From: Lorenz Bauer <lmb@isovalent.com>
To: Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
martin.lau@kernel.org, timo@incline.eu,
robin.goegge@isovalent.com, kernel-team@meta.com
Subject: Re: [PATCH v2 bpf-next 2/6] bpf: remove minimum size restrictions on verifier log buffer
Date: Thu, 30 Mar 2023 18:12:34 +0100 [thread overview]
Message-ID: <CAN+4W8gsHdFd8BgjyndvpabZ-m3tNohU8LhQwT=yv+wi6NKvXw@mail.gmail.com> (raw)
In-Reply-To: <20230328235610.3159943-3-andrii@kernel.org>
On Wed, Mar 29, 2023 at 12:56 AM Andrii Nakryiko <andrii@kernel.org> wrote:
>
> It's not clear why we have 128 as minimum size, but it makes testing
> harder and seems unnecessary, as we carefully handle truncation
> scenarios and use proper snprintf variants. So remove this limitation
> and just enfore positive length for log buffer.
Nit: enforce
>
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Lorenz Bauer <lmb@isovalent.com>
> ---
> kernel/bpf/log.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/log.c b/kernel/bpf/log.c
> index 920061e38d2e..1974891fc324 100644
> --- a/kernel/bpf/log.c
> +++ b/kernel/bpf/log.c
> @@ -11,7 +11,7 @@
>
> bool bpf_verifier_log_attr_valid(const struct bpf_verifier_log *log)
> {
> - return log->len_total >= 128 && log->len_total <= UINT_MAX >> 2 &&
> + return log->len_total > 0 && log->len_total <= UINT_MAX >> 2 &&
> log->level && log->ubuf && !(log->level & ~BPF_LOG_MASK);
Probably discussion for your second series. Thought experiment, could
this be len_total >= 0? I'm still after a way to get the correct log
buffer size from the first PROG_LOAD call. If the kernel could handle
this I could mmap a PROT_NONE page, set len_total to 0 and later read
out the correct buffer size.
I'm guessing that the null termination logic would have to be
adjusted, anything else though?
next prev parent reply other threads:[~2023-03-30 17:12 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-28 23:56 [PATCH v2 bpf-next 0/6] BPF verifier rotating log Andrii Nakryiko
2023-03-28 23:56 ` [PATCH v2 bpf-next 1/6] bpf: split off basic BPF verifier log into separate file Andrii Nakryiko
2023-03-30 17:12 ` Lorenz Bauer
2023-03-28 23:56 ` [PATCH v2 bpf-next 2/6] bpf: remove minimum size restrictions on verifier log buffer Andrii Nakryiko
2023-03-30 17:12 ` Lorenz Bauer [this message]
2023-03-30 20:48 ` Andrii Nakryiko
2023-03-28 23:56 ` [PATCH v2 bpf-next 3/6] bpf: switch BPF verifier log to be a rotating log by default Andrii Nakryiko
2023-03-30 17:12 ` Lorenz Bauer
2023-03-30 20:48 ` Andrii Nakryiko
2023-04-05 17:29 ` Lorenz Bauer
2023-04-05 18:03 ` Andrii Nakryiko
2023-03-28 23:56 ` [PATCH v2 bpf-next 4/6] libbpf: don't enforce verifier log levels on libbpf side Andrii Nakryiko
2023-03-30 17:12 ` Lorenz Bauer
2023-03-30 21:05 ` Andrii Nakryiko
2023-03-31 9:39 ` Timo Beckers
2023-03-31 15:59 ` Andrii Nakryiko
2023-03-28 23:56 ` [PATCH bpf-next 4/6] libbpf: don't enfore " Andrii Nakryiko
2023-03-28 23:56 ` [PATCH v2 bpf-next 5/6] selftests/bpf: add more veristat control over verifier log options Andrii Nakryiko
2023-03-28 23:56 ` [PATCH v2 bpf-next 6/6] selftests/bpf: add fixed vs rotating verifier log tests Andrii Nakryiko
2023-03-30 17:12 ` Lorenz Bauer
2023-03-30 21:07 ` Andrii Nakryiko
2023-03-28 23:59 ` [PATCH v2 bpf-next 0/6] BPF verifier rotating log Andrii Nakryiko
2023-03-30 5:38 ` Alexei Starovoitov
2023-03-30 9:31 ` Lorenz Bauer
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