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Merge tag 'x86_shstk_for_6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull x86 shadow stack support from Dave Hansen:
 "This is the long awaited x86 shadow stack support, part of Intel's
  Control-flow Enforcement Technology (CET).

  CET consists of two related security features: shadow stacks and
  indirect branch tracking. This series implements just the shadow stack
  part of this feature, and just for userspace.

  The main use case for shadow stack is providing protection against
  return oriented programming attacks. It works by maintaining a
  secondary (shadow) stack using a special memory type that has
  protections against modification. When executing a CALL instruction,
  the processor pushes the return address to both the normal stack and
  to the special permission shadow stack. Upon RET, the processor pops
  the shadow stack copy and compares it to the normal stack copy.

  For more information, refer to the links below for the earlier
  versions of this patch set"

Link: https://lore.kernel.org/lkml/20220130211838.8382-1-rick.p.edgecombe@intel.com/
Link: https://lore.kernel.org/lkml/20230613001108.3040476-1-rick.p.edgecombe@intel.com/

* tag 'x86_shstk_for_6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (47 commits)
  x86/shstk: Change order of __user in type
  x86/ibt: Convert IBT selftest to asm
  x86/shstk: Don't retry vm_munmap() on -EINTR
  x86/kbuild: Fix Documentation/ reference
  x86/shstk: Move arch detail comment out of core mm
  x86/shstk: Add ARCH_SHSTK_STATUS
  x86/shstk: Add ARCH_SHSTK_UNLOCK
  x86: Add PTRACE interface for shadow stack
  selftests/x86: Add shadow stack test
  x86/cpufeatures: Enable CET CR4 bit for shadow stack
  x86/shstk: Wire in shadow stack interface
  x86: Expose thread features in /proc/$PID/status
  x86/shstk: Support WRSS for userspace
  x86/shstk: Introduce map_shadow_stack syscall
  x86/shstk: Check that signal frame is shadow stack mem
  x86/shstk: Check that SSP is aligned on sigreturn
  x86/shstk: Handle signals for shadow stack
  x86/shstk: Introduce routines modifying shstk
  x86/shstk: Handle thread shadow stack
  x86/shstk: Add user-mode shadow stack support
  ...
This commit is contained in:
Linus Torvalds
2023-08-31 12:20:12 -07:00
parent b97d64c722 1fe428d369
commit df57721f9a
118 changed files with 2790 additions and 308 deletions
Download Patch File Download Diff File Expand all files Collapse all files

47
include/linux/mm.h
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@@ -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 +341,21 @@ extern unsigned int kobjsize(const void *objp);
#endif
#endif /* CONFIG_ARCH_HAS_PKEYS */
#ifdef CONFIG_X86_USER_SHADOW_STACK
/*
* VM_SHADOW_STACK should not be set with VM_SHARED because of lack of
* support core mm.
*
* These VMAs will get a single end guard page. This helps userspace protect
* itself from attacks. A single page is enough for current shadow stack archs
* (x86). See the comments near alloc_shstk() in arch/x86/kernel/shstk.c
* for more details on the guard size.
*/
# 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)
@@ -370,7 +387,7 @@ extern unsigned int kobjsize(const void *objp);
#endif
#ifdef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR
# define VM_UFFD_MINOR_BIT 37
# define VM_UFFD_MINOR_BIT 38
# define VM_UFFD_MINOR BIT(VM_UFFD_MINOR_BIT) /* UFFD minor faults */
#else /* !CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */
# define VM_UFFD_MINOR VM_NONE
@@ -397,6 +414,8 @@ extern unsigned int kobjsize(const void *objp);
#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
#endif
#define VM_STARTGAP_FLAGS (VM_GROWSDOWN | VM_SHADOW_STACK)
#ifdef CONFIG_STACK_GROWSUP
#define VM_STACK VM_GROWSUP
#define VM_STACK_EARLY VM_GROWSDOWN
@@ -1309,7 +1328,7 @@ static inline unsigned long thp_size(struct page *page)
static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
{
if (likely(vma->vm_flags & VM_WRITE))
pte = pte_mkwrite(pte);
pte = pte_mkwrite(pte, vma);
return pte;
}
@@ -3265,7 +3284,8 @@ extern unsigned long mmap_region(struct file *file, unsigned long addr,
struct list_head *uf);
extern unsigned long do_mmap(struct file *file, unsigned long addr,
unsigned long len, unsigned long prot, unsigned long flags,
unsigned long pgoff, unsigned long *populate, struct list_head *uf);
vm_flags_t vm_flags, unsigned long pgoff, unsigned long *populate,
struct list_head *uf);
extern int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm,
unsigned long start, size_t len, struct list_head *uf,
bool unlock);
@@ -3353,15 +3373,26 @@ struct vm_area_struct *vma_lookup(struct mm_struct *mm, unsigned long addr)
return mtree_load(&mm->mm_mt, addr);
}
static inline unsigned long stack_guard_start_gap(struct vm_area_struct *vma)
{
if (vma->vm_flags & VM_GROWSDOWN)
return stack_guard_gap;
/* See reasoning around the VM_SHADOW_STACK definition */
if (vma->vm_flags & VM_SHADOW_STACK)
return PAGE_SIZE;
return 0;
}
static inline unsigned long vm_start_gap(struct vm_area_struct *vma)
{
unsigned long gap = stack_guard_start_gap(vma);
unsigned long vm_start = vma->vm_start;
if (vma->vm_flags & VM_GROWSDOWN) {
vm_start -= stack_guard_gap;
if (vm_start > vma->vm_start)
vm_start = 0;
}
vm_start -= gap;
if (vm_start > vma->vm_start)
vm_start = 0;
return vm_start;
}