Implements the frontend logic for gNSI Authz

Signed-off-by: kanchanavelusamy <velusamyk@google.com>

Author: kanchanavelusamy

gnmi_server/gnsi_authz.go

@@ -0,0 +1,292 @@
+package gnmi
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	log "github.com/golang/glog"
+	"github.com/openconfig/gnsi/authz"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+	"io"
+	"os"
+	"path/filepath"
+	"strconv"
+	"sync"
+	"time"
+)
+
+var (
+	authzMu sync.Mutex
+)
+
+var (
+	// Step 1: Point the variable to the real function by default
+	authenticateFunc = authenticate
+)
+
+const (
+	authzP4rtTbl      string = "AUTHZ_POLICY|p4rt"
+	authzGnxiTbl      string = "AUTHZ_POLICY|gnxi"
+	authzVersionFld   string = "authz_version"
+	authzCreatedOnFld string = "authz_created_on"
+)
+
+type GNSIAuthzServer struct {
+	*Server
+	authzMetadata     *AuthzMetadata
+	authzMetadataCopy AuthzMetadata
+	authz.UnimplementedAuthzServer
+}
+
+func (srv *GNSIAuthzServer) Probe(context.Context, *authz.ProbeRequest) (*authz.ProbeResponse, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method Probe not implemented")
+}
+func (srv *GNSIAuthzServer) Get(context.Context, *authz.GetRequest) (*authz.GetResponse, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method Get not implemented")
+}
+func NewGNSIAuthzServer(srv *Server) *GNSIAuthzServer {
+	ret := &GNSIAuthzServer{
+		Server:        srv,
+		authzMetadata: NewAuthzMetadata(),
+	}
+	log.V(2).Infof("gnsi: loading authz metadata from %s", srv.config.AuthzMetaFile)
+	log.V(2).Infof("gnsi: loading authz policy from %s", srv.config.AuthzPolicyFile)
+	if err := ret.loadAuthzFreshness(srv.config.AuthzMetaFile); err != nil {
+		log.V(0).Info(err)
+	}
+	ret.authzMetadataCopy = *ret.authzMetadata
+	ret.writeAuthzMetadataToDB(authzVersionFld, ret.authzMetadata.AuthzVersion)
+	ret.writeAuthzMetadataToDB(authzCreatedOnFld, ret.authzMetadata.AuthzCreatedOn)
+	return ret
+}
+
+// Rotate implements the gNSI.authz.Rotate RPC.
+func (srv *GNSIAuthzServer) Rotate(stream authz.Authz_RotateServer) error {
+	ctx := stream.Context()
+	log.Infof("GNSI Authz Rotate RPC")
+	_, err := authenticateFunc(srv.config, ctx, "gnoi", false)
+	if err != nil {
+		log.Errorf("authentication failed in Rotate RPC: %v", err)
+		return err
+	}
+	session := time.Now().Nanosecond()
+	// Concurrent Authz RPCs are not allowed.
+	if !authzMu.TryLock() {
+		log.V(0).Infof("[%v]gNSI: authz.Rotate already in use", session)
+		return status.Errorf(codes.Aborted, "concurrent authz.Rotate RPCs are not allowed")
+	}
+	defer authzMu.Unlock()
+
+	log.V(2).Infof("[%v]gNSI: Begin authz.Rotate", session)
+	defer log.V(2).Infof("[%v]gNSI: End authz.Rotate", session)
+
+	srv.checkpointAuthzFreshness()
+	if err := srv.checkpointAuthzFile(); err != nil {
+		log.V(0).Infof("Failure during Authz checkpoint: %v", err)
+	}
+	for {
+		req, err := stream.Recv()
+		if err == io.EOF {
+			log.V(0).Infof("[%v]gNSI: Received unexpected EOF", session)
+			// Connection closed without Finalize message. Revert all changes made until now.
+			if err := copyFile(srv.config.AuthzPolicyFile+backupExt, srv.config.AuthzPolicyFile); err != nil {
+				log.V(0).Infof("[%v]gnsi: failed to revert authz policy file (%v): %v", session, srv.config.AuthzPolicyFile, err)
+			}
+			srv.revertAuthzFileFreshness()
+			return status.Errorf(codes.Aborted, "No Finalize message")
+		}
+		if err != nil {
+			log.V(0).Infof("[%v]gnsi: while processing a rotate request got error: `%v`. Reverting to last good state.", session, err)
+			// Connection closed without Finalize message. Revert all changes made until now.
