[thirdparty/linux.git] / mm / ptdump.c

// SPDX-License-Identifier: GPL-2.0

#include <linux/pagewalk.h>
#include <linux/debugfs.h>
#include <linux/ptdump.h>
#include <linux/kasan.h>
#include "internal.h"

#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
/*
 * This is an optimization for KASAN=y case. Since all kasan page tables
 * eventually point to the kasan_early_shadow_page we could call note_page()
 * right away without walking through lower level page tables. This saves
 * us dozens of seconds (minutes for 5-level config) while checking for
 * W+X mapping or reading kernel_page_tables debugfs file.
 */
static inline int note_kasan_page_table(struct mm_walk *walk,
					unsigned long addr)
{
	struct ptdump_state *st = walk->private;

	st->note_page_pte(st, addr, kasan_early_shadow_pte[0]);

	walk->action = ACTION_CONTINUE;

	return 0;
}
#endif

static int ptdump_pgd_entry(pgd_t *pgd, unsigned long addr,
			    unsigned long next, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;
	pgd_t val = READ_ONCE(*pgd);

#if CONFIG_PGTABLE_LEVELS > 4 && \
		(defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
	if (pgd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_p4d)))
		return note_kasan_page_table(walk, addr);
#endif

	if (st->effective_prot_pgd)
		st->effective_prot_pgd(st, val);

	if (pgd_leaf(val)) {
		st->note_page_pgd(st, addr, val);
		walk->action = ACTION_CONTINUE;
	}

	return 0;
}

static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr,
			    unsigned long next, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;
	p4d_t val = READ_ONCE(*p4d);

#if CONFIG_PGTABLE_LEVELS > 3 && \
		(defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
	if (p4d_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pud)))
		return note_kasan_page_table(walk, addr);
#endif

	if (st->effective_prot_p4d)
		st->effective_prot_p4d(st, val);

	if (p4d_leaf(val)) {
		st->note_page_p4d(st, addr, val);
		walk->action = ACTION_CONTINUE;
	}

	return 0;
}

static int ptdump_pud_entry(pud_t *pud, unsigned long addr,
			    unsigned long next, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;
	pud_t val = READ_ONCE(*pud);

#if CONFIG_PGTABLE_LEVELS > 2 && \
		(defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
	if (pud_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pmd)))
		return note_kasan_page_table(walk, addr);
#endif

	if (st->effective_prot_pud)
		st->effective_prot_pud(st, val);

	if (pud_leaf(val)) {
		st->note_page_pud(st, addr, val);
		walk->action = ACTION_CONTINUE;
	}

	return 0;
}

static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr,
			    unsigned long next, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;
	pmd_t val = READ_ONCE(*pmd);

#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
	if (pmd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pte)))
		return note_kasan_page_table(walk, addr);
#endif

	if (st->effective_prot_pmd)
		st->effective_prot_pmd(st, val);
	if (pmd_leaf(val)) {
		st->note_page_pmd(st, addr, val);
		walk->action = ACTION_CONTINUE;
	}

	return 0;
}

static int ptdump_pte_entry(pte_t *pte, unsigned long addr,
			    unsigned long next, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;
	pte_t val = ptep_get_lockless(pte);

	if (st->effective_prot_pte)
		st->effective_prot_pte(st, val);

	st->note_page_pte(st, addr, val);

	return 0;
}

static int ptdump_hole(unsigned long addr, unsigned long next,
		       int depth, struct mm_walk *walk)
{
	struct ptdump_state *st = walk->private;
	pte_t pte_zero = {0};
	pmd_t pmd_zero = {0};
	pud_t pud_zero = {0};
	p4d_t p4d_zero = {0};
	pgd_t pgd_zero = {0};

	switch (depth) {
	case 4:
		st->note_page_pte(st, addr, pte_zero);
		break;
	case 3:
		st->note_page_pmd(st, addr, pmd_zero);
		break;
	case 2:
		st->note_page_pud(st, addr, pud_zero);
		break;
	case 1:
		st->note_page_p4d(st, addr, p4d_zero);
		break;
	case 0:
		st->note_page_pgd(st, addr, pgd_zero);
		break;
	default:
		break;
	}
	return 0;
}

static const struct mm_walk_ops ptdump_ops = {
	.pgd_entry	= ptdump_pgd_entry,
	.p4d_entry	= ptdump_p4d_entry,
	.pud_entry	= ptdump_pud_entry,
	.pmd_entry	= ptdump_pmd_entry,
	.pte_entry	= ptdump_pte_entry,
	.pte_hole	= ptdump_hole,
};

void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd)
{
	const struct ptdump_range *range = st->range;

	get_online_mems();
	mmap_write_lock(mm);
	while (range->start != range->end) {
		walk_page_range_debug(mm, range->start, range->end,
				      &ptdump_ops, pgd, st);
		range++;
	}
	mmap_write_unlock(mm);
	put_online_mems();

