GNU Linux-libre 4.14.266-gnu1
[releases.git] / arch / x86 / kvm / mmu_audit.c
1 /*
2  * mmu_audit.c:
3  *
4  * Audit code for KVM MMU
5  *
6  * Copyright (C) 2006 Qumranet, Inc.
7  * Copyright 2010 Red Hat, Inc. and/or its affiliates.
8  *
9  * Authors:
10  *   Yaniv Kamay  <yaniv@qumranet.com>
11  *   Avi Kivity   <avi@qumranet.com>
12  *   Marcelo Tosatti <mtosatti@redhat.com>
13  *   Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
14  *
15  * This work is licensed under the terms of the GNU GPL, version 2.  See
16  * the COPYING file in the top-level directory.
17  *
18  */
19
20 #include <linux/ratelimit.h>
21
22 char const *audit_point_name[] = {
23         "pre page fault",
24         "post page fault",
25         "pre pte write",
26         "post pte write",
27         "pre sync",
28         "post sync"
29 };
30
31 #define audit_printk(kvm, fmt, args...)         \
32         printk(KERN_ERR "audit: (%s) error: "   \
33                 fmt, audit_point_name[kvm->arch.audit_point], ##args)
34
35 typedef void (*inspect_spte_fn) (struct kvm_vcpu *vcpu, u64 *sptep, int level);
36
37 static void __mmu_spte_walk(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
38                             inspect_spte_fn fn, int level)
39 {
40         int i;
41
42         for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
43                 u64 *ent = sp->spt;
44
45                 fn(vcpu, ent + i, level);
46
47                 if (is_shadow_present_pte(ent[i]) &&
48                       !is_last_spte(ent[i], level)) {
49                         struct kvm_mmu_page *child;
50
51                         child = page_header(ent[i] & PT64_BASE_ADDR_MASK);
52                         __mmu_spte_walk(vcpu, child, fn, level - 1);
53                 }
54         }
55 }
56
57 static void mmu_spte_walk(struct kvm_vcpu *vcpu, inspect_spte_fn fn)
58 {
59         int i;
60         struct kvm_mmu_page *sp;
61
62         if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
63                 return;
64
65         if (vcpu->arch.mmu.root_level >= PT64_ROOT_4LEVEL) {
66                 hpa_t root = vcpu->arch.mmu.root_hpa;
67
68                 sp = page_header(root);
69                 __mmu_spte_walk(vcpu, sp, fn, vcpu->arch.mmu.root_level);
70                 return;
71         }
72
73         for (i = 0; i < 4; ++i) {
74                 hpa_t root = vcpu->arch.mmu.pae_root[i];
75
76                 if (root && VALID_PAGE(root)) {
77                         root &= PT64_BASE_ADDR_MASK;
78                         sp = page_header(root);
79                         __mmu_spte_walk(vcpu, sp, fn, 2);
80                 }
81         }
82
83         return;
84 }
85
86 typedef void (*sp_handler) (struct kvm *kvm, struct kvm_mmu_page *sp);
87
88 static void walk_all_active_sps(struct kvm *kvm, sp_handler fn)
89 {
90         struct kvm_mmu_page *sp;
91
92         list_for_each_entry(sp, &kvm->arch.active_mmu_pages, link)
93                 fn(kvm, sp);
94 }
95
96 static void audit_mappings(struct kvm_vcpu *vcpu, u64 *sptep, int level)
97 {
98         struct kvm_mmu_page *sp;
99         gfn_t gfn;
100         kvm_pfn_t pfn;
101         hpa_t hpa;
102
103         sp = page_header(__pa(sptep));
104
105         if (sp->unsync) {
106                 if (level != PT_PAGE_TABLE_LEVEL) {
107                         audit_printk(vcpu->kvm, "unsync sp: %p "
108                                      "level = %d\n", sp, level);
109                         return;
110                 }
111         }
112
113         if (!is_shadow_present_pte(*sptep) || !is_last_spte(*sptep, level))
114                 return;
115
116         gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt);
117         pfn = kvm_vcpu_gfn_to_pfn_atomic(vcpu, gfn);
118
119         if (is_error_pfn(pfn))
120                 return;
121
122         hpa =  pfn << PAGE_SHIFT;
123         if ((*sptep & PT64_BASE_ADDR_MASK) != hpa)
124                 audit_printk(vcpu->kvm, "levels %d pfn %llx hpa %llx "
125                              "ent %llxn", vcpu->arch.mmu.root_level, pfn,
126                              hpa, *sptep);
127 }
128
129 static void inspect_spte_has_rmap(struct kvm *kvm, u64 *sptep)
130 {
131         static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
132         struct kvm_rmap_head *rmap_head;
133         struct kvm_mmu_page *rev_sp;
134         struct kvm_memslots *slots;
135         struct kvm_memory_slot *slot;
136         gfn_t gfn;
137
138         rev_sp = page_header(__pa(sptep));
139         gfn = kvm_mmu_page_get_gfn(rev_sp, sptep - rev_sp->spt);
140
141         slots = kvm_memslots_for_spte_role(kvm, rev_sp->role);
142         slot = __gfn_to_memslot(slots, gfn);
143         if (!slot) {
144                 if (!__ratelimit(&ratelimit_state))
145                         return;
146                 audit_printk(kvm, "no memslot for gfn %llx\n", gfn);
147                 audit_printk(kvm, "index %ld of sp (gfn=%llx)\n",
