ipsec: ipsec-input: check for too-short packets

Make sure packet is big enough before processing it.
Policy matching is done speculatively but is discarded if packet is too
short.

Type: fix

Change-Id: I647db2c4e568b0d9bf2cfd5056e1b1c2e25132fe
Signed-off-by: Benoît Ganne <bganne@cisco.com>

diff --git a/src/vnet/ipsec/ipsec_input.c b/src/vnet/ipsec/ipsec_input.c
index 9fdbff5..61b10fb 100644 (file)
--- a/src/vnet/ipsec/ipsec_input.c
+++ b/src/vnet/ipsec/ipsec_input.c
@@ -195,6 +195,7 @@ VLIB_NODE_FN (ipsec4_input_node) (vlib_main_t * vm,
          ip4_ipsec_config_t *c0;
          ipsec_spd_t *spd0;
          ipsec_policy_t *p0 = 0;
+         u8 has_space0;
 
          bi0 = to_next[0] = from[0];
          from += 1;
@@ -230,8 +231,7 @@ VLIB_NODE_FN (ipsec4_input_node) (vlib_main_t * vm,
                  esp0 =
                    (esp_header_t *) ((u8 *) esp0 + sizeof (udp_header_t));
                }
-             /* FIXME TODO missing check whether there is enough data inside
-              * IP/UDP to contain ESP header & stuff ? */
+
              p0 = ipsec_input_protect_policy_match (spd0,
                                                     clib_net_to_host_u32
                                                     (ip0->src_address.
@@ -242,7 +242,12 @@ VLIB_NODE_FN (ipsec4_input_node) (vlib_main_t * vm,
                                                     clib_net_to_host_u32
                                                     (esp0->spi));
 
-             if (PREDICT_TRUE (p0 != NULL))
+             has_space0 =
+               vlib_buffer_has_space (b0,
+                                      (clib_address_t) (esp0 + 1) -
+                                      (clib_address_t) ip0);
+
+             if (PREDICT_TRUE ((p0 != NULL) & (has_space0)))
                {
                  ipsec_matched += 1;
 
@@ -259,6 +264,7 @@ VLIB_NODE_FN (ipsec4_input_node) (vlib_main_t * vm,
                }
              else
                {
+                 p0 = 0;
                  pi0 = ~0;
                };
 
@@ -271,10 +277,11 @@ VLIB_NODE_FN (ipsec4_input_node) (vlib_main_t * vm,
                    vlib_add_trace (vm, node, b0, sizeof (*tr));
 
                  tr->proto = ip0->protocol;
-                 if (p0)
-                   tr->sa_id = p0->sa_id;
-                 tr->spi = clib_net_to_host_u32 (esp0->spi);
-                 tr->seq = clib_net_to_host_u32 (esp0->seq);
+                 tr->sa_id = p0 ? p0->sa_id : ~0;
+                 tr->spi =
+                   has_space0 ? clib_net_to_host_u32 (esp0->spi) : ~0;
+                 tr->seq =
+                   has_space0 ? clib_net_to_host_u32 (esp0->seq) : ~0;
                  tr->spd = spd0->id;
                  tr->policy_index = pi0;
                }
@@ -292,7 +299,12 @@ VLIB_NODE_FN (ipsec4_input_node) (vlib_main_t * vm,
                                                     clib_net_to_host_u32
                                                     (ah0->spi));
 
-             if (PREDICT_TRUE (p0 != 0))
+             has_space0 =
+               vlib_buffer_has_space (b0,
+                                      (clib_address_t) (ah0 + 1) -
+                                      (clib_address_t) ip0);
+
+             if (PREDICT_TRUE ((p0 != NULL) & (has_space0)))
                {
                  ipsec_matched += 1;
 
@@ -308,6 +320,7 @@ VLIB_NODE_FN (ipsec4_input_node) (vlib_main_t * vm,
                }
              else
                {
+                 p0 = 0;
                  pi0 = ~0;
                }
              /* FIXME bypass and discard */
@@ -319,10 +332,10 @@ VLIB_NODE_FN (ipsec4_input_node) (vlib_main_t * vm,
                    vlib_add_trace (vm, node, b0, sizeof (*tr));
 
                  tr->proto = ip0->protocol;
-                 if (p0)
-                   tr->sa_id = p0->sa_id;
-                 tr->spi = clib_net_to_host_u32 (ah0->spi);
-                 tr->seq = clib_net_to_host_u32 (ah0->seq_no);
+                 tr->sa_id = p0 ? p0->sa_id : ~0;
+                 tr->spi = has_space0 ? clib_net_to_host_u32 (ah0->spi) : ~0;
+                 tr->seq =
+                   has_space0 ? clib_net_to_host_u32 (ah0->seq_no) : ~0;
                  tr->spd = spd0->id;
                  tr->policy_index = pi0;
                }