diff options
Diffstat (limited to 'kernel/arch/x86/kvm/mmu_audit.c')
| -rw-r--r-- | kernel/arch/x86/kvm/mmu_audit.c | 299 |
1 files changed, 299 insertions, 0 deletions
diff --git a/kernel/arch/x86/kvm/mmu_audit.c b/kernel/arch/x86/kvm/mmu_audit.c new file mode 100644 index 000000000..9ade5cfb5 --- /dev/null +++ b/kernel/arch/x86/kvm/mmu_audit.c @@ -0,0 +1,299 @@ +/* + * 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)) + 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) +{ + unsigned long *rmapp; + u64 *sptep; + struct rmap_iterator iter; + + if (sp->role.direct || sp->unsync || sp->role.invalid) + return; + + rmapp = gfn_to_rmap(kvm, sp->gfn, PT_PAGE_TABLE_LEVEL); + + 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 = 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 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); |