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Add KFENCE test suite, testing various error detection scenarios. Makes use of KUnit for test organization. Since KFENCE's interface to obtain error reports is via the console, the test verifies that KFENCE outputs expected reports to the console. [elver@google.com: fix typo in test] Link: https://lkml.kernel.org/r/X9lHQExmHGvETxY4@elver.google.com [elver@google.com: show access type in report] Link: https://lkml.kernel.org/r/20210111091544.3287013-2-elver@google.com Link: https://lkml.kernel.org/r/20201103175841.3495947-9-elver@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Signed-off-by: Marco Elver <elver@google.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Co-developed-by: Alexander Potapenko <glider@google.com> Reviewed-by: Jann Horn <jannh@google.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: Christopher Lameter <cl@linux.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.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: Joern Engel <joern@purestorage.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kees Cook <keescook@chromium.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Pekka Enberg <penberg@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>
114 lines
3.3 KiB
C
114 lines
3.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Kernel Electric-Fence (KFENCE). For more info please see
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* Documentation/dev-tools/kfence.rst.
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*
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* Copyright (C) 2020, Google LLC.
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*/
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#ifndef MM_KFENCE_KFENCE_H
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#define MM_KFENCE_KFENCE_H
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/types.h>
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#include "../slab.h" /* for struct kmem_cache */
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/* For non-debug builds, avoid leaking kernel pointers into dmesg. */
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#ifdef CONFIG_DEBUG_KERNEL
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#define PTR_FMT "%px"
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#else
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#define PTR_FMT "%p"
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#endif
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/*
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* Get the canary byte pattern for @addr. Use a pattern that varies based on the
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* lower 3 bits of the address, to detect memory corruptions with higher
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* probability, where similar constants are used.
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*/
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#define KFENCE_CANARY_PATTERN(addr) ((u8)0xaa ^ (u8)((unsigned long)(addr) & 0x7))
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/* Maximum stack depth for reports. */
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#define KFENCE_STACK_DEPTH 64
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/* KFENCE object states. */
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enum kfence_object_state {
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KFENCE_OBJECT_UNUSED, /* Object is unused. */
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KFENCE_OBJECT_ALLOCATED, /* Object is currently allocated. */
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KFENCE_OBJECT_FREED, /* Object was allocated, and then freed. */
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};
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/* Alloc/free tracking information. */
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struct kfence_track {
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pid_t pid;
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int num_stack_entries;
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unsigned long stack_entries[KFENCE_STACK_DEPTH];
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};
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/* KFENCE metadata per guarded allocation. */
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struct kfence_metadata {
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struct list_head list; /* Freelist node; access under kfence_freelist_lock. */
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struct rcu_head rcu_head; /* For delayed freeing. */
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/*
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* Lock protecting below data; to ensure consistency of the below data,
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* since the following may execute concurrently: __kfence_alloc(),
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* __kfence_free(), kfence_handle_page_fault(). However, note that we
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* cannot grab the same metadata off the freelist twice, and multiple
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* __kfence_alloc() cannot run concurrently on the same metadata.
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*/
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raw_spinlock_t lock;
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/* The current state of the object; see above. */
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enum kfence_object_state state;
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/*
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* Allocated object address; cannot be calculated from size, because of
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* alignment requirements.
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*
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* Invariant: ALIGN_DOWN(addr, PAGE_SIZE) is constant.
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*/
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unsigned long addr;
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/*
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* The size of the original allocation.
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*/
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size_t size;
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/*
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* The kmem_cache cache of the last allocation; NULL if never allocated
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* or the cache has already been destroyed.
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*/
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struct kmem_cache *cache;
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/*
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* In case of an invalid access, the page that was unprotected; we
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* optimistically only store one address.
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*/
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unsigned long unprotected_page;
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/* Allocation and free stack information. */
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struct kfence_track alloc_track;
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struct kfence_track free_track;
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};
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extern struct kfence_metadata kfence_metadata[CONFIG_KFENCE_NUM_OBJECTS];
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/* KFENCE error types for report generation. */
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enum kfence_error_type {
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KFENCE_ERROR_OOB, /* Detected a out-of-bounds access. */
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KFENCE_ERROR_UAF, /* Detected a use-after-free access. */
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KFENCE_ERROR_CORRUPTION, /* Detected a memory corruption on free. */
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KFENCE_ERROR_INVALID, /* Invalid access of unknown type. */
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KFENCE_ERROR_INVALID_FREE, /* Invalid free. */
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};
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void kfence_report_error(unsigned long address, bool is_write, struct pt_regs *regs,
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const struct kfence_metadata *meta, enum kfence_error_type type);
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void kfence_print_object(struct seq_file *seq, const struct kfence_metadata *meta);
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#endif /* MM_KFENCE_KFENCE_H */
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