On 06/08/2015 17:45, Ben Catterall wrote:
> Added trap handlers to catch exceptions such as a page fault, general
> protection fault, etc. These handlers will crash the domain as such exceptions
> would indicate that either there is a bug in deprivileged mode or it has been
> compromised by an attacker.
>
> Signed-off-by: Ben Catterall <[email protected]>
> ---
> xen/arch/x86/mm/hap/hap.c | 9 +++++++++
> xen/arch/x86/traps.c | 41 ++++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 49 insertions(+), 1 deletion(-)
>
> diff --git a/xen/arch/x86/mm/hap/hap.c b/xen/arch/x86/mm/hap/hap.c
> index abc5113..43bde89 100644
> --- a/xen/arch/x86/mm/hap/hap.c
> +++ b/xen/arch/x86/mm/hap/hap.c
> @@ -685,8 +685,17 @@ static int hap_page_fault(struct vcpu *v, unsigned long
> va,
> {
> struct domain *d = v->domain;
>
> + /* If we get a page fault whilst in HVM security user mode */
> + if( v->user_mode == 1 )
> + {
> + printk("HVM: #PF (%u:%u) whilst in user mode\n",
> + d->domain_id, v->vcpu_id);
%pv is your friend. Like Linux, we have custom printk formats. In this
case, passing 'v' as a parameter to %pv will cause d$Xv$Y to be
printed. (The example below predates %pv being introduced).
> + domain_crash_synchronous();
No need for _synchronous() here. _synchronous() should only be used
when you can't safely recover. It ends up spinning in a tight loop
waiting for the next timer interrupt, is anything up to 30ms away.
~Andrew
> + }
> +
> HAP_ERROR("Intercepted a guest #PF (%u:%u) with HAP enabled.\n",
> d->domain_id, v->vcpu_id);
> +
> domain_crash(d);
> return 0;
> }
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