xref: /kernel/linux/linux-5.10/mm/kasan/init.c (revision 8c2ecf20) 
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 */
34unsigned char kasan_early_shadow_page[PAGE_SIZE] __page_aligned_bss;
35
36#if CONFIG_PGTABLE_LEVELS > 4
37p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D] __page_aligned_bss;
38static 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
43static inline bool kasan_p4d_table(pgd_t pgd)
44{
45	return false;
46}
47#endif
48#if CONFIG_PGTABLE_LEVELS > 3
49pud_t kasan_early_shadow_pud[PTRS_PER_PUD] __page_aligned_bss;
50static 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
55static inline bool kasan_pud_table(p4d_t p4d)
56{
57	return false;
58}
59#endif
60#if CONFIG_PGTABLE_LEVELS > 2
61pmd_t kasan_early_shadow_pmd[PTRS_PER_PMD] __page_aligned_bss;
62static 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
67static inline bool kasan_pmd_table(pud_t pud)
68{
69	return false;
70}
71#endif
72pte_t kasan_early_shadow_pte[PTRS_PER_PTE] __page_aligned_bss;
73
74static 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
79static 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
84static __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
96static 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
113static 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
146static 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#ifdef CONFIG_LOONGARCH
175				pmd_init((unsigned long)p, (unsigned long)invalid_pte_table);
176#endif
177				pud_populate(&init_mm, pud, p);
178			}
179		}
180		zero_pmd_populate(pud, addr, next);
181	} while (pud++, addr = next, addr != end);
182
183	return 0;
184}
185
186static int __ref zero_p4d_populate(pgd_t *pgd, unsigned long addr,
187				unsigned long end)
188{
189	p4d_t *p4d = p4d_offset(pgd, addr);
190	unsigned long next;
191
192	do {
193		next = p4d_addr_end(addr, end);
194		if (IS_ALIGNED(addr, P4D_SIZE) && end - addr >= P4D_SIZE) {
195			pud_t *pud;
196			pmd_t *pmd;
197
198			p4d_populate(&init_mm, p4d,
199					lm_alias(kasan_early_shadow_pud));
200			pud = pud_offset(p4d, addr);
201			pud_populate(&init_mm, pud,
202					lm_alias(kasan_early_shadow_pmd));
203			pmd = pmd_offset(pud, addr);
204			pmd_populate_kernel(&init_mm, pmd,
205					lm_alias(kasan_early_shadow_pte));
206			continue;
207		}
208
209		if (p4d_none(*p4d)) {
210			pud_t *p;
211
212			if (slab_is_available()) {
213				p = pud_alloc(&init_mm, p4d, addr);
214				if (!p)
215					return -ENOMEM;
216			} else {
217				p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
218#ifdef CONFIG_LOONGARCH
219				pud_init((unsigned long)p, (unsigned long)invalid_pmd_table);
220#endif
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 */
236int __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
292static 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(*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
307static 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
322static 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
337static 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
352static void kasan_remove_pte_table(pte_t *pte, unsigned long addr,
353				unsigned long end)
354{
355	unsigned long next;
356
357	for (; addr < end; addr = next, pte++) {
358		next = (addr + PAGE_SIZE) & PAGE_MASK;
359		if (next > end)
360			next = end;
361
362		if (!pte_present(*pte))
363			continue;
364
365		if (WARN_ON(!kasan_early_shadow_page_entry(*pte)))
