From: Deepak Gupta <debug@rivosinc.com>
To: Alexandre Ghiti <alex@ghiti.fr>
Cc: paul.walmsley@sifive.com, rick.p.edgecombe@intel.com,
broonie@kernel.org, Szabolcs.Nagy@arm.com, kito.cheng@sifive.com,
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Subject: Re: [PATCH v3 10/29] riscv/mm : ensure PROT_WRITE leads to VM_READ | VM_WRITE
Date: Mon, 13 May 2024 11:29:27 -0700 [thread overview]
Message-ID: <ZkJcB5u+0bZ2KsS+@debug.ba.rivosinc.com> (raw)
In-Reply-To: <c759444d-fe84-4a61-8448-80fb692c7904@ghiti.fr>
On Sun, May 12, 2024 at 06:24:45PM +0200, Alexandre Ghiti wrote:
>Hi Deepak,
>
>On 04/04/2024 01:34, Deepak Gupta wrote:
>>`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@rivosinc.com>
>>---
>> arch/riscv/include/asm/mman.h | 24 ++++++++++++++++++++++++
>> arch/riscv/include/asm/pgtable.h | 1 +
>> arch/riscv/kernel/sys_riscv.c | 11 +++++++++++
>> arch/riscv/mm/init.c | 2 +-
>> mm/mmap.c | 1 +
>> 5 files changed, 38 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 6066822e7396..4d5983bc6766 100644
>>--- a/arch/riscv/include/asm/pgtable.h
>>+++ b/arch/riscv/include/asm/pgtable.h
>>@@ -184,6 +184,7 @@ extern struct pt_alloc_ops pt_ops __initdata;
>> #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 f1c1416a9f1e..846c36b1b3d5 100644
>>--- a/arch/riscv/kernel/sys_riscv.c
>>+++ b/arch/riscv/kernel/sys_riscv.c
>>@@ -8,6 +8,8 @@
>> #include <linux/syscalls.h>
>> #include <asm/cacheflush.h>
>> #include <asm-generic/mman-common.h>
>>+#include <vdso/vsyscall.h>
>>+#include <asm/mman.h>
>> static long riscv_sys_mmap(unsigned long addr, unsigned long len,
>> unsigned long prot, unsigned long flags,
>>@@ -17,6 +19,15 @@ static long riscv_sys_mmap(unsigned long addr, unsigned long len,
>> if (unlikely(offset & (~PAGE_MASK >> page_shift_offset)))
>> return -EINVAL;
>>+ /*
>>+ * If only 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 fa34cf55037b..98e5ece4052a 100644
>>--- a/arch/riscv/mm/init.c
>>+++ b/arch/riscv/mm/init.c
>>@@ -299,7 +299,7 @@ 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 d89770eaab6b..57a974f49b00 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>
>
>
>What happens if someone restricts the permission to PROT_WRITE using
>mprotect()? I would say this is an issue since it would turn the pages
>into shadow stack pages.
look at this patch in this patch series.
"riscv/mm : ensure PROT_WRITE leads to VM_READ | VM_WRITE"
It implements `arch_calc_vm_prot_bits` for risc-v and enforces that incoming
PROT_WRITE is converted to VM_READ | VM_WRITE. And thus it'll become read/write
memory. This way `mprotect` can be used to convert a shadow stack page to
read/write memory but not a regular memory to shadow stack page.
