"))
return signingKey
}
// getSignature final signature in hexadecimal form.
func getSignature(signingKey []byte, stringToSign string) string {
return hex.EncodeToString(sumHMAC(signingKey, []byte(stringToSign)))
}
// Check to see if Policy is signed correctly.
func doesPolicySignatureMatch(formValues http.Header) APIErrorCode {
// For SignV2 - Signature field will be valid
if _, ok := formValues["Signature"]; ok {
return doesPolicySignatureV2Match(formValues)
}
return doesPolicySignatureV4Match(formValues)
}
// compareSignatureV4 returns true if and only if both signatures
// are equal. The signatures are expected to be HEX encoded strings
// according to the AWS S3 signature V4 spec.
func compareSignatureV4(sig1, sig2 string) bool {
// The CTC using []byte(str) works because the hex encoding
// is unique for a sequence of bytes. See also compareSignatureV2.
return subtle.ConstantTimeCompare([]byte(sig1), []byte(sig2)) == 1
}
// doesPolicySignatureMatch - Verify query headers with post policy
// - http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-HTTPPOSTConstructPolicy.html
// returns ErrNone if the signature matches.
func doesPolicySignatureV4Match(formValues http.Header) APIErrorCode {
// Server region.
region := globalServerRegion
// Parse credential tag.
credHeader, s3Err := parseCredentialHeader("Credential="+formValues.Get(xhttp.AmzCredential), region, serviceS3)
if s3Err != ErrNone {
return s3Err
}
cred, _, s3Err := checkKeyValid(credHeader.accessKey)
if s3Err != ErrNone {
return s3Err
}
// Get signing key.
signingKey := getSigningKey(cred.SecretKey, credHeader.scope.date, credHeader.scope.region, serviceS3)
// Get signature.
newSignature := getSignature(signingKey, formValues.Get("Policy"))
// Verify signature.
if !compareSignatureV4(newSignature, formValues.Get(xhttp.AmzSignature)) {
return ErrSignatureDoesNotMatch
}
// Success.
return ErrNone
}
// doesPresignedSignatureMatch - Verify query headers with presigned signature
// - http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-query-string-auth.html
// returns ErrNone if the signature matches.
func doesPresignedSignatureMatch(hashedPayload string, r *http.Request, region string, stype serviceType) APIErrorCode {
// Copy request
req := *r
// Parse request query string.
pSignValues, err := parsePreSignV4(req.URL.Query(), region, stype)
if err != ErrNone {
return err
}
cred, _, s3Err := checkKeyValid(pSignValues.Credential.accessKey)
if s3Err != ErrNone {
return s3Err
}
// Extract all the signed headers along with its values.
extractedSignedHeaders, errCode := extractSignedHeaders(pSignValues.SignedHeaders, r)
if errCode != ErrNone {
return errCode
}
// If the host which signed the request is slightly ahead in time (by less than globalMaxSkewTime) the
// request should still be allowed.
if pSignValues.Date.After(UTCNow().Add(globalMaxSkewTime)) {
return ErrRequestNotReadyYet
}
if UTCNow().Sub(pSignValues.Date) > pSignValues.Expires {
return ErrExpiredPresignRequest
}
// Save the date and expires.
t := pSignValues.Date
expireSeconds := int(pSignValues.Expires / time.Second)
// Construct new query.
query := make(url.Values)
clntHashedPayload := req.URL.Query().Get(xhttp.AmzContentSha256)
if clntHashedPayload != "" {
query.Set(xhttp.AmzContentSha256, hashedPayload)
}
token := req.URL.Query().Get(xhttp.AmzSecurityToken)
if token != "" {
query.Set(xhttp.AmzSecurityToken, cred.SessionToken)
}
query.Set(xhttp.AmzAlgorithm, signV4Algorithm)
// Construct the query.
query.Set(xhttp.AmzDate, t.Format(iso8601Format))
query.Set(xhttp.AmzExpires, strconv.Itoa(expireSeconds))
query.Set(xhttp.AmzSignedHeaders, getSignedHeaders(extractedSignedHeaders))
query.Set(xhttp.AmzCredential, cred.AccessKey+SlashSeparator+pSignValues.Credential.getScope())
defaultSigParams := set.CreateStringSet(
xhttp.AmzContentSha256,
xhttp.AmzSecurityToken,
xhttp.AmzAlgorithm,
xhttp.AmzDate,
xhttp.AmzExpires,
xhttp.AmzSignedHeaders,
xhttp.AmzCredential,
xhttp.AmzSignature,
)
// Add missing query parameters if any provided in the request URL
for k, v := range req.URL.Query() {
if !defaultSigParams.Contains(k) {
query[k] = v
}
}
// Get the encoded query.
