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ipv6: clean up routes when manually removing address with a lifetime

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When an IPv6 address with a finite lifetime (configured with valid_lft
and preferred_lft) is manually deleted, the kernel does not clean up the
associated prefix route. This results in orphaned routes (marked "proto
kernel") remaining in the routing table even after their corresponding
address has been deleted.

This is particularly problematic on networks using combination of SLAAC
and bridges.

1. Machine comes up and performs RA on eth0.
2. User creates a bridge
   - does an ip -6 addr flush dev eth0;
   - adds the eth0 under the bridge.
3. SLAAC happens on br0.

Even tho the address has "moved" to br0 there will still be a route
pointing to eth0, but eth0 is not usable for IP any more.

Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20251113031700.3736285-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski
2025-11-12 19:17:00 -08:00
parent df58ee7d8f
commit c7dc5b5228
2 changed files with 21 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
net/ipv6/addrconf.c
View File

@@ -1324,7 +1324,7 @@ static void ipv6_del_addr(struct inet6_ifaddr *ifp)
__in6_ifa_put(ifp);
}
if (ifp->flags & IFA_F_PERMANENT && !(ifp->flags & IFA_F_NOPREFIXROUTE))
if (!(ifp->flags & IFA_F_NOPREFIXROUTE))
action = check_cleanup_prefix_route(ifp, &expires);
list_del_rcu(&ifp->if_list);

20
tools/testing/selftests/net/rtnetlink.sh
View File

@@ -8,6 +8,7 @@ ALL_TESTS="
kci_test_polrouting
kci_test_route_get
kci_test_addrlft
kci_test_addrlft_route_cleanup
kci_test_promote_secondaries
kci_test_tc
kci_test_gre
@@ -323,6 +324,25 @@ kci_test_addrlft()
end_test "PASS: preferred_lft addresses have expired"
}
kci_test_addrlft_route_cleanup()
{
local ret=0
local test_addr="2001:db8:99::1/64"
local test_prefix="2001:db8:99::/64"
run_cmd ip -6 addr add $test_addr dev "$devdummy" valid_lft 300 preferred_lft 300
run_cmd_grep "$test_prefix proto kernel" ip -6 route show dev "$devdummy"
run_cmd ip -6 addr del $test_addr dev "$devdummy"
run_cmd_grep_fail "$test_prefix" ip -6 route show dev "$devdummy"
if [ $ret -ne 0 ]; then
end_test "FAIL: route not cleaned up when address with valid_lft deleted"
return 1
fi
end_test "PASS: route cleaned up when address with valid_lft deleted"
}
kci_test_promote_secondaries()
{
run_cmd ifconfig "$devdummy"