From: "Mike Rapoport (IBM)" <rppt@xxxxxxxxxx>
When STRICT_KERNEL_RWX or STRICT_MODULE_RWX is enabled, force text
allocations to use KERNEL_PAGE_ROX.
Signed-off-by: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
---
arch/Kconfig | 3 +++
arch/x86/Kconfig | 1 +
arch/x86/kernel/ftrace.c | 3 ---
arch/x86/mm/init.c | 6 ++++++
include/linux/jitalloc.h | 2 ++
mm/jitalloc.c | 21 +++++++++++++++++++++
6 files changed, 33 insertions(+), 3 deletions(-)
diff --git a/arch/Kconfig b/arch/Kconfig
index 479a7b8be191..e7c4b01307d7 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1307,6 +1307,9 @@ config STRICT_MODULE_RWX
and non-text memory will be made non-executable. This provides
protection against certain security exploits (e.g. writing to text)
+config ARCH_HAS_TEXT_POKE
+ def_bool n
+
# select if the architecture provides an asm/dma-direct.h header
config ARCH_HAS_PHYS_TO_DMA
bool
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index fac4add6ce16..e1a512f557de 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -96,6 +96,7 @@ config X86
select ARCH_HAS_SET_DIRECT_MAP
select ARCH_HAS_STRICT_KERNEL_RWX
select ARCH_HAS_STRICT_MODULE_RWX
+ select ARCH_HAS_TEXT_POKE
select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
select ARCH_HAS_SYSCALL_WRAPPER
select ARCH_HAS_UBSAN_SANITIZE_ALL
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index d50595f2c1a6..bd4dd8974ee6 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -313,7 +313,6 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
unsigned long call_offset;
unsigned long jmp_offset;
unsigned long offset;
- unsigned long npages;
unsigned long size;
unsigned long *ptr;
void *trampoline;
@@ -350,7 +349,6 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
return 0;
*tramp_size = size + RET_SIZE + sizeof(void *);
- npages = DIV_ROUND_UP(*tramp_size, PAGE_SIZE);
/* Copy ftrace_caller onto the trampoline memory */
ret = text_poke_copy(trampoline, (void *)start_offset, size);
@@ -416,7 +414,6 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
/* ALLOC_TRAMP flags lets us know we created it */
ops->flags |= FTRACE_OPS_FL_ALLOC_TRAMP;
- set_memory_rox((unsigned long)trampoline, npages);
return (unsigned long)trampoline;
fail:
tramp_free(trampoline);
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index ffaf9a3840ce..c314738991fa 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -1127,6 +1127,12 @@ struct jit_alloc_params *jit_alloc_arch_params(void)
jit_alloc_params.text.start = MODULES_VADDR + get_jit_load_offset();
jit_alloc_params.text.end = MODULES_END;
+ if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX) ||
+ IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) {
+ jit_alloc_params.text.pgprot = PAGE_KERNEL_ROX;
+ jit_alloc_params.flags |= JIT_ALLOC_USE_TEXT_POKE;
+ }
+
return &jit_alloc_params;
}
#endif /* CONFIG_JIT_ALLOC */
diff --git a/include/linux/jitalloc.h b/include/linux/jitalloc.h
index 0ba5ef785a85..0e29e87acefe 100644
--- a/include/linux/jitalloc.h
+++ b/include/linux/jitalloc.h
@@ -15,9 +15,11 @@
/**
* enum jit_alloc_flags - options for executable memory allocations
* @JIT_ALLOC_KASAN_SHADOW: allocate kasan shadow
+ * @JIT_ALLOC_USE_TEXT_POKE: use text poking APIs to update memory
*/
enum jit_alloc_flags {
JIT_ALLOC_KASAN_SHADOW = (1 << 0),
+ JIT_ALLOC_USE_TEXT_POKE = (1 << 1),
};
/**
diff --git a/mm/jitalloc.c b/mm/jitalloc.c
index a8ae64364d56..15d1067faf3f 100644
--- a/mm/jitalloc.c
+++ b/mm/jitalloc.c
@@ -7,6 +7,26 @@
static struct jit_alloc_params jit_alloc_params;
+#ifdef CONFIG_ARCH_HAS_TEXT_POKE
+#include <asm/text-patching.h>
+
+static inline void jit_text_poke_copy(void *dst, const void *src, size_t len)
+{
+ if (jit_alloc_params.flags & JIT_ALLOC_USE_TEXT_POKE)
+ text_poke_copy(dst, src, len);
+ else
+ memcpy(dst, src, len);
+}
+
+static inline void jit_text_poke_set(void *addr, int c, size_t len)
+{
+ if (jit_alloc_params.flags & JIT_ALLOC_USE_TEXT_POKE)
+ text_poke_set(addr, c, len);
+ else
+ memset(addr, c, len);
+}
+
+#else
static inline void jit_text_poke_copy(void *dst, const void *src, size_t len)
{
memcpy(dst, src, len);
@@ -16,6 +36,7 @@ static inline void jit_text_poke_set(void *addr, int c, size_t len)
{
memset(addr, c, len);
}
+#endif
static void *jit_alloc(size_t len, unsigned int alignment, pgprot_t pgprot,
unsigned long start, unsigned long end,
--
2.35.1
