diff options
| -rw-r--r-- | arch/Kconfig | 9 | ||||
| -rw-r--r-- | arch/arm/Kconfig | 1 | ||||
| -rw-r--r-- | arch/arm/include/asm/uaccess.h | 11 | ||||
| -rw-r--r-- | arch/arm64/Kconfig | 1 | ||||
| -rw-r--r-- | arch/arm64/include/asm/uaccess.h | 15 | ||||
| -rw-r--r-- | arch/ia64/Kconfig | 1 | ||||
| -rw-r--r-- | arch/ia64/include/asm/uaccess.h | 18 | ||||
| -rw-r--r-- | arch/powerpc/Kconfig | 1 | ||||
| -rw-r--r-- | arch/powerpc/include/asm/uaccess.h | 21 | ||||
| -rw-r--r-- | arch/s390/Kconfig | 1 | ||||
| -rw-r--r-- | arch/s390/lib/uaccess.c | 2 | ||||
| -rw-r--r-- | arch/sparc/Kconfig | 1 | ||||
| -rw-r--r-- | arch/sparc/include/asm/uaccess_32.h | 14 | ||||
| -rw-r--r-- | arch/sparc/include/asm/uaccess_64.h | 11 | ||||
| -rw-r--r-- | arch/x86/Kconfig | 2 | ||||
| -rw-r--r-- | arch/x86/include/asm/thread_info.h | 44 | ||||
| -rw-r--r-- | arch/x86/include/asm/uaccess.h | 10 | ||||
| -rw-r--r-- | arch/x86/include/asm/uaccess_32.h | 2 | ||||
| -rw-r--r-- | arch/x86/include/asm/uaccess_64.h | 2 | ||||
| -rw-r--r-- | include/linux/mmzone.h | 2 | ||||
| -rw-r--r-- | include/linux/slab.h | 12 | ||||
| -rw-r--r-- | include/linux/thread_info.h | 24 | ||||
| -rw-r--r-- | init/Kconfig | 2 | ||||
| -rw-r--r-- | mm/Makefile | 4 | ||||
| -rw-r--r-- | mm/slab.c | 30 | ||||
| -rw-r--r-- | mm/slub.c | 40 | ||||
| -rw-r--r-- | mm/usercopy.c | 268 | ||||
| -rw-r--r-- | security/Kconfig | 28 |
28 files changed, 555 insertions, 22 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index bd8056b5b246..e9c9334507dd 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -461,6 +461,15 @@ 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/arm/Kconfig b/arch/arm/Kconfig index 2d601d769a1c..a9c4e48bb7ec 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -35,6 +35,7 @@ config ARM select HARDIRQS_SW_RESEND select HAVE_ARCH_AUDITSYSCALL if (AEABI && !OABI_COMPAT) select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6 + select HAVE_ARCH_HARDENED_USERCOPY select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU select HAVE_ARCH_KGDB if !CPU_ENDIAN_BE32 && MMU select HAVE_ARCH_MMAP_RND_BITS if MMU diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 62a6f65029e6..a93c0f99acf7 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -480,7 +480,10 @@ arm_copy_from_user(void *to, const void __user *from, unsigned long n); static inline unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n) { - unsigned int __ua_flags = uaccess_save_and_enable(); + unsigned int __ua_flags; + + check_object_size(to, n, false); + __ua_flags = uaccess_save_and_enable(); n = arm_copy_from_user(to, from, n); uaccess_restore(__ua_flags); return n; @@ -495,11 +498,15 @@ static inline unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n) { #ifndef CONFIG_UACCESS_WITH_MEMCPY - unsigned int __ua_flags = uaccess_save_and_enable(); + unsigned int __ua_flags; + + check_object_size(from, n, true); + __ua_flags = uaccess_save_and_enable(); n = arm_copy_to_user(to, from, n); uaccess_restore(__ua_flags); return n; #else + check_object_size(from, n, true); return arm_copy_to_user(to, from, n); #endif } diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 69c8787bec7d..bc3f00f586f1 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -54,6 +54,7 @@ config ARM64 select HAVE_ALIGNED_STRUCT_PAGE if SLUB select HAVE_ARCH_AUDITSYSCALL select HAVE_ARCH_BITREVERSE + select HAVE_ARCH_HARDENED_USERCOPY select HAVE_ARCH_HUGE_VMAP select HAVE_ARCH_JUMP_LABEL select HAVE_ARCH_KASAN if SPARSEMEM_VMEMMAP && !