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47e34cb74d
BPF_PTR_POISON was added in commit c0a5a21c25 ("bpf: Allow storing
referenced kptr in map") to denote a bpf_func_proto btf_id which the
verifier will replace with a dynamically-determined btf_id at verification
time.
This patch adds verifier 'poison' functionality to BPF_PTR_POISON in
order to prepare for expanded use of the value to poison ret- and
arg-btf_id in ongoing work, namely rbtree and linked list patchsets
[0, 1]. Specifically, when the verifier checks helper calls, it assumes
that BPF_PTR_POISON'ed ret type will be replaced with a valid type before
- or in lieu of - the default ret_btf_id logic. Similarly for arg btf_id.
If poisoned btf_id reaches default handling block for either, consider
this a verifier internal error and fail verification. Otherwise a helper
w/ poisoned btf_id but no verifier logic replacing the type will cause a
crash as the invalid pointer is dereferenced.
Also move BPF_PTR_POISON to existing include/linux/posion.h header and
remove unnecessary shift.
[0]: lore.kernel.org/bpf/20220830172759.4069786-1-davemarchevsky@fb.com
[1]: lore.kernel.org/bpf/20220904204145.3089-1-memxor@gmail.com
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220912154544.1398199-1-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
88 lines
2.6 KiB
C
88 lines
2.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_POISON_H
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#define _LINUX_POISON_H
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/********** include/linux/list.h **********/
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/*
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* Architectures might want to move the poison pointer offset
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* into some well-recognized area such as 0xdead000000000000,
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* that is also not mappable by user-space exploits:
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*/
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#ifdef CONFIG_ILLEGAL_POINTER_VALUE
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# define POISON_POINTER_DELTA _AC(CONFIG_ILLEGAL_POINTER_VALUE, UL)
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#else
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# define POISON_POINTER_DELTA 0
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#endif
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/*
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* These are non-NULL pointers that will result in page faults
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* under normal circumstances, used to verify that nobody uses
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* non-initialized list entries.
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*/
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#define LIST_POISON1 ((void *) 0x100 + POISON_POINTER_DELTA)
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#define LIST_POISON2 ((void *) 0x122 + POISON_POINTER_DELTA)
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/********** include/linux/timer.h **********/
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#define TIMER_ENTRY_STATIC ((void *) 0x300 + POISON_POINTER_DELTA)
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/********** mm/page_poison.c **********/
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#define PAGE_POISON 0xaa
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/********** mm/page_alloc.c ************/
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#define TAIL_MAPPING ((void *) 0x400 + POISON_POINTER_DELTA)
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/********** mm/slab.c **********/
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/*
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* Magic nums for obj red zoning.
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* Placed in the first word before and the first word after an obj.
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*/
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#define RED_INACTIVE 0x09F911029D74E35BULL /* when obj is inactive */
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#define RED_ACTIVE 0xD84156C5635688C0ULL /* when obj is active */
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#define SLUB_RED_INACTIVE 0xbb
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#define SLUB_RED_ACTIVE 0xcc
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/* ...and for poisoning */
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#define POISON_INUSE 0x5a /* for use-uninitialised poisoning */
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#define POISON_FREE 0x6b /* for use-after-free poisoning */
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#define POISON_END 0xa5 /* end-byte of poisoning */
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/********** arch/$ARCH/mm/init.c **********/
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#define POISON_FREE_INITMEM 0xcc
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/********** arch/ia64/hp/common/sba_iommu.c **********/
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/*
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* arch/ia64/hp/common/sba_iommu.c uses a 16-byte poison string with a
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* value of "SBAIOMMU POISON\0" for spill-over poisoning.
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*/
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/********** fs/jbd/journal.c **********/
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#define JBD_POISON_FREE 0x5b
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#define JBD2_POISON_FREE 0x5c
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/********** drivers/base/dmapool.c **********/
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#define POOL_POISON_FREED 0xa7 /* !inuse */
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#define POOL_POISON_ALLOCATED 0xa9 /* !initted */
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/********** drivers/atm/ **********/
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#define ATM_POISON_FREE 0x12
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#define ATM_POISON 0xdeadbeef
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/********** kernel/mutexes **********/
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#define MUTEX_DEBUG_INIT 0x11
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#define MUTEX_DEBUG_FREE 0x22
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#define MUTEX_POISON_WW_CTX ((void *) 0x500 + POISON_POINTER_DELTA)
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/********** security/ **********/
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#define KEY_DESTROY 0xbd
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/********** net/core/page_pool.c **********/
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#define PP_SIGNATURE (0x40 + POISON_POINTER_DELTA)
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/********** kernel/bpf/ **********/
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#define BPF_PTR_POISON ((void *)(0xeB9FUL + POISON_POINTER_DELTA))
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#endif
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