Signature-V2: use raw resource/query from the request for signature calculation. (#2833)

master
Krishna Srinivas 8 years ago committed by Harshavardhana
parent 740a919e25
commit 95f544657a
  1. 374
      cmd/signature-v2.go
  2. 32
      cmd/test-utils_test.go

@ -17,13 +17,11 @@
package cmd
import (
"bytes"
"crypto/hmac"
"crypto/sha1"
"encoding/base64"
"fmt"
"net/http"
"net/url"
"sort"
"strconv"
"strings"
@ -35,6 +33,29 @@ 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.
var resourceList = []string{
"acl",
"delete",
"lifecycle",
"location",
"logging",
"notification",
"partNumber",
"policy",
"requestPayment",
"torrent",
"uploadId",
"uploads",
"versionId",
"versioning",
"versions",
"website",
}
// TODO add post policy signature.
// doesPresignV2SignatureMatch - Verify query headers with presigned signature
@ -44,59 +65,59 @@ func doesPresignV2SignatureMatch(r *http.Request) APIErrorCode {
// Access credentials.
cred := serverConfig.GetCredential()
// Copy request
req := *r
// url.RawPath will be valid if path has any encoded characters, if not it will
// be empty - in which case we need to consider url.Path (bug in net/http?)
encodedResource := r.URL.RawPath
encodedQuery := r.URL.RawQuery
if encodedResource == "" {
splits := strings.Split(r.URL.Path, "?")
if len(splits) > 0 {
encodedResource = splits[0]
}
}
queries := strings.Split(encodedQuery, "&")
var filteredQueries []string
var gotSignature string
var expires string
var accessKey string
for _, query := range queries {
keyval := strings.Split(query, "=")
switch keyval[0] {
case "AWSAccessKeyId":
accessKey = keyval[1]
case "Signature":
gotSignature = keyval[1]
case "Expires":
expires = keyval[1]
default:
filteredQueries = append(filteredQueries, query)
}
}
// Validate if we do have query params.
if req.URL.Query().Encode() == "" {
if accessKey == "" {
return ErrInvalidQueryParams
}
// Validate if access key id same.
if req.URL.Query().Get("AWSAccessKeyId") != cred.AccessKeyID {
if accessKey != cred.AccessKeyID {
return ErrInvalidAccessKeyID
}
// Parse expires param into its native form.
expired, err := strconv.ParseInt(req.URL.Query().Get("Expires"), 10, 64)
// Make sure the request has not expired.
expiresInt, err := strconv.ParseInt(expires, 10, 64)
if err != nil {
errorIf(err, "Unable to parse expires query param")
return ErrMalformedExpires
}
// Validate if the request has already expired.
if expired < time.Now().UTC().Unix() {
if expiresInt < time.Now().UTC().Unix() {
return ErrExpiredPresignRequest
}
// Save incoming signature to be validated later.
incomingSignature := req.URL.Query().Get("Signature")
// Set the expires header for string to sign.
req.Header.Set("Expires", strconv.FormatInt(expired, 10))
/// Empty out the query params, we only need to validate signature.
query := req.URL.Query()
// Remove all the query params added for signature alone, we need
// a proper URL for string to sign.
query.Del("Expires")
query.Del("AWSAccessKeyId")
query.Del("Signature")
// Query encode whatever is left back to RawQuery.
req.URL.RawQuery = queryEncode(query)
// Get presigned string to sign.
stringToSign := preStringifyHTTPReq(req)
hm := hmac.New(sha1.New, []byte(cred.SecretAccessKey))
hm.Write([]byte(stringToSign))
// Calculate signature and validate.
signature := base64.StdEncoding.EncodeToString(hm.Sum(nil))
if incomingSignature != signature {
expectedSignature := preSignatureV2(r.Method, encodedResource, strings.Join(filteredQueries, "&"), r.Header, expires)
if gotSignature != getURLEncodedName(expectedSignature) {
return ErrSignatureDoesNotMatch
}
// Success.
