1 files changed, 275 insertions, 0 deletions

diff --git a/arch/x86/kvm/vmx/sgx.c b/arch/x86/kvm/vmx/sgx.c
index d874eb180b7d..2cf9d7cf818c 100644
--- a/arch/x86/kvm/vmx/sgx.c
+++ b/arch/x86/kvm/vmx/sgx.c
@@ -11,6 +11,279 @@
 
 bool __read_mostly enable_sgx;
 
+/*
+ * ENCLS's memory operands use a fixed segment (DS) and a fixed
+ * address size based on the mode.  Related prefixes are ignored.
+ */
+static int sgx_get_encls_gva(struct kvm_vcpu *vcpu, unsigned long offset,
+			     int size, int alignment, gva_t *gva)
+{
+	struct kvm_segment s;
+	bool fault;
+
+	/* Skip vmcs.GUEST_DS retrieval for 64-bit mode to avoid VMREADs. */
+	*gva = offset;
+	if (!is_long_mode(vcpu)) {
+		vmx_get_segment(vcpu, &s, VCPU_SREG_DS);
+		*gva += s.base;
+	}
+
+	if (!IS_ALIGNED(*gva, alignment)) {
+		fault = true;
+	} else if (likely(is_long_mode(vcpu))) {
+		fault = is_noncanonical_address(*gva, vcpu);
+	} else {
+		*gva &= 0xffffffff;
+		fault = (s.unusable) ||
+			(s.type != 2 && s.type != 3) ||
+			(*gva > s.limit) ||
+			((s.base != 0 || s.limit != 0xffffffff) &&
+			(((u64)*gva + size - 1) > s.limit + 1));
+	}
+	if (fault)
+		kvm_inject_gp(vcpu, 0);
+	return fault ? -EINVAL : 0;
+}
+
+static void sgx_handle_emulation_failure(struct kvm_vcpu *vcpu, u64 addr,
+					 unsigned int size)
+{
+	vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+	vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
+	vcpu->run->internal.ndata = 2;
+	vcpu->run->internal.data[0] = addr;
+	vcpu->run->internal.data[1] = size;
+}
+
+static int sgx_read_hva(struct kvm_vcpu *vcpu, unsigned long hva, void *data,
+			unsigned int size)
+{
+	if (__copy_from_user(data, (void __user *)hva, size)) {
+		sgx_handle_emulation_failure(vcpu, hva, size);
+		return -EFAULT;
+	}
+
+	return 0;
+}
+
+static int sgx_gva_to_gpa(struct kvm_vcpu *vcpu, gva_t gva, bool write,
+			  gpa_t *gpa)
+{
+	struct x86_exception ex;
+
+	if (write)
+		*gpa = kvm_mmu_gva_to_gpa_write(vcpu, gva, &ex);
+	else
+		*gpa = kvm_mmu_gva_to_gpa_read(vcpu, gva, &ex);
+
+	if (*gpa == UNMAPPED_GVA) {
+		kvm_inject_emulated_page_fault(vcpu, &ex);
+		return -EFAULT;
+	}
+
+	return 0;
+}
+
+static int sgx_gpa_to_hva(struct kvm_vcpu *vcpu, gpa_t gpa, unsigned long *hva)
+{
+	*hva = kvm_vcpu_gfn_to_hva(vcpu, PFN_DOWN(gpa));
+	if (kvm_is_error_hva(*hva)) {
+		sgx_handle_emulation_failure(vcpu, gpa, 1);
+		return -EFAULT;
+	}
+
+	*hva |= gpa & ~PAGE_MASK;
+
+	return 0;
+}
+
+static int sgx_inject_fault(struct kvm_vcpu *vcpu, gva_t gva, int trapnr)
+{
+	struct x86_exception ex;
+
+	/*
+	 * A non-EPCM #PF indicates a bad userspace HVA.  This *should* check
+	 * for PFEC.SGX and not assume any #PF on SGX2 originated in the EPC,
+	 * but the error code isn't (yet) plumbed through the ENCLS helpers.
+	 */
+	if (trapnr == PF_VECTOR && !boot_cpu_has(X86_FEATURE_SGX2)) {
+		vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+		vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
+		vcpu->run->internal.ndata = 0;
+		return 0;
+	}
+
+	/*
+	 * If the guest thinks it's running on SGX2 hardware, inject an SGX
+	 * #PF if the fault matches an EPCM fault signature (#GP on SGX1,
+	 * #PF on SGX2).  The assumption is that EPCM faults are much more
+	 * likely than a bad userspace address.
