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 <ryabinin.a.a@gmail.com>
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
17 #include <asm/page.h>
18 #include <asm/pgalloc.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 */
29 unsigned char kasan_early_shadow_page[PAGE_SIZE] __page_aligned_bss;
30
31 #if CONFIG_PGTABLE_LEVELS > 4
32 p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D] __page_aligned_bss;
33 static 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
38 static inline bool kasan_p4d_table(pgd_t pgd)
39 {
40 return false;
41 }
42 #endif
43 #if CONFIG_PGTABLE_LEVELS > 3
44 pud_t kasan_early_shadow_pud[MAX_PTRS_PER_PUD] __page_aligned_bss;
45 static 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
50 static inline bool kasan_pud_table(p4d_t p4d)
51 {
52 return false;
53 }
54 #endif
55 #if CONFIG_PGTABLE_LEVELS > 2
56 pmd_t kasan_early_shadow_pmd[MAX_PTRS_PER_PMD] __page_aligned_bss;
57 static 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
62 static inline bool kasan_pmd_table(pud_t pud)
63 {
64 return false;
65 }
66 #endif
67 pte_t kasan_early_shadow_pte[MAX_PTRS_PER_PTE + PTE_HWTABLE_PTRS]
68 __page_aligned_bss;
69
70 static 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
75 static 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
80 static __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
92 static 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
109 static 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 if (!p)
132 return -ENOMEM;
133
134 pmd_populate_kernel(&init_mm, pmd, p);
135 }
136 zero_pte_populate(pmd, addr, next);
137 } while (pmd++, addr = next, addr != end);
138
139 return 0;
140 }
141
142 void __weak __meminit pmd_init(void *addr)
143 {
144 }
145
146 static int __ref zero_pud_populate(p4d_t *p4d, unsigned long addr,
147 unsigned long end)
148 {
149 pud_t *pud = pud_offset(p4d, addr);
150 unsigned long next;
151
152 do {
153 next = pud_addr_end(addr, end);
154 if (IS_ALIGNED(addr, PUD_SIZE) && end - addr >= PUD_SIZE) {
155 pmd_t *pmd;
156
157 pud_populate(&init_mm, pud,
158 lm_alias(kasan_early_shadow_pmd));
159 pmd = pmd_offset(pud, addr);
160 pmd_populate_kernel(&init_mm, pmd,
161 lm_alias(kasan_early_shadow_pte));
162 continue;
163 }
164
165 if (pud_none(*pud)) {
166 pmd_t *p;
167
168 if (slab_is_available()) {
169 p = pmd_alloc(&init_mm, pud, addr);
170 if (!p)
171 return -ENOMEM;
172 } else {
173 p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
174 pmd_init(p);
175 pud_populate(&init_mm, pud, p);
176 }
177 }
178 zero_pmd_populate(pud, addr, next);
179 } while (pud++, addr = next, addr != end);
180
181 return 0;
182 }
183
184 void __weak __meminit pud_init(void *addr)
185 {
186 }
187
188 static int __ref zero_p4d_populate(pgd_t *pgd, unsigned long addr,
189 unsigned long end)
190 {
191 p4d_t *p4d = p4d_offset(pgd, addr);
192 unsigned long next;
193
194 do {
195 next = p4d_addr_end(addr, end);
196 if (IS_ALIGNED(addr, P4D_SIZE) && end - addr >= P4D_SIZE) {
197 pud_t *pud;
198 pmd_t *pmd;
199
200 p4d_populate(&init_mm, p4d,
201 lm_alias(kasan_early_shadow_pud));
202 pud = pud_offset(p4d, addr);
203 pud_populate(&init_mm, pud,
204 lm_alias(kasan_early_shadow_pmd));
205 pmd = pmd_offset(pud, addr);
206 pmd_populate_kernel(&init_mm, pmd,
207 lm_alias(kasan_early_shadow_pte));
208 continue;
209 }
210
211 if (p4d_none(*p4d)) {
212 pud_t *p;
213
214 if (slab_is_available()) {
215 p = pud_alloc(&init_mm, p4d, addr);
216 if (!p)
217 return -ENOMEM;
218 } else {
219 p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
220 pud_init(p);
221 p4d_populate(&init_mm, p4d, p);
222 }
223 }
224 zero_pud_populate(p4d, addr, next);
225 } while (p4d++, addr = next, addr != end);
226
227 return 0;
228 }
229
230 /**
231 * kasan_populate_early_shadow - populate shadow memory region with
232 * kasan_early_shadow_page
233 * @shadow_start: start of the memory range to populate
234 * @shadow_end: end of the memory range to populate
235 */
236 int __ref kasan_populate_early_shadow(const void *shadow_start,
237 const void *shadow_end)
238 {
239 unsigned long addr = (unsigned long)shadow_start;
240 unsigned long end = (unsigned long)shadow_end;
241 pgd_t *pgd = pgd_offset_k(addr);
242 unsigned long next;
243
244 do {
245 next = pgd_addr_end(addr, end);
246
247 if (IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) {
248 p4d_t *p4d;
249 pud_t *pud;
250 pmd_t *pmd;
251
252 /*
253 * kasan_early_shadow_pud should be populated with pmds
254 * at this moment.
