guard metadata with Memory Protection Keys (MPK)
This commit is contained in:
parent
ac8c68de53
commit
0b963078d5
5
Makefile
5
Makefile
@ -1,5 +1,6 @@
|
||||
CONFIG_CXX_ALLOCATOR := true
|
||||
CONFIG_UBSAN := false
|
||||
CONFIG_SEAL_METADATA := false
|
||||
|
||||
CPPFLAGS := -D_GNU_SOURCE
|
||||
SHARED_FLAGS := -O2 -flto -fPIC -fvisibility=hidden -fno-plt -pipe -Wall -Wextra -Wcast-align=strict -Wcast-qual -Wwrite-strings
|
||||
@ -22,6 +23,10 @@ ifeq ($(CONFIG_UBSAN),true)
|
||||
CXXFLAGS += -fsanitize=undefined
|
||||
endif
|
||||
|
||||
ifeq ($(CONFIG_SEAL_METADATA),true)
|
||||
CPPFLAGS += -DCONFIG_SEAL_METADATA
|
||||
endif
|
||||
|
||||
hardened_malloc.so: $(OBJECTS)
|
||||
$(CC) $(CFLAGS) $(LDFLAGS) -shared $^ $(LDLIBS) -o $@
|
||||
|
||||
|
@ -64,6 +64,10 @@ The available configuration options are the following:
|
||||
C++ allocator is replaced for slightly improved performance and detection of
|
||||
mismatched sizes for sized deallocation (often type confusion bugs). This
|
||||
will result in linking against the C++ standard library.
|
||||
* `CONFIG_SEAL_METADATA`: `true` or `false` (default) to control whether Memory
|
||||
Protection Keys are used to disable access to all writable allocator state
|
||||
outside of the memory allocator code. It's currently disabled by default due
|
||||
to being extremely experimental and needing some minor optimization work.
|
||||
|
||||
Compile-time configuration is available in the `config.h` file for controlling
|
||||
the balance between security and performance / memory usage. By default, all
|
||||
@ -190,7 +194,7 @@ was a bit less important and if a core goal was finding latent bugs.
|
||||
the library doesn't leak the address of writable state
|
||||
* Allocator state is located within a dedicated region with high entropy
|
||||
randomly sized guard regions around it
|
||||
* [in-progress] Protection via Memory Protection Keys (MPK) on x86\_64
|
||||
* Protection via Memory Protection Keys (MPK) on x86\_64
|
||||
* [future] Protection via MTE on ARMv8.5+
|
||||
* Extension for retrieving the size of allocations with fallback
|
||||
to a sentinel for pointers not managed by the allocator
|
||||
|
102
malloc.c
102
malloc.c
@ -6,6 +6,7 @@
|
||||
#include <string.h>
|
||||
|
||||
#include <pthread.h>
|
||||
#include <sys/mman.h>
|
||||
#include <unistd.h>
|
||||
|
||||
#include "third_party/libdivide.h"
|
||||
@ -43,6 +44,9 @@ static union {
|
||||
struct size_class *size_class_metadata;
|
||||
struct region_allocator *region_allocator;
|
||||
struct region_metadata *regions[2];
|
||||
#ifdef USE_PKEY
|
||||
int metadata_pkey;
|
||||
#endif
|
||||
atomic_bool initialized;
|
||||
};
|
||||
char padding[PAGE_SIZE];
|
||||
@ -82,6 +86,26 @@ static const u16 size_class_slots[] = {
|
||||
/* 2048 */ 6, 5, 4, 4
|
||||
};
|
||||
|
||||
int get_metadata_key(void) {
|
||||
#ifdef USE_PKEY
|
||||
return ro.metadata_pkey;
|
||||
#else
|
||||
return -1;
|
||||
#endif
|
||||
}
|
||||
|
||||
static inline void thread_unseal_metadata(void) {
|
||||
#ifdef USE_PKEY
|
||||
pkey_set(ro.metadata_pkey, 0);
|
||||
#endif
|
||||
}
|
||||
|
||||
static inline void thread_seal_metadata(void) {
|
||||
#ifdef USE_PKEY
|
||||
pkey_set(ro.metadata_pkey, PKEY_DISABLE_ACCESS);
|
||||
#endif
|
||||
}
|
||||
|
||||
#define N_SIZE_CLASSES (sizeof(size_classes) / sizeof(size_classes[0]))
|
||||
|
||||
struct size_info {
|
||||
@ -182,7 +206,7 @@ static struct slab_metadata *alloc_metadata(struct size_class *c, size_t slab_si
|
||||
if (allocate > metadata_max) {
|
||||
allocate = metadata_max;
|
||||
}
|
||||
if (memory_protect_rw(c->slab_info, allocate * sizeof(struct slab_metadata))) {
|
||||
if (memory_protect_rw_metadata(c->slab_info, allocate * sizeof(struct slab_metadata))) {
|
||||
return NULL;
|
||||
}
|
||||
c->metadata_allocated = allocate;
|
||||
@ -638,7 +662,7 @@ static int regions_grow(void) {
|
||||
struct region_metadata *p = ra->regions == ro.regions[0] ?
