From: Eduard Zingerman <eddyz87@gmail.com>
To: Andrii Nakryiko <andrii@kernel.org>,
bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
martin.lau@kernel.org
Cc: kernel-team@meta.com, Dave Marchevsky <davemarchevsky@meta.com>
Subject: Re: [PATCH bpf-next 0/8] PTR_TO_BTF_ID arguments in global subprogs
Date: Mon, 08 Jan 2024 00:22:04 +0200 [thread overview]
Message-ID: <cb2d2a2e5f05e9aad0dfef1109fca9022b351e11.camel@gmail.com> (raw)
In-Reply-To: <20240105000909.2818934-1-andrii@kernel.org>
On Thu, 2024-01-04 at 16:09 -0800, Andrii Nakryiko wrote:
> This patch set follows recent changes that added btf_decl_tag-based argument
> annotation support for global subprogs. This time we add ability to pass
> PTR_TO_BTF_ID (BTF-aware kernel pointers) arguments into global subprograms.
> We support explicitly trusted and untrusted arguments. Legacy semi-trusted
> variant is not supported.
>
> Patches #2 through #4 do preparatory refactorings to add support for multiple
> tags per argument. This is important for being able to use modifiers like
> __arg_nonnull together with trusted/untrusted arguments.
>
> Patch #5 is adding the actual __arg_trusted and __arg_untrusted support.
>
> It also raises a question about default nullable vs non-nullable semantics for
> PTR_TO_BTF_ID arguments. It feels like having both __arg_nonnull and
> __arg_nullable would provide the best kind of experience and flexibility, but
> for now we implement nullable by default semantics, as a more conservative
> behavior.
>
> Patch #7 adds bpf_core_cast() helper macro which is a wrapper around
> bpf_rdonly_cast() kfunc, but hides BTF ID manipulations behind more
> user-friendly type argument instead. We utilize this macro in selftests added
> in patch #8.
>
> Patch #8 adds a bunch of positive and negative tests to validate expected
> semantics for various trusted/untrusted + nullable/non-null variants. We also
> make sure that global subprog cannot destroy PTR_TO_BTF_ID, as that would
> wreak havoc in caller program that is not aware of this possibility.
>
> There were proposals to do kernel-side type enforcement for __arg_ctx, let's
> decide whether we should do that and for which program types, and I can
> accommodate the logic in future revisions.
>
> Cc: Dave Marchevsky <davemarchevsky@meta.com>
Full patch-set looks good to me.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
next prev parent reply other threads:[~2024-01-07 22:22 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-05 0:09 [PATCH bpf-next 0/8] PTR_TO_BTF_ID arguments in global subprogs Andrii Nakryiko
2024-01-05 0:09 ` [PATCH bpf-next 1/8] selftests/bpf: fix test_loader check message Andrii Nakryiko
2024-01-05 0:09 ` [PATCH bpf-next 2/8] bpf: make sure scalar args don't accept __arg_nonnull tag Andrii Nakryiko
2024-01-05 0:09 ` [PATCH bpf-next 3/8] bpf: prepare btf_prepare_func_args() for multiple tags per argument Andrii Nakryiko
2024-01-05 0:09 ` [PATCH bpf-next 4/8] bpf: support " Andrii Nakryiko
2024-01-05 0:09 ` [PATCH bpf-next 5/8] bpf: add __arg_trusted and __arg_untrusted global func tags Andrii Nakryiko
2024-01-12 2:05 ` Alexei Starovoitov
2024-01-12 18:43 ` Andrii Nakryiko
2024-01-05 0:09 ` [PATCH bpf-next 6/8] libbpf: add __arg_trusted and __arg_untrusted annotation macros Andrii Nakryiko
2024-01-05 0:09 ` [PATCH bpf-next 7/8] libbpf: add bpf_core_cast() macro Andrii Nakryiko
2024-01-05 0:09 ` [PATCH bpf-next 8/8] selftests/bpf: add trusted/untrusted global subprog arg tests Andrii Nakryiko
2024-01-07 22:22 ` Eduard Zingerman [this message]
2024-01-12 2:40 ` [PATCH bpf-next 0/8] PTR_TO_BTF_ID arguments in global subprogs patchwork-bot+netdevbpf
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