I think for setuid in particular the right fix is for the kernel to provide a new syscall that operates on the whole process. The current hoops that glibc has t

I think for setuid in particular the right fix is for the kernel to provide a new syscall that operates on the whole process. The current hoops that glibc has to jump through with signals are complicated (and maybe racy? it's been a while since I looked at the code) and tie up a signal for libc's private use; better support at the kernel layer would allow that to all be eventually dropped.