Daniel Martí 1c06e8705e all: make use of oauth.Token.ExpiresIn
With https://go.dev/issue/61417 implemented, we can use the token type
directly to unmarshal the JSON fields for the wire format.

While here, remove all uses of the deprecated ioutil package
as suggested by gopls while making these changes.

Change-Id: I79d82374643007a21b5b3d9a8117bed81273eca5
Reviewed-on: https://go-review.googlesource.com/c/oauth2/+/614415
Reviewed-by: Sean Liao <sean@liao.dev>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
2025-04-17 01:27:37 -07:00

577 lines
16 KiB
Go

// Copyright 2021 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.
package externalaccount
import (
"bytes"
"context"
"crypto/hmac"
"crypto/sha256"
"encoding/hex"
"encoding/json"
"errors"
"fmt"
"io"
"net/http"
"net/url"
"os"
"path"
"sort"
"strings"
"time"
"golang.org/x/oauth2"
)
// AwsSecurityCredentials models AWS security credentials.
type AwsSecurityCredentials struct {
// AccessKeyID is the AWS Access Key ID - Required.
AccessKeyID string `json:"AccessKeyID"`
// SecretAccessKey is the AWS Secret Access Key - Required.
SecretAccessKey string `json:"SecretAccessKey"`
// SessionToken is the AWS Session token. This should be provided for temporary AWS security credentials - Optional.
SessionToken string `json:"Token"`
}
// awsRequestSigner is a utility class to sign http requests using a AWS V4 signature.
type awsRequestSigner struct {
RegionName string
AwsSecurityCredentials *AwsSecurityCredentials
}
// getenv aliases os.Getenv for testing
var getenv = os.Getenv
const (
defaultRegionalCredentialVerificationUrl = "https://sts.{region}.amazonaws.com?Action=GetCallerIdentity&Version=2011-06-15"
// AWS Signature Version 4 signing algorithm identifier.
awsAlgorithm = "AWS4-HMAC-SHA256"
// The termination string for the AWS credential scope value as defined in
// https://docs.aws.amazon.com/general/latest/gr/sigv4-create-string-to-sign.html
awsRequestType = "aws4_request"
// The AWS authorization header name for the security session token if available.
awsSecurityTokenHeader = "x-amz-security-token"
// The name of the header containing the session token for metadata endpoint calls
awsIMDSv2SessionTokenHeader = "X-aws-ec2-metadata-token"
awsIMDSv2SessionTtlHeader = "X-aws-ec2-metadata-token-ttl-seconds"
awsIMDSv2SessionTtl = "300"
// The AWS authorization header name for the auto-generated date.
awsDateHeader = "x-amz-date"
// Supported AWS configuration environment variables.
awsAccessKeyId = "AWS_ACCESS_KEY_ID"
awsDefaultRegion = "AWS_DEFAULT_REGION"
awsRegion = "AWS_REGION"
awsSecretAccessKey = "AWS_SECRET_ACCESS_KEY"
awsSessionToken = "AWS_SESSION_TOKEN"
awsTimeFormatLong = "20060102T150405Z"
awsTimeFormatShort = "20060102"
)
func getSha256(input []byte) (string, error) {
hash := sha256.New()
if _, err := hash.Write(input); err != nil {
return "", err
}
return hex.EncodeToString(hash.Sum(nil)), nil
}
func getHmacSha256(key, input []byte) ([]byte, error) {
hash := hmac.New(sha256.New, key)
if _, err := hash.Write(input); err != nil {
return nil, err
}
return hash.Sum(nil), nil
}
func cloneRequest(r *http.Request) *http.Request {
r2 := new(http.Request)
*r2 = *r
if r.Header != nil {
r2.Header = make(http.Header, len(r.Header))
// Find total number of values.
headerCount := 0
for _, headerValues := range r.Header {
headerCount += len(headerValues)
}
copiedHeaders := make([]string, headerCount) // shared backing array for headers' values
for headerKey, headerValues := range r.Header {
headerCount = copy(copiedHeaders, headerValues)
r2.Header[headerKey] = copiedHeaders[:headerCount:headerCount]
copiedHeaders = copiedHeaders[headerCount:]
}
}
return r2
}
func canonicalPath(req *http.Request) string {
result := req.URL.EscapedPath()
if result == "" {
return "/"
}
return path.Clean(result)
}
func canonicalQuery(req *http.Request) string {
queryValues := req.URL.Query()
for queryKey := range queryValues {
sort.Strings(queryValues[queryKey])
}
return queryValues.Encode()
}
func canonicalHeaders(req *http.Request) (string, string) {
// Header keys need to be sorted alphabetically.
var headers []string
lowerCaseHeaders := make(http.Header)
for k, v := range req.Header {
k := strings.ToLower(k)
if _, ok := lowerCaseHeaders[k]; ok {
// include additional values
lowerCaseHeaders[k] = append(lowerCaseHeaders[k], v...)