return ErrNone
}
@ -120,43 +141,111 @@ func doesPresignV2SignatureMatch(r *http.Request) APIErrorCode {
// - 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 doesSignV2Match(r *http.Request) APIErrorCode {
// Access credentials.
cred := serverConfig.GetCredential()
gotAuth := r.Header.Get("Authorization")
if gotAuth == "" {
return ErrAuthHeaderEmpty
}
// Copy request.
req := *r
// url.RawPath will be valid if path has any encoded characters, if not it will
// be empty - in which case we need to consider url.Path (bug in net/http?)
encodedResource := r.URL.RawPath
encodedQuery := r.URL.RawQuery
if encodedResource == "" {
splits := strings.Split(r.URL.Path, "?")
if len(splits) > 0 {
encodedResource = splits[0]
}
}
// Save authorization header.
v2Auth := req.Header.Get("Authorization")
if v2Auth == "" {
return ErrAuthHeaderEmpty
expectedAuth := signatureV2(r.Method, encodedResource, encodedQuery, r.Header)
if gotAuth != expectedAuth {
return ErrSignatureDoesNotMatch
}
// Add date if not present.
if date := req.Header.Get("Date"); date == "" {
if date = req.Header.Get("X-Amz-Date"); date == "" {
return ErrMissingDateHeader
return ErrNone
}
// Return signature-v2 for the presigned request.
func preSignatureV2(method string, encodedResource string, encodedQuery string, headers http.Header, expires string) string {
cred := serverConfig.GetCredential()
stringToSign := presignV2STS(method, encodedResource, encodedQuery, headers, expires)
hm := hmac.New(sha1.New, []byte(cred.SecretAccessKey))
hm.Write([]byte(stringToSign))
signature := base64.StdEncoding.EncodeToString(hm.Sum(nil))
return signature
}
// Calculate HMAC for secretAccessKey.
stringToSign := stringifyHTTPReq(req)
// Return signature-v2 authrization header.
func signatureV2(method string, encodedResource string, encodedQuery string, headers http.Header) string {
cred := serverConfig.GetCredential()
stringToSign := signV2STS(method, encodedResource, encodedQuery, headers)
hm := hmac.New(sha1.New, []byte(cred.SecretAccessKey))
hm.Write([]byte(stringToSign))
signature := base64.StdEncoding.EncodeToString(hm.Sum(nil))
return fmt.Sprintf("%s %s:%s", signV2Algorithm, cred.AccessKeyID, signature)
}
// Prepare auth header.
authHeader := new(bytes.Buffer)
authHeader.WriteString(fmt.Sprintf("%s %s:", signV2Algorithm, cred.AccessKeyID))
encoder := base64.NewEncoder(base64.StdEncoding, authHeader)
encoder.Write(hm.Sum(nil))
encoder.Close()
// 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")
}
// Verify if signature match.
if authHeader.String() != v2Auth {
return ErrSignatureDoesNotMatch
// Return canonical resource string.
func canonicalizedResourceV2(encodedPath string, 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)
}
if len(canonicalQueries) == 0 {
return encodedPath
}
// the queries will be already sorted as resourceList is sorted.
return encodedPath + "?" + strings.Join(canonicalQueries, "&")
}
return ErrNone
// Return string to sign for authz header calculation.
func signV2STS(method string, encodedResource string, encodedQuery string, headers http.Header) string {
canonicalHeaders := canonicalizedAmzHeadersV2(headers)
if len(canonicalHeaders) > 0 {
canonicalHeaders += "\n"
}
// From the Amazon docs:
@ -164,27 +253,25 @@ func doesSignV2Match(r *http.Request) APIErrorCode {
// StringToSign = HTTP-Verb + "\n" +
// Content-Md5 + "\n" +
// Content-Type + "\n" +
// Expires + "\n" +
// Date + "\n" +
// CanonicalizedProtocolHeaders +
// CanonicalizedResource;
func preStringifyHTTPReq(req http.Request) string {
buf := new(bytes.Buffer)
// Write standard headers.
