Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit d878efce authored by Joerg Roedel's avatar Joerg Roedel Committed by Thomas Gleixner
Browse files

x86/mm/pti: Move user W+X check into pti_finalize() 



The user page-table gets the updated kernel mappings in pti_finalize(),
which runs after the RO+X permissions got applied to the kernel page-table
in mark_readonly().

But with CONFIG_DEBUG_WX enabled, the user page-table is already checked in
mark_readonly() for insecure mappings.  This causes false-positive
warnings, because the user page-table did not get the updated mappings yet.

Move the W+X check for the user page-table into pti_finalize() after it
updated all required mappings.

[ tglx: Folded !NX supported fix ]

Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Waiman Long <llong@redhat.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca>
Cc: joro@8bytes.org
Link: https://lkml.kernel.org/r/1533727000-9172-1-git-send-email-joro@8bytes.org
parent a29dba16

arch/x86/include/asm/pgtable.h

+5 −2
Original line number Diff line number Diff line
@@ -30,11 +30,14 @@ int __init __early_make_pgtable(unsigned long address, pmdval_t pmd); 
void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd);

void ptdump_walk_pgd_level_debugfs(struct seq_file *m, pgd_t *pgd, bool user);

void ptdump_walk_pgd_level_checkwx(void);

void ptdump_walk_user_pgd_level_checkwx(void);



#ifdef CONFIG_DEBUG_WX

#define debug_checkwx()		ptdump_walk_pgd_level_checkwx()

#define debug_checkwx_user()	ptdump_walk_user_pgd_level_checkwx()

#else

#define debug_checkwx()		do { } while (0)

#define debug_checkwx_user()	do { } while (0)

#endif



/*

arch/x86/mm/dump_pagetables.c

+3 −3
Original line number Diff line number Diff line
@@ -569,12 +569,13 @@ void ptdump_walk_pgd_level_debugfs(struct seq_file *m, pgd_t *pgd, bool user) 
}

EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level_debugfs);



static void ptdump_walk_user_pgd_level_checkwx(void)

void ptdump_walk_user_pgd_level_checkwx(void)

{

#ifdef CONFIG_PAGE_TABLE_ISOLATION

	pgd_t *pgd = INIT_PGD;



	if (!static_cpu_has(X86_FEATURE_PTI))

	if (!(__supported_pte_mask & _PAGE_NX) ||

	    !static_cpu_has(X86_FEATURE_PTI))

		return;



	pr_info("x86/mm: Checking user space page tables\n");
@@ -586,7 +587,6 @@ static void ptdump_walk_user_pgd_level_checkwx(void) 
void ptdump_walk_pgd_level_checkwx(void)

{

	ptdump_walk_pgd_level_core(NULL, NULL, true, false);

	ptdump_walk_user_pgd_level_checkwx();

}



static int __init pt_dump_init(void)

arch/x86/mm/pti.c

+2 −0
Original line number Diff line number Diff line
@@ -646,4 +646,6 @@ void pti_finalize(void) 
	 */

	pti_clone_entry_text();

	pti_clone_kernel_text();



	debug_checkwx_user();

}