From: Kees Cook <keescook@chromium.org>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
Stanislav Fomichev <sdf@google.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>, Hao Luo <haoluo@google.com>,
Jiri Olsa <jolsa@kernel.org>, Mykola Lysenko <mykolal@fb.com>,
Shuah Khan <shuah@kernel.org>, Haowen Bai <baihaowen@meizu.com>,
bpf@vger.kernel.org, linux-kselftest@vger.kernel.org,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Jesper Dangaard Brouer <hawk@kernel.org>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Tom Rix <trix@redhat.com>,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
llvm@lists.linux.dev, linux-hardening@vger.kernel.org
Subject: Re: [PATCH] bpf: Deprecate "data" member of bpf_lpm_trie_key
Date: Thu, 9 Feb 2023 12:05:45 -0800 [thread overview]
Message-ID: <63e5521a.170a0220.297d7.3a80@mx.google.com> (raw)
In-Reply-To: <CAEf4BzZXrf48wsTP=2H2gkX6T+MM0B45o0WNswi50DQ_B-WG4Q@mail.gmail.com>
On Thu, Feb 09, 2023 at 11:52:10AM -0800, Andrii Nakryiko wrote:
> Do we need to add a new type to UAPI at all here? We can make this new
> struct internal to kernel code (e.g. struct bpf_lpm_trie_key_kern) and
> point out that it should match the layout of struct bpf_lpm_trie_key.
> User-space can decide whether to use bpf_lpm_trie_key as-is, or if
> just to ensure their custom struct has the same layout (I see some
> internal users at Meta do just this, just make sure that they have
> __u32 prefixlen as first member).
The uses outside the kernel seemed numerous enough to justify a new UAPI
struct (samples, selftests, etc). It also paves a single way forward
when the userspace projects start using modern compiler options (e.g.
systemd is usually pretty quick to adopt new features).
> This whole union work-around seems like just extra cruft that we don't
> really need in UAPI.
The union is really only there so that possible uses of container_of()
would be happy. But I did add a BUILD_BUG_ON() test for member offset
equality, so a hard cast would be safe too. I'm happy to drop it if
that's preferred?
--
Kees Cook
next prev parent reply other threads:[~2023-02-09 20:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-09 19:23 [PATCH] bpf: Deprecate "data" member of bpf_lpm_trie_key Kees Cook
2023-02-09 19:52 ` Andrii Nakryiko
2023-02-09 20:05 ` Kees Cook [this message]
2023-02-09 20:50 ` Alexei Starovoitov
2023-02-09 21:12 ` Kees Cook
2023-02-09 22:01 ` Alexei Starovoitov
2023-02-11 17:55 ` Kees Cook
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