mirror of
https://github.com/torvalds/linux
synced 2024-09-06 18:01:05 +00:00
Merge branch 'slab/for-6.6/random_kmalloc' into slab/for-next
Merge the new hardening feature to make heap spraying harder, by GONG, Ruiqi. It creates multiple (16) copies of kmalloc caches, reducing the chance of an attacker-controllable allocation site to land in the same slab as e.g. an allocation site with use-after-free vulnerability. The selection of the copy is derived from the allocation site address, including a per-boot random seed. In line with SLAB deprecation, this is a SLUB only feature, incompatible with SLUB_TINY due to the memory overhead of the extra cache copies.
This commit is contained in:
commit
3d053e8060
|
@ -35,6 +35,12 @@
|
|||
#define PCPU_BITMAP_BLOCK_BITS (PCPU_BITMAP_BLOCK_SIZE >> \
|
||||
PCPU_MIN_ALLOC_SHIFT)
|
||||
|
||||
#ifdef CONFIG_RANDOM_KMALLOC_CACHES
|
||||
#define PERCPU_DYNAMIC_SIZE_SHIFT 12
|
||||
#else
|
||||
#define PERCPU_DYNAMIC_SIZE_SHIFT 10
|
||||
#endif
|
||||
|
||||
/*
|
||||
* Percpu allocator can serve percpu allocations before slab is
|
||||
* initialized which allows slab to depend on the percpu allocator.
|
||||
|
@ -42,7 +48,7 @@
|
|||
* for this. Keep PERCPU_DYNAMIC_RESERVE equal to or larger than
|
||||
* PERCPU_DYNAMIC_EARLY_SIZE.
|
||||
*/
|
||||
#define PERCPU_DYNAMIC_EARLY_SIZE (20 << 10)
|
||||
#define PERCPU_DYNAMIC_EARLY_SIZE (20 << PERCPU_DYNAMIC_SIZE_SHIFT)
|
||||
|
||||
/*
|
||||
* PERCPU_DYNAMIC_RESERVE indicates the amount of free area to piggy
|
||||
|
@ -56,9 +62,9 @@
|
|||
* intelligent way to determine this would be nice.
|
||||
*/
|
||||
#if BITS_PER_LONG > 32
|
||||
#define PERCPU_DYNAMIC_RESERVE (28 << 10)
|
||||
#define PERCPU_DYNAMIC_RESERVE (28 << PERCPU_DYNAMIC_SIZE_SHIFT)
|
||||
#else
|
||||
#define PERCPU_DYNAMIC_RESERVE (20 << 10)
|
||||
#define PERCPU_DYNAMIC_RESERVE (20 << PERCPU_DYNAMIC_SIZE_SHIFT)
|
||||
#endif
|
||||
|
||||
extern void *pcpu_base_addr;
|
||||
|
|
|
@ -19,6 +19,7 @@
|
|||
#include <linux/workqueue.h>
|
||||
#include <linux/percpu-refcount.h>
|
||||
#include <linux/cleanup.h>
|
||||
#include <linux/hash.h>
|
||||
|
||||
|
||||
/*
|
||||
|
@ -345,6 +346,12 @@ static inline unsigned int arch_slab_minalign(void)
|
|||
#define SLAB_OBJ_MIN_SIZE (KMALLOC_MIN_SIZE < 16 ? \
|
||||
(KMALLOC_MIN_SIZE) : 16)
|
||||
|
||||
#ifdef CONFIG_RANDOM_KMALLOC_CACHES
|
||||
#define RANDOM_KMALLOC_CACHES_NR 15 // # of cache copies
|
||||
#else
|
||||
#define RANDOM_KMALLOC_CACHES_NR 0
|
||||
#endif
|
||||
|
||||
/*
|
||||
* Whenever changing this, take care of that kmalloc_type() and
|
||||
* create_kmalloc_caches() still work as intended.
|
||||
|
@ -361,6 +368,8 @@ enum kmalloc_cache_type {
|
|||
#ifndef CONFIG_MEMCG_KMEM
|
||||
KMALLOC_CGROUP = KMALLOC_NORMAL,
|
||||
#endif
|
||||
KMALLOC_RANDOM_START = KMALLOC_NORMAL,
|
||||
KMALLOC_RANDOM_END = KMALLOC_RANDOM_START + RANDOM_KMALLOC_CACHES_NR,
|
||||
#ifdef CONFIG_SLUB_TINY
|
||||
KMALLOC_RECLAIM = KMALLOC_NORMAL,
|
||||
#else
|
||||
|
@ -386,14 +395,22 @@ kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1];
|
|||
(IS_ENABLED(CONFIG_ZONE_DMA) ? __GFP_DMA : 0) | \
|
||||
(IS_ENABLED(CONFIG_MEMCG_KMEM) ? __GFP_ACCOUNT : 0))
|
||||
|
||||
static __always_inline enum kmalloc_cache_type kmalloc_type(gfp_t flags)
|
||||
extern unsigned long random_kmalloc_seed;
|
||||
|
||||
static __always_inline enum kmalloc_cache_type kmalloc_type(gfp_t flags, unsigned long caller)
|
||||
{
|
||||
/*
|
||||
* The most common case is KMALLOC_NORMAL, so test for it
|
||||
* with a single branch for all the relevant flags.
