OP#792 initial commit after fork
This commit is contained in:
408
cmd/signature-v4.go
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408
cmd/signature-v4.go
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// Copyright (c) 2015-2023 MinIO, Inc.
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//
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// This file is part of MinIO Object Storage stack
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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// Package cmd 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 cmd
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import (
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"bytes"
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"crypto/subtle"
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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-go/v7/pkg/s3utils"
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"github.com/minio/minio-go/v7/pkg/set"
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"github.com/minio/minio/internal/auth"
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"github.com/minio/minio/internal/hash/sha256"
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xhttp "github.com/minio/minio/internal/http"
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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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type serviceType string
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const (
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serviceS3 serviceType = "s3"
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serviceSTS serviceType = "sts"
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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) string {
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var headers []string
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vals := make(http.Header, len(signedHeaders))
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for k, vv := range signedHeaders {
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k = strings.ToLower(k)
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headers = append(headers, k)
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vals[k] = vv
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}
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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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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(signV4TrimAll(v))
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}
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buf.WriteByte('\n')
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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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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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//
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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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func getCanonicalRequest(extractedSignedHeaders http.Header, payload, queryStr, urlPath, method string) string {
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rawQuery := strings.ReplaceAll(queryStr, "+", "%20")
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encodedPath := s3utils.EncodePath(urlPath)
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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),
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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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// 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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string(serviceS3),
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"aws4_request",
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}, SlashSeparator)
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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, scope string) string {
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stringToSign := signV4Algorithm + "\n" + t.Format(iso8601Format) + "\n"
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stringToSign += scope + "\n"
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canonicalRequestBytes := sha256.Sum256([]byte(canonicalRequest))
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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, stype serviceType) []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(stype))
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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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// Check to see if Policy is signed correctly.
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func doesPolicySignatureMatch(formValues http.Header) (auth.Credentials, APIErrorCode) {
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// For SignV2 - Signature field will be valid
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if _, ok := formValues[xhttp.AmzSignatureV2]; ok {
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return doesPolicySignatureV2Match(formValues)
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}
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return doesPolicySignatureV4Match(formValues)
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}
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// compareSignatureV4 returns true if and only if both signatures
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// are equal. The signatures are expected to be HEX encoded strings
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// according to the AWS S3 signature V4 spec.
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func compareSignatureV4(sig1, sig2 string) bool {
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// The CTC using []byte(str) works because the hex encoding
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// is unique for a sequence of bytes. See also compareSignatureV2.
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return subtle.ConstantTimeCompare([]byte(sig1), []byte(sig2)) == 1
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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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//
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// returns ErrNone if the signature matches.
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func doesPolicySignatureV4Match(formValues http.Header) (auth.Credentials, APIErrorCode) {
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// Server region.
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region := globalSite.Region()
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// Parse credential tag.
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credHeader, s3Err := parseCredentialHeader("Credential="+formValues.Get(xhttp.AmzCredential), region, serviceS3)
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if s3Err != ErrNone {
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return auth.Credentials{}, s3Err
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}
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r := &http.Request{Header: formValues}
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cred, _, s3Err := checkKeyValid(r, credHeader.accessKey)
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if s3Err != ErrNone {
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return cred, s3Err
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}
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// Get signing key.
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signingKey := getSigningKey(cred.SecretKey, credHeader.scope.date, credHeader.scope.region, serviceS3)
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// Get signature.
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newSignature := getSignature(signingKey, formValues.Get("Policy"))
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// Verify signature.
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if !compareSignatureV4(newSignature, formValues.Get(xhttp.AmzSignature)) {
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return cred, ErrSignatureDoesNotMatch
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}
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// Success.
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return cred, ErrNone
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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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//
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// returns ErrNone if the signature matches.
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func doesPresignedSignatureMatch(hashedPayload string, r *http.Request, region string, stype serviceType) APIErrorCode {
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// Copy request
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req := *r
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// Parse request query string.
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pSignValues, err := parsePreSignV4(req.Form, region, stype)
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if err != ErrNone {
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return err
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}
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cred, _, s3Err := checkKeyValid(r, pSignValues.Credential.accessKey)
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if s3Err != ErrNone {
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return s3Err
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}
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// Extract all the signed headers along with its values.
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extractedSignedHeaders, errCode := extractSignedHeaders(pSignValues.SignedHeaders, r)
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if errCode != ErrNone {
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return errCode
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}
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// Check if the metadata headers are equal with signedheaders
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errMetaCode := checkMetaHeaders(extractedSignedHeaders, r)
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if errMetaCode != ErrNone {
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return errMetaCode
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}
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// If the host which signed the request is slightly ahead in time (by less than globalMaxSkewTime) the
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// request should still be allowed.
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if pSignValues.Date.After(UTCNow().Add(globalMaxSkewTime)) {
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return ErrRequestNotReadyYet
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}
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if UTCNow().Sub(pSignValues.Date) > pSignValues.Expires {
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return ErrExpiredPresignRequest
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}
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// Save the date and expires.
