diff mbox series

[v28,14/32] mm: Introduce VM_SHADOW_STACK for shadow stack memory

Message ID 20210722205219.7934-15-yu-cheng.yu@intel.com (mailing list archive)
State New
Headers show
Series Control-flow Enforcement: Shadow Stack | expand

Commit Message

Yu-cheng Yu July 22, 2021, 8:52 p.m. UTC 
A shadow stack PTE must be read-only and have _PAGE_DIRTY set.  However,
read-only and Dirty PTEs also exist for copy-on-write (COW) pages.  These
two cases are handled differently for page faults.  Introduce
VM_SHADOW_STACK to track shadow stack VMAs.

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Kees Cook <keescook@chromium.org>
---
 Documentation/filesystems/proc.rst | 1 +
 arch/x86/mm/mmap.c                 | 2 ++
 fs/proc/task_mmu.c                 | 3 +++
 include/linux/mm.h                 | 8 ++++++++
 4 files changed, 14 insertions(+)

Comments

Borislav Petkov Aug. 16, 2021, 4:35 p.m. UTC | #1 
On Thu, Jul 22, 2021 at 01:52:01PM -0700, Yu-cheng Yu wrote:
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index eb97468dfe4c..02c70198b989 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -662,6 +662,9 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
>  #ifdef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR
>  		[ilog2(VM_UFFD_MINOR)]	= "ui",
>  #endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */
> +#ifdef CONFIG_ARCH_HAS_SHADOW_STACK
> +		[ilog2(VM_SHADOW_STACK)]= "ss",
> +#endif


ERROR: spaces required around that '=' (ctx:VxW)
#109: FILE: fs/proc/task_mmu.c:666:
+		[ilog2(VM_SHADOW_STACK)]= "ss",
 		                        ^

total: 1 errors, 0 warnings, 49 lines checked

Please integrate scripts/checkpatch.pl into your patch creation
workflow. Some of the warnings/errors *actually* make sense.
Yu-cheng Yu Aug. 17, 2021, 6:35 p.m. UTC | #2 
On 8/16/2021 9:35 AM, Borislav Petkov wrote:
> On Thu, Jul 22, 2021 at 01:52:01PM -0700, Yu-cheng Yu wrote:
>> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
>> index eb97468dfe4c..02c70198b989 100644
>> --- a/fs/proc/task_mmu.c
>> +++ b/fs/proc/task_mmu.c
>> @@ -662,6 +662,9 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
>>   #ifdef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR
>>   		[ilog2(VM_UFFD_MINOR)]	= "ui",
>>   #endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */
>> +#ifdef CONFIG_ARCH_HAS_SHADOW_STACK
>> +		[ilog2(VM_SHADOW_STACK)]= "ss",
>> +#endif
> 
> 
> ERROR: spaces required around that '=' (ctx:VxW)
> #109: FILE: fs/proc/task_mmu.c:666:
> +		[ilog2(VM_SHADOW_STACK)]= "ss",
>   		                        ^
> 
> total: 1 errors, 0 warnings, 49 lines checked
> 
> Please integrate scripts/checkpatch.pl into your patch creation
> workflow. Some of the warnings/errors *actually* make sense.
> 

I will add a space there.

Thanks,
Yu-cheng
diff mbox series

Patch

diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
index 042c418f4090..3473f1aa7e89 100644
--- a/Documentation/filesystems/proc.rst
+++ b/Documentation/filesystems/proc.rst
@@ -553,6 +553,7 @@  encoded manner. The codes are the following:
     mt    arm64 MTE allocation tags are enabled
     um    userfaultfd missing tracking
     uw    userfaultfd wr-protect tracking
+    ss    shadow stack page
     ==    =======================================
 
 Note that there is no guarantee that every flag and associated mnemonic will
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index c90c20904a60..f3f52c5e2fd6 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -165,6 +165,8 @@  unsigned long get_mmap_base(int is_legacy)
 
 const char *arch_vma_name(struct vm_area_struct *vma)
 {
+	if (vma->vm_flags & VM_SHADOW_STACK)
+		return "[shadow stack]";
 	return NULL;
 }
 
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index eb97468dfe4c..02c70198b989 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -662,6 +662,9 @@  static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
 #ifdef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR
 		[ilog2(VM_UFFD_MINOR)]	= "ui",
 #endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */
+#ifdef CONFIG_ARCH_HAS_SHADOW_STACK
+		[ilog2(VM_SHADOW_STACK)]= "ss",
+#endif
 	};
 	size_t i;
 
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 1d4e5012c27d..4a9985e50819 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -319,11 +319,13 @@  extern unsigned int kobjsize(const void *objp);
 #define VM_HIGH_ARCH_BIT_2	34	/* bit only usable on 64-bit architectures */
 #define VM_HIGH_ARCH_BIT_3	35	/* bit only usable on 64-bit architectures */
 #define VM_HIGH_ARCH_BIT_4	36	/* bit only usable on 64-bit architectures */
+#define VM_HIGH_ARCH_BIT_5	37	/* bit only usable on 64-bit architectures */
 #define VM_HIGH_ARCH_0	BIT(VM_HIGH_ARCH_BIT_0)
 #define VM_HIGH_ARCH_1	BIT(VM_HIGH_ARCH_BIT_1)
 #define VM_HIGH_ARCH_2	BIT(VM_HIGH_ARCH_BIT_2)
 #define VM_HIGH_ARCH_3	BIT(VM_HIGH_ARCH_BIT_3)
 #define VM_HIGH_ARCH_4	BIT(VM_HIGH_ARCH_BIT_4)
+#define VM_HIGH_ARCH_5	BIT(VM_HIGH_ARCH_BIT_5)
 #endif /* CONFIG_ARCH_USES_HIGH_VMA_FLAGS */
 
 #ifdef CONFIG_ARCH_HAS_PKEYS
@@ -339,6 +341,12 @@  extern unsigned int kobjsize(const void *objp);
 #endif
 #endif /* CONFIG_ARCH_HAS_PKEYS */
 
+#ifdef CONFIG_X86_SHADOW_STACK
+# define VM_SHADOW_STACK	VM_HIGH_ARCH_5
+#else
+# define VM_SHADOW_STACK	VM_NONE
+#endif
+
 #if defined(CONFIG_X86)
 # define VM_PAT		VM_ARCH_1	/* PAT reserves whole VMA at once (x86) */
 #elif defined(CONFIG_PPC)