|
||||
*/
|
||||
if (likely((flags & KMALLOC_NOT_NORMAL_BITS) == 0))
|
||||
#ifdef CONFIG_RANDOM_KMALLOC_CACHES
|
||||
/* RANDOM_KMALLOC_CACHES_NR (=15) copies + the KMALLOC_NORMAL */
|
||||
return KMALLOC_RANDOM_START + hash_64(caller ^ random_kmalloc_seed,
|
||||
ilog2(RANDOM_KMALLOC_CACHES_NR + 1));
|
||||
#else
|
||||
return KMALLOC_NORMAL;
|
||||
#endif
|
||||
|
||||
/*
|
||||
* At least one of the flags has to be set. Their priorities in
|
||||
|
@ -580,7 +597,7 @@ static __always_inline __alloc_size(1) void *kmalloc(size_t size, gfp_t flags)
|
|||
|
||||
index = kmalloc_index(size);
|
||||
return kmalloc_trace(
|
||||
kmalloc_caches[kmalloc_type(flags)][index],
|
||||
kmalloc_caches[kmalloc_type(flags, _RET_IP_)][index],
|
||||
flags, size);
|
||||
}
|
||||
return __kmalloc(size, flags);
|
||||
|
@ -596,7 +613,7 @@ static __always_inline __alloc_size(1) void *kmalloc_node(size_t size, gfp_t fla
|
|||
|
||||
index = kmalloc_index(size);
|
||||
return kmalloc_node_trace(
|
||||
kmalloc_caches[kmalloc_type(flags)][index],
|
||||
kmalloc_caches[kmalloc_type(flags, _RET_IP_)][index],
|
||||
flags, node, size);
|
||||
}
|
||||
return __kmalloc_node(size, flags, node);
|
||||
|
|
17
mm/Kconfig
17
mm/Kconfig
|
@ -337,6 +337,23 @@ config SLUB_CPU_PARTIAL
|
|||
which requires the taking of locks that may cause latency spikes.
|
||||
Typically one would choose no for a realtime system.
|
||||
|
||||
config RANDOM_KMALLOC_CACHES
|
||||
default n
|
||||
depends on SLUB && !SLUB_TINY
|
||||
bool "Randomize slab caches for normal kmalloc"
|
||||
help
|
||||
A hardening feature that creates multiple copies of slab caches for
|
||||
normal kmalloc allocation and makes kmalloc randomly pick one based
|
||||
on code address, which makes the attackers more difficult to spray
|
||||
vulnerable memory objects on the heap for the purpose of exploiting
|
||||
memory vulnerabilities.
|
||||
|
||||
Currently the number of copies is set to 16, a reasonably large value
|
||||
that effectively diverges the memory objects allocated for different
|
||||
subsystems or modules into different caches, at the expense of a
|
||||
limited degree of memory and CPU overhead that relates to hardware and
|
||||
system workload.