writePreSignV2Headers(buf, req)
// Write canonicalized protocol headers if any.
writeCanonicalizedHeaders(buf, req)
// Write canonicalized Query resources if any.
isPreSign := true
writeCanonicalizedResource(buf, req, isPreSign)
return buf.String()
stringToSign := strings.Join([]string{
method,
headers.Get("Content-MD5"),
headers.Get("Content-Type"),
headers.Get("Date"),
canonicalHeaders,
}, "\n") + canonicalizedResourceV2(encodedResource, encodedQuery)
return stringToSign
}
// writePreSignV2Headers - write preSign v2 required headers.
func writePreSignV2Headers(buf *bytes.Buffer, req http.Request) {
buf.WriteString(req.Method + "\n")
buf.WriteString(req.Header.Get("Content-Md5") + "\n")
buf.WriteString(req.Header.Get("Content-Type") + "\n")
buf.WriteString(req.Header.Get("Expires") + "\n")
// Return string to sign for pre-sign signature calculation.
func presignV2STS(method string, encodedResource string, encodedQuery string, headers http.Header, expires string) string {
canonicalHeaders := canonicalizedAmzHeadersV2(headers)
if len(canonicalHeaders) > 0 {
canonicalHeaders += "\n"
}
// From the Amazon docs:
@ -192,128 +279,15 @@ func writePreSignV2Headers(buf *bytes.Buffer, req http.Request) {
// StringToSign = HTTP-Verb + "\n" +
// Content-Md5 + "\n" +
// Content-Type + "\n" +
// Date + "\n" +
// Expires + "\n" +
// CanonicalizedProtocolHeaders +
// CanonicalizedResource;
func stringifyHTTPReq(req http.Request) string {
buf := new(bytes.Buffer)
// Write standard headers.
writeSignV2Headers(buf, req)
// Write canonicalized protocol headers if any.
writeCanonicalizedHeaders(buf, req)
// Write canonicalized Query resources if any.
isPreSign := false
writeCanonicalizedResource(buf, req, isPreSign)
return buf.String()
}
// writeSignV2Headers - write signV2 required headers.
func writeSignV2Headers(buf *bytes.Buffer, req http.Request) {
buf.WriteString(req.Method + "\n")
buf.WriteString(req.Header.Get("Content-Md5") + "\n")
buf.WriteString(req.Header.Get("Content-Type") + "\n")
buf.WriteString(req.Header.Get("Date") + "\n")
}
// writeCanonicalizedHeaders - write canonicalized headers.
func writeCanonicalizedHeaders(buf *bytes.Buffer, req http.Request) {
var protoHeaders []string
vals := make(map[string][]string)
for k, vv := range req.Header {
// All the AMZ headers should be lowercase
lk := strings.ToLower(k)
if strings.HasPrefix(lk, "x-amz") {
protoHeaders = append(protoHeaders, lk)
vals[lk] = vv
}
}
sort.Strings(protoHeaders)
for _, k := range protoHeaders {
buf.WriteString(k)
buf.WriteByte(':')
for idx, v := range vals[k] {
if idx > 0 {
buf.WriteByte(',')
}
if strings.Contains(v, "\n") {
// TODO: "Unfold" long headers that
// span multiple lines (as allowed by
// RFC 2616, section 4.2) by replacing
// the folding white-space (including
// new-line) by a single space.
