aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorJan Kiszka <jan.kiszka@siemens.com>2009-08-03 18:43:28 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2009-09-24 08:44:07 -0700
commitbe45e259c6948bed4482d9b9de32236078db2443 (patch)
treebb1d0dcfd238008a22d334b916a90948528d7d67
parent6aece86ef27f5713f7a34a3e4c844ad0ba29fbae (diff)
downloadlinux-linaro-stable-be45e259c6948bed4482d9b9de32236078db2443.tar.gz
KVM: x86: Disallow hypercalls for guest callers in rings > 0
commit 07708c4af1346ab1521b26a202f438366b7bcffd upstream. So far unprivileged guest callers running in ring 3 can issue, e.g., MMU hypercalls. Normally, such callers cannot provide any hand-crafted MMU command structure as it has to be passed by its physical address, but they can still crash the guest kernel by passing random addresses. To close the hole, this patch considers hypercalls valid only if issued from guest ring 0. This may still be relaxed on a per-hypercall base in the future once required. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Avi Kivity <avi@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--arch/x86/kvm/x86.c6
-rw-r--r--include/linux/kvm_para.h1
2 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 978fcbe10693..3d360455fa24 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2911,6 +2911,11 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
a3 &= 0xFFFFFFFF;
}
+ if (kvm_x86_ops->get_cpl(vcpu) != 0) {
+ ret = -KVM_EPERM;
+ goto out;
+ }
+
switch (nr) {
case KVM_HC_VAPIC_POLL_IRQ:
ret = 0;
@@ -2922,6 +2927,7 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
ret = -KVM_ENOSYS;
break;
}
+out:
kvm_register_write(vcpu, VCPU_REGS_RAX, ret);
++vcpu->stat.hypercalls;
return r;
diff --git a/include/linux/kvm_para.h b/include/linux/kvm_para.h
index 3ddce03766ca..d73109243fda 100644
--- a/include/linux/kvm_para.h
+++ b/include/linux/kvm_para.h
@@ -13,6 +13,7 @@
#define KVM_ENOSYS 1000
#define KVM_EFAULT EFAULT
#define KVM_E2BIG E2BIG
+#define KVM_EPERM EPERM
#define KVM_HC_VAPIC_POLL_IRQ 1
#define KVM_HC_MMU_OP 2