linux/arch/x86/kvm/mmu_audit.c

304 lines
6.6 KiB
C

/*
* 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>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
*/
#include <linux/ratelimit.h>
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);