Re: Syscall table AKA hijacking syscalls

Libor Vanek
2004-01-02T23:47:06Z

>>I'm writing some project which needs to hijack some syscalls in VFS
>>layer. AFAIK in 2.6 is this "not-wanted" solution (even that there are
>>some very nasty ways of doing it - see
>>http://mail.nl.linux.org/kernelnewbies/2002-12/msg00266.html )
>
>
> And it will fail miserably on many non x86 architectures for
> various reasons:
>
> 1. ppc64 and ia64 use function descriptors
> 2. sparc64 uses a 32bit call out table
>
> In short its not only an awful hack, its horribly non portable :)

But in short you always get some syscall from userspace and have some table with function vectors assigned to each syscall, don't you?

So you can have something like "append_this_function_before_syscall_sys_open" and "append_this_function_after_syscall_sys_open" which would be platform independent but will have platform dependent implementation.

--

Libor Vanek