Refactor legacy code, fix LFS auth bypass, fix symlink bypass (#35708)

cmd/serv.go

@@ -13,7 +13,6 @@ import (
 	"path/filepath"
 	"strconv"
 	"strings"
-	"time"
 	"unicode"
 
 	asymkey_model "code.gitea.io/gitea/models/asymkey"
@@ -31,7 +30,6 @@ import (
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/services/lfs"
 
-	"github.com/golang-jwt/jwt/v5"
 	"github.com/kballard/go-shellquote"
 	"github.com/urfave/cli/v2"
 )
@@ -131,27 +129,6 @@ func getAccessMode(verb, lfsVerb string) perm.AccessMode {
 	return perm.AccessModeNone
 }
 
-func getLFSAuthToken(ctx context.Context, lfsVerb string, results *private.ServCommandResults) (string, error) {
-	now := time.Now()
-	claims := lfs.Claims{
-		RegisteredClaims: jwt.RegisteredClaims{
-			ExpiresAt: jwt.NewNumericDate(now.Add(setting.LFS.HTTPAuthExpiry)),
-			NotBefore: jwt.NewNumericDate(now),
-		},
-		RepoID: results.RepoID,
-		Op:     lfsVerb,
-		UserID: results.UserID,
-	}
-	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
-
-	// Sign and get the complete encoded token as a string using the secret
-	tokenString, err := token.SignedString(setting.LFS.JWTSecretBytes)
-	if err != nil {
-		return "", fail(ctx, "Failed to sign JWT Token", "Failed to sign JWT token: %v", err)
-	}
-	return "Bearer " + tokenString, nil
-}
-
 func runServ(c *cli.Context) error {
 	ctx, cancel := installSignals()
 	defer cancel()
@@ -284,7 +261,7 @@ func runServ(c *cli.Context) error {
 
 	// LFS SSH protocol
 	if verb == git.CmdVerbLfsTransfer {
-		token, err := getLFSAuthToken(ctx, lfsVerb, results)
+		token, err := lfs.GetLFSAuthTokenWithBearer(lfs.AuthTokenOptions{Op: lfsVerb, UserID: results.UserID, RepoID: results.RepoID})
 		if err != nil {
 			return err
 		}
@@ -295,7 +272,7 @@ func runServ(c *cli.Context) error {
 	if verb == git.CmdVerbLfsAuthenticate {
 		url := fmt.Sprintf("%s%s/%s.git/info/lfs", setting.AppURL, url.PathEscape(results.OwnerName), url.PathEscape(results.RepoName))
 
-		token, err := getLFSAuthToken(ctx, lfsVerb, results)
+		token, err := lfs.GetLFSAuthTokenWithBearer(lfs.AuthTokenOptions{Op: lfsVerb, UserID: results.UserID, RepoID: results.RepoID})
 		if err != nil {
 			return err
 		}

models/asymkey/ssh_key.go

@@ -67,13 +67,6 @@ func (key *PublicKey) OmitEmail() string {
 	return strings.Join(strings.Split(key.Content, " ")[:2], " ")
 }
 
-// AuthorizedString returns formatted public key string for authorized_keys file.
-//
-// TODO: Consider dropping this function
-func (key *PublicKey) AuthorizedString() string {
-	return AuthorizedStringForKey(key)
-}
-
 func addKey(ctx context.Context, key *PublicKey) (err error) {
 	if len(key.Fingerprint) == 0 {
 		key.Fingerprint, err = CalcFingerprint(key.Content)

models/asymkey/ssh_key_authorized_keys.go

@@ -17,30 +17,14 @@ import (
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/setting"
 	"code.gitea.io/gitea/modules/util"
-)
 
-//  _____          __  .__                 .__                  .___
-// /  _  \  __ ___/  |_|  |__   ___________|__|_______ ____   __| _/
-// /  /_\  \|  |  \   __\  |  \ /  _ \_  __ \  \___   // __ \ / __ |
-// /    |    \  |  /|  | |   Y  (  <_> )  | \/  |/    /\  ___// /_/ |
-// \____|__  /____/ |__| |___|  /\____/|__|  |__/_____ \\___  >____ |
-//         \/                 \/                      \/    \/     \/
-// ____  __.
-// |    |/ _|____ ___.__. ______
-// |      <_/ __ <   |  |/  ___/
-// |    |  \  ___/\___  |\___ \
-// |____|__ \___  > ____/____  >
-//         \/   \/\/         \/
-//
-// This file contains functions for creating authorized_keys files
-//
-// There is a dependence on the database within RegeneratePublicKeys however most of these functions probably belong in a module
-
-const (
-	tplCommentPrefix = `# gitea public key`
-	tplPublicKey     = tplCommentPrefix + "\n" + `command=%s,no-port-forwarding,no-X11-forwarding,no-agent-forwarding,no-pty,no-user-rc,restrict %s` + "\n"
+	"golang.org/x/crypto/ssh"
 )
 
