From 99ac1e2371a562c953af1c276ef7dc373ee263a6 Mon Sep 17 00:00:00 2001 From: David Gow Date: Thu, 26 May 2022 11:54:02 -0700 Subject: arch: um: Fix build for statically linked UML w/ constructors If CONFIG_CONSTUCTORS is enabled on a statically linked (CONFIG_STATIC_LINK=y) build of UML, the build fails due to the .eh_frame section being both used and discarded: ERROR:root:`.eh_frame' referenced in section `.text' of /usr/lib/gcc/x86_64-linux-gnu/11/crtbeginT.o: defined in discarded section `.eh_frame' of /usr/lib/gcc/x86_64-linux-gnu/11/crtbeginT.o `.eh_frame' referenced in section `.text' of /usr/lib/gcc/x86_64-linux-gnu/11/crtbeginT.o: defined in discarded section `.eh_frame' of /usr/lib/gcc/x86_64-linux-gnu/11/crtbeginT.o Instead, keep the .eh_frame section, as we do in dyn.lds.S for dynamically linked UML. This can be reproduced with: ./tools/testing/kunit/kunit.py run --kconfig_add CONFIG_STATIC_LINK=y --kconfig_add CONFIG_GCOV_KERNEL=y --kconfig_add CONFIG_DEBUG_FS=y Signed-off-by: David Gow Signed-off-by: Richard Weinberger --- arch/um/kernel/uml.lds.S | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/um/kernel') diff --git a/arch/um/kernel/uml.lds.S b/arch/um/kernel/uml.lds.S index 7a8e2b123e29..71a59b8adbdc 100644 --- a/arch/um/kernel/uml.lds.S +++ b/arch/um/kernel/uml.lds.S @@ -95,6 +95,7 @@ SECTIONS } .got : { *(.got.plt) *(.got) } + .eh_frame : { KEEP (*(.eh_frame)) } .dynamic : { *(.dynamic) } .tdata : { *(.tdata .tdata.* .gnu.linkonce.td.*) } .tbss : { *(.tbss .tbss.* .gnu.linkonce.tb.*) *(.tcommon) } -- cgit v1.2.3-59-g8ed1b From 5b301409e8bc5d7fad2ee138be44c5c529dd0874 Mon Sep 17 00:00:00 2001 From: Patricia Alfonso Date: Fri, 1 Jul 2022 17:16:20 +0800 Subject: UML: add support for KASAN under x86_64 Make KASAN run on User Mode Linux on x86_64. The UML-specific KASAN initializer uses mmap to map the ~16TB of shadow memory to the location defined by KASAN_SHADOW_OFFSET. kasan_init() utilizes constructors to initialize KASAN before main(). The location of the KASAN shadow memory, starting at KASAN_SHADOW_OFFSET, can be configured using the KASAN_SHADOW_OFFSET option. The default location of this offset is 0x100000000000, which keeps it out-of-the-way even on UML setups with more "physical" memory. For low-memory setups, 0x7fff8000 can be used instead, which fits in an immediate and is therefore faster, as suggested by Dmitry Vyukov. There is usually enough free space at this location; however, it is a config option so that it can be easily changed if needed. Note that, unlike KASAN on other architectures, vmalloc allocations still use the shadow memory allocated upfront, rather than allocating and free-ing it per-vmalloc allocation. If another architecture chooses to go down the same path, we should replace the checks for CONFIG_UML with something more generic, such as: - A CONFIG_KASAN_NO_SHADOW_ALLOC option, which architectures could set - or, a way of having architecture-specific versions of these vmalloc and module shadow memory allocation options. Also note that, while UML supports both KASAN in inline mode (CONFIG_KASAN_INLINE) and static linking (CONFIG_STATIC_LINK), it does not support both at the same time. Signed-off-by: Patricia Alfonso Co-developed-by: Vincent Whitchurch Signed-off-by: Vincent Whitchurch Signed-off-by: David Gow Reviewed-by: Johannes Berg Reviewed-by: Dmitry Vyukov