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[73.243.191.173]) by smtp.gmail.com with ESMTPSA id v18sm215486ilm.85.2020.02.10.08.59.33 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Feb 2020 08:59:34 -0800 (PST) From: Kelsey Skunberg To: kernel-team@lists.ubuntu.com Subject: [SRU][F/E/B/X][PATCH 1/2] vti[6]: fix packet tx through bpf_redirect() Date: Mon, 10 Feb 2020 09:59:16 -0700 Message-Id: <20200210165917.23193-2-kelsey.skunberg@canonical.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200210165917.23193-1-kelsey.skunberg@canonical.com> References: <20200210165917.23193-1-kelsey.skunberg@canonical.com> MIME-Version: 1.0 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: Nicolas Dichtel BugLink: https://bugs.launchpad.net/bugs/1860969 With an ebpf program that redirects packets through a vti[6] interface, the packets are dropped because no dst is attached. This could also be reproduced with an AF_PACKET socket, with the following python script (vti1 is an ip_vti interface): import socket send_s = socket.socket(socket.AF_PACKET, socket.SOCK_RAW, 0) # scapy # p = IP(src='10.100.0.2', dst='10.200.0.1')/ICMP(type='echo-request') # raw(p) req = b'E\x00\x00\x1c\x00\x01\x00\x00@\x01e\xb2\nd\x00\x02\n\xc8\x00\x01\x08\x00\xf7\xff\x00\x00\x00\x00' send_s.sendto(req, ('vti1', 0x800, 0, 0)) Signed-off-by: Nicolas Dichtel Signed-off-by: Steffen Klassert (cherry picked from commit 95224166a9032ff5d08fca633d37113078ce7d01) Signed-off-by: Kelsey Skunberg --- net/ipv4/ip_vti.c | 13 +++++++++++-- net/ipv6/ip6_vti.c | 13 +++++++++++-- 2 files changed, 22 insertions(+), 4 deletions(-) diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c index cfb025606793..8064e5750b65 100644 --- a/net/ipv4/ip_vti.c +++ b/net/ipv4/ip_vti.c @@ -187,8 +187,17 @@ static netdev_tx_t vti_xmit(struct sk_buff *skb, struct net_device *dev, int mtu; if (!dst) { - dev->stats.tx_carrier_errors++; - goto tx_error_icmp; + struct rtable *rt; + + fl->u.ip4.flowi4_oif = dev->ifindex; + fl->u.ip4.flowi4_flags |= FLOWI_FLAG_ANYSRC; + rt = __ip_route_output_key(dev_net(dev), &fl->u.ip4); + if (IS_ERR(rt)) { + dev->stats.tx_carrier_errors++; + goto tx_error_icmp; + } + dst = &rt->dst; + skb_dst_set(skb, dst); } dst_hold(dst); diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c index 4aa31ccd8a33..f11916120ef3 100644 --- a/net/ipv6/ip6_vti.c +++ b/net/ipv6/ip6_vti.c @@ -449,8 +449,17 @@ vti6_xmit(struct sk_buff *skb, struct net_device *dev, struct flowi *fl) int err = -1; int mtu; - if (!dst) - goto tx_err_link_failure; + if (!dst) { + fl->u.ip6.flowi6_oif = dev->ifindex; + fl->u.ip6.flowi6_flags |= FLOWI_FLAG_ANYSRC; + dst = ip6_route_output(dev_net(dev), NULL, &fl->u.ip6); + if (dst->error) { + dst_release(dst); + dst = NULL; + goto tx_err_link_failure; + } + skb_dst_set(skb, dst); + } dst_hold(dst); dst = xfrm_lookup(t->net, dst, fl, NULL, 0);