|
||||
ro.regions[1] : ro.regions[0];
|
||||
|
||||
if (memory_protect_rw(p, newsize)) {
|
||||
if (memory_protect_rw_metadata(p, newsize)) {
|
||||
return 1;
|
||||
}
|
||||
|
||||
@ -767,6 +791,10 @@ COLD static void init_slow_path(void) {
|
||||
return;
|
||||
}
|
||||
|
||||
#ifdef USE_PKEY
|
||||
ro.metadata_pkey = pkey_alloc(0, 0);
|
||||
#endif
|
||||
|
||||
if (sysconf(_SC_PAGESIZE) != PAGE_SIZE) {
|
||||
fatal_error("page size mismatch");
|
||||
}
|
||||
@ -785,7 +813,7 @@ COLD static void init_slow_path(void) {
|
||||
if (allocator_state == NULL) {
|
||||
fatal_error("failed to reserve allocator state");
|
||||
}
|
||||
if (memory_protect_rw(allocator_state, offsetof(struct allocator_state, regions_a))) {
|
||||
if (memory_protect_rw_metadata(allocator_state, offsetof(struct allocator_state, regions_a))) {
|
||||
fatal_error("failed to unprotect allocator state");
|
||||
}
|
||||
|
||||
@ -799,7 +827,7 @@ COLD static void init_slow_path(void) {
|
||||
ra->regions = ro.regions[0];
|
||||
ra->total = INITIAL_REGION_TABLE_SIZE;
|
||||
ra->free = INITIAL_REGION_TABLE_SIZE;
|
||||
if (memory_protect_rw(ra->regions, ra->total * sizeof(struct region_metadata))) {
|
||||
if (memory_protect_rw_metadata(ra->regions, ra->total * sizeof(struct region_metadata))) {
|
||||
fatal_error("failed to unprotect memory for regions table");
|
||||
}
|
||||
|
||||
@ -891,6 +919,7 @@ static void *allocate(size_t size) {
|
||||
|
||||
static void deallocate_large(void *p, const size_t *expected_size) {
|
||||
enforce_init();
|
||||
thread_unseal_metadata();
|
||||
|
||||
struct region_allocator *ra = ro.region_allocator;
|
||||
|
||||
@ -919,8 +948,11 @@ static size_t adjust_size_for_canaries(size_t size) {
|
||||
|
||||
EXPORT void *h_malloc(size_t size) {
|
||||
init();
|
||||
thread_unseal_metadata();
|
||||
size = adjust_size_for_canaries(size);
|
||||
return allocate(size);
|
||||
void *p = allocate(size);
|
||||
thread_seal_metadata();
|
||||
return p;
|
||||
}
|
||||
|
||||
EXPORT void *h_calloc(size_t nmemb, size_t size) {
|
||||
@ -930,11 +962,15 @@ EXPORT void *h_calloc(size_t nmemb, size_t size) {
|
||||
return NULL;
|
||||
}
|
||||
init();
|
||||
thread_unseal_metadata();
|
||||
total_size = adjust_size_for_canaries(total_size);
|
||||
if (ZERO_ON_FREE) {
|
||||
return allocate(total_size);
|
||||
void *p = allocate(total_size);
|
||||
thread_seal_metadata();
|
||||
return p;
|
||||
}
|
||||
void *p = allocate(total_size);
|
||||
thread_seal_metadata();
|
||||
if (unlikely(p == NULL)) {
|
||||
return NULL;
|
||||
}
|
||||
@ -952,8 +988,11 @@ static_assert(MREMAP_MOVE_THRESHOLD >= REGION_QUARANTINE_SKIP_THRESHOLD,
|
||||
EXPORT void *h_realloc(void *old, size_t size) {
|
||||
if (old == NULL) {
|
||||
init();
|
||||
thread_unseal_metadata();
|
||||
size = adjust_size_for_canaries(size);
|
||||
return allocate(size);
|
||||
void *p = allocate(size);
|
||||
thread_seal_metadata();
|
||||
return p;
|
||||
}
|
||||
|
||||
size = adjust_size_for_canaries(size);
|
||||
@ -965,8 +1004,10 @@ EXPORT void *h_realloc(void *old, size_t size) {