} else {
headers = append(headers, k)
lowerCaseHeaders[k] = v
}
}
sort.Strings(headers)
var fullHeaders bytes.Buffer
for _, header := range headers {
headerValue := strings.Join(lowerCaseHeaders[header], ",")
fullHeaders.WriteString(header)
fullHeaders.WriteRune(':')
fullHeaders.WriteString(headerValue)
fullHeaders.WriteRune('\n')
}
return strings.Join(headers, ";"), fullHeaders.String()
}
func requestDataHash(req *http.Request) (string, error) {
var requestData []byte
if req.Body != nil {
requestBody, err := req.GetBody()
if err != nil {
return "", err
}
defer requestBody.Close()
requestData, err = io.ReadAll(io.LimitReader(requestBody, 1<<20))
if err != nil {
return "", err
}
}
return getSha256(requestData)
}
func requestHost(req *http.Request) string {
if req.Host != "" {
return req.Host
}
return req.URL.Host
}
func canonicalRequest(req *http.Request, canonicalHeaderColumns, canonicalHeaderData string) (string, error) {
dataHash, err := requestDataHash(req)
if err != nil {
return "", err
}
return fmt.Sprintf("%s\n%s\n%s\n%s\n%s\n%s", req.Method, canonicalPath(req), canonicalQuery(req), canonicalHeaderData, canonicalHeaderColumns, dataHash), nil
}
// SignRequest adds the appropriate headers to an http.Request
// or returns an error if something prevented this.
func (rs *awsRequestSigner) SignRequest(req *http.Request) error {
signedRequest := cloneRequest(req)
timestamp := now()
signedRequest.Header.Add("host", requestHost(req))
if rs.AwsSecurityCredentials.SessionToken != "" {
signedRequest.Header.Add(awsSecurityTokenHeader, rs.AwsSecurityCredentials.SessionToken)
}
if signedRequest.Header.Get("date") == "" {
signedRequest.Header.Add(awsDateHeader, timestamp.Format(awsTimeFormatLong))
}
authorizationCode, err := rs.generateAuthentication(signedRequest, timestamp)
if err != nil {
return err
}
signedRequest.Header.Set("Authorization", authorizationCode)
req.Header = signedRequest.Header
return nil
}
func (rs *awsRequestSigner) generateAuthentication(req *http.Request, timestamp time.Time) (string, error) {
canonicalHeaderColumns, canonicalHeaderData := canonicalHeaders(req)
dateStamp := timestamp.Format(awsTimeFormatShort)
serviceName := ""
if splitHost := strings.Split(requestHost(req), "."); len(splitHost) > 0 {
serviceName = splitHost[0]
}
credentialScope := fmt.Sprintf("%s/%s/%s/%s", dateStamp, rs.RegionName, serviceName, awsRequestType)
requestString, err := canonicalRequest(req, canonicalHeaderColumns, canonicalHeaderData)
if err != nil {
return "", err
}
requestHash, err := getSha256([]byte(requestString))
if err != nil {
return "", err
}
stringToSign := fmt.Sprintf("%s\n%s\n%s\n%s", awsAlgorithm, timestamp.Format(awsTimeFormatLong), credentialScope, requestHash)
signingKey := []byte("AWS4" + rs.AwsSecurityCredentials.SecretAccessKey)
for _, signingInput := range []string{
dateStamp, rs.RegionName, serviceName, awsRequestType, stringToSign,
} {
signingKey, err = getHmacSha256(signingKey, []byte(signingInput))
if err != nil {
return "", err
}
}
return fmt.Sprintf("%s Credential=%s/%s, SignedHeaders=%s, Signature=%s", awsAlgorithm, rs.AwsSecurityCredentials.AccessKeyID, credentialScope, canonicalHeaderColumns, hex.EncodeToString(signingKey)), nil
}
type awsCredentialSource struct {
environmentID string
regionURL string
regionalCredVerificationURL string
credVerificationURL string
imdsv2SessionTokenURL string
targetResource string
requestSigner *awsRequestSigner
region string
ctx context.Context
client *http.Client
awsSecurityCredentialsSupplier AwsSecurityCredentialsSupplier
supplierOptions SupplierOptions
}
type awsRequestHeader struct {
Key string `json:"key"`
Value string `json:"value"`
}
type awsRequest struct {
URL string `json:"url"`
Method string `json:"method"`
Headers []awsRequestHeader `json:"headers"`
}
func (cs awsCredentialSource) doRequest(req *http.Request) (*http.Response, error) {
if cs.client == nil {
cs.client = oauth2.NewClient(cs.ctx, nil)
}
return cs.client.Do(req.WithContext(cs.ctx))
}
func canRetrieveRegionFromEnvironment() bool {
// The AWS region can be provided through AWS_REGION or AWS_DEFAULT_REGION. Only one is
// required.
