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minio/cmd/signature-v2.go

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/*
* Minio Cloud Storage, (C) 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
import (
"crypto/hmac"
"crypto/sha1"
"crypto/subtle"
"encoding/base64"
"fmt"
"net/http"
"net/url"
"sort"
"strconv"
"strings"
"github.com/minio/minio/pkg/auth"
)
// Signature and API related constants.
const (
signV2Algorithm = "AWS"
)
// AWS S3 Signature V2 calculation rule is give here:
// http://docs.aws.amazon.com/AmazonS3/latest/dev/RESTAuthentication.html#RESTAuthenticationStringToSign
// Whitelist resource list that will be used in query string for signature-V2 calculation.
// The list should be alphabetically sorted
var resourceList = []string{
"acl",
"delete",
"lifecycle",
"location",
"logging",
"notification",
"partNumber",
"policy",
"requestPayment",
"response-cache-control",
"response-content-disposition",
"response-content-encoding",
"response-content-language",
"response-content-type",
"response-expires",
"torrent",
"uploadId",
"uploads",
"versionId",
"versioning",
"versions",
"website",
}
func doesPolicySignatureV2Match(formValues http.Header) APIErrorCode {
cred := globalServerConfig.GetCredential()
accessKey := formValues.Get("AWSAccessKeyId")
cred, _, s3Err := checkKeyValid(accessKey)
if s3Err != ErrNone {
return s3Err
}
policy := formValues.Get("Policy")
signature := formValues.Get("Signature")
if !compareSignatureV2(signature, calculateSignatureV2(policy, cred.SecretKey)) {
return ErrSignatureDoesNotMatch
}
return ErrNone
}
// Escape encodedQuery string into unescaped list of query params, returns error
// if any while unescaping the values.
func unescapeQueries(encodedQuery string) (unescapedQueries []string, err error) {
for _, query := range strings.Split(encodedQuery, "&") {
var unescapedQuery string
unescapedQuery, err = url.QueryUnescape(query)
if err != nil {
return nil, err
}
unescapedQueries = append(unescapedQueries, unescapedQuery)
}
return unescapedQueries, nil
}
// doesPresignV2SignatureMatch - Verify query headers with presigned signature
// - http://docs.aws.amazon.com/AmazonS3/latest/dev/RESTAuthentication.html#RESTAuthenticationQueryStringAuth
// returns ErrNone if matches. S3 errors otherwise.
func doesPresignV2SignatureMatch(r *http.Request) APIErrorCode {
// Access credentials.
cred := globalServerConfig.GetCredential()
// r.RequestURI will have raw encoded URI as sent by the client.
tokens := strings.SplitN(r.RequestURI, "?", 2)
encodedResource := tokens[0]
encodedQuery := ""
if len(tokens) == 2 {
encodedQuery = tokens[1]
}
var (
filteredQueries []string
gotSignature string
expires string
accessKey string
err error
)
var unescapedQueries []string
unescapedQueries, err = unescapeQueries(encodedQuery)
if err != nil {
return ErrInvalidQueryParams
}
// Extract the necessary values from presigned query, construct a list of new filtered queries.
for _, query := range unescapedQueries {
keyval := strings.SplitN(query, "=", 2)
if len(keyval) != 2 {
return ErrInvalidQueryParams
}
switch keyval[0] {
case "AWSAccessKeyId":
accessKey = keyval[1]
case "Signature":
gotSignature = keyval[1]
case "Expires":
expires = keyval[1]
default:
filteredQueries = append(filteredQueries, query)
}
}
// Invalid values returns error.
if accessKey == "" || gotSignature == "" || expires == "" {
return ErrInvalidQueryParams
}
cred, _, s3Err := checkKeyValid(accessKey)
if s3Err != ErrNone {
return s3Err
}
// Make sure the request has not expired.
expiresInt, err := strconv.ParseInt(expires, 10, 64)
if err != nil {
return ErrMalformedExpires
}
// Check if the presigned URL has expired.
