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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * This file contains KASAN shadow initialization code.
4 *
5 * Copyright (c) 2015 Samsung Electronics Co., Ltd.
6 * Author: Andrey Ryabinin <[email protected]>
7 */
8
9#include <linux/memblock.h>
10#include <linux/init.h>
11#include <linux/kasan.h>
12#include <linux/kernel.h>
13#include <linux/mm.h>
14#include <linux/pfn.h>
15#include <linux/slab.h>
16#include <linux/pgalloc.h>
17
18#include <asm/page.h>
19
20#include "kasan.h"
21
22/*
23 * This page serves two purposes:
24 * - It used as early shadow memory. The entire shadow region populated
25 * with this page, before we will be able to setup normal shadow memory.
26 * - Latter it reused it as zero shadow to cover large ranges of memory
27 * that allowed to access, but not handled by kasan (vmalloc/vmemmap ...).
28 */
29unsigned char kasan_early_shadow_page[PAGE_SIZE] __bss_pgtbl;
30
31#if CONFIG_PGTABLE_LEVELS > 4
32p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D] __bss_pgtbl;
33static inline bool kasan_p4d_table(pgd_t pgd)
34{
35 return pgd_page(pgd) == virt_to_page(lm_alias(kasan_early_shadow_p4d));
36}
37#else
38static inline bool kasan_p4d_table(pgd_t pgd)
39{
40 return false;
41}
42#endif
43#if CONFIG_PGTABLE_LEVELS > 3
44pud_t kasan_early_shadow_pud[MAX_PTRS_PER_PUD] __bss_pgtbl;
45static inline bool kasan_pud_table(p4d_t p4d)
46{
47 return p4d_page(p4d) == virt_to_page(lm_alias(kasan_early_shadow_pud));
48}
49#else
50static inline bool kasan_pud_table(p4d_t p4d)
51{
52 return false;
53}
54#endif
55#if CONFIG_PGTABLE_LEVELS > 2
56pmd_t kasan_early_shadow_pmd[MAX_PTRS_PER_PMD] __bss_pgtbl;
57static inline bool kasan_pmd_table(pud_t pud)
58{
59 return pud_page(pud) == virt_to_page(lm_alias(kasan_early_shadow_pmd));
60}
61#else
62static inline bool kasan_pmd_table(pud_t pud)
63{
64 return false;
65}
66#endif
67pte_t kasan_early_shadow_pte[MAX_PTRS_PER_PTE + PTE_HWTABLE_PTRS]
68 __bss_pgtbl;
69
70static inline bool kasan_pte_table(pmd_t pmd)
71{
72 return pmd_page(pmd) == virt_to_page(lm_alias(kasan_early_shadow_pte));
73}
74
75static inline bool kasan_early_shadow_page_entry(pte_t pte)
76{
77 return pte_page(pte) == virt_to_page(lm_alias(kasan_early_shadow_page));
78}
79
80static __init void *early_alloc(size_t size, int node)
81{
82 void *ptr = memblock_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
83 MEMBLOCK_ALLOC_ACCESSIBLE, node);
84
85 if (!ptr)
86 panic("%s: Failed to allocate %zu bytes align=%zx nid=%d from=%llx\n",
87 __func__, size, size, node, (u64)__pa(MAX_DMA_ADDRESS));
88
89 return ptr;
90}
91
92static void __ref zero_pte_populate(pmd_t *pmd, unsigned long addr,
93 unsigned long end)
94{
95 pte_t *pte = pte_offset_kernel(pmd, addr);
96 pte_t zero_pte;
97
98 zero_pte = pfn_pte(PFN_DOWN(__pa_symbol(kasan_early_shadow_page)),
99 PAGE_KERNEL);
100 zero_pte = pte_wrprotect(zero_pte);
101
102 while (addr + PAGE_SIZE <= end) {
103 set_pte_at(&init_mm, addr, pte, zero_pte);
104 addr += PAGE_SIZE;
105 pte = pte_offset_kernel(pmd, addr);
106 }
107}
108
109static int __ref zero_pmd_populate(pud_t *pud, unsigned long addr,
110 unsigned long end)
111{
112 pmd_t *pmd = pmd_offset(pud, addr);
113 unsigned long next;
114
115 do {
