1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * This file contains some kasan initialization code.
4 *
5 * Copyright (c) 2015 Samsung Electronics Co., Ltd.
6 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 *
12 */
13
14 #include <linux/memblock.h>
15 #include <linux/init.h>
16 #include <linux/kasan.h>
17 #include <linux/kernel.h>
18 #include <linux/mm.h>
19 #include <linux/pfn.h>
20 #include <linux/slab.h>
21
22 #include <asm/page.h>
23 #include <asm/pgalloc.h>
24
25 #include "kasan.h"
26
27 /*
28 * This page serves two purposes:
29 * - It used as early shadow memory. The entire shadow region populated
30 * with this page, before we will be able to setup normal shadow memory.
31 * - Latter it reused it as zero shadow to cover large ranges of memory
32 * that allowed to access, but not handled by kasan (vmalloc/vmemmap ...).
33 */
34 unsigned char kasan_early_shadow_page[PAGE_SIZE] __page_aligned_bss;
35
36 #if CONFIG_PGTABLE_LEVELS > 4
37 p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D] __page_aligned_bss;
kasan_p4d_table(pgd_t pgd)38 static inline bool kasan_p4d_table(pgd_t pgd)
39 {
40 return pgd_page(pgd) == virt_to_page(lm_alias(kasan_early_shadow_p4d));
41 }
42 #else
kasan_p4d_table(pgd_t pgd)43 static inline bool kasan_p4d_table(pgd_t pgd)
44 {
45 return false;
46 }
47 #endif
48 #if CONFIG_PGTABLE_LEVELS > 3
49 pud_t kasan_early_shadow_pud[PTRS_PER_PUD] __page_aligned_bss;
kasan_pud_table(p4d_t p4d)50 static inline bool kasan_pud_table(p4d_t p4d)
51 {
52 return p4d_page(p4d) == virt_to_page(lm_alias(kasan_early_shadow_pud));
53 }
54 #else
kasan_pud_table(p4d_t p4d)55 static inline bool kasan_pud_table(p4d_t p4d)
56 {
57 return false;
58 }
59 #endif
60 #if CONFIG_PGTABLE_LEVELS > 2
61 pmd_t kasan_early_shadow_pmd[PTRS_PER_PMD] __page_aligned_bss;
kasan_pmd_table(pud_t pud)62 static inline bool kasan_pmd_table(pud_t pud)
63 {
64 return pud_page(pud) == virt_to_page(lm_alias(kasan_early_shadow_pmd));
65 }
66 #else
kasan_pmd_table(pud_t pud)67 static inline bool kasan_pmd_table(pud_t pud)
68 {
69 return false;
70 }
71 #endif
72 pte_t kasan_early_shadow_pte[PTRS_PER_PTE] __page_aligned_bss;
73
kasan_pte_table(pmd_t pmd)74 static inline bool kasan_pte_table(pmd_t pmd)
75 {
76 return pmd_page(pmd) == virt_to_page(lm_alias(kasan_early_shadow_pte));
77 }
78
kasan_early_shadow_page_entry(pte_t pte)79 static inline bool kasan_early_shadow_page_entry(pte_t pte)
80 {
81 return pte_page(pte) == virt_to_page(lm_alias(kasan_early_shadow_page));
82 }
83
early_alloc(size_t size,int node)84 static __init void *early_alloc(size_t size, int node)
85 {
86 void *ptr = memblock_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
87 MEMBLOCK_ALLOC_ACCESSIBLE, node);
88
89 if (!ptr)
90 panic("%s: Failed to allocate %zu bytes align=%zx nid=%d from=%llx\n",
91 __func__, size, size, node, (u64)__pa(MAX_DMA_ADDRESS));
92
93 return ptr;
94 }
95
zero_pte_populate(pmd_t * pmd,unsigned long addr,unsigned long end)96 static void __ref zero_pte_populate(pmd_t *pmd, unsigned long addr,
97 unsigned long end)
98 {
99 pte_t *pte = pte_offset_kernel(pmd, addr);
100 pte_t zero_pte;
101
102 zero_pte = pfn_pte(PFN_DOWN(__pa_symbol(kasan_early_shadow_page)),
103 PAGE_KERNEL);
104 zero_pte = pte_wrprotect(zero_pte);
105
106 while (addr + PAGE_SIZE <= end) {
107 set_pte_at(&init_mm, addr, pte, zero_pte);
108 addr += PAGE_SIZE;
109 pte = pte_offset_kernel(pmd, addr);
110 }
111 }
112
zero_pmd_populate(pud_t * pud,unsigned long addr,unsigned long end)113 static int __ref zero_pmd_populate(pud_t *pud, unsigned long addr,
114 unsigned long end)
115 {
116 pmd_t *pmd = pmd_offset(pud, addr);
117 unsigned long next;
118
