An atproto PDS written in Go

fix service auth check (#17)

Changed files
+111 -31
server
+111 -31
server/server.go
···
"bytes"
"context"
"crypto/ecdsa"
+
"crypto/sha256"
"embed"
+
"encoding/base64"
"errors"
"fmt"
"io"
···
"github.com/labstack/echo/v4"
"github.com/labstack/echo/v4/middleware"
slogecho "github.com/samber/slog-echo"
+
"gitlab.com/yawning/secp256k1-voi"
+
secp256k1secec "gitlab.com/yawning/secp256k1-voi/secec"
"gorm.io/driver/sqlite"
"gorm.io/gorm"
)
···
return helpers.ServerError(e, nil)
}
+
// move on to oauth session middleware if this is a dpop token
if pts[0] == "DPoP" {
return next(e)
}
tokenstr := pts[1]
+
token, _, err := new(jwt.Parser).ParseUnverified(tokenstr, jwt.MapClaims{})
+
claims, ok := token.Claims.(jwt.MapClaims)
+
if !ok {
+
return helpers.InputError(e, to.StringPtr("InvalidToken"))
+
}
+
+
var did string
+
var repo *models.RepoActor
-
token, err := new(jwt.Parser).Parse(tokenstr, func(t *jwt.Token) (any, error) {
-
if _, ok := t.Method.(*jwt.SigningMethodECDSA); !ok {
-
return nil, fmt.Errorf("unsupported signing method: %v", t.Header["alg"])
+
// service auth tokens
+
lxm, hasLxm := claims["lxm"]
+
if hasLxm {
+
pts := strings.Split(e.Request().URL.String(), "/")
+
if lxm != pts[len(pts)-1] {
+
s.logger.Error("service auth lxm incorrect", "lxm", lxm, "expected", pts[len(pts)-1], "error", err)
+
return helpers.InputError(e, nil)
}
-
return s.privateKey.Public(), nil
-
})
-
if err != nil {
-
s.logger.Error("error parsing jwt", "error", err)
-
// NOTE: https://github.com/bluesky-social/atproto/discussions/3319
-
return e.JSON(400, map[string]string{"error": "ExpiredToken", "message": "token has expired"})
+
maybeDid, ok := claims["iss"].(string)
+
if !ok {
+
s.logger.Error("no iss in service auth token", "error", err)
+
return helpers.InputError(e, nil)
+
}
+
did = maybeDid
+
+
maybeRepo, err := s.getRepoActorByDid(did)
+
if err != nil {
+
s.logger.Error("error fetching repo", "error", err)
+
return helpers.ServerError(e, nil)
+
}
+
repo = maybeRepo
}
-
claims, ok := token.Claims.(jwt.MapClaims)
-
if !ok || !token.Valid {
-
return helpers.InputError(e, to.StringPtr("InvalidToken"))
+
if token.Header["alg"] != "ES256K" {
+
token, err = new(jwt.Parser).Parse(tokenstr, func(t *jwt.Token) (any, error) {
+
if _, ok := t.Method.(*jwt.SigningMethodECDSA); !ok {
+
return nil, fmt.Errorf("unsupported signing method: %v", t.Header["alg"])
+
}
+
return s.privateKey.Public(), nil
+
})
+
if err != nil {
+
s.logger.Error("error parsing jwt", "error", err)
+
// NOTE: https://github.com/bluesky-social/atproto/discussions/3319
+
return e.JSON(400, map[string]string{"error": "ExpiredToken", "message": "token has expired"})
+
}
+
+
if !token.Valid {
+
return helpers.InputError(e, to.StringPtr("InvalidToken"))
+
}
+
} else {
+
kpts := strings.Split(tokenstr, ".")
