On Thu, Nov 30, 2023 at 07:37:02PM +0100, Florian Weimer wrote: > * Tycho Andersen: > > > From: Tycho Andersen <tandersen@xxxxxxxxxxx> > > > > We are using the pidfd family of syscalls with the seccomp userspace > > notifier. When some thread triggers a seccomp notification, we want to do > > some things to its context (munge fd tables via pidfd_getfd(), maybe write > > to its memory, etc.). However, threads created with ~CLONE_FILES or > > ~CLONE_VM mean that we can't use the pidfd family of syscalls for this > > purpose, since their fd table or mm are distinct from the thread group > > leader's. In this patch, we relax this restriction for pidfd_open(). > > Does this mean that pidfd_getfd cannot currently be used to get > descriptors for a TID if that TID doesn't happen to share its descriptor > set with the thread group leader? Correct, that's what I'm trying to solve. > I'd like to offer a userspace API which allows safe stashing of > unreachable file descriptors on a service thread. By "safe" here do you mean not accessible via pidfd_getfd()? Tycho