return getenv(awsRegion) != "" || getenv(awsDefaultRegion) != ""
}
func canRetrieveSecurityCredentialFromEnvironment() bool {
// Check if both AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY are available.
return getenv(awsAccessKeyId) != "" && getenv(awsSecretAccessKey) != ""
}
func (cs awsCredentialSource) shouldUseMetadataServer() bool {
return cs.awsSecurityCredentialsSupplier == nil && (!canRetrieveRegionFromEnvironment() || !canRetrieveSecurityCredentialFromEnvironment())
}
func (cs awsCredentialSource) credentialSourceType() string {
if cs.awsSecurityCredentialsSupplier != nil {
return "programmatic"
}
return "aws"
}
func (cs awsCredentialSource) subjectToken() (string, error) {
// Set Defaults
if cs.regionalCredVerificationURL == "" {
cs.regionalCredVerificationURL = defaultRegionalCredentialVerificationUrl
}
if cs.requestSigner == nil {
headers := make(map[string]string)
if cs.shouldUseMetadataServer() {
awsSessionToken, err := cs.getAWSSessionToken()
if err != nil {
return "", err
}
if awsSessionToken != "" {
headers[awsIMDSv2SessionTokenHeader] = awsSessionToken
}
}
awsSecurityCredentials, err := cs.getSecurityCredentials(headers)
if err != nil {
return "", err
}
cs.region, err = cs.getRegion(headers)
if err != nil {
return "", err
}
cs.requestSigner = &awsRequestSigner{
RegionName: cs.region,
AwsSecurityCredentials: awsSecurityCredentials,
}
}
// Generate the signed request to AWS STS GetCallerIdentity API.
// Use the required regional endpoint. Otherwise, the request will fail.
req, err := http.NewRequest("POST", strings.Replace(cs.regionalCredVerificationURL, "{region}", cs.region, 1), nil)
if err != nil {
return "", err
}
// The full, canonical resource name of the workload identity pool
// provider, with or without the HTTPS prefix.
// Including this header as part of the signature is recommended to
// ensure data integrity.
if cs.targetResource != "" {
req.Header.Add("x-goog-cloud-target-resource", cs.targetResource)
}
cs.requestSigner.SignRequest(req)
/*
The GCP STS endpoint expects the headers to be formatted as:
