selftests: netfilter: check stateless nat udp checksum fixup

BugLink: https://bugs.launchpad.net/bugs/1960516
commit aad51ca71ad83273e8826d6cfdcf53c98748d1fa upstream.

Add a test that sends large udp packet (which is fragmented)
via a stateless nft nat rule, i.e. 'ip saddr set 10.2.3.4'
and check that the datagram is received by peer.

On kernels without
commit 4e1860a38637 ("netfilter: nft_payload: do not update layer 4 checksum when mangling fragments")',
this will fail with:

cmp: EOF on /tmp/tmp.V1q0iXJyQF which is empty
-rw------- 1 root root 4096 Jan 24 22:03 /tmp/tmp.Aaqnq4rBKS
-rw------- 1 root root    0 Jan 24 22:03 /tmp/tmp.V1q0iXJyQF
ERROR: in and output file mismatch when checking udp with stateless nat
FAIL: nftables v1.0.0 (Fearless Fosdick #2)

On patched kernels, this will show:
PASS: IP statless for ns2-PFp89amx

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

diff --git a/tools/testing/selftests/netfilter/nft_nat.sh b/tools/testing/selftests/netfilter/nft_nat.sh
index da1c1e4b6c86bf87ccfd8a01f4dbd99295081367..781fa2d9ea9d52c4a908d7111ba30e9a0e1010b1 100755 (executable)
--- a/tools/testing/selftests/netfilter/nft_nat.sh
+++ b/tools/testing/selftests/netfilter/nft_nat.sh
@@ -885,6 +885,144 @@ EOF
        ip netns exec "$ns0" nft delete table $family nat
 }
 
