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authentication.go
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authentication.go
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/*
* Copyright (c) 2013-2016, Jeremy Bingham (<jeremy@goiardi.gl>)
*
* 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 authentication contains functions used to authenticate requests from
// the signed headers.
package authentication
/* Geez, import all the things why don't you. */
import (
"bytes"
"crypto/sha1"
"encoding/base64"
"fmt"
"io"
"io/ioutil"
"net/http"
"path"
"regexp"
"strconv"
"strings"
"time"
"github.com/ctdk/chefcrypto"
"github.com/ctdk/goiardi/actor"
"github.com/ctdk/goiardi/config"
"github.com/ctdk/goiardi/util"
)
// CheckHeader checks the signed headers sent by the client against the expected
// result assembled from the request headers to verify their authorization.
func CheckHeader(userID string, r *http.Request) util.Gerror {
user, err := actor.GetReqUser(userID)
if err != nil {
gerr := util.Errorf("Failed to authenticate as '%s'. Ensure that your node_name and client key are correct.", userID)
gerr.SetStatus(http.StatusUnauthorized)
return gerr
}
return AuthenticateHeader(user.PublicKey(), config.Config.TimeSlewDur, r)
}
// AuthenticateHeader authenticates the headers against the provided public key.
// In addition, this function supports providing a timeSlew, which is how much
// difference there can be between the host clock and the time in the request
// header.
func AuthenticateHeader(publicKey string, timeSlew time.Duration, r *http.Request) util.Gerror {
// if timeSlew is zero use the default from the config package
if timeSlew == time.Duration(0) {
timeSlew, _ = time.ParseDuration(config.DefaultTimeSlew)
}
contentHash := r.Header.Get("X-OPS-CONTENT-HASH")
if contentHash == "" {
gerr := util.Errorf("no content hash provided")
gerr.SetStatus(http.StatusBadRequest)
return gerr
}
authTimestamp := r.Header.Get("x-ops-timestamp")
if authTimestamp == "" {
gerr := util.Errorf("no timestamp header provided")
gerr.SetStatus(http.StatusBadRequest)
return gerr
}
// check the time stamp w/ allowed slew
tok, terr := checkTimeStamp(authTimestamp, timeSlew)
if !tok {
return terr
}
// Eventually this may be put to some sort of use, but for now just
// make sure that it's there. Presumably eventually it would be used to
// use algorithms other than sha1 for hashing the body, or using a
// different version of the header signing algorithm.
xopssign := r.Header.Get("x-ops-sign")
var apiVer string
if xopssign == "" {
gerr := util.Errorf("missing X-Ops-Sign header")
return gerr
}
re := regexp.MustCompile(`version=(\d+\.\d+)`)
shaRe := regexp.MustCompile(`algorithm=(\w+)`)
if verChk := re.FindStringSubmatch(xopssign); verChk != nil {
apiVer = verChk[1]
if apiVer != "1.0" && apiVer != "1.1" && apiVer != "1.2" {
gerr := util.Errorf("Bad version number '%s' in X-Ops-Header", apiVer)
return gerr
}
} else {
gerr := util.Errorf("malformed version in X-Ops-Header")
return gerr
}
// if algorithm is missing, it uses sha1. Of course, no other
// hashing algorithm is supported yet...
