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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EE0A5C982ED for ; Mon, 21 Sep 2026 02:53:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=fkhGS8LwLr9AchoqrwEQvfmCs6eRJO1/8RM9quRrKBU=; b=uykFJGEh1MCVOZih/i+esffcBh pJtzcGxnGrNtgntOQUxDHq/ZRzanrCfG2esyiVnj7agA+Rex4New+kykRF6ZRTclOq+aoNwz/uZSH wMQnEfTW+9QL+8a28cMqj9+UTavTHkoNPGnuEJfXKkvSLiHdSwMmsIv4i8hgOa6P8wfJjZmFbo39r MyxYcMf3NUvyrhzwj5wa2FN7jSMiEVphXl6sDlEaTGlFTPuRKYdmAzLtZIGtdjx+CHPpd3a0ply6J 10wGwQ2iH3mgY32zZ8FXiTvboRBF7EbxuzSRdYrfWobvjtfUHchGYGggY4tRRuLtWR909jgQL8Qkd 7alsTG5Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x8UAE-00000000kMw-02HB; Mon, 21 Sep 2026 02:53:54 +0000 Received: from mail-qk2-x10.google.com ([2607:f8b0:4864:34::10]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x8UAB-00000000kM8-1qfS for linux-um@lists.infradead.org; Mon, 21 Sep 2026 02:53:52 +0000 Received: by mail-qk2-x10.google.com with SMTP id af79cd13be357-939ca12ab70so317943985a.1 for ; Sun, 20 Sep 2026 19:53:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1789959230; x=1790564030; darn=lists.infradead.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=fkhGS8LwLr9AchoqrwEQvfmCs6eRJO1/8RM9quRrKBU=; b=ngGEstwvSAIBJ/Wf//FvwApUXbUDxAYiaNuHEq1w0mGVL3xtIFyKlPTH1xmgTfNc// q8e0HANzgwRFZtKSqekh7kiD4ZIan5BwSu1XW/PgFTOK4um8pYAOL61IXQgKoIM5OhN8 UO23tS1pARLq0Q7nfNwMdHZx81+lsFEogRGww/oTYMF2W7yVy8YMdXwWb8O6Ng5Uwltj lDFSvTQQ3AeGs201mt1XLUFrTfRmpIrvBlgfGRCc+qetGZFU3puHtWXBfmxodrm4pIZh kOdqvcJUIdiU+epoLRbtZGBTrdZ1/1BuBGE4PfkvXQZpPWec96S4JujMcg0MOoysaR4v w6CA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1789959230; x=1790564030; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=fkhGS8LwLr9AchoqrwEQvfmCs6eRJO1/8RM9quRrKBU=; b=E44f0wGVlVSUGEfVXCsHRP+9b/GDYA8OUM6O/VWT+oynakWOHdi8zX3G8rdkaoRO/4 D7/qVOZ7NYWs0X3hf6X+ZFVYKQDtxUYC8Gc04udH7BD3Tu5m4d09A7HaFMESRaFZXpz/ sOcASDqk/xFtTQ9OWXXDxH5PKpmXL9nUcsz0xu49qQUlYoDj9TcGEdLYFlrvjVFAs5ts umC/QfbMz54uEF/XpcQGjzvqNUm6IO3pjEspkqXhYW5ZTBqoHdk4pci4NIni9G9RIZDr yvEFSftyyjUjiWLV6MqZ6n8kxEkWEzvZThqlijh2ipZ+QgvXU112gc1HoEzdONBYVvfG EwVg== X-Forwarded-Encrypted: i=1; AKwUvBxhusCn9bG2r186sXApb3rWD1SdfxV7PCO76GPjSpS3Za111SvRd0zAkoK8b5BP5KWzcoLbGL/hJg==@lists.infradead.org X-Gm-Message-State: AFuF++nx6v74SKJmhlMVTIU7eBn+cc8xtl8AknJTi0FxbAdvRqiNXoHk khUqQNsKCP3x97RCVXzWxO6LzVyDKf23wGn1i9BWFHAAVIc6kd6ovJJL X-Gm-Gg: AYBFou0OVd88jmIc0Q2gQQh59Kaq5tQEcKOfuW3H/1yV0vpA4RlVkm178GyK3EX2eax 0fU4yN7FSbbx6LFaHqoLR8ElS3NjGspqiVJyCjhTfXwicD0lzR/mZQiUhXFtCaJnva8wYyZyssk 1ARZqHaDRmUaUyNiHOtSsPWtAymX3H4bKL7X+ynpjxNzLr41teqB6gY66Ps9MJgVdd8FZypItDx ybfr9oX9O6BJHrQE92TGT4BOts7mr694r7BG2bFC6oNf7Trjg7dW3cxtZzqALpIQBcyib+jZaz/ 231Sew3aQXDQS4hfiHkgxRlCwrFwxKHahayJGe5anBxJFiTrCPyMLly5vcKDKcM7YE3zQhsCxnE pwOCB8oPYKE8jEk760/AApZf9DFpJquWpIJf2EVovU8m7fOCDCMWXJHAlw4EvdYHA9j/JREOJai U6quv4zKeLin1xY8KOWK/A34r3j3dnIJyf4AE+n5fLHZ3wVxuuyy+/OHnhedFowJD3a0kmJf227 jEjRVDzbOwRpBljbXV4ALiZyaDrPsj/xxKOyAfGDGCHFj5rOUNssYmTOdj81X4E/sSrTOyU X-Received: by 2002:a05:620a:298c:b0:93b:d7a1:ba0b with SMTP id af79cd13be357-93bf5742f73mr878321485a.54.1789959230321; Sun, 20 Sep 2026 19:53:50 -0700 (PDT) Received: from localhost.localdomain ([2601:155:4200:2c80:64b9:5e22:f77c:324e]) by smtp.gmail.com with ESMTPSA id af79cd13be357-93bedb3de58sm528732785a.37.2026.09.20.19.53.48 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Sun, 20 Sep 2026 19:53:49 -0700 (PDT) From: Paulos Yibelo To: netdev@vger.kernel.org Cc: richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net, willemdebruijn.kernel@gmail.com, jasowangio@gmail.com, mst@redhat.com, eperezma@redhat.com, xuanzhuo@linux.alibaba.com, andrew+netdev@lunn.ch, pablo@netfilter.org, fw@strlen.de, phil@nwl.cc, razor@blackwall.org, idosch@nvidia.com, dsahern@kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, linux-um@lists.infradead.org, virtualization@lists.linux.dev, netfilter-devel@vger.kernel.org, coreteam@netfilter.org, bridge@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH net v5 1/2] net: validate virtio checksum start after network header Date: Sun, 20 Sep 2026 22:53:40 -0400 Message-ID: <20260921025341.44846-2-habte.yibelo@gmail.com> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20260921025341.44846-1-habte.yibelo@gmail.com> References: <20260920004733.6473-1-habte.yibelo@gmail.com> <20260921025341.44846-1-habte.yibelo@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260920_195351_510710_12C57992 X-CRM114-Status: GOOD ( 23.54 ) X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org __virtio_net_hdr_to_skb() rejects a CHECKSUM_PARTIAL start smaller than an estimated minimum network-header length. Its input offsets are relative to skb->data. Using skb_network_offset() here is unsafe. TUN/TAP, virtio-net, and UML parse a received virtio header before skb->network_header is established. On an skb with headroom, the resulting negative offset enlarges the apparent distance to the transport header and can admit a checksum start inside the network header. Pass the data-relative L3 offset to the converter explicitly. IFF_TUN uses zero, AF_PACKET supplies its established network offset, and Ethernet receive paths parse Ethernet and nested VLAN headers with skb_header_pointer(), without changing skb state. Use the same origin for tunnel-offset validation, and make UML propagate conversion failures. This does not require a virtual-machine guest. A TUN or TAP device with virtio-net header support is sufficient to reach these paths. Fixes: 49d14b54a527 ("net: test for not too small csum_start in virtio_net_hdr_to_skb()") Fixes: a2fb4bc4e2a6 ("net: implement virtio helpers to handle UDP GSO tunneling.") Reported-by: Paulos Yibelo Link: https://lore.kernel.org/netdev/20260920004733.6473-2-habte.yibelo@gmail.com/ Cc: stable@vger.kernel.org Signed-off-by: Paulos Yibelo --- Changes in v5: - Replace the not-yet-established skb network-header offset with an explicit data-relative L3 origin. - Cover all in-tree callers, including Ethernet/VLAN receive paths, tunnel metadata, and UML error propagation. - Drop the prior Acked-by and Reviewed-by tags because the code changed. Changes in v4: - State that a TUN device is sufficient and no guest is required, as noted by Michael S. Tsirkin. Changes in v3: - Keep the network-relative comparison on one line for readability, as