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VPP-1522: harden reassembly code

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Change-Id: Ib5a20bff7d8a340ecf50bcd4a023d6bf36382ba3
Signed-off-by: Klement Sekera <ksekera@cisco.com>
This commit is contained in:
Klement Sekera
2018-12-10 13:46:09 +01:00
committed by Dave Barach
parent 69db1a6084
commit 14d7e90788
5 changed files with 85 additions and 43 deletions
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3
src/vnet/ip/ip4_error.h
View File

@ -86,7 +86,8 @@
/* Errors signalled by ip4-reassembly */ \
_ (REASS_DUPLICATE_FRAGMENT, "duplicate/overlapping fragments") \
_ (REASS_LIMIT_REACHED, "drops due to concurrent reassemblies limit") \
_ (REASS_TIMEOUT, "fragments dropped due to reassembly timeout")
_ (REASS_TIMEOUT, "fragments dropped due to reassembly timeout") \
_ (REASS_MALFORMED_PACKET, "malformed packets")
typedef enum
{

61
src/vnet/ip/ip4_reassembly.c
View File

@ -654,12 +654,12 @@ ip4_reass_update (vlib_main_t * vm, vlib_node_runtime_t * node,
ASSERT (fb->current_length >= sizeof (*fip));
vnet_buffer_opaque_t *fvnb = vnet_buffer (fb);
reass->next_index = fvnb->ip.reass.next_index; // store next_index before it's overwritten
u32 fragment_first = fvnb->ip.reass.fragment_first =
ip4_get_fragment_offset_bytes (fip);
u32 fragment_length =
const u32 fragment_first = ip4_get_fragment_offset_bytes (fip);
const u32 fragment_length =
clib_net_to_host_u16 (fip->length) - ip4_header_bytes (fip);
u32 fragment_last = fvnb->ip.reass.fragment_last =
fragment_first + fragment_length - 1;
const u32 fragment_last = fragment_first + fragment_length - 1;
fvnb->ip.reass.fragment_first = fragment_first;
fvnb->ip.reass.fragment_last = fragment_last;
int more_fragments = ip4_get_fragment_more (fip);
u32 candidate_range_bi = reass->first_bi;
u32 prev_range_bi = ~0;
@ -927,28 +927,43 @@ ip4_reassembly_inline (vlib_main_t * vm,
}
else
{
ip4_reass_key_t k;
k.as_u64[0] =
(u64) vnet_buffer (b0)->sw_if_index[VLIB_RX] << 32 | (u64)
ip0->src_address.as_u32;
k.as_u64[1] =
(u64) ip0->dst_address.
as_u32 << 32 | (u64) ip0->fragment_id << 16 | (u64) ip0->
protocol << 8;
ip4_reass_t *reass =
ip4_reass_find_or_create (vm, rm, rt, &k, &vec_drop_timeout);
if (reass)
ip4_header_t *fip = vlib_buffer_get_current (b0);
const u32 fragment_first = ip4_get_fragment_offset_bytes (fip);
const u32 fragment_length =
clib_net_to_host_u16 (fip->length) - ip4_header_bytes (fip);
const u32 fragment_last = fragment_first + fragment_length - 1;
if (fragment_first > fragment_last
|| fragment_first + fragment_length > UINT16_MAX - 20)
{
ip4_reass_update (vm, node, rm, rt, reass, &bi0, &next0,
&error0, &vec_drop_overlap,
&vec_drop_compress, is_feature);
next0 = IP4_REASSEMBLY_NEXT_DROP;
error0 = IP4_ERROR_REASS_MALFORMED_PACKET;
}
else
{
next0 = IP4_REASSEMBLY_NEXT_DROP;
error0 = IP4_ERROR_REASS_LIMIT_REACHED;
ip4_reass_key_t k;
k.as_u64[0] =
(u64) vnet_buffer (b0)->sw_if_index[VLIB_RX] << 32 | (u64)
ip0->src_address.as_u32;
k.as_u64[1] =
(u64) ip0->dst_address.
as_u32 << 32 | (u64) ip0->fragment_id << 16 | (u64) ip0->
protocol << 8;
ip4_reass_t *reass =
ip4_reass_find_or_create (vm, rm, rt, &k,
&vec_drop_timeout);
if (reass)
{
ip4_reass_update (vm, node, rm, rt, reass, &bi0, &next0,
&error0, &vec_drop_overlap,
&vec_drop_compress, is_feature);
}
else
{
next0 = IP4_REASSEMBLY_NEXT_DROP;
error0 = IP4_ERROR_REASS_LIMIT_REACHED;
}
}
b0->error = node->errors[error0];