(ARM64_16K_PAGES && ARM64_VA_BITS_48) diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 5e834d10b291..c47257c91b77 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -265,22 +265,25 @@ extern unsigned long __must_check __clear_user(void __user *addr, unsigned long static inline unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n) { kasan_check_write(to, n); - return __arch_copy_from_user(to, from, n); + check_object_size(to, n, false); + return __arch_copy_from_user(to, from, n); } static inline unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n) { kasan_check_read(from, n); - return __arch_copy_to_user(to, from, n); + check_object_size(from, n, true); + return __arch_copy_to_user(to, from, n); } static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n) { kasan_check_write(to, n); - if (access_ok(VERIFY_READ, from, n)) + if (access_ok(VERIFY_READ, from, n)) { + check_object_size(to, n, false); n = __arch_copy_from_user(to, from, n); - else /* security hole - plug it */ + } else /* security hole - plug it */ memset(to, 0, n); return n; } @@ -289,8 +292,10 @@ static inline unsigned long __must_check copy_to_user(void __user *to, const voi { kasan_check_read(from, n); - if (access_ok(VERIFY_WRITE, to, n)) + if (access_ok(VERIFY_WRITE, to, n)) { + check_object_size(from, n, true); n = __arch_copy_to_user(to, from, n); + } return n; } diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig index 6a15083cc366..18ca6a9ce566 100644 --- a/arch/ia64/Kconfig +++ b/arch/ia64/Kconfig @@ -52,6 +52,7 @@ config IA64 select MODULES_USE_ELF_RELA select ARCH_USE_CMPXCHG_LOCKREF select HAVE_ARCH_AUDITSYSCALL + select HAVE_ARCH_HARDENED_USERCOPY default y help The Itanium Processor Family is Intel's 64-bit successor to diff --git a/arch/ia64/include/asm/uaccess.h b/arch/ia64/include/asm/uaccess.h index 2189d5ddc1ee..465c70982f40 100644 --- a/arch/ia64/include/asm/uaccess.h +++ b/arch/ia64/include/asm/uaccess.h @@ -241,12 +241,18 @@ extern unsigned long __must_check __copy_user (void __user *to, const void __use static inline unsigned long __copy_to_user (void __user *to, const void *from, unsigned long count) { + if (!__builtin_constant_p(count)) + check_object_size(from, count, true); + return __copy_user(to, (__force void __user *) from, count); } static inline unsigned long __copy_from_user (void *to, const void __user *from, unsigned long count) { + if (!__builtin_constant_p(count)) + check_object_size(to, count, false); + return __copy_user((__force void __user *) to, from, count); } @@ -258,8 +264,11 @@ __copy_from_user (void *to, const void __user *from, unsigned long count) const void *__cu_from = (from); \ long __cu_len = (n); \ \ - if (__access_ok(__cu_to, __cu_len, get_fs())) \ - __cu_len = __copy_user(__cu_to, (__force void __user *) __cu_from, __cu_len); \ + if (__access_ok(__cu_to, __cu_len, get_fs())) { \ + if (!__builtin_constant_p(n)) \ + check_object_size(__cu_from, __cu_len, true); \ + __cu_len = __copy_user(__cu_to, (__force void __user *) __cu_from, __cu_len); \ + } \ __cu_len; \ }) @@ -270,8 +279,11 @@ __copy_from_user (void *to, const void __user *from, unsigned long count) long __cu_len = (n); \ \ __chk_user_ptr(__cu_from); \ - if (__access_ok(__cu_from, __cu_len, get_fs())) \ + if (__access_ok(__cu_from, __cu_len, get_fs())) { \ + if (!__builtin_constant_p(n)) \ + check_object_size(__cu_to, __cu_len, false); \ __cu_len = __copy_user((__force void __user *) __cu_to, __cu_from, __cu_len); \ + } \ __cu_len; \ }) diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index ec4047e170a0..927d2ab2ce08 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -166,6 +166,7 @@ config PPC select HAVE_LIVEPATCH if HAVE_DYNAMIC_FTRACE_WITH_REGS select GENERIC_CPU_AUTOPROBE select HAVE_VIRT_CPU_ACCOUNTING + select HAVE_ARCH_HARDENED_USERCOPY config GENERIC_CSUM def_bool CPU_LITTLE_ENDIAN diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h index b7c20f0b8fbe..c1dc6c14deb8 100644 --- a/arch/powerpc/include/asm/uaccess.h +++ b/arch/powerpc/include/asm/uaccess.h @@ -310,10 +310,15 @@ static inline unsigned long copy_from_user(void *to, { unsigned long over; - if (access_ok(VERIFY_READ, from, n)) + if (access_ok(VERIFY_READ, from, n)) { + if (!