summaryrefslogtreecommitdiff
path: root/arch
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2018-04-29 09:36:22 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-29 09:36:22 -0700
commit65f4d6d0f80b3c55830ec5735194703fa2909ba1 (patch)
tree1a7ea2b9ccad8a38364e888bb927564329059e0e /arch
parent810fb07a9b504ac22b95899cf8b39d25a5f3e5c5 (diff)
parent8bb2610bc4967f19672444a7b0407367f1540028 (diff)
Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 pti fixes from Thomas Gleixner: "A set of updates for the x86/pti related code: - Preserve r8-r11 in int $0x80. r8-r11 need to be preserved, but the int$80 entry code removed that quite some time ago. Make it correct again. - A set of fixes for the Global Bit work which went into 4.17 and caused a bunch of interesting regressions: - Triggering a BUG in the page attribute code due to a missing check for early boot stage - Warnings in the page attribute code about holes in the kernel text mapping which are caused by the freeing of the init code. Handle such holes gracefully. - Reduce the amount of kernel memory which is set global to the actual text and do not incidentally overlap with data. - Disable the global bit when RANDSTRUCT is enabled as it partially defeats the hardening. - Make the page protection setup correct for vma->page_prot population again. The adjustment of the protections fell through the crack during the Global bit rework and triggers warnings on machines which do not support certain features, e.g. NX" * 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/entry/64/compat: Preserve r8-r11 in int $0x80 x86/pti: Filter at vma->vm_page_prot population x86/pti: Disallow global kernel text with RANDSTRUCT x86/pti: Reduce amount of kernel text allowed to be Global x86/pti: Fix boot warning from Global-bit setting x86/pti: Fix boot problems from Global-bit setting
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/Kconfig4
-rw-r--r--arch/x86/entry/entry_64_compat.S8
-rw-r--r--arch/x86/include/asm/pgtable.h5
-rw-r--r--arch/x86/mm/pageattr.c44
-rw-r--r--arch/x86/mm/pti.c26
5 files changed, 68 insertions, 19 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 00fcf81f2c56..c07f492b871a 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -52,6 +52,7 @@ config X86
select ARCH_HAS_DEVMEM_IS_ALLOWED
select ARCH_HAS_ELF_RANDOMIZE
select ARCH_HAS_FAST_MULTIPLIER
+ select ARCH_HAS_FILTER_PGPROT
select ARCH_HAS_FORTIFY_SOURCE
select ARCH_HAS_GCOV_PROFILE_ALL
select ARCH_HAS_KCOV if X86_64
@@ -273,6 +274,9 @@ config ARCH_HAS_CPU_RELAX
config ARCH_HAS_CACHE_LINE_SIZE
def_bool y
+config ARCH_HAS_FILTER_PGPROT
+ def_bool y
+
config HAVE_SETUP_PER_CPU_AREA
def_bool y
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index 9af927e59d49..9de7f1e1dede 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -84,13 +84,13 @@ ENTRY(entry_SYSENTER_compat)
pushq %rdx /* pt_regs->dx */
pushq %rcx /* pt_regs->cx */
pushq $-ENOSYS /* pt_regs->ax */
- pushq $0 /* pt_regs->r8 = 0 */
+ pushq %r8 /* pt_regs->r8 */
xorl %r8d, %r8d /* nospec r8 */
- pushq $0 /* pt_regs->r9 = 0 */
+ pushq %r9 /* pt_regs->r9 */
xorl %r9d, %r9d /* nospec r9 */
- pushq $0 /* pt_regs->r10 = 0 */
+ pushq %r10 /* pt_regs->r10 */
xorl %r10d, %r10d /* nospec r10 */
- pushq $0 /* pt_regs->r11 = 0 */
+ pushq %r11 /* pt_regs->r11 */
xorl %r11d, %r11d /* nospec r11 */
pushq %rbx /* pt_regs->rbx */
xorl %ebx, %ebx /* nospec rbx */
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 5f49b4ff0c24..f1633de5a675 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -601,6 +601,11 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
#define canon_pgprot(p) __pgprot(massage_pgprot(p))
+static inline pgprot_t arch_filter_pgprot(pgprot_t prot)
+{
+ return canon_pgprot(prot);
+}
+
static inline int is_new_memtype_allowed(u64 paddr, unsigned long size,
enum page_cache_mode pcm,
enum page_cache_mode new_pcm)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 0f3d50f4c48c..3bded76e8d5c 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -93,6 +93,18 @@ void arch_report_meminfo(struct seq_file *m)
static inline void split_page_count(int level) { }
#endif
+static inline int
+within(unsigned long addr, unsigned long start, unsigned long end)
+{
+ return addr >= start && addr < end;
+}
+
+static inline int
+within_inclusive(unsigned long addr, unsigned long start, unsigned long end)
+{
+ return addr >= start && addr <= end;
+}
+
#ifdef CONFIG_X86_64
static inline unsigned long highmap_start_pfn(void)
@@ -106,20 +118,25 @@ static inline unsigned long highmap_end_pfn(void)
return __pa_symbol(roundup(_brk_end, PMD_SIZE) - 1) >> PAGE_SHIFT;
}
-#endif
-
-static inline int
-within(unsigned long addr, unsigned long start, unsigned long end)
+static bool __cpa_pfn_in_highmap(unsigned long pfn)
{
- return addr >= start && addr < end;
+ /*
+ * Kernel text has an alias mapping at a high address, known
+ * here as "highmap".
