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: <20240912231650.3740732-12-debug@rivosinc.com>
Date: Thu, 12 Sep 2024 16:16:30 -0700
From: Deepak Gupta <debug@...osinc.com>
To: paul.walmsley@...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-fsdevel@...r.kernel.org,
	linux-mm@...ck.org,
	linux-arch@...r.kernel.org,
	linux-kselftest@...r.kernel.org
Cc: corbet@....net,
	palmer@...belt.com,
	aou@...s.berkeley.edu,
	robh@...nel.org,
	krzk+dt@...nel.org,
	oleg@...hat.com,
	tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	x86@...nel.org,
	hpa@...or.com,
	peterz@...radead.org,
	akpm@...ux-foundation.org,
	arnd@...db.de,
	ebiederm@...ssion.com,
	kees@...nel.org,
	Liam.Howlett@...cle.com,
	vbabka@...e.cz,
	lorenzo.stoakes@...cle.com,
	shuah@...nel.org,
	brauner@...nel.org,
	samuel.holland@...ive.com,
	debug@...osinc.com,
	andy.chiu@...ive.com,
	jerry.shih@...ive.com,
	greentime.hu@...ive.com,
	charlie@...osinc.com,
	evan@...osinc.com,
	cleger@...osinc.com,
	xiao.w.wang@...el.com,
	ajones@...tanamicro.com,
	anup@...infault.org,
	mchitale@...tanamicro.com,
	atishp@...osinc.com,
	sameo@...osinc.com,
	bjorn@...osinc.com,
	alexghiti@...osinc.com,
	david@...hat.com,
	libang.li@...group.com,
	jszhang@...nel.org,
	leobras@...hat.com,
	guoren@...nel.org,
	samitolvanen@...gle.com,
	songshuaishuai@...ylab.org,
	costa.shul@...hat.com,
	bhe@...hat.com,
	zong.li@...ive.com,
	puranjay@...nel.org,
	namcaov@...il.com,
	antonb@...storrent.com,
	sorear@...tmail.com,
	quic_bjorande@...cinc.com,
	ancientmodern4@...il.com,
	ben.dooks@...ethink.co.uk,
	quic_zhonhan@...cinc.com,
	cuiyunhui@...edance.com,
	yang.lee@...ux.alibaba.com,
	ke.zhao@...ngroup.cn,
	sunilvl@...tanamicro.com,
	tanzhasanwork@...il.com,
	schwab@...e.de,
	dawei.li@...ngroup.cn,
	rppt@...nel.org,
	willy@...radead.org,
	usama.anjum@...labora.com,
	osalvador@...e.de,
	ryan.roberts@....com,
	andrii@...nel.org,
	alx@...nel.org,
	catalin.marinas@....com,
	broonie@...nel.org,
	revest@...omium.org,
	bgray@...ux.ibm.com,
	deller@....de,
	zev@...ilderbeest.net
Subject: [PATCH v4 11/30] riscv/mm : ensure PROT_WRITE leads to VM_READ | VM_WRITE

`arch_calc_vm_prot_bits` is implemented on risc-v to return VM_READ |
VM_WRITE if PROT_WRITE is specified. Similarly `riscv_sys_mmap` is
updated to convert all incoming PROT_WRITE to (PROT_WRITE | PROT_READ).
This is to make sure that any existing apps using PROT_WRITE still work.

Earlier `protection_map[VM_WRITE]` used to pick read-write PTE encodings.
Now `protection_map[VM_WRITE]` will always pick PAGE_SHADOWSTACK PTE
encodings for shadow stack. Above changes ensure that existing apps
continue to work because underneath kernel will be picking
`protection_map[VM_WRITE|VM_READ]` PTE encodings.

