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minio/pkg/s3/signature4/v4-signature.go

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13 KiB

/*
* Minio Cloud Storage, (C) 2015 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 signature4 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 signature4
import (
"bytes"
"encoding/hex"
"net/http"
"net/url"
"sort"
"strconv"
"strings"
"time"
"github.com/minio/minio/pkg/crypto/sha256"
"github.com/minio/minio/pkg/probe"
)
// Sign - local variables
type Sign struct {
accessKeyID string
secretAccessKey string
region string
httpRequest *http.Request
extractedSignedHeaders http.Header
}
// AWS Signature Version '4' constants.
const (
signV4Algorithm = "AWS4-HMAC-SHA256"
iso8601Format = "20060102T150405Z"
yyyymmdd = "20060102"
)
// New - initialize a new authorization checkes.
func New(accessKeyID, secretAccessKey, region string) (*Sign, *probe.Error) {
if !isValidAccessKey.MatchString(accessKeyID) {
return nil, ErrInvalidAccessKeyID("Invalid access key id.", accessKeyID).Trace(accessKeyID)
}
if !isValidSecretKey.MatchString(secretAccessKey) {
return nil, ErrInvalidAccessKeyID("Invalid secret key.", secretAccessKey).Trace(secretAccessKey)
}
if region == "" {
return nil, ErrRegionISEmpty("Region is empty.").Trace()
}
signature := &Sign{
accessKeyID: accessKeyID,
secretAccessKey: secretAccessKey,
region: region,
}
return signature, nil
}
// SetHTTPRequestToVerify - sets the http request which needs to be verified.
func (s *Sign) SetHTTPRequestToVerify(r *http.Request) Sign {
// Do not set http request if its 'nil'.
if r == nil {
return *s
}
s.httpRequest = r
return *s
}
// getCanonicalHeaders generate a list of request headers with their values
func (s Sign) 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
}
headers = append(headers, "host")
sort.Strings(headers)
var buf bytes.Buffer
for _, k := range headers {
buf.WriteString(k)
buf.WriteByte(':')
switch {
case k == "host":
buf.WriteString(s.httpRequest.Host)
fallthrough
default:
for idx, v := range vals[k] {
if idx > 0 {
buf.WriteByte(',')
}
buf.WriteString(v)
}
buf.WriteByte('\n')
}
}
return buf.String()
}
// getSignedHeaders generate a string i.e alphabetically sorted, semicolon-separated list of lowercase request header names
func (s Sign) getSignedHeaders(signedHeaders http.Header) string {
var headers []string
for k := range signedHeaders {
headers = append(headers, strings.ToLower(k))
}
headers = append(headers, "host")
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 (s *Sign) getCanonicalRequest() string {
payload := s.httpRequest.Header.Get(http.CanonicalHeaderKey("x-amz-content-sha256"))
s.httpRequest.URL.RawQuery = strings.Replace(s.httpRequest.URL.Query().Encode(), "+", "%20", -1)
encodedPath := getURLEncodedName(s.httpRequest.URL.Path)
// Convert any space strings back to "+".
encodedPath = strings.Replace(encodedPath, "+", "%20", -1)
canonicalRequest := strings.Join([]string{
s.httpRequest.Method,
encodedPath,
s.httpRequest.URL.RawQuery,
s.getCanonicalHeaders(s.extractedSignedHeaders),
s.getSignedHeaders(s.extractedSignedHeaders),
payload,
}, "\n")
return canonicalRequest
}
// getCanonicalRequest generate a canonical request of style
//
// canonicalRequest =
// <HTTPMethod>\n
// <CanonicalURI>\n
// <CanonicalQueryString>\n
// <CanonicalHeaders>\n
// <SignedHeaders>\n
// <HashedPayload>
//
func (s Sign) getPresignedCanonicalRequest(presignedQuery string) string {
rawQuery := strings.Replace(presignedQuery, "+", "%20", -1)
encodedPath := getURLEncodedName(s.httpRequest.URL.Path)
// Convert any space strings back to "+".
