linux-kernel - [PATCH v2 07/27] mm: Define VM_SHADOW

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]

Message-Id: <20240329044459.3990638-8-debug@rivosinc.com>
Date: Thu, 28 Mar 2024 21:44:39 -0700
From: Deepak Gupta <debug@...osinc.com>
To: paul.walmsley@...ive.com,
	rick.p.edgecombe@...el.com,
	broonie@...nel.org,
	Szabolcs.Nagy@....com,
	kito.cheng@...ive.com,
	keescook@...omium.org,
	ajones@...tanamicro.com,
	conor.dooley@...rochip.com,
	cleger@...osinc.com,
	atishp@...shpatra.org,
	alex@...ti.fr,
	bjorn@...osinc.com,
	alexghiti@...osinc.com,
	samuel.holland@...ive.com,
	palmer@...ive.com,
	conor@...nel.org,
	linux-doc@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-mm@...ck.org,
	linux-arch@...r.kernel.org,
	linux-kselftest@...r.kernel.org
Cc: corbet@....net,
	tech-j-ext@...ts.risc-v.org,
	palmer@...belt.com,
	aou@...s.berkeley.edu,
	robh+dt@...nel.org,
	krzysztof.kozlowski+dt@...aro.org,
	oleg@...hat.com,
	akpm@...ux-foundation.org,
	arnd@...db.de,
	ebiederm@...ssion.com,
	Liam.Howlett@...cle.com,
	vbabka@...e.cz,
	lstoakes@...il.com,
	shuah@...nel.org,
	brauner@...nel.org,
	debug@...osinc.com,
	andy.chiu@...ive.com,
	jerry.shih@...ive.com,
	hankuan.chen@...ive.com,
	greentime.hu@...ive.com,
	evan@...osinc.com,
	xiao.w.wang@...el.com,
	charlie@...osinc.com,
	apatel@...tanamicro.com,
	mchitale@...tanamicro.com,
	dbarboza@...tanamicro.com,
	sameo@...osinc.com,
	shikemeng@...weicloud.com,
	willy@...radead.org,
	vincent.chen@...ive.com,
	guoren@...nel.org,
	samitolvanen@...gle.com,
	songshuaishuai@...ylab.org,
	gerg@...nel.org,
	heiko@...ech.de,
	bhe@...hat.com,
	jeeheng.sia@...rfivetech.com,
	cyy@...self.name,
	maskray@...gle.com,
	ancientmodern4@...il.com,
	mathis.salmen@...sal.de,
	cuiyunhui@...edance.com,
	bgray@...ux.ibm.com,
	mpe@...erman.id.au,
	baruch@...s.co.il,
	alx@...nel.org,
	david@...hat.com,
	catalin.marinas@....com,
	revest@...omium.org,
	josh@...htriplett.org,
	shr@...kernel.io,
	deller@....de,
	omosnace@...hat.com,
	ojeda@...nel.org,
	jhubbard@...dia.com
Subject: [PATCH v2 07/27] mm: Define VM_SHADOW_STACK for RISC-V

VM_SHADOW_STACK is defined by x86 as vm flag to mark a shadow stack vma.

x86 uses VM_HIGH_ARCH_5 bit but that limits shadow stack vma to 64bit only.
arm64 follows same path
https://lore.kernel.org/lkml/20231009-arm64-gcs-v6-12-78e55deaa4dd@kernel.org/#r

To keep things simple, RISC-V follows the same.

Signed-off-by: Deepak Gupta <debug@...osinc.com>
---
 include/linux/mm.h | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index f5a97dec5169..225af437ecba 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -352,7 +352,25 @@ extern unsigned int kobjsize(const void *objp);
  * for more details on the guard size.
  */
 # define VM_SHADOW_STACK	VM_HIGH_ARCH_5
-#else
+#endif
+
+#ifdef CONFIG_RISCV_USER_CFI
+/*
+ * On RISC-V pte encodings for shadow stack is R=0, W=1, X=0 and thus RISCV
+ * choosing to use similar mechanism on vm_flags where VM_WRITE only means
+ * VM_SHADOW_STACK. RISCV as well doesn't support VM_SHADOW_STACK to be set
+ * with VM_SHARED.
+ */
+#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
+
+#ifndef VM_SHADOW_STACK
 # define VM_SHADOW_STACK	VM_NONE
 #endif
 
-- 
2.43.2