255 * [pud,pmd]_populate*() below needed only for
256 * 3,2 - level page tables where we don't have
257 * puds,pmds, so pgd_populate(), pud_populate()
258 * is noops.
259 */
260 pgd_populate(&init_mm, pgd,
261 lm_alias(kasan_early_shadow_p4d));
262 p4d = p4d_offset(pgd, addr);
263 p4d_populate(&init_mm, p4d,
264 lm_alias(kasan_early_shadow_pud));
265 pud = pud_offset(p4d, addr);
266 pud_populate(&init_mm, pud,
267 lm_alias(kasan_early_shadow_pmd));
268 pmd = pmd_offset(pud, addr);
269 pmd_populate_kernel(&init_mm, pmd,
270 lm_alias(kasan_early_shadow_pte));
271 continue;
272 }
273
274 if (pgd_none(*pgd)) {
275 p4d_t *p;
276
277 if (slab_is_available()) {
278 p = p4d_alloc(&init_mm, pgd, addr);
279 if (!p)
280 return -ENOMEM;
281 } else {
282 pgd_populate(&init_mm, pgd,
283 early_alloc(PAGE_SIZE, NUMA_NO_NODE));
284 }
285 }
286 zero_p4d_populate(pgd, addr, next);
287 } while (pgd++, addr = next, addr != end);
288
289 return 0;
290 }
291
292 static void kasan_free_pte(pte_t *pte_start, pmd_t *pmd)
293 {
294 pte_t *pte;
295 int i;
296
297 for (i = 0; i < PTRS_PER_PTE; i++) {
298 pte = pte_start + i;
299 if (!pte_none(ptep_get(pte)))
300 return;
301 }
302
303 pte_free_kernel(&init_mm, (pte_t *)page_to_virt(pmd_page(*pmd)));
304 pmd_clear(pmd);
305 }
306
307 static void kasan_free_pmd(pmd_t *pmd_start, pud_t *pud)
308 {
309 pmd_t *pmd;
310 int i;
311
312 for (i = 0; i < PTRS_PER_PMD; i++) {
313 pmd = pmd_start + i;
314 if (!pmd_none(*pmd))
315 return;
316 }
317
318 pmd_free(&init_mm, (pmd_t *)page_to_virt(pud_page(*pud)));
319 pud_clear(pud);
320 }
321
322 static void kasan_free_pud(pud_t *pud_start, p4d_t *p4d)
323 {
324 pud_t *pud;
325 int i;
326
327 for (i = 0; i < PTRS_PER_PUD; i++) {
328 pud = pud_start + i;
329 if (!pud_none(*pud))
330 return;
331 }
332
333 pud_free(&init_mm, (pud_t *)page_to_virt(p4d_page(*p4d)));
334 p4d_clear(p4d);
335 }
336
337 static void kasan_free_p4d(p4d_t *p4d_start, pgd_t *pgd)
338 {
339 p4d_t *p4d;
340 int i;
341
342 for (i = 0; i < PTRS_PER_P4D; i++) {
343 p4d = p4d_start + i;
344 if (!p4d_none(*p4d))
345 return;
346 }
347
348 p4d_free(&init_mm, (p4d_t *)page_to_virt(pgd_page(*pgd)));
349 pgd_clear(pgd);
350 }
351
352 static void kasan_remove_pte_table(pte_t *pte, unsigned long addr,
353 unsigned long end)
354 {
355 unsigned long next;
356 pte_t ptent;
357
358 for (; addr < end; addr = next, pte++) {
359 next = (addr + PAGE_SIZE) & PAGE_MASK;
360 if (next > end)
361 next = end;
362
363 ptent = ptep_get(pte);
364
365 if (!pte_present(ptent))
366 continue;
367
368 if (WARN_ON(!kasan_early_shadow_page_entry(ptent)))
369 continue;
370 pte_clear(&init_mm, addr, pte);
371 }
372 }
373
374 static void kasan_remove_pmd_table(pmd_t *pmd, unsigned long addr,
375 unsigned long end)
376 {
377 unsigned long next;
378
379 for (; addr < end; addr = next, pmd++) {
380 pte_t *pte;
381
382 next = pmd_addr_end(addr, end);
383
384 if (!pmd_present(*pmd))
385 continue;