if expiresInt < UTCNow().Unix() {
return ErrExpiredPresignRequest
}
encodedResource, err = getResource(encodedResource, r.Host, globalDomainNames)
if err != nil {
return ErrInvalidRequest
}
expectedSignature := preSignatureV2(cred, r.Method, encodedResource, strings.Join(filteredQueries, "&"), r.Header, expires)
if !compareSignatureV2(gotSignature, expectedSignature) {
return ErrSignatureDoesNotMatch
}
return ErrNone
}
func getReqAccessKeyV2(r *http.Request) (auth.Credentials, bool, APIErrorCode) {
if accessKey := r.URL.Query().Get("AWSAccessKeyId"); accessKey != "" {
return checkKeyValid(accessKey)
}
// below is V2 Signed Auth header format, splitting on `space` (after the `AWS` string).
// Authorization = "AWS" + " " + AWSAccessKeyId + ":" + Signature
authFields := strings.Split(r.Header.Get("Authorization"), " ")
if len(authFields) != 2 {
return auth.Credentials{}, false, ErrMissingFields
}
// Then will be splitting on ":", this will seprate `AWSAccessKeyId` and `Signature` string.
keySignFields := strings.Split(strings.TrimSpace(authFields[1]), ":")
if len(keySignFields) != 2 {
return auth.Credentials{}, false, ErrMissingFields
}
return checkKeyValid(keySignFields[0])
}
// Authorization = "AWS" + " " + AWSAccessKeyId + ":" + Signature;
// Signature = Base64( HMAC-SHA1( YourSecretKey, UTF-8-Encoding-Of( StringToSign ) ) );
//
// StringToSign = HTTP-Verb + "\n" +
// Content-Md5 + "\n" +
// Content-Type + "\n" +
// Date + "\n" +
// CanonicalizedProtocolHeaders +
// CanonicalizedResource;
//
// CanonicalizedResource = [ "/" + Bucket ] +
// <HTTP-Request-URI, from the protocol name up to the query string> +
// [ subresource, if present. For example "?acl", "?location", "?logging", or "?torrent"];
//
// CanonicalizedProtocolHeaders = <described below>
// doesSignV2Match - Verify authorization header with calculated header in accordance with
// - http://docs.aws.amazon.com/AmazonS3/latest/dev/auth-request-sig-v2.html
// returns true if matches, false otherwise. if error is not nil then it is always false
func validateV2AuthHeader(r *http.Request) (auth.Credentials, APIErrorCode) {
var cred auth.Credentials
v2Auth := r.Header.Get("Authorization")
if v2Auth == "" {
return cred, ErrAuthHeaderEmpty
}
// Verify if the header algorithm is supported or not.
if !strings.HasPrefix(v2Auth, signV2Algorithm) {
return cred, ErrSignatureVersionNotSupported
}
cred, _, apiErr := getReqAccessKeyV2(r)
if apiErr != ErrNone {
return cred, apiErr
}
return cred, ErrNone
}
func doesSignV2Match(r *http.Request) APIErrorCode {
v2Auth := r.Header.Get("Authorization")
cred, apiError := validateV2AuthHeader(r)
if apiError != ErrNone {
return apiError
}
// r.RequestURI will have raw encoded URI as sent by the client.
tokens := strings.SplitN(r.RequestURI, "?", 2)
encodedResource := tokens[0]
encodedQuery := ""
if len(tokens) == 2 {
encodedQuery = tokens[1]
}
unescapedQueries, err := unescapeQueries(encodedQuery)
if err != nil {
return ErrInvalidQueryParams
}
encodedResource, err = getResource(encodedResource, r.Host, globalDomainNames)
if err != nil {
return ErrInvalidRequest
}
prefix := fmt.Sprintf("%s %s:", signV2Algorithm, cred.AccessKey)
if !strings.HasPrefix(v2Auth, prefix) {
return ErrSignatureDoesNotMatch
}
v2Auth = v2Auth[len(prefix):]
expectedAuth := signatureV2(cred, r.Method, encodedResource, strings.Join(unescapedQueries, "&"), r.Header)
if !compareSignatureV2(v2Auth, expectedAuth) {
return ErrSignatureDoesNotMatch
}
return ErrNone
}
func calculateSignatureV2(stringToSign string, secret string) string {
hm := hmac.New(sha1.New, []byte(secret))
hm.Write([]byte(stringToSign))
return base64.StdEncoding.EncodeToString(hm.Sum(nil))
}
// Return signature-v2 for the presigned request.