|
||||
return old;
|
||||
}
|
||||
enforce_init();
|
||||
thread_unseal_metadata();
|
||||
} else {
|
||||
enforce_init();
|
||||
thread_unseal_metadata();
|
||||
|
||||
struct region_allocator *ra = ro.region_allocator;
|
||||
|
||||
@ -980,6 +1021,7 @@ EXPORT void *h_realloc(void *old, size_t size) {
|
||||
if (PAGE_CEILING(old_size) == PAGE_CEILING(size)) {
|
||||
region->size = size;
|
||||
mutex_unlock(&ra->lock);
|
||||
thread_seal_metadata();
|
||||
return old;
|
||||
}
|
||||
mutex_unlock(&ra->lock);
|
||||
@ -992,6 +1034,7 @@ EXPORT void *h_realloc(void *old, size_t size) {
|
||||
if (size < old_size) {
|
||||
void *new_end = (char *)old + rounded_size;
|
||||
if (memory_map_fixed(new_end, old_guard_size)) {
|
||||
thread_seal_metadata();
|
||||
return NULL;
|
||||
}
|
||||
void *new_guard_end = (char *)new_end + old_guard_size;
|
||||
@ -1005,6 +1048,7 @@ EXPORT void *h_realloc(void *old, size_t size) {
|
||||
region->size = size;
|
||||
mutex_unlock(&ra->lock);
|
||||
|
||||
thread_seal_metadata();
|
||||
return old;
|
||||
}
|
||||
|
||||
@ -1023,6 +1067,7 @@ EXPORT void *h_realloc(void *old, size_t size) {
|
||||
region->size = size;
|
||||
mutex_unlock(&ra->lock);
|
||||
|
||||
thread_seal_metadata();
|
||||
return old;
|
||||
}
|
||||
}
|
||||
@ -1031,6 +1076,7 @@ EXPORT void *h_realloc(void *old, size_t size) {
|
||||
if (copy_size >= MREMAP_MOVE_THRESHOLD) {
|
||||
void *new = allocate(size);
|
||||
if (new == NULL) {
|
||||
thread_seal_metadata();
|
||||
return NULL;
|
||||
}
|
||||
|
||||
@ -1049,6 +1095,7 @@ EXPORT void *h_realloc(void *old, size_t size) {
|
||||
memory_unmap((char *)old - old_guard_size, old_guard_size);
|
||||
memory_unmap((char *)old + PAGE_CEILING(old_size), old_guard_size);
|
||||
}
|
||||
thread_seal_metadata();
|
||||
return new;
|
||||
}
|
||||
}
|
||||
@ -1056,6 +1103,7 @@ EXPORT void *h_realloc(void *old, size_t size) {
|
||||
|
||||
void *new = allocate(size);
|
||||
if (new == NULL) {
|
||||
thread_seal_metadata();
|
||||
return NULL;
|
||||
}
|
||||
size_t copy_size = min(size, old_size);
|
||||
@ -1068,6 +1116,7 @@ EXPORT void *h_realloc(void *old, size_t size) {
|
||||
} else {
|
||||
deallocate_large(old, NULL);
|
||||
}
|
||||
thread_seal_metadata();
|
||||
return new;
|
||||
}
|
||||
|
||||
@ -1124,22 +1173,31 @@ static void *alloc_aligned_simple(size_t alignment, size_t size) {
|
||||
|
||||
EXPORT int h_posix_memalign(void **memptr, size_t alignment, size_t size) {
|
||||
init();
|
||||
thread_unseal_metadata();
|
||||
size = adjust_size_for_canaries(size);
|
||||
return alloc_aligned(memptr, alignment, size, sizeof(void *));
|
||||
int ret = alloc_aligned(memptr, alignment, size, sizeof(void *));
|
||||
thread_seal_metadata();
|
||||
return ret;
|
||||
}
|
||||
|
||||
EXPORT void *h_aligned_alloc(size_t alignment, size_t size) {
|
||||
init();
|
||||
thread_unseal_metadata();
|
||||
size = adjust_size_for_canaries(size);
|
||||
return alloc_aligned_simple(alignment, size);
|
||||
void *p = alloc_aligned_simple(alignment, size);
