From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 973FDC433F5 for ; Fri, 4 Mar 2022 18:41:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241800AbiCDSmP (ORCPT ); Fri, 4 Mar 2022 13:42:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51054 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231818AbiCDSmG (ORCPT ); Fri, 4 Mar 2022 13:42:06 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 717951C887D; Fri, 4 Mar 2022 10:41:18 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 24488B82AB6; Fri, 4 Mar 2022 18:41:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A04BC340E9; Fri, 4 Mar 2022 18:41:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1646419275; bh=uxk8jrltaI2bVraUdYKTkU9k+XFyK/OnzyDp1sbSgVs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=sUcs4WgIH6R+ZZEPQK4UoiWMqAYIJXAgGfqZAYzJonteRITY92L2DwiOF7rRyQlBD 1Be95H+zW+ls6ErzlcclmLSqlGkxyNnGFyzfUrue1pFJDJRfHNJXSoPH4Y+A6Ikhyf 7+O0Lpanus/sCgGHDKahstBt0GzMjFzZc2zlHvz8= Date: Fri, 4 Mar 2022 19:41:09 +0100 From: Greg KH To: Benjamin Tissoires Cc: Jiri Kosina , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Shuah Khan , Dave Marchevsky , Joe Stringer , Tero Kristo , linux-kernel@vger.kernel.org, linux-input@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH bpf-next v2 12/28] bpf/hid: add hid_{get|set}_data helpers Message-ID: References: <20220304172852.274126-1-benjamin.tissoires@redhat.com> <20220304172852.274126-13-benjamin.tissoires@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220304172852.274126-13-benjamin.tissoires@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 04, 2022 at 06:28:36PM +0100, Benjamin Tissoires wrote: > When we process an incoming HID report, it is common to have to account > for fields that are not aligned in the report. HID is using 2 helpers > hid_field_extract() and implement() to pick up any data at any offset > within the report. > > Export those 2 helpers in BPF programs so users can also rely on them. > The second net worth advantage of those helpers is that now we can > fetch data anywhere in the report without knowing at compile time the > location of it. The boundary checks are done in hid-bpf.c, to prevent > a memory leak. > > Signed-off-by: Benjamin Tissoires > > --- > > changes in v2: > - split the patch with libbpf and HID left outside. > --- > include/linux/bpf-hid.h | 4 +++ > include/uapi/linux/bpf.h | 32 ++++++++++++++++++++ > kernel/bpf/hid.c | 53 ++++++++++++++++++++++++++++++++++ > tools/include/uapi/linux/bpf.h | 32 ++++++++++++++++++++ > 4 files changed, 121 insertions(+) > > diff --git a/include/linux/bpf-hid.h b/include/linux/bpf-hid.h > index 0c5000b28b20..69bb28523ceb 100644 > --- a/include/linux/bpf-hid.h > +++ b/include/linux/bpf-hid.h > @@ -93,6 +93,10 @@ struct bpf_hid_hooks { > int (*link_attach)(struct hid_device *hdev, enum bpf_hid_attach_type type); > void (*link_attached)(struct hid_device *hdev, enum bpf_hid_attach_type type); > void (*array_detached)(struct hid_device *hdev, enum bpf_hid_attach_type type); > + int (*hid_get_data)(struct hid_device *hdev, u8 *buf, size_t buf_size, > + u64 offset, u32 n, u8 *data, u64 data_size); > + int (*hid_set_data)(struct hid_device *hdev, u8 *buf, size_t buf_size, > + u64 offset, u32 n, u8 *data, u64 data_size); > }; > > #ifdef CONFIG_BPF > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > index a7a8d9cfcf24..4845a20e6f96 100644 > --- a/include/uapi/linux/bpf.h > +++ b/include/uapi/linux/bpf.h > @@ -5090,6 +5090,36 @@ union bpf_attr { > * Return > * 0 on success, or a negative error in case of failure. On error > * *dst* buffer is zeroed out. > + * > + * int bpf_hid_get_data(void *ctx, u64 offset, u32 n, u8 *data, u64 size) > + * Description > + * Get the data of size n (in bits) at the given offset (bits) in the > + * ctx->event.data field and store it into data. > + * > + * if n is less or equal than 32, we can address with bit precision, > + * the value in the buffer. However, data must be a pointer to a u32 > + * and size must be 4. > + * > + * if n is greater than 32, offset and n must be a multiple of 8 > + * and the result is working with a memcpy internally. > + * Return > + * The length of data copied into data. On error, a negative value > + * is returned. > + * > + * int bpf_hid_set_data(void *ctx, u64 offset, u32 n, u8 *data, u64 size) > + * Description > + * Set the data of size n (in bits) at the given offset (bits) in the > + * ctx->event.data field. > + * > + * if n is less or equal than 32, we can address with bit precision, > + * the value in the buffer. However, data must be a pointer to a u32 > + * and size must be 4. > + * > + * if n is greater than 32, offset and n must be a multiple of 8 > + * and the result is working with a memcpy internally. > + * Return > + * The length of data copied into ctx->event.data. On error, a negative > + * value is returned. Wait, nevermind my reviewed-by previously, see my comment about how this might be split into 4: bpf_hid_set_bytes() bpf_hid_get_bytes() bpf_hid_set_bits() bpf_hid_get_bits() Should be easier to understand and maintain over time, right? thanks, greg k-h