lkml.org 
[lkml]   [2018]   [Aug]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] x86/mm/pti: Move user W+X check into pti_finalize()
Date
From: Joerg Roedel <jroedel@suse.de>

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.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
arch/x86/include/asm/pgtable.h | 7 +++++--
arch/x86/mm/dump_pagetables.c | 3 +--
arch/x86/mm/pti.c | 2 ++
3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index e39088cb..a1cb333 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -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() 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() do { } while (0)
+#define debug_checkwx_user() do { } while (0)
#endif

/*
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index ccd92c4..b8ab901 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -569,7 +569,7 @@ 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;
@@ -586,7 +586,6 @@ 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)
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index 69a9d60..026a89a 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -628,4 +628,6 @@ void pti_finalize(void)
*/
pti_clone_entry_text();
pti_clone_kernel_text();
+
+ debug_checkwx_user();
}
--
2.7.4
\
 
 \ /
  Last update: 2018-08-08 13:23    [W:0.069 / U:15.036 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site