119 do {
120 next = pmd_addr_end(addr, end);
121
122 if (IS_ALIGNED(addr, PMD_SIZE) && end - addr >= PMD_SIZE) {
123 pmd_populate_kernel(&init_mm, pmd,
124 lm_alias(kasan_early_shadow_pte));
125 continue;
126 }
127
128 if (pmd_none(*pmd)) {
129 pte_t *p;
130
131 if (slab_is_available())
132 p = pte_alloc_one_kernel(&init_mm);
133 else
134 p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
135 if (!p)
136 return -ENOMEM;
137
138 pmd_populate_kernel(&init_mm, pmd, p);
139 }
140 zero_pte_populate(pmd, addr, next);
141 } while (pmd++, addr = next, addr != end);
142
143 return 0;
144 }
145
zero_pud_populate(p4d_t * p4d,unsigned long addr,unsigned long end)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 pud_populate(&init_mm, pud,
174 early_alloc(PAGE_SIZE, NUMA_NO_NODE));
175 }
176 }
177 zero_pmd_populate(pud, addr, next);
178 } while (pud++, addr = next, addr != end);
179
180 return 0;
181 }
182
zero_p4d_populate(pgd_t * pgd,unsigned long addr,unsigned long end)183 static int __ref zero_p4d_populate(pgd_t *pgd, unsigned long addr,
184 unsigned long end)
185 {
186 p4d_t *p4d = p4d_offset(pgd, addr);
187 unsigned long next;
188
189 do {
190 next = p4d_addr_end(addr, end);
191 if (IS_ALIGNED(addr, P4D_SIZE) && end - addr >= P4D_SIZE) {
192 pud_t *pud;
193 pmd_t *pmd;
194
195 p4d_populate(&init_mm, p4d,
196 lm_alias(kasan_early_shadow_pud));
197 pud = pud_offset(p4d, addr);
198 pud_populate(&init_mm, pud,
199 lm_alias(kasan_early_shadow_pmd));
200 pmd = pmd_offset(pud, addr);
201 pmd_populate_kernel(&init_mm, pmd,
202 lm_alias(kasan_early_shadow_pte));
203 continue;
204 }
205
206 if (p4d_none(*p4d)) {
207 pud_t *p;
208
209 if (slab_is_available()) {
210 p = pud_alloc(&init_mm, p4d, addr);
211 if (!p)
212 return -ENOMEM;
213 } else {
214 p4d_populate(&init_mm, p4d,
215 early_alloc(PAGE_SIZE, NUMA_NO_NODE));
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 */
kasan_populate_early_shadow(const void * shadow_start,const void * shadow_end)230 int __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(&init_mm, pgd,
255 lm_alias(kasan_early_shadow_p4d));
256 p4d = p4d_offset(pgd, addr);
257 p4d_populate(&init_mm, 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 p4d_t *p;
270
271 if (slab_is_available()) {
272 p = p4d_alloc(&init_mm, pgd, addr);
273 if (!p)
274 return -ENOMEM;
275 } else {
276 pgd_populate(&init_mm, pgd,
277 early_alloc(PAGE_SIZE, NUMA_NO_NODE));
278 }
279 }
280 zero_p4d_populate(pgd, addr, next);
281 } while (pgd++, addr = next, addr != end);
282
283 return 0;
284 }
285
kasan_free_pte(pte_t * pte_start,pmd_t * pmd)286 static void kasan_free_pte(pte_t *pte_start, pmd_t *pmd)
287 {
288 pte_t *pte;
289 int i;
290
291 for (i = 0; i < PTRS_PER_PTE; i++) {
292 pte = pte_start + i;
293 if (!pte_none(*pte))
294 return;
295 }
296
297 pte_free_kernel(&init_mm, (pte_t *)page_to_virt(pmd_page(*pmd)));
298 pmd_clear(pmd);
299 }
300
kasan_free_pmd(pmd_t * pmd_start,pud_t * pud)301 static void kasan_free_pmd(pmd_t *pmd_start, pud_t *pud)
302 {
303 pmd_t *pmd;
304 int i;
305
306 for (i = 0; i < PTRS_PER_PMD; i++) {
307 pmd = pmd_start + i;
308 if (!pmd_none(*pmd))
309 return;
310 }
311
312 pmd_free(&init_mm, (pmd_t *)page_to_virt(pud_page(*pud)));
313 pud_clear(pud);
314 }
315
kasan_free_pud(pud_t * pud_start,p4d_t * p4d)316 static void kasan_free_pud(pud_t *pud_start, p4d_t *p4d)
317 {
318 pud_t *pud;
319 int i;
320
321 for (i = 0; i < PTRS_PER_PUD; i++) {
322 pud = pud_start + i;
323 if (!pud_none(*pud))
324 return;
325 }
326
327 pud_free(&init_mm, (pud_t *)page_to_virt(p4d_page(*p4d)));
328 p4d_clear(p4d);
329 }
330
kasan_free_p4d(p4d_t * p4d_start,pgd_t * pgd)331 static void kasan_free_p4d(p4d_t *p4d_start, pgd_t *pgd)
