/* * mmu_audit.c: * * Audit code for KVM MMU * * Copyright (C) 2006 Qumranet, Inc. * Copyright 2010 Red Hat, Inc. and/or its affiliates. * * Authors: * Yaniv Kamay * Avi Kivity * Marcelo Tosatti * Xiao Guangrong * * This work is licensed under the terms of the GNU GPL, version 2. See * the COPYING file in the top-level directory. * */ #include char const *audit_point_name[] = { "pre page fault", "post page fault", "pre pte write", "post pte write", "pre sync", "post sync" }; #define audit_printk(kvm, fmt, args...) \ printk(KERN_ERR "audit: (%s) error: " \ fmt, audit_point_name[kvm->arch.audit_point], ##args) typedef void (*inspect_spte_fn) (struct kvm_vcpu *vcpu, u64 *sptep, int level); static void __mmu_spte_walk(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, inspect_spte_fn fn, int level) { int i; for (i = 0; i < PT64_ENT_PER_PAGE; ++i) { u64 *ent = sp->spt; fn(vcpu, ent + i, level); if (is_shadow_present_pte(ent[i]) && !is_last_spte(ent[i], level)) { struct kvm_mmu_page *child; child = page_header(ent[i] & PT64_BASE_ADDR_MASK); __mmu_spte_walk(vcpu, child, fn, level - 1); } } } static void mmu_spte_walk(struct kvm_vcpu *vcpu, inspect_spte_fn fn) { int i; struct kvm_mmu_page *sp; if (!VALID_PAGE(vcpu->arch.mmu.root_hpa)) return; if (vcpu->arch.mmu.root_level == PT64_ROOT_LEVEL) { hpa_t root = vcpu->arch.mmu.root_hpa; sp = page_header(root); __mmu_spte_walk(vcpu, sp, fn, PT64_ROOT_LEVEL); return; } for (i = 0; i < 4; ++i) { hpa_t root = vcpu->arch.mmu.pae_root[i]; if (root && VALID_PAGE(root)) { root &= PT64_BASE_ADDR_MASK; sp = page_header(root); __mmu_spte_walk(vcpu, sp, fn, 2); } } return; } typedef void (*sp_handler) (struct kvm *kvm, struct kvm_mmu_page *sp); static void walk_all_active_sps(struct kvm *kvm, sp_handler fn) { struct kvm_mmu_page *sp; list_for_each_entry(sp, &kvm->arch.active_mmu_pages, link) fn(kvm, sp); } static void audit_mappings(struct kvm_vcpu *vcpu, u64 *sptep, int level) { struct kvm_mmu_page *sp; gfn_t gfn; pfn_t pfn; hpa_t hpa; sp = page_header(__pa(sptep)); if (sp->unsync) { if (level != PT_PAGE_TABLE_LEVEL) { audit_printk(vcpu->kvm, "unsync sp: %p " "level = %d\n", sp, level); return; } } if (!is_shadow_present_pte(*sptep) || !is_last_spte(*sptep, level)) return; gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt); pfn = gfn_to_pfn_atomic(vcpu->kvm, gfn); if (is_error_pfn(pfn)) { kvm_release_pfn_clean(pfn); return; } hpa = pfn << PAGE_SHIFT; if ((*sptep & PT64_BASE_ADDR_MASK) != hpa) audit_printk(vcpu->kvm, "levels %d pfn %llx hpa %llx " "ent %llxn", vcpu->arch.mmu.root_level, pfn, hpa, *sptep); } static void inspect_spte_has_rmap(struct kvm *kvm, u64 *sptep) { static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10); unsigned long *rmapp; struct kvm_mmu_page *rev_sp; gfn_t gfn; rev_sp = page_header(__pa(sptep)); gfn = kvm_mmu_page_get_gfn(rev_sp, sptep - rev_sp->spt); if (!gfn_to_memslot(kvm, gfn)) { if (!__ratelimit(&ratelimit_state)) return; audit_printk(kvm, "no memslot for gfn %llx\n", gfn); audit_printk(kvm, "index %ld of sp (gfn=%llx)\n", (long int)(sptep - rev_sp->spt), rev_sp->gfn); dump_stack(); return; } rmapp = gfn_to_rmap(kvm, gfn, rev_sp->role.level); if (!