[PATCH 5.4 61/67] ipv4: Fix incorrect route flushing when table ID 0 is used

Greg Kroah-Hartman
2022-12-12T13:23:52Z

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 +++
1 file changed, 3 insertions(+)

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index d38c8ca93ba0..be31eeacb0be 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -840,6 +840,9 @@ 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;
--
2.35.1