+	 */
+	if ((trapnr == PF_VECTOR || !boot_cpu_has(X86_FEATURE_SGX2)) &&
+	    guest_cpuid_has(vcpu, X86_FEATURE_SGX2)) {
+		memset(&ex, 0, sizeof(ex));
+		ex.vector = PF_VECTOR;
+		ex.error_code = PFERR_PRESENT_MASK | PFERR_WRITE_MASK |
+				PFERR_SGX_MASK;
+		ex.address = gva;
+		ex.error_code_valid = true;
+		ex.nested_page_fault = false;
+		kvm_inject_page_fault(vcpu, &ex);
+	} else {
+		kvm_inject_gp(vcpu, 0);
+	}
+	return 1;
+}
+
+static int __handle_encls_ecreate(struct kvm_vcpu *vcpu,
+				  struct sgx_pageinfo *pageinfo,
+				  unsigned long secs_hva,
+				  gva_t secs_gva)
+{
+	struct sgx_secs *contents = (struct sgx_secs *)pageinfo->contents;
+	struct kvm_cpuid_entry2 *sgx_12_0, *sgx_12_1;
+	u64 attributes, xfrm, size;
+	u32 miscselect;
+	u8 max_size_log2;
+	int trapnr, ret;
+
+	sgx_12_0 = kvm_find_cpuid_entry(vcpu, 0x12, 0);
+	sgx_12_1 = kvm_find_cpuid_entry(vcpu, 0x12, 1);
+	if (!sgx_12_0 || !sgx_12_1) {
+		vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+		vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
+		vcpu->run->internal.ndata = 0;
+		return 0;
+	}
+
+	miscselect = contents->miscselect;
+	attributes = contents->attributes;
+	xfrm = contents->xfrm;
+	size = contents->size;
+
+	/* Enforce restriction of access to the PROVISIONKEY. */
+	if (!vcpu->kvm->arch.sgx_provisioning_allowed &&
+	    (attributes & SGX_ATTR_PROVISIONKEY)) {
+		if (sgx_12_1->eax & SGX_ATTR_PROVISIONKEY)
+			pr_warn_once("KVM: SGX PROVISIONKEY advertised but not allowed\n");
+		kvm_inject_gp(vcpu, 0);
+		return 1;
+	}
+
+	/* Enforce CPUID restrictions on MISCSELECT, ATTRIBUTES and XFRM. */
+	if ((u32)miscselect & ~sgx_12_0->ebx ||
+	    (u32)attributes & ~sgx_12_1->eax ||
+	    (u32)(attributes >> 32) & ~sgx_12_1->ebx ||
+	    (u32)xfrm & ~sgx_12_1->ecx ||
+	    (u32)(xfrm >> 32) & ~sgx_12_1->edx) {
+		kvm_inject_gp(vcpu, 0);
+		return 1;
+	}
+
+	/* Enforce CPUID restriction on max enclave size. */
+	max_size_log2 = (attributes & SGX_ATTR_MODE64BIT) ? sgx_12_0->edx >> 8 :
+							    sgx_12_0->edx;
+	if (size >= BIT_ULL(max_size_log2))
+		kvm_inject_gp(vcpu, 0);
+
+	/*
+	 * sgx_virt_ecreate() returns:
+	 *  1) 0:	ECREATE was successful
+	 *  2) -EFAULT:	ECREATE was run but faulted, and trapnr was set to the
+	 *		exception number.
+	 *  3) -EINVAL:	access_ok() on @secs_hva failed. This should never
+	 *		happen as KVM checks host addresses at memslot creation.
+	 *		sgx_virt_ecreate() has already warned in this case.