func preSignatureV2(cred auth.Credentials, method string, encodedResource string, encodedQuery string, headers http.Header, expires string) string {
stringToSign := getStringToSignV2(method, encodedResource, encodedQuery, headers, expires)
return calculateSignatureV2(stringToSign, cred.SecretKey)
}
// Return the signature v2 of a given request.
func signatureV2(cred auth.Credentials, method string, encodedResource string, encodedQuery string, headers http.Header) string {
stringToSign := getStringToSignV2(method, encodedResource, encodedQuery, headers, "")
signature := calculateSignatureV2(stringToSign, cred.SecretKey)
return signature
}
// compareSignatureV2 returns true if and only if both signatures
// are equal. The signatures are expected to be base64 encoded strings
// according to the AWS S3 signature V2 spec.
func compareSignatureV2(sig1, sig2 string) bool {
// Decode signature string to binary byte-sequence representation is required
// as Base64 encoding of a value is not unique:
// For example "aGVsbG8=" and "aGVsbG8=\r" will result in the same byte slice.
signature1, err := base64.StdEncoding.DecodeString(sig1)
if err != nil {
return false
}
signature2, err := base64.StdEncoding.DecodeString(sig2)
if err != nil {
return false
}
return subtle.ConstantTimeCompare(signature1, signature2) == 1
}
// Return canonical headers.
func canonicalizedAmzHeadersV2(headers http.Header) string {
var keys []string
keyval := make(map[string]string)
for key := range headers {
lkey := strings.ToLower(key)
if !strings.HasPrefix(lkey, "x-amz-") {
continue
}
keys = append(keys, lkey)
keyval[lkey] = strings.Join(headers[key], ",")
}
sort.Strings(keys)
var canonicalHeaders []string
for _, key := range keys {
canonicalHeaders = append(canonicalHeaders, key+":"+keyval[key])
}
return strings.Join(canonicalHeaders, "\n")
}
// Return canonical resource string.
func canonicalizedResourceV2(encodedResource, encodedQuery string) string {
queries := strings.Split(encodedQuery, "&")
keyval := make(map[string]string)
for _, query := range queries {
key := query
val := ""
index := strings.Index(query, "=")
if index != -1 {
key = query[:index]
val = query[index+1:]
}
keyval[key] = val
}
var canonicalQueries []string
for _, key := range resourceList {
val, ok := keyval[key]
if !ok {
continue
}
if val == "" {
canonicalQueries = append(canonicalQueries, key)
continue
}
canonicalQueries = append(canonicalQueries, key+"="+val)
}
// The queries will be already sorted as resourceList is sorted, if canonicalQueries
// is empty strings.Join returns empty.
canonicalQuery := strings.Join(canonicalQueries, "&")
if canonicalQuery != "" {
return encodedResource + "?" + canonicalQuery
}
return encodedResource
}
// Return string to sign under two different conditions.
// - if expires string is set then string to sign includes date instead of the Date header.
// - if expires string is empty then string to sign includes date header instead.
func getStringToSignV2(method string, encodedResource, encodedQuery string, headers http.Header, expires string) string {
canonicalHeaders := canonicalizedAmzHeadersV2(headers)
if len(canonicalHeaders) > 0 {
canonicalHeaders += "\n"
}
date := expires // Date is set to expires date for presign operations.
if date == "" {
// If expires date is empty then request header Date is used.
date = headers.Get("Date")
}
// From the Amazon docs:
//
// StringToSign = HTTP-Verb + "\n" +
// Content-Md5 + "\n" +
// Content-Type + "\n" +
// Date/Expires + "\n" +
// CanonicalizedProtocolHeaders +
// CanonicalizedResource;
stringToSign := strings.Join([]string{
method,
headers.Get("Content-MD5"),
headers.Get("Content-Type"),
date,
canonicalHeaders,
}, "\n")
return stringToSign + canonicalizedResourceV2(encodedResource, encodedQuery)
}