366			continue;
367		pte_clear(&init_mm, addr, pte);
368	}
369}
370
371static void kasan_remove_pmd_table(pmd_t *pmd, unsigned long addr,
372				unsigned long end)
373{
374	unsigned long next;
375
376	for (; addr < end; addr = next, pmd++) {
377		pte_t *pte;
378
379		next = pmd_addr_end(addr, end);
380
381		if (!pmd_present(*pmd))
382			continue;
383
384		if (kasan_pte_table(*pmd)) {
385			if (IS_ALIGNED(addr, PMD_SIZE) &&
386			    IS_ALIGNED(next, PMD_SIZE)) {
387				pmd_clear(pmd);
388				continue;
389			}
390		}
391		pte = pte_offset_kernel(pmd, addr);
392		kasan_remove_pte_table(pte, addr, next);
393		kasan_free_pte(pte_offset_kernel(pmd, 0), pmd);
394	}
395}
396
397static void kasan_remove_pud_table(pud_t *pud, unsigned long addr,
398				unsigned long end)
399{
400	unsigned long next;
401
402	for (; addr < end; addr = next, pud++) {
403		pmd_t *pmd, *pmd_base;
404
405		next = pud_addr_end(addr, end);
406
407		if (!pud_present(*pud))
408			continue;
409
410		if (kasan_pmd_table(*pud)) {
411			if (IS_ALIGNED(addr, PUD_SIZE) &&
412			    IS_ALIGNED(next, PUD_SIZE)) {
413				pud_clear(pud);
414				continue;
415			}
416		}
417		pmd = pmd_offset(pud, addr);
418		pmd_base = pmd_offset(pud, 0);
419		kasan_remove_pmd_table(pmd, addr, next);
420		kasan_free_pmd(pmd_base, pud);
421	}
422}
423
424static void kasan_remove_p4d_table(p4d_t *p4d, unsigned long addr,
425				unsigned long end)
426{
427	unsigned long next;
428
429	for (; addr < end; addr = next, p4d++) {
430		pud_t *pud;
431
432		next = p4d_addr_end(addr, end);
433
434		if (!p4d_present(*p4d))
435			continue;
436
437		if (kasan_pud_table(*p4d)) {
438			if (IS_ALIGNED(addr, P4D_SIZE) &&
439			    IS_ALIGNED(next, P4D_SIZE)) {
440				p4d_clear(p4d);
441				continue;
442			}
443		}
444		pud = pud_offset(p4d, addr);
445		kasan_remove_pud_table(pud, addr, next);
446		kasan_free_pud(pud_offset(p4d, 0), p4d);
447	}
448}
449
450void kasan_remove_zero_shadow(void *start, unsigned long size)
451{
452	unsigned long addr, end, next;
453	pgd_t *pgd;
454
455	addr = (unsigned long)kasan_mem_to_shadow(start);
456	end = addr + (size >> KASAN_SHADOW_SCALE_SHIFT);
457
458	if (WARN_ON((unsigned long)start %
459			(KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) ||
460	    WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)))
461		return;
462
463	for (; addr < end; addr = next) {
464		p4d_t *p4d;
465
466		next = pgd_addr_end(addr, end);
467
468		pgd = pgd_offset_k(addr);
469		if (!pgd_present(*pgd))
470			continue;
471
472		if (kasan_p4d_table(*pgd)) {
473			if (IS_ALIGNED(addr, PGDIR_SIZE) &&
474			    IS_ALIGNED(next, PGDIR_SIZE)) {
475				pgd_clear(pgd);
476				continue;
477			}
478		}
479
480		p4d = p4d_offset(pgd, addr);
481		kasan_remove_p4d_table(p4d, addr, next);
482		kasan_free_p4d(p4d_offset(pgd, 0), pgd);
483	}
484}
485
486int kasan_add_zero_shadow(void *start, unsigned long size)
487{
488	int ret;
489	void *shadow_start, *shadow_end;
490
491	shadow_start = kasan_mem_to_shadow(start);
492	shadow_end = shadow_start + (size >> KASAN_SHADOW_SCALE_SHIFT);
493
494	if (WARN_ON((unsigned long)start %
495			(KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) ||
496	    WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)))
497		return -EINVAL;
498
499	ret = kasan_populate_early_shadow(shadow_start, shadow_end);
500	if (ret)
501		kasan_remove_zero_shadow(start, size);
502	return ret;
503}
504