__builtin_constant_p(n)) + check_object_size(to, n, false); return __copy_tofrom_user((__force void __user *)to, from, n); + } if ((unsigned long)from < TASK_SIZE) { over = (unsigned long)from + n - TASK_SIZE; + if (!__builtin_constant_p(n - over)) + check_object_size(to, n - over, false); return __copy_tofrom_user((__force void __user *)to, from, n - over) + over; } @@ -325,10 +330,15 @@ static inline unsigned long copy_to_user(void __user *to, { unsigned long over; - if (access_ok(VERIFY_WRITE, to, n)) + if (access_ok(VERIFY_WRITE, to, n)) { + if (!__builtin_constant_p(n)) + check_object_size(from, n, true); return __copy_tofrom_user(to, (__force void __user *)from, n); + } if ((unsigned long)to < TASK_SIZE) { over = (unsigned long)to + n - TASK_SIZE; + if (!__builtin_constant_p(n)) + check_object_size(from, n - over, true); return __copy_tofrom_user(to, (__force void __user *)from, n - over) + over; } @@ -372,6 +382,10 @@ static inline unsigned long __copy_from_user_inatomic(void *to, if (ret == 0) return 0; } + + if (!__builtin_constant_p(n)) + check_object_size(to, n, false); + return __copy_tofrom_user((__force void __user *)to, from, n); } @@ -398,6 +412,9 @@ static inline unsigned long __copy_to_user_inatomic(void __user *to, if (ret == 0) return 0; } + if (!__builtin_constant_p(n)) + check_object_size(from, n, true); + return __copy_tofrom_user(to, (__force const void __user *)from, n); } diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 9e607bf2d640..0e348781327b 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -123,6 +123,7 @@ config S390 select HAVE_ALIGNED_STRUCT_PAGE if SLUB select HAVE_ARCH_AUDITSYSCALL select HAVE_ARCH_EARLY_PFN_TO_NID + select HAVE_ARCH_HARDENED_USERCOPY select HAVE_ARCH_JUMP_LABEL select CPU_NO_EFFICIENT_FFS if !HAVE_MARCH_Z9_109_FEATURES select HAVE_ARCH_SECCOMP_FILTER diff --git a/arch/s390/lib/uaccess.c b/arch/s390/lib/uaccess.c index d96596128e9f..f481fcde067b 100644 --- a/arch/s390/lib/uaccess.c +++ b/arch/s390/lib/uaccess.c @@ -104,6 +104,7 @@ static inline unsigned long copy_from_user_mvcp(void *x, const void __user *ptr, unsigned long __copy_from_user(void *to, const void __user *from, unsigned long n) { + check_object_size(to, n, false); if (static_branch_likely(&have_mvcos)) return copy_from_user_mvcos(to, from, n); return copy_from_user_mvcp(to, from, n); @@ -177,6 +178,7 @@ static inline unsigned long copy_to_user_mvcs(void __user *ptr, const void *x, unsigned long __copy_to_user(void __user *to, const void *from, unsigned long n) { + check_object_size(from, n, true); if (static_branch_likely(&have_mvcos)) return copy_to_user_mvcos(to, from, n); return copy_to_user_mvcs(to, from, n); diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig index 546293d9e6c5..59b09600dd32 100644 --- a/arch/sparc/Kconfig +++ b/arch/sparc/Kconfig @@ -43,6 +43,7 @@ config SPARC select OLD_SIGSUSPEND select ARCH_HAS_SG_CHAIN select CPU_NO_EFFICIENT_FFS + select HAVE_ARCH_HARDENED_USERCOPY config SPARC32 def_bool !64BIT diff --git a/arch/sparc/include/asm/uaccess_32.h b/arch/sparc/include/asm/uaccess_32.h index 57aca2792d29..341a5a133f48 100644 --- a/arch/sparc/include/asm/uaccess_32.h +++ b/arch/sparc/include/asm/uaccess_32.h @@ -248,22 +248,28 @@ unsigned long __copy_user(void __user *to, const void __user *from, unsigned lon static inline unsigned long copy_to_user(void __user *to, const void *from, unsigned long n) { - if (n && __access_ok((unsigned long) to, n)) + if (n && __access_ok((unsigned long) to, n)) { + if (!__builtin_constant_p(n)) + check_object_size(from, n, true); return __copy_user(to, (__force void __user *) from, n); - else + } else return n; } static inline unsigned long __copy_to_user(void __user *to, const void *from, unsigned long n) { + if (!