From patchwork Mon Feb 17 17:23:04 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marcus Wichelmann X-Patchwork-Id: 13978392 Received: from dediextern.your-server.de (dediextern.your-server.de [85.10.215.232]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 11F5322A80F; Mon, 17 Feb 2025 17:39:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=85.10.215.232 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739813980; cv=none; b=W6l8JUDZ9PxIblUxfvmn03D6Nq4AkbCaHmHLjpp1ghFi/jBdpmKLepMxufmJknHotLj1qZZ+tetd80FhWmDnzVGLVHwGfJgj51ephJ/WsCeGejTtshjgG6bp2SW/3xhpGnMU7V4r4Uxy6mbN7w9jljND3TVWAsXGSkecEAT5WmY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739813980; c=relaxed/simple; bh=Bvo5A+HxVYkofD15X8SIOEKYTgZnOA+GsBJaJ9I6fno=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LmbkpGgj/GmLEIawDfoUeBwUPfeoN8UuoPIpB5hh09CvXqIWa/H/c1AtOVWMsCnNJEgz3QvYpFl/jAf6la/El62ypzFd/vZ5UusrXkQ1llip2EyUoxg0COSVoQ1GlMBNLGboTOLUa7FRTMExwS7AOrkBJUavaXEDyV8wQkiQ4xk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=hetzner-cloud.de; spf=pass smtp.mailfrom=hetzner-cloud.de; arc=none smtp.client-ip=85.10.215.232 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=hetzner-cloud.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=hetzner-cloud.de Received: from sslproxy01.your-server.de ([78.46.139.224]) by dediextern.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1tk4pt-0001wi-QQ; Mon, 17 Feb 2025 18:23:13 +0100 Received: from [78.47.5.107] (helo=sdn-nic-test01..) by sslproxy01.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1tk4pt-000Opa-1c; Mon, 17 Feb 2025 18:23:13 +0100 From: Marcus Wichelmann To: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: willemdebruijn.kernel@gmail.com, jasowang@redhat.com, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, mykolal@fb.com, shuah@kernel.org, hawk@kernel.org, marcus.wichelmann@hetzner-cloud.de Subject: [PATCH bpf-next v2 2/6] net: tun: enable transfer of XDP metadata to skb Date: Mon, 17 Feb 2025 17:23:04 +0000 Message-ID: <20250217172308.3291739-3-marcus.wichelmann@hetzner-cloud.de> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250217172308.3291739-1-marcus.wichelmann@hetzner-cloud.de> References: <20250217172308.3291739-1-marcus.wichelmann@hetzner-cloud.de> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Authenticated-Sender: marcus.wichelmann@hetzner-cloud.de X-Virus-Scanned: Clear (ClamAV 1.0.7/27552/Mon Feb 17 10:47:21 2025) When the XDP metadata area was used, it is expected that the same metadata can also be accessed from TC, as can be read in the description of the bpf_xdp_adjust_meta helper function. In the tun driver, this was not yet implemented. To make this work, the skb that is being built on XDP_PASS should know of the current size of the metadata area. This is ensured by adding calls to skb_metadata_set. For the tun_xdp_one code path, an additional check is necessary to handle the case where the externally initialized xdp_buff has no metadata support (xdp->data_meta == xdp->data + 1). More information about this feature can be found in the commit message of commit de8f3a83b0a0 ("bpf: add meta pointer for direct access"). Signed-off-by: Marcus Wichelmann --- drivers/net/tun.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index c95ab9c46bd2..3dde6cd29a84 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1604,7 +1604,8 @@ static bool tun_can_build_skb(struct tun_struct *tun, struct tun_file *tfile, static struct sk_buff *__tun_build_skb(struct tun_file *tfile, struct page_frag *alloc_frag, char *buf, - int buflen, int len, int pad) + int buflen, int len, int pad, + int metasize) { struct sk_buff *skb = build_skb(buf, buflen); @@ -1613,6 +1614,8 @@ static struct sk_buff *__tun_build_skb(struct tun_file *tfile, skb_reserve(skb, pad); skb_put(skb, len); + if (metasize) + skb_metadata_set(skb, metasize); skb_set_owner_w(skb, tfile->socket.sk); get_page(alloc_frag->page); @@ -1672,6 +1675,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, char *buf; size_t copied; int pad = TUN_RX_PAD; + int metasize = 0; int err = 0; rcu_read_lock(); @@ -1699,7 +1703,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, if (hdr->gso_type || !xdp_prog) { *skb_xdp = 1; return __tun_build_skb(tfile, alloc_frag, buf, buflen, len, - pad); + pad, metasize); } *skb_xdp = 0; @@ -1734,12 +1738,18 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, pad = xdp.data - xdp.data_hard_start; len = xdp.data_end - xdp.data; + + /* It is known that the xdp_buff was prepared with metadata + * support, so no additional check is necessary. + */ + metasize = xdp.data - xdp.data_meta; } bpf_net_ctx_clear(bpf_net_ctx); rcu_read_unlock(); local_bh_enable(); - return __tun_build_skb(tfile, alloc_frag, buf, buflen, len, pad); + return __tun_build_skb(tfile, alloc_frag, buf, buflen, len, pad, + metasize); out: bpf_net_ctx_clear(bpf_net_ctx); @@ -2456,6 +2466,7 @@ static int tun_xdp_one(struct tun_struct *tun, struct sk_buff_head *queue; u32 rxhash = 0, act; int buflen = hdr->buflen; + int metasize = 0; int ret = 0; bool skb_xdp = false; struct page *page; @@ -2510,6 +2521,10 @@ static int tun_xdp_one(struct tun_struct *tun, skb_reserve(skb, xdp->data - xdp->data_hard_start); skb_put(skb, xdp->data_end - xdp->data); + metasize = max(xdp->data - xdp->data_meta, 0); + if (metasize) + skb_metadata_set(skb, metasize); + if (virtio_net_hdr_to_skb(skb, gso, tun_is_little_endian(tun))) { atomic_long_inc(&tun->rx_frame_errors); kfree_skb(skb);