On Tue, 2021-01-26 at 22:31 +1300, Kai Huang wrote:
> +static int handle_encls_ecreate(struct kvm_vcpu *vcpu)
> +{
> + unsigned long a_hva, m_hva, x_hva, s_hva, secs_hva;
> + struct kvm_cpuid_entry2 *sgx_12_0, *sgx_12_1;
> + gpa_t metadata_gpa, contents_gpa, secs_gpa;
> + struct sgx_pageinfo pageinfo;
> + gva_t pageinfo_gva, secs_gva;
> + u64 attributes, xfrm, size;
> + struct x86_exception ex;
> + u8 max_size_log2;
> + u32 miscselect;
> + int trapnr, r;
> +
> + 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) {
> + kvm_inject_gp(vcpu, 0);
> + return 1;
> + }
> +
> + 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,
> size);
> + return 0;
> + }
> +
> + /*
> + * Verify alignment early. This conveniently avoids having
> to worry
> + * about page splits on userspace addresses.
> + */
> + if (!IS_ALIGNED(pageinfo.metadata, 64) ||
> + !IS_ALIGNED(pageinfo.contents, 4096)) {
> + kvm_inject_gp(vcpu, 0);
> + 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, pageinfo.metadata, false,
> &metadata_gpa) ||
> + sgx_gva_to_gpa(vcpu, pageinfo.contents, false,
> &contents_gpa) ||
> + sgx_gva_to_gpa(vcpu, secs_gva, true, &secs_gpa))
> + return 1;
> +
Do pageinfo.metadata and pageinfo.contents need cannonical checks here?
I was noticing the other day that the guest walker could access host
memory slightly outside of a memslot if it ever got passed a gva with
bits higher that the va bits. Or at least it appeared that way. I
didn't fully wade into the bit math because all callers from the guest
did cannonical checks.
