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https://github.com/minio/minio.git
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signature: Use a layered approach for signature verification.
Signature calculation has now moved out from being a package to top-level as a layered mechanism. In case of payload calculation with body, go-routines are initiated to simultaneously write and calculate shasum. Errors are sent over the writer so that the lower layer removes the temporary files properly.
This commit is contained in:
Harshavardhana
391
signature-v4.go
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391
signature-v4.go
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/*
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* Minio Cloud Storage, (C) 2015, 2016 Minio, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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// This file implements helper functions to validate AWS
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// Signature Version '4' authorization header.
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//
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// This package provides comprehensive helpers for following signature
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// types.
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// - Based on Authorization header.
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// - Based on Query parameters.
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// - Based on Form POST policy.
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package main
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import (
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"bytes"
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"encoding/hex"
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"net/http"
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"net/url"
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"sort"
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"strconv"
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"strings"
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"time"
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"github.com/minio/minio/pkg/crypto/sha256"
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"github.com/minio/minio/pkg/probe"
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)
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// AWS Signature Version '4' constants.
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const (
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signV4Algorithm = "AWS4-HMAC-SHA256"
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iso8601Format = "20060102T150405Z"
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yyyymmdd = "20060102"
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)
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// getCanonicalHeaders generate a list of request headers with their values
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func getCanonicalHeaders(signedHeaders http.Header, host string) string {
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var headers []string
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vals := make(http.Header)
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for k, vv := range signedHeaders {
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headers = append(headers, strings.ToLower(k))
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vals[strings.ToLower(k)] = vv
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}
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headers = append(headers, "host")
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sort.Strings(headers)
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var buf bytes.Buffer
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for _, k := range headers {
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buf.WriteString(k)
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buf.WriteByte(':')
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switch {
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case k == "host":
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buf.WriteString(host)
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fallthrough
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default:
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for idx, v := range vals[k] {
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if idx > 0 {
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buf.WriteByte(',')
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}
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buf.WriteString(v)
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}
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buf.WriteByte('\n')
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}
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}
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return buf.String()
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}
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// getSignedHeaders generate a string i.e alphabetically sorted, semicolon-separated list of lowercase request header names
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func getSignedHeaders(signedHeaders http.Header) string {
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var headers []string
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for k := range signedHeaders {
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headers = append(headers, strings.ToLower(k))
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}
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headers = append(headers, "host")
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sort.Strings(headers)
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return strings.Join(headers, ";")
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}
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// getCanonicalRequest generate a canonical request of style
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//
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// canonicalRequest =
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// <HTTPMethod>\n
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// <CanonicalURI>\n
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// <CanonicalQueryString>\n
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// <CanonicalHeaders>\n
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// <SignedHeaders>\n
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// <HashedPayload>
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//
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func getCanonicalRequest(extractedSignedHeaders http.Header, payload, queryStr, urlPath, method, host string) string {
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rawQuery := strings.Replace(queryStr, "+", "%20", -1)
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encodedPath := getURLEncodedName(urlPath)
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// Convert any space strings back to "+".
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encodedPath = strings.Replace(encodedPath, "+", "%20", -1)
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canonicalRequest := strings.Join([]string{
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method,
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encodedPath,
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rawQuery,
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getCanonicalHeaders(extractedSignedHeaders, host),
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getSignedHeaders(extractedSignedHeaders),
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payload,
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}, "\n")
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return canonicalRequest
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}
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// getCanonicalRequest generate a canonical request of style
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//
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// canonicalRequest =
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// <HTTPMethod>\n
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// <CanonicalURI>\n
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// <CanonicalQueryString>\n
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// <CanonicalHeaders>\n
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// <SignedHeaders>\n
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// <HashedPayload>
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//
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func getPresignCanonicalRequest(extractedSignedHeaders http.Header, presignedQuery, urlPath, method, host string) string {
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rawQuery := strings.Replace(presignedQuery, "+", "%20", -1)
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encodedPath := getURLEncodedName(urlPath)
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// Convert any space strings back to "+".
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encodedPath = strings.Replace(encodedPath, "+", "%20", -1)
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canonicalRequest := strings.Join([]string{
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method,
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encodedPath,
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rawQuery,
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getCanonicalHeaders(extractedSignedHeaders, host),
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getSignedHeaders(extractedSignedHeaders),
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"UNSIGNED-PAYLOAD",
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}, "\n")
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return canonicalRequest
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}
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// getScope generate a string of a specific date, an AWS region, and a service.
