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-rw-r--r--arch/x86/kvm/vmx/sgx.c502
1 files changed, 502 insertions, 0 deletions
diff --git a/arch/x86/kvm/vmx/sgx.c b/arch/x86/kvm/vmx/sgx.c
new file mode 100644
index 000000000000..6693ebdc0770
--- /dev/null
+++ b/arch/x86/kvm/vmx/sgx.c
@@ -0,0 +1,502 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright(c) 2021 Intel Corporation. */
+
+#include <asm/sgx.h>
+
+#include "cpuid.h"
+#include "kvm_cache_regs.h"
+#include "nested.h"
+#include "sgx.h"
+#include "vmx.h"
+#include "x86.h"
+
+bool __read_mostly enable_sgx = 1;
+module_param_named(sgx, enable_sgx, bool, 0444);
+
+/* Initial value of guest's virtual SGX_LEPUBKEYHASHn MSRs */
+static u64 sgx_pubkey_hash[4] __ro_after_init;
+
+/*
+ * 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 int handle_encls_einit(struct kvm_vcpu *vcpu)
+{
+ unsigned long sig_hva, secs_hva, token_hva, rflags;
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+ gva_t sig_gva, secs_gva, token_gva;
+ gpa_t sig_gpa, secs_gpa, token_gpa;
+ int ret, trapnr;
+
+ if (sgx_get_encls_gva(vcpu, kvm_rbx_read(vcpu), 1808, 4096, &sig_gva) ||
+ sgx_get_encls_gva(vcpu, kvm_rcx_read(vcpu), 4096, 4096, &secs_gva) ||
+ sgx_get_encls_gva(vcpu, kvm_rdx_read(vcpu), 304, 512, &token_gva))
+ return 1;
+
+ /*
+ * Translate the SIGSTRUCT, SECS and TOKEN pointers from GVA to GPA.
+ * Resume the guest on failure to inject a #PF.
+ */
+ if (sgx_gva_to_gpa(vcpu, sig_gva, false, &sig_gpa) ||
+ sgx_gva_to_gpa(vcpu, secs_gva, true, &secs_gpa) ||
+ sgx_gva_to_gpa(vcpu, token_gva, false, &token_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. Note, all structures are aligned and
+ * cannot split pages.
+ */
+ if (sgx_gpa_to_hva(vcpu, sig_gpa, &sig_hva) ||
+ sgx_gpa_to_hva(vcpu, secs_gpa, &secs_hva) ||
+ sgx_gpa_to_hva(vcpu, token_gpa, &token_hva))
+ return 0;
+
+ ret = sgx_virt_einit((void __user *)sig_hva, (void __user *)token_hva,
+ (void __user *)secs_hva,
+ vmx->msr_ia32_sgxlepubkeyhash, &trapnr);
+
+ if (ret == -EFAULT)
+ return sgx_inject_fault(vcpu, secs_gva, trapnr);
+
+ /*
+ * sgx_virt_einit() returns -EINVAL when access_ok() fails on @sig_hva,
+ * @token_hva or @secs_hva. This should never happen as KVM checks host
+ * addresses at memslot creation. sgx_virt_einit() has already warned
+ * in this case, so just return.
+ */
+ if (ret < 0)
+ return ret;
+
+ rflags = vmx_get_rflags(vcpu) & ~(X86_EFLAGS_CF | X86_EFLAGS_PF |
+ X86_EFLAGS_AF | X86_EFLAGS_SF |
+ X86_EFLAGS_OF);
+ if (ret)
+ rflags |= X86_EFLAGS_ZF;
+ else
+ rflags &= ~X86_EFLAGS_ZF;
+ vmx_set_rflags(vcpu, rflags);
+
+ kvm_rax_write(vcpu, ret);
+ return kvm_skip_emulated_instruction(vcpu);
+}
+
+static inline bool encls_leaf_enabled_in_guest(struct kvm_vcpu *vcpu, u32 leaf)
+{
+ if (!enable_sgx || !guest_cpuid_has(vcpu, X86_FEATURE_SGX))
+ return false;
+
+ if (leaf >= ECREATE && leaf <= ETRACK)
+ return guest_cpuid_has(vcpu, X86_FEATURE_SGX1);
+
+ if (leaf >= EAUG && leaf <= EMODT)
+ return guest_cpuid_has(vcpu, X86_FEATURE_SGX2);
+
+ return false;
+}
+
+static inline bool sgx_enabled_in_guest_bios(struct kvm_vcpu *vcpu)
+{
+ const u64 bits = FEAT_CTL_SGX_ENABLED | FEAT_CTL_LOCKED;
+
+ return (to_vmx(vcpu)->msr_ia32_feature_control & bits) == bits;
+}
+
+int handle_encls(struct kvm_vcpu *vcpu)
+{
+ u32 leaf = (u32)kvm_rax_read(vcpu);
+
+ if (!encls_leaf_enabled_in_guest(vcpu, leaf)) {
+ kvm_queue_exception(vcpu, UD_VECTOR);
+ } else if (!sgx_enabled_in_guest_bios(vcpu)) {
+ kvm_inject_gp(vcpu, 0);
+ } else {
+ if (leaf == ECREATE)
+ return handle_encls_ecreate(vcpu);
+ if (leaf == EINIT)
+ return handle_encls_einit(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;
+ return 0;
+ }
+ return 1;
+}
+
+void setup_default_sgx_lepubkeyhash(void)
+{
+ /*
+ * Use Intel's default value for Skylake hardware if Launch Control is
+ * not supported, i.e. Intel's hash is hardcoded into silicon, or if
+ * Launch Control is supported and enabled, i.e. mimic the reset value
+ * and let the guest write the MSRs at will. If Launch Control is
+ * supported but disabled, then use the current MSR values as the hash
+ * MSRs exist but are read-only (locked and not writable).