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t := pSignValues.Date
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expireSeconds := int(pSignValues.Expires / time.Second)
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// Construct new query.
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query := make(url.Values)
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clntHashedPayload := req.Form.Get(xhttp.AmzContentSha256)
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if clntHashedPayload != "" {
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query.Set(xhttp.AmzContentSha256, hashedPayload)
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}
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token := req.Form.Get(xhttp.AmzSecurityToken)
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if token != "" {
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query.Set(xhttp.AmzSecurityToken, cred.SessionToken)
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}
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query.Set(xhttp.AmzAlgorithm, signV4Algorithm)
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// Construct the query.
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query.Set(xhttp.AmzDate, t.Format(iso8601Format))
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query.Set(xhttp.AmzExpires, strconv.Itoa(expireSeconds))
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query.Set(xhttp.AmzSignedHeaders, strings.Join(pSignValues.SignedHeaders, ";"))
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query.Set(xhttp.AmzCredential, cred.AccessKey+SlashSeparator+pSignValues.Credential.getScope())
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defaultSigParams := set.CreateStringSet(
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xhttp.AmzContentSha256,
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xhttp.AmzSecurityToken,
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xhttp.AmzAlgorithm,
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xhttp.AmzDate,
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xhttp.AmzExpires,
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xhttp.AmzSignedHeaders,
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xhttp.AmzCredential,
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xhttp.AmzSignature,
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)
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// Add missing query parameters if any provided in the request URL
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for k, v := range req.Form {
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if !defaultSigParams.Contains(k) {
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query[k] = v
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}
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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.Form.Get(xhttp.AmzDate) != query.Get(xhttp.AmzDate) {
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return ErrSignatureDoesNotMatch
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}
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// Verify if expires query is same.
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if req.Form.Get(xhttp.AmzExpires) != query.Get(xhttp.AmzExpires) {
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return ErrSignatureDoesNotMatch
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}
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// Verify if signed headers query is same.
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if req.Form.Get(xhttp.AmzSignedHeaders) != query.Get(xhttp.AmzSignedHeaders) {
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return ErrSignatureDoesNotMatch
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}
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// Verify if credential query is same.
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if req.Form.Get(xhttp.AmzCredential) != query.Get(xhttp.AmzCredential) {
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return ErrSignatureDoesNotMatch
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}
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// Verify if sha256 payload query is same.
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if clntHashedPayload != "" && clntHashedPayload != query.Get(xhttp.AmzContentSha256) {
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return ErrContentSHA256Mismatch
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}
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// Verify if security token is correct.
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if token != "" && subtle.ConstantTimeCompare([]byte(token), []byte(cred.SessionToken)) != 1 {
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return ErrInvalidToken
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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 := getCanonicalRequest(extractedSignedHeaders, hashedPayload, encodedQuery, req.URL.Path, req.Method)
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// Get string to sign from canonical request.
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presignedStringToSign := getStringToSign(presignedCanonicalReq, t, pSignValues.Credential.getScope())
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// Get hmac presigned signing key.
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presignedSigningKey := getSigningKey(cred.SecretKey, pSignValues.Credential.scope.date,
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pSignValues.Credential.scope.region, stype)
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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 !compareSignatureV4(req.Form.Get(xhttp.AmzSignature), newSignature) {
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return ErrSignatureDoesNotMatch
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}
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r.Header.Set("x-amz-signature-age", strconv.FormatInt(UTCNow().Sub(pSignValues.Date).Milliseconds(), 10))
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return ErrNone
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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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//
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// returns ErrNone if signature matches.
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func doesSignatureMatch(hashedPayload string, r *http.Request, region string, stype serviceType) APIErrorCode {
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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(xhttp.Authorization)
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// Parse signature version '4' header.
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signV4Values, err := parseSignV4(v4Auth, region, stype)
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if err != ErrNone {
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return err
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}
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// Extract all the signed headers along with its values.
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extractedSignedHeaders, errCode := extractSignedHeaders(signV4Values.SignedHeaders, r)
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if errCode != ErrNone {
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return errCode
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}
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cred, _, s3Err := checkKeyValid(r, signV4Values.Credential.accessKey)
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if s3Err != ErrNone {
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return s3Err
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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(xhttp.AmzDate); date == "" {
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if date = r.Header.Get(xhttp.Date); date == "" {
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return ErrMissingDateHeader
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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 ErrMalformedDate
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}
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// Query string.
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queryStr := req.Form.Encode()
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// Get canonical request.
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canonicalRequest := getCanonicalRequest(extractedSignedHeaders, hashedPayload, queryStr, req.URL.Path, req.Method)
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// Get string to sign from canonical request.
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stringToSign := getStringToSign(canonicalRequest, t, signV4Values.Credential.getScope())
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// Get hmac signing key.
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signingKey := getSigningKey(cred.SecretKey, signV4Values.Credential.scope.date,
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signV4Values.Credential.scope.region, stype)
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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 !compareSignatureV4(newSignature, signV4Values.Signature) {
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return ErrSignatureDoesNotMatch
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}
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// Return error none.
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return ErrNone
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}
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