[PATCH v6 3/7] mseal, system mappings: enable x86-64

jeffxu
2025-02-24T17:45:23Z

From: Jeff Xu <jeffxu@chromium.org>

Provide support for CONFIG_MSEAL_SYSTEM_MAPPINGS on x86-64,
covering the vdso, vvar, vvar_vclock.

Production release testing passes on Android and Chrome OS.

Signed-off-by: Jeff Xu <jeffxu@chromium.org>
---
arch/x86/Kconfig | 1 +
arch/x86/entry/vdso/vma.c | 16 ++++++++++------
2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 87198d957e2f..8fa17032ca46 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -26,6 +26,7 @@ config X86_64
depends on 64BIT
# Options that are inherently 64-bit kernel only:
select ARCH_HAS_GIGANTIC_PAGE
+ select ARCH_HAS_MSEAL_SYSTEM_MAPPINGS
select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
select ARCH_SUPPORTS_PER_VMA_LOCK
select ARCH_SUPPORTS_HUGE_PFNMAP if TRANSPARENT_HUGEPAGE
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 39e6efc1a9ca..54677964d0b5 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -247,6 +247,7 @@ static int map_vdso(const struct vdso_image *image, unsigned long addr)
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
unsigned long text_start;
+ unsigned long vm_flags;
int ret = 0;

if (mmap_write_lock_killable(mm))
@@ -264,11 +265,12 @@ static int map_vdso(const struct vdso_image *image, unsigned long addr)
/*
* MAYWRITE to allow gdb to COW and set breakpoints
*/
+ vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC;
+ vm_flags |= MSEAL_SYSTEM_MAPPINGS_VM_FLAG;
vma = _install_special_mapping(mm,
text_start,
image->size,
- VM_READ|VM_EXEC|
- VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
+ vm_flags,
&vdso_mapping);

if (IS_ERR(vma)) {
@@ -276,11 +278,12 @@ static int map_vdso(const struct vdso_image *image, unsigned long addr)
goto up_fail;
}

+ vm_flags = VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|VM_PFNMAP;
+ vm_flags |= MSEAL_SYSTEM_MAPPINGS_VM_FLAG;
vma = _install_special_mapping(mm,
addr,
(__VVAR_PAGES - VDSO_NR_VCLOCK_PAGES) * PAGE_SIZE,
- VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|
- VM_PFNMAP,
+ vm_flags,
&vvar_mapping);

if (IS_ERR(vma)) {
@@ -289,11 +292,12 @@ static int map_vdso(const struct vdso_image *image, unsigned long addr)
goto up_fail;
}

+ vm_flags = VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|VM_PFNMAP;
+ vm_flags |= MSEAL_SYSTEM_MAPPINGS_VM_FLAG;
vma = _install_special_mapping(mm,
addr + (__VVAR_PAGES - VDSO_NR_VCLOCK_PAGES) * PAGE_SIZE,
VDSO_NR_VCLOCK_PAGES * PAGE_SIZE,
- VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|
- VM_PFNMAP,
+ vm_flags,
&vvar_vclock_mapping);

if (IS_ERR(vma)) {
--
2.48.1.601.g30ceb7b040-goog