[PATCH 13/13] x86/jitalloc: make memory allocated for code ROX
From: Mike Rapoport <rppt@kernel.org>
Date: 2023-06-01 10:20:58
Also in:
bpf, linux-arm-kernel, linux-mips, linux-modules, linux-riscv, linux-s390, linux-trace-kernel, linuxppc-dev, lkml, loongarch, sparclinux
Subsystem:
function hooks (ftrace), memory management, the rest, x86 architecture (32-bit and 64-bit), x86 mm · Maintainers:
Steven Rostedt, Masami Hiramatsu, Andrew Morton, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Andy Lutomirski, Peter Zijlstra
From: "Mike Rapoport (IBM)" <rppt@kernel.org> 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@kernel.org> --- 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