requested by David Ahern. Changes in v2: - Make nh_min_len an int and remove the casts, as suggested by Michael S. Tsirkin. arch/um/drivers/vector_transports.c | 10 +++- drivers/net/tun_vnet.h | 28 ++++++++++- drivers/net/virtio_net.c | 8 ++- include/linux/virtio_net.h | 76 +++++++++++++++++++++++------ net/packet/af_packet.c | 6 ++- 5 files changed, 106 insertions(+), 22 deletions(-) diff --git a/arch/um/drivers/vector_transports.c b/arch/um/drivers/vector_transports.c index ddd127ee9..79bc05fc6 100644 --- a/arch/um/drivers/vector_transports.c +++ b/arch/um/drivers/vector_transports.c @@ -197,6 +197,7 @@ static int raw_verify_header( uint8_t *header, struct sk_buff *skb, struct vector_private *vp) { struct virtio_net_hdr *vheader = (struct virtio_net_hdr *) header; + int network_offset; if ((vheader->gso_type != VIRTIO_NET_HDR_GSO_NONE) && (vp->req_size != 65536)) { @@ -209,8 +210,13 @@ static int raw_verify_header( if ((vheader->flags & VIRTIO_NET_HDR_F_DATA_VALID) > 0) return 1; - virtio_net_hdr_to_skb(skb, vheader, virtio_legacy_is_little_endian()); - return 0; + network_offset = virtio_net_hdr_get_l3_offset(skb, vheader); + if (network_offset < 0) + return network_offset; + + return virtio_net_hdr_to_skb(skb, vheader, + virtio_legacy_is_little_endian(), + network_offset); } static bool get_uint_param( diff --git a/drivers/net/tun_vnet.h b/drivers/net/tun_vnet.h index f4c652b1f..1c83c359d 100644 --- a/drivers/net/tun_vnet.h +++ b/drivers/net/tun_vnet.h @@ -177,10 +177,27 @@ static inline int tun_vnet_hdr_put(int sz, struct iov_iter *iter, return __tun_vnet_hdr_put(sz, 0, iter, hdr); } +static inline int +tun_vnet_hdr_get_l3_offset(unsigned int flags, const struct sk_buff *skb, + const struct virtio_net_hdr *hdr) +{ + if ((flags & TUN_TYPE_MASK) != IFF_TAP) + return 0; + + return virtio_net_hdr_get_l3_offset(skb, hdr); +} + static inline int tun_vnet_hdr_to_skb(unsigned int flags, struct sk_buff *skb, const struct virtio_net_hdr *hdr) { - return virtio_net_hdr_to_skb(skb, hdr, tun_vnet_is_little_endian(flags)); + int network_offset = tun_vnet_hdr_get_l3_offset(flags, skb, hdr); + + if (network_offset < 0) + return network_offset; + + return virtio_net_hdr_to_skb(skb, hdr, + tun_vnet_is_little_endian(flags), + network_offset); } /* @@ -199,10 +216,17 @@ tun_vnet_hdr_tnl_to_skb(unsigned int flags, netdev_features_t features, struct sk_buff *skb, const struct virtio_net_hdr_v1_hash_tunnel *hdr) { + const struct virtio_net_hdr *vnet_hdr = (const struct virtio_net_hdr *)hdr; + int network_offset = tun_vnet_hdr_get_l3_offset(flags, skb, vnet_hdr); + + if (network_offset < 0) + return network_offset; + return virtio_net_hdr_tnl_to_skb(skb, hdr, features & NETIF_F_GSO_UDP_TUNNEL, features & NETIF_F_GSO_UDP_TUNNEL_CSUM, - tun_vnet_is_little_endian(flags)); + tun_vnet_is_little_endian(flags), + network_offset); } static inline int tun_vnet_hdr_from_skb(unsigned int flags, diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index e34c52d05..059eeb18e 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -2502,6 +2502,7 @@ static void virtnet_receive_done(struct virtnet_info *vi, struct receive_queue * { struct