xattr: return EOPNOTSUPP instead of ENODATA in GetXattr

Reading system.posix_acl_access and system.posix_acl_default
should return EOPNOTSUPP to inform user-space that we do not
support ACLs.

xftestest essientially does

	chacl -l | grep "Operation not supported"

to determine if the filesystem supports ACLs, and used to
wrongly believe that gocryptfs does.

1 files changed, 4 insertions, 5 deletions

diff --git a/internal/fusefrontend/xattr.go b/internal/fusefrontend/xattr.go
index 9300fe8..2bbdf41 100644
--- a/internal/fusefrontend/xattr.go
+++ b/internal/fusefrontend/xattr.go
@@ -13,7 +13,10 @@ import (
 	"github.com/rfjakob/gocryptfs/internal/tlog"
 )
 
+const _EOPNOTSUPP = fuse.Status(syscall.EOPNOTSUPP)
+
 // xattr names are encrypted like file names, but with a fixed IV.
+// Padded with "_xx" for length 16.
 var xattrNameIV = []byte("xattr_name_iv_xx")
 
 // We store encrypted xattrs under this prefix plus the base64-encoded
@@ -27,9 +30,7 @@ func (fs *FS) GetXAttr(path string, attr string, context *fuse.Context) ([]byte,
 		return nil, fuse.EPERM
 	}
 	if disallowedXAttrName(attr) {
-		// "ls -l" queries security.selinux, system.posix_acl_access, system.posix_acl_default
-		// and throws error messages if it gets something else than ENODATA.
-		return nil, fuse.ENODATA
+		return nil, _EOPNOTSUPP
 	}
 	cAttr := fs.encryptXattrName(attr)
 	cPath, err := fs.getBackingPath(path)
@@ -48,8 +49,6 @@ func (fs *FS) GetXAttr(path string, attr string, context *fuse.Context) ([]byte,
 	return data, fuse.OK
 }
 
-const _EOPNOTSUPP = fuse.Status(syscall.EOPNOTSUPP)
-
 // SetXAttr implements pathfs.Filesystem.
 func (fs *FS) SetXAttr(path string, attr string, data []byte, flags int, context *fuse.Context) fuse.Status {
 	if fs.isFiltered(path) {