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selftests: xfrm: add block rules with adjacent/overlapping subnets 

The existing script lacks a policy pattern that triggers 'tree node
merges' in the kernel.

Consider adding policy affecting following subnet:
pol1: dst 10.0.0.0/22
pol2: dst 10.0.0.0/23 # adds to existing 10.0.0.0/22 node

-> no problems here.  But now, lets consider reverse order:
pol1: dst 10.0.0.0/24
pol2: dst 10.0.0.0/23 # CANNOT add to existing node

When second policy gets added, the kernel must check that the new node
("10.0.0.0/23") doesn't overlap with any existing subnet.

Example:
dst 10.0.0.0/24
dst 10.0.0.1/24
dst 10.0.0.0/23

When the third policy gets added, the kernel must replace the nodes for
the 10.0.0.0/24 and 10.0.0.1/24 policies with a single one and must merge
all the subtrees/lists stored in those nodes into the new node.

The existing test cases only have overlaps with a single node, so no
merging takes place (we can always remove the 'old' node and replace
it with the new subnet prefix).

Add a few 'block policies' in a pattern that triggers this, with a priority
that will make kernel prefer the 'esp' rules.

Make sure the 'tunnel ping' tests still pass after they have been added.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
This commit is contained in:
Florian Westphal 2019-01-04 14:16:59 +01:00 committed by Steffen Klassert
parent d972f3dce8
commit 0977b2383d
1 changed files with 91 additions and 18 deletions
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109
tools/testing/selftests/net/xfrm_policy.sh
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@ -46,6 +46,58 @@ do_esp() {
ip -net $ns xfrm policy add src $rnet dst $lnet dir fwd tmpl src $remote dst $me proto esp mode tunnel priority 100 action allow
}
# add policies with different netmasks, to make sure kernel carries
# the policies contained within new netmask over when search tree is
# re-built.
# peer netns that are supposed to be encapsulated via esp have addresses
# in the 10.0.1.0/24 and 10.0.2.0/24 subnets, respectively.
#
# Adding a policy for '10.0.1.0/23' will make it necessary to
# alter the prefix of 10.0.1.0 subnet.
# In case new prefix overlaps with existing node, the node and all
# policies it carries need to be merged with the existing one(s).
#
# Do that here.
do_overlap()
{
local ns=$1
# adds new nodes to tree (neither network exists yet in policy database).
ip -net $ns xfrm policy add src 10.1.0.0/24 dst 10.0.0.0/24 dir fwd priority 200 action block
# adds a new node in the 10.0.0.0/24 tree (dst node exists).
ip -net $ns xfrm policy add src 10.2.0.0/24 dst 10.0.0.0/24 dir fwd priority 200 action block
# adds a 10.2.0.0/24 node, but for different dst.
ip -net $ns xfrm policy add src 10.2.0.0/24 dst 10.0.1.0/24 dir fwd priority 200 action block
# dst now overlaps with the 10.0.1.0/24 ESP policy in fwd.
# kernel must 'promote' existing one (10.0.0.0/24) to 10.0.0.0/23.
# But 10.0.0.0/23 also includes existing 10.0.1.0/24, so that node
# also has to be merged too, including source-sorted subtrees.
# old:
# 10.0.0.0/24 (node 1 in dst tree of the bin)
# 10.1.0.0/24 (node in src tree of dst node 1)
# 10.2.0.0/24 (node in src tree of dst node 1)
# 10.0.1.0/24 (node 2 in dst tree of the bin)
# 10.0.2.0/24 (node in src tree of dst node 2)
# 10.2.0.0/24 (node in src tree of dst node 2)
#
# The next 'policy add' adds dst '10.0.0.0/23', which means
# that dst node 1 and dst node 2 have to be merged including
# the sub-tree. As no duplicates are allowed, policies in
# the two '10.0.2.0/24' are also merged.
#
# after the 'add', internal search tree should look like this:
# 10.0.0.0/23 (node in dst tree of bin)
# 10.0.2.0/24 (node in src tree of dst node)
# 10.1.0.0/24 (node in src tree of dst node)
# 10.2.0.0/24 (node in src tree of dst node)
#
# 10.0.0.0/24 and 10.0.1.0/24 nodes have been merged as 10.0.0.0/23.
ip -net $ns xfrm policy add src 10.1.0.0/24 dst 10.0.0.0/23 dir fwd priority 200 action block
}
do_esp_policy_get_check() {
local ns=$1
local lnet=$2
@ -160,6 +212,41 @@ check_xfrm() {
return $lret
}
check_exceptions()
{
logpostfix="$1"
local lret=0
# ping to .254 should be excluded from the tunnel (exception is in place).
check_xfrm 0 254
if [ $? -ne 0 ]; then
echo "FAIL: expected ping to .254 to fail ($logpostfix)"
lret=1
else
echo "PASS: ping to .254 bypassed ipsec tunnel ($logpostfix)"
fi
# ping to .253 should use use ipsec due to direct policy exception.
check_xfrm 1 253
if [ $? -ne 0 ]; then
echo "FAIL: expected ping to .253 to use ipsec tunnel ($logpostfix)"
lret=1
else
echo "PASS: direct policy matches ($logpostfix)"
fi
# ping to .2 should use ipsec.
check_xfrm 1 2
if [ $? -ne 0 ]; then
echo "FAIL: expected ping to .2 to use ipsec tunnel ($logpostfix)"
lret=1
else
echo "PASS: policy matches ($logpostfix)"
fi
return $lret
}
#check for needed privileges
if [ "$(id -u)" -ne 0 ];then
echo "SKIP: Need root privileges"
@ -270,31 +357,17 @@ do_exception ns4 10.0.3.10 10.0.3.1 10.0.1.253 10.0.1.240/28
do_exception ns3 dead:3::1 dead:3::10 dead:2::fd dead:2:f0::/96
do_exception ns4 dead:3::10 dead:3::1 dead:1::fd dead:1:f0::/96
# ping to .254 should now be excluded from the tunnel
check_xfrm 0 254
check_exceptions "exceptions"
if [ $? -ne 0 ]; then
echo "FAIL: expected ping to .254 to fail"
ret=1
else
echo "PASS: ping to .254 bypassed ipsec tunnel"
fi
# ping to .253 should use use ipsec due to direct policy exception.
check_xfrm 1 253
if [ $? -ne 0 ]; then
echo "FAIL: expected ping to .253 to use ipsec tunnel"
ret=1
else
echo "PASS: direct policy matches"
fi
# insert block policies with adjacent/overlapping netmasks
do_overlap ns3
# ping to .2 should use ipsec.
check_xfrm 1 2
check_exceptions "exceptions and block policies"
if [ $? -ne 0 ]; then
echo "FAIL: expected ping to .2 to use ipsec tunnel"
ret=1
else
echo "PASS: policy matches"
fi
for i in 1 2 3 4;do ip netns del ns$i;done