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Code Issues Releases Wiki Activity

flow_dissector: fix TTL and TOS dissection on IPv4 fragments

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the following command:

 # tc filter add dev $h2 ingress protocol ip pref 1 handle 101 flower \
   $tcflags dst_ip 192.0.2.2 ip_ttl 63 action drop

doesn't drop all IPv4 packets that match the configured TTL / destination
address. In particular, if "fragment offset" or "more fragments" have non
zero value in the IPv4 header, setting of FLOW_DISSECTOR_KEY_IP is simply
ignored. Fix this dissecting IPv4 TTL and TOS before fragment info; while
at it, add a selftest for tc flower's match on 'ip_ttl' that verifies the
correct behavior.

Fixes: 518d8a2e9b ("net/flow_dissector: add support for dissection of misc ip header fields")
Reported-by: Shuang Li <shuali@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Davide Caratti 2021-02-12 16:12:25 +01:00 committed by David S. Miller
parent 39935dccb2
commit d212683805
2 changed files with 40 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
net/core/flow_dissector.c
View file

@ -1050,6 +1050,9 @@ bool __skb_flow_dissect(const struct net *net,
key_control->addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
}
__skb_flow_dissect_ipv4(skb, flow_dissector,
target_container, data, iph);
if (ip_is_fragment(iph)) {
key_control->flags |= FLOW_DIS_IS_FRAGMENT;
@ -1066,9 +1069,6 @@ bool __skb_flow_dissect(const struct net *net,
}
}
__skb_flow_dissect_ipv4(skb, flow_dissector,
target_container, data, iph);
break;
}
case htons(ETH_P_IPV6): {

38
tools/testing/selftests/net/forwarding/tc_flower.sh
View file

@ -3,7 +3,7 @@
ALL_TESTS="match_dst_mac_test match_src_mac_test match_dst_ip_test \
match_src_ip_test match_ip_flags_test match_pcp_test match_vlan_test \
match_ip_tos_test match_indev_test"
match_ip_tos_test match_indev_test match_ip_ttl_test"
NUM_NETIFS=2
source tc_common.sh
source lib.sh
@ -310,6 +310,42 @@ match_ip_tos_test()
log_test "ip_tos match ($tcflags)"
}
match_ip_ttl_test()
{
RET=0
tc filter add dev $h2 ingress protocol ip pref 1 handle 101 flower \
$tcflags dst_ip 192.0.2.2 ip_ttl 63 action drop
tc filter add dev $h2 ingress protocol ip pref 2 handle 102 flower \
$tcflags dst_ip 192.0.2.2 action drop
$MZ $h1 -c 1 -p 64 -a $h1mac -b $h2mac -A 192.0.2.1 -B 192.0.2.2 \
-t ip "ttl=63" -q
$MZ $h1 -c 1 -p 64 -a $h1mac -b $h2mac -A 192.0.2.1 -B 192.0.2.2 \
-t ip "ttl=63,mf,frag=256" -q
tc_check_packets "dev $h2 ingress" 102 1
check_fail $? "Matched on the wrong filter (no check on ttl)"
tc_check_packets "dev $h2 ingress" 101 2
check_err $? "Did not match on correct filter (ttl=63)"
$MZ $h1 -c 1 -p 64 -a $h1mac -b $h2mac -A 192.0.2.1 -B 192.0.2.2 \
-t ip "ttl=255" -q
tc_check_packets "dev $h2 ingress" 101 3
check_fail $? "Matched on a wrong filter (ttl=63)"
tc_check_packets "dev $h2 ingress" 102 1
check_err $? "Did not match on correct filter (no check on ttl)"
tc filter del dev $h2 ingress protocol ip pref 2 handle 102 flower
tc filter del dev $h2 ingress protocol ip pref 1 handle 101 flower
log_test "ip_ttl match ($tcflags)"
}
match_indev_test()
{
RET=0