+// AuthorizedStringCommentPrefix is a magic tag
+// some functions like RegeneratePublicKeys needs this tag to skip the keys generated by Gitea, while keep other keys
+const AuthorizedStringCommentPrefix = `# gitea public key`
+
 var sshOpLocker sync.Mutex
 
 func WithSSHOpLocker(f func() error) error {
@@ -50,17 +34,45 @@ func WithSSHOpLocker(f func() error) error {
 }
 
 // AuthorizedStringForKey creates the authorized keys string appropriate for the provided key
-func AuthorizedStringForKey(key *PublicKey) string {
+func AuthorizedStringForKey(key *PublicKey) (string, error) {
 	sb := &strings.Builder{}
-	_ = setting.SSH.AuthorizedKeysCommandTemplateTemplate.Execute(sb, map[string]any{
+	_, err := writeAuthorizedStringForKey(key, sb)
+	return sb.String(), err
+}
+
+// WriteAuthorizedStringForValidKey writes the authorized key for the provided key. If the key is invalid, it does nothing.
+func WriteAuthorizedStringForValidKey(key *PublicKey, w io.Writer) error {
+	validKey, err := writeAuthorizedStringForKey(key, w)
+	if !validKey {
+		log.Debug("WriteAuthorizedStringForValidKey: key %s is not valid: %v", key, err)
+		return nil
+	}
+	return err
+}
+
+func writeAuthorizedStringForKey(key *PublicKey, w io.Writer) (keyValid bool, err error) {
+	const tpl = AuthorizedStringCommentPrefix + "\n" + `command=%s,no-port-forwarding,no-X11-forwarding,no-agent-forwarding,no-pty,no-user-rc,restrict %s %s` + "\n"
+	pubKey, _, _, _, err := ssh.ParseAuthorizedKey([]byte(key.Content))
+	if err != nil {
+		return false, err
+	}
+	// now the key is valid, the code below could only return template/IO related errors
+	sbCmd := &strings.Builder{}
+	err = setting.SSH.AuthorizedKeysCommandTemplateTemplate.Execute(sbCmd, map[string]any{
 		"AppPath":     util.ShellEscape(setting.AppPath),
 		"AppWorkPath": util.ShellEscape(setting.AppWorkPath),
 		"CustomConf":  util.ShellEscape(setting.CustomConf),
 		"CustomPath":  util.ShellEscape(setting.CustomPath),
 		"Key":         key,
 	})
-
-	return fmt.Sprintf(tplPublicKey, util.ShellEscape(sb.String()), key.Content)
+	if err != nil {
+		return true, err
+	}
+	sshCommandEscaped := util.ShellEscape(sbCmd.String())
+	sshKeyMarshalled := strings.TrimSpace(string(ssh.MarshalAuthorizedKey(pubKey)))
+	sshKeyComment := fmt.Sprintf("user-%d", key.OwnerID)
+	_, err = fmt.Fprintf(w, tpl, sshCommandEscaped, sshKeyMarshalled, sshKeyComment)
+	return true, err
 }
 
 // appendAuthorizedKeysToFile appends new SSH keys' content to authorized_keys file.
@@ -112,18 +124,17 @@ func appendAuthorizedKeysToFile(keys ...*PublicKey) error {
 		if key.Type == KeyTypePrincipal {
 			continue
 		}
-		if _, err = f.WriteString(key.AuthorizedString()); err != nil {
+		if err = WriteAuthorizedStringForValidKey(key, f); err != nil {
 			return err
 		}
 	}
 	return nil
 }
 