Reviewed-by: Andrey Konovalov Signed-off-by: Richard Weinberger --- arch/um/Kconfig | 15 +++++++++++++++ arch/um/include/asm/common.lds.S | 2 ++ arch/um/include/asm/kasan.h | 37 +++++++++++++++++++++++++++++++++++++ arch/um/kernel/dyn.lds.S | 6 +++++- arch/um/kernel/mem.c | 19 +++++++++++++++++++ arch/um/kernel/stacktrace.c | 2 +- arch/um/os-Linux/mem.c | 22 ++++++++++++++++++++++ arch/um/os-Linux/user_syms.c | 4 ++-- arch/x86/um/Makefile | 3 ++- arch/x86/um/vdso/Makefile | 3 +++ mm/kasan/shadow.c | 29 +++++++++++++++++++++++++++-- 11 files changed, 135 insertions(+), 7 deletions(-) create mode 100644 arch/um/include/asm/kasan.h (limited to 'arch/um/kernel') diff --git a/arch/um/Kconfig b/arch/um/Kconfig index 7b0f953e7d6c..78de31ac1da7 100644 --- a/arch/um/Kconfig +++ b/arch/um/Kconfig @@ -12,6 +12,8 @@ config UML select ARCH_HAS_STRNLEN_USER select ARCH_NO_PREEMPT select HAVE_ARCH_AUDITSYSCALL + select HAVE_ARCH_KASAN if X86_64 + select HAVE_ARCH_KASAN_VMALLOC if HAVE_ARCH_KASAN select HAVE_ARCH_SECCOMP_FILTER select HAVE_ASM_MODVERSIONS select HAVE_UID16 @@ -219,6 +221,19 @@ config UML_TIME_TRAVEL_SUPPORT It is safe to say Y, but you probably don't need this. +config KASAN_SHADOW_OFFSET + hex + depends on KASAN + default 0x100000000000 + help + This is the offset at which the ~16TB of shadow memory is + mapped and used by KASAN for memory debugging. This can be any + address that has at least KASAN_SHADOW_SIZE (total address space divided + by 8) amount of space so that the KASAN shadow memory does not conflict + with anything. The default is 0x100000000000, which works even if mem is + set to a large value. On low-memory systems, try 0x7fff8000, as it fits + into the immediate of most instructions, improving performance. + endmenu source "arch/um/drivers/Kconfig" diff --git a/arch/um/include/asm/common.lds.S b/arch/um/include/asm/common.lds.S index eca6c452a41b..fd481ac371de 100644 --- a/arch/um/include/asm/common.lds.S +++ b/arch/um/include/asm/common.lds.S @@ -83,6 +83,8 @@ } .init_array : { __init_array_start = .; + *(.kasan_init) + *(.init_array.*) *(.init_array) __init_array_end = .; } diff --git a/arch/um/include/asm/kasan.h b/arch/um/include/asm/kasan.h new file mode 100644 index 000000000000..0d6547f4ec85 --- /dev/null +++ b/arch/um/include/asm/kasan.h @@ -0,0 +1,37 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_UM_KASAN_H +#define __ASM_UM_KASAN_H + +#include +#include + +#define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL) + +/* used in kasan_mem_to_shadow to divide by 8 */ +#define KASAN_SHADOW_SCALE_SHIFT 3 + +#ifdef CONFIG_X86_64 +#define KASAN_HOST_USER_SPACE_END_ADDR 0x00007fffffffffffUL +/* KASAN_SHADOW_SIZE is the size of total address space divided by 8 */ +#define KASAN_SHADOW_SIZE ((KASAN_HOST_USER_SPACE_END_ADDR + 1) >> \ + KASAN_SHADOW_SCALE_SHIFT) +#else +#error "KASAN_SHADOW_SIZE is not defined for this sub-architecture" +#endif /* CONFIG_X86_64 */ + +#define KASAN_SHADOW_START (KASAN_SHADOW_OFFSET) +#define KASAN_SHADOW_END (KASAN_SHADOW_START + KASAN_SHADOW_SIZE) + +#ifdef CONFIG_KASAN +void kasan_init(void); +void kasan_map_memory(void *start, unsigned long len); +extern int kasan_um_is_ready; + +#ifdef CONFIG_STATIC_LINK +#define kasan_arch_is_ready() (kasan_um_is_ready) +#endif +#else +static inline void kasan_init(void) { } +#endif /* CONFIG_KASAN */ + +#endif /* __ASM_UM_KASAN_H */ diff --git a/arch/um/kernel/dyn.lds.S b/arch/um/kernel/dyn.lds.S index 2f2a8ce92f1e..2b7fc5b54164 100644 --- a/arch/um/kernel/dyn.lds.S +++ b/arch/um/kernel/dyn.lds.S @@ -109,7 +109,11 @@ SECTIONS be empty, which isn't pretty. */ . = ALIGN(32 / 8); .preinit_array : { *(.preinit_array) } - .init_array : { *(.init_array) } + .init_array : { + *(.kasan_init) + *(.init_array.