minio/auth-handler.go

/*
 * Minio Cloud Storage, (C) 2015 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 main

import (
	"crypto/sha256"
	"encoding/hex"
	"net/http"
	"strings"

	"github.com/minio/minio/pkg/s3/signature4"
)

const (
	signV4Algorithm = "AWS4-HMAC-SHA256"
	jwtAlgorithm    = "Bearer"
)

// Verify if request has JWT.
func isRequestJWT(r *http.Request) bool {
	if _, ok := r.Header["Authorization"]; ok {
		if strings.HasPrefix(r.Header.Get("Authorization"), jwtAlgorithm) {
			return true
		}
	}
	return false
}

// Verify if request has AWS Signature Version '4'.
func isRequestSignatureV4(r *http.Request) bool {
	if _, ok := r.Header["Authorization"]; ok {
		if strings.HasPrefix(r.Header.Get("Authorization"), signV4Algorithm) {
			return true
		}
	}
	return false
}

// Verify if request has AWS Presignature Version '4'.
func isRequestPresignedSignatureV4(r *http.Request) bool {
	if _, ok := r.URL.Query()["X-Amz-Credential"]; ok {
		return true
	}
	return false
}

// Verify if request has AWS Post policy Signature Version '4'.
func isRequestPostPolicySignatureV4(r *http.Request) bool {
	if _, ok := r.Header["Content-Type"]; ok {
		if strings.Contains(r.Header.Get("Content-Type"), "multipart/form-data") && r.Method == "POST" {
			return true
		}
	}
	return false
}

// Verify if incoming request is anonymous.
func isRequestAnonymous(r *http.Request) bool {
	if isRequestJWT(r) || isRequestSignatureV4(r) || isRequestPresignedSignatureV4(r) || isRequestPostPolicySignatureV4(r) {
		return false
	}
	return true
}

// Authorization type.
type authType int

// List of all supported auth types.
const (
	authTypeUnknown authType = iota
	authTypeAnonymous
	authTypePresigned
	authTypePostPolicy
	authTypeSigned
	authTypeJWT
)

// Get request authentication type.
func getRequestAuthType(r *http.Request) authType {
	if isRequestSignatureV4(r) {
		return authTypeSigned
	} else if isRequestPresignedSignatureV4(r) {
		return authTypePresigned
	} else if isRequestJWT(r) {
		return authTypeJWT
	} else if isRequestPostPolicySignatureV4(r) {
		return authTypePostPolicy
	} else if _, ok := r.Header["Authorization"]; !ok {
		return authTypeAnonymous
	}
	return authTypeUnknown
}

// Verify if request has valid AWS Signature Version '4'.
func isReqAuthenticated(sign *signature4.Sign, r *http.Request) (s3Error APIErrorCode) {
	auth := sign.SetHTTPRequestToVerify(r)
	if isRequestSignatureV4(r) {
		dummyPayload := sha256.Sum256([]byte(""))
		ok, err := auth.DoesSignatureMatch(hex.EncodeToString(dummyPayload[:]))
		if err != nil {
			errorIf(err.Trace(), "Signature verification failed.", nil)
			return ErrInternalError
		}
		if !ok {
			return ErrSignatureDoesNotMatch
		}
		return ErrNone
	} else if isRequestPresignedSignatureV4(r) {
		ok, err := auth.DoesPresignedSignatureMatch()
		if err != nil {
			errorIf(err.Trace(), "Presigned signature verification failed.", nil)
			return ErrInternalError
		}
		if !ok {
			return ErrSignatureDoesNotMatch
		}
		return ErrNone
	}
	return ErrAccessDenied
}

// authHandler - handles all the incoming authorization headers and
// validates them if possible.
type authHandler struct {
	handler http.Handler
}

// setAuthHandler to validate authorization header for the incoming request.
func setAuthHandler(h http.Handler) http.Handler {
	return authHandler{h}
}

// handler for validating incoming authorization headers.
func (a authHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	switch getRequestAuthType(r) {
	case authTypeAnonymous, authTypePresigned, authTypeSigned, authTypePostPolicy:
		// Let top level caller validate for anonymous and known
		// signed requests.
		a.handler.ServeHTTP(w, r)
		return
	case authTypeJWT:
		// Validate Authorization header if its valid for JWT request.
		if !isJWTReqAuthenticated(r) {
			w.WriteHeader(http.StatusUnauthorized)
			return
		}
		a.handler.ServeHTTP(w, r)
	default:
		writeErrorResponse(w, r, ErrSignatureVersionNotSupported, r.URL.Path)
		return
	}
}