From: Eduard Zingerman <eddyz87@gmail.com>
To: Viktor Malik <vmalik@redhat.com>, bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>,
Stanislav Fomichev <sdf@fomichev.me>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>
Subject: Re: [PATCH bpf-next v2 0/2] bpf: Add kfuncs for read-only string operations
Date: Thu, 26 Sep 2024 18:37:07 -0700 [thread overview]
Message-ID: <efa0ba9ce828010cd6fea1efa45b17c1b0800ace.camel@gmail.com> (raw)
In-Reply-To: <cover.1727335530.git.vmalik@redhat.com>
On Thu, 2024-09-26 at 09:29 +0200, Viktor Malik wrote:
> Kernel contains highly optimised implementation of traditional string
> operations. Expose them as kfuncs to allow BPF programs leverage the
> kernel implementation instead of needing to reimplement the operations.
>
> These will be very helpful to bpftrace as it now needs to implement all
> the string operations in LLVM IR.
Note that existing string related helpers take a pointer to a string
and it's maximal length, namely:
- bpf_strtol
- bpf_strtoul
- bpf_snprintf_btf
- bpf_strncmp
The unbounded variants that are being exposed in this patch-set
(like strcmp) are only safe to use if string is guaranteed to be null terminated.
Verifier does not check this property at the moment (idk how easy/hard
such analysis might be).
I'd suggest not to expose unbounded variants of string functions.
[...]
next prev parent reply other threads:[~2024-09-27 1:37 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-26 7:29 [PATCH bpf-next v2 0/2] bpf: Add kfuncs for read-only string operations Viktor Malik
2024-09-26 7:29 ` [PATCH bpf-next v2 1/2] " Viktor Malik
2024-09-26 7:29 ` [PATCH bpf-next v2 2/2] selftests/bpf: Add tests for string kfuncs Viktor Malik
2024-09-27 1:57 ` Eduard Zingerman
2024-09-27 7:20 ` Viktor Malik
2024-09-27 1:37 ` Eduard Zingerman [this message]
2024-09-27 7:12 ` [PATCH bpf-next v2 0/2] bpf: Add kfuncs for read-only string operations Viktor Malik
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