On Fri, Nov 09, 2018 at 08:02:14PM +0000, Michael Tirado wrote: [...] > > > That aside: I wonder whether a better API would be something that > > > allows you to create a new readonly file descriptor, instead of > > > fiddling with the writability of an existing fd. > > > > Every now and then I try to write a patch to prevent using proc to reopen > > a file with greater permission than the original open. > > > > I like your idea to have a clean way to reopen a a memfd with reduced > > permissions. But I would make it a syscall instead and maybe make it only > > work for memfd at first. And the proc issue would need to be fixed, too. > > IMO the best solution would handle the issue at memfd creation time by > removing the race condition. I agree, this is another idea I'm exploring. We could add a new .open callback to shmem_file_operations and check for seals there. thanks, - Joel
