[PATCH 6.0 143/157] ipv4: Fix incorrect route flushing when table ID 0 is used

Greg Kroah-Hartman
2022-12-12T13:45:42Z

From: Ido Schimmel <idosch@nvidia.com>

[ Upstream commit c0d999348e01df03e0a7f550351f3907fabbf611 ]

Cited commit added the table ID to the FIB info structure, but did not
properly initialize it when table ID 0 is used. This can lead to a route
in the default VRF with a preferred source address not being flushed
when the address is deleted.

Consider the following example:

# ip address add dev dummy1 192.0.2.1/28
# ip address add dev dummy1 192.0.2.17/28
# ip route add 198.51.100.0/24 via 192.0.2.2 src 192.0.2.17 metric 100
# ip route add table 0 198.51.100.0/24 via 192.0.2.2 src 192.0.2.17 metric 200
# ip route show 198.51.100.0/24
198.51.100.0/24 via 192.0.2.2 dev dummy1 src 192.0.2.17 metric 100
198.51.100.0/24 via 192.0.2.2 dev dummy1 src 192.0.2.17 metric 200

Both routes are installed in the default VRF, but they are using two
different FIB info structures. One with a metric of 100 and table ID of
254 (main) and one with a metric of 200 and table ID of 0. Therefore,
when the preferred source address is deleted from the default VRF,
the second route is not flushed:

# ip address del dev dummy1 192.0.2.17/28
# ip route show 198.51.100.0/24
198.51.100.0/24 via 192.0.2.2 dev dummy1 src 192.0.2.17 metric 200

Fix by storing a table ID of 254 instead of 0 in the route configuration
structure.

Add a test case that fails before the fix:

# ./fib_tests.sh -t ipv4_del_addr

IPv4 delete address route tests
Regular FIB info
TEST: Route removed from VRF when source address deleted [ OK ]
TEST: Route in default VRF not removed [ OK ]
TEST: Route removed in default VRF when source address deleted [ OK ]
TEST: Route in VRF is not removed by address delete [ OK ]
Identical FIB info with different table ID
TEST: Route removed from VRF when source address deleted [ OK ]
TEST: Route in default VRF not removed [ OK ]
TEST: Route removed in default VRF when source address deleted [ OK ]
TEST: Route in VRF is not removed by address delete [ OK ]
Table ID 0
TEST: Route removed in default VRF when source address deleted [FAIL]

Tests passed: 8
Tests failed: 1

And passes after:

# ./fib_tests.sh -t ipv4_del_addr

IPv4 delete address route tests
Regular FIB info
TEST: Route removed from VRF when source address deleted [ OK ]
TEST: Route in default VRF not removed [ OK ]
TEST: Route removed in default VRF when source address deleted [ OK ]
TEST: Route in VRF is not removed by address delete [ OK ]
Identical FIB info with different table ID
TEST: Route removed from VRF when source address deleted [ OK ]
TEST: Route in default VRF not removed [ OK ]
TEST: Route removed in default VRF when source address deleted [ OK ]
TEST: Route in VRF is not removed by address delete [ OK ]
Table ID 0
TEST: Route removed in default VRF when source address deleted [ OK ]

Tests passed: 9
Tests failed: 0

Fixes: 5a56a0b3a45d ("net: Don't delete routes in different VRFs")
Reported-by: Donald Sharp <sharpd@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/ipv4/fib_frontend.c | 3 +++
tools/testing/selftests/net/fib_tests.sh | 10 ++++++++++
2 files changed, 13 insertions(+)

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 943edf4ad4db..3528e8befa58 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -841,6 +841,9 @@ static int rtm_to_fib_config(struct net *net, struct sk_buff *skb,
return -EINVAL;
}

+ if (!cfg->fc_table)
+ cfg->fc_table = RT_TABLE_MAIN;
+
return 0;
errout:
return err;
diff --git a/tools/testing/selftests/net/fib_tests.sh b/tools/testing/selftests/net/fib_tests.sh
index 11c89148b19f..5637b5dadabd 100755
--- a/tools/testing/selftests/net/fib_tests.sh
+++ b/tools/testing/selftests/net/fib_tests.sh
@@ -1712,11 +1712,13 @@ ipv4_del_addr_test()
$IP addr add dev dummy1 172.16.104.1/24
$IP addr add dev dummy1 172.16.104.11/24
$IP addr add dev dummy1 172.16.104.12/24
+ $IP addr add dev dummy1 172.16.104.13/24
$IP addr add dev dummy2 172.16.104.1/24
$IP addr add dev dummy2 172.16.104.11/24
$IP addr add dev dummy2 172.16.104.12/24
$IP route add 172.16.105.0/24 via 172.16.104.2 src 172.16.104.11
$IP route add 172.16.106.0/24 dev lo src 172.16.104.12
+ $IP route add table 0 172.16.107.0/24 via 172.16.104.2 src 172.16.104.13
$IP route add vrf red 172.16.105.0/24 via 172.16.104.2 src 172.16.104.11
$IP route add vrf red 172.16.106.0/24 dev lo src 172.16.104.12
set +e
@@ -1762,6 +1764,14 @@ ipv4_del_addr_test()
$IP ro ls vrf red | grep -q 172.16.106.0/24
log_test $? 0 "Route in VRF is not removed by address delete"

+ # removing address from device in default vrf should remove route from
+ # the default vrf even when route was inserted with a table ID of 0.
+ echo " Table ID 0"
+
+ $IP addr del dev dummy1 172.16.104.13/24
+ $IP ro ls | grep -q 172.16.107.0/24
+ log_test $? 1 "Route removed in default VRF when source address deleted"
+
$IP li del dummy1
$IP li del dummy2
cleanup
--
2.35.1