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d3fb45f370
Inserts KFENCE hooks into the SLAB allocator. To pass the originally requested size to KFENCE, add an argument 'orig_size' to slab_alloc*(). The additional argument is required to preserve the requested original size for kmalloc() allocations, which uses size classes (e.g. an allocation of 272 bytes will return an object of size 512). Therefore, kmem_cache::size does not represent the kmalloc-caller's requested size, and we must introduce the argument 'orig_size' to propagate the originally requested size to KFENCE. Without the originally requested size, we would not be able to detect out-of-bounds accesses for objects placed at the end of a KFENCE object page if that object is not equal to the kmalloc-size class it was bucketed into. When KFENCE is disabled, there is no additional overhead, since slab_alloc*() functions are __always_inline. Link: https://lkml.kernel.org/r/20201103175841.3495947-5-elver@google.com Signed-off-by: Marco Elver <elver@google.com> Signed-off-by: Alexander Potapenko <glider@google.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Co-developed-by: Marco Elver <elver@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Hillf Danton <hdanton@sina.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Joern Engel <joern@purestorage.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Kees Cook <keescook@chromium.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: SeongJae Park <sjpark@amazon.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
123 lines
3 KiB
C
123 lines
3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_SLAB_DEF_H
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#define _LINUX_SLAB_DEF_H
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#include <linux/kfence.h>
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#include <linux/reciprocal_div.h>
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/*
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* Definitions unique to the original Linux SLAB allocator.
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*/
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struct kmem_cache {
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struct array_cache __percpu *cpu_cache;
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/* 1) Cache tunables. Protected by slab_mutex */
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unsigned int batchcount;
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unsigned int limit;
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unsigned int shared;
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unsigned int size;
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struct reciprocal_value reciprocal_buffer_size;
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/* 2) touched by every alloc & free from the backend */
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slab_flags_t flags; /* constant flags */
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unsigned int num; /* # of objs per slab */
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/* 3) cache_grow/shrink */
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/* order of pgs per slab (2^n) */
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unsigned int gfporder;
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/* force GFP flags, e.g. GFP_DMA */
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gfp_t allocflags;
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size_t colour; /* cache colouring range */
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unsigned int colour_off; /* colour offset */
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struct kmem_cache *freelist_cache;
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unsigned int freelist_size;
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/* constructor func */
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void (*ctor)(void *obj);
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/* 4) cache creation/removal */
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const char *name;
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struct list_head list;
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int refcount;
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int object_size;
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int align;
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/* 5) statistics */
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#ifdef CONFIG_DEBUG_SLAB
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unsigned long num_active;
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unsigned long num_allocations;
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unsigned long high_mark;
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unsigned long grown;
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unsigned long reaped;
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unsigned long errors;
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unsigned long max_freeable;
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unsigned long node_allocs;
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unsigned long node_frees;
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unsigned long node_overflow;
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atomic_t allochit;
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atomic_t allocmiss;
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atomic_t freehit;
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atomic_t freemiss;
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/*
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* If debugging is enabled, then the allocator can add additional
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* fields and/or padding to every object. 'size' contains the total
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* object size including these internal fields, while 'obj_offset'
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* and 'object_size' contain the offset to the user object and its
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* size.
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*/
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int obj_offset;
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#endif /* CONFIG_DEBUG_SLAB */
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#ifdef CONFIG_KASAN
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struct kasan_cache kasan_info;
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#endif
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#ifdef CONFIG_SLAB_FREELIST_RANDOM
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unsigned int *random_seq;
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#endif
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unsigned int useroffset; /* Usercopy region offset */
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unsigned int usersize; /* Usercopy region size */
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struct kmem_cache_node *node[MAX_NUMNODES];
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};
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static inline void *nearest_obj(struct kmem_cache *cache, struct page *page,
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void *x)
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{
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void *object = x - (x - page->s_mem) % cache->size;
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void *last_object = page->s_mem + (cache->num - 1) * cache->size;
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if (unlikely(object > last_object))
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return last_object;
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else
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return object;
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}
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/*
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* We want to avoid an expensive divide : (offset / cache->size)
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* Using the fact that size is a constant for a particular cache,
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* we can replace (offset / cache->size) by
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* reciprocal_divide(offset, cache->reciprocal_buffer_size)
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*/
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static inline unsigned int obj_to_index(const struct kmem_cache *cache,
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const struct page *page, void *obj)
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{
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u32 offset = (obj - page->s_mem);
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return reciprocal_divide(offset, cache->reciprocal_buffer_size);
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}
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static inline int objs_per_slab_page(const struct kmem_cache *cache,
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const struct page *page)
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{
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if (is_kfence_address(page_address(page)))
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return 1;
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return cache->num;
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}
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#endif /* _LINUX_SLAB_DEF_H */
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