+
signingInput := kpts[0] + "." + kpts[1]
+
hash := sha256.Sum256([]byte(signingInput))
+
sigBytes, err := base64.RawURLEncoding.DecodeString(kpts[2])
+
if err != nil {
+
s.logger.Error("error decoding signature bytes", "error", err)
+
return helpers.ServerError(e, nil)
+
}
+
+
if len(sigBytes) != 64 {
+
s.logger.Error("incorrect sigbytes length", "length", len(sigBytes))
+
return helpers.ServerError(e, nil)
+
}
+
+
rBytes := sigBytes[:32]
+
sBytes := sigBytes[32:]
+
rr, _ := secp256k1.NewScalarFromBytes((*[32]byte)(rBytes))
+
ss, _ := secp256k1.NewScalarFromBytes((*[32]byte)(sBytes))
+
+
sk, err := secp256k1secec.NewPrivateKey(repo.SigningKey)
+
if err != nil {
+
s.logger.Error("can't load private key", "error", err)
+
return err
+
}
+
+
pubKey, ok := sk.Public().(*secp256k1secec.PublicKey)
+
if !ok {
+
s.logger.Error("error getting public key from sk")
+
return helpers.ServerError(e, nil)
+
}
+
+
verified := pubKey.VerifyRaw(hash[:], rr, ss)
+
if !verified {
+
s.logger.Error("error verifying", "error", err)
+
return helpers.ServerError(e, nil)
+
}
}
isRefresh := e.Request().URL.Path == "/xrpc/com.atproto.server.refreshSession"
-
scope := claims["scope"].(string)
+
scope, _ := claims["scope"].(string)
if isRefresh && scope != "com.atproto.refresh" {
return helpers.InputError(e, to.StringPtr("InvalidToken"))
-
} else if !isRefresh && scope != "com.atproto.access" {
+
} else if !hasLxm && !isRefresh && scope != "com.atproto.access" {
return helpers.InputError(e, to.StringPtr("InvalidToken"))
}
···
table = "refresh_tokens"
}
-
type Result struct {
-
Found bool
-
}
-
var result Result
-
if err := s.db.Raw("SELECT EXISTS(SELECT 1 FROM "+table+" WHERE token = ?) AS found", nil, tokenstr).Scan(&result).Error; err != nil {
-
if err == gorm.ErrRecordNotFound {
-
return helpers.InputError(e, to.StringPtr("InvalidToken"))
+
if isRefresh {
+
type Result struct {
+
Found bool
}
+
var result Result
+
if err := s.db.Raw("SELECT EXISTS(SELECT 1 FROM "+table+" WHERE token = ?) AS found", nil, tokenstr).Scan(&result).Error; err != nil {
+
if err == gorm.ErrRecordNotFound {
+
return helpers.InputError(e, to.StringPtr("InvalidToken"))
+
}
-
s.logger.Error("error getting token from db", "error", err)
-
return helpers.ServerError(e, nil)
-
}
+
s.logger.Error("error getting token from db", "error", err)
+
return helpers.ServerError(e, nil)
+
}
-
if !result.Found {
-
return helpers.InputError(e, to.StringPtr("InvalidToken"))
+
if !result.Found {
+
return helpers.InputError(e, to.StringPtr("InvalidToken"))
+
}
}
exp, ok := claims["exp"].(float64)
···
return helpers.InputError(e, to.StringPtr("ExpiredToken"))
}
-
repo, err := s.getRepoActorByDid(claims["sub"].(string))
-
if err != nil {
-
s.logger.Error("error fetching repo", "error", err)
-
return helpers.ServerError(e, nil)
+
if repo == nil {
+
maybeRepo, err := s.getRepoActorByDid(claims["sub"].(string))
+
if err != nil {
+
s.logger.Error("error fetching repo", "error", err)
+
return helpers.ServerError(e, nil)
+
}
+
repo = maybeRepo
+
did = repo.Repo.Did
}
e.Set("repo", repo)
-
e.Set("did", claims["sub"])
+
e.Set("did", did)
e.Set("token", tokenstr)
if err := next(e); err != nil {