+			if err := copyFile(srv.config.AuthzPolicyFile+backupExt, srv.config.AuthzPolicyFile); err != nil {
+				log.V(0).Infof("[%v]gnsi: failed to revert authz policy file (%v): %v", session, srv.config.AuthzPolicyFile, err)
+			}
+			srv.revertAuthzFileFreshness()
+			return status.Errorf(codes.Aborted, err.Error())
+		}
+		if endReq := req.GetFinalizeRotation(); endReq != nil {
+			// This is the last message. All changes are final.
+			log.V(2).Infof("[%v]gNSI: Received Finalize: %v", session, endReq)
+			srv.commitAuthzFileChanges()
+			srv.saveAuthzFileFreshess(srv.config.AuthzMetaFile)
+			return nil
+		}
+		resp, err := srv.processRotateRequest(req)
+		if err != nil {
+			log.V(0).Infof("[%v]gnsi: while processing a rotate request got error: `%v`. Reverting to last good state.", session, err)
+			// Connection closed without Finalize message. Revert all changes made until now.
+			if err := copyFile(srv.config.AuthzPolicyFile+backupExt, srv.config.AuthzPolicyFile); err != nil {
+				log.V(0).Infof("[%v]gnsi: failed to revert authz policy file (%v): %v", session, srv.config.AuthzPolicyFile, err)
+			}
+			srv.revertAuthzFileFreshness()
+			return err
+		}
+		if err := stream.Send(resp); err != nil {
+			log.V(0).Infof("[%v]gnsi: while processing a rotate request got error: `%v`. Reverting to last good state.", session, err)
+			// Connection closed without Finalize message. Revert all changes made until now.
+			if err := copyFile(srv.config.AuthzPolicyFile+backupExt, srv.config.AuthzPolicyFile); err != nil {
+				log.V(0).Infof("[%v]gnsi: failed to revert authz policy file (%v): %v", session, srv.config.AuthzPolicyFile, err)
+			}
+			srv.revertAuthzFileFreshness()
+			return status.Errorf(codes.Aborted, err.Error())
+		}
+	}
+}
+
+func (srv *GNSIAuthzServer) processRotateRequest(req *authz.RotateAuthzRequest) (*authz.RotateAuthzResponse, error) {
+	policyReq := req.GetUploadRequest()
+	if policyReq == nil {
+		return nil, status.Errorf(codes.Aborted, `Unknown request: "%v"`, req)
+	}
+	log.V(2).Infof("received a gNSI.Authz UploadRequest request message")
+	log.V(3).Infof("request message: %v", policyReq)
+	if len(policyReq.GetPolicy()) == 0 {
+		return nil, status.Errorf(codes.Aborted, "Authz policy cannot be empty!")
+	}
+	if len(policyReq.GetVersion()) == 0 {
+		return nil, status.Errorf(codes.Aborted, "Authz policy version cannot be empty!")
+	}
+	if !json.Valid([]byte(policyReq.GetPolicy())) {
+		return nil, status.Errorf(codes.Aborted, "Authz policy `%v` is malformed", policyReq.GetPolicy())
+	}
+	if err := fileCheck(srv.config.AuthzPolicyFile); err != nil {
+		return nil, status.Errorf(codes.NotFound, "Error in reading file %s: %v. Please try Install.", srv.config.AuthzPolicyFile, err)
+	}
+	if srv.gnsiAuthz.authzMetadata.AuthzVersion == policyReq.GetVersion() && !req.GetForceOverwrite() {
+		return nil, status.Errorf(codes.AlreadyExists, "Authz with version `%v` already exists", policyReq.GetVersion())
+	}
+	if err := srv.writeAuthzMetadataToDB(authzVersionFld, policyReq.GetVersion()); err != nil {
+		return nil, status.Errorf(codes.Aborted, err.Error())
+	}
+	if err := srv.writeAuthzMetadataToDB(authzCreatedOnFld, strconv.FormatUint(policyReq.GetCreatedOn(), 10)); err != nil {
+		return nil, status.Errorf(codes.Aborted, err.Error())
+	}
+	if err := srv.saveToAuthzFile(policyReq.GetPolicy()); err != nil {
+		return nil, status.Errorf(codes.Aborted, err.Error())
+	}
+	resp := &authz.RotateAuthzResponse{
+		RotateResponse: &authz.RotateAuthzResponse_UploadResponse{},
+	}
+	return resp, nil
+}
+
+func (srv *GNSIAuthzServer) saveToAuthzFile(p string) error {
+	tmpDst, err := os.CreateTemp(filepath.Dir(srv.config.AuthzPolicyFile), filepath.Base(srv.config.AuthzPolicyFile))
+	if err != nil {
+		return err
+	}
+	if _, err := tmpDst.Write([]byte(p)); err != nil {
+		if e := os.Remove(tmpDst.Name()); e != nil {
+			log.V(1).Infof("Failed to cleanup file: %v: %v", tmpDst.Name(), e)
+		}
+		return err
+	}
+	if err := tmpDst.Close(); err != nil {
+		if e := os.Remove(tmpDst.Name()); e != nil {
+			log.V(1).Infof("Failed to cleanup file: %v: %v", tmpDst.Name(), e)
+		}
+		return err
+	}
+	if err := os.Rename(tmpDst.Name(), srv.config.AuthzPolicyFile); err != nil {
+		if e := os.Remove(tmpDst.Name()); e != nil {
+			log.V(1).Infof("Failed to cleanup file: %v: %v", tmpDst.Name(), e)
+		}
+		return err
+	}
+	return os.Chmod(srv.config.AuthzPolicyFile, 0600)
+}
+
+func (srv *GNSIAuthzServer) checkpointAuthzFile() error {
+	log.V(2).Infof("Checkpoint authz file: %v", srv.config.AuthzPolicyFile)
+	return copyFile(srv.config.AuthzPolicyFile, srv.config.AuthzPolicyFile+backupExt)
+}
+
+func (srv *GNSIAuthzServer) commitAuthzFileChanges() error {
+	// Check if the active policy file exists.