|
||||
|
||||
endmenu # SLAB allocator options
|
||||
|
||||
config SHUFFLE_PAGE_ALLOCATOR
|
||||
|
|
|
@ -212,7 +212,9 @@ static void test_cache_destroy(void)
|
|||
|
||||
static inline size_t kmalloc_cache_alignment(size_t size)
|
||||
{
|
||||
return kmalloc_caches[kmalloc_type(GFP_KERNEL)][__kmalloc_index(size, false)]->align;
|
||||
/* just to get ->align so no need to pass in the real caller */
|
||||
enum kmalloc_cache_type type = kmalloc_type(GFP_KERNEL, 0);
|
||||
return kmalloc_caches[type][__kmalloc_index(size, false)]->align;
|
||||
}
|
||||
|
||||
/* Must always inline to match stack trace against caller. */
|
||||
|
@ -282,8 +284,9 @@ static void *test_alloc(struct kunit *test, size_t size, gfp_t gfp, enum allocat
|
|||
|
||||
if (is_kfence_address(alloc)) {
|
||||
struct slab *slab = virt_to_slab(alloc);
|
||||
enum kmalloc_cache_type type = kmalloc_type(GFP_KERNEL, _RET_IP_);
|
||||
struct kmem_cache *s = test_cache ?:
|
||||
kmalloc_caches[kmalloc_type(GFP_KERNEL)][__kmalloc_index(size, false)];
|
||||
kmalloc_caches[type][__kmalloc_index(size, false)];
|
||||
|
||||
/*
|
||||
* Verify that various helpers return the right values
|
||||
|
|
|
@ -1670,7 +1670,7 @@ static size_t calculate_slab_order(struct kmem_cache *cachep,
|
|||
if (freelist_size > KMALLOC_MAX_CACHE_SIZE) {
|
||||
freelist_cache_size = PAGE_SIZE << get_order(freelist_size);
|
||||
} else {
|
||||
freelist_cache = kmalloc_slab(freelist_size, 0u);
|
||||
freelist_cache = kmalloc_slab(freelist_size, 0u, _RET_IP_);
|
||||
if (!freelist_cache)
|
||||
continue;
|
||||
freelist_cache_size = freelist_cache->size;
|
||||
|
|
|
@ -282,7 +282,7 @@ void setup_kmalloc_cache_index_table(void);
|
|||
void create_kmalloc_caches(slab_flags_t);
|
||||
|
||||
/* Find the kmalloc slab corresponding for a certain size */
|
||||
struct kmem_cache *kmalloc_slab(size_t, gfp_t);
|
||||
struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags, unsigned long caller);
|
||||
|
||||
void *__kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags,
|
||||
int node, size_t orig_size,
|
||||
|
|
|
@ -678,6 +678,11 @@ kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1] __ro_after_init =
|
|||
{ /* initialization for https://bugs.llvm.org/show_bug.cgi?id=42570 */ };
|
||||
EXPORT_SYMBOL(kmalloc_caches);
|
||||
|
||||
#ifdef CONFIG_RANDOM_KMALLOC_CACHES
|
||||
unsigned long random_kmalloc_seed __ro_after_init;
|
||||
EXPORT_SYMBOL(random_kmalloc_seed);
|
||||
#endif
|
||||
|
||||
/*
|
||||
* Conversion table for small slabs sizes / 8 to the index in the
|
||||
* kmalloc array. This is necessary for slabs < 192 since we have non power
|
||||
|
@ -720,7 +725,7 @@ static inline unsigned int size_index_elem(unsigned int bytes)
|
|||
* Find the kmem_cache structure that serves a given size of
|
||||
* allocation
|
||||
*/
|
||||
struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
|
||||
struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags, unsigned long caller)
|
||||
{
|
||||
unsigned int index;
|
||||
|
||||
|
@ -735,7 +740,7 @@ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
|
|||
index = fls(size - 1);
|
||||
}
|
||||
|
||||
return kmalloc_caches[kmalloc_type(flags)][index];
|
||||
return kmalloc_caches[kmalloc_type(flags, caller)][index];
|
||||
}
|
||||
|
||||
size_t kmalloc_size_roundup(size_t size)
|
||||
|
@ -752,8 +757,11 @@ size_t kmalloc_size_roundup(size_t size)
|
|||
if (size > KMALLOC_MAX_CACHE_SIZE)
|
||||
return PAGE_SIZE << get_order(size);
|
||||
|
||||
/* The flags don't matter since size_index is common to all. */
|
||||
c = kmalloc_slab(size, GFP_KERNEL);
|
||||
/*
|
||||
* The flags don't matter since size_index is common to all.
|
||||
* Neither does the caller for just getting ->object_size.
