gitea/routers/api/packages/chef/auth.go

275 lines
6.2 KiB
Go
Raw Normal View History

// Copyright 2023 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package chef
import (
"context"
"crypto"
"crypto/rsa"
"crypto/sha1"
"crypto/sha256"
"crypto/x509"
"encoding/base64"
"encoding/pem"
"fmt"
"hash"
"math/big"
"net/http"
"path"
"regexp"
"slices"
"strconv"
"strings"
"time"
user_model "code.gitea.io/gitea/models/user"
chef_module "code.gitea.io/gitea/modules/packages/chef"
"code.gitea.io/gitea/modules/util"
"code.gitea.io/gitea/services/auth"
)
const (
maxTimeDifference = 10 * time.Minute
)
var (
algorithmPattern = regexp.MustCompile(`algorithm=(\w+)`)
versionPattern = regexp.MustCompile(`version=(\d+\.\d+)`)
authorizationPattern = regexp.MustCompile(`\AX-Ops-Authorization-(\d+)`)
_ auth.Method = &Auth{}
)
// Documentation:
// https://docs.chef.io/server/api_chef_server/#required-headers
// https://github.com/chef-boneyard/chef-rfc/blob/master/rfc065-sign-v1.3.md
// https://github.com/chef/mixlib-authentication/blob/bc8adbef833d4be23dc78cb23e6fe44b51ebc34f/lib/mixlib/authentication/signedheaderauth.rb
type Auth struct{}
func (a *Auth) Name() string {
return "chef"
}
// Verify extracts the user from the signed request
// If the request is signed with the user private key the user is verified.
func (a *Auth) Verify(req *http.Request, w http.ResponseWriter, store auth.DataStore, sess auth.SessionStore) (*user_model.User, error) {
u, err := getUserFromRequest(req)
if err != nil {
return nil, err
}
if u == nil {
return nil, nil
}
pub, err := getUserPublicKey(req.Context(), u)
if err != nil {
return nil, err
}
if err := verifyTimestamp(req); err != nil {
return nil, err
}
version, err := getSignVersion(req)
if err != nil {
return nil, err
}
if err := verifySignedHeaders(req, version, pub.(*rsa.PublicKey)); err != nil {
return nil, err
}
return u, nil
}
func getUserFromRequest(req *http.Request) (*user_model.User, error) {
username := req.Header.Get("X-Ops-Userid")
if username == "" {
return nil, nil
}
return user_model.GetUserByName(req.Context(), username)
}
func getUserPublicKey(ctx context.Context, u *user_model.User) (crypto.PublicKey, error) {
pubKey, err := user_model.GetSetting(ctx, u.ID, chef_module.SettingPublicPem)
if err != nil {
return nil, err
}
pubPem, _ := pem.Decode([]byte(pubKey))
return x509.ParsePKIXPublicKey(pubPem.Bytes)
}
func verifyTimestamp(req *http.Request) error {
hdr := req.Header.Get("X-Ops-Timestamp")
if hdr == "" {
return util.NewInvalidArgumentErrorf("X-Ops-Timestamp header missing")
}
ts, err := time.Parse(time.RFC3339, hdr)
if err != nil {
return err
}
diff := time.Now().UTC().Sub(ts)
if diff < 0 {
diff = -diff
}
if diff > maxTimeDifference {
return fmt.Errorf("time difference")
}
return nil
}
func getSignVersion(req *http.Request) (string, error) {
hdr := req.Header.Get("X-Ops-Sign")
if hdr == "" {
return "", util.NewInvalidArgumentErrorf("X-Ops-Sign header missing")
}
m := versionPattern.FindStringSubmatch(hdr)
if len(m) != 2 {
return "", util.NewInvalidArgumentErrorf("invalid X-Ops-Sign header")
}
switch m[1] {
case "1.0", "1.1", "1.2", "1.3":
default:
return "", util.NewInvalidArgumentErrorf("unsupported version")
}
version := m[1]
m = algorithmPattern.FindStringSubmatch(hdr)
if len(m) == 2 && m[1] != "sha1" && !(m[1] == "sha256" && version == "1.3") {
return "", util.NewInvalidArgumentErrorf("unsupported algorithm")
}
return version, nil
}
func verifySignedHeaders(req *http.Request, version string, pub *rsa.PublicKey) error {
authorizationData, err := getAuthorizationData(req)
if err != nil {
return err
}
checkData := buildCheckData(req, version)
switch version {
case "1.3":
return verifyDataNew(authorizationData, checkData, pub, crypto.SHA256)
case "1.2":
return verifyDataNew(authorizationData, checkData, pub, crypto.SHA1)
default:
return verifyDataOld(authorizationData, checkData, pub)
}
}
func getAuthorizationData(req *http.Request) ([]byte, error) {
valueList := make(map[int]string)
for k, vs := range req.Header {
if m := authorizationPattern.FindStringSubmatch(k); m != nil {
index, _ := strconv.Atoi(m[1])
var v string
if len(vs) == 0 {
v = ""
} else {
v = vs[0]
}
valueList[index] = v
}
}
tmp := make([]string, len(valueList))
for k, v := range valueList {
if k > len(tmp) {
return nil, fmt.Errorf("invalid X-Ops-Authorization headers")
}
tmp[k-1] = v
}
return base64.StdEncoding.DecodeString(strings.Join(tmp, ""))
}
func buildCheckData(req *http.Request, version string) []byte {
username := req.Header.Get("X-Ops-Userid")
if version != "1.0" && version != "1.3" {
sum := sha1.Sum([]byte(username))
username = base64.StdEncoding.EncodeToString(sum[:])
}
var data string
if version == "1.3" {
data = fmt.Sprintf(
"Method:%s\nPath:%s\nX-Ops-Content-Hash:%s\nX-Ops-Sign:version=%s\nX-Ops-Timestamp:%s\nX-Ops-UserId:%s\nX-Ops-Server-API-Version:%s",
req.Method,
path.Clean(req.URL.Path),
req.Header.Get("X-Ops-Content-Hash"),
version,
req.Header.Get("X-Ops-Timestamp"),
username,
req.Header.Get("X-Ops-Server-Api-Version"),
)
} else {
sum := sha1.Sum([]byte(path.Clean(req.URL.Path)))
data = fmt.Sprintf(
"Method:%s\nHashed Path:%s\nX-Ops-Content-Hash:%s\nX-Ops-Timestamp:%s\nX-Ops-UserId:%s",
req.Method,
base64.StdEncoding.EncodeToString(sum[:]),
req.Header.Get("X-Ops-Content-Hash"),
req.Header.Get("X-Ops-Timestamp"),
username,
)
}
return []byte(data)
}
func verifyDataNew(signature, data []byte, pub *rsa.PublicKey, algo crypto.Hash) error {
var h hash.Hash
if algo == crypto.SHA256 {
h = sha256.New()
} else {
h = sha1.New()
}
if _, err := h.Write(data); err != nil {
return err
}
return rsa.VerifyPKCS1v15(pub, algo, h.Sum(nil), signature)
}
func verifyDataOld(signature, data []byte, pub *rsa.PublicKey) error {
c := new(big.Int)
m := new(big.Int)
m.SetBytes(signature)
e := big.NewInt(int64(pub.E))
c.Exp(m, e, pub.N)
out := c.Bytes()
skip := 0
for i := 2; i < len(out); i++ {
if i+1 >= len(out) {
break
}
if out[i] == 0xFF && out[i+1] == 0 {
skip = i + 2
break
}
}
if !slices.Equal(out[skip:], data) {
return fmt.Errorf("could not verify signature")
}
return nil
}