+ */
+ return within_inclusive(pfn, highmap_start_pfn(), highmap_end_pfn());
}
-static inline int
-within_inclusive(unsigned long addr, unsigned long start, unsigned long end)
+#else
+
+static bool __cpa_pfn_in_highmap(unsigned long pfn)
{
- return addr >= start && addr <= end;
+ /* There is no highmap on 32-bit */
+ return false;
}
+#endif
+
/*
* Flushing functions
*/
@@ -172,7 +189,7 @@ static void __cpa_flush_all(void *arg)
static void cpa_flush_all(unsigned long cache)
{
- BUG_ON(irqs_disabled());
+ BUG_ON(irqs_disabled() && !early_boot_irqs_disabled);
on_each_cpu(__cpa_flush_all, (void *) cache, 1);
}
@@ -236,7 +253,7 @@ static void cpa_flush_array(unsigned long *start, int numpages, int cache,
unsigned long do_wbinvd = cache && numpages >= 1024; /* 4M threshold */
#endif
- BUG_ON(irqs_disabled());
+ BUG_ON(irqs_disabled() && !early_boot_irqs_disabled);
on_each_cpu(__cpa_flush_all, (void *) do_wbinvd, 1);
@@ -1183,6 +1200,10 @@ static int __cpa_process_fault(struct cpa_data *cpa, unsigned long vaddr,
cpa->numpages = 1;
cpa->pfn = __pa(vaddr) >> PAGE_SHIFT;
return 0;
+
+ } else if (__cpa_pfn_in_highmap(cpa->pfn)) {
+ /* Faults in the highmap are OK, so do not warn: */
+ return -EFAULT;
} else {
WARN(1, KERN_WARNING "CPA: called for zero pte. "
"vaddr = %lx cpa->vaddr = %lx\n", vaddr,
@@ -1335,8 +1356,7 @@ static int cpa_process_alias(struct cpa_data *cpa)
* to touch the high mapped kernel as well:
*/
if (!within(vaddr, (unsigned long)_text, _brk_end) &&
- within_inclusive(cpa->pfn, highmap_start_pfn(),
- highmap_end_pfn())) {
+ __cpa_pfn_in_highmap(cpa->pfn)) {
unsigned long temp_cpa_vaddr = (cpa->pfn << PAGE_SHIFT) +
__START_KERNEL_map - phys_base;
alias_cpa = *cpa;
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index f1fd52f449e0..4d418e705878 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -421,6 +421,16 @@ static inline bool pti_kernel_image_global_ok(void)
if (boot_cpu_has(X86_FEATURE_K8))
return false;
+ /*
+ * RANDSTRUCT derives its hardening benefits from the
+ * attacker's lack of knowledge about the layout of kernel
+ * data structures. Keep the kernel image non-global in
+ * cases where RANDSTRUCT is in use to help keep the layout a
+ * secret.
+ */
+ if (IS_ENABLED(CONFIG_GCC_PLUGIN_RANDSTRUCT))
+ return false;
+
return true;
}
@@ -430,12 +440,24 @@ static inline bool pti_kernel_image_global_ok(void)
*/
void pti_clone_kernel_text(void)
{
+ /*
+ * rodata is part of the kernel image and is normally
+ * readable on the filesystem or on the web. But, do not
+ * clone the areas past rodata, they might contain secrets.
+ */
unsigned long start = PFN_ALIGN(_text);
- unsigned long end = ALIGN((unsigned long)_end, PMD_PAGE_SIZE);
+ unsigned long end = (unsigned long)__end_rodata_hpage_align;
if (!pti_kernel_image_global_ok())
return;
+ pr_debug("mapping partial kernel image into user address space\n");
+
+ /*
+ * Note that this will undo _some_ of the work that
+ * pti_set_kernel_image_nonglobal() did to clear the
+ * global bit.
+ */
pti_clone_pmds(start, end, _PAGE_RW);
}
@@ -458,8 +480,6 @@ void pti_set_kernel_image_nonglobal(void)
if (pti_kernel_image_global_ok())
return;
- pr_debug("set kernel image non-global\n");
-
set_memory_nonglobal(start, (end - start) >> PAGE_SHIFT);
}