> From: "Theo de Raadt" <dera...@openbsd.org> > Date: Sat, 22 Jun 2024 06:16:03 -0600 > > Mark Kettenis <mark.kette...@xs4all.nl> wrote: > > > Theo pointed out the NOBTCFI reversal here. Now the reason that we > > still see SIGILL despite fixes to the assembly code is because the > > -mbranch-protection=pac-ret option added by the configure script > > actually downgrades our default of enabling both BTI and PAC to just > > enabling PAC. So the necessary BTI instructrions were missing from > > the C code. > > How did this issue arise? Is PAC without BTI the case on MacOS?
Well, M1 did have PAC but no BTI. BTI only came with M2. > > With the diff below things seem to work fine on Apple M2. There is > > one failure in the testsuite: > > 1) Failure: > > TestIO_Console#test_failed_path > > [/home/ports/pobj/ruby-3.3.3/ruby-3.3.3/test/io/console/test_io_console.rb:46]: > > [Errno::ENODEV, Errno::ENOTTY, Errno::EBADF, Errno::ENXIO] exception > > expected, not #<Errno::EOPNOTSUPP: Operation not supported - /dev/null>. > > > > but I'm pretty sure that is unrelated to BTI support. > > I suspect that's the recent delution over "isatty is poorly standardized, > and we believe it should return linux errno". Not sure if it isatty(3), but it is related to an ioctl on /dev/null. And we have a problem in OpenBSD here. On amd64, the mmioctl() function returns ENODEV for unimplemented ioctls. And this is one of the values that ruby expects. But on most other architectures mmioctl() return EOPNOTSUPP. I think that's a bug introduced 23 years ago by christos when an MI mmioctl() was introduced in NetBSD that got somehow copied into our MD variants of mmioctl(). That said, I think the actual correct return value should be ENOTTY is that is what our man page and POSIX say. And that would probably fix isatty(3) as well, which according to the man page should return ENOTTY if the file descriptor isn't associated with a terminal. This is what modern FreeBSD does.
