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Diffstat (limited to 'arch/x86/mm/dump_pagetables.c')
-rw-r--r--arch/x86/mm/dump_pagetables.c98
1 files changed, 78 insertions, 20 deletions
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index f0cedf3395af..a035c2aa7801 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -32,6 +32,8 @@ struct pg_state {
const struct addr_marker *marker;
unsigned long lines;
bool to_dmesg;
+ bool check_wx;
+ unsigned long wx_pages;
};
struct addr_marker {
@@ -155,7 +157,7 @@ static void printk_prot(struct seq_file *m, pgprot_t prot, int level, bool dmsg)
pt_dump_cont_printf(m, dmsg, " ");
if ((level == 4 && pr & _PAGE_PAT) ||
((level == 3 || level == 2) && pr & _PAGE_PAT_LARGE))
- pt_dump_cont_printf(m, dmsg, "pat ");
+ pt_dump_cont_printf(m, dmsg, "PAT ");
else
pt_dump_cont_printf(m, dmsg, " ");
if (pr & _PAGE_GLOBAL)
@@ -198,8 +200,8 @@ static void note_page(struct seq_file *m, struct pg_state *st,
* we have now. "break" is either changing perms, levels or
* address space marker.
*/
- prot = pgprot_val(new_prot) & PTE_FLAGS_MASK;
- cur = pgprot_val(st->current_prot) & PTE_FLAGS_MASK;
+ prot = pgprot_val(new_prot);
+ cur = pgprot_val(st->current_prot);
if (!st->level) {
/* First entry */
@@ -214,6 +216,16 @@ static void note_page(struct seq_file *m, struct pg_state *st,
const char *unit = units;
unsigned long delta;
int width = sizeof(unsigned long) * 2;
+ pgprotval_t pr = pgprot_val(st->current_prot);
+
+ if (st->check_wx && (pr & _PAGE_RW) && !(pr & _PAGE_NX)) {
+ WARN_ONCE(1,
+ "x86/mm: Found insecure W+X mapping at address %p/%pS\n",
+ (void *)st->start_address,
+ (void *)st->start_address);
+ st->wx_pages += (st->current_address -
+ st->start_address) / PAGE_SIZE;
+ }
/*
* Now print the actual finished series
@@ -269,13 +281,13 @@ static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr,
{
int i;
pte_t *start;
+ pgprotval_t prot;
start = (pte_t *) pmd_page_vaddr(addr);
for (i = 0; i < PTRS_PER_PTE; i++) {
- pgprot_t prot = pte_pgprot(*start);
-
+ prot = pte_flags(*start);
st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT);
- note_page(m, st, prot, 4);
+ note_page(m, st, __pgprot(prot), 4);
start++;
}
}
@@ -287,18 +299,19 @@ static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr,
{
int i;
pmd_t *start;
+ pgprotval_t prot;
start = (pmd_t *) pud_page_vaddr(addr);
for (i = 0; i < PTRS_PER_PMD; i++) {
st->current_address = normalize_addr(P + i * PMD_LEVEL_MULT);
if (!pmd_none(*start)) {
- pgprotval_t prot = pmd_val(*start) & PTE_FLAGS_MASK;
-
- if (pmd_large(*start) || !pmd_present(*start))
+ if (pmd_large(*start) || !pmd_present(*start)) {
+ prot = pmd_flags(*start);
note_page(m, st, __pgprot(prot), 3);
- else
+ } else {
walk_pte_level(m, st, *start,
P + i * PMD_LEVEL_MULT);
+ }
} else
note_page(m, st, __pgprot(0), 3);
start++;
@@ -318,19 +331,20 @@ static void walk_pud_level(struct seq_file *m, struct pg_state *st, pgd_t addr,
{
int i;
pud_t *start;
+ pgprotval_t prot;
start = (pud_t *) pgd_page_vaddr(addr);
for (i = 0; i < PTRS_PER_PUD; i++) {
st->current_address = normalize_addr(P + i * PUD_LEVEL_MULT);
if (!pud_none(*start)) {
- pgprotval_t prot = pud_val(*start) & PTE_FLAGS_MASK;
-
- if (pud_large(*start) || !pud_present(*start))
+ if (pud_large(*start) || !pud_present(*start)) {
+ prot = pud_flags(*start);
note_page(m, st, __pgprot(prot), 2);
- else
+ } else {
walk_pmd_level(m, st, *start,
P + i * PUD_LEVEL_MULT);
+ }
} else
note_page(m, st, __pgprot(0), 2);
@@ -344,13 +358,30 @@ static void walk_pud_level(struct seq_file *m, struct pg_state *st, pgd_t addr,
#define pgd_none(a) pud_none(__pud(pgd_val(a)))
#endif
-void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd)
+#ifdef CONFIG_X86_64
+static inline bool is_hypervisor_range(int idx)
+{
+ /*
+ * ffff800000000000 - ffff87ffffffffff is reserved for
+ * the hypervisor.