# [
# {key: 'x-amz-date', value: '...'},
# {key: 'Authorization', value: '...'},
# ...
# ]
# And then serialized as:
# quote(json.dumps({
# url: '...',
# method: 'POST',
# headers: [{key: 'x-amz-date', value: '...'}, ...]
# }))
*/
awsSignedReq := awsRequest{
URL: req.URL.String(),
Method: "POST",
}
for headerKey, headerList := range req.Header {
for _, headerValue := range headerList {
awsSignedReq.Headers = append(awsSignedReq.Headers, awsRequestHeader{
Key: headerKey,
Value: headerValue,
})
}
}
sort.Slice(awsSignedReq.Headers, func(i, j int) bool {
headerCompare := strings.Compare(awsSignedReq.Headers[i].Key, awsSignedReq.Headers[j].Key)
if headerCompare == 0 {
return strings.Compare(awsSignedReq.Headers[i].Value, awsSignedReq.Headers[j].Value) < 0
}
return headerCompare < 0
})
result, err := json.Marshal(awsSignedReq)
if err != nil {
return "", err
}
return url.QueryEscape(string(result)), nil
}
func (cs *awsCredentialSource) getAWSSessionToken() (string, error) {
if cs.imdsv2SessionTokenURL == "" {
return "", nil
}
req, err := http.NewRequest("PUT", cs.imdsv2SessionTokenURL, nil)
if err != nil {
return "", err
}
req.Header.Add(awsIMDSv2SessionTtlHeader, awsIMDSv2SessionTtl)
resp, err := cs.doRequest(req)
if err != nil {
return "", err
}
defer resp.Body.Close()
respBody, err := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
if err != nil {
return "", err
}
if resp.StatusCode != 200 {
return "", fmt.Errorf("oauth2/google/externalaccount: unable to retrieve AWS session token - %s", string(respBody))
}
return string(respBody), nil
}
func (cs *awsCredentialSource) getRegion(headers map[string]string) (string, error) {
if cs.awsSecurityCredentialsSupplier != nil {
return cs.awsSecurityCredentialsSupplier.AwsRegion(cs.ctx, cs.supplierOptions)
}
if canRetrieveRegionFromEnvironment() {
if envAwsRegion := getenv(awsRegion); envAwsRegion != "" {
cs.region = envAwsRegion
return envAwsRegion, nil
}
return getenv("AWS_DEFAULT_REGION"), nil
}
if cs.regionURL == "" {
return "", errors.New("oauth2/google/externalaccount: unable to determine AWS region")
}
req, err := http.NewRequest("GET", cs.regionURL, nil)
if err != nil {
return "", err
}
for name, value := range headers {
req.Header.Add(name, value)
}
resp, err := cs.doRequest(req)
if err != nil {
return "", err
}
defer resp.Body.Close()
respBody, err := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
if err != nil {
return "", err
}
if resp.StatusCode != 200 {
return "", fmt.Errorf("oauth2/google/externalaccount: unable to retrieve AWS region - %s", string(respBody))
}
// This endpoint will return the region in format: us-east-2b.
// Only the us-east-2 part should be used.
respBodyEnd := 0
if len(respBody) > 1 {
respBodyEnd = len(respBody) - 1
}
return string(respBody[:respBodyEnd]), nil
}
func (cs *awsCredentialSource) getSecurityCredentials(headers map[string]string) (result *AwsSecurityCredentials, err error) {
if cs.awsSecurityCredentialsSupplier != nil {
return cs.awsSecurityCredentialsSupplier.AwsSecurityCredentials(cs.ctx, cs.supplierOptions)
}
if canRetrieveSecurityCredentialFromEnvironment() {
return &AwsSecurityCredentials{
AccessKeyID: getenv(awsAccessKeyId),
SecretAccessKey: getenv(awsSecretAccessKey),
SessionToken: getenv(awsSessionToken),
}, nil
}
roleName, err := cs.getMetadataRoleName(headers)
if err != nil {
return
}
credentials, err := cs.getMetadataSecurityCredentials(roleName, headers)
if err != nil {
return
}
if credentials.AccessKeyID == "" {
return result, errors.New("oauth2/google/externalaccount: missing AccessKeyId credential")
}
if credentials.SecretAccessKey == "" {
return result, errors.New("oauth2/google/externalaccount: missing SecretAccessKey credential")
}
return &credentials, nil
}
func (cs *awsCredentialSource) getMetadataSecurityCredentials(roleName string, headers map[string]string) (AwsSecurityCredentials, error) {
var result AwsSecurityCredentials
req, err := http.NewRequest("GET", fmt.Sprintf("%s/%s", cs.credVerificationURL, roleName), nil)
if err != nil {
return result, err
}
for name, value := range headers {
req.Header.Add(name, value)
}
resp, err := cs.doRequest(req)
if err != nil {
return result, err
}
defer resp.Body.Close()
respBody, err := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
if err != nil {
return result, err
}
if resp.StatusCode != 200 {
return result, fmt.Errorf("oauth2/google/externalaccount: unable to retrieve AWS security credentials - %s", string(respBody))
}
err = json.Unmarshal(respBody, &result)
return result, err
}
func (cs *awsCredentialSource) getMetadataRoleName(headers map[string]string) (string, error) {
if cs.credVerificationURL == "" {
return "", errors.New("oauth2/google/externalaccount: unable to determine the AWS metadata server security credentials endpoint")
}
req, err := http.NewRequest("GET", cs.credVerificationURL, nil)
if err != nil {
return "", err
}
for name, value := range headers {
req.Header.Add(name, value)
}
resp, err := cs.doRequest(req)
if err != nil {
return "", err
}
defer resp.Body.Close()
respBody, err := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
if err != nil {
return "", err
}
if resp.StatusCode != 200 {
return "", fmt.Errorf("oauth2/google/externalaccount: unable to retrieve AWS role name - %s", string(respBody))
}
return string(respBody), nil
}