 // RegeneratePublicKeys regenerates the authorized_keys file
-func RegeneratePublicKeys(ctx context.Context, t io.StringWriter) error {
+func RegeneratePublicKeys(ctx context.Context, t io.Writer) error {
 	if err := db.GetEngine(ctx).Where("type != ?", KeyTypePrincipal).Iterate(new(PublicKey), func(idx int, bean any) (err error) {
-		_, err = t.WriteString((bean.(*PublicKey)).AuthorizedString())
-		return err
+		return WriteAuthorizedStringForValidKey(bean.(*PublicKey), t)
 	}); err != nil {
 		return err
 	}
@@ -144,11 +155,11 @@ func RegeneratePublicKeys(ctx context.Context, t io.StringWriter) error {
 		scanner := bufio.NewScanner(f)
 		for scanner.Scan() {
 			line := scanner.Text()
-			if strings.HasPrefix(line, tplCommentPrefix) {
+			if strings.HasPrefix(line, AuthorizedStringCommentPrefix) {
 				scanner.Scan()
 				continue
 			}
-			_, err = t.WriteString(line + "\n")
+			_, err = io.WriteString(t, line+"\n")
 			if err != nil {
 				return err
 			}

models/repo/upload.go

@@ -137,16 +137,9 @@ func DeleteUploads(ctx context.Context, uploads ...*Upload) (err error) {
 
 	for _, upload := range uploads {
 		localPath := upload.LocalPath()
-		isFile, err := util.IsFile(localPath)
-		if err != nil {
-			log.Error("Unable to check if %s is a file. Error: %v", localPath, err)
-		}
-		if !isFile {
-			continue
-		}
-
 		if err := util.Remove(localPath); err != nil {
-			return fmt.Errorf("remove upload: %w", err)
+			// just continue, don't fail the whole operation if a file is missing (removed by others)
+			log.Error("unable to remove upload file %s: %v", localPath, err)
 		}
 	}
 

modules/git/hook.go

@@ -51,30 +51,16 @@ func GetHook(repoPath, name string) (*Hook, error) {
 		name: name,
 		path: filepath.Join(repoPath, "hooks", name+".d", name),
 	}
-	isFile, err := util.IsFile(h.path)
-	if err != nil {
-		return nil, err
-	}
-	if isFile {
-		data, err := os.ReadFile(h.path)
-		if err != nil {
-			return nil, err
-		}
+	if data, err := os.ReadFile(h.path); err == nil {
 		h.IsActive = true
 		h.Content = string(data)
 		return h, nil
+	} else if !os.IsNotExist(err) {
+		return nil, err
 	}
 
 	samplePath := filepath.Join(repoPath, "hooks", name+".sample")
-	isFile, err = util.IsFile(samplePath)
-	if err != nil {
-		return nil, err
-	}
-	if isFile {
-		data, err := os.ReadFile(samplePath)
-		if err != nil {
-			return nil, err
-		}
+	if data, err := os.ReadFile(samplePath); err == nil {
 		h.Sample = string(data)
 	}
 	return h, nil

modules/setting/config_provider.go

@@ -202,11 +202,11 @@ func NewConfigProviderFromFile(file string) (ConfigProvider, error) {
 	loadedFromEmpty := true
 
 	if file != "" {
-		isFile, err := util.IsFile(file)
+		isExist, err := util.IsExist(file)
 		if err != nil {
-			return nil, fmt.Errorf("unable to check if %q is a file. Error: %v", file, err)
+			return nil, fmt.Errorf("unable to check if %q exists: %v", file, err)
 		}
-		if isFile {
+		if isExist {
 			if err = cfg.Append(file); err != nil {
 				return nil, fmt.Errorf("failed to load config file %q: %v", file, err)
 			}

modules/util/path.go

@@ -115,15 +115,10 @@ func IsDir(dir string) (bool, error) {
 	return false, err
 }
 
-// IsFile returns true if given path is a file,
-// or returns false when it's a directory or does not exist.
-func IsFile(filePath string) (bool, error) {
-	f, err := os.Stat(filePath)
+func IsRegularFile(filePath string) (bool, error) {
+	f, err := os.Lstat(filePath)
 	if err == nil {
-		return !f.IsDir(), nil
-	}
-	if os.IsNotExist(err) {
-		return false, nil
+		return f.Mode().IsRegular(), nil
 	}
 	return false, err
 }

routers/private/key.go

@@ -45,7 +45,7 @@ func UpdatePublicKeyInRepo(ctx *context.PrivateContext) {
 	ctx.PlainText(http.StatusOK, "success")
 }
 