encodedPath = strings.Replace(encodedPath, "+", "%20", -1)
canonicalRequest := strings.Join([]string{
s.httpRequest.Method,
encodedPath,
rawQuery,
s.getCanonicalHeaders(s.extractedSignedHeaders),
s.getSignedHeaders(s.extractedSignedHeaders),
"UNSIGNED-PAYLOAD",
}, "\n")
return canonicalRequest
}
// getScope generate a string of a specific date, an AWS region, and a service.
func (s Sign) getScope(t time.Time) string {
scope := strings.Join([]string{
t.Format(yyyymmdd),
s.region,
"s3",
"aws4_request",
}, "/")
return scope
}
// getStringToSign a string based on selected query values.
func (s Sign) getStringToSign(canonicalRequest string, t time.Time) string {
stringToSign := signV4Algorithm + "\n" + t.Format(iso8601Format) + "\n"
stringToSign = stringToSign + s.getScope(t) + "\n"
canonicalRequestBytes := sha256.Sum256([]byte(canonicalRequest))
stringToSign = stringToSign + hex.EncodeToString(canonicalRequestBytes[:])
return stringToSign
}
// getSigningKey hmac seed to calculate final signature.
func (s Sign) getSigningKey(t time.Time) []byte {
secret := s.secretAccessKey
date := sumHMAC([]byte("AWS4"+secret), []byte(t.Format(yyyymmdd)))
region := sumHMAC(date, []byte(s.region))
service := sumHMAC(region, []byte("s3"))
signingKey := sumHMAC(service, []byte("aws4_request"))
return signingKey
}
// getSignature final signature in hexadecimal form.
func (s Sign) getSignature(signingKey []byte, stringToSign string) string {
return hex.EncodeToString(sumHMAC(signingKey, []byte(stringToSign)))
}
// DoesPolicySignatureMatch - Verify query headers with post policy
// - http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-HTTPPOSTConstructPolicy.html
// returns true if matches, false otherwise. if error is not nil then it is always false
func (s *Sign) DoesPolicySignatureMatch(formValues map[string]string) (bool, *probe.Error) {
// Parse credential tag.
credential, err := parseCredential("Credential=" + formValues["X-Amz-Credential"])
if err != nil {
return false, err.Trace(formValues["X-Amz-Credential"])
}
// Verify if the access key id matches.
if credential.accessKeyID != s.accessKeyID {
return false, ErrInvalidAccessKeyID("Access key id does not match with our records.", credential.accessKeyID).Trace(credential.accessKeyID)
}
// Verify if the region is valid.
reqRegion := credential.scope.region
if !isValidRegion(reqRegion, s.region) {
return false, ErrInvalidRegion("Requested region is not recognized.", reqRegion).Trace(reqRegion)
}
// Save region.
s.region = reqRegion
// Parse date string.
t, e := time.Parse(iso8601Format, formValues["X-Amz-Date"])
if e != nil {
return false, probe.NewError(e)
}
signingKey := s.getSigningKey(t)
newSignature := s.getSignature(signingKey, formValues["Policy"])
if newSignature != formValues["X-Amz-Signature"] {
return false, nil
}
return true, nil
}
// DoesPresignedSignatureMatch - Verify query headers with presigned signature
// - http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-query-string-auth.html
// returns true if matches, false otherwise. if error is not nil then it is always false
func (s *Sign) DoesPresignedSignatureMatch() (bool, *probe.Error) {
// Parse request query string.
preSignValues, err := parsePreSignV4(s.httpRequest.URL.Query())
if err != nil {
return false, err.Trace(s.httpRequest.URL.String())
}
// Verify if the access key id matches.
if preSignValues.Credential.accessKeyID != s.accessKeyID {
return false, ErrInvalidAccessKeyID("Access key id does not match with our records.", preSignValues.Credential.accessKeyID).Trace(preSignValues.Credential.accessKeyID)
}
// Verify if region is valid.
reqRegion := preSignValues.Credential.scope.region
if !isValidRegion(reqRegion, s.region) {
return false, ErrInvalidRegion("Requested region is not recognized.", reqRegion).Trace(reqRegion)
}
// Save region.
s.region = reqRegion
// Extract all the signed headers along with its values.
s.extractedSignedHeaders = extractSignedHeaders(preSignValues.SignedHeaders, s.httpRequest.Header)
// Construct new query.
query := make(url.Values)
query.Set("X-Amz-Algorithm", signV4Algorithm)
if time.Now().UTC().Sub(preSignValues.Date) > time.Duration(preSignValues.Expires) {
return false, ErrExpiredPresignRequest("Presigned request already expired, please initiate a new request.")
