On Tue, Jun 4, 2019 at 1:39 PM David Howells <dhowells@xxxxxxxxxx> wrote: > > Andy Lutomirski <luto@xxxxxxxxxx> wrote: > > > > Here's a set of patches to add a general variable-length notification queue > > > concept and to add sources of events for: > > > > I asked before and didn't see a response, so I'll ask again. Why are you > > paying any attention at all to the creds that generate an event? > > Casey responded to you. It's one of his requirements. > It being a "requirement" doesn't make it okay. > However, the LSMs (or at least SELinux) ignore f_cred and use current_cred() > when checking permissions. See selinux_revalidate_file_permission() for > example - it uses current_cred() not file->f_cred to re-evaluate the perms, > and the fd might be shared between a number of processes with different creds. That's a bug. It's arguably a rather severe bug. If I ever get around to writing the patch I keep thinking of that will warn if we use creds from invalid contexts, it will warn. Let's please not repeat this.