386
387 if (kasan_pte_table(*pmd)) {
388 if (IS_ALIGNED(addr, PMD_SIZE) &&
389 IS_ALIGNED(next, PMD_SIZE)) {
390 pmd_clear(pmd);
391 continue;
392 }
393 }
394 pte = pte_offset_kernel(pmd, addr);
395 kasan_remove_pte_table(pte, addr, next);
396 kasan_free_pte(pte_offset_kernel(pmd, 0), pmd);
397 }
398 }
399
400 static void kasan_remove_pud_table(pud_t *pud, unsigned long addr,
401 unsigned long end)
402 {
403 unsigned long next;
404
405 for (; addr < end; addr = next, pud++) {
406 pmd_t *pmd, *pmd_base;
407
408 next = pud_addr_end(addr, end);
409
410 if (!pud_present(*pud))
411 continue;
412
413 if (kasan_pmd_table(*pud)) {
414 if (IS_ALIGNED(addr, PUD_SIZE) &&
415 IS_ALIGNED(next, PUD_SIZE)) {
416 pud_clear(pud);
417 continue;
418 }
419 }
420 pmd = pmd_offset(pud, addr);
421 pmd_base = pmd_offset(pud, 0);
422 kasan_remove_pmd_table(pmd, addr, next);
423 kasan_free_pmd(pmd_base, pud);
424 }
425 }
426
427 static void kasan_remove_p4d_table(p4d_t *p4d, unsigned long addr,
428 unsigned long end)
429 {
430 unsigned long next;
431
432 for (; addr < end; addr = next, p4d++) {
433 pud_t *pud;
434
435 next = p4d_addr_end(addr, end);
436
437 if (!p4d_present(*p4d))
438 continue;
439
440 if (kasan_pud_table(*p4d)) {
441 if (IS_ALIGNED(addr, P4D_SIZE) &&
442 IS_ALIGNED(next, P4D_SIZE)) {
443 p4d_clear(p4d);
444 continue;
445 }
446 }
447 pud = pud_offset(p4d, addr);
448 kasan_remove_pud_table(pud, addr, next);
449 kasan_free_pud(pud_offset(p4d, 0), p4d);
450 }
451 }
452
453 void kasan_remove_zero_shadow(void *start, unsigned long size)
454 {
455 unsigned long addr, end, next;
456 pgd_t *pgd;
457
458 addr = (unsigned long)kasan_mem_to_shadow(start);
459 end = addr + (size >> KASAN_SHADOW_SCALE_SHIFT);
460
461 if (WARN_ON((unsigned long)start % KASAN_MEMORY_PER_SHADOW_PAGE) ||
462 WARN_ON(size % KASAN_MEMORY_PER_SHADOW_PAGE))
463 return;
464
465 for (; addr < end; addr = next) {
466 p4d_t *p4d;
467
468 next = pgd_addr_end(addr, end);
469
470 pgd = pgd_offset_k(addr);
471 if (!pgd_present(*pgd))
472 continue;
473
474 if (kasan_p4d_table(*pgd)) {
475 if (IS_ALIGNED(addr, PGDIR_SIZE) &&
476 IS_ALIGNED(next, PGDIR_SIZE)) {
477 pgd_clear(pgd);
478 continue;
479 }
480 }
481
482 p4d = p4d_offset(pgd, addr);
483 kasan_remove_p4d_table(p4d, addr, next);
484 kasan_free_p4d(p4d_offset(pgd, 0), pgd);
485 }
486 }
487
488 int kasan_add_zero_shadow(void *start, unsigned long size)
489 {
490 int ret;
491 void *shadow_start, *shadow_end;
492
493 shadow_start = kasan_mem_to_shadow(start);
494 shadow_end = shadow_start + (size >> KASAN_SHADOW_SCALE_SHIFT);
495
496 if (WARN_ON((unsigned long)start % KASAN_MEMORY_PER_SHADOW_PAGE) ||
497 WARN_ON(size % KASAN_MEMORY_PER_SHADOW_PAGE))
498 return -EINVAL;
499
500 ret = kasan_populate_early_shadow(shadow_start, shadow_end);
501 if (ret)
502 kasan_remove_zero_shadow(start, size);
503 return ret;
504 }
505
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