diff options
| -rw-r--r-- | arch/Kconfig | 9 | ||||
| -rw-r--r-- | arch/x86/Kconfig | 1 | ||||
| -rw-r--r-- | arch/x86/include/asm/thread_info.h | 44 | ||||
| -rw-r--r-- | include/linux/thread_info.h | 9 |
4 files changed, 63 insertions, 0 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index 15996290fed4..ef86cded5402 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -424,6 +424,15 @@ config CC_STACKPROTECTOR_STRONG endchoice +config HAVE_ARCH_WITHIN_STACK_FRAMES + bool + help + An architecture should select this if it can walk the kernel stack + frames to determine if an object is part of either the arguments + or local variables (i.e. that it excludes saved return addresses, + and similar) by implementing an inline arch_within_stack_frames(), + which is used by CONFIG_HARDENED_USERCOPY. + config HAVE_CONTEXT_TRACKING bool help diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index d9a94da0c29f..a2865ddfc1ff 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -91,6 +91,7 @@ config X86 select HAVE_ARCH_SOFT_DIRTY if X86_64 select HAVE_ARCH_TRACEHOOK select HAVE_ARCH_TRANSPARENT_HUGEPAGE + select HAVE_ARCH_WITHIN_STACK_FRAMES select HAVE_EBPF_JIT if X86_64 select HAVE_CC_STACKPROTECTOR select HAVE_CMPXCHG_DOUBLE diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index 30c133ac05cd..ab386f1336f2 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -180,6 +180,50 @@ static inline unsigned long current_stack_pointer(void) return sp; } +/* + * Walks up the stack frames to make sure that the specified object is + * entirely contained by a single stack frame. + * + * Returns: + * 1 if within a frame + * -1 if placed across a frame boundary (or outside stack) + * 0 unable to determine (no frame pointers, etc) + */ +static inline int arch_within_stack_frames(const void * const stack, + const void * const stackend, + const void *obj, unsigned long len) +{ +#if defined(CONFIG_FRAME_POINTER) + const void *frame = NULL; + const void *oldframe; + + oldframe = __builtin_frame_address(1); + if (oldframe) + frame = __builtin_frame_address(2); + /* + * low ----------------------------------------------> high + * [saved bp][saved ip][args][local vars][saved bp][saved ip] + * ^----------------^ + * allow copies only within here + */ + while (stack <= frame && frame < stackend) { + /* + * If obj + len extends past the last frame, this + * check won't pass and the next frame will be 0, + * causing us to bail out and correctly report + * the copy as invalid. + */ + if (obj + len <= frame) + return obj >= oldframe + 2 * sizeof(void *) ? 1 : -1; + oldframe = frame; + frame = *(const void * const *)frame; + } + return -1; +#else + return 0; +#endif +} + #else /* !__ASSEMBLY__ */ #ifdef CONFIG_X86_64 diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h index b4c2a485b28a..3d5c80b4391d 100644 --- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -146,6 +146,15 @@ static inline bool test_and_clear_restore_sigmask(void) #error "no set_restore_sigmask() provided and default one won't work" #endif +#ifndef CONFIG_HAVE_ARCH_WITHIN_STACK_FRAMES +static inline int arch_within_stack_frames(const void * const stack, + const void * const stackend, + const void *obj, unsigned long len) +{ + return 0; +} +#endif + #endif /* __KERNEL__ */ #endif /* _LINUX_THREAD_INFO_H */ |