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Wed, 24 Jan 2024 00:58:37 -0800 (PST) From: Liang Chen To: mst@redhat.com, jasowang@redhat.com, hengqi@linux.alibaba.com, xuanzhuo@linux.alibaba.com Cc: virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, liangchen.linux@gmail.com Subject: [PATCH v2 1/3] virtio_net: Preserve virtio header before XDP program execution Date: Wed, 24 Jan 2024 16:57:19 +0800 Message-Id: <20240124085721.54442-2-liangchen.linux@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240124085721.54442-1-liangchen.linux@gmail.com> References: <20240124085721.54442-1-liangchen.linux@gmail.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The xdp program may overwrite the inline virtio header. To ensure the integrity of the virtio header, it is saved in a data structure that wraps both the xdp_buff and the header before running the xdp program. Signed-off-by: Liang Chen --- drivers/net/virtio_net.c | 43 +++++++++++++++++++++++++++++----------- 1 file changed, 31 insertions(+), 12 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index d7ce4a1011ea..b56828804e5f 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -349,6 +349,11 @@ struct virtio_net_common_hdr { }; }; +struct virtnet_xdp_buff { + struct xdp_buff xdp; + struct virtio_net_common_hdr hdr; +}; + static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf); static bool is_xdp_frame(void *ptr) @@ -1199,9 +1204,10 @@ static struct sk_buff *receive_small_xdp(struct net_device *dev, unsigned int headroom = vi->hdr_len + header_offset; struct virtio_net_hdr_mrg_rxbuf *hdr = buf + header_offset; struct page *page = virt_to_head_page(buf); + struct virtnet_xdp_buff virtnet_xdp; struct page *xdp_page; + struct xdp_buff *xdp; unsigned int buflen; - struct xdp_buff xdp; struct sk_buff *skb; unsigned int metasize = 0; u32 act; @@ -1233,17 +1239,23 @@ static struct sk_buff *receive_small_xdp(struct net_device *dev, page = xdp_page; } - xdp_init_buff(&xdp, buflen, &rq->xdp_rxq); - xdp_prepare_buff(&xdp, buf + VIRTNET_RX_PAD + vi->hdr_len, + xdp = &virtnet_xdp.xdp; + xdp_init_buff(xdp, buflen, &rq->xdp_rxq); + xdp_prepare_buff(xdp, buf + VIRTNET_RX_PAD + vi->hdr_len, xdp_headroom, len, true); - act = virtnet_xdp_handler(xdp_prog, &xdp, dev, xdp_xmit, stats); + /* Copy out the virtio header, as it may be overwritten by the + * xdp program. + */ + memcpy(&virtnet_xdp.hdr, hdr, vi->hdr_len); + + act = virtnet_xdp_handler(xdp_prog, xdp, dev, xdp_xmit, stats); switch (act) { case XDP_PASS: /* Recalculate length in case bpf program changed it */ - len = xdp.data_end - xdp.data; - metasize = xdp.data - xdp.data_meta; + len = xdp->data_end - xdp->data; + metasize = xdp->data - xdp->data_meta; break; case XDP_TX: @@ -1254,7 +1266,7 @@ static struct sk_buff *receive_small_xdp(struct net_device *dev, goto err_xdp; } - skb = virtnet_build_skb(buf, buflen, xdp.data - buf, len); + skb = virtnet_build_skb(buf, buflen, xdp->data - buf, len); if (unlikely(!skb)) goto err; @@ -1591,10 +1603,11 @@ static struct sk_buff *receive_mergeable_xdp(struct net_device *dev, int num_buf = virtio16_to_cpu(vi->vdev, hdr->num_buffers); struct page *page = virt_to_head_page(buf); int offset = buf - page_address(page); + struct virtnet_xdp_buff virtnet_xdp; unsigned int xdp_frags_truesz = 0; struct sk_buff *head_skb; unsigned int frame_sz; - struct xdp_buff xdp; + struct xdp_buff *xdp; void *data; u32 act; int err; @@ -1604,16 +1617,22 @@ static struct sk_buff *receive_mergeable_xdp(struct net_device *dev, if (unlikely(!data)) goto err_xdp; - err = virtnet_build_xdp_buff_mrg(dev, vi, rq, &xdp, data, len, frame_sz, + xdp = &virtnet_xdp.xdp; + err = virtnet_build_xdp_buff_mrg(dev, vi, rq, xdp, data, len, frame_sz, &num_buf, &xdp_frags_truesz, stats); if (unlikely(err)) goto err_xdp; - act = virtnet_xdp_handler(xdp_prog, &xdp, dev, xdp_xmit, stats); + /* Copy out the virtio header, as it may be overwritten by the + * xdp program. + */ + memcpy(&virtnet_xdp.hdr, hdr, vi->hdr_len); + + act = virtnet_xdp_handler(xdp_prog, xdp, dev, xdp_xmit, stats); switch (act) { case XDP_PASS: - head_skb = build_skb_from_xdp_buff(dev, vi, &xdp, xdp_frags_truesz); + head_skb = build_skb_from_xdp_buff(dev, vi, xdp, xdp_frags_truesz); if (unlikely(!head_skb)) break; return head_skb; @@ -1626,7 +1645,7 @@ static struct sk_buff *receive_mergeable_xdp(struct net_device *dev, break; } - put_xdp_frags(&xdp); + put_xdp_frags(xdp); err_xdp: put_page(page); -- 2.40.1