*) + *(.init_array) + } .fini_array : { *(.fini_array) } .data : { INIT_TASK_DATA(KERNEL_STACK_SIZE) diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c index 15295c3237a0..276a1f0b91f1 100644 --- a/arch/um/kernel/mem.c +++ b/arch/um/kernel/mem.c @@ -18,6 +18,25 @@ #include #include #include +#include + +#ifdef CONFIG_KASAN +int kasan_um_is_ready; +void kasan_init(void) +{ + /* + * kasan_map_memory will map all of the required address space and + * the host machine will allocate physical memory as necessary. + */ + kasan_map_memory((void *)KASAN_SHADOW_START, KASAN_SHADOW_SIZE); + init_task.kasan_depth = 0; + kasan_um_is_ready = true; +} + +static void (*kasan_init_ptr)(void) +__section(".kasan_init") __used += kasan_init; +#endif /* allocated in paging_init, zeroed in mem_init, and unchanged thereafter */ unsigned long *empty_zero_page = NULL; diff --git a/arch/um/kernel/stacktrace.c b/arch/um/kernel/stacktrace.c index 86df52168bd9..fd3b61b3d4d2 100644 --- a/arch/um/kernel/stacktrace.c +++ b/arch/um/kernel/stacktrace.c @@ -27,7 +27,7 @@ void dump_trace(struct task_struct *tsk, frame = (struct stack_frame *)bp; while (((long) sp & (THREAD_SIZE-1)) != 0) { - addr = *sp; + addr = READ_ONCE_NOCHECK(*sp); if (__kernel_text_address(addr)) { reliable = 0; if ((unsigned long) sp == bp + sizeof(long)) { diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c index 3c1b77474d2d..8530b2e08604 100644 --- a/arch/um/os-Linux/mem.c +++ b/arch/um/os-Linux/mem.c @@ -17,6 +17,28 @@ #include #include +/* + * kasan_map_memory - maps memory from @start with a size of @len. + * The allocated memory is filled with zeroes upon success. + * @start: the start address of the memory to be mapped + * @len: the length of the memory to be mapped + * + * This function is used to map shadow memory for KASAN in uml + */ +void kasan_map_memory(void *start, size_t len) +{ + if (mmap(start, + len, + PROT_READ|PROT_WRITE, + MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE|MAP_NORESERVE, + -1, + 0) == MAP_FAILED) { + os_info("Couldn't allocate shadow memory: %s\n.", + strerror(errno)); + exit(1); + } +} + /* Set by make_tempfile() during early boot. */ static char *tempdir = NULL; diff --git a/arch/um/os-Linux/user_syms.c b/arch/um/os-Linux/user_syms.c index 715594fe5719..cb667c9225ab 100644 --- a/arch/um/os-Linux/user_syms.c +++ b/arch/um/os-Linux/user_syms.c @@ -27,10 +27,10 @@ EXPORT_SYMBOL(strstr); #ifndef __x86_64__ extern void *memcpy(void *, const void *, size_t); EXPORT_SYMBOL(memcpy); -#endif - EXPORT_SYMBOL(memmove); EXPORT_SYMBOL(memset); +#endif + EXPORT_SYMBOL(printf); /* Here, instead, I can provide a fake prototype. Yes, someone cares: genksyms. diff --git a/arch/x86/um/Makefile b/arch/x86/um/Makefile index ba5789c35809..f778e37494ba 100644 --- a/arch/x86/um/Makefile +++ b/arch/x86/um/Makefile @@ -28,7 +28,8 @@ else obj-y += syscalls_64.o vdso/ -subarch-y = ../lib/csum-partial_64.o ../lib/memcpy_64.o ../entry/thunk_64.o +subarch-y = ../lib/csum-partial_64.o ../lib/memcpy_64.o ../entry/thunk_64.o \ + ../lib/memmove_64.o ../lib/memset_64.o endif diff --git a/arch/x86/um/vdso/Makefile b/arch/x86/um/vdso/Makefile index 5943387e3f35..8c0396fd0e6f 100644 --- a/arch/x86/um/vdso/Makefile +++ b/arch/x86/um/vdso/Makefile @@ -3,6 +3,9 @@ # Building vDSO images for x86. # +# do not instrument on vdso because KASAN is not compatible with user mode +KASAN_SANITIZE := n + # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in. KCOV_INSTRUMENT := n diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c index a4f07de21771..0e3648b603a6 100644 --- a/mm/kasan/shadow.c +++ b/mm/kasan/shadow.c @@ -295,9 +295,22 @@ int kasan_populate_vmalloc(unsigned long addr, unsigned long size) return 0; shadow_start = (unsigned long)kasan_mem_to_shadow((void *)addr); - shadow_start = ALIGN_DOWN(shadow_start, PAGE_SIZE); shadow_end = (unsigned long)kasan_mem_to_shadow((void *)addr + size); - shadow_end = ALIGN(shadow_end, PAGE_SIZE); + + /* + * User Mode Linux maps enough shadow memory for all of virtual memory + * at boot, so doesn't need to allocate more on vmalloc, just clear it. + * + * The remaining CONFIG_UML checks in this file exist for the same + * reason. + */ + if (IS_ENABLED(CONFIG_UML)) { + __memset((void *)shadow_start, KASAN_VMALLOC_INVALID, shadow_end - shadow_start); + return 0; + } + + shadow_start = PAGE_ALIGN_DOWN(shadow_start); + shadow_end = PAGE_ALIGN(shadow_end); ret = apply_to_page_range(&init_mm, shadow_start, shadow_end - shadow_start, @@ -466,6 +479,10 @@ void kasan_release_vmalloc(unsigned long start, unsigned long end, if (shadow_end > shadow_start) { size = shadow_end - shadow_start; + if (IS_ENABLED(CONFIG_UML)) { + __memset(shadow_start, KASAN_SHADOW_INIT, shadow_end - shadow_start); + return; + } apply_to_existing_page_range(&init_mm, (unsigned long)shadow_start, size, kasan_depopulate_vmalloc_pte, @@ -531,6 +548,11 @@ int kasan_alloc_module_shadow(void *addr, size_t size, gfp_t gfp_mask) if (WARN_ON(!PAGE_ALIGNED(shadow_start))) return -EINVAL; + if (IS_ENABLED(CONFIG_UML)) { + __memset((void *)shadow_start, KASAN_SHADOW_INIT, shadow_size); + return 0; + } + ret = __vmalloc_node_range(shadow_size, 1, shadow_start, shadow_start + shadow_size, GFP_KERNEL, @@ -554,6 +576,9 @@ int kasan_alloc_module_shadow(void *addr, size_t size, gfp_t gfp_mask) void kasan_free_module_shadow(const struct vm_struct *vm) { + if (IS_ENABLED(CONFIG_UML)) + return; + if (vm->flags & VM_KASAN) vfree(kasan_mem_to_shadow(vm->addr)); } -- cgit v1.2.3-59-g8ed1b From 637285e7f8d6da70a70c64e7895cb0672357a1f7 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 14 Jul 2022 12:20:19 +0200 Subject: um: Add missing apply_returns() Implement apply_returns() stub for UM, just like all the other patching routines. Fixes: 15e67227c49a ("x86: Undo return-thunk damage") Reported-by: Randy Dunlap Signed-off-by: Richard Weinberger --- arch/um/kernel/um_arch.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/um/kernel') diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c index 0760e24f2eba..9838967d0b2f 100644 --- a/arch/um/kernel/um_arch.c +++ b/arch/um/kernel/um_arch.c @@ -432,6 +432,10 @@ void apply_retpolines(s32 *start, s32 *end) { } +void apply_returns(s32 *start, s32 *end) +{ +} + void apply_alternatives(struct alt_instr *start, struct alt_instr *end) { } -- cgit v1.2.3-59-g8ed1b