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func getScope(t time.Time, region string) string {
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scope := strings.Join([]string{
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t.Format(yyyymmdd),
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region,
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"s3",
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"aws4_request",
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}, "/")
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return scope
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}
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// getStringToSign a string based on selected query values.
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func getStringToSign(canonicalRequest string, t time.Time, region string) string {
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stringToSign := signV4Algorithm + "\n" + t.Format(iso8601Format) + "\n"
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stringToSign = stringToSign + getScope(t, region) + "\n"
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canonicalRequestBytes := sha256.Sum256([]byte(canonicalRequest))
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stringToSign = stringToSign + hex.EncodeToString(canonicalRequestBytes[:])
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return stringToSign
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}
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// getSigningKey hmac seed to calculate final signature.
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func getSigningKey(secretKey string, t time.Time, region string) []byte {
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date := sumHMAC([]byte("AWS4"+secretKey), []byte(t.Format(yyyymmdd)))
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regionBytes := sumHMAC(date, []byte(region))
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service := sumHMAC(regionBytes, []byte("s3"))
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signingKey := sumHMAC(service, []byte("aws4_request"))
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return signingKey
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}
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// getSignature final signature in hexadecimal form.
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func getSignature(signingKey []byte, stringToSign string) string {
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return hex.EncodeToString(sumHMAC(signingKey, []byte(stringToSign)))
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}
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// doesPolicySignatureMatch - Verify query headers with post policy
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// - http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-HTTPPOSTConstructPolicy.html
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// returns true if matches, false otherwise. if error is not nil then it is always false
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func doesPolicySignatureMatch(formValues map[string]string) (bool, *probe.Error) {
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// Access credentials.
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cred := serverConfig.GetCredential()
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// Server region.
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region := serverConfig.GetRegion()
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// Parse credential tag.
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credHeader, err := parseCredentialHeader("Credential=" + formValues["X-Amz-Credential"])
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if err != nil {
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return false, err.Trace(formValues["X-Amz-Credential"])
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}
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// Verify if the access key id matches.
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if credHeader.accessKey != cred.AccessKeyID {
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return false, ErrInvalidAccessKey("Access key id does not match with our records.", credHeader.accessKey).Trace(credHeader.accessKey)
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}
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// Verify if the region is valid.
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if !isValidRegion(credHeader.scope.region, region) {
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return false, ErrInvalidRegion("Requested region is not recognized.", credHeader.scope.region).Trace(credHeader.scope.region)
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}
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// Parse date string.
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t, e := time.Parse(iso8601Format, formValues["X-Amz-Date"])
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if e != nil {
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return false, probe.NewError(e)
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}
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// Get signing key.
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signingKey := getSigningKey(cred.SecretAccessKey, t, region)
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// Get signature.
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newSignature := getSignature(signingKey, formValues["Policy"])
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// Verify signature.
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if newSignature != formValues["X-Amz-Signature"] {
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return false, nil
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}
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return true, nil
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}
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// doesPresignedSignatureMatch - Verify query headers with presigned signature
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// - http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-query-string-auth.html
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// returns true if matches, false otherwise. if error is not nil then it is always false
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func doesPresignedSignatureMatch(r *http.Request) (bool, *probe.Error) {
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// Access credentials.
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cred := serverConfig.GetCredential()
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// Server region.
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region := serverConfig.GetRegion()
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// Copy request
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req := *r
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// Parse request query string.
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preSignValues, err := parsePreSignV4(req.URL.Query())
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if err != nil {
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return false, err.Trace(req.URL.String())
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}
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// Verify if the access key id matches.
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if preSignValues.Credential.accessKey != cred.AccessKeyID {
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return false, ErrInvalidAccessKey("Access key id does not match with our records.", preSignValues.Credential.accessKey).Trace(preSignValues.Credential.accessKey)
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}
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// Verify if region is valid.
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sRegion := preSignValues.Credential.scope.region
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if !isValidRegion(sRegion, region) {
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return false, ErrInvalidRegion("Requested region is not recognized.", sRegion).Trace(sRegion)
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}
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// Extract all the signed headers along with its values.
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extractedSignedHeaders := extractSignedHeaders(preSignValues.SignedHeaders, req.Header)
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// Construct new query.
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query := make(url.Values)
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query.Set("X-Amz-Algorithm", signV4Algorithm)
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if time.Now().UTC().Sub(preSignValues.Date) > time.Duration(preSignValues.Expires) {
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return false, ErrExpiredPresignRequest("Presigned request already expired, please initiate a new request.")
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}
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// Save the date and expires.
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t := preSignValues.Date
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expireSeconds := int(time.Duration(preSignValues.Expires) / time.Second)
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// Construct the query.