virtio_net_common_hdr *hdr; struct net_device *dev = vi->dev; + int network_offset; hdr = skb_vnet_common_hdr(skb); if (dev->features & NETIF_F_RXHASH && vi->has_rss_hash_report) @@ -2515,9 +2516,12 @@ static void virtnet_receive_done(struct virtnet_info *vi, struct receive_queue * goto frame_err; } - if (virtio_net_hdr_tnl_to_skb(skb, &hdr->tnl_hdr, vi->rx_tnl, + network_offset = virtio_net_hdr_get_l3_offset(skb, &hdr->hdr); + if (network_offset < 0 || + virtio_net_hdr_tnl_to_skb(skb, &hdr->tnl_hdr, vi->rx_tnl, vi->rx_tnl_csum, - virtio_is_little_endian(vi->vdev))) { + virtio_is_little_endian(vi->vdev), + network_offset)) { net_warn_ratelimited("%s: bad gso: type: %x, size: %u, flags %x tunnel %d tnl csum %d\n", dev->name, hdr->hdr.gso_type, hdr->hdr.gso_size, hdr->hdr.flags, diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h index c381b916c..a4c005796 100644 --- a/include/linux/virtio_net.h +++ b/include/linux/virtio_net.h @@ -48,11 +48,49 @@ static inline int virtio_net_hdr_set_proto(struct sk_buff *skb, return 0; } +/* + * Return the L3 offset of an Ethernet frame starting at skb->data. + * The offset is unused without NEEDS_CSUM, so avoid parsing and return zero. + */ +static inline int +virtio_net_hdr_get_l3_offset(const struct sk_buff *skb, + const struct virtio_net_hdr *hdr) +{ + unsigned int parse_depth = VLAN_MAX_DEPTH; + const struct ethhdr *eth; + struct ethhdr ethbuf; + __be16 protocol; + int depth = ETH_HLEN; + + if (!(hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM)) + return 0; + + eth = skb_header_pointer(skb, 0, sizeof(ethbuf), ðbuf); + if (!eth) + return -EINVAL; + + protocol = eth->h_proto; + while (eth_type_vlan(protocol)) { + const struct vlan_hdr *vh; + struct vlan_hdr vhdr; + + vh = skb_header_pointer(skb, depth, sizeof(vhdr), &vhdr); + if (!vh || !--parse_depth) + return -EINVAL; + + protocol = vh->h_vlan_encapsulated_proto; + depth += VLAN_HLEN; + } + + return depth; +} + static inline int __virtio_net_hdr_to_skb(struct sk_buff *skb, const struct virtio_net_hdr *hdr, - bool little_endian, u8 hdr_gso_type) + bool little_endian, u8 hdr_gso_type, + int network_offset) { - unsigned int nh_min_len = sizeof(struct iphdr); + int nh_min_len = sizeof(struct iphdr); unsigned int gso_type = 0; unsigned int thlen = 0; unsigned int p_off = 0; @@ -98,16 +136,20 @@ static inline int __virtio_net_hdr_to_skb(struct sk_buff *skb, u32 start = __virtio16_to_cpu(little_endian, hdr->csum_start); u32 off = __virtio16_to_cpu(little_endian, hdr->csum_offset); u32 needed = start + max_t(u32, thlen, off + sizeof(__sum16)); + int transport_offset; if (!pskb_may_pull(skb, needed)) return -EINVAL; if (!skb_partial_csum_set(skb, start, off)) return -EINVAL; - if (skb_transport_offset(skb) < nh_min_len) + + transport_offset = skb_transport_offset(skb); + if (transport_offset < nh_min_len || network_offset < 0 || + network_offset > transport_offset - nh_min_len) return -EINVAL; - nh_min_len = skb_transport_offset(skb); + nh_min_len = transport_offset; p_off = nh_min_len + thlen; if (!pskb_may_pull(skb, p_off)) return -EINVAL; @@ -206,9 +248,11 @@ static inline int __virtio_net_hdr_to_skb(struct sk_buff *skb, static inline int virtio_net_hdr_to_skb(struct sk_buff *skb, const struct virtio_net_hdr *hdr, - bool little_endian) + bool little_endian, + int network_offset) { - return __virtio_net_hdr_to_skb(skb, hdr, little_endian, hdr->gso_type); + return __virtio_net_hdr_to_skb(skb, hdr, little_endian, hdr->gso_type, + network_offset); } /* This function must be called after virtio_net_hdr_from_skb(). */ @@ -287,7 +331,7 @@ static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb, return 0; } -static inline unsigned int virtio_l3min(bool is_ipv6) +static inline int virtio_l3min(bool is_ipv6) { return is_ipv6 ? sizeof(struct ipv6hdr) : sizeof(struct iphdr); } @@ -297,18 +341,19 @@ virtio_net_hdr_tnl_to_skb(struct sk_buff *skb, const struct virtio_net_hdr_v1_hash_tunnel *vhdr, bool tnl_hdr_negotiated, bool tnl_csum_negotiated, - bool little_endian) + bool little_endian, int network_offset) { const struct virtio_net_hdr *hdr = (const struct virtio_net_hdr *)vhdr; - unsigned int inner_nh, outer_th, inner_th; - unsigned int inner_l3min, outer_l3min; u8 gso_inner_type, gso_tunnel_type; bool outer_isv6, inner_isv6; + int inner_nh, outer_th, inner_th; + int inner_l3min, outer_l3min; int ret; gso_tunnel_type = hdr->gso_type & VIRTIO_NET_HDR_GSO_UDP_TUNNEL; if (!gso_tunnel_type) - return virtio_net_hdr_to_skb(skb, hdr, little_endian); + return virtio_net_hdr_to_skb(skb, hdr, little_endian, + network_offset); /* Tunnel not supported/negotiated, but the hdr asks for it. */ if (!tnl_hdr_negotiated) @@ -332,19 +377,22 @@ virtio_net_hdr_tnl_to_skb(struct sk_buff *skb, outer_isv6 = gso_tunnel_type & VIRTIO_NET_HDR_GSO_UDP_TUNNEL_IPV6; inner_isv6 = gso_inner_type == VIRTIO_NET_HDR_GSO_TCPV6; inner_l3min = virtio_l3min(inner_isv6); - outer_l3min = ETH_HLEN + virtio_l3min(outer_isv6); + outer_l3min = virtio_l3min(outer_isv6); inner_th = __virtio16_to_cpu(little_endian, hdr->csum_start); inner_nh = le16_to_cpu(vhdr->inner_nh_offset); outer_th = le16_to_cpu(vhdr->outer_th_offset); - if (outer_th < outer_l3min || + if (network_offset < 0 || + outer_th < outer_l3min || + network_offset > outer_th - outer_l3min || inner_nh < outer_th + sizeof(struct udphdr) || inner_th < inner_nh + inner_l3min) return -EINVAL; /* Let the basic parsing deal with plain GSO features. */ ret = __virtio_net_hdr_to_skb(skb, hdr, true, - hdr->gso_type & ~gso_tunnel_type); + hdr->gso_type & ~gso_tunnel_type, + network_offset); if (ret) return ret; diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 50cae32ae..04c80e23d 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2901,7 +2901,8 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg) } if (has_vnet_hdr) { - if (virtio_net_hdr_to_skb(skb, &vnet_hdr, vio_le())) { + if (virtio_net_hdr_to_skb(skb, &vnet_hdr, vio_le(), + skb_network_offset(skb))) { tp_len = -EINVAL; goto tpacket_error; } @@ -3103,7 +3104,8 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len) packet_parse_headers(skb, sock); if (vnet_hdr_sz) { - err = virtio_net_hdr_to_skb(skb, &vnet_hdr, vio_le()); + err = virtio_net_hdr_to_skb(skb, &vnet_hdr, vio_le(), + skb_network_offset(skb)); if (err) goto out_free; len += vnet_hdr_sz; -- 2.46.0