	/* Flush out the last page */
	st->note_page_flush(st);
}

static int check_wx_show(struct seq_file *m, void *v)
{
	if (ptdump_check_wx())
		seq_puts(m, "SUCCESS\n");
	else
		seq_puts(m, "FAILED\n");

	return 0;
}

DEFINE_SHOW_ATTRIBUTE(check_wx);

static int ptdump_debugfs_init(void)
{
	debugfs_create_file("check_wx_pages", 0400, NULL, NULL, &check_wx_fops);

	return 0;
}

device_initcall(ptdump_debugfs_init);
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0
	2
	3	#include <linux/pagewalk.h>
	4	#include <linux/debugfs.h>
	5	#include <linux/ptdump.h>
	6	#include <linux/kasan.h>
	7	#include "internal.h"
	8
	9	#if defined(CONFIG_KASAN_GENERIC) \|\| defined(CONFIG_KASAN_SW_TAGS)
	10	/*
	11	* This is an optimization for KASAN=y case. Since all kasan page tables
	12	* eventually point to the kasan_early_shadow_page we could call note_page()
	13	* right away without walking through lower level page tables. This saves
	14	* us dozens of seconds (minutes for 5-level config) while checking for
	15	* W+X mapping or reading kernel_page_tables debugfs file.
	16	*/
	17	static inline int note_kasan_page_table(struct mm_walk *walk,
	18	unsigned long addr)
	19	{
	20	struct ptdump_state *st = walk->private;
	21
	22	st->note_page_pte(st, addr, kasan_early_shadow_pte[0]);
	23
	24	walk->action = ACTION_CONTINUE;
	25
	26	return 0;
	27	}
	28	#endif
	29
	30	static int ptdump_pgd_entry(pgd_t *pgd, unsigned long addr,
	31	unsigned long next, struct mm_walk *walk)
	32	{
	33	struct ptdump_state *st = walk->private;
	34	pgd_t val = READ_ONCE(*pgd);
	35
	36	#if CONFIG_PGTABLE_LEVELS > 4 && \
	37	(defined(CONFIG_KASAN_GENERIC) \|\| defined(CONFIG_KASAN_SW_TAGS))
	38	if (pgd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_p4d)))
	39	return note_kasan_page_table(walk, addr);
	40	#endif
	41
	42	if (st->effective_prot_pgd)
	43	st->effective_prot_pgd(st, val);
	44
	45	if (pgd_leaf(val)) {
	46	st->note_page_pgd(st, addr, val);
	47	walk->action = ACTION_CONTINUE;
	48	}
	49
	50	return 0;
	51	}
	52
	53	static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr,
	54	unsigned long next, struct mm_walk *walk)
	55	{
	56	struct ptdump_state *st = walk->private;
	57	p4d_t val = READ_ONCE(*p4d);
	58
	59	#if CONFIG_PGTABLE_LEVELS > 3 && \
	60	(defined(CONFIG_KASAN_GENERIC) \|\| defined(CONFIG_KASAN_SW_TAGS))
	61	if (p4d_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pud)))
	62	return note_kasan_page_table(walk, addr);
	63	#endif
	64
	65	if (st->effective_prot_p4d)
	66	st->effective_prot_p4d(st, val);
	67
	68	if (p4d_leaf(val)) {
	69	st->note_page_p4d(st, addr, val);
	70	walk->action = ACTION_CONTINUE;
	71	}
	72
	73	return 0;
	74	}
	75
	76	static int ptdump_pud_entry(pud_t *pud, unsigned long addr,
	77	unsigned long next, struct mm_walk *walk)
	78	{
	79	struct ptdump_state *st = walk->private;
	80	pud_t val = READ_ONCE(*pud);
	81
	82	#if CONFIG_PGTABLE_LEVELS > 2 && \
	83	(defined(CONFIG_KASAN_GENERIC) \|\| defined(CONFIG_KASAN_SW_TAGS))
	84	if (pud_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pmd)))
	85	return note_kasan_page_table(walk, addr);
	86	#endif
	87