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query.Set("X-Amz-Date", t.Format(iso8601Format))
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query.Set("X-Amz-Expires", strconv.Itoa(expireSeconds))
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query.Set("X-Amz-SignedHeaders", getSignedHeaders(extractedSignedHeaders))
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query.Set("X-Amz-Credential", cred.AccessKeyID+"/"+getScope(t, region))
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// Save other headers available in the request parameters.
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for k, v := range req.URL.Query() {
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if strings.HasPrefix(strings.ToLower(k), "x-amz") {
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continue
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}
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query[k] = v
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}
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// Get the encoded query.
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encodedQuery := query.Encode()
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// Verify if date query is same.
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if req.URL.Query().Get("X-Amz-Date") != query.Get("X-Amz-Date") {
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return false, nil
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}
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// Verify if expires query is same.
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if req.URL.Query().Get("X-Amz-Expires") != query.Get("X-Amz-Expires") {
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return false, nil
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}
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// Verify if signed headers query is same.
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if req.URL.Query().Get("X-Amz-SignedHeaders") != query.Get("X-Amz-SignedHeaders") {
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return false, nil
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}
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// Verify if credential query is same.
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if req.URL.Query().Get("X-Amz-Credential") != query.Get("X-Amz-Credential") {
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return false, nil
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}
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/// Verify finally if signature is same.
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// Get canonical request.
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presignedCanonicalReq := getPresignCanonicalRequest(extractedSignedHeaders, encodedQuery, req.URL.Path, req.Method, req.Host)
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// Get string to sign from canonical request.
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presignedStringToSign := getStringToSign(presignedCanonicalReq, t, region)
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// Get hmac presigned signing key.
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presignedSigningKey := getSigningKey(cred.SecretAccessKey, t, region)
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// Get new signature.
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newSignature := getSignature(presignedSigningKey, presignedStringToSign)
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// Verify signature.
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if req.URL.Query().Get("X-Amz-Signature") != newSignature {
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return false, nil
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}
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return true, nil
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}
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// doesSignatureMatch - Verify authorization header with calculated header in accordance with
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// - http://docs.aws.amazon.com/AmazonS3/latest/API/sig-v4-authenticating-requests.html
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// returns true if matches, false otherwise. if error is not nil then it is always false
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func doesSignatureMatch(hashedPayload string, r *http.Request) (bool, *probe.Error) {
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// Access credentials.
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cred := serverConfig.GetCredential()
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// Server region.
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region := serverConfig.GetRegion()
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// Copy request.
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req := *r
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// Save authorization header.
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v4Auth := req.Header.Get("Authorization")
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// Parse signature version '4' header.
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signV4Values, err := parseSignV4(v4Auth)
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if err != nil {
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return false, err.Trace(v4Auth)
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}
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// Extract all the signed headers along with its values.
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extractedSignedHeaders := extractSignedHeaders(signV4Values.SignedHeaders, req.Header)
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// Verify if the access key id matches.
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if signV4Values.Credential.accessKey != cred.AccessKeyID {
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return false, ErrInvalidAccessKey("Access key id does not match with our records.", signV4Values.Credential.accessKey).Trace(signV4Values.Credential.accessKey)
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}
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// Verify if region is valid.
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sRegion := signV4Values.Credential.scope.region
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if !isValidRegion(sRegion, region) {
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return false, ErrInvalidRegion("Requested region is not recognized.", sRegion).Trace(sRegion)
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}
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// Extract date, if not present throw error.
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var date string
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if date = req.Header.Get(http.CanonicalHeaderKey("x-amz-date")); date == "" {
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if date = r.Header.Get("Date"); date == "" {
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return false, ErrMissingDateHeader("Date header is missing from the request.").Trace()
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}
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}
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// Parse date header.
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t, e := time.Parse(iso8601Format, date)
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if e != nil {
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return false, probe.NewError(e)
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}
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// Query string.
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queryStr := req.URL.Query().Encode()
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// Get canonical request.
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canonicalRequest := getCanonicalRequest(extractedSignedHeaders, hashedPayload, queryStr, req.URL.Path, req.Method, req.Host)
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// Get string to sign from canonical request.
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stringToSign := getStringToSign(canonicalRequest, t, region)
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// Get hmac signing key.
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signingKey := getSigningKey(cred.SecretAccessKey, t, region)
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// Calculate signature.
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newSignature := getSignature(signingKey, stringToSign)
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// Verify if signature match.
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if newSignature != signV4Values.Signature {
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return false, nil
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}
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return true, nil
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}
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Block a user