+ */
+ return paravirt_enabled() &&
+ (idx >= pgd_index(__PAGE_OFFSET) - 16) &&
+ (idx < pgd_index(__PAGE_OFFSET));
+}
+#else
+static inline bool is_hypervisor_range(int idx) { return false; }
+#endif
+
+static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
+ bool checkwx)
{
#ifdef CONFIG_X86_64
pgd_t *start = (pgd_t *) &init_level4_pgt;
#else
pgd_t *start = swapper_pg_dir;
#endif
+ pgprotval_t prot;
int i;
struct pg_state st = {};
@@ -359,16 +390,20 @@ void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd)
st.to_dmesg = true;
}
+ st.check_wx = checkwx;
+ if (checkwx)
+ st.wx_pages = 0;
+
for (i = 0; i < PTRS_PER_PGD; i++) {
st.current_address = normalize_addr(i * PGD_LEVEL_MULT);
- if (!pgd_none(*start)) {
- pgprotval_t prot = pgd_val(*start) & PTE_FLAGS_MASK;
-
- if (pgd_large(*start) || !pgd_present(*start))
+ if (!pgd_none(*start) && !is_hypervisor_range(i)) {
+ if (pgd_large(*start) || !pgd_present(*start)) {
+ prot = pgd_flags(*start);
note_page(m, &st, __pgprot(prot), 1);
- else
+ } else {
walk_pud_level(m, &st, *start,
i * PGD_LEVEL_MULT);
+ }
} else
note_page(m, &st, __pgprot(0), 1);
@@ -378,8 +413,26 @@ void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd)
/* Flush out the last page */
st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT);
note_page(m, &st, __pgprot(0), 0);
+ if (!checkwx)
+ return;
+ if (st.wx_pages)
+ pr_info("x86/mm: Checked W+X mappings: FAILED, %lu W+X pages found.\n",
+ st.wx_pages);
+ else
+ pr_info("x86/mm: Checked W+X mappings: passed, no W+X pages found.\n");
+}
+
+void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd)
+{
+ ptdump_walk_pgd_level_core(m, pgd, false);
+}
+
+void ptdump_walk_pgd_level_checkwx(void)
+{
+ ptdump_walk_pgd_level_core(NULL, NULL, true);
}
+#ifdef CONFIG_X86_PTDUMP
static int ptdump_show(struct seq_file *m, void *v)
{
ptdump_walk_pgd_level(m, NULL);
@@ -397,10 +450,13 @@ static const struct file_operations ptdump_fops = {
.llseek = seq_lseek,
.release = single_release,
};
+#endif
static int pt_dump_init(void)
{
+#ifdef CONFIG_X86_PTDUMP
struct dentry *pe;
+#endif
#ifdef CONFIG_X86_32
/* Not a compile-time constant on x86-32 */
@@ -412,10 +468,12 @@ static int pt_dump_init(void)
address_markers[FIXADDR_START_NR].start_address = FIXADDR_START;
#endif
+#ifdef CONFIG_X86_PTDUMP
pe = debugfs_create_file("kernel_page_tables", 0600, NULL, NULL,
&ptdump_fops);
if (!pe)
return -ENOMEM;
+#endif
return 0;
}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.