On Thu, 6 Jul 2006 16:46:40 -0400 Daniel Serpell <[EMAIL PROTECTED]> wrote:
> But there is a way to detect virtual machines under x86, see > http://invisiblethings.org/papers/redpill.html > > But if you run qemu without direct instruction copying, it won't > work (and qemu will run slower), because qemu will correctly > emulate the unprivileged instructions. Out of interest, sidt returns limit:base 07ff:c0372000 on my host, and 07ff:f0050000 on a linux guest with kqemu, and 07ff:c04b5000 on the same linux guest without kqemu, which illustrates the point. I used the following code: #include <stdio.h> int main(int argc, char **argv) { unsigned char idtr[6]; __asm__ ("sidt %0" : "=m" (*&idtr)); fprintf(stdout, "IDTR: limit %2.2x%2.2x base %2.2x%2.2x%2.2x%2.2x\n", idtr[1],idtr[0],idtr[5],idtr[4],idtr[3],idtr[2]); } which doesn't need executable heap (my kernel is PaX-enabled), unlike the redpill version, but is gcc-specific. -- Kevin F. Quinn
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