implement SASL OAUTHBEARER and draft/bearer (#2122)

* implement SASL OAUTHBEARER and draft/bearer * Upgrade JWT lib * Fix an edge case in SASL EXTERNAL * Accept longer SASL responses * review fix: allow multiple token definitions * enhance tests * use SASL utilities from irc-go * test expired tokens
2026-05-12 15:28:36 -07:00 · 2024-02-13 18:58:32 -05:00
parent 8475b62da4
commit ee7f818674
58 changed files with 2868 additions and 975 deletions
--- a/irc/jwt/bearer.go
+++ b/irc/jwt/bearer.go
@@ -0,0 +1,157 @@
+// Copyright (c) 2024 Shivaram Lingamneni <slingamn@cs.stanford.edu>
+// released under the MIT license
+
+package jwt
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"strings"
+
+	jwt "github.com/golang-jwt/jwt/v5"
+)
+
+var (
+	ErrAuthDisabled        = fmt.Errorf("JWT authentication is disabled")
+	ErrNoValidAccountClaim = fmt.Errorf("JWT token did not contain an acceptable account name claim")
+)
+
+// JWTAuthConfig is the config for Ergo to accept JWTs via draft/bearer
+type JWTAuthConfig struct {
+	Enabled    bool                 `yaml:"enabled"`
+	Autocreate bool                 `yaml:"autocreate"`
+	Tokens     []JWTAuthTokenConfig `yaml:"tokens"`
+}
+
+type JWTAuthTokenConfig struct {
+	Algorithm     string `yaml:"algorithm"`
+	KeyString     string `yaml:"key"`
+	KeyFile       string `yaml:"key-file"`
+	key           any
+	parser        *jwt.Parser
+	AccountClaims []string `yaml:"account-claims"`
+	StripDomain   string   `yaml:"strip-domain"`
+}
+
+func (j *JWTAuthConfig) Postprocess() error {
+	if !j.Enabled {
+		return nil
+	}
+
+	if len(j.Tokens) == 0 {
+		return fmt.Errorf("JWT authentication enabled, but no valid tokens defined")
+	}
+
+	for i := range j.Tokens {
+		if err := j.Tokens[i].Postprocess(); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (j *JWTAuthTokenConfig) Postprocess() error {
+	keyBytes, err := j.keyBytes()
+	if err != nil {
+		return err
+	}
+
+	j.Algorithm = strings.ToLower(j.Algorithm)
+
+	var methods []string
+	switch j.Algorithm {
+	case "hmac":
+		j.key = keyBytes
+		methods = []string{"HS256", "HS384", "HS512"}
+	case "rsa":
+		rsaKey, err := jwt.ParseRSAPublicKeyFromPEM(keyBytes)
+		if err != nil {
+			return err
+		}
+		j.key = rsaKey
+		methods = []string{"RS256", "RS384", "RS512"}
+	case "eddsa":
+		eddsaKey, err := jwt.ParseEdPublicKeyFromPEM(keyBytes)
+		if err != nil {
+			return err
+		}
+		j.key = eddsaKey
+		methods = []string{"EdDSA"}
+	default:
+		return fmt.Errorf("invalid jwt algorithm: %s", j.Algorithm)
+	}
+	j.parser = jwt.NewParser(jwt.WithValidMethods(methods))
+
+	if len(j.AccountClaims) == 0 {
+		return fmt.Errorf("JWT auth enabled, but no account-claims specified")
+	}
+
+	j.StripDomain = strings.ToLower(j.StripDomain)
+	return nil
+}
+
+func (j *JWTAuthConfig) Validate(t string) (accountName string, err error) {
+	if !j.Enabled || len(j.Tokens) == 0 {
+		return "", ErrAuthDisabled
+	}
+
+	for i := range j.Tokens {
+		accountName, err = j.Tokens[i].Validate(t)
+		if err == nil {
+			return
+		}
+	}
+	return
+}
+
+func (j *JWTAuthTokenConfig) keyBytes() (result []byte, err error) {
+	if j.KeyFile != "" {
+		o, err := os.Open(j.KeyFile)
+		if err != nil {
+			return nil, err
+		}
+		return io.ReadAll(o)
+	}
+	if j.KeyString != "" {
+		return []byte(j.KeyString), nil
+	}
+	return nil, fmt.Errorf("JWT auth enabled, but no JWT key specified")
+}
+
+// implements jwt.Keyfunc
+func (j *JWTAuthTokenConfig) keyFunc(_ *jwt.Token) (interface{}, error) {
+	return j.key, nil
+}
+
+func (j *JWTAuthTokenConfig) Validate(t string) (accountName string, err error) {
+	token, err := j.parser.Parse(t, j.keyFunc)
+	if err != nil {
+		return "", err
+	}
+
+	claims, ok := token.Claims.(jwt.MapClaims)
+	if !ok {
+		// impossible with Parse (as opposed to ParseWithClaims)
+		return "", fmt.Errorf("unexpected type from parsed token claims: %T", claims)
+	}
+
+	for _, c := range j.AccountClaims {
+		if v, ok := claims[c]; ok {
+			if vstr, ok := v.(string); ok {
+				// validate and strip email addresses:
+				if idx := strings.IndexByte(vstr, '@'); idx != -1 {
+					suffix := vstr[idx+1:]
+					vstr = vstr[:idx]
+					if strings.ToLower(suffix) != j.StripDomain {
+						continue
+					}
+				}
+				return vstr, nil // success
+			}
+		}
+	}
+
+	return "", ErrNoValidAccountClaim
+}