__builtin_constant_p(n)) + check_object_size(from, n, true); return __copy_user(to, (__force void __user *) from, n); } static inline unsigned long copy_from_user(void *to, const void __user *from, unsigned long n) { - if (n && __access_ok((unsigned long) from, n)) + if (n && __access_ok((unsigned long) from, n)) { + if (!__builtin_constant_p(n)) + check_object_size(to, n, false); return __copy_user((__force void __user *) to, from, n); - else + } else return n; } diff --git a/arch/sparc/include/asm/uaccess_64.h b/arch/sparc/include/asm/uaccess_64.h index e9a51d64974d..8bda94fab8e8 100644 --- a/arch/sparc/include/asm/uaccess_64.h +++ b/arch/sparc/include/asm/uaccess_64.h @@ -210,8 +210,12 @@ unsigned long copy_from_user_fixup(void *to, const void __user *from, static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long size) { - unsigned long ret = ___copy_from_user(to, from, size); + unsigned long ret; + if (!__builtin_constant_p(size)) + check_object_size(to, size, false); + + ret = ___copy_from_user(to, from, size); if (unlikely(ret)) ret = copy_from_user_fixup(to, from, size); @@ -227,8 +231,11 @@ unsigned long copy_to_user_fixup(void __user *to, const void *from, static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long size) { - unsigned long ret = ___copy_to_user(to, from, size); + unsigned long ret; + if (!__builtin_constant_p(size)) + check_object_size(from, size, true); + ret = ___copy_to_user(to, from, size); if (unlikely(ret)) ret = copy_to_user_fixup(to, from, size); return ret; diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 5c6e7471b732..c580d8c33562 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -80,6 +80,7 @@ config X86 select HAVE_ALIGNED_STRUCT_PAGE if SLUB select HAVE_AOUT if X86_32 select HAVE_ARCH_AUDITSYSCALL + select HAVE_ARCH_HARDENED_USERCOPY select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE select HAVE_ARCH_JUMP_LABEL select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP @@ -91,6 +92,7 @@ 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 84b59846154a..8b7c8d8e0852 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -176,6 +176,50 @@ 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/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 52f230094c51..a0ae610b9280 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -761,9 +761,10 @@ copy_from_user(void *to, const void __user *from, unsigned long n) * case, and do only runtime checking for non-constant sizes. */ - if (likely(sz < 0 || sz >= n)) + if (likely(sz < 0 || sz >= n)) { + check_object_size(to, n, false); n = _copy_from_user(to, from, n); - else if(__builtin_constant_p(n)) + } else if (__builtin_constant_p(n)) copy_from_user_overflow(); else __copy_from_user_overflow(sz, n); @@ -781,9 +782,10 @@ copy_to_user(void __user *to, const void *from, unsigned long n) might_fault(); /* See the comment in copy_from_user() above. */ - if (likely(sz < 0 || sz >= n)) + if (likely(sz < 0 || sz >= n)) { + check_object_size(from, n, true); n = _copy_to_user(to, from, n); - else if(__builtin_constant_p(n)) + } else if (__builtin_constant_p(n)) copy_to_user_overflow(); else __copy_to_user_overflow(sz, n); diff --git a/arch/x86/include/asm/uaccess_32.h b/arch/x86/include/asm/uaccess_32.h index 4b32da24faaf..7d3bdd1ed697 100644 --- a/arch/x86/include/asm/uaccess_32.h +++ b/arch/x86/include/asm/uaccess_32.h @@ -37,6 +37,7 @@ unsigned long __must_check __copy_from_user_ll_nocache_nozero static __always_inline unsigned long __must_check __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n) { + check_object_size(from, n, true); return __copy_to_user_ll(to, from, n); } @@ -95,6 +96,7 @@ static __always_inline unsigned long __copy_from_user(void *to, const void __user *from, unsigned long n) { might_fault(); + check_object_size(to, n, false); if (__builtin_constant_p(n)) { unsigned long ret; diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h index 2eac2aa3e37f..673059a109fe 100644 --- a/arch/x86/include/asm/uaccess_64.h +++ b/arch/x86/include/asm/uaccess_64.h @@ -54,6 +54,7 @@ int __copy_from_user_nocheck(void *dst, const void __user *src, unsigned size) { int ret = 0; + check_object_size(dst, size, false); if (!