>
>
next prev parent reply other threads:[~2024-05-13 18:29 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-03 23:34 [PATCH v3 00/29] riscv control-flow integrity for usermode Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 01/29] riscv: envcfg save and restore on task switching Deepak Gupta
2024-05-09 0:10 ` Charlie Jenkins
2024-05-09 19:00 ` Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 02/29] riscv: define default value for envcfg for task Deepak Gupta
2024-05-10 22:33 ` Charlie Jenkins
2024-05-13 18:33 ` Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 03/29] riscv/Kconfig: enable HAVE_EXIT_THREAD for riscv Deepak Gupta
2024-05-10 22:36 ` Charlie Jenkins
2024-04-03 23:34 ` [PATCH v3 04/29] riscv: zicfilp / zicfiss in dt-bindings (extensions.yaml) Deepak Gupta
2024-04-10 11:58 ` Rob Herring
2024-04-10 21:37 ` Deepak Gupta
2024-04-15 19:41 ` Rob Herring
[not found] ` <Zh6c0FH2OvrfDLje@debug.ba.rivosinc.com>
2024-05-09 18:14 ` Conor Dooley
2024-05-09 18:46 ` Deepak Gupta
2024-05-09 20:32 ` Conor Dooley
2024-05-09 23:26 ` Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 05/29] riscv: zicfiss / zicfilp enumeration Deepak Gupta
2024-05-09 0:00 ` Andy Chiu
2024-05-09 0:07 ` Charlie Jenkins
2024-04-03 23:34 ` [PATCH v3 06/29] riscv: zicfiss / zicfilp extension csr and bit definitions Deepak Gupta
2024-05-10 22:37 ` Charlie Jenkins
2024-04-03 23:34 ` [PATCH v3 07/29] riscv: usercfi state for task and save/restore of CSR_SSP on trap entry/exit Deepak Gupta
2024-05-10 22:51 ` Charlie Jenkins
2024-04-03 23:34 ` [PATCH v3 08/29] mm: Define VM_SHADOW_STACK for RISC-V Deepak Gupta
[not found] ` <8fb37319-288c-4f77-9cd7-92f17bb567ee@redhat.com>
2024-04-04 19:04 ` Mark Brown
2024-04-04 19:15 ` David Hildenbrand
2024-04-04 19:21 ` Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 09/29] mm: abstract shadow stack vma behind `vma_is_shadow_stack` Deepak Gupta
[not found] ` <c438ea3a-24bc-470b-a2eb-6e7517bd4362@redhat.com>
2024-04-04 21:39 ` Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 10/29] riscv/mm : ensure PROT_WRITE leads to VM_READ | VM_WRITE Deepak Gupta
2024-05-10 21:02 ` Charlie Jenkins
2024-05-13 17:47 ` Deepak Gupta
2024-05-13 18:36 ` Charlie Jenkins
2024-05-13 18:41 ` Deepak Gupta
2024-05-13 21:26 ` Charlie Jenkins
2024-05-12 16:24 ` Alexandre Ghiti
2024-05-13 18:29 ` Deepak Gupta [this message]
2024-04-03 23:34 ` [PATCH v3 11/29] riscv mm: manufacture shadow stack pte Deepak Gupta
2024-05-12 16:26 ` Alexandre Ghiti
2024-04-03 23:35 ` [PATCH v3 12/29] riscv mmu: teach pte_mkwrite to manufacture shadow stack PTEs Deepak Gupta
2024-05-12 16:28 ` Alexandre Ghiti
2024-05-13 17:33 ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 13/29] riscv mmu: write protect and shadow stack Deepak Gupta
2024-05-12 16:31 ` Alexandre Ghiti
2024-05-13 17:32 ` Deepak Gupta
2024-05-23 14:59 ` Alexandre Ghiti
2024-05-24 7:16 ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 14/29] riscv/mm: Implement map_shadow_stack() syscall Deepak Gupta
2024-05-12 16:50 ` Alexandre Ghiti
2024-05-13 17:25 ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 15/29] riscv/shstk: If needed allocate a new shadow stack on clone Deepak Gupta
2024-05-12 17:05 ` Alexandre Ghiti
2024-05-13 17:10 ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 16/29] prctl: arch-agnostic prctl for shadow stack Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 17/29] prctl: arch-agnostic prctl for indirect branch tracking Deepak Gupta
2024-05-10 23:29 ` Charlie Jenkins
2024-05-13 18:31 ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 18/29] riscv: Implements arch agnostic shadow stack prctls Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 19/29] riscv: Implements arch agnostic indirect branch tracking prctls Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 20/29] riscv/kernel: update __show_regs to print shadow stack register Deepak Gupta
2024-05-12 17:10 ` Alexandre Ghiti
2024-04-03 23:35 ` [PATCH v3 21/29] riscv/traps: Introduce software check exception Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 22/29] riscv sigcontext: adding cfi state field in sigcontext Deepak Gupta
2024-05-24 9:46 ` Andy Chiu
2024-05-24 19:11 ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 23/29] riscv signal: Save and restore of shadow stack for signal Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 24/29] riscv/ptrace: riscv cfi status and state via ptrace and in core files Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 25/29] riscv/hwprobe: zicfilp / zicfiss enumeration in hwprobe Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 26/29] riscv: create a config for shadow stack and landing pad instr support Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 27/29] riscv: Documentation for landing pad / indirect branch tracking Deepak Gupta
2024-05-10 20:30 ` Charlie Jenkins
2024-05-13 17:07 ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 28/29] riscv: Documentation for shadow stack on riscv Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 29/29] kselftest/riscv: kselftest for user mode cfi Deepak Gupta
2024-05-09 18:21 ` Charlie Jenkins
2024-05-09 19:16 ` Deepak Gupta
2024-05-10 1:20 ` Charlie Jenkins
2024-05-09 0:33 ` [PATCH v3 00/29] riscv control-flow integrity for usermode Charlie Jenkins
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