	88	if (st->effective_prot_pud)
	89	st->effective_prot_pud(st, val);
	90
	91	if (pud_leaf(val)) {
	92	st->note_page_pud(st, addr, val);
	93	walk->action = ACTION_CONTINUE;
	94	}
	95
	96	return 0;
	97	}
	98
	99	static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr,
	100	unsigned long next, struct mm_walk *walk)
	101	{
	102	struct ptdump_state *st = walk->private;
	103	pmd_t val = READ_ONCE(*pmd);
	104
	105	#if defined(CONFIG_KASAN_GENERIC) \|\| defined(CONFIG_KASAN_SW_TAGS)
	106	if (pmd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pte)))
	107	return note_kasan_page_table(walk, addr);
	108	#endif
	109
	110	if (st->effective_prot_pmd)
	111	st->effective_prot_pmd(st, val);
	112	if (pmd_leaf(val)) {
	113	st->note_page_pmd(st, addr, val);
	114	walk->action = ACTION_CONTINUE;
	115	}
	116
	117	return 0;
	118	}
	119
	120	static int ptdump_pte_entry(pte_t *pte, unsigned long addr,
	121	unsigned long next, struct mm_walk *walk)
	122	{
	123	struct ptdump_state *st = walk->private;
	124	pte_t val = ptep_get_lockless(pte);
	125
	126	if (st->effective_prot_pte)
	127	st->effective_prot_pte(st, val);
	128
	129	st->note_page_pte(st, addr, val);
	130
	131	return 0;
	132	}
	133
	134	static int ptdump_hole(unsigned long addr, unsigned long next,
	135	int depth, struct mm_walk *walk)
	136	{
	137	struct ptdump_state *st = walk->private;
	138	pte_t pte_zero = {0};
	139	pmd_t pmd_zero = {0};
	140	pud_t pud_zero = {0};
	141	p4d_t p4d_zero = {0};
	142	pgd_t pgd_zero = {0};
	143
	144	switch (depth) {
	145	case 4:
	146	st->note_page_pte(st, addr, pte_zero);
	147	break;
	148	case 3:
	149	st->note_page_pmd(st, addr, pmd_zero);
	150	break;
	151	case 2:
	152	st->note_page_pud(st, addr, pud_zero);
	153	break;
	154	case 1:
	155	st->note_page_p4d(st, addr, p4d_zero);
	156	break;
	157	case 0:
	158	st->note_page_pgd(st, addr, pgd_zero);
	159	break;
	160	default:
	161	break;
	162	}
	163	return 0;
	164	}
	165
	166	static const struct mm_walk_ops ptdump_ops = {
	167	.pgd_entry = ptdump_pgd_entry,
	168	.p4d_entry = ptdump_p4d_entry,
	169	.pud_entry = ptdump_pud_entry,
	170	.pmd_entry = ptdump_pmd_entry,
	171	.pte_entry = ptdump_pte_entry,
	172	.pte_hole = ptdump_hole,
	173	};
	174
	175	void ptdump_walk_pgd(struct ptdump_state st, struct mm_struct mm, pgd_t *pgd)
	176	{
	177	const struct ptdump_range *range = st->range;
	178
	179	get_online_mems();
	180	mmap_write_lock(mm);
	181	while (range->start != range->end) {
	182	walk_page_range_debug(mm, range->start, range->end,
	183	&ptdump_ops, pgd, st);
	184	range++;
	185	}
	186	mmap_write_unlock(mm);
	187	put_online_mems();
	188
	189	/* Flush out the last page */
	190	st->note_page_flush(st);
	191	}
	192
	193	static int check_wx_show(struct seq_file m, void v)
	194	{
	195	if (ptdump_check_wx())
	196	seq_puts(m, "SUCCESS\n");
	197	else
	198	seq_puts(m, "FAILED\n");
	199
	200	return 0;
	201	}
	202
	203	DEFINE_SHOW_ATTRIBUTE(check_wx);
	204
	205	static int ptdump_debugfs_init(void)
	206	{
	207	debugfs_create_file("check_wx_pages", 0400, NULL, NULL, &check_wx_fops);
	208
	209	return 0;
	210	}
	211
	212	device_initcall(ptdump_debugfs_init);