__builtin_constant_p(size)) return copy_user_generic(dst, (__force void *)src, size); switch (size) { @@ -119,6 +120,7 @@ int __copy_to_user_nocheck(void __user *dst, const void *src, unsigned size) { int ret = 0; + check_object_size(src, size, true); if (!__builtin_constant_p(size)) return copy_user_generic((__force void *)dst, src, size); switch (size) { diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index f2e4e90621ec..d572b78b65e1 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -68,8 +68,10 @@ extern char * const migratetype_names[MIGRATE_TYPES]; #ifdef CONFIG_CMA # define is_migrate_cma(migratetype) unlikely((migratetype) == MIGRATE_CMA) +# define is_migrate_cma_page(_page) (get_pageblock_migratetype(_page) == MIGRATE_CMA) #else # define is_migrate_cma(migratetype) false +# define is_migrate_cma_page(_page) false #endif #define for_each_migratetype_order(order, type) \ diff --git a/include/linux/slab.h b/include/linux/slab.h index 1a4ea551aae5..4293808d8cfb 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -155,6 +155,18 @@ void kfree(const void *); void kzfree(const void *); size_t ksize(const void *); +#ifdef CONFIG_HAVE_HARDENED_USERCOPY_ALLOCATOR +const char *__check_heap_object(const void *ptr, unsigned long n, + struct page *page); +#else +static inline const char *__check_heap_object(const void *ptr, + unsigned long n, + struct page *page) +{ + return NULL; +} +#endif + /* * Some archs want to perform DMA into kmalloc caches and need a guaranteed * alignment larger than the alignment of a 64-bit integer. diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h index 352b1542f5cc..cbd8990e2e77 100644 --- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -105,6 +105,30 @@ static inline int test_ti_thread_flag(struct thread_info *ti, int flag) #define tif_need_resched() test_thread_flag(TIF_NEED_RESCHED) +#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 + +#ifdef CONFIG_HARDENED_USERCOPY +extern void __check_object_size(const void *ptr, unsigned long n, + bool to_user); + +static inline void check_object_size(const void *ptr, unsigned long n, + bool to_user) +{ + __check_object_size(ptr, n, to_user); +} +#else +static inline void check_object_size(const void *ptr, unsigned long n, + bool to_user) +{ } +#endif /* CONFIG_HARDENED_USERCOPY */ + #endif /* __KERNEL__ */ #endif /* _LINUX_THREAD_INFO_H */ diff --git a/init/Kconfig b/init/Kconfig index 69886493ff1e..cac3f096050d 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1761,6 +1761,7 @@ choice config SLAB bool "SLAB" + select HAVE_HARDENED_USERCOPY_ALLOCATOR help The regular slab allocator that is established and known to work well in all environments. It organizes cache hot objects in @@ -1768,6 +1769,7 @@ config SLAB config SLUB bool "SLUB (Unqueued Allocator)" + select HAVE_HARDENED_USERCOPY_ALLOCATOR help SLUB is a slab allocator that minimizes cache line usage instead of managing queues of cached objects (SLAB approach). diff --git a/mm/Makefile b/mm/Makefile index fc059666c760..2ca1faf3fa09 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -21,6 +21,9 @@ KCOV_INSTRUMENT_memcontrol.o := n KCOV_INSTRUMENT_mmzone.o := n KCOV_INSTRUMENT_vmstat.o := n +# Since __builtin_frame_address does work as used, disable the warning. +CFLAGS_usercopy.o += $(call cc-disable-warning, frame-address) + mmu-y := nommu.o mmu-$(CONFIG_MMU) := gup.o highmem.o memory.o mincore.o \ mlock.o mmap.o mprotect.o mremap.o msync.o rmap.o \ @@ -99,3 +102,4 @@ obj-$(CONFIG_USERFAULTFD) += userfaultfd.o obj-$(CONFIG_IDLE_PAGE_TRACKING) += page_idle.o obj-$(CONFIG_FRAME_VECTOR) += frame_vector.o obj-$(CONFIG_DEBUG_PAGE_REF) += debug_page_ref.o +obj-$(CONFIG_HARDENED_USERCOPY) += usercopy.o diff --git a/mm/slab.c b/mm/slab.c index 261147ba156f..b67271024135 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -4441,6 +4441,36 @@ static int __init slab_proc_init(void) module_init(slab_proc_init); #endif +#ifdef CONFIG_HARDENED_USERCOPY +/* + * Rejects objects that are incorrectly sized. + * + * Returns NULL if check passes, otherwise const char * to name of cache + * to indicate an error. + */ +const char *__check_heap_object(const void *ptr, unsigned long n, + struct page *page) +{ + struct kmem_cache *cachep; + unsigned int objnr; + unsigned long offset; + + /* Find and validate object. */ + cachep = page->slab_cache; + objnr = obj_to_index(cachep, page, (void *)ptr); + BUG_ON(objnr >= cachep->num); + + /* Find offset within object. */ + offset = ptr - index_to_obj(cachep, page, objnr) - obj_offset(cachep); + + /* Allow address range falling entirely within object size. */ + if (offset <= cachep->object_size && n <= cachep->object_size - offset) + return NULL; + + return cachep->name; +} +#endif /* CONFIG_HARDENED_USERCOPY */ + /** * ksize - get the actual amount of memory allocated for a given object * @objp: Pointer to the object diff --git a/mm/slub.c b/mm/slub.c index 850737bdfbd8..cead06394e9e 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3764,6 +3764,46 @@ void *__kmalloc_node(size_t size, gfp_t flags, int node) EXPORT_SYMBOL(__kmalloc_node); #endif +#ifdef CONFIG_HARDENED_USERCOPY +/* + * Rejects objects that are incorrectly sized. + * + * Returns NULL if check passes, otherwise const char * to name of cache + * to indicate an error. + */ +const char *__check_heap_object(const void *ptr, unsigned long n, + struct page *page) +{ + struct kmem_cache *s; + unsigned long offset; + size_t object_size; + + /* Find object and usable object size. */ + s = page->slab_cache; + object_size = slab_ksize(s); + + /* Reject impossible pointers. */ + if (ptr < page_address(page)) + return s->name; + + /* Find offset within object. */ + offset = (ptr - page_address(page)) % s->size; + + /* Adjust for redzone and reject if within the redzone. */ + if (kmem_cache_debug(s) && s->flags & SLAB_RED_ZONE) { + if (offset < s->red_left_pad) + return s->name; + offset -= s->red_left_pad; + } + + /* Allow address range falling entirely within object size. */ + if (offset <= object_size && n <= object_size - offset) + return NULL; + + return s->name; +} +#endif /* CONFIG_HARDENED_USERCOPY */ + static size_t __ksize(const void *object) { struct page *page; diff --git a/mm/usercopy.c b/mm/usercopy.c new file mode 100644 index 000000000000..8ebae91a6b55 --- /dev/null +++ b/mm/usercopy.c @@ -0,0 +1,268 @@ +/* + * This implements the various checks for CONFIG_HARDENED_USERCOPY*, + * which are designed to protect kernel memory from needless exposure + * and overwrite under many unintended conditions. This code is based + * on PAX_USERCOPY, which is: + * + * Copyright (C) 2001-2016 PaX Team, Bradley Spengler, Open Source + * Security Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/mm.h> +#include <linux/slab.h> +#include <asm/sections.h> + +enum { + BAD_STACK = -1, + NOT_STACK = 0, + GOOD_FRAME, + GOOD_STACK, +}; + +/* + * Checks if a given pointer and length is contained by the current + * stack frame (if possible). + * + * Returns: + * NOT_STACK: not at all on the stack + * GOOD_FRAME: fully within a valid stack frame + * GOOD_STACK: fully on the stack (when can't do frame-checking) + * BAD_STACK: error condition (invalid stack position or bad stack frame) + */ +static noinline int check_stack_object(const void *obj, unsigned long len) +{ + const void * const