encodedQuery := query.Encode()
// Verify if date query is same.
if req.URL.Query().Get(xhttp.AmzDate) != query.Get(xhttp.AmzDate) {
return ErrSignatureDoesNotMatch
}
// Verify if expires query is same.
if req.URL.Query().Get(xhttp.AmzExpires) != query.Get(xhttp.AmzExpires) {
return ErrSignatureDoesNotMatch
}
// Verify if signed headers query is same.
if req.URL.Query().Get(xhttp.AmzSignedHeaders) != query.Get(xhttp.AmzSignedHeaders) {
return ErrSignatureDoesNotMatch
}
// Verify if credential query is same.
if req.URL.Query().Get(xhttp.AmzCredential) != query.Get(xhttp.AmzCredential) {
return ErrSignatureDoesNotMatch
}
// Verify if sha256 payload query is same.
if clntHashedPayload != "" && clntHashedPayload != query.Get(xhttp.AmzContentSha256) {
return ErrContentSHA256Mismatch
}
// Verify if security token is correct.
if token != "" && subtle.ConstantTimeCompare([]byte(token), []byte(cred.SessionToken)) != 1 {
return ErrInvalidToken
}
/// Verify finally if signature is same.
// Get canonical request.
presignedCanonicalReq := getCanonicalRequest(extractedSignedHeaders, hashedPayload, encodedQuery, req.URL.Path, req.Method)
// Get string to sign from canonical request.
presignedStringToSign := getStringToSign(presignedCanonicalReq, t, pSignValues.Credential.getScope())
// Get hmac presigned signing key.
presignedSigningKey := getSigningKey(cred.SecretKey, pSignValues.Credential.scope.date,
pSignValues.Credential.scope.region, stype)
// Get new signature.
newSignature := getSignature(presignedSigningKey, presignedStringToSign)
// Verify signature.
if !compareSignatureV4(req.URL.Query().Get(xhttp.AmzSignature), newSignature) {
return ErrSignatureDoesNotMatch
}
return ErrNone
}
// doesSignatureMatch - Verify authorization header with calculated header in accordance with
// - http://docs.aws.amazon.com/AmazonS3/latest/API/sig-v4-authenticating-requests.html
// returns ErrNone if signature matches.
func doesSignatureMatch(hashedPayload string, r *http.Request, region string, stype serviceType) APIErrorCode {
// Copy request.
req := *r
// Save authorization header.
v4Auth := req.Header.Get(xhttp.Authorization)
// Parse signature version '4' header.
signV4Values, err := parseSignV4(v4Auth, region, stype)
if err != ErrNone {
return err
}
// Extract all the signed headers along with its values.
extractedSignedHeaders, errCode := extractSignedHeaders(signV4Values.SignedHeaders, r)
if errCode != ErrNone {
return errCode
}
cred, _, s3Err := checkKeyValid(signV4Values.Credential.accessKey)
if s3Err != ErrNone {
return s3Err
}
// Extract date, if not present throw error.
var date string
if date = req.Header.Get(xhttp.AmzDate); date == "" {
if date = r.Header.Get(xhttp.Date); date == "" {
return ErrMissingDateHeader
}
}
// Parse date header.
t, e := time.Parse(iso8601Format, date)
if e != nil {
return ErrMalformedDate
}
// Query string.
queryStr := req.URL.Query().Encode()
// Get canonical request.
canonicalRequest := getCanonicalRequest(extractedSignedHeaders, hashedPayload, queryStr, req.URL.Path, req.Method)
// Get string to sign from canonical request.
stringToSign := getStringToSign(canonicalRequest, t, signV4Values.Credential.getScope())
// Get hmac signing key.
signingKey := getSigningKey(cred.SecretKey, signV4Values.Credential.scope.date,
signV4Values.Credential.scope.region, stype)
// Calculate signature.
newSignature := getSignature(signingKey, stringToSign)
// Verify if signature match.
if !compareSignatureV4(newSignature, signV4Values.Signature) {
return ErrSignatureDoesNotMatch
}
// Return error none.
return ErrNone
}