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