+ */
+ if (!enable_sgx || boot_cpu_has(X86_FEATURE_SGX_LC) ||
+ rdmsrl_safe(MSR_IA32_SGXLEPUBKEYHASH0, &sgx_pubkey_hash[0])) {
+ sgx_pubkey_hash[0] = 0xa6053e051270b7acULL;
+ sgx_pubkey_hash[1] = 0x6cfbe8ba8b3b413dULL;
+ sgx_pubkey_hash[2] = 0xc4916d99f2b3735dULL;
+ sgx_pubkey_hash[3] = 0xd4f8c05909f9bb3bULL;
+ } else {
+ /* MSR_IA32_SGXLEPUBKEYHASH0 is read above */
+ rdmsrl(MSR_IA32_SGXLEPUBKEYHASH1, sgx_pubkey_hash[1]);
+ rdmsrl(MSR_IA32_SGXLEPUBKEYHASH2, sgx_pubkey_hash[2]);
+ rdmsrl(MSR_IA32_SGXLEPUBKEYHASH3, sgx_pubkey_hash[3]);
+ }
+}
+
+void vcpu_setup_sgx_lepubkeyhash(struct kvm_vcpu *vcpu)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+
+ memcpy(vmx->msr_ia32_sgxlepubkeyhash, sgx_pubkey_hash,
+ sizeof(sgx_pubkey_hash));
+}
+
+/*
+ * ECREATE must be intercepted to enforce MISCSELECT, ATTRIBUTES and XFRM
+ * restrictions if the guest's allowed-1 settings diverge from hardware.
+ */
+static bool sgx_intercept_encls_ecreate(struct kvm_vcpu *vcpu)
+{
+ struct kvm_cpuid_entry2 *guest_cpuid;
+ u32 eax, ebx, ecx, edx;
+
+ if (!vcpu->kvm->arch.sgx_provisioning_allowed)
+ return true;
+
+ guest_cpuid = kvm_find_cpuid_entry(vcpu, 0x12, 0);
+ if (!guest_cpuid)
+ return true;
+
+ cpuid_count(0x12, 0, &eax, &ebx, &ecx, &edx);
+ if (guest_cpuid->ebx != ebx || guest_cpuid->edx != edx)
+ return true;
+
+ guest_cpuid = kvm_find_cpuid_entry(vcpu, 0x12, 1);
+ if (!guest_cpuid)
+ return true;
+
+ cpuid_count(0x12, 1, &eax, &ebx, &ecx, &edx);
+ if (guest_cpuid->eax != eax || guest_cpuid->ebx != ebx ||
+ guest_cpuid->ecx != ecx || guest_cpuid->edx != edx)
+ return true;
+
+ return false;
+}
+
+void vmx_write_encls_bitmap(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
+{
+ /*
+ * There is no software enable bit for SGX that is virtualized by
+ * hardware, e.g. there's no CR4.SGXE, so when SGX is disabled in the
+ * guest (either by the host or by the guest's BIOS) but enabled in the
+ * host, trap all ENCLS leafs and inject #UD/#GP as needed to emulate
+ * the expected system behavior for ENCLS.
+ */
+ u64 bitmap = -1ull;
+
+ /* Nothing to do if hardware doesn't support SGX */
+ if (!cpu_has_vmx_encls_vmexit())
+ return;
+
+ if (guest_cpuid_has(vcpu, X86_FEATURE_SGX) &&
+ sgx_enabled_in_guest_bios(vcpu)) {
+ if (guest_cpuid_has(vcpu, X86_FEATURE_SGX1)) {
+ bitmap &= ~GENMASK_ULL(ETRACK, ECREATE);
+ if (sgx_intercept_encls_ecreate(vcpu))
+ bitmap |= (1 << ECREATE);
+ }
+
+ if (guest_cpuid_has(vcpu, X86_FEATURE_SGX2))
+ bitmap &= ~GENMASK_ULL(EMODT, EAUG);
+
+ /*
+ * Trap and execute EINIT if launch control is enabled in the
+ * host using the guest's values for launch control MSRs, even
+ * if the guest's values are fixed to hardware default values.
+ * The MSRs are not loaded/saved on VM-Enter/VM-Exit as writing
+ * the MSRs is extraordinarily expensive.
+ */
+ if (boot_cpu_has(X86_FEATURE_SGX_LC))
+ bitmap |= (1 << EINIT);
+
+ if (!vmcs12 && is_guest_mode(vcpu))
+ vmcs12 = get_vmcs12(vcpu);
+ if (vmcs12 && nested_cpu_has_encls_exit(vmcs12))
+ bitmap |= vmcs12->encls_exiting_bitmap;
+ }
+ vmcs_write64(ENCLS_EXITING_BITMAP, bitmap);
+}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.