-// AuthorizedPublicKeyByContent searches content as prefix (leak e-mail part)
+// AuthorizedPublicKeyByContent searches content as prefix (without comment part)
 // and returns public key found.
 func AuthorizedPublicKeyByContent(ctx *context.PrivateContext) {
 	content := ctx.FormString("content")
@@ -57,5 +57,14 @@ func AuthorizedPublicKeyByContent(ctx *context.PrivateContext) {
 		})
 		return
 	}
-	ctx.PlainText(http.StatusOK, publicKey.AuthorizedString())
+
+	authorizedString, err := asymkey_model.AuthorizedStringForKey(publicKey)
+	if err != nil {
+		ctx.JSON(http.StatusInternalServerError, private.Response{
+			Err:     err.Error(),
+			UserMsg: "invalid public key",
+		})
+		return
+	}
+	ctx.PlainText(http.StatusOK, authorizedString)
 }

services/asymkey/ssh_key_authorized_principals.go

@@ -25,10 +25,7 @@ import (
 // There is a dependence on the database within RewriteAllPrincipalKeys & RegeneratePrincipalKeys
 // The sshOpLocker is used from ssh_key_authorized_keys.go
 
-const (
-	authorizedPrincipalsFile = "authorized_principals"
-	tplCommentPrefix         = `# gitea public key`
-)
+const authorizedPrincipalsFile = "authorized_principals"
 
 // RewriteAllPrincipalKeys removes any authorized principal and rewrite all keys from database again.
 // Note: db.GetEngine(ctx).Iterate does not get latest data after insert/delete, so we have to call this function
@@ -90,10 +87,9 @@ func rewriteAllPrincipalKeys(ctx context.Context) error {
 	return util.Rename(tmpPath, fPath)
 }
 
-func regeneratePrincipalKeys(ctx context.Context, t io.StringWriter) error {
+func regeneratePrincipalKeys(ctx context.Context, t io.Writer) error {
 	if err := db.GetEngine(ctx).Where("type = ?", asymkey_model.KeyTypePrincipal).Iterate(new(asymkey_model.PublicKey), func(idx int, bean any) (err error) {
-		_, err = t.WriteString((bean.(*asymkey_model.PublicKey)).AuthorizedString())
-		return err
+		return asymkey_model.WriteAuthorizedStringForValidKey(bean.(*asymkey_model.PublicKey), t)
 	}); err != nil {
 		return err
 	}
@@ -114,11 +110,11 @@ func regeneratePrincipalKeys(ctx context.Context, t io.StringWriter) error {
 		scanner := bufio.NewScanner(f)
 		for scanner.Scan() {
 			line := scanner.Text()
-			if strings.HasPrefix(line, tplCommentPrefix) {
+			if strings.HasPrefix(line, asymkey_model.AuthorizedStringCommentPrefix) {
 				scanner.Scan()
 				continue
 			}
-			_, err = t.WriteString(line + "\n")
+			_, err = io.WriteString(t, line+"\n")
 			if err != nil {
 				return err
 			}

services/doctor/authorizedkeys.go

@@ -20,8 +20,6 @@ import (
 	asymkey_service "code.gitea.io/gitea/services/asymkey"
 )
 
-const tplCommentPrefix = `# gitea public key`
-
 func checkAuthorizedKeys(ctx context.Context, logger log.Logger, autofix bool) error {
 	if setting.SSH.StartBuiltinServer || !setting.SSH.CreateAuthorizedKeysFile {
 		return nil
@@ -47,7 +45,7 @@ func checkAuthorizedKeys(ctx context.Context, logger log.Logger, autofix bool) e
 	scanner := bufio.NewScanner(f)
 	for scanner.Scan() {
 		line := scanner.Text()
-		if strings.HasPrefix(line, tplCommentPrefix) {
+		if strings.HasPrefix(line, asymkey_model.AuthorizedStringCommentPrefix) {
 			continue
 		}
 		linesInAuthorizedKeys.Add(line)
@@ -67,7 +65,7 @@ func checkAuthorizedKeys(ctx context.Context, logger log.Logger, autofix bool) e
 	scanner = bufio.NewScanner(regenerated)
 	for scanner.Scan() {
 		line := scanner.Text()
-		if strings.HasPrefix(line, tplCommentPrefix) {
+		if strings.HasPrefix(line, asymkey_model.AuthorizedStringCommentPrefix) {
 			continue
 		}
 		if linesInAuthorizedKeys.Contains(line) {