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372 lines
12 KiB
372 lines
12 KiB
/*
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* Minio Cloud Storage, (C) 2015 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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package fs
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import (
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"bytes"
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"crypto/hmac"
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"encoding/hex"
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"net/http"
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"net/url"
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"regexp"
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"sort"
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"strconv"
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"strings"
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"time"
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"unicode/utf8"
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"github.com/minio/minio-xl/pkg/crypto/sha256"
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"github.com/minio/minio-xl/pkg/probe"
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)
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// Signature - local variables
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type Signature struct {
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AccessKeyID string
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SecretAccessKey string
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Region string
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Presigned bool
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PresignedPolicy string
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SignedHeaders []string
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Signature string
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Request *http.Request
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}
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const (
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authHeaderPrefix = "AWS4-HMAC-SHA256"
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iso8601Format = "20060102T150405Z"
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yyyymmdd = "20060102"
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)
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// sumHMAC calculate hmac between two input byte array
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func sumHMAC(key []byte, data []byte) []byte {
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hash := hmac.New(sha256.New, key)
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hash.Write(data)
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return hash.Sum(nil)
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}
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// getURLEncodedName encode the strings from UTF-8 byte representations to HTML hex escape sequences
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//
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// This is necessary since regular url.Parse() and url.Encode() functions do not support UTF-8
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// non english characters cannot be parsed due to the nature in which url.Encode() is written
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//
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// This function on the other hand is a direct replacement for url.Encode() technique to support
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// pretty much every UTF-8 character.
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func getURLEncodedName(name string) string {
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// if object matches reserved string, no need to encode them
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reservedNames := regexp.MustCompile("^[a-zA-Z0-9-_.~/]+$")
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if reservedNames.MatchString(name) {
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return name
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}
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var encodedName string
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for _, s := range name {
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if 'A' <= s && s <= 'Z' || 'a' <= s && s <= 'z' || '0' <= s && s <= '9' { // §2.3 Unreserved characters (mark)
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encodedName = encodedName + string(s)
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continue
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}
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switch s {
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case '-', '_', '.', '~', '/': // §2.3 Unreserved characters (mark)
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encodedName = encodedName + string(s)
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continue
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default:
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len := utf8.RuneLen(s)
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if len < 0 {
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return name
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}
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u := make([]byte, len)
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utf8.EncodeRune(u, s)
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for _, r := range u {
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hex := hex.EncodeToString([]byte{r})
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encodedName = encodedName + "%" + strings.ToUpper(hex)
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}
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}
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}
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return encodedName
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}
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// getCanonicalHeaders generate a list of request headers with their values
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func (r Signature) getCanonicalHeaders(signedHeaders map[string][]string) string {
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var headers []string
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vals := make(map[string][]string)
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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(r.Request.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 (r Signature) getSignedHeaders(signedHeaders map[string][]string) 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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// extractSignedHeaders extract signed headers from Authorization header
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func (r Signature) extractSignedHeaders() map[string][]string {
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extractedSignedHeadersMap := make(map[string][]string)
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for _, header := range r.SignedHeaders {
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val, ok := r.Request.Header[http.CanonicalHeaderKey(header)]
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if !ok {
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// Golang http server strips off 'Expect' header, if the
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// client sent this as part of signed headers we need to
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// handle otherwise we would see a signature mismatch.
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// `aws-cli` sets this as part of signed headers which is
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// a bad idea since servers trying to implement AWS
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// Signature version '4' will all encounter this issue.
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//
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// According to
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// http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.20
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// Expect header is always of form:
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//
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// Expect = "Expect" ":" 1#expectation
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// expectation = "100-continue" | expectation-extension
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//
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// So it safe to assume that '100-continue' is what would
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// be sent, for the time being keep this work around.
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// Adding a *TODO* to remove this later when Golang server
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// doesn't filter out the 'Expect' header.
