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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
	"Hideaki YOSHIFUJI" <yoshfuji@linux-ipv6.org>,
	"David Ahern" <dsahern@kernel.org>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Toke Høiland-Jørgensen" <toke@redhat.com>,
	"Gilad Naaman" <gnaaman@drivenets.com>,
	"Sasha Levin" <sashal@kernel.org>
Subject: [PATCH 5.4 27/40] net: Set true network header for ECN decapsulation
Date: Mon,  2 Aug 2021 15:45:07 +0200	[thread overview]
Message-ID: <20210802134336.259765265@linuxfoundation.org> (raw)
In-Reply-To: <20210802134335.408294521@linuxfoundation.org>

From: Gilad Naaman <gnaaman@drivenets.com>

[ Upstream commit 227adfb2b1dfbc53dfc53b9dd7a93a6298ff7c56 ]

In cases where the header straight after the tunnel header was
another ethernet header (TEB), instead of the network header,
the ECN decapsulation code would treat the ethernet header as if
it was an IP header, resulting in mishandling and possible
wrong drops or corruption of the IP header.

In this case, ECT(1) is sent, so IP_ECN_decapsulate tries to copy it to the
inner IPv4 header, and correct its checksum.

The offset of the ECT bits in an IPv4 header corresponds to the
lower 2 bits of the second octet of the destination MAC address
in the ethernet header.
The IPv4 checksum corresponds to end of the source address.

In order to reproduce:

    $ ip netns add A
    $ ip netns add B
    $ ip -n A link add _v0 type veth peer name _v1 netns B
    $ ip -n A link set _v0 up
    $ ip -n A addr add dev _v0 10.254.3.1/24
    $ ip -n A route add default dev _v0 scope global
    $ ip -n B link set _v1 up
    $ ip -n B addr add dev _v1 10.254.1.6/24
    $ ip -n B route add default dev _v1 scope global
    $ ip -n B link add gre1 type gretap local 10.254.1.6 remote 10.254.3.1 key 0x49000000
    $ ip -n B link set gre1 up

    # Now send an IPv4/GRE/Eth/IPv4 frame where the outer header has ECT(1),
    # and the inner header has no ECT bits set:

    $ cat send_pkt.py
        #!/usr/bin/env python3
        from scapy.all import *

        pkt = IP(b'E\x01\x00\xa7\x00\x00\x00\x00@/`%\n\xfe\x03\x01\n\xfe\x01\x06 \x00eXI\x00'
                 b'\x00\x00\x18\xbe\x92\xa0\xee&\x18\xb0\x92\xa0l&\x08\x00E\x00\x00}\x8b\x85'
                 b'@\x00\x01\x01\xe4\xf2\x82\x82\x82\x01\x82\x82\x82\x02\x08\x00d\x11\xa6\xeb'
                 b'3\x1e\x1e\\xf3\\xf7`\x00\x00\x00\x00ZN\x00\x00\x00\x00\x00\x00\x10\x11\x12'
                 b'\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f !"#$%&\'()*+,-./01234'
                 b'56789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ')

        send(pkt)
    $ sudo ip netns exec B tcpdump -neqlllvi gre1 icmp & ; sleep 1
    $ sudo ip netns exec A python3 send_pkt.py

In the original packet, the source/destinatio MAC addresses are
dst=18:be:92:a0:ee:26 src=18:b0:92:a0:6c:26

In the received packet, they are
dst=18:bd:92:a0:ee:26 src=18:b0:92:a0:6c:27

Thanks to Lahav Schlesinger <lschlesinger@drivenets.com> and Isaac Garzon <isaac@speed.io>
for helping me pinpoint the origin.

