Re: [PATCH] linux-2.5.43_vsyscall_A0

Pavel Machek
2002-10-26T10:26:49Z

Hi!

> > Guess you'll have some problems then with UML on x86-64, which always
> > uses vgettimeofday. But it's only used for gettimeofday() currently,
> > perhaps it's not that bad when the UML child runs with the host's
> > time.
>
> It's not horrible, but it's still broken. There are people who depend
> on UML being able to keep its own time separately from the host.
>
> > I guess it would be possible to add some support for UML to map own
> > code over the vsyscall reserved locations. UML would need to use the
> > syscalls then. But it'll be likely ugly.
>
> Yeah, it would be.
>
> My preferred solution would be for libc to ask the kernel where the vsyscall
> area is. That's reasonably clean and virtualizable. Andrea doesn't like it
> because it adds a few instructions to the vsyscall address calculation.

But sandboxed application could still "guess" where vsyscall address
is and get the data it is not supposed to get, right?
Pavel
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