[PATCH 10/10] KVM: Log ROE violations in system log

From: Ahmed Abd El Mawgood <ahmedsoliman@mena.vt.edu>
To: Paolo Bonzini <pbonzini@redhat.com>,
	rkrcmar@redhat.com, Jonathan Corbet <corbet@lwn.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	hpa@zytor.com, x86@kernel.org, kvm@vger.kernel.org,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	ahmedsoliman0x666@gmail.com, ovich00@gmail.com,
	kernel-hardening@lists.openwall.com, nigel.edwards@hpe.com,
	Boris Lukashev <blukashev@sempervictus.com>,
	Igor Stoppa <igor.stoppa@gmail.com>
Cc: Ahmed Abd El Mawgood <ahmedsoliman@mena.vt.edu>
Subject: [PATCH 10/10] KVM: Log ROE violations in system log
Date: Fri,  7 Dec 2018 14:48:03 +0200	[thread overview]
Message-ID: <20181207124803.10828-11-ahmedsoliman@mena.vt.edu> (raw)
In-Reply-To: <20181207124803.10828-1-ahmedsoliman@mena.vt.edu>

Signed-off-by: Ahmed Abd El Mawgood <ahmedsoliman@mena.vt.edu>
---
 virt/kvm/kvm_main.c    |  5 +++++
 virt/kvm/roe.c         | 14 ++++++++++++++
 virt/kvm/roe_generic.h |  2 +-
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index c3a21d3bc8..661933053f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1870,6 +1870,7 @@ static u64 roe_gfn_to_hva(struct kvm_memory_slot *slot, gfn_t gfn, int offset,
 	addr = __gfn_to_hva_many(slot, gfn, NULL, false);
 	return addr;
 }
+
 static int __kvm_write_guest_page(struct kvm_memory_slot *memslot, gfn_t gfn,
 			          const void *data, int offset, int len)
 {
@@ -1877,6 +1878,10 @@ static int __kvm_write_guest_page(struct kvm_memory_slot *memslot, gfn_t gfn,
 	unsigned long addr;
 
 	addr = roe_gfn_to_hva(memslot, gfn, offset, len);
+	if (gfn_is_full_roe(memslot, gfn) ||
+			kvm_roe_check_range(memslot, gfn, offset, len))
+		kvm_warning_roe_violation((gfn << PAGE_SHIFT) + offset, data,
+				len);
 	if (kvm_is_error_hva(addr))
 		return -EFAULT;
 	r = __copy_to_user((void __user *)addr + offset, data, len);
diff --git a/virt/kvm/roe.c b/virt/kvm/roe.c
index 6555838f0c..36b85fb303 100644
--- a/virt/kvm/roe.c
+++ b/virt/kvm/roe.c
@@ -76,6 +76,20 @@ void kvm_roe_free(struct kvm_memory_slot *slot)
 	kvfree(slot->prot_list);
 }
 
+void kvm_warning_roe_violation(u64 addr, const void *data, int len)
+{
+	int i;
+	const char *d = data;
+	char *buf = kvmalloc(len * 3 + 1, GFP_KERNEL);
+
+	for (i = 0; i < len; i++)
+		sprintf(buf+3*i, " %02x", d[i]);
+	pr_warn("ROE violation:\n");
+	pr_warn("\tAttempt to write %d bytes at address 0x%08llx\n", len, addr);
+	pr_warn("\tData: %s\n", buf);
+	kvfree(buf);
+}
+
 static void kvm_roe_protect_slot(struct kvm *kvm, struct kvm_memory_slot *slot,
 		gfn_t gfn, u64 npages, bool partial)
 {
diff --git a/virt/kvm/roe_generic.h b/virt/kvm/roe_generic.h
index f1ce4a8aec..8c191362cd 100644
--- a/virt/kvm/roe_generic.h
+++ b/virt/kvm/roe_generic.h
@@ -14,5 +14,5 @@ void kvm_roe_free(struct kvm_memory_slot *slot);
 int kvm_roe_init(struct kvm_memory_slot *slot);
 bool kvm_roe_check_range(struct kvm_memory_slot *slot, gfn_t gfn, int offset,
 		int len);
-
+void kvm_warning_roe_violation(u64 addr, const void *data, int len);
 #endif
-- 
2.19.2

