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wireguard: fix crash by not sending arp via wg interface

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Type: fix

Currently, neighbor adjacencies on a wg interface are converted into a
midchain only if one of the peers has a matching allowed prefix
configured. If create a route that goes through a wg interface but the
next-hop address does not match any allowed prefixes, an ARP/ND request
will try to be sent via the wg interface to resolve the next-hop address
when matching traffic occurs. And sending an ARP request will cause VPP
to crash while copying hardware address of the wg interface which is
NULL. Sending an ND message will not cause VPP to crash but the error
logged will be unclear (no source address).

With this fix, convert all neighbor adjacencies on a wg interface into a
midchain and update tests to cover the case. If there is no matching
allowed prefix configured, traffic going such routes will be dropped
because of "Peer error". No changes if there is matching allowed prefix
configured.

Also, fix getting peer by adjacency index.

Signed-off-by: Alexander Chernavin <achernavin@netgate.com>
Change-Id: I15bc1e1f83de719e97edf3f7210a5359a35bddbd
This commit is contained in:
Alexander Chernavin
2022-06-02 09:55:37 +00:00
committed by Fan Zhang
parent db8dd260d5
commit 1477c7262a
3 changed files with 63 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
src/plugins/wireguard/wireguard_if.c
View File

@ -153,6 +153,14 @@ wg_if_update_adj (vnet_main_t * vnm, u32 sw_if_index, adj_index_t ai)
{
index_t wgii;
/* Convert any neighbour adjacency that has a next-hop reachable through
* the wg interface into a midchain. This is to avoid sending ARP/ND to
* resolve the next-hop address via the wg interface. Then, if one of the
* peers has matching prefix among allowed prefixes, the midchain will be
* updated to the corresponding one.
*/
adj_nbr_midchain_update_rewrite (ai, NULL, NULL, ADJ_FLAG_NONE, NULL);
wgii = wg_if_find_by_sw_if_index (sw_if_index);
wg_if_peer_walk (wg_if_get (wgii), wg_peer_if_adj_change, &ai);
}

2
src/plugins/wireguard/wireguard_peer.h
View File

@ -166,7 +166,7 @@ wg_peer_get (index_t peeri)
static inline index_t
wg_peer_get_by_adj_index (index_t ai)
{
if (ai > vec_len (wg_peer_by_adj_index))
if (ai >= vec_len (wg_peer_by_adj_index))
return INDEX_INVALID;
return (wg_peer_by_adj_index[ai]);
}