stack = task_stack_page(current); + const void * const stackend = stack + THREAD_SIZE; + int ret; + + /* Object is not on the stack at all. */ + if (obj + len <= stack || stackend <= obj) + return NOT_STACK; + + /* + * Reject: object partially overlaps the stack (passing the + * the check above means at least one end is within the stack, + * so if this check fails, the other end is outside the stack). + */ + if (obj < stack || stackend < obj + len) + return BAD_STACK; + + /* Check if object is safely within a valid frame. */ + ret = arch_within_stack_frames(stack, stackend, obj, len); + if (ret) + return ret; + + return GOOD_STACK; +} + +static void report_usercopy(const void *ptr, unsigned long len, + bool to_user, const char *type) +{ + pr_emerg("kernel memory %s attempt detected %s %p (%s) (%lu bytes)\n", + to_user ? "exposure" : "overwrite", + to_user ? "from" : "to", ptr, type ? : "unknown", len); + /* + * For greater effect, it would be nice to do do_group_exit(), + * but BUG() actually hooks all the lock-breaking and per-arch + * Oops code, so that is used here instead. + */ + BUG(); +} + +/* Returns true if any portion of [ptr,ptr+n) over laps with [low,high). */ +static bool overlaps(const void *ptr, unsigned long n, unsigned long low, + unsigned long high) +{ + unsigned long check_low = (uintptr_t)ptr; + unsigned long check_high = check_low + n; + + /* Does not overlap if entirely above or entirely below. */ + if (check_low >= high || check_high < low) + return false; + + return true; +} + +/* Is this address range in the kernel text area? */ +static inline const char *check_kernel_text_object(const void *ptr, + unsigned long n) +{ + unsigned long textlow = (unsigned long)_stext; + unsigned long texthigh = (unsigned long)_etext; + unsigned long textlow_linear, texthigh_linear; + + if (overlaps(ptr, n, textlow, texthigh)) + return "<kernel text>"; + + /* + * Some architectures have virtual memory mappings with a secondary + * mapping of the kernel text, i.e. there is more than one virtual + * kernel address that points to the kernel image. It is usually + * when there is a separate linear physical memory mapping, in that + * __pa() is not just the reverse of __va(). This can be detected + * and checked: + */ + textlow_linear = (unsigned long)__va(__pa(textlow)); + /* No different mapping: we're done. */ + if (textlow_linear == textlow) + return NULL; + + /* Check the secondary mapping... */ + texthigh_linear = (unsigned long)__va(__pa(texthigh)); + if (overlaps(ptr, n, textlow_linear, texthigh_linear)) + return "<linear kernel text>"; + + return NULL; +} + +static inline const char *check_bogus_address(const void *ptr, unsigned long n) +{ + /* Reject if object wraps past end of memory. */ + if (ptr + n < ptr) + return "<wrapped address>"; + + /* Reject if NULL or ZERO-allocation. */ + if (ZERO_OR_NULL_PTR(ptr)) + return "<null>"; + + return NULL; +} + +static inline const char *check_heap_object(const void *ptr, unsigned long n, + bool to_user) +{ + struct page *page, *endpage; + const void *end = ptr + n - 1; + bool is_reserved, is_cma; + + /* + * Some architectures (arm64) return true for virt_addr_valid() on + * vmalloced addresses. Work around this by checking for vmalloc + * first. + */ + if (is_vmalloc_addr(ptr)) + return NULL; + + if (!virt_addr_valid(ptr)) + return NULL; + + page = virt_to_head_page(ptr); + + /* Check slab allocator for flags and size. */ + if (PageSlab(page)) + return __check_heap_object(ptr, n, page); + + /* + * Sometimes the kernel data regions are not marked Reserved (see + * check below). And sometimes [_sdata,_edata) does not cover + * rodata and/or bss, so check each range explicitly. + */ + + /* Allow reads of kernel rodata region (if not marked as Reserved). */ + if (ptr >= (const void *)__start_rodata && + end <= (const void *)__end_rodata) { + if (!to_user) + return "<rodata>"; + return NULL; + } + + /* Allow kernel data region (if not marked as Reserved). */ + if (ptr >= (const void *)_sdata && end <= (const void *)_edata) + return NULL; + + /* Allow kernel bss region (if not marked as Reserved). */ + if (ptr >= (const void *)__bss_start && + end <= (const void *)__bss_stop) + return NULL; + + /* Is the object wholly within one base page? */ + if (likely(((unsigned long)ptr & (unsigned long)PAGE_MASK) == + ((unsigned long)end & (unsigned long)PAGE_MASK))) + return NULL; + + /* Allow if start and end are inside the same compound page. */ + endpage = virt_to_head_page(end); + if (likely(endpage == page)) + return NULL; + + /* + * Reject if range is entirely either Reserved (i.e. special or + * device memory), or CMA. Otherwise, reject since the object spans + * several independently allocated pages. + */ + is_reserved = PageReserved(page); + is_cma = is_migrate_cma_page(page); + if (!is_reserved && !is_cma) + goto reject; + + for (ptr += PAGE_SIZE; ptr <= end; ptr += PAGE_SIZE) { + page = virt_to_head_page(ptr); + if (is_reserved && !PageReserved(page)) + goto reject; + if (is_cma && !is_migrate_cma_page(page)) + goto reject; + } + + return NULL; + +reject: + return "<spans multiple pages>"; +} + +/* + * Validates that the given object is: + * - not bogus address + * - known-safe heap or stack object + * - not in kernel text + */ +void __check_object_size(const void *ptr, unsigned long n, bool to_user) +{ + const char *err; + + /* Skip all tests if size is zero. */ + if (!n) + return; + + /* Check for invalid addresses. */ + err = check_bogus_address(ptr, n); + if (err) + goto report; + + /* Check for bad heap object. */ + err = check_heap_object(ptr, n, to_user); + if (err) + goto report; + + /* Check for bad stack object. */ + switch (check_stack_object(ptr, n)) { + case NOT_STACK: + /* Object is not touching the current process stack. */ + break; + case GOOD_FRAME: + case GOOD_STACK: + /* + * Object is either in the correct frame (when it + * is possible to check) or just generally on the + * process stack (when frame checking not available). + */ + return; + default: + err = "<process stack>"; + goto report; + } + + /* Check for object in kernel to avoid text exposure. */ + err = check_kernel_text_object(ptr, n); + if (!err) + return; + +report: + report_usercopy(ptr, n, to_user, err); +} +EXPORT_SYMBOL(__check_object_size); diff --git a/security/Kconfig b/security/Kconfig index 176758cdfa57..df28f2b6f3e1 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -118,6 +118,34 @@ config LSM_MMAP_MIN_ADDR this low address space will need the permission specific to the systems running LSM. +config HAVE_HARDENED_USERCOPY_ALLOCATOR + bool + help + The heap allocator implements __check_heap_object() for + validating memory ranges against heap object sizes in + support of CONFIG_HARDENED_USERCOPY. + +config HAVE_ARCH_HARDENED_USERCOPY + bool + help + The architecture supports CONFIG_HARDENED_USERCOPY by + calling check_object_size() just before performing the + userspace copies in the low level implementation of + copy_to_user() and copy_from_user(). + +config HARDENED_USERCOPY + bool "Harden memory copies between kernel and userspace" + depends on HAVE_ARCH_HARDENED_USERCOPY + select BUG + help + This option checks for obviously wrong memory regions when + copying memory to/from the kernel (via copy_to_user() and + copy_from_user() functions) by rejecting memory ranges that + are larger than the specified heap object, span multiple + separately allocates pages, are not on the process stack, + or are part of the kernel text. This kills entire classes + of heap overflow exploits and similar kernel memory exposures. + source security/selinux/Kconfig source security/smack/Kconfig source security/tomoyo/Kconfig |