148                        (long int)(sptep - rev_sp->spt), rev_sp->gfn);
149                 dump_stack();
150                 return;
151         }
152
153         rmap_head = __gfn_to_rmap(gfn, rev_sp->role.level, slot);
154         if (!rmap_head->val) {
155                 if (!__ratelimit(&ratelimit_state))
156                         return;
157                 audit_printk(kvm, "no rmap for writable spte %llx\n",
158                              *sptep);
159                 dump_stack();
160         }
161 }
162
163 static void audit_sptes_have_rmaps(struct kvm_vcpu *vcpu, u64 *sptep, int level)
164 {
165         if (is_shadow_present_pte(*sptep) && is_last_spte(*sptep, level))
166                 inspect_spte_has_rmap(vcpu->kvm, sptep);
167 }
168
169 static void audit_spte_after_sync(struct kvm_vcpu *vcpu, u64 *sptep, int level)
170 {
171         struct kvm_mmu_page *sp = page_header(__pa(sptep));
172
173         if (vcpu->kvm->arch.audit_point == AUDIT_POST_SYNC && sp->unsync)
174                 audit_printk(vcpu->kvm, "meet unsync sp(%p) after sync "
175                              "root.\n", sp);
176 }
177
178 static void check_mappings_rmap(struct kvm *kvm, struct kvm_mmu_page *sp)
179 {
180         int i;
181
182         if (sp->role.level != PT_PAGE_TABLE_LEVEL)
183                 return;
184
185         for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
186                 if (!is_shadow_present_pte(sp->spt[i]))
187                         continue;
188
189                 inspect_spte_has_rmap(kvm, sp->spt + i);
190         }
191 }
192
193 static void audit_write_protection(struct kvm *kvm, struct kvm_mmu_page *sp)
194 {
195         struct kvm_rmap_head *rmap_head;
196         u64 *sptep;
197         struct rmap_iterator iter;
198         struct kvm_memslots *slots;
199         struct kvm_memory_slot *slot;
200
201         if (sp->role.direct || sp->unsync || sp->role.invalid)
202                 return;
203
204         slots = kvm_memslots_for_spte_role(kvm, sp->role);
205         slot = __gfn_to_memslot(slots, sp->gfn);
206         rmap_head = __gfn_to_rmap(sp->gfn, PT_PAGE_TABLE_LEVEL, slot);
207
208         for_each_rmap_spte(rmap_head, &iter, sptep) {
209                 if (is_writable_pte(*sptep))
210                         audit_printk(kvm, "shadow page has writable "
211                                      "mappings: gfn %llx role %x\n",
212                                      sp->gfn, sp->role.word);
213         }
214 }
215
216 static void audit_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
217 {
218         check_mappings_rmap(kvm, sp);
219         audit_write_protection(kvm, sp);
220 }
221
222 static void audit_all_active_sps(struct kvm *kvm)
223 {
224         walk_all_active_sps(kvm, audit_sp);
225 }
226
227 static void audit_spte(struct kvm_vcpu *vcpu, u64 *sptep, int level)
228 {
229         audit_sptes_have_rmaps(vcpu, sptep, level);
230         audit_mappings(vcpu, sptep, level);
231         audit_spte_after_sync(vcpu, sptep, level);
232 }
233
234 static void audit_vcpu_spte(struct kvm_vcpu *vcpu)
235 {
236         mmu_spte_walk(vcpu, audit_spte);
237 }
238
239 static bool mmu_audit;
240 static struct static_key mmu_audit_key;
241
242 static void __kvm_mmu_audit(struct kvm_vcpu *vcpu, int point)
243 {
244         static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
245
246         if (!__ratelimit(&ratelimit_state))
247                 return;
248
249         vcpu->kvm->arch.audit_point = point;
250         audit_all_active_sps(vcpu->kvm);
251         audit_vcpu_spte(vcpu);
252 }
253
254 static inline void kvm_mmu_audit(struct kvm_vcpu *vcpu, int point)
255 {
256         if (static_key_false((&mmu_audit_key)))
257                 __kvm_mmu_audit(vcpu, point);
258 }
259
260 static void mmu_audit_enable(void)
261 {
262         if (mmu_audit)
263                 return;
264
265         static_key_slow_inc(&mmu_audit_key);
266         mmu_audit = true;
267 }
268
269 static void mmu_audit_disable(void)
270 {
271         if (!mmu_audit)
272                 return;
273
274         static_key_slow_dec(&mmu_audit_key);
275         mmu_audit = false;
276 }
277
278 static int mmu_audit_set(const char *val, const struct kernel_param *kp)
279 {
280         int ret;
281         unsigned long enable;
282
283         ret = kstrtoul(val, 10, &enable);
284         if (ret < 0)
285                 return -EINVAL;
286
287         switch (enable) {
288         case 0:
289                 mmu_audit_disable();
290                 break;
291         case 1:
292                 mmu_audit_enable();
293                 break;
294         default:
295                 return -EINVAL;
296         }
297
298         return 0;
299 }
300
301 static const struct kernel_param_ops audit_param_ops = {
302         .set = mmu_audit_set,
303         .get = param_get_bool,
304 };
305
306 arch_param_cb(mmu_audit, &audit_param_ops, &mmu_audit, 0644);