+	srcStat, err := os.Stat(srv.config.AuthzPolicyFile)
+	if err != nil {
+		return err
+	}
+	if !srcStat.Mode().IsRegular() {
+		return fmt.Errorf("%s is not a regular file", srv.config.AuthzPolicyFile)
+	}
+	// OK. Now the backup can be deleted.
+	backup := srv.config.AuthzPolicyFile + backupExt
+	backupStat, err := os.Stat(backup)
+	if err != nil {
+		// Already does not exist.
+		return nil
+	}
+	if !backupStat.Mode().IsRegular() {
+		return fmt.Errorf("%s is not a regular file; did not remove it.", backup)
+	}
+	return os.Remove(backup)
+}
+
+// writeAuthzMetadataToDB writes the credentials freshness data to the DB.
+func (srv *GNSIAuthzServer) writeAuthzMetadataToDB(fld, val string) error {
+	if err := writeCredentialsMetadataToDB(authzP4rtTbl, "", fld, val); err != nil {
+		return err
+	}
+	if err := writeCredentialsMetadataToDB(authzGnxiTbl, "", fld, val); err != nil {
+		return err
+	}
+	switch fld {
+	case authzVersionFld:
+		srv.authzMetadata.AuthzVersion = val
+	case authzCreatedOnFld:
+		srv.authzMetadata.AuthzCreatedOn = val
+	}
+	return nil
+}
+
+type AuthzMetadata struct {
+	AuthzVersion   string `json:"authz_version"`
+	AuthzCreatedOn string `json:"authz_created_on"`
+}
+
+func NewAuthzMetadata() *AuthzMetadata {
+	return &AuthzMetadata{
+		AuthzVersion:   "unknown",
+		AuthzCreatedOn: "0",
+	}
+}
+
+func (srv *GNSIAuthzServer) checkpointAuthzFreshness() {
+	log.V(2).Infof("checkpoint authz freshness")
+	srv.authzMetadataCopy = *srv.authzMetadata
+}
+
+func (srv *GNSIAuthzServer) revertAuthzFileFreshness() {
+	log.V(2).Infof("revert authz freshness")
+	srv.writeAuthzMetadataToDB(authzVersionFld, srv.authzMetadataCopy.AuthzVersion)
+	srv.writeAuthzMetadataToDB(authzCreatedOnFld, srv.authzMetadataCopy.AuthzCreatedOn)
+}
+
+func (srv *GNSIAuthzServer) saveAuthzFileFreshess(path string) error {
+	log.V(2).Infof("save authz metadata to file: %v", path)
+	buf := new(bytes.Buffer)
+	enc := json.NewEncoder(buf)
+	if err := enc.Encode(*srv.authzMetadata); err != nil {
+		log.V(0).Info(err)
+		return err
+	}
+	if err := os.WriteFile(path, buf.Bytes(), 0644); err != nil {
+		if e := os.Remove(path); e != nil {
+			err = fmt.Errorf("Write %s failed: %w; Cleanup failed", path, err)
+		}
+		return err
+	}
+	return nil
+}
+
+func (srv *GNSIAuthzServer) loadAuthzFreshness(path string) error {
+	log.V(2).Infof("load authz metadata from file: %v", path)
+	bytes, err := os.ReadFile(path)
+	if err != nil {
+		return err
+	}
+	return json.Unmarshal(bytes, srv.authzMetadata)
+}