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if header == "expect" {
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extractedSignedHeadersMap[header] = []string{"100-continue"}
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}
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// if not found continue, we will fail later
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continue
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}
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extractedSignedHeadersMap[header] = val
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}
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return extractedSignedHeadersMap
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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 (r *Signature) getCanonicalRequest() string {
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payload := r.Request.Header.Get(http.CanonicalHeaderKey("x-amz-content-sha256"))
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r.Request.URL.RawQuery = strings.Replace(r.Request.URL.Query().Encode(), "+", "%20", -1)
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encodedPath := getURLEncodedName(r.Request.URL.Path)
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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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r.Request.Method,
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encodedPath,
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r.Request.URL.RawQuery,
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r.getCanonicalHeaders(r.extractSignedHeaders()),
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r.getSignedHeaders(r.extractSignedHeaders()),
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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 (r Signature) getPresignedCanonicalRequest(presignedQuery string) string {
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rawQuery := strings.Replace(presignedQuery, "+", "%20", -1)
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encodedPath := getURLEncodedName(r.Request.URL.Path)
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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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r.Request.Method,
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encodedPath,
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rawQuery,
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r.getCanonicalHeaders(r.extractSignedHeaders()),
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r.getSignedHeaders(r.extractSignedHeaders()),
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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 (r Signature) getScope(t time.Time) string {
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scope := strings.Join([]string{
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t.Format(yyyymmdd),
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r.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 (r Signature) getStringToSign(canonicalRequest string, t time.Time) string {
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stringToSign := authHeaderPrefix + "\n" + t.Format(iso8601Format) + "\n"
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stringToSign = stringToSign + r.getScope(t) + "\n"
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stringToSign = stringToSign + hex.EncodeToString(sha256.Sum256([]byte(canonicalRequest)))
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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 (r Signature) getSigningKey(t time.Time) []byte {
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secret := r.SecretAccessKey
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date := sumHMAC([]byte("AWS4"+secret), []byte(t.Format(yyyymmdd)))
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region := sumHMAC(date, []byte(r.Region))
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service := sumHMAC(region, []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 (r Signature) 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 (r *Signature) DoesPolicySignatureMatch(date string) (bool, *probe.Error) {
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t, err := time.Parse(iso8601Format, date)
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if err != nil {
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return false, probe.NewError(err)
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}
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signingKey := r.getSigningKey(t)
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stringToSign := string(r.PresignedPolicy)
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newSignature := r.getSignature(signingKey, stringToSign)
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if newSignature != r.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 (r *Signature) DoesPresignedSignatureMatch() (bool, *probe.Error) {
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query := make(url.Values)
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query.Set("X-Amz-Algorithm", authHeaderPrefix)
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var date string
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if date = r.Request.URL.Query().Get("X-Amz-Date"); date == "" {
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return false, probe.NewError(MissingDateHeader{})
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}
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t, err := time.Parse(iso8601Format, date)
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if err != nil {
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return false, probe.NewError(err)
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}
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if _, ok := r.Request.URL.Query()["X-Amz-Expires"]; !ok {
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return false, probe.NewError(MissingExpiresQuery{})
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}
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expireSeconds, err := strconv.Atoi(r.Request.URL.Query().Get("X-Amz-Expires"))
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if err != nil {
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return false, probe.NewError(err)
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}
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if time.Now().UTC().Sub(t) > time.Duration(expireSeconds)*time.Second {
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return false, probe.NewError(ExpiredPresignedRequest{})
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}
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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", r.getSignedHeaders(r.extractSignedHeaders()))
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query.Set("X-Amz-Credential", r.AccessKeyID+"/"+r.getScope(t))
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// Save other headers available in the request parameters.
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for k, v := range r.Request.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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encodedQuery := query.Encode()
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// Verify if date query is same.
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if r.Request.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 r.Request.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 r.Request.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 r.Request.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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newSignature := r.getSignature(r.getSigningKey(t), r.getStringToSign(r.getPresignedCanonicalRequest(encodedQuery), t))
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if r.Request.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 (r *Signature) DoesSignatureMatch(hashedPayload string) (bool, *probe.Error) {
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// set new calculated payload
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r.Request.Header.Set("X-Amz-Content-Sha256", hashedPayload)
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// Add date if not present throw error
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var date string
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if date = r.Request.Header.Get(http.CanonicalHeaderKey("x-amz-date")); date == "" {
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if date = r.Request.Header.Get("Date"); date == "" {
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return false, probe.NewError(MissingDateHeader{})
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}
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}
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t, err := time.Parse(iso8601Format, date)
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if err != nil {
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return false, probe.NewError(err)
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}
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canonicalRequest := r.getCanonicalRequest()
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stringToSign := r.getStringToSign(canonicalRequest, t)
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signingKey := r.getSigningKey(t)
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newSignature := r.getSignature(signingKey, stringToSign)
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if newSignature != r.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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