|
||||
thread_seal_metadata();
|
||||
return p;
|
||||
}
|
||||
|
||||
EXPORT void *h_memalign(size_t alignment, size_t size) ALIAS(h_aligned_alloc);
|
||||
|
||||
EXPORT void *h_valloc(size_t size) {
|
||||
init();
|
||||
thread_unseal_metadata();
|
||||
size = adjust_size_for_canaries(size);
|
||||
return alloc_aligned_simple(PAGE_SIZE, size);
|
||||
void *p = alloc_aligned_simple(PAGE_SIZE, size);
|
||||
thread_seal_metadata();
|
||||
return p;
|
||||
}
|
||||
|
||||
EXPORT void *h_pvalloc(size_t size) {
|
||||
@ -1149,8 +1207,11 @@ EXPORT void *h_pvalloc(size_t size) {
|
||||
return NULL;
|
||||
}
|
||||
init();
|
||||
thread_unseal_metadata();
|
||||
size = adjust_size_for_canaries(size);
|
||||
return alloc_aligned_simple(PAGE_SIZE, size);
|
||||
void *p = alloc_aligned_simple(PAGE_SIZE, size);
|
||||
thread_seal_metadata();
|
||||
return p;
|
||||
}
|
||||
|
||||
EXPORT void h_free(void *p) {
|
||||
@ -1159,11 +1220,14 @@ EXPORT void h_free(void *p) {
|
||||
}
|
||||
|
||||
if (p >= ro.slab_region_start && p < ro.slab_region_end) {
|
||||
thread_unseal_metadata();
|
||||
deallocate_small(p, NULL);
|
||||
return;
|
||||
}
|
||||
|
||||
deallocate_large(p, NULL);
|
||||
|
||||
thread_seal_metadata();
|
||||
}
|
||||
|
||||
EXPORT void h_cfree(void *ptr) ALIAS(h_free);
|
||||
@ -1174,12 +1238,15 @@ EXPORT void h_free_sized(void *p, size_t expected_size) {
|
||||
}
|
||||
|
||||
if (p >= ro.slab_region_start && p < ro.slab_region_end) {
|
||||
thread_unseal_metadata();
|
||||
expected_size = get_size_info(adjust_size_for_canaries(expected_size)).size;
|
||||
deallocate_small(p, &expected_size);
|
||||
return;
|
||||
}
|
||||
|
||||
deallocate_large(p, &expected_size);
|
||||
|
||||
thread_seal_metadata();
|
||||
}
|
||||
|
||||
EXPORT size_t h_malloc_usable_size(void *p) {
|
||||
@ -1193,6 +1260,7 @@ EXPORT size_t h_malloc_usable_size(void *p) {
|
||||
}
|
||||
|
||||
enforce_init();
|
||||
thread_unseal_metadata();
|
||||
|
||||
struct region_allocator *ra = ro.region_allocator;
|
||||
mutex_lock(&ra->lock);
|
||||
@ -1203,6 +1271,7 @@ EXPORT size_t h_malloc_usable_size(void *p) {
|
||||
size_t size = region->size;
|
||||
mutex_unlock(&ra->lock);
|
||||
|
||||
thread_seal_metadata();
|
||||
return size;
|
||||
}
|
||||
|
||||
@ -1220,12 +1289,15 @@ EXPORT size_t h_malloc_object_size(void *p) {
|
||||
return 0;
|
||||
}
|
||||
|
||||
thread_unseal_metadata();
|
||||
|
||||
struct region_allocator *ra = ro.region_allocator;
|
||||
mutex_lock(&ra->lock);
|
||||
struct region_metadata *region = regions_find(p);
|
||||
size_t size = p == NULL ? SIZE_MAX : region->size;
|
||||
mutex_unlock(&ra->lock);
|
||||
|
||||
thread_seal_metadata();
|
||||
return size;
|
||||
}
|
||||
|
||||
@ -1255,6 +1327,8 @@ EXPORT int h_malloc_trim(UNUSED size_t pad) {
|
||||
return 0;
|
||||
}
|
||||
|
||||
thread_unseal_metadata();
|
||||
|
||||
bool is_trimmed = false;
|
||||
|
||||
// skip zero byte size class since there's nothing to change
|
||||
@ -1282,6 +1356,8 @@ EXPORT int h_malloc_trim(UNUSED size_t pad) {
