On Thu, Apr 17, 2014 at 12:38:36PM -0700, Andy Lutomirski wrote: > > I can't imagine any legitimate reason why an application of a particular > > ABI would want to try a syscall of another ABI, for example why an N64 > > process would want to call the O32 open(2) syscall. > > I've done it for testing. And x32 does it because it's x32. So from that perspective x32 isn't even a new ABI, just a castrated 64 bit app using the 64 bit ABI. > > For that reason I've long been contemplating to make syscalls of other ABIs > > unavailable, even without seccomp. Would that be useful for seccomp? > > It's still possible to execve something else. Would that other process then have a different syscall filter or is there only one global one? > > One exception though - I've seen a non-O32 application using syscall 4000, > > the indirect syscall syscall. Some needs to be the first to be taken out > > and shot ;-) > > > > Aargh. Let me guess: the indirect syscall syscall uses seven argument > registers. I guess ARM wasn't the only architecture to make the > mistake of having one of those :( Yes, seven arguments. The sole reason why MIPS has an indirect syscall is that I followed the the example of earlier MIPS UNIX variants. And it has interesting issues such as with 64 bit arguments on 32 bit machines. Ralf