+test_stateless_nat_ip()
+{
+       local lret=0
+
+       ip netns exec "$ns0" sysctl net.ipv4.conf.veth0.forwarding=1 > /dev/null
+       ip netns exec "$ns0" sysctl net.ipv4.conf.veth1.forwarding=1 > /dev/null
+
+       ip netns exec "$ns2" ping -q -c 1 10.0.1.99 > /dev/null # ping ns2->ns1
+       if [ $? -ne 0 ] ; then
+               echo "ERROR: cannot ping $ns1 from $ns2 before loading stateless rules"
+               return 1
+       fi
+
+ip netns exec "$ns0" nft -f /dev/stdin <<EOF
+table ip stateless {
+       map xlate_in {
+               typeof meta iifname . ip saddr . ip daddr : ip daddr
+               elements = {
+                       "veth1" . 10.0.2.99 . 10.0.1.99 : 10.0.2.2,
+               }
+       }
+       map xlate_out {
+               typeof meta iifname . ip saddr . ip daddr : ip daddr
+               elements = {
+                       "veth0" . 10.0.1.99 . 10.0.2.2 : 10.0.2.99
+               }
+       }
+
+       chain prerouting {
+               type filter hook prerouting priority -400; policy accept;
+               ip saddr set meta iifname . ip saddr . ip daddr map @xlate_in
+               ip daddr set meta iifname . ip saddr . ip daddr map @xlate_out
+       }
+}
+EOF
+       if [ $? -ne 0 ]; then
+               echo "SKIP: Could not add ip statless rules"
+               return $ksft_skip
+       fi
+
+       reset_counters
+
+       ip netns exec "$ns2" ping -q -c 1 10.0.1.99 > /dev/null # ping ns2->ns1
+       if [ $? -ne 0 ] ; then
+               echo "ERROR: cannot ping $ns1 from $ns2 with stateless rules"
+               lret=1
+       fi
+
+       # ns1 should have seen packets from .2.2, due to stateless rewrite.
+       expect="packets 1 bytes 84"
+       cnt=$(ip netns exec "$ns1" nft list counter inet filter ns0insl | grep -q "$expect")
+       if [ $? -ne 0 ]; then
+               bad_counter "$ns1" ns0insl "$expect" "test_stateless 1"
+               lret=1
+       fi
+
+       for dir in "in" "out" ; do
+               cnt=$(ip netns exec "$ns2" nft list counter inet filter ns1${dir} | grep -q "$expect")
+               if [ $? -ne 0 ]; then
+                       bad_counter "$ns2" ns1$dir "$expect" "test_stateless 2"
+                       lret=1
+               fi
+       done
+
+       # ns1 should not have seen packets from ns2, due to masquerade
+       expect="packets 0 bytes 0"
+       for dir in "in" "out" ; do
+               cnt=$(ip netns exec "$ns1" nft list counter inet filter ns2${dir} | grep -q "$expect")
+               if [ $? -ne 0 ]; then
+                       bad_counter "$ns1" ns0$dir "$expect" "test_stateless 3"
+                       lret=1
+               fi
+
+               cnt=$(ip netns exec "$ns0" nft list counter inet filter ns1${dir} | grep -q "$expect")
+               if [ $? -ne 0 ]; then
+                       bad_counter "$ns0" ns1$dir "$expect" "test_stateless 4"
+                       lret=1
+               fi
+       done
+
+       reset_counters
+
+       socat -h > /dev/null 2>&1
+       if [ $? -ne 0 ];then
+               echo "SKIP: Could not run stateless nat frag test without socat tool"
+               if [ $lret -eq 0 ]; then
+                       return $ksft_skip
+               fi
+
+               ip netns exec "$ns0" nft delete table ip stateless
+               return $lret
+       fi
+
+       local tmpfile=$(mktemp)
+       dd if=/dev/urandom of=$tmpfile bs=4096 count=1 2>/dev/null
+
+       local outfile=$(mktemp)
+       ip netns exec "$ns1" timeout 3 socat -u UDP4-RECV:4233 OPEN:$outfile < /dev/null &
+       sc_r=$!
+
+       sleep 1
+       # re-do with large ping -> ip fragmentation
+       ip netns exec "$ns2" timeout 3 socat - UDP4-SENDTO:"10.0.1.99:4233" < "$tmpfile" > /dev/null
+       if [ $? -ne 0 ] ; then
+               echo "ERROR: failed to test udp $ns1 to $ns2 with stateless ip nat" 1>&2
+               lret=1
+       fi
+
+       wait
+
+       cmp "$tmpfile" "$outfile"
+       if [ $? -ne 0 ]; then
+               ls -l "$tmpfile" "$outfile"
+               echo "ERROR: in and output file mismatch when checking udp with stateless nat" 1>&2
+               lret=1
+       fi
+
+       rm -f "$tmpfile" "$outfile"
+
+       # ns1 should have seen packets from 2.2, due to stateless rewrite.
+       expect="packets 3 bytes 4164"
+       cnt=$(ip netns exec "$ns1" nft list counter inet filter ns0insl | grep -q "$expect")
+       if [ $? -ne 0 ]; then
+               bad_counter "$ns1" ns0insl "$expect" "test_stateless 5"
+               lret=1
+       fi
+
+       ip netns exec "$ns0" nft delete table ip stateless
+       if [ $? -ne 0 ]; then
+               echo "ERROR: Could not delete table ip stateless" 1>&2
+               lret=1
+       fi
+
+       test $lret -eq 0 && echo "PASS: IP statless for $ns2"
+
+       return $lret
+}
+
 # ip netns exec "$ns0" ping -c 1 -q 10.0.$i.99
 for i in 0 1 2; do
 ip netns exec ns$i-$sfx nft -f /dev/stdin <<EOF
@@ -951,6 +1089,19 @@ table inet filter {
 EOF
 done
 
+# special case for stateless nat check, counter needs to
+# be done before (input) ip defragmentation
+ip netns exec ns1-$sfx nft -f /dev/stdin <<EOF
+table inet filter {
+       counter ns0insl {}
+
+       chain pre {
+               type filter hook prerouting priority -400; policy accept;
+               ip saddr 10.0.2.2 counter name "ns0insl"
+       }
+}
+EOF
+
 sleep 3
 # test basic connectivity
 for i in 1 2; do
@@ -1005,6 +1156,7 @@ $test_inet_nat && test_redirect inet
 $test_inet_nat && test_redirect6 inet
 
 test_port_shadowing
+test_stateless_nat_ip
 
 if [ $ret -ne 0 ];then
        echo -n "FAIL: "