|
||||
*/
|
||||
c = kmalloc_slab(size, GFP_KERNEL, 0);
|
||||
return c ? c->object_size : 0;
|
||||
}
|
||||
EXPORT_SYMBOL(kmalloc_size_roundup);
|
||||
|
@ -776,12 +784,35 @@ EXPORT_SYMBOL(kmalloc_size_roundup);
|
|||
#define KMALLOC_RCL_NAME(sz)
|
||||
#endif
|
||||
|
||||
#ifdef CONFIG_RANDOM_KMALLOC_CACHES
|
||||
#define __KMALLOC_RANDOM_CONCAT(a, b) a ## b
|
||||
#define KMALLOC_RANDOM_NAME(N, sz) __KMALLOC_RANDOM_CONCAT(KMA_RAND_, N)(sz)
|
||||
#define KMA_RAND_1(sz) .name[KMALLOC_RANDOM_START + 1] = "kmalloc-rnd-01-" #sz,
|
||||
#define KMA_RAND_2(sz) KMA_RAND_1(sz) .name[KMALLOC_RANDOM_START + 2] = "kmalloc-rnd-02-" #sz,
|
||||
#define KMA_RAND_3(sz) KMA_RAND_2(sz) .name[KMALLOC_RANDOM_START + 3] = "kmalloc-rnd-03-" #sz,
|
||||
#define KMA_RAND_4(sz) KMA_RAND_3(sz) .name[KMALLOC_RANDOM_START + 4] = "kmalloc-rnd-04-" #sz,
|
||||
#define KMA_RAND_5(sz) KMA_RAND_4(sz) .name[KMALLOC_RANDOM_START + 5] = "kmalloc-rnd-05-" #sz,
|
||||
#define KMA_RAND_6(sz) KMA_RAND_5(sz) .name[KMALLOC_RANDOM_START + 6] = "kmalloc-rnd-06-" #sz,
|
||||
#define KMA_RAND_7(sz) KMA_RAND_6(sz) .name[KMALLOC_RANDOM_START + 7] = "kmalloc-rnd-07-" #sz,
|
||||
#define KMA_RAND_8(sz) KMA_RAND_7(sz) .name[KMALLOC_RANDOM_START + 8] = "kmalloc-rnd-08-" #sz,
|
||||
#define KMA_RAND_9(sz) KMA_RAND_8(sz) .name[KMALLOC_RANDOM_START + 9] = "kmalloc-rnd-09-" #sz,
|
||||
#define KMA_RAND_10(sz) KMA_RAND_9(sz) .name[KMALLOC_RANDOM_START + 10] = "kmalloc-rnd-10-" #sz,
|
||||
#define KMA_RAND_11(sz) KMA_RAND_10(sz) .name[KMALLOC_RANDOM_START + 11] = "kmalloc-rnd-11-" #sz,
|
||||
#define KMA_RAND_12(sz) KMA_RAND_11(sz) .name[KMALLOC_RANDOM_START + 12] = "kmalloc-rnd-12-" #sz,
|
||||
#define KMA_RAND_13(sz) KMA_RAND_12(sz) .name[KMALLOC_RANDOM_START + 13] = "kmalloc-rnd-13-" #sz,
|
||||
#define KMA_RAND_14(sz) KMA_RAND_13(sz) .name[KMALLOC_RANDOM_START + 14] = "kmalloc-rnd-14-" #sz,
|
||||
#define KMA_RAND_15(sz) KMA_RAND_14(sz) .name[KMALLOC_RANDOM_START + 15] = "kmalloc-rnd-15-" #sz,
|
||||
#else // CONFIG_RANDOM_KMALLOC_CACHES
|
||||
#define KMALLOC_RANDOM_NAME(N, sz)
|
||||
#endif
|
||||
|
||||
#define INIT_KMALLOC_INFO(__size, __short_size) \
|
||||
{ \
|
||||
.name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \
|
||||
KMALLOC_RCL_NAME(__short_size) \
|
||||
KMALLOC_CGROUP_NAME(__short_size) \
|
||||
KMALLOC_DMA_NAME(__short_size) \
|
||||
KMALLOC_RANDOM_NAME(RANDOM_KMALLOC_CACHES_NR, __short_size) \
|
||||
.size = __size, \
|
||||
}
|
||||
|
||||
|
@ -890,6 +921,11 @@ new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags)
|
|||
flags |= SLAB_CACHE_DMA;
|
||||
}
|
||||
|
||||
#ifdef CONFIG_RANDOM_KMALLOC_CACHES
|
||||
if (type >= KMALLOC_RANDOM_START && type <= KMALLOC_RANDOM_END)
|
||||
flags |= SLAB_NO_MERGE;
|
||||
#endif
|
||||
|
||||
/*
|
||||
* If CONFIG_MEMCG_KMEM is enabled, disable cache merging for
|
||||
* KMALLOC_NORMAL caches.
|
||||
|
@ -941,6 +977,9 @@ void __init create_kmalloc_caches(slab_flags_t flags)
|
|||
new_kmalloc_cache(2, type, flags);
|
||||
}
|
||||
}
|
||||
#ifdef CONFIG_RANDOM_KMALLOC_CACHES
|
||||
random_kmalloc_seed = get_random_u64();
|
||||
#endif
|
||||
|
||||
/* Kmalloc array is now usable */
|
||||
slab_state = UP;
|
||||
|
@ -976,7 +1015,7 @@ void *__do_kmalloc_node(size_t size, gfp_t flags, int node, unsigned long caller
|
|||
return ret;
|
||||
}
|
||||
|
||||
s = kmalloc_slab(size, flags);
|
||||
s = kmalloc_slab(size, flags, caller);
|
||||
|
||||
if (unlikely(ZERO_OR_NULL_PTR(s)))
|
||||
return s;
|
||||
|
|
Loading…
Reference in a new issue