lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Wed, 24 Jan 2024 22:21:34 -0800
From: debug@...osinc.com
To: rick.p.edgecombe@...el.com,
	broonie@...nel.org,
	Szabolcs.Nagy@....com,
	kito.cheng@...ive.com,
	keescook@...omium.org,
	ajones@...tanamicro.com,
	paul.walmsley@...ive.com,
	palmer@...belt.com,
	conor.dooley@...rochip.com,
	cleger@...osinc.com,
	atishp@...shpatra.org,
	alex@...ti.fr,
	bjorn@...osinc.com,
	alexghiti@...osinc.com
Cc: corbet@....net,
	aou@...s.berkeley.edu,
	oleg@...hat.com,
	akpm@...ux-foundation.org,
	arnd@...db.de,
	ebiederm@...ssion.com,
	shuah@...nel.org,
	brauner@...nel.org,
	debug@...osinc.com,
	guoren@...nel.org,
	samitolvanen@...gle.com,
	evan@...osinc.com,
	xiao.w.wang@...el.com,
	apatel@...tanamicro.com,
	mchitale@...tanamicro.com,
	waylingii@...il.com,
	greentime.hu@...ive.com,
	heiko@...ech.de,
	jszhang@...nel.org,
	shikemeng@...weicloud.com,
	david@...hat.com,
	charlie@...osinc.com,
	panqinglin2020@...as.ac.cn,
	willy@...radead.org,
	vincent.chen@...ive.com,
	andy.chiu@...ive.com,
	gerg@...nel.org,
	jeeheng.sia@...rfivetech.com,
	mason.huo@...rfivetech.com,
	ancientmodern4@...il.com,
	mathis.salmen@...sal.de,
	cuiyunhui@...edance.com,
	bhe@...hat.com,
	chenjiahao16@...wei.com,
	ruscur@...sell.cc,
	bgray@...ux.ibm.com,
	alx@...nel.org,
	baruch@...s.co.il,
	zhangqing@...ngson.cn,
	catalin.marinas@....com,
	revest@...omium.org,
	josh@...htriplett.org,
	joey.gouly@....com,
	shr@...kernel.io,
	omosnace@...hat.com,
	ojeda@...nel.org,
	jhubbard@...dia.com,
	linux-doc@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	linux-arch@...r.kernel.org,
	linux-kselftest@...r.kernel.org
Subject: [RFC PATCH v1 09/28] mm: abstract shadow stack vma behind `arch_is_shadow_stack`

From: Deepak Gupta <debug@...osinc.com>

x86 has used VM_SHADOW_STACK (alias to VM_HIGH_ARCH_5) to encode shadow
stack VMA. VM_SHADOW_STACK is thus not possible on 32bit. Some arches may
need a way to encode shadow stack on 32bit and 64bit both and they may
encode this information differently in VMAs.

This patch changes checks of VM_SHADOW_STACK flag in generic code to call
to a function `arch_is_shadow_stack` which will return true if arch
supports shadow stack and vma is shadow stack else stub returns false.

There was a suggestion to name it as `vma_is_shadow_stack`. I preferred to
keep `arch` prefix in there because it's each arch specific.

Signed-off-by: Deepak Gupta <debug@...osinc.com>
---
 include/linux/mm.h | 18 +++++++++++++++++-
 mm/gup.c           |  5 +++--
 mm/internal.h      |  2 +-
 3 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index dfe0e8118669..15c70fc677a3 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -352,6 +352,10 @@ extern unsigned int kobjsize(const void *objp);
  * for more details on the guard size.
  */
 # define VM_SHADOW_STACK	VM_HIGH_ARCH_5
+static inline bool arch_is_shadow_stack(vm_flags_t vm_flags)
+{
+	return (vm_flags & VM_SHADOW_STACK);
+}
 #endif
 
 #ifdef CONFIG_RISCV_USER_CFI
@@ -362,10 +366,22 @@ extern unsigned int kobjsize(const void *objp);
  * with VM_SHARED.
  */
 #define VM_SHADOW_STACK	VM_WRITE
+
+static inline bool arch_is_shadow_stack(vm_flags_t vm_flags)
+{
+	return ((vm_flags & (VM_WRITE | VM_READ | VM_EXEC)) == VM_WRITE);
+}
+
 #endif
 
 #ifndef VM_SHADOW_STACK
 # define VM_SHADOW_STACK	VM_NONE
+
+static inline bool arch_is_shadow_stack(vm_flags_t vm_flags)
+{
+	return false;
+}
+
 #endif
 
 #if defined(CONFIG_X86)
@@ -3464,7 +3480,7 @@ static inline unsigned long stack_guard_start_gap(struct vm_area_struct *vma)
 		return stack_guard_gap;
 
 	/* See reasoning around the VM_SHADOW_STACK definition */
-	if (vma->vm_flags & VM_SHADOW_STACK)
+	if (vma->vm_flags && arch_is_shadow_stack(vma->vm_flags))
 		return PAGE_SIZE;
 
 	return 0;
diff --git a/mm/gup.c b/mm/gup.c
index 231711efa390..45798782ed2c 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1051,7 +1051,7 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
 		    !writable_file_mapping_allowed(vma, gup_flags))
 			return -EFAULT;
 
-		if (!(vm_flags & VM_WRITE) || (vm_flags & VM_SHADOW_STACK)) {
+		if (!(vm_flags & VM_WRITE) || arch_is_shadow_stack(vm_flags)) {
 			if (!(gup_flags & FOLL_FORCE))
 				return -EFAULT;
 			/* hugetlb does not support FOLL_FORCE|FOLL_WRITE. */
@@ -1069,7 +1069,8 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
 			if (!is_cow_mapping(vm_flags))
 				return -EFAULT;
 		}
-	} else if (!(vm_flags & VM_READ)) {
+	} else if (!(vm_flags & VM_READ) && !arch_is_shadow_stack(vm_flags)) {
+	/* reads allowed if its shadow stack vma */
 		if (!(gup_flags & FOLL_FORCE))
 			return -EFAULT;
 		/*
diff --git a/mm/internal.h b/mm/internal.h
index b61034bd50f5..0abf00c93fe1 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -572,7 +572,7 @@ static inline bool is_exec_mapping(vm_flags_t flags)
  */
 static inline bool is_stack_mapping(vm_flags_t flags)
 {
-	return ((flags & VM_STACK) == VM_STACK) || (flags & VM_SHADOW_STACK);
+	return ((flags & VM_STACK) == VM_STACK) || arch_is_shadow_stack(flags);
 }
 
 /*
-- 
2.43.0


Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