+	 */
+	ret = sgx_virt_ecreate(pageinfo, (void __user *)secs_hva, &trapnr);
+	if (!ret)
+		return kvm_skip_emulated_instruction(vcpu);
+	if (ret == -EFAULT)
+		return sgx_inject_fault(vcpu, secs_gva, trapnr);
+
+	return ret;
+}
+
+static int handle_encls_ecreate(struct kvm_vcpu *vcpu)
+{
+	gva_t pageinfo_gva, secs_gva;
+	gva_t metadata_gva, contents_gva;
+	gpa_t metadata_gpa, contents_gpa, secs_gpa;
+	unsigned long metadata_hva, contents_hva, secs_hva;
+	struct sgx_pageinfo pageinfo;
+	struct sgx_secs *contents;
+	struct x86_exception ex;
+	int r;
+
+	if (sgx_get_encls_gva(vcpu, kvm_rbx_read(vcpu), 32, 32, &pageinfo_gva) ||
+	    sgx_get_encls_gva(vcpu, kvm_rcx_read(vcpu), 4096, 4096, &secs_gva))
+		return 1;
+
+	/*
+	 * Copy the PAGEINFO to local memory, its pointers need to be
+	 * translated, i.e. we need to do a deep copy/translate.
+	 */
+	r = kvm_read_guest_virt(vcpu, pageinfo_gva, &pageinfo,
+				sizeof(pageinfo), &ex);
+	if (r == X86EMUL_PROPAGATE_FAULT) {
+		kvm_inject_emulated_page_fault(vcpu, &ex);
+		return 1;
+	} else if (r != X86EMUL_CONTINUE) {
+		sgx_handle_emulation_failure(vcpu, pageinfo_gva,
+					     sizeof(pageinfo));
+		return 0;
+	}
+
+	if (sgx_get_encls_gva(vcpu, pageinfo.metadata, 64, 64, &metadata_gva) ||
+	    sgx_get_encls_gva(vcpu, pageinfo.contents, 4096, 4096,
+			      &contents_gva))
+		return 1;
+
+	/*
+	 * Translate the SECINFO, SOURCE and SECS pointers from GVA to GPA.
+	 * Resume the guest on failure to inject a #PF.
+	 */
+	if (sgx_gva_to_gpa(vcpu, metadata_gva, false, &metadata_gpa) ||
+	    sgx_gva_to_gpa(vcpu, contents_gva, false, &contents_gpa) ||
+	    sgx_gva_to_gpa(vcpu, secs_gva, true, &secs_gpa))
+		return 1;
+
+	/*
+	 * ...and then to HVA.  The order of accesses isn't architectural, i.e.
+	 * KVM doesn't have to fully process one address at a time.  Exit to
+	 * userspace if a GPA is invalid.
+	 */
+	if (sgx_gpa_to_hva(vcpu, metadata_gpa, &metadata_hva) ||
+	    sgx_gpa_to_hva(vcpu, contents_gpa, &contents_hva) ||
+	    sgx_gpa_to_hva(vcpu, secs_gpa, &secs_hva))
+		return 0;
+
+	/*
+	 * Copy contents into kernel memory to prevent TOCTOU attack. E.g. the
+	 * guest could do ECREATE w/ SECS.SGX_ATTR_PROVISIONKEY=0, and
+	 * simultaneously set SGX_ATTR_PROVISIONKEY to bypass the check to
+	 * enforce restriction of access to the PROVISIONKEY.
+	 */
+	contents = (struct sgx_secs *)__get_free_page(GFP_KERNEL_ACCOUNT);
+	if (!contents)
+		return -ENOMEM;
+
+	/* Exit to userspace if copying from a host userspace address fails. */
+	if (sgx_read_hva(vcpu, contents_hva, (void *)contents, PAGE_SIZE)) {
+		free_page((unsigned long)contents);
+		return 0;
+	}
+
+	pageinfo.metadata = metadata_hva;
+	pageinfo.contents = (u64)contents;
+
+	r = __handle_encls_ecreate(vcpu, &pageinfo, secs_hva, secs_gva);
+
+	free_page((unsigned long)contents);
+
+	return r;
+}
+
 static inline bool encls_leaf_enabled_in_guest(struct kvm_vcpu *vcpu, u32 leaf)
 {
 	if (!enable_sgx || !guest_cpuid_has(vcpu, X86_FEATURE_SGX))
@@ -41,6 +314,8 @@ int handle_encls(struct kvm_vcpu *vcpu)
 	} else if (!sgx_enabled_in_guest_bios(vcpu)) {
 		kvm_inject_gp(vcpu, 0);
 	} else {
+		if (leaf == ECREATE)
+			return handle_encls_ecreate(vcpu);
 		WARN(1, "KVM: unexpected exit on ENCLS[%u]", leaf);
 		vcpu->run->exit_reason = KVM_EXIT_UNKNOWN;
 		vcpu->run->hw.hardware_exit_reason = EXIT_REASON_ENCLS;