buf.WriteString(v)
} else {
buf.WriteString(v)
}
}
buf.WriteByte('\n')
}
}
// The following list is already sorted and should always be, otherwise we could
// have signature-related issues
var resourceList = []string{
"acl",
"delete",
"location",
"logging",
"notification",
"partNumber",
"policy",
"requestPayment",
"torrent",
"uploadId",
"uploads",
"versionId",
"versioning",
"versions",
"website",
}
// From the Amazon docs:
//
// CanonicalizedResource = [ "/" + Bucket ] +
// <HTTP-Request-URI, from the protocol name up to the query string> +
// [ sub-resource, if present. For example "?acl", "?location", "?logging", or "?torrent"];
func writeCanonicalizedResource(buf *bytes.Buffer, req http.Request, isPreSign bool) {
// Save request URL.
requestURL := req.URL
// Get encoded URL path.
path := getURLEncodedName(requestURL.Path)
if isPreSign {
// Get encoded URL path.
if len(requestURL.Query()) > 0 {
// Keep the usual queries unescaped for string to sign.
query, _ := url.QueryUnescape(queryEncode(requestURL.Query()))
path = path + "?" + query
}
buf.WriteString(path)
return
}
buf.WriteString(path)
if requestURL.RawQuery != "" {
var n int
vals, _ := url.ParseQuery(requestURL.RawQuery)
// Verify if any sub resource queries are present, if yes
// canonicallize them.
for _, resource := range resourceList {
if vv, ok := vals[resource]; ok && len(vv) > 0 {
n++
// First element
switch n {
case 1:
buf.WriteByte('?')
// The rest
default:
buf.WriteByte('&')
}
buf.WriteString(resource)
// Request parameters
if len(vv[0]) > 0 {
buf.WriteByte('=')
buf.WriteString(strings.Replace(url.QueryEscape(vv[0]), "+", "%20", -1))
}
}
}
}
stringToSign := strings.Join([]string{
method,
headers.Get("Content-MD5"),
headers.Get("Content-Type"),
expires,
canonicalHeaders,
}, "\n") + canonicalizedResourceV2(encodedResource, encodedQuery)
return stringToSign
}

@ -489,12 +489,25 @@ func preSignV2(req *http.Request, accessKeyID, secretAccessKey string, expires i
epochExpires := d.Unix() + expires
// Add expires header if not present.
if expiresStr := req.Header.Get("Expires"); expiresStr == "" {
req.Header.Set("Expires", strconv.FormatInt(epochExpires, 10))
expiresStr := req.Header.Get("Expires")
if expiresStr == "" {
expiresStr = strconv.FormatInt(epochExpires, 10)
req.Header.Set("Expires", expiresStr)
}
// url.RawPath will be valid if path has any encoded characters, if not it will
// be empty - in which case we need to consider url.Path (bug in net/http?)
encodedResource := req.URL.RawPath
encodedQuery := req.URL.RawQuery
if encodedResource == "" {
splits := strings.Split(req.URL.Path, "?")
if len(splits) > 0 {
encodedResource = splits[0]
}
}
// Get presigned string to sign.
stringToSign := preStringifyHTTPReq(*req)
stringToSign := presignV2STS(req.Method, encodedResource, encodedQuery, req.Header, expiresStr)
hm := hmac.New(sha1.New, []byte(secretAccessKey))
hm.Write([]byte(stringToSign))
@ -527,8 +540,19 @@ func signRequestV2(req *http.Request, accessKey, secretKey string) error {
req.Header.Set("Date", d.Format(http.TimeFormat))
}
// url.RawPath will be valid if path has any encoded characters, if not it will
// be empty - in which case we need to consider url.Path (bug in net/http?)
encodedResource := req.URL.RawPath
encodedQuery := req.URL.RawQuery
if encodedResource == "" {
splits := strings.Split(req.URL.Path, "?")
if len(splits) > 0 {
encodedResource = splits[0]
}
}
// Calculate HMAC for secretAccessKey.
stringToSign := stringifyHTTPReq(*req)
stringToSign := signV2STS(req.Method, encodedResource, encodedQuery, req.Header)
hm := hmac.New(sha1.New, []byte(secretKey))
hm.Write([]byte(stringToSign))

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