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ofproto-xlate: Fix crash when forwarding packet between legacy_l3 tun…
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…nels.

A packet received from a tunnel port with legacy_l3 packet-type (e.g.
lisp, L3 gre, gtpu) is conceptually wrapped in a dummy Ethernet header
for processing in an OF pipeline that is not packet-type-aware. Before
transmission of the packet to another legacy_l3 tunnel port, the dummy
Ethernet header is stripped again.

In ofproto-xlate, wrapping in the dummy Ethernet header is done by
simply changing the packet_type to PT_ETH. The generation of the
push_eth datapath action is deferred until the packet's flow changes
need to be committed, for example at output to a normal port. The
deferred Ethernet encapsulation is marked in the pending_encap flag.

This patch fixes a bug in the translation of the output action to a
legacy_l3 tunnel port, where the packet_type of the flow is reverted
from PT_ETH to PT_IPV4 or PT_IPV6 (depending on the dl_type) to remove
its Ethernet header without clearing the pending_encap flag if it was
set. At the subsequent commit of the flow changes, the unexpected
combination of pending_encap == true with an PT_IPV4 or PT_IPV6
packet_type hit the OVS_NOT_REACHED() abortion clause.

The pending_encap is now cleared in this situation.

Reported-by: Dincer Beken <[email protected]>
Signed-off-by: Jan Scheurich <[email protected]>
Co-authored-by: Dincer Beken <[email protected]>
Signed-off-by: Dincer Beken <[email protected]>
Signed-off-by: Ilya Maximets <[email protected]>
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@JanScheurich @dbeken85 @igsilya
2 people authored and igsilya committed Apr 26, 2022
1 parent 4ea1bb6 commit 0e0eef5
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Showing 2 changed files with 28 additions and 2 deletions.
4 changes: 4 additions & 0 deletions ofproto/ofproto-dpif-xlate.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4195,6 +4195,10 @@ compose_output_action__(struct xlate_ctx *ctx, ofp_port_t ofp_port,
if (xport->pt_mode == NETDEV_PT_LEGACY_L3) {
flow->packet_type = PACKET_TYPE_BE(OFPHTN_ETHERTYPE,
ntohs(flow->dl_type));
if (ctx->pending_encap) {
/* The Ethernet header was not actually added yet. */
ctx->pending_encap = false;
}
}
}

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26 changes: 24 additions & 2 deletions tests/tunnel-push-pop.at
View file
Original file line number Diff line number Diff line change
Expand Up @@ -546,6 +546,28 @@ AT_CHECK([ovs-ofctl dump-ports int-br | grep 'port [[37]]' | sort], [0], [dnl
port 7: rx pkts=5, bytes=434, drop=?, errs=?, frame=?, over=?, crc=?
])

dnl Send out packets received from L3GRE tunnel back to L3GRE tunnel
AT_CHECK([ovs-ofctl del-flows int-br])
AT_CHECK([ovs-ofctl add-flow int-br "in_port=7,actions=set_field:3->in_port,7"])
AT_CHECK([ovs-vsctl -- set Interface br0 options:pcap=br0.pcap])

AT_CHECK([ovs-appctl netdev-dummy/receive p0 'aa55aa550000001b213cab6408004500007079464000402fba630101025c0101025820000800000001c845000054ba200000400184861e0000011e00000200004227e75400030af3195500000000f265010000000000101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f3031323334353637'])
AT_CHECK([ovs-appctl netdev-dummy/receive p0 'aa55aa550000001b213cab6408004500007079464000402fba630101025c0101025820000800000001c845000054ba200000400184861e0000011e00000200004227e75400030af3195500000000f265010000000000101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f3031323334353637'])
AT_CHECK([ovs-appctl netdev-dummy/receive p0 'aa55aa550000001b213cab6408004500007079464000402fba630101025c0101025820000800000001c845000054ba200000400184861e0000011e00000200004227e75400030af3195500000000f265010000000000101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f3031323334353637'])

ovs-appctl time/warp 1000

AT_CHECK([ovs-pcap p0.pcap > p0.pcap.txt 2>&1])
AT_CHECK([tail -6 p0.pcap.txt], [0], [dnl
aa55aa550000001b213cab6408004500007079464000402fba630101025c0101025820000800000001c845000054ba200000400184861e0000011e00000200004227e75400030af3195500000000f265010000000000101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f3031323334353637
001b213cab64aa55aa55000008004500007000004000402f33aa010102580101025c20000800000001c845000054ba200000400184861e0000011e00000200004227e75400030af3195500000000f265010000000000101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f3031323334353637
aa55aa550000001b213cab6408004500007079464000402fba630101025c0101025820000800000001c845000054ba200000400184861e0000011e00000200004227e75400030af3195500000000f265010000000000101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f3031323334353637
001b213cab64aa55aa55000008004500007000004000402f33aa010102580101025c20000800000001c845000054ba200000400184861e0000011e00000200004227e75400030af3195500000000f265010000000000101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f3031323334353637
aa55aa550000001b213cab6408004500007079464000402fba630101025c0101025820000800000001c845000054ba200000400184861e0000011e00000200004227e75400030af3195500000000f265010000000000101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f3031323334353637
001b213cab64aa55aa55000008004500007000004000402f33aa010102580101025c20000800000001c845000054ba200000400184861e0000011e00000200004227e75400030af3195500000000f265010000000000101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f3031323334353637
])


dnl Check decapsulation of Geneve packet with options
AT_CAPTURE_FILE([ofctl_monitor.log])
AT_CHECK([ovs-ofctl monitor int-br 65534 --detach --no-chdir --pidfile 2> ofctl_monitor.log])
Expand All @@ -565,8 +587,8 @@ icmp,vlan_tci=0x0000,dl_src=be:b6:f4:e1:49:4a,dl_dst=fe:71:d8:83:72:4f,nw_src=30
AT_CHECK([ovs-ofctl dump-ports int-br | grep 'port 5'], [0], [dnl
port 5: rx pkts=1, bytes=98, drop=?, errs=?, frame=?, over=?, crc=?
])
AT_CHECK([ovs-appctl dpif/dump-flows int-br | grep 'in_port(6081)'], [0], [dnl
tunnel(tun_id=0x7b,src=1.1.2.92,dst=1.1.2.88,geneve({class=0xffff,type=0x80,len=4,0xa/0xf}{class=0xffff,type=0,len=4}),flags(-df-csum+key)),recirc_id(0),in_port(6081),packet_type(ns=0,id=0),eth_type(0x0800),ipv4(frag=no), packets:0, bytes:0, used:never, actions:userspace(pid=0,controller(reason=1,dont_send=0,continuation=0,recirc_id=2,rule_cookie=0,controller_id=0,max_len=65535))
AT_CHECK([ovs-appctl dpif/dump-flows int-br | grep 'in_port(6081)' | sed -e 's/recirc_id=[[0-9]]*/recirc_id=<cleared>/g'], [0], [dnl
tunnel(tun_id=0x7b,src=1.1.2.92,dst=1.1.2.88,geneve({class=0xffff,type=0x80,len=4,0xa/0xf}{class=0xffff,type=0,len=4}),flags(-df-csum+key)),recirc_id(0),in_port(6081),packet_type(ns=0,id=0),eth_type(0x0800),ipv4(frag=no), packets:0, bytes:0, used:never, actions:userspace(pid=0,controller(reason=1,dont_send=0,continuation=0,recirc_id=<cleared>,rule_cookie=0,controller_id=0,max_len=65535))
])

dnl Receive VXLAN with different MAC and verify that the neigh cache gets updated
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