|
||||
mutex_unlock(&c->lock);
|
||||
}
|
||||
|
||||
thread_seal_metadata();
|
||||
|
||||
return is_trimmed;
|
||||
}
|
||||
|
||||
@ -1331,11 +1407,15 @@ COLD EXPORT int h_iterate(UNUSED uintptr_t base, UNUSED size_t size,
|
||||
|
||||
COLD EXPORT void h_malloc_disable(void) {
|
||||
init();
|
||||
thread_unseal_metadata();
|
||||
full_lock();
|
||||
thread_seal_metadata();
|
||||
}
|
||||
|
||||
COLD EXPORT void h_malloc_enable(void) {
|
||||
init();
|
||||
thread_unseal_metadata();
|
||||
full_unlock();
|
||||
thread_seal_metadata();
|
||||
}
|
||||
#endif
|
||||
|
18
memory.c
18
memory.c
@ -35,20 +35,28 @@ int memory_unmap(void *ptr, size_t size) {
|
||||
return ret;
|
||||
}
|
||||
|
||||
static int memory_protect_prot(void *ptr, size_t size, int prot) {
|
||||
static int memory_protect_prot(void *ptr, size_t size, int prot, UNUSED int pkey) {
|
||||
#ifdef USE_PKEY
|
||||
int ret = pkey_mprotect(ptr, size, prot, pkey);
|
||||
#else
|
||||
int ret = mprotect(ptr, size, prot);
|
||||
#endif
|
||||
if (unlikely(ret) && errno != ENOMEM) {
|
||||
fatal_error("non-ENOMEM mprotect failure");
|
||||
}
|
||||
return ret;
|
||||
}
|
||||
|
||||
int memory_protect_rw(void *ptr, size_t size) {
|
||||
return memory_protect_prot(ptr, size, PROT_READ|PROT_WRITE);
|
||||
int memory_protect_ro(void *ptr, size_t size) {
|
||||
return memory_protect_prot(ptr, size, PROT_READ, -1);
|
||||
}
|
||||
|
||||
int memory_protect_ro(void *ptr, size_t size) {
|
||||
return memory_protect_prot(ptr, size, PROT_READ);
|
||||
int memory_protect_rw(void *ptr, size_t size) {
|
||||
return memory_protect_prot(ptr, size, PROT_READ|PROT_WRITE, -1);
|
||||
}
|
||||
|
||||
int memory_protect_rw_metadata(void *ptr, size_t size) {
|
||||
return memory_protect_prot(ptr, size, PROT_READ|PROT_WRITE, get_metadata_key());
|
||||
}
|
||||
|
||||
int memory_remap(void *old, size_t old_size, size_t new_size) {
|
||||
|
5
memory.h
5
memory.h
@ -3,11 +3,14 @@
|
||||
|
||||
#include <stddef.h>
|
||||
|
||||
int get_metadata_key(void);
|
||||
|
||||
void *memory_map(size_t size);
|
||||
int memory_map_fixed(void *ptr, size_t size);
|
||||
int memory_unmap(void *ptr, size_t size);
|
||||
int memory_protect_rw(void *ptr, size_t size);
|
||||
int memory_protect_ro(void *ptr, size_t size);
|
||||
int memory_protect_rw(void *ptr, size_t size);
|
||||
int memory_protect_rw_metadata(void *ptr, size_t size);
|
||||
int memory_remap(void *old, size_t old_size, size_t new_size);
|
||||
int memory_remap_fixed(void *old, size_t old_size, void *new, size_t new_size);
|
||||
|
||||
|
8
util.h
8
util.h
@ -38,4 +38,12 @@ typedef uint32_t u32;
|
||||
typedef uint64_t u64;
|
||||
typedef unsigned __int128 u128;
|
||||
|
||||
#ifdef CONFIG_SEAL_METADATA
|
||||
#if defined(__GLIBC__) && __GLIBC_PREREQ(2, 27) && defined(__x86_64__)
|
||||
#define USE_PKEY
|
||||
#else
|
||||
#error "CONFIG_SEAL_METADATA requires Memory Protection Key support"
|
||||
#endif
|
||||
#endif
|
||||
|
||||
#endif
|
||||
|
Loading…
Reference in New Issue
Block a user