if shaChk := shaRe.FindStringSubmatch(xopssign); shaChk != nil {
if shaChk[1] != "sha1" {
gerr := util.Errorf("Unsupported hashing algorithm '%s' specified in X-Ops-Header", shaChk[1])
return gerr
}
}
chkHash, chkerr := calcBodyHash(r)
if chkerr != nil {
return chkerr
}
if chkHash != contentHash {
gerr := util.Errorf("Content hash did not match hash of request body")
gerr.SetStatus(http.StatusUnauthorized)
return gerr
}
signedHeaders, sherr := assembleSignedHeader(r)
if sherr != nil {
return sherr
}
headToCheck := assembleHeaderToCheck(r, chkHash, apiVer)
if apiVer == "1.2" {
chkerr = checkAuth12Headers(publicKey, r, headToCheck, signedHeaders)
} else {
chkerr = checkAuthHeaders(publicKey, r, headToCheck, signedHeaders)
}
if chkerr != nil {
chkerr.SetStatus(http.StatusUnauthorized)
return chkerr
}
return nil
}
func checkAuth12Headers(publicKey string, r *http.Request, headToCheck, signedHeaders string) util.Gerror {
sig, err := base64.StdEncoding.DecodeString(signedHeaders)
if err != nil {
gerr := util.CastErr(err)
return gerr
}
sigSha := sha1.Sum([]byte(headToCheck))
err = chefcrypto.Auth12HeaderVerify(publicKey, sigSha[:], sig)
if err != nil {
return util.CastErr(err)
}
return nil
}
func checkAuthHeaders(publicKey string, r *http.Request, headToCheck, signedHeaders string) util.Gerror {
decHead, berr := chefcrypto.HeaderDecrypt(publicKey, signedHeaders)
if berr != nil {
gerr := util.Errorf(berr.Error())
gerr.SetStatus(http.StatusUnauthorized)
return gerr
}
if string(decHead) != headToCheck {
gerr := util.Errorf("failed to verify authorization")
gerr.SetStatus(http.StatusUnauthorized)
return gerr
}
return nil
}
// liberated from net/http/httputil
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
func drainBody(b io.ReadCloser) (r1, r2 io.ReadCloser, err error) {
var buf bytes.Buffer
if _, err = buf.ReadFrom(b); err != nil {
return nil, nil, err
}
if err = b.Close(); err != nil {
return nil, nil, err
}
return ioutil.NopCloser(&buf), ioutil.NopCloser(bytes.NewBuffer(buf.Bytes())), nil
}
func assembleSignedHeader(r *http.Request) (string, util.Gerror) {
sHeadStore := make(map[int]string)
authHeader := regexp.MustCompile(`(?i)^X-Ops-Authorization-(\d+)`)
for k := range r.Header {
if c := authHeader.FindStringSubmatch(k); c != nil {
/* Have to put it into a map first, then sort, in case
* the headers don't come out in the right order */
// skipping this error because we shouldn't even be
// able to get here with something that won't be an
// integer. Famous last words, I'm sure.
i, _ := strconv.Atoi(c[1])
sHeadStore[i] = r.Header.Get(k)
}
}
if len(sHeadStore) == 0 {
gerr := util.Errorf("No authentication headers found!")
gerr.SetStatus(http.StatusUnauthorized)
return "", gerr
}
sH := make([]string, len(sHeadStore))
sHlimit := len(sH)
for k, v := range sHeadStore {
if k > sHlimit {
gerr := util.Errorf("malformed authentication headers")
gerr.SetStatus(http.StatusUnauthorized)
return "", gerr
}
sH[k-1] = v
}
signedHeaders := strings.Join(sH, "")
return signedHeaders, nil
}
func checkTimeStamp(timestamp string, slew time.Duration) (bool, util.Gerror) {
timeNow := time.Now().UTC()
timeHeader, terr := time.Parse(time.RFC3339, timestamp)
if terr != nil {
err := util.Errorf(terr.Error())
err.SetStatus(http.StatusUnauthorized)
return false, err
}
tdiff := timeNow.Sub(timeHeader)
// no easy integer based abs function
if tdiff < 0 {
tdiff = -tdiff
}
if tdiff > slew {
err := util.Errorf("Authentication failed. Please check your system's clock.")
err.SetStatus(http.StatusUnauthorized)
return false, err
}
return true, nil
}
func assembleHeaderToCheck(r *http.Request, cHash string, apiVer string) string {
method := r.Method
hashPath := hashStr(path.Clean(r.URL.Path))
timestamp := r.Header.Get("x-ops-timestamp")
userID := r.Header.Get("x-ops-userid")
if apiVer != "1.0" {
userID = hashStr(userID)
}
headStr := fmt.Sprintf("Method:%s\nHashed Path:%s\nX-Ops-Content-Hash:%s\nX-Ops-Timestamp:%s\nX-Ops-UserId:%s", method, hashPath, cHash, timestamp, userID)
return headStr
}
func hashStr(toHash string) string {
h := sha1.New()
io.WriteString(h, toHash)
hashed := base64.StdEncoding.EncodeToString(h.Sum(nil))
return hashed
}
func calcBodyHash(r *http.Request) (string, util.Gerror) {
var bodyStr string
if r.Body == nil {
bodyStr = ""
} else {
var err error
save := r.Body
save, r.Body, err = drainBody(r.Body)
if err != nil {
gerr := util.Errorf("could not copy body")
gerr.SetStatus(http.StatusInternalServerError)
return "", gerr
}
buf := new(bytes.Buffer)
buf.ReadFrom(r.Body)
bodyStr = buf.String()
r.Body = save
}
chkHash := hashStr(bodyStr)
return chkHash, nil
}