332 {
333 p4d_t *p4d;
334 int i;
335
336 for (i = 0; i < PTRS_PER_P4D; i++) {
337 p4d = p4d_start + i;
338 if (!p4d_none(*p4d))
339 return;
340 }
341
342 p4d_free(&init_mm, (p4d_t *)page_to_virt(pgd_page(*pgd)));
343 pgd_clear(pgd);
344 }
345
kasan_remove_pte_table(pte_t * pte,unsigned long addr,unsigned long end)346 static void kasan_remove_pte_table(pte_t *pte, unsigned long addr,
347 unsigned long end)
348 {
349 unsigned long next;
350
351 for (; addr < end; addr = next, pte++) {
352 next = (addr + PAGE_SIZE) & PAGE_MASK;
353 if (next > end)
354 next = end;
355
356 if (!pte_present(*pte))
357 continue;
358
359 if (WARN_ON(!kasan_early_shadow_page_entry(*pte)))
360 continue;
361 pte_clear(&init_mm, addr, pte);
362 }
363 }
364
kasan_remove_pmd_table(pmd_t * pmd,unsigned long addr,unsigned long end)365 static void kasan_remove_pmd_table(pmd_t *pmd, unsigned long addr,
366 unsigned long end)
367 {
368 unsigned long next;
369
370 for (; addr < end; addr = next, pmd++) {
371 pte_t *pte;
372
373 next = pmd_addr_end(addr, end);
374
375 if (!pmd_present(*pmd))
376 continue;
377
378 if (kasan_pte_table(*pmd)) {
379 if (IS_ALIGNED(addr, PMD_SIZE) &&
380 IS_ALIGNED(next, PMD_SIZE)) {
381 pmd_clear(pmd);
382 continue;
383 }
384 }
385 pte = pte_offset_kernel(pmd, addr);
386 kasan_remove_pte_table(pte, addr, next);
387 kasan_free_pte(pte_offset_kernel(pmd, 0), pmd);
388 }
389 }
390
kasan_remove_pud_table(pud_t * pud,unsigned long addr,unsigned long end)391 static void kasan_remove_pud_table(pud_t *pud, unsigned long addr,
392 unsigned long end)
393 {
394 unsigned long next;
395
396 for (; addr < end; addr = next, pud++) {
397 pmd_t *pmd, *pmd_base;
398
399 next = pud_addr_end(addr, end);
400
401 if (!pud_present(*pud))
402 continue;
403
404 if (kasan_pmd_table(*pud)) {
405 if (IS_ALIGNED(addr, PUD_SIZE) &&
406 IS_ALIGNED(next, PUD_SIZE)) {
407 pud_clear(pud);
408 continue;
409 }
410 }
411 pmd = pmd_offset(pud, addr);
412 pmd_base = pmd_offset(pud, 0);
413 kasan_remove_pmd_table(pmd, addr, next);
414 kasan_free_pmd(pmd_base, pud);
415 }
416 }
417
kasan_remove_p4d_table(p4d_t * p4d,unsigned long addr,unsigned long end)418 static void kasan_remove_p4d_table(p4d_t *p4d, unsigned long addr,
419 unsigned long end)
420 {
421 unsigned long next;
422
423 for (; addr < end; addr = next, p4d++) {
424 pud_t *pud;
425
426 next = p4d_addr_end(addr, end);
427
428 if (!p4d_present(*p4d))
429 continue;
430
431 if (kasan_pud_table(*p4d)) {
432 if (IS_ALIGNED(addr, P4D_SIZE) &&
433 IS_ALIGNED(next, P4D_SIZE)) {
434 p4d_clear(p4d);
435 continue;
436 }
437 }
438 pud = pud_offset(p4d, addr);
439 kasan_remove_pud_table(pud, addr, next);
440 kasan_free_pud(pud_offset(p4d, 0), p4d);
441 }
442 }
443
kasan_remove_zero_shadow(void * start,unsigned long size)444 void kasan_remove_zero_shadow(void *start, unsigned long size)
445 {
446 unsigned long addr, end, next;
447 pgd_t *pgd;
448
449 addr = (unsigned long)kasan_mem_to_shadow(start);
450 end = addr + (size >> KASAN_SHADOW_SCALE_SHIFT);
451
452 if (WARN_ON((unsigned long)start %
453 (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) ||
454 WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)))
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
kasan_add_zero_shadow(void * start,unsigned long size)480 int 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 %
489 (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) ||
490 WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)))
491 return -EINVAL;
492
493 ret = kasan_populate_early_shadow(shadow_start, shadow_end);
494 if (ret)
495 kasan_remove_zero_shadow(start, size);
496 return ret;
497 }
498