From: Dave Marchevsky <davemarchevsky@fb.com>
To: <bpf@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Kernel Team <kernel-team@fb.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Yonghong Song <yhs@fb.com>,
Dave Marchevsky <davemarchevsky@fb.com>
Subject: [PATCH v2 bpf-next 1/2] bpf: Allow ringbuf memory to be used as map key
Date: Wed, 14 Sep 2022 05:35:59 -0700 [thread overview]
Message-ID: <20220914123600.927632-1-davemarchevsky@fb.com> (raw)
This patch adds support for the following pattern:
struct some_data *data = bpf_ringbuf_reserve(&ringbuf, sizeof(struct some_data, 0));
if (!data)
return;
bpf_map_lookup_elem(&another_map, &data->some_field);
bpf_ringbuf_submit(data);
Currently the verifier does not consider bpf_ringbuf_reserve's
PTR_TO_MEM | MEM_ALLOC ret type a valid key input to bpf_map_lookup_elem.
Since PTR_TO_MEM is by definition a valid region of memory, it is safe
to use it as a key for lookups.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
---
v1->v2: lore.kernel.org/bpf/20220912101106.2765921-1-davemarchevsky@fb.com
* Move test changes into separate patch - patch 2 in this series.
(Kumar, Yonghong). That patch's changelog enumerates specific
changes from v1
* Remove PTR_TO_MEM addition from this patch - patch 1 (Yonghong)
* I don't have a usecase for PTR_TO_MEM w/o MEM_ALLOC
* Add "if (!data)" error check to example pattern in this patch
(Yonghong)
* Remove patch 2 from v1's series, which removed map_key_value_types
as it was more-or-less duplicate of mem_types
* Now that PTR_TO_MEM isn't added here, more differences between
map_key_value_types and mem_types, and no usecase for PTR_TO_BUF,
so drop for now.
kernel/bpf/verifier.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index c259d734f863..f6e029780698 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5626,6 +5626,7 @@ static const struct bpf_reg_types map_key_value_types = {
PTR_TO_PACKET_META,
PTR_TO_MAP_KEY,
PTR_TO_MAP_VALUE,
+ PTR_TO_MEM | MEM_ALLOC,
},
};
--
2.30.2
next reply other threads:[~2022-09-14 12:36 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-14 12:35 Dave Marchevsky [this message]
2022-09-14 12:36 ` [PATCH v2 bpf-next 2/2] selftests/bpf: Add test verifying bpf_ringbuf_reserve retval use in map ops Dave Marchevsky
2022-09-15 10:24 ` Alexei Starovoitov
2022-09-19 22:53 ` Yonghong Song
2022-09-19 23:22 ` Kumar Kartikeya Dwivedi
2022-09-20 5:50 ` Yonghong Song
2022-09-22 14:27 ` Dave Marchevsky
2022-09-22 16:59 ` Yonghong Song
2022-09-14 17:21 ` [PATCH v2 bpf-next 1/2] bpf: Allow ringbuf memory to be used as map key Yonghong Song
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