From: Alexei Starovoitov <ast@fb.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>,
Alexei Starovoitov <ast@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>,
Daniel Borkmann <daniel@iogearbox.net>,
"x86@kernel.org" <x86@kernel.org>,
Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
Kernel Team <Kernel-team@fb.com>
Subject: Re: [PATCH bpf-next 04/10] libbpf: auto-detect btf_id of raw_tracepoint
Date: Wed, 9 Oct 2019 02:26:58 +0000 [thread overview]
Message-ID: <0ea6bf09-12ca-e23a-0535-abc62ee7e914@fb.com> (raw)
In-Reply-To: <CAEf4BzZxHyBoX9stW7uapZ06xd26N_zZcghytkQAUM1ss5sN6A@mail.gmail.com>
On 10/7/19 4:41 PM, Andrii Nakryiko wrote:
> On Fri, Oct 4, 2019 at 10:04 PM Alexei Starovoitov <ast@kernel.org> wrote:
>>
>> For raw tracepoint program types libbpf will try to find
>> btf_id of raw tracepoint in vmlinux's BTF.
>> It's a responsiblity of bpf program author to annotate the program
>> with SEC("raw_tracepoint/name") where "name" is a valid raw tracepoint.
>
> As an aside, I've been thinking about allowing to specify "raw_tp/"
> and "tp/" in section name as an "alias" for "raw_tracepoint/" and
> "tracepoint/", respectively. Any objections?
make sense.
>> If "name" is indeed a valid raw tracepoint then in-kernel BTF
>> will have "btf_trace_##name" typedef that points to function
>> prototype of that raw tracepoint. BTF description captures
>> exact argument the kernel C code is passing into raw tracepoint.
>> The kernel verifier will check the types while loading bpf program.
>>
>> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
>> ---
>> tools/lib/bpf/libbpf.c | 16 ++++++++++++++++
>> 1 file changed, 16 insertions(+)
>>
>> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
>> index e0276520171b..0e6f7b41c521 100644
>> --- a/tools/lib/bpf/libbpf.c
>> +++ b/tools/lib/bpf/libbpf.c
>> @@ -4591,6 +4591,22 @@ int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
>> continue;
>> *prog_type = section_names[i].prog_type;
>> *expected_attach_type = section_names[i].expected_attach_type;
>> + if (*prog_type == BPF_PROG_TYPE_RAW_TRACEPOINT) {
>> + struct btf *btf = bpf_core_find_kernel_btf();
>> + char raw_tp_btf_name[128] = "btf_trace_";
>> + int ret;
>> +
>> + if (IS_ERR(btf))
>> + /* lack of kernel BTF is not a failure */
>> + return 0;
>> + /* append "btf_trace_" prefix per kernel convention */
>> + strcpy(raw_tp_btf_name + sizeof("btf_trace_") - 1,
>> + name + section_names[i].len);
>
> buffer overflow here? use strncat() instead?
128 is ksym_name and due to tp construction with other prefixes,
I think, it cannot overflow, but that's a good nit. Fixed it.
next prev parent reply other threads:[~2019-10-09 2:27 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-05 5:03 [PATCH bpf-next 00/10] bpf: revolutionize bpf tracing Alexei Starovoitov
2019-10-05 5:03 ` [PATCH bpf-next 01/10] bpf: add typecast to raw_tracepoints to help BTF generation Alexei Starovoitov
2019-10-05 18:40 ` Andrii Nakryiko
2019-10-06 3:58 ` John Fastabend
2019-10-05 5:03 ` [PATCH bpf-next 02/10] bpf: add typecast to bpf helpers " Alexei Starovoitov
2019-10-05 18:41 ` Andrii Nakryiko
2019-10-06 4:00 ` John Fastabend
2019-10-05 5:03 ` [PATCH bpf-next 03/10] bpf: process in-kernel BTF Alexei Starovoitov
2019-10-06 6:36 ` Andrii Nakryiko
2019-10-06 23:49 ` Alexei Starovoitov
2019-10-07 0:20 ` Andrii Nakryiko
2019-10-09 20:51 ` Martin Lau
2019-10-10 3:43 ` Alexei Starovoitov
2019-10-05 5:03 ` [PATCH bpf-next 04/10] libbpf: auto-detect btf_id of raw_tracepoint Alexei Starovoitov
2019-10-07 23:41 ` Andrii Nakryiko
2019-10-09 2:26 ` Alexei Starovoitov [this message]
2019-10-05 5:03 ` [PATCH bpf-next 05/10] bpf: implement accurate raw_tp context access via BTF Alexei Starovoitov
2019-10-07 16:32 ` Alan Maguire
2019-10-09 3:59 ` Alexei Starovoitov
2019-10-08 0:35 ` Andrii Nakryiko
2019-10-09 3:30 ` Alexei Starovoitov
2019-10-09 4:01 ` Andrii Nakryiko
2019-10-09 5:10 ` Andrii Nakryiko
2019-10-10 3:54 ` Alexei Starovoitov
2019-10-05 5:03 ` [PATCH bpf-next 06/10] bpf: add support for BTF pointers to interpreter Alexei Starovoitov
2019-10-08 3:08 ` Andrii Nakryiko
2019-10-05 5:03 ` [PATCH bpf-next 07/10] bpf: add support for BTF pointers to x86 JIT Alexei Starovoitov
2019-10-05 6:03 ` Eric Dumazet
2019-10-09 17:38 ` Andrii Nakryiko
2019-10-09 17:46 ` Alexei Starovoitov
2019-10-05 5:03 ` [PATCH bpf-next 08/10] bpf: check types of arguments passed into helpers Alexei Starovoitov
2019-10-09 18:01 ` Andrii Nakryiko
2019-10-09 19:58 ` Alexei Starovoitov
2019-10-05 5:03 ` [PATCH bpf-next 09/10] bpf: disallow bpf_probe_read[_str] helpers Alexei Starovoitov
2019-10-09 5:29 ` Andrii Nakryiko
2019-10-09 19:38 ` Alexei Starovoitov
2019-10-05 5:03 ` [PATCH bpf-next 10/10] selftests/bpf: add kfree_skb raw_tp test Alexei Starovoitov
2019-10-09 5:36 ` Andrii Nakryiko
2019-10-09 17:37 ` Alexei Starovoitov
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