Signed-off-by: Deepak Gupta <debug@...osinc.com>
---
 arch/riscv/include/asm/mman.h    | 24 ++++++++++++++++++++++++
 arch/riscv/include/asm/pgtable.h |  1 +
 arch/riscv/kernel/sys_riscv.c    | 10 ++++++++++
 arch/riscv/mm/init.c             |  2 +-
 mm/mmap.c                        |  1 +
 5 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 arch/riscv/include/asm/mman.h

diff --git a/arch/riscv/include/asm/mman.h b/arch/riscv/include/asm/mman.h
new file mode 100644
index 000000000000..ef9fedf32546
--- /dev/null
+++ b/arch/riscv/include/asm/mman.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_MMAN_H__
+#define __ASM_MMAN_H__
+
+#include <linux/compiler.h>
+#include <linux/types.h>
+#include <uapi/asm/mman.h>
+
+static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot,
+	unsigned long pkey __always_unused)
+{
+	unsigned long ret = 0;
+
+	/*
+	 * If PROT_WRITE was specified, force it to VM_READ | VM_WRITE.
+	 * Only VM_WRITE means shadow stack.
+	 */
+	if (prot & PROT_WRITE)
+		ret = (VM_READ | VM_WRITE);
+	return ret;
+}
+#define arch_calc_vm_prot_bits(prot, pkey) arch_calc_vm_prot_bits(prot, pkey)
+
+#endif /* ! __ASM_MMAN_H__ */
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 089f3c9f56a3..af4337774fe5 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -181,6 +181,7 @@ extern struct pt_alloc_ops pt_ops __meminitdata;
 #define PAGE_READ_EXEC		__pgprot(_PAGE_BASE | _PAGE_READ | _PAGE_EXEC)
 #define PAGE_WRITE_EXEC		__pgprot(_PAGE_BASE | _PAGE_READ |	\
 					 _PAGE_EXEC | _PAGE_WRITE)
+#define PAGE_SHADOWSTACK       __pgprot(_PAGE_BASE | _PAGE_WRITE)
 
 #define PAGE_COPY		PAGE_READ
 #define PAGE_COPY_EXEC		PAGE_READ_EXEC
diff --git a/arch/riscv/kernel/sys_riscv.c b/arch/riscv/kernel/sys_riscv.c
index d77afe05578f..43a448bf254b 100644
--- a/arch/riscv/kernel/sys_riscv.c
+++ b/arch/riscv/kernel/sys_riscv.c
@@ -7,6 +7,7 @@
 
 #include <linux/syscalls.h>
 #include <asm/cacheflush.h>
+#include <asm-generic/mman-common.h>
 
 static long riscv_sys_mmap(unsigned long addr, unsigned long len,
 			   unsigned long prot, unsigned long flags,
@@ -16,6 +17,15 @@ static long riscv_sys_mmap(unsigned long addr, unsigned long len,
 	if (unlikely(offset & (~PAGE_MASK >> page_shift_offset)))
 		return -EINVAL;
 
+	/*
+	 * If PROT_WRITE is specified then extend that to PROT_READ
+	 * protection_map[VM_WRITE] is now going to select shadow stack encodings.
+	 * So specifying PROT_WRITE actually should select protection_map [VM_WRITE | VM_READ]
+	 * If user wants to create shadow stack then they should use `map_shadow_stack` syscall.
+	 */
+	if (unlikely((prot & PROT_WRITE) && !(prot & PROT_READ)))
+		prot |= PROT_READ;
+
 	return ksys_mmap_pgoff(addr, len, prot, flags, fd,
 			       offset >> (PAGE_SHIFT - page_shift_offset));
 }
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index eb0649a61b4c..000b51c26943 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -324,7 +324,7 @@ pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
 static const pgprot_t protection_map[16] = {
 	[VM_NONE]					= PAGE_NONE,
 	[VM_READ]					= PAGE_READ,
-	[VM_WRITE]					= PAGE_COPY,
+	[VM_WRITE]					= PAGE_SHADOWSTACK,
 	[VM_WRITE | VM_READ]				= PAGE_COPY,
 	[VM_EXEC]					= PAGE_EXEC,
 	[VM_EXEC | VM_READ]				= PAGE_READ_EXEC,
diff --git a/mm/mmap.c b/mm/mmap.c
index d0dfc85b209b..04023a464fac 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -47,6 +47,7 @@
 #include <linux/oom.h>
 #include <linux/sched/mm.h>
 #include <linux/ksm.h>
+#include <linux/processor.h>
 
 #include <linux/uaccess.h>
 #include <asm/cacheflush.h>
-- 
2.45.0


Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