On Fri, Jul 10, 2015 at 08:24:41PM +0200, Richard Weinberger wrote: > Am 10.07.2015 um 18:17 schrieb Eric W. Biederman: > > > > Today proc and sysfs do not contain any executable files. Several > > applications today mount proc or sysfs without noexec and nosuid and > > then depend on there being no exectuables files on proc or sysfs. > > Having any executable files show on proc or sysfs would cause > > a user space visible regression, and most likely security problems. > > > > Therefore commit to never allowing executables on proc and sysfs by > > adding a new flag to mark them as filesystems without executables and > > enforce that flag. > > > > Test the flag where MNT_NOEXEC is tested today, so that the only user > > visible effect will be that exectuables will be treated as if the > > execute bit is cleared. > > > > The filesystems proc and sysfs do not currently incoporate any > > executable files so this does not result in any user visible effects. > > > > This makes it unnecessary to vet changes to proc and sysfs tightly for > > adding exectuable files or changes to chattr that would modify > > existing files, as no matter what the individual file say they will > > not be treated as exectuable files by the vfs. > > > > Not having to vet changes to closely is important as without this we > > are only one proc_create call (or another goof up in the > > implementation of notify_change) from having problematic executables > > on proc. Those mistakes are all too easy to make and would create > > a situation where there are security issues or the assumptions of > > some program having to be broken (and cause userspace regressions). > > Would it make sense to add SB_I_NOEXEC to more pseudo filesystems? > Say pstore or devpts? And configfs and cgroupfs? -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