116 next = pmd_addr_end(addr, end);
117
118 if (IS_ALIGNED(addr, PMD_SIZE) && end - addr >= PMD_SIZE) {
119 pmd_populate_kernel(&init_mm, pmd,
120 lm_alias(kasan_early_shadow_pte));
121 continue;
122 }
123
124 if (pmd_none(*pmd)) {
125 pte_t *p;
126
127 if (slab_is_available())
128 p = pte_alloc_one_kernel(&init_mm);
129 else {
130 p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
131 kernel_pte_init(p);
132 }
133 if (!p)
134 return -ENOMEM;
135
136 pmd_populate_kernel(&init_mm, pmd, p);
137 }
138 zero_pte_populate(pmd, addr, next);
139 } while (pmd++, addr = next, addr != end);
140
141 return 0;
142}
143
144static int __ref zero_pud_populate(p4d_t *p4d, unsigned long addr,
145 unsigned long end)
146{
147 pud_t *pud = pud_offset(p4d, addr);
148 unsigned long next;
149
150 do {
151 next = pud_addr_end(addr, end);
152 if (IS_ALIGNED(addr, PUD_SIZE) && end - addr >= PUD_SIZE) {
153 pmd_t *pmd;
154
155 pud_populate(&init_mm, pud,
156 lm_alias(kasan_early_shadow_pmd));
157 pmd = pmd_offset(pud, addr);
158 pmd_populate_kernel(&init_mm, pmd,
159 lm_alias(kasan_early_shadow_pte));
160 continue;
161 }
162
163 if (pud_none(*pud)) {
164 pmd_t *p;
165
166 if (slab_is_available()) {
167 p = pmd_alloc(&init_mm, pud, addr);
168 if (!p)
169 return -ENOMEM;
170 } else {
171 p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
172 pmd_init(p);
173 pud_populate(&init_mm, pud, p);
174 }
175 }
176 zero_pmd_populate(pud, addr, next);
177 } while (pud++, addr = next, addr != end);
178
179 return 0;
180}
181
182static int __ref zero_p4d_populate(pgd_t *pgd, unsigned long addr,
183 unsigned long end)
184{
185 p4d_t *p4d = p4d_offset(pgd, addr);
186 unsigned long next;
187
188 do {
189 next = p4d_addr_end(addr, end);
190 if (IS_ALIGNED(addr, P4D_SIZE) && end - addr >= P4D_SIZE) {
191 pud_t *pud;
192 pmd_t *pmd;
193
194 p4d_populate_kernel(addr, p4d,
195 lm_alias(kasan_early_shadow_pud));
196 pud = pud_offset(p4d, addr);
197 pud_populate(&init_mm, pud,
198 lm_alias(kasan_early_shadow_pmd));
199 pmd = pmd_offset(pud, addr);
200 pmd_populate_kernel(&init_mm, pmd,
201 lm_alias(kasan_early_shadow_pte));
202 continue;
203 }
204
205 if (p4d_none(*p4d)) {
206 pud_t *p;
207
208 if (slab_is_available()) {
209 p = pud_alloc(&init_mm, p4d, addr);
210 if (!p)
211 return -ENOMEM;
212 } else {
213 p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
214 pud_init(p);
215 p4d_populate_kernel(addr, p4d, p);
216 }
217 }
218 zero_pud_populate(p4d, addr, next);
219 } while (p4d++, addr = next, addr != end);
220
221 return 0;
222}
223
224/**
225 * kasan_populate_early_shadow - populate shadow memory region with
226 * kasan_early_shadow_page
227 * @shadow_start: start of the memory range to populate
228 * @shadow_end: end of the memory range to populate
229 */
230int __ref kasan_populate_early_shadow(const void *shadow_start,
231 const void *shadow_end)
232{
233 unsigned long addr = (unsigned long)shadow_start;
234 unsigned long end = (unsigned long)shadow_end;
235 pgd_t *pgd = pgd_offset_k(addr);
236 unsigned long next;
237
238 do {
239 next = pgd_addr_end(addr, end);
240
241 if (IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) {
242 p4d_t *p4d;
243 pud_t *pud;
244 pmd_t *pmd;
245
246 /*
247 * kasan_early_shadow_pud should be populated with pmds
248 * at this moment.
