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-rw-r--r--routers/api/packages/chef/auth.go274
1 files changed, 274 insertions, 0 deletions
diff --git a/routers/api/packages/chef/auth.go b/routers/api/packages/chef/auth.go
new file mode 100644
index 0000000..a790e9a
--- /dev/null
+++ b/routers/api/packages/chef/auth.go
@@ -0,0 +1,274 @@
+// 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
+}