linux-kernel - Re: [PATCH bpf-next v4 3/5] bpf: Add open coded dmabuf iterator

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAPhsuW613T4biUPER9zR9DdQA_wscN4-i3vV4efoOKUZ7pkTeA@mail.gmail.com>
Date: Thu, 8 May 2025 17:28:38 -0700
From: Song Liu <song@...nel.org>
To: "T.J. Mercier" <tjmercier@...gle.com>
Cc: sumit.semwal@...aro.org, christian.koenig@....com, ast@...nel.org, 
	daniel@...earbox.net, andrii@...nel.org, martin.lau@...ux.dev, 
	skhan@...uxfoundation.org, alexei.starovoitov@...il.com, 
	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org, 
	dri-devel@...ts.freedesktop.org, linaro-mm-sig@...ts.linaro.org, 
	bpf@...r.kernel.org, linux-kselftest@...r.kernel.org, android-mm@...gle.com, 
	simona@...ll.ch, eddyz87@...il.com, yonghong.song@...ux.dev, 
	john.fastabend@...il.com, kpsingh@...nel.org, sdf@...ichev.me, 
	jolsa@...nel.org, mykolal@...com, shuah@...nel.org
Subject: Re: [PATCH bpf-next v4 3/5] bpf: Add open coded dmabuf iterator

On Thu, May 8, 2025 at 11:20 AM T.J. Mercier <tjmercier@...gle.com> wrote:
>
> This open coded iterator allows for more flexibility when creating BPF
> programs. It can support output in formats other than text. With an open
> coded iterator, a single BPF program can traverse multiple kernel data
> structures (now including dmabufs), allowing for more efficient analysis
> of kernel data compared to multiple reads from procfs, sysfs, or
> multiple traditional BPF iterator invocations.
>
> Signed-off-by: T.J. Mercier <tjmercier@...gle.com>

Acked-by: Song Liu <song@...nel.org>

With one nitpick below:

> ---
>  kernel/bpf/dmabuf_iter.c | 47 ++++++++++++++++++++++++++++++++++++++++
>  kernel/bpf/helpers.c     |  5 +++++
>  2 files changed, 52 insertions(+)
>
> diff --git a/kernel/bpf/dmabuf_iter.c b/kernel/bpf/dmabuf_iter.c
> index 96b4ba7f0b2c..8049bdbc9efc 100644
> --- a/kernel/bpf/dmabuf_iter.c
> +++ b/kernel/bpf/dmabuf_iter.c
> @@ -100,3 +100,50 @@ static int __init dmabuf_iter_init(void)
>  }
>
>  late_initcall(dmabuf_iter_init);
> +
> +struct bpf_iter_dmabuf {
> +       /* opaque iterator state; having __u64 here allows to preserve correct
> +        * alignment requirements in vmlinux.h, generated from BTF
> +        */

nit: comment style.

> +       __u64 __opaque[1];
> +} __aligned(8);
> +
> +/* Non-opaque version of bpf_iter_dmabuf */
> +struct bpf_iter_dmabuf_kern {
> +       struct dma_buf *dmabuf;
> +} __aligned(8);
> +
[...]