249 * [pud,pmd]_populate*() below needed only for
250 * 3,2 - level page tables where we don't have
251 * puds,pmds, so pgd_populate(), pud_populate()
252 * is noops.
253 */
254 pgd_populate_kernel(addr, pgd,
255 lm_alias(kasan_early_shadow_p4d));
256 p4d = p4d_offset(pgd, addr);
257 p4d_populate_kernel(addr, p4d,
258 lm_alias(kasan_early_shadow_pud));
259 pud = pud_offset(p4d, addr);
260 pud_populate(&init_mm, pud,
261 lm_alias(kasan_early_shadow_pmd));
262 pmd = pmd_offset(pud, addr);
263 pmd_populate_kernel(&init_mm, pmd,
264 lm_alias(kasan_early_shadow_pte));
265 continue;
266 }
267
268 if (pgd_none(*pgd)) {
269
270 if (slab_is_available()) {
271 if (!p4d_alloc(&init_mm, pgd, addr))
272 return -ENOMEM;
273 } else {
274 pgd_populate_kernel(addr, pgd,
275 early_alloc(PAGE_SIZE, NUMA_NO_NODE));
276 }
277 }
278 zero_p4d_populate(pgd, addr, next);
279 } while (pgd++, addr = next, addr != end);
280
281 return 0;
282}
283
284static void kasan_free_pte(pte_t *pte_start, pmd_t *pmd)
285{
286 pte_t *pte;
287 int i;
288
289 for (i = 0; i < PTRS_PER_PTE; i++) {
290 pte = pte_start + i;
291 if (!pte_none(ptep_get(pte)))
292 return;
293 }
294
295 pte_free_kernel(&init_mm, pte_start);
296 pmd_clear(pmd);
297}
298
299static void kasan_free_pmd(pmd_t *pmd_start, pud_t *pud)
300{
301 pmd_t *pmd;
302 int i;
303
304 for (i = 0; i < PTRS_PER_PMD; i++) {
305 pmd = pmd_start + i;
306 if (!pmd_none(*pmd))
307 return;
308 }
309
310 pmd_free(&init_mm, pmd_start);
311 pud_clear(pud);
312}
313
314static void kasan_free_pud(pud_t *pud_start, p4d_t *p4d)
315{
316 pud_t *pud;
317 int i;
318
319 for (i = 0; i < PTRS_PER_PUD; i++) {
320 pud = pud_start + i;
321 if (!pud_none(*pud))
322 return;
323 }
324
325 pud_free(&init_mm, pud_start);
326 p4d_clear(p4d);
327}
328
329static void kasan_free_p4d(p4d_t *p4d_start, pgd_t *pgd)
330{
331 p4d_t *p4d;
332 int i;
333
334 for (i = 0; i < PTRS_PER_P4D; i++) {
335 p4d = p4d_start + i;
336 if (!p4d_none(*p4d))
337 return;
338 }
339
340 p4d_free(&init_mm, p4d_start);
341 pgd_clear(pgd);
342}
343
344static void kasan_remove_pte_table(pte_t *pte, unsigned long addr,
345 unsigned long end)
346{
347 unsigned long next;
348 pte_t ptent;
349
350 for (; addr < end; addr = next, pte++) {
351 next = (addr + PAGE_SIZE) & PAGE_MASK;
352 if (next > end)
353 next = end;
354
355 ptent = ptep_get(pte);
356
357 if (!pte_present(ptent))
358 continue;
359
360 if (WARN_ON(!kasan_early_shadow_page_entry(ptent)))
361 continue;
362 pte_clear(&init_mm, addr, pte);
363 }
364}
365
366static void kasan_remove_pmd_table(pmd_t *pmd, unsigned long addr,
367 unsigned long end)
368{
369 unsigned long next;
370
371 for (; addr < end; addr = next, pmd++) {
372 pte_t *pte;
373
374 next = pmd_addr_end(addr, end);
375
376 if (!pmd_present(*pmd))
377 continue;
378
379 if (kasan_pte_table(*pmd)) {