62
test/test_wireguard.py
View File

@ -392,10 +392,12 @@ class TestWg(VppTestCase):
wg6_input_node_name = "/err/wg6-input/"
kp4_error = wg4_output_node_name + "Keypair error"
mac4_error = wg4_input_node_name + "Invalid MAC handshake"
peer4_error = wg4_input_node_name + "Peer error"
peer4_in_err = wg4_input_node_name + "Peer error"
peer4_out_err = wg4_output_node_name + "Peer error"
kp6_error = wg6_output_node_name + "Keypair error"
mac6_error = wg6_input_node_name + "Invalid MAC handshake"
peer6_error = wg6_input_node_name + "Peer error"
peer6_in_err = wg6_input_node_name + "Peer error"
peer6_out_err = wg6_output_node_name + "Peer error"
@classmethod
def setUpClass(cls):
@ -421,10 +423,12 @@ class TestWg(VppTestCase):
super(VppTestCase, self).setUp()
self.base_kp4_err = self.statistics.get_err_counter(self.kp4_error)
self.base_mac4_err = self.statistics.get_err_counter(self.mac4_error)
self.base_peer4_err = self.statistics.get_err_counter(self.peer4_error)
self.base_peer4_in_err = self.statistics.get_err_counter(self.peer4_in_err)
self.base_peer4_out_err = self.statistics.get_err_counter(self.peer4_out_err)
self.base_kp6_err = self.statistics.get_err_counter(self.kp6_error)
self.base_mac6_err = self.statistics.get_err_counter(self.mac6_error)
self.base_peer6_err = self.statistics.get_err_counter(self.peer6_error)
self.base_peer6_in_err = self.statistics.get_err_counter(self.peer6_in_err)
self.base_peer6_out_err = self.statistics.get_err_counter(self.peer6_out_err)
def test_wg_interface(self):
"""Simple interface creation"""
@ -577,6 +581,9 @@ class TestWg(VppTestCase):
r1 = VppIpRoute(
self, "10.11.3.0", 24, [VppRoutePath("10.11.3.1", wg0.sw_if_index)]
).add_vpp_config()
r2 = VppIpRoute(
self, "20.22.3.0", 24, [VppRoutePath("20.22.3.1", wg0.sw_if_index)]
).add_vpp_config()
# route a packet into the wg interface
# use the allowed-ip prefix
@ -592,6 +599,21 @@ class TestWg(VppTestCase):
self.base_kp4_err + 1, self.statistics.get_err_counter(self.kp4_error)
)
# route a packet into the wg interface
# use a not allowed-ip prefix
# this is dropped because there is no matching peer
p = (
Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac)
/ IP(src=self.pg0.remote_ip4, dst="20.22.3.2")
/ UDP(sport=555, dport=556)
/ Raw()
)
self.send_and_assert_no_replies(self.pg0, [p])
self.assertEqual(
self.base_peer4_out_err + 1,
self.statistics.get_err_counter(self.peer4_out_err),
)
# send a handsake from the peer with an invalid MAC
p = peer_1.mk_handshake(self.pg1)
p[WireguardInitiation].mac1 = b"foobar"
@ -606,7 +628,8 @@ class TestWg(VppTestCase):
)
self.send_and_assert_no_replies(self.pg1, [p])
self.assertEqual(
self.base_peer4_err + 1, self.statistics.get_err_counter(self.peer4_error)
self.base_peer4_in_err + 1,
self.statistics.get_err_counter(self.peer4_in_err),
)
# send a valid handsake init for which we expect a response
@ -694,6 +717,7 @@ class TestWg(VppTestCase):
self.assertEqual(rx[IP].ttl, 19)
r1.remove_vpp_config()
r2.remove_vpp_config()
peer_1.remove_vpp_config()
wg0.remove_vpp_config()
@ -715,6 +739,9 @@ class TestWg(VppTestCase):
r1 = VppIpRoute(
self, "1::3:0", 112, [VppRoutePath("1::3:1", wg0.sw_if_index)]
).add_vpp_config()
r2 = VppIpRoute(
self, "22::3:0", 112, [VppRoutePath("22::3:1", wg0.sw_if_index)]
).add_vpp_config()
# route a packet into the wg interface
# use the allowed-ip prefix
@ -732,6 +759,21 @@ class TestWg(VppTestCase):
self.base_kp6_err + 1, self.statistics.get_err_counter(self.kp6_error)
)
# route a packet into the wg interface
# use a not allowed-ip prefix
# this is dropped because there is no matching peer
p = (
Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac)
/ IPv6(src=self.pg0.remote_ip6, dst="22::3:2")
/ UDP(sport=555, dport=556)
/ Raw()
)
self.send_and_assert_no_replies(self.pg0, [p])
self.assertEqual(
self.base_peer6_out_err + 1,
self.statistics.get_err_counter(self.peer6_out_err),
)
# send a handsake from the peer with an invalid MAC
p = peer_1.mk_handshake(self.pg1, True)
p[WireguardInitiation].mac1 = b"foobar"
@ -747,7 +789,8 @@ class TestWg(VppTestCase):
)
self.send_and_assert_no_replies(self.pg1, [p])
self.assertEqual(
self.base_peer6_err + 1, self.statistics.get_err_counter(self.peer6_error)
self.base_peer6_in_err + 1,
self.statistics.get_err_counter(self.peer6_in_err),
)
# send a valid handsake init for which we expect a response
@ -835,6 +878,7 @@ class TestWg(VppTestCase):
self.assertEqual(rx[IPv6].hlim, 19)
r1.remove_vpp_config()
r2.remove_vpp_config()
peer_1.remove_vpp_config()
wg0.remove_vpp_config()
@ -886,7 +930,8 @@ class TestWg(VppTestCase):
)
self.send_and_assert_no_replies(self.pg1, [p])
self.assertEqual(
self.base_peer4_err + 1, self.statistics.get_err_counter(self.peer4_error)
self.base_peer4_in_err + 1,
self.statistics.get_err_counter(self.peer4_in_err),
)
# send a valid handsake init for which we expect a response
@ -1024,7 +1069,8 @@ class TestWg(VppTestCase):
)
self.send_and_assert_no_replies(self.pg1, [p])
self.assertEqual(
self.base_peer6_err + 1, self.statistics.get_err_counter(self.peer6_error)
self.base_peer6_in_err + 1,
self.statistics.get_err_counter(self.peer6_in_err),
)
# send a valid handsake init for which we expect a response