linux-kernel - Re: [RFC PATCH v1 09/28] mm: abstract shadow stack vma behind `arch_is_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: <ZbKVNm5ubV8yQtSE@debug.ba.rivosinc.com>
Date: Thu, 25 Jan 2024 09:07:02 -0800
From: Deepak Gupta <debug@...osinc.com>
To: David Hildenbrand <david@...hat.com>
Cc: 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, 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,
	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, 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: Re: [RFC PATCH v1 09/28] mm: abstract shadow stack vma behind
 `arch_is_shadow_stack`

On Thu, Jan 25, 2024 at 09:18:07AM +0100, David Hildenbrand wrote:
>On 25.01.24 07:21, debug@...osinc.com wrote:
>>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);
>>+}
>>+
>
>Please no such hacks just to work around the 32bit vmflags limitation.

As I said in another response. Noted.
And if there're no takers for 32bit on riscv (which highly likely is the case)
This will go away in next version of patchsets.

>
>-- 
>Cheers,
>
>David / dhildenb
>