380 if (IS_ALIGNED(addr, PMD_SIZE) &&
381 IS_ALIGNED(next, PMD_SIZE)) {
382 pmd_clear(pmd);
383 continue;
384 }
385 }
386 pte = pte_offset_kernel(pmd, addr);
387 kasan_remove_pte_table(pte, addr, next);
388 kasan_free_pte(pte_offset_kernel(pmd, 0), pmd);
389 }
390}
391
392static void kasan_remove_pud_table(pud_t *pud, unsigned long addr,
393 unsigned long end)
394{
395 unsigned long next;
396
397 for (; addr < end; addr = next, pud++) {
398 pmd_t *pmd, *pmd_base;
399
400 next = pud_addr_end(addr, end);
401
402 if (!pud_present(*pud))
403 continue;
404
405 if (kasan_pmd_table(*pud)) {
406 if (IS_ALIGNED(addr, PUD_SIZE) &&
407 IS_ALIGNED(next, PUD_SIZE)) {
408 pud_clear(pud);
409 continue;
410 }
411 }
412 pmd = pmd_offset(pud, addr);
413 pmd_base = pmd_offset(pud, 0);
414 kasan_remove_pmd_table(pmd, addr, next);
415 kasan_free_pmd(pmd_base, pud);
416 }
417}
418
419static void kasan_remove_p4d_table(p4d_t *p4d, unsigned long addr,
420 unsigned long end)
421{
422 unsigned long next;
423
424 for (; addr < end; addr = next, p4d++) {
425 pud_t *pud;
426
427 next = p4d_addr_end(addr, end);
428
429 if (!p4d_present(*p4d))
430 continue;
431
432 if (kasan_pud_table(*p4d)) {
433 if (IS_ALIGNED(addr, P4D_SIZE) &&
434 IS_ALIGNED(next, P4D_SIZE)) {
435 p4d_clear(p4d);
436 continue;
437 }
438 }
439 pud = pud_offset(p4d, addr);
440 kasan_remove_pud_table(pud, addr, next);
441 kasan_free_pud(pud_offset(p4d, 0), p4d);
442 }
443}
444
445void kasan_remove_zero_shadow(void *start, unsigned long size)
446{
447 unsigned long addr, end, next;
448 pgd_t *pgd;
449
450 addr = (unsigned long)kasan_mem_to_shadow(start);
451 end = addr + (size >> KASAN_SHADOW_SCALE_SHIFT);
452
453 if (WARN_ON((unsigned long)start % KASAN_MEMORY_PER_SHADOW_PAGE) ||
454 WARN_ON(size % KASAN_MEMORY_PER_SHADOW_PAGE))
455 return;
456
457 for (; addr < end; addr = next) {
458 p4d_t *p4d;
459
460 next = pgd_addr_end(addr, end);
461
462 pgd = pgd_offset_k(addr);
463 if (!pgd_present(*pgd))
464 continue;
465
466 if (kasan_p4d_table(*pgd)) {
467 if (IS_ALIGNED(addr, PGDIR_SIZE) &&
468 IS_ALIGNED(next, PGDIR_SIZE)) {
469 pgd_clear(pgd);
470 continue;
471 }
472 }
473
474 p4d = p4d_offset(pgd, addr);
475 kasan_remove_p4d_table(p4d, addr, next);
476 kasan_free_p4d(p4d_offset(pgd, 0), pgd);
477 }
478}
479
480int kasan_add_zero_shadow(void *start, unsigned long size)
481{
482 int ret;
483 void *shadow_start, *shadow_end;
484
485 shadow_start = kasan_mem_to_shadow(start);
486 shadow_end = shadow_start + (size >> KASAN_SHADOW_SCALE_SHIFT);
487
488 if (WARN_ON((unsigned long)start % KASAN_MEMORY_PER_SHADOW_PAGE) ||
489 WARN_ON(size % KASAN_MEMORY_PER_SHADOW_PAGE))
490 return -EINVAL;
491
492 ret = kasan_populate_early_shadow(shadow_start, shadow_end);
493 if (ret)
494 kasan_remove_zero_shadow(start, size);
495 return ret;
496}