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| H A D | ip_vti.c | diff 7263a5187f9e9de45fcb51349cf0e031142c19a1 Tue Oct 08 17:21:22 CEST 2013 Christophe Gouault <christophe.gouault@6wind.com> vti: get rid of nf mark rule in prerouting
This patch fixes and improves the use of vti interfaces (while
lightly changing the way of configuring them).
Currently:
- it is necessary to identify and mark inbound IPsec
packets destined to each vti interface, via netfilter rules in
the mangle table at prerouting hook.
- the vti module cannot retrieve the right tunnel in input since
commit b9959fd3: vti tunnels all have an i_key, but the tunnel lookup
is done with flag TUNNEL_NO_KEY, so there no chance to retrieve them.
- the i_key is used by the outbound processing as a mark to lookup
for the right SP and SA bundle.
This patch uses the o_key to store the vti mark (instead of i_key) and
enables:
- to avoid the need for previously marking the inbound skbuffs via a
netfilter rule.
- to properly retrieve the right tunnel in input, only based on the IPsec
packet outer addresses.
- to properly perform an inbound policy check (using the tunnel o_key
as a mark).
- to properly perform an outbound SPD and SAD lookup (using the tunnel
o_key as a mark).
- to keep the current mark of the skbuff. The skbuff mark is neither
used nor changed by the vti interface. Only the vti interface o_key
is used.
SAs have a wildcard mark.
SPs have a mark equal to the vti interface o_key.
The vti interface must be created as follows (i_key = 0, o_key = mark):
ip link add vti1 mode vti local 1.1.1.1 remote 2.2.2.2 okey 1
The SPs attached to vti1 must be created as follows (mark = vti1 o_key):
ip xfrm policy add dir out mark 1 tmpl src 1.1.1.1 dst 2.2.2.2 \
proto esp mode tunnel
ip xfrm policy add dir in mark 1 tmpl src 2.2.2.2 dst 1.1.1.1 \
proto esp mode tunnel
The SAs are created with the default wildcard mark. There is no
distinction between global vs. vti SAs. Just their addresses will
possibly link them to a vti interface:
ip xfrm state add src 1.1.1.1 dst 2.2.2.2 proto esp spi 1000 mode tunnel \
enc "cbc(aes)" "azertyuiopqsdfgh"
ip xfrm state add src 2.2.2.2 dst 1.1.1.1 proto esp spi 2000 mode tunnel \
enc "cbc(aes)" "sqbdhgqsdjqjsdfh"
To avoid matching "global" (not vti) SPs in vti interfaces, global SPs
should no use the default wildcard mark, but explicitly match mark 0.
To avoid a double SPD lookup in input and output (in global and vti SPDs),
the NOPOLICY and NOXFRM options should be set on the vti interfaces:
echo 1 > /proc/sys/net/ipv4/conf/vti1/disable_policy
echo 1 > /proc/sys/net/ipv4/conf/vti1/disable_xfrm
The outgoing traffic is steered to vti1 by a route via the vti interface:
ip route add 192.168.0.0/16 dev vti1
The incoming IPsec traffic is steered to vti1 because its outer addresses
match the vti1 tunnel configuration.
Signed-off-by: Christophe Gouault <christophe.gouault@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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