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
Subject: Re: [PATCH v2 bpf-next 07/10] bpf: add support for passing dynptr pointer to global subprog
Date: Wed, 13 Dec 2023 19:43:25 +0200 [thread overview]
Message-ID: <1c6862c290c555c900e34ff0552a37f5779886e0.camel@gmail.com> (raw)
In-Reply-To: <20231212232535.1875938-8-andrii@kernel.org>
On Tue, 2023-12-12 at 15:25 -0800, Andrii Nakryiko wrote:
> Add ability to pass a pointer to dynptr into global functions.
> This allows to have global subprogs that accept and work with generic
> dynptrs that are created by caller. Dynptr argument is detected based on
> the name of a struct type, if it's "bpf_dynptr", it's assumed to be
> a proper dynptr pointer. Both actual struct and forward struct
> declaration types are supported.
>
> This is conceptually exactly the same semantics as
> bpf_user_ringbuf_drain()'s use of dynptr to pass a variable-sized
> pointer to ringbuf record. So we heavily rely on CONST_PTR_TO_DYNPTR
> bits of already existing logic in the verifier.
>
> During global subprog validation, we mark such CONST_PTR_TO_DYNPTR as
> having LOCAL type, as that's the most unassuming type of dynptr and it
> doesn't have any special helpers that can try to free or acquire extra
> references (unlike skb, xdp, or ringbuf dynptr). So that seems like a safe
> "choice" to make from correctness standpoint. It's still possible to
> pass any type of dynptr to such subprog, though, because generic dynptr
> helpers, like getting data/slice pointers, read/write memory copying
> routines, dynptr adjustment and getter routines all work correctly with
> any type of dynptr.
>
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
> ---
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
next prev parent reply other threads:[~2023-12-13 17:43 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-12 23:25 [PATCH v2 bpf-next 00/10] Enhance BPF global subprogs with argument tags Andrii Nakryiko
2023-12-12 23:25 ` [PATCH v2 bpf-next 01/10] bpf: abstract away global subprog arg preparation logic from reg state setup Andrii Nakryiko
2023-12-12 23:25 ` [PATCH v2 bpf-next 02/10] bpf: reuse btf_prepare_func_args() check for main program BTF validation Andrii Nakryiko
2023-12-13 17:43 ` Eduard Zingerman
2023-12-13 18:06 ` Andrii Nakryiko
2023-12-13 18:14 ` Eduard Zingerman
2023-12-13 18:23 ` Andrii Nakryiko
2023-12-13 18:29 ` Eduard Zingerman
2023-12-12 23:25 ` [PATCH v2 bpf-next 03/10] bpf: prepare btf_prepare_func_args() for handling static subprogs Andrii Nakryiko
2023-12-12 23:25 ` [PATCH v2 bpf-next 04/10] bpf: move subprog call logic back to verifier.c Andrii Nakryiko
2023-12-12 23:25 ` [PATCH v2 bpf-next 05/10] bpf: reuse subprog argument parsing logic for subprog call checks Andrii Nakryiko
2023-12-12 23:25 ` [PATCH v2 bpf-next 06/10] bpf: support 'arg:xxx' btf_decl_tag-based hints for global subprog args Andrii Nakryiko
2023-12-13 17:43 ` Eduard Zingerman
2023-12-13 19:18 ` Andrii Nakryiko
2023-12-13 19:33 ` Eduard Zingerman
2023-12-12 23:25 ` [PATCH v2 bpf-next 07/10] bpf: add support for passing dynptr pointer to global subprog Andrii Nakryiko
2023-12-13 17:43 ` Eduard Zingerman [this message]
2023-12-12 23:25 ` [PATCH v2 bpf-next 08/10] libbpf: add __arg_xxx macros for annotating global func args Andrii Nakryiko
2023-12-13 17:43 ` Eduard Zingerman
2023-12-12 23:25 ` [PATCH v2 bpf-next 09/10] selftests/bpf: add global subprog annotation tests Andrii Nakryiko
2023-12-12 23:25 ` [PATCH v2 bpf-next 10/10] selftests/bpf: add freplace of BTF-unreliable main prog test Andrii Nakryiko
2023-12-13 17:44 ` Eduard Zingerman
2023-12-13 19:25 ` Andrii Nakryiko
2023-12-13 20:39 ` Eduard Zingerman
2023-12-13 22:48 ` Andrii Nakryiko
2023-12-14 0:14 ` Eduard Zingerman
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