Fixes: b723748750ec ("tunnel: Propagate ECT(1) when decapsulating as recommended by RFC6040")
Cc: David S. Miller <davem@davemloft.net>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: David Ahern <dsahern@kernel.org>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Gilad Naaman <gnaaman@drivenets.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/ipv4/ip_tunnel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index eb381a24a8f8..38d3095ef979 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -391,7 +391,7 @@ int ip_tunnel_rcv(struct ip_tunnel *tunnel, struct sk_buff *skb,
 		tunnel->i_seqno = ntohl(tpi->seq) + 1;
 	}
 
-	skb_reset_network_header(skb);
+	skb_set_network_header(skb, (tunnel->dev->type == ARPHRD_ETHER) ? ETH_HLEN : 0);
 
 	err = IP_ECN_decapsulate(iph, skb);
 	if (unlikely(err)) {
-- 
2.30.2




  parent reply	other threads:[~2021-08-02 13:58 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-02 13:44 [PATCH 5.4 00/40] 5.4.138-rc1 review Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 01/40] net_sched: check error pointer in tcf_dump_walker() Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 02/40] x86/asm: Ensure asm/proto.h can be included stand-alone Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 03/40] btrfs: fix rw device counting in __btrfs_free_extra_devids Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 04/40] btrfs: mark compressed range uptodate only if all bio succeed Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 05/40] Revert "ACPI: resources: Add checks for ACPI IRQ override" Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 06/40] x86/kvm: fix vcpu-id indexed array sizes Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 07/40] KVM: add missing compat KVM_CLEAR_DIRTY_LOG Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 08/40] ocfs2: fix zero out valid data Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 09/40] ocfs2: issue zeroout to EOF blocks Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 10/40] can: j1939: j1939_xtp_rx_dat_one(): fix rxtimer value between consecutive TP.DT to 750ms Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 11/40] can: raw: raw_setsockopt(): fix raw_rcv panic for sock UAF Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 12/40] can: mcba_usb_start(): add missing urb->transfer_dma initialization Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 13/40] can: usb_8dev: fix memory leak Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 14/40] can: ems_usb: " Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 15/40] can: esd_usb2: " Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 16/40] HID: wacom: Re-enable touch by default for Cintiq 24HDT / 27QHDT Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 17/40] NIU: fix incorrect error return, missed in previous revert Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 18/40] nfc: nfcsim: fix use after free during module unload Greg Kroah-Hartman
2021-08-02 13:44 ` [PATCH 5.4 19/40] cfg80211: Fix possible memory leak in function cfg80211_bss_update Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 20/40] netfilter: conntrack: adjust stop timestamp to real expiry value Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 21/40] netfilter: nft_nat: allow to specify layer 4 protocol NAT only Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 22/40] i40e: Fix logic of disabling queues Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 23/40] i40e: Fix firmware LLDP agent related warning Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 24/40] i40e: Fix queue-to-TC mapping on Tx Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 25/40] i40e: Fix log TC creation failure when max num of queues is exceeded Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 26/40] tipc: fix sleeping in tipc accept routine Greg Kroah-Hartman
2021-08-02 13:45 ` Greg Kroah-Hartman [this message]
2021-08-02 13:45 ` [PATCH 5.4 28/40] mlx4: Fix missing error code in mlx4_load_one() Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 29/40] net: llc: fix skb_over_panic Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 30/40] net/mlx5: Fix flow table chaining Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 31/40] net/mlx5e: Fix nullptr in mlx5e_hairpin_get_mdev() Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 32/40] sctp: fix return value check in __sctp_rcv_asconf_lookup Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 33/40] tulip: windbond-840: Fix missing pci_disable_device() in probe and remove Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 34/40] sis900: " Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 35/40] can: hi311x: fix a signedness bug in hi3110_cmd() Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 36/40] PCI: mvebu: Setup BAR0 in order to fix MSI Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 37/40] powerpc/pseries: Fix regression while building external modules Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 38/40] Revert "perf map: Fix dso->nsinfo refcounting" Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 39/40] i40e: Add additional info to PHY type error Greg Kroah-Hartman
2021-08-02 13:45 ` [PATCH 5.4 40/40] can: j1939: j1939_session_deactivate(): clarify lifetime of session object Greg Kroah-Hartman
2021-08-03  9:12 ` [PATCH 5.4 00/40] 5.4.138-rc1 review Naresh Kamboju
2021-08-03 10:35 ` Sudip Mukherjee
2021-08-03 19:16 ` Guenter Roeck

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