From: Song Liu <songliubraving@fb.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>, bpf <bpf@vger.kernel.org>,
Networking <netdev@vger.kernel.org>,
Alexei Starovoitov <ast@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Kernel Team <Kernel-team@fb.com>
Subject: Re: [PATCH bpf-next 07/11] libbpf: fix BTF data layout checks and allow empty BTF
Date: Tue, 3 Nov 2020 05:44:13 +0000 [thread overview]
Message-ID: <0ECC1C71-119A-489F-BE6B-B04329357A5B@fb.com> (raw)
In-Reply-To: <CAEf4Bzbwmbx=q7o03q99866sgSijtAjBMWWTbSCgshtv76otyQ@mail.gmail.com>
> On Nov 2, 2020, at 9:18 PM, Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote:
>
> On Mon, Nov 2, 2020 at 4:51 PM Song Liu <songliubraving@fb.com> wrote:
>>
>>
>>
>>> On Oct 28, 2020, at 5:58 PM, Andrii Nakryiko <andrii@kernel.org> wrote:
>>>
>>> Make data section layout checks stricter, disallowing overlap of types and
>>> strings data.
>>>
>>> Additionally, allow BTFs with no type data. There is nothing inherently wrong
>>> with having BTF with no types (put potentially with some strings). This could
>>> be a situation with kernel module BTFs, if module doesn't introduce any new
>>> type information.
>>>
>>> Also fix invalid offset alignment check for btf->hdr->type_off.
>>>
>>> Fixes: 8a138aed4a80 ("bpf: btf: Add BTF support to libbpf")
>>> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
>>> ---
>>> tools/lib/bpf/btf.c | 16 ++++++----------
>>> 1 file changed, 6 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
>>> index 20c64a8441a8..9b0ef71a03d0 100644
>>> --- a/tools/lib/bpf/btf.c
>>> +++ b/tools/lib/bpf/btf.c
>>> @@ -245,22 +245,18 @@ static int btf_parse_hdr(struct btf *btf)
>>> return -EINVAL;
>>> }
>>>
>>> - if (meta_left < hdr->type_off) {
>>> - pr_debug("Invalid BTF type section offset:%u\n", hdr->type_off);
>>> + if (meta_left < hdr->str_off + hdr->str_len) {
>>> + pr_debug("Invalid BTF total size:%u\n", btf->raw_size);
>>> return -EINVAL;
>>> }
>>
>> Can we make this one as
>> if (meta_left != hdr->str_off + hdr->str_len) {
>
> That would be not forward-compatible. I.e., old libbpf loading new BTF
> with extra stuff after the string section. Kernel is necessarily more
> strict, but I'd like to keep libbpf more permissive with this.
Yeah, this makes sense. Let's keep both checks AS-IS.
Thanks,
Song
next prev parent reply other threads:[~2020-11-03 5:44 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-29 0:58 [PATCH bpf-next 00/11] libbpf: split BTF support Andrii Nakryiko
2020-10-29 0:58 ` [PATCH bpf-next 01/11] libbpf: factor out common operations in BTF writing APIs Andrii Nakryiko
2020-10-30 0:36 ` Song Liu
2020-10-29 0:58 ` [PATCH bpf-next 02/11] selftest/bpf: relax btf_dedup test checks Andrii Nakryiko
2020-10-30 16:43 ` Song Liu
2020-10-30 18:44 ` Andrii Nakryiko
2020-10-30 22:30 ` Song Liu
2020-10-29 0:58 ` [PATCH bpf-next 03/11] libbpf: unify and speed up BTF string deduplication Andrii Nakryiko
2020-10-30 23:32 ` Song Liu
2020-11-03 4:51 ` Andrii Nakryiko
2020-11-03 4:59 ` Alexei Starovoitov
2020-11-03 6:01 ` Andrii Nakryiko
2020-10-29 0:58 ` [PATCH bpf-next 04/11] libbpf: implement basic split BTF support Andrii Nakryiko
2020-11-02 23:23 ` Song Liu
2020-11-03 5:02 ` Andrii Nakryiko
2020-11-03 5:41 ` Song Liu
2020-11-04 23:51 ` Andrii Nakryiko
2020-10-29 0:58 ` [PATCH bpf-next 05/11] selftests/bpf: add split BTF basic test Andrii Nakryiko
2020-11-02 23:36 ` Song Liu
2020-11-03 5:10 ` Andrii Nakryiko
2020-10-29 0:58 ` [PATCH bpf-next 06/11] selftests/bpf: add checking of raw type dump in BTF writer APIs selftests Andrii Nakryiko
2020-11-03 0:08 ` Song Liu
2020-11-03 5:14 ` Andrii Nakryiko
2020-10-29 0:58 ` [PATCH bpf-next 07/11] libbpf: fix BTF data layout checks and allow empty BTF Andrii Nakryiko
2020-11-03 0:51 ` Song Liu
2020-11-03 5:18 ` Andrii Nakryiko
2020-11-03 5:44 ` Song Liu [this message]
2020-10-29 0:58 ` [PATCH bpf-next 08/11] libbpf: support BTF dedup of split BTFs Andrii Nakryiko
2020-11-03 2:49 ` Song Liu
2020-11-03 5:25 ` Andrii Nakryiko
2020-11-03 5:59 ` Song Liu
2020-11-03 6:31 ` Andrii Nakryiko
2020-11-03 17:15 ` Song Liu
2020-11-03 5:10 ` Alexei Starovoitov
2020-11-03 6:27 ` Andrii Nakryiko
2020-11-03 17:55 ` Alexei Starovoitov
2020-10-29 0:59 ` [PATCH bpf-next 09/11] libbpf: accomodate DWARF/compiler bug with duplicated identical arrays Andrii Nakryiko
2020-11-03 2:52 ` Song Liu
2020-10-29 0:59 ` [PATCH bpf-next 10/11] selftests/bpf: add split BTF dedup selftests Andrii Nakryiko
2020-11-03 5:35 ` Song Liu
2020-11-03 6:05 ` Andrii Nakryiko
2020-11-03 6:30 ` Song Liu
2020-10-29 0:59 ` [PATCH bpf-next 11/11] tools/bpftool: add bpftool support for split BTF Andrii Nakryiko
2020-11-03 6:03 ` Song Liu
2020-10-30 0:33 ` [PATCH bpf-next 00/11] libbpf: split BTF support Song Liu
2020-10-30 2:33 ` Andrii Nakryiko
2020-10-30 6:45 ` Song Liu
2020-10-30 12:04 ` Alan Maguire
2020-10-30 18:30 ` Andrii Nakryiko
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