On Tue, May 19, 2020 at 12:39:39AM +0200, Jann Horn wrote: > > For user_notif, I think we need something in and around these options: > > > > - make a new API that explicitly follows EA struct design > > (and while read()/write() might be easier[4], I tend to agree with > > Jann and we need to stick to ioctl(): as Tycho noted, "read/write is > > for data". Though I wonder if read() could be used for the notifications, > > which ARE data, and use ioctl() for the responses?) > > Just as a note: If we use read() there, we'll never be able to > transfer things like FDs through that API. > Although there is no good reason for read being able to receive FDs, there is precedence for recvmsg being able to do this. Either way, I do not think it's a good idea to recv file descriptors, and instead file descriptors should be fetched via the pidfd_getfd syscall. Injection is more complicated, and for now, I believe that "writes" should be done via ioctl, or in the future, something like sendmsg might work.
