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

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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: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Thomas 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
This commit is contained in:
Joerg Roedel 2018-08-08 13:16:40 +02:00 committed by Thomas Gleixner
parent a29dba161a
commit d878efce73
3 changed files with 10 additions and 5 deletions
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7
arch/x86/include/asm/pgtable.h
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@ -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(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_debugfs(struct seq_file *m, pgd_t *pgd, bool user);
void ptdump_walk_pgd_level_checkwx(void); void ptdump_walk_pgd_level_checkwx(void);
void ptdump_walk_user_pgd_level_checkwx(void);
#ifdef CONFIG_DEBUG_WX #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 #else
#define debug_checkwx() do { } while (0) #define debug_checkwx() do { } while (0)
#define debug_checkwx_user() do { } while (0)
#endif #endif
/* /*

6
arch/x86/mm/dump_pagetables.c
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@ -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); 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 #ifdef CONFIG_PAGE_TABLE_ISOLATION
pgd_t *pgd = INIT_PGD; 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; return;
pr_info("x86/mm: Checking user space page tables\n"); 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) void ptdump_walk_pgd_level_checkwx(void)
{ {
ptdump_walk_pgd_level_core(NULL, NULL, true, false); ptdump_walk_pgd_level_core(NULL, NULL, true, false);
ptdump_walk_user_pgd_level_checkwx();
} }
static int __init pt_dump_init(void) static int __init pt_dump_init(void)

2
arch/x86/mm/pti.c
View File

@ -646,4 +646,6 @@ void pti_finalize(void)
*/ */
pti_clone_entry_text(); pti_clone_entry_text();
pti_clone_kernel_text(); pti_clone_kernel_text();
debug_checkwx_user();
} }