}
// Save the date and expires.
t := preSignValues.Date
expireSeconds := int(time.Duration(preSignValues.Expires) / time.Second)
// Construct the query.
query.Set("X-Amz-Date", t.Format(iso8601Format))
query.Set("X-Amz-Expires", strconv.Itoa(expireSeconds))
query.Set("X-Amz-SignedHeaders", s.getSignedHeaders(s.extractedSignedHeaders))
query.Set("X-Amz-Credential", s.accessKeyID+"/"+s.getScope(t))
// Save other headers available in the request parameters.
for k, v := range s.httpRequest.URL.Query() {
if strings.HasPrefix(strings.ToLower(k), "x-amz") {
continue
}
query[k] = v
}
// Get the encoded query.
encodedQuery := query.Encode()
// Verify if date query is same.
if s.httpRequest.URL.Query().Get("X-Amz-Date") != query.Get("X-Amz-Date") {
return false, nil
}
// Verify if expires query is same.
if s.httpRequest.URL.Query().Get("X-Amz-Expires") != query.Get("X-Amz-Expires") {
return false, nil
}
// Verify if signed headers query is same.
if s.httpRequest.URL.Query().Get("X-Amz-SignedHeaders") != query.Get("X-Amz-SignedHeaders") {
return false, nil
}
// Verify if credential query is same.
if s.httpRequest.URL.Query().Get("X-Amz-Credential") != query.Get("X-Amz-Credential") {
return false, nil
}
// Verify finally if signature is same.
newSignature := s.getSignature(s.getSigningKey(t), s.getStringToSign(s.getPresignedCanonicalRequest(encodedQuery), t))
if s.httpRequest.URL.Query().Get("X-Amz-Signature") != newSignature {
return false, nil
}
return true, nil
}
// DoesSignatureMatch - Verify authorization header with calculated header in accordance with
// - http://docs.aws.amazon.com/AmazonS3/latest/API/sig-v4-authenticating-requests.html
// returns true if matches, false otherwise. if error is not nil then it is always false
func (s *Sign) DoesSignatureMatch(hashedPayload string) (bool, *probe.Error) {
// Save authorization header.
v4Auth := s.httpRequest.Header.Get("Authorization")
// Parse signature version '4' header.
signV4Values, err := parseSignV4(v4Auth)
if err != nil {
return false, err.Trace(v4Auth)
}
// Extract all the signed headers along with its values.
s.extractedSignedHeaders = extractSignedHeaders(signV4Values.SignedHeaders, s.httpRequest.Header)
// Verify if the access key id matches.
if signV4Values.Credential.accessKeyID != s.accessKeyID {
return false, ErrInvalidAccessKeyID("Access key id does not match with our records.", signV4Values.Credential.accessKeyID).Trace(signV4Values.Credential.accessKeyID)
}
// Verify if region is valid.
reqRegion := signV4Values.Credential.scope.region
if !isValidRegion(reqRegion, s.region) {
return false, ErrInvalidRegion("Requested region is not recognized.", reqRegion).Trace(reqRegion)
}
// Save region.
s.region = reqRegion
// Set input payload.
s.httpRequest.Header.Set("X-Amz-Content-Sha256", hashedPayload)
// Extract date, if not present throw error.
var date string
if date = s.httpRequest.Header.Get(http.CanonicalHeaderKey("x-amz-date")); date == "" {
if date = s.httpRequest.Header.Get("Date"); date == "" {
return false, ErrMissingDateHeader("Date header is missing from the request.").Trace()
}
}
// Parse date header.
t, e := time.Parse(iso8601Format, date)
if e != nil {
return false, probe.NewError(e)
}
// Signature version '4'.
canonicalRequest := s.getCanonicalRequest()
stringToSign := s.getStringToSign(canonicalRequest, t)
signingKey := s.getSigningKey(t)
newSignature := s.getSignature(signingKey, stringToSign)
// Verify if signature match.
if newSignature != signV4Values.Signature {
return false, nil
}
return true, nil
}