commit a829b13986d556ab3aeb52668129fe4b13a1f24f
author Damjan Marion <damarion@cisco.com> Wed Apr 24 23:39:16 2019 +0200
committer Damjan Marion <dmarion@me.com> Thu Apr 25 08:32:28 2019 +0000
tree 157e7c2deea5405c97b9c80f40f773c43d453cb8
parent d1bed687231bb64cf7761da37431ba61bc32b6d8

ipsec: drop runts in esp-decrypt

Change-Id: Id7fcaf8590f9f2dcccdebea0ad31c7ecd1cbc8af
Signed-off-by: Damjan Marion <damarion@cisco.com>

src/vnet/ipsec/esp_decrypt.c

diff --git a/src/vnet/ipsec/esp_decrypt.c b/src/vnet/ipsec/esp_decrypt.c
index 5d1f206..dfc86d4 100644
--- a/src/vnet/ipsec/esp_decrypt.c
+++ b/src/vnet/ipsec/esp_decrypt.c
@@ -44,6 +44,7 @@
  _(INTEG_ERROR, "Integrity check failed")                       \
  _(CRYPTO_ENGINE_ERROR, "crypto engine error (packet dropped)") \
  _(REPLAY, "SA replayed packet")                                \
+ _(RUNT, "undersized packet")                                   \
  _(CHAINED_BUFFER, "chained buffers (packet dropped)")          \
  _(OVERSIZED_HEADER, "buffer with oversized header (dropped)")  \
  _(NO_TAIL_SPACE, "no enough buffer tail space (dropped)")
@@ -193,6 +194,13 @@
 	  goto next;
 	}
 
+      if (pd->current_length < cpd.icv_sz + esp_sz + cpd.iv_sz)
+	{
+	  b[0]->error = node->errors[ESP_DECRYPT_ERROR_RUNT];
+	  next[0] = ESP_DECRYPT_NEXT_DROP;
+	  goto next;
+	}
+
       len = pd->current_length - cpd.icv_sz;
       current_sa_pkts += 1;
       current_sa_bytes += pd->current_length;

test/template_ipsec.py

diff --git a/test/template_ipsec.py b/test/template_ipsec.py
index 3a97820..c623d6a 100644
--- a/test/template_ipsec.py
+++ b/test/template_ipsec.py
@@ -3,7 +3,7 @@
 import struct
 
 from scapy.layers.inet import IP, ICMP, TCP, UDP
-from scapy.layers.ipsec import SecurityAssociation
+from scapy.layers.ipsec import SecurityAssociation, ESP
 from scapy.layers.l2 import Ether, Raw
 from scapy.layers.inet6 import IPv6, ICMPv6EchoRequest
 
@@ -308,7 +308,11 @@
 
         # a packet that does not decrypt does not move the window forward
         bogus_sa = SecurityAssociation(self.encryption_type,
-                                       p.vpp_tra_spi)
+                                       p.vpp_tra_spi,
+                                       crypt_algo=p.crypt_algo,
+                                       crypt_key=p.crypt_key[::-1],
+                                       auth_algo=p.auth_algo,
+                                       auth_key=p.auth_key[::-1])
         pkt = (Ether(src=self.tra_if.remote_mac,
                      dst=self.tra_if.local_mac) /
                bogus_sa.encrypt(IP(src=self.tra_if.remote_ip4,
@@ -320,6 +324,22 @@
         self.assert_packet_counter_equal(
             '/err/%s/Integrity check failed' % self.tra4_decrypt_node_name, 17)
 
+        # a malformed 'runt' packet
+        #  created by a mis-constructed SA
+        if (ESP == self.encryption_type):
+            bogus_sa = SecurityAssociation(self.encryption_type,
+                                           p.vpp_tra_spi)
+            pkt = (Ether(src=self.tra_if.remote_mac,
+                         dst=self.tra_if.local_mac) /
+                   bogus_sa.encrypt(IP(src=self.tra_if.remote_ip4,
+                                       dst=self.tra_if.local_ip4) /
+                                    ICMP(),
+                                    seq_num=350))
+            self.send_and_assert_no_replies(self.tra_if, pkt * 17)
+
+            self.assert_packet_counter_equal(
+                '/err/%s/undersized packet' % 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,
                      dst=self.tra_if.local_mac) /