*rmapp) { if (!__ratelimit(&ratelimit_state)) return; audit_printk(kvm, "no rmap for writable spte %llx\n", *sptep); dump_stack(); } } static void audit_sptes_have_rmaps(struct kvm_vcpu *vcpu, u64 *sptep, int level) { if (is_shadow_present_pte(*sptep) && is_last_spte(*sptep, level)) inspect_spte_has_rmap(vcpu->kvm, sptep); } static void audit_spte_after_sync(struct kvm_vcpu *vcpu, u64 *sptep, int level) { struct kvm_mmu_page *sp = page_header(__pa(sptep)); if (vcpu->kvm->arch.audit_point == AUDIT_POST_SYNC && sp->unsync) audit_printk(vcpu->kvm, "meet unsync sp(%p) after sync " "root.\n", sp); } static void check_mappings_rmap(struct kvm *kvm, struct kvm_mmu_page *sp) { int i; if (sp->role.level != PT_PAGE_TABLE_LEVEL) return; for (i = 0; i < PT64_ENT_PER_PAGE; ++i) { if (!is_rmap_spte(sp->spt[i])) continue; inspect_spte_has_rmap(kvm, sp->spt + i); } } static void audit_write_protection(struct kvm *kvm, struct kvm_mmu_page *sp) { struct kvm_memory_slot *slot; unsigned long *rmapp; u64 *sptep; struct rmap_iterator iter; if (sp->role.direct || sp->unsync || sp->role.invalid) return; slot = gfn_to_memslot(kvm, sp->gfn); rmapp = &slot->rmap[sp->gfn - slot->base_gfn]; for (sptep = rmap_get_first(*rmapp, &iter); sptep; sptep = rmap_get_next(&iter)) { if (is_writable_pte(*sptep)) audit_printk(kvm, "shadow page has writable " "mappings: gfn %llx role %x\n", sp->gfn, sp->role.word); } } static void audit_sp(struct kvm *kvm, struct kvm_mmu_page *sp) { check_mappings_rmap(kvm, sp); audit_write_protection(kvm, sp); } static void audit_all_active_sps(struct kvm *kvm) { walk_all_active_sps(kvm, audit_sp); } static void audit_spte(struct kvm_vcpu *vcpu, u64 *sptep, int level) { audit_sptes_have_rmaps(vcpu, sptep, level); audit_mappings(vcpu, sptep, level); audit_spte_after_sync(vcpu, sptep, level); } static void audit_vcpu_spte(struct kvm_vcpu *vcpu) { mmu_spte_walk(vcpu, audit_spte); } static bool mmu_audit; static struct static_key mmu_audit_key; static void __kvm_mmu_audit(struct kvm_vcpu *vcpu, int point) { static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10); if (!__ratelimit(&ratelimit_state)) return; vcpu->kvm->arch.audit_point = point; audit_all_active_sps(vcpu->kvm); audit_vcpu_spte(vcpu); } static inline void kvm_mmu_audit(struct kvm_vcpu *vcpu, int point) { if (static_key_false((&mmu_audit_key))) __kvm_mmu_audit(vcpu, point); } static void mmu_audit_enable(void) { if (mmu_audit) return; static_key_slow_inc(&mmu_audit_key); mmu_audit = true; } static void mmu_audit_disable(void) { if (!mmu_audit) return; static_key_slow_dec(&mmu_audit_key); mmu_audit = false; } static int mmu_audit_set(const char *val, const struct kernel_param *kp) { int ret; unsigned long enable; ret = strict_strtoul(val, 10, &enable); if (ret < 0) return -EINVAL; switch (enable) { case 0: mmu_audit_disable(); break; case 1: mmu_audit_enable(); break; default: return -EINVAL; } return 0; } static struct kernel_param_ops audit_param_ops = { .set = mmu_audit_set, .get = param_get_bool, }; module_param_cb(mmu_audit, &audit_param_ops, &mmu_audit, 0644);