From 55f0c2bb9bd52d73bb458bd6422b09f413ad20dc Mon Sep 17 00:00:00 2001 From: Ido Schimmel Date: Mon, 15 Jul 2024 17:23:54 +0300 Subject: [PATCH] ipv4: Fix incorrect TOS in fibmatch route get reply BugLink: https://bugs.launchpad.net/bugs/2083196 [ Upstream commit f036e68212c11e5a7edbb59b5e25299341829485 ] The TOS value that is returned to user space in the route get reply is the one with which the lookup was performed ('fl4->flowi4_tos'). This is fine when the matched route is configured with a TOS as it would not match if its TOS value did not match the one with which the lookup was performed. However, matching on TOS is only performed when the route's TOS is not zero. It is therefore possible to have the kernel incorrectly return a non-zero TOS: # ip link add name dummy1 up type dummy # ip address add 192.0.2.1/24 dev dummy1 # ip route get fibmatch 192.0.2.2 tos 0xfc 192.0.2.0/24 tos 0x1c dev dummy1 proto kernel scope link src 192.0.2.1 Fix by instead returning the DSCP field from the FIB result structure which was populated during the route lookup. Output after the patch: # ip link add name dummy1 up type dummy # ip address add 192.0.2.1/24 dev dummy1 # ip route get fibmatch 192.0.2.2 tos 0xfc 192.0.2.0/24 dev dummy1 proto kernel scope link src 192.0.2.1 Extend the existing selftests to not only verify that the correct route is returned, but that it is also returned with correct "tos" value (or without it). Fixes: b61798130f1b ("net: ipv4: RTM_GETROUTE: return matched fib result when requested") Signed-off-by: Ido Schimmel Reviewed-by: David Ahern Reviewed-by: Guillaume Nault Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin Signed-off-by: Portia Stephens Signed-off-by: Roxana Nicolescu --- net/ipv4/route.c | 2 +- tools/testing/selftests/net/fib_tests.sh | 24 ++++++++++++------------ 2 files changed, 13 insertions(+), 13 deletions(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index e58adfd671fe..fa6179c52d02 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -3344,7 +3344,7 @@ static int inet_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh, fri.tb_id = table_id; fri.dst = res.prefix; fri.dst_len = res.prefixlen; - fri.dscp = inet_dsfield_to_dscp(fl4.flowi4_tos); + fri.dscp = res.dscp; fri.type = rt->rt_type; fri.offload = 0; fri.trap = 0; diff --git a/tools/testing/selftests/net/fib_tests.sh b/tools/testing/selftests/net/fib_tests.sh index b3ecccbbfcd2..3199c921f5f4 100755 --- a/tools/testing/selftests/net/fib_tests.sh +++ b/tools/testing/selftests/net/fib_tests.sh @@ -1633,53 +1633,53 @@ ipv4_rt_dsfield() # DSCP 0x10 should match the specific route, no matter the ECN bits $IP route get fibmatch 172.16.102.1 dsfield 0x10 | \ - grep -q "via 172.16.103.2" + grep -q "172.16.102.0/24 tos 0x10 via 172.16.103.2" log_test $? 0 "IPv4 route with DSCP and ECN:Not-ECT" $IP route get fibmatch 172.16.102.1 dsfield 0x11 | \ - grep -q "via 172.16.103.2" + grep -q "172.16.102.0/24 tos 0x10 via 172.16.103.2" log_test $? 0 "IPv4 route with DSCP and ECN:ECT(1)" $IP route get fibmatch 172.16.102.1 dsfield 0x12 | \ - grep -q "via 172.16.103.2" + grep -q "172.16.102.0/24 tos 0x10 via 172.16.103.2" log_test $? 0 "IPv4 route with DSCP and ECN:ECT(0)" $IP route get fibmatch 172.16.102.1 dsfield 0x13 | \ - grep -q "via 172.16.103.2" + grep -q "172.16.102.0/24 tos 0x10 via 172.16.103.2" log_test $? 0 "IPv4 route with DSCP and ECN:CE" # Unknown DSCP should match the generic route, no matter the ECN bits $IP route get fibmatch 172.16.102.1 dsfield 0x14 | \ - grep -q "via 172.16.101.2" + grep -q "172.16.102.0/24 via 172.16.101.2" log_test $? 0 "IPv4 route with unknown DSCP and ECN:Not-ECT" $IP route get fibmatch 172.16.102.1 dsfield 0x15 | \ - grep -q "via 172.16.101.2" + grep -q "172.16.102.0/24 via 172.16.101.2" log_test $? 0 "IPv4 route with unknown DSCP and ECN:ECT(1)" $IP route get fibmatch 172.16.102.1 dsfield 0x16 | \ - grep -q "via 172.16.101.2" + grep -q "172.16.102.0/24 via 172.16.101.2" log_test $? 0 "IPv4 route with unknown DSCP and ECN:ECT(0)" $IP route get fibmatch 172.16.102.1 dsfield 0x17 | \ - grep -q "via 172.16.101.2" + grep -q "172.16.102.0/24 via 172.16.101.2" log_test $? 0 "IPv4 route with unknown DSCP and ECN:CE" # Null DSCP should match the generic route, no matter the ECN bits $IP route get fibmatch 172.16.102.1 dsfield 0x00 | \ - grep -q "via 172.16.101.2" + grep -q "172.16.102.0/24 via 172.16.101.2" log_test $? 0 "IPv4 route with no DSCP and ECN:Not-ECT" $IP route get fibmatch 172.16.102.1 dsfield 0x01 | \ - grep -q "via 172.16.101.2" + grep -q "172.16.102.0/24 via 172.16.101.2" log_test $? 0 "IPv4 route with no DSCP and ECN:ECT(1)" $IP route get fibmatch 172.16.102.1 dsfield 0x02 | \ - grep -q "via 172.16.101.2" + grep -q "172.16.102.0/24 via 172.16.101.2" log_test $? 0 "IPv4 route with no DSCP and ECN:ECT(0)" $IP route get fibmatch 172.16.102.1 dsfield 0x03 | \ - grep -q "via 172.16.101.2" + grep -q "172.16.102.0/24 via 172.16.101.2" log_test $? 0 "IPv4 route with no DSCP and ECN:CE" }