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 (see links)
To keep things simple, RISC-V follows the same.
This patch adds `ss` for shadow stack in process maps.
Links:
https://lore.kernel.org/lkml/[email protected]/#r
Signed-off-by: Deepak Gupta <[email protected]>
---
fs/proc/task_mmu.c | 3 +++
include/linux/mm.h | 11 ++++++++++-
2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 3f78ebbb795f..d9d63eb74f0d 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -702,6 +702,9 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
#endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */
#ifdef CONFIG_X86_USER_SHADOW_STACK
[ilog2(VM_SHADOW_STACK)] = "ss",
+#endif
+#ifdef CONFIG_RISCV_USER_CFI
+ [ilog2(VM_SHADOW_STACK)] = "ss",
#endif
};
size_t i;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index f5a97dec5169..64109f6c70f5 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -352,7 +352,16 @@ 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
+/*
+ * RISC-V is going along with using VM_HIGH_ARCH_5 bit position for shadow stack
+ */
+#define VM_SHADOW_STACK VM_HIGH_ARCH_5
+#endif
+
+#ifndef VM_SHADOW_STACK
# define VM_SHADOW_STACK VM_NONE
#endif
--
2.43.2
On 04.04.24 01:34, Deepak Gupta wrote:
> 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 (see links)
>
> To keep things simple, RISC-V follows the same.
> This patch adds `ss` for shadow stack in process maps.
>
> Links:
> https://lore.kernel.org/lkml/[email protected]/#r
>
> Signed-off-by: Deepak Gupta <[email protected]>
> ---
> fs/proc/task_mmu.c | 3 +++
> include/linux/mm.h | 11 ++++++++++-
> 2 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 3f78ebbb795f..d9d63eb74f0d 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -702,6 +702,9 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
> #endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */
> #ifdef CONFIG_X86_USER_SHADOW_STACK
> [ilog2(VM_SHADOW_STACK)] = "ss",
> +#endif
> +#ifdef CONFIG_RISCV_USER_CFI
> + [ilog2(VM_SHADOW_STACK)] = "ss",
> #endif
> };
> size_t i;
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index f5a97dec5169..64109f6c70f5 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -352,7 +352,16 @@ 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
> +/*
> + * RISC-V is going along with using VM_HIGH_ARCH_5 bit position for shadow stack
> + */
Wow, really?! I could never have guesses that from the code :P
Just drop that comment. Are them semantics the same as for the x86 variant documented?
("VM_SHADOW_STACK should not be set with VM_SHARED because of lack of")
I assume so. So it might now make sense to merge both paths
#if defined(CONFIG_X86_USER_SHADOW_STACK) || defined(CONFIG_RISCV_USER_CFI)
or even introduce some ARCH_HAS_SHADOW_STACK so we can remove these
arch-specific thingies here.
--
Cheers,
David / dhildenb
On Thu, Apr 04, 2024 at 08:58:06PM +0200, David Hildenbrand wrote:
> or even introduce some ARCH_HAS_SHADOW_STACK so we can remove these
> arch-specific thingies here.
It would be convenient if you could pull the ARCH_HAS_USER_SHADOW_STACK
patch out of my clone3 series to do that:
https://lore.kernel.org/all/[email protected]/
On 04.04.24 21:04, Mark Brown wrote:
> On Thu, Apr 04, 2024 at 08:58:06PM +0200, David Hildenbrand wrote:
>
>> or even introduce some ARCH_HAS_SHADOW_STACK so we can remove these
>> arch-specific thingies here.
>
> It would be convenient if you could pull the ARCH_HAS_USER_SHADOW_STACK
> patch out of my clone3 series to do that:
>
> https://lore.kernel.org/all/[email protected]/
Crazy, I completely forgot about that one. Yes!
--
Cheers,
David / dhildenb
On Thu, Apr 4, 2024 at 12:15 PM David Hildenbrand <[email protected]> wrote:
>
> On 04.04.24 21:04, Mark Brown wrote:
> > On Thu, Apr 04, 2024 at 08:58:06PM +0200, David Hildenbrand wrote:
> >
> >> or even introduce some ARCH_HAS_SHADOW_STACK so we can remove these
> >> arch-specific thingies here.
> >
> > It would be convenient if you could pull the ARCH_HAS_USER_SHADOW_STACK
> > patch out of my clone3 series to do that:
> >
> > https://lore.kernel.org/all/[email protected]/
>
> Crazy, I completely forgot about that one. Yes!
I missed that. Roger.
Will do that in the next series.
Thanks.