ipsec: fix l2 header handling in ah encrypt

Use proper length for copying l2 layer in ah encrypt code. Previously
code assumed that there is alywas just one ethernet header preceding IP
header, which might not be true always.

Change-Id: I176fd93b25cf1b9d9c2dc4e420ad48a94d5f4fb8
Ticket: VPP-1539
Type: fix
Fixes: N/A
Signed-off-by: Klement Sekera <ksekera@cisco.com>

diff --git a/src/vnet/ipsec/ah_encrypt.c b/src/vnet/ipsec/ah_encrypt.c
index d12ca67..1be4b3a 100644 (file)
--- a/src/vnet/ipsec/ah_encrypt.c
+++ b/src/vnet/ipsec/ah_encrypt.c
@@ -216,12 +216,12 @@ ah_encrypt_inline (vlib_main_t * vm,
       /* transport mode save the eth header before it is overwritten */
       if (PREDICT_FALSE (!ipsec_sa_is_set_IS_TUNNEL (sa0)))
        {
-         ethernet_header_t *ieh0 = (ethernet_header_t *)
-           ((u8 *) vlib_buffer_get_current (b[0]) -
-            sizeof (ethernet_header_t));
-         ethernet_header_t *oeh0 =
-           (ethernet_header_t *) ((u8 *) ieh0 + (adv - icv_size));
-         clib_memcpy_fast (oeh0, ieh0, sizeof (ethernet_header_t));
+         const u32 l2_len = vnet_buffer (b[0])->ip.save_rewrite_length;
+         u8 *l2_hdr_in = (u8 *) vlib_buffer_get_current (b[0]) - l2_len;
+
+         u8 *l2_hdr_out = l2_hdr_in + adv - icv_size;
+
+         clib_memcpy_le32 (l2_hdr_out, l2_hdr_in, l2_len);
        }
 
       vlib_buffer_advance (b[0], adv - icv_size);