21
test/framework.py
View File

@ -916,15 +916,18 @@ class VppTestCase(unittest.TestCase):
self.assert_checksum_valid(pkt, 'ICMPv6EchoReply', 'cksum')
def assert_packet_counter_equal(self, counter, expected_value):
counters = self.vapi.cli("sh errors").split('\n')
counter_value = -1
for i in range(1, len(counters)):
results = counters[i].split()
if results[1] == counter:
counter_value = int(results[0])
break
self.assert_equal(counter_value, expected_value,
"packet counter `%s'" % counter)
if counter.startswith("/"):
counter_value = self.statistics.get_counter(counter)
self.assert_equal(counter_value, expected_value,
"packet counter `%s'" % counter)
else:
counters = self.vapi.cli("sh errors").split('\n')
counter_value = -1
for i in range(1, len(counters) - 1):
results = counters[i].split()
if results[1] == counter:
counter_value = int(results[0])
break
@classmethod
def sleep(cls, timeout, remark=None):

12
test/template_ipsec.py
View File

@ -233,9 +233,8 @@ class IpsecTraTests(object):
seq_num=17))
self.send_and_assert_no_replies(self.tra_if, pkt * 17)
err = self.statistics.get_counter(
'/err/%s/SA replayed packet' % self.tra4_decrypt_node_name)
self.assertEqual(err, 17)
self.assert_packet_counter_equal(
'/err/%s/SA replayed packet' % self.tra4_decrypt_node_name, 17)
# a packet that does not decrypt does not move the window forward
bogus_sa = SecurityAssociation(self.encryption_type,
@ -248,9 +247,8 @@ class IpsecTraTests(object):
seq_num=350))
self.send_and_assert_no_replies(self.tra_if, pkt * 17)
err = self.statistics.get_counter(
'/err/%s/Integrity check failed' % self.tra4_decrypt_node_name)
self.assertEqual(err, 17)
self.assert_packet_counter_equal(
'/err/%s/Integrity check failed' % self.tra4_decrypt_node_name, 17)
# which we can determine since this packet is still in the window
pkt = (Ether(src=self.tra_if.remote_mac,
@ -259,7 +257,7 @@ class IpsecTraTests(object):
dst=self.tra_if.local_ip4) /
ICMP(),
seq_num=234))
recv_pkts = self.send_and_expect(self.tra_if, [pkt], self.tra_if)
self.send_and_expect(self.tra_if, [pkt], self.tra_if)
# move the security-associations seq number on to the last we used
p.scapy_tra_sa.seq_num = 351

31
test/test_reassembly.py
View File

@ -178,6 +178,31 @@ class TestIPv4Reassembly(VppTestCase):
self.verify_capture(packets)
self.src_if.assert_nothing_captured()
def test_5737(self):
""" fragment length + ip header size > 65535 """
raw = ('E\x00\x00\x88,\xf8\x1f\xfe@\x01\x98\x00\xc0\xa8\n-\xc0\xa8\n'
'\x01\x08\x00\xf0J\xed\xcb\xf1\xf5Test-group: IPv4.IPv4.ipv4-'
'message.Ethernet-Payload.IPv4-Packet.IPv4-Header.Fragment-Of'
'fset; Test-case: 5737')
malformed_packet = (Ether(dst=self.src_if.local_mac,
src=self.src_if.remote_mac) /
IP(raw))
p = (Ether(dst=self.src_if.local_mac, src=self.src_if.remote_mac) /
IP(id=1000, src=self.src_if.remote_ip4,
dst=self.dst_if.remote_ip4) /
UDP(sport=1234, dport=5678) /
Raw("X" * 1000))
valid_fragments = fragment_rfc791(p, 400)
self.pg_enable_capture()
self.src_if.add_stream([malformed_packet] + valid_fragments)
self.pg_start()
self.dst_if.get_capture(1)
self.assert_packet_counter_equal(
"/err/ip4-reassembly-feature/malformed packets", 1)
@unittest.skipIf(is_skip_aarch64_set() and is_platform_aarch64(),
"test doesn't work on aarch64")
def test_random(self):
@ -838,7 +863,7 @@ class TestIPv4ReassemblyLocalNode(VppTestCase):
seen.add(packet_index)
self.assertEqual(payload_info.dst, self.src_dst_if.sw_if_index)
info = self._packet_infos[packet_index]
self.assertTrue(info is not None)
self.assertIsNotNone(info)
self.assertEqual(packet_index, info.index)
saved_packet = info.data
self.assertEqual(ip.src, saved_packet[IP].dst)
@ -850,8 +875,8 @@ class TestIPv4ReassemblyLocalNode(VppTestCase):
self.logger.error(ppp("Unexpected or invalid packet:", packet))
raise
for index in self._packet_infos:
self.assertTrue(index in seen or index in dropped_packet_indexes,
"Packet with packet_index %d not received" % index)
self.assertIn(index, seen,
"Packet with packet_index %d not received" % index)
def test_reassembly(self):
""" basic reassembly """