cc-backend/internal/auth/jwt.go

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// Copyright (C) 2022 NHR@FAU, University Erlangen-Nuremberg.
// All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
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package auth
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import (
"crypto/ed25519"
"encoding/base64"
"errors"
"net/http"
"os"
"strings"
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"time"
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"github.com/ClusterCockpit/cc-backend/pkg/log"
"github.com/ClusterCockpit/cc-backend/pkg/schema"
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"github.com/golang-jwt/jwt/v4"
)
type JWTAuthenticator struct {
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auth *Authentication
publicKey ed25519.PublicKey
privateKey ed25519.PrivateKey
config *schema.JWTAuthConfig
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}
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func (ja *JWTAuthenticator) Init(auth *Authentication, conf interface{}) error {
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ja.auth = auth
ja.config = conf.(*schema.JWTAuthConfig)
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pubKey, privKey := os.Getenv("JWT_PUBLIC_KEY"), os.Getenv("JWT_PRIVATE_KEY")
if pubKey == "" || privKey == "" {
log.Warn("environment variables 'JWT_PUBLIC_KEY' or 'JWT_PRIVATE_KEY' not set (token based authentication will not work)")
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} else {
bytes, err := base64.StdEncoding.DecodeString(pubKey)
if err != nil {
log.Warn("Could not decode JWT public key")
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return err
}
ja.publicKey = ed25519.PublicKey(bytes)
bytes, err = base64.StdEncoding.DecodeString(privKey)
if err != nil {
log.Warn("Could not decode JWT private key")
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return err
}
ja.privateKey = ed25519.PrivateKey(bytes)
}
return nil
}
func (ja *JWTAuthenticator) AuthViaJWT(
rw http.ResponseWriter,
r *http.Request) (*User, error) {
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rawtoken := r.Header.Get("X-Auth-Token")
if rawtoken == "" {
rawtoken = r.Header.Get("Authorization")
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rawtoken = strings.TrimPrefix(rawtoken, "Bearer ")
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}
// there is no token
if rawtoken == "" {
return nil, nil
}
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token, err := jwt.Parse(rawtoken, func(t *jwt.Token) (interface{}, error) {
if t.Method != jwt.SigningMethodEdDSA {
return nil, errors.New("only Ed25519/EdDSA supported")
}
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return ja.publicKey, nil
})
if err != nil {
log.Warn("Error while parsing JWT token")
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return nil, err
}
if err := token.Claims.Valid(); err != nil {
log.Warn("jwt token claims are not valid")
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return nil, err
}
// Token is valid, extract payload
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claims := token.Claims.(jwt.MapClaims)
sub, _ := claims["sub"].(string)
var roles []string
// Validate user + roles from JWT against database?
if ja.config != nil && ja.config.ForceJWTValidationViaDatabase {
user, err := ja.auth.GetUser(sub)
// Deny any logins for unknown usernames
if err != nil {
log.Warn("Could not find user from JWT in internal database.")
return nil, errors.New("unknown user")
}
// Take user roles from database instead of trusting the JWT
roles = user.Roles
} else {
// Extract roles from JWT (if present)
if rawroles, ok := claims["roles"].([]interface{}); ok {
for _, rr := range rawroles {
if r, ok := rr.(string); ok {
roles = append(roles, r)
}
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}
}
}
return &User{
Username: sub,
Roles: roles,
AuthType: AuthToken,
AuthSource: -1,
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}, nil
}
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// Generate a new JWT that can be used for authentication
func (ja *JWTAuthenticator) ProvideJWT(user *User) (string, error) {
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if ja.privateKey == nil {
return "", errors.New("environment variable 'JWT_PRIVATE_KEY' not set")
}
now := time.Now()
claims := jwt.MapClaims{
"sub": user.Username,
"roles": user.Roles,
"iat": now.Unix(),
}
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if ja.config != nil && ja.config.MaxAge != 0 {
claims["exp"] = now.Add(time.Duration(ja.config.MaxAge)).Unix()
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}
return jwt.NewWithClaims(jwt.SigningMethodEdDSA, claims).SignedString(ja.privateKey)
}