| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * 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 <yaniv@qumranet.com> |
| * Avi Kivity <avi@qumranet.com> |
| * Marcelo Tosatti <mtosatti@redhat.com> |
| * Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> |
| */ |
| |
| #include <linux/ratelimit.h> |
| |
| static 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 = to_shadow_page(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_4LEVEL) { |
| hpa_t root = vcpu->arch.mmu->root_hpa; |
| |
| sp = to_shadow_page(root); |
| __mmu_spte_walk(vcpu, sp, fn, vcpu->arch.mmu->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 = to_shadow_page(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; |
| kvm_pfn_t pfn; |
| hpa_t hpa; |
| |
| sp = sptep_to_sp(sptep); |
| |
| if (sp->unsync) { |
| if (level != PG_LEVEL_4K) { |
| 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 = kvm_vcpu_gfn_to_pfn_atomic(vcpu, gfn); |
| |
| if (is_error_pfn(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); |
| struct kvm_rmap_head *rmap_head; |
| struct kvm_mmu_page *rev_sp; |
| struct kvm_memslots *slots; |
| struct kvm_memory_slot *slot; |
| gfn_t gfn; |
| |
| rev_sp = sptep_to_sp(sptep); |
| gfn = kvm_mmu_page_get_gfn(rev_sp, sptep - rev_sp->spt); |
| |
| slots = kvm_memslots_for_spte_role(kvm, rev_sp->role); |
| slot = __gfn_to_memslot(slots, gfn); |
| if (!slot) { |
| 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; |
| } |
| |
| rmap_head = __gfn_to_rmap(gfn, rev_sp->role.level, slot); |
| if (!rmap_head->val) { |
| 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 = sptep_to_sp(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 != PG_LEVEL_4K) |
| return; |
| |
| for (i = 0; i < PT64_ENT_PER_PAGE; ++i) { |
| if (!is_shadow_present_pte(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_rmap_head *rmap_head; |
| u64 *sptep; |
| struct rmap_iterator iter; |
| struct kvm_memslots *slots; |
| struct kvm_memory_slot *slot; |
| |
| if (sp->role.direct || sp->unsync || sp->role.invalid) |
| return; |
| |
| slots = kvm_memslots_for_spte_role(kvm, sp->role); |
| slot = __gfn_to_memslot(slots, sp->gfn); |
| rmap_head = __gfn_to_rmap(sp->gfn, PG_LEVEL_4K, slot); |
| |
| for_each_rmap_spte(rmap_head, &iter, sptep) { |
| 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 = kstrtoul(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 const struct kernel_param_ops audit_param_ops = { |
| .set = mmu_audit_set, |
| .get = param_get_bool, |
| }; |
| |
| arch_param_cb(mmu_audit, &audit_param_ops, &mmu_audit, 0644); |