ipsec: add support for chained buffers
[vpp.git] / src / vnet / ipsec / esp_decrypt.c
index 56724c0..f29dacb 100644 (file)
@@ -50,7 +50,7 @@ typedef enum
  _(CRYPTO_ENGINE_ERROR, "crypto engine error (packet dropped)") \
  _(REPLAY, "SA replayed packet")                                \
  _(RUNT, "undersized packet")                                   \
- _(CHAINED_BUFFER, "chained buffers (packet dropped)")          \
+ _(NO_BUFFERS, "no buffers (packet dropped)")                   \
  _(OVERSIZED_HEADER, "buffer with oversized header (dropped)")  \
  _(NO_TAIL_SPACE, "no enough buffer tail space (dropped)")      \
  _(TUN_NO_PROTO, "no tunnel protocol")                          \
@@ -114,12 +114,130 @@ typedef struct
   i16 current_data;
   i16 current_length;
   u16 hdr_sz;
+  vlib_buffer_t *lb;
+  u32 free_buffer_index;
+  u8 icv_removed;
 } esp_decrypt_packet_data_t;
 
-STATIC_ASSERT_SIZEOF (esp_decrypt_packet_data_t, 3 * sizeof (u64));
+STATIC_ASSERT_SIZEOF (esp_decrypt_packet_data_t, 5 * sizeof (u64));
 
 #define ESP_ENCRYPT_PD_F_FD_TRANSPORT (1 << 2)
 
+static_always_inline void
+esp_process_ops (vlib_main_t * vm, vlib_node_runtime_t * node,
+                vnet_crypto_op_t * ops, vlib_buffer_t * b[], u16 * nexts,
+                int e)
+{
+  vnet_crypto_op_t *op = ops;
+  u32 n_fail, n_ops = vec_len (ops);
+
+  if (n_ops == 0)
+    return;
+
+  n_fail = n_ops - vnet_crypto_process_ops (vm, op, n_ops);
+
+  while (n_fail)
+    {
+      ASSERT (op - ops < n_ops);
+      if (op->status != VNET_CRYPTO_OP_STATUS_COMPLETED)
+       {
+         u32 err, bi = op->user_data;
+         if (op->status == VNET_CRYPTO_OP_STATUS_FAIL_BAD_HMAC)
+           err = e;
+         else
+           err = ESP_DECRYPT_ERROR_CRYPTO_ENGINE_ERROR;
+         b[bi]->error = node->errors[err];
+         nexts[bi] = ESP_DECRYPT_NEXT_DROP;
+         n_fail--;
+       }
+      op++;
+    }
+}
+
+static_always_inline void
+esp_process_chained_ops (vlib_main_t * vm, vlib_node_runtime_t * node,
+                        vnet_crypto_op_t * ops, vlib_buffer_t * b[],
+                        u16 * nexts, vnet_crypto_op_chunk_t * chunks, int e)
+{
+
+  vnet_crypto_op_t *op = ops;
+  u32 n_fail, n_ops = vec_len (ops);
+
+  if (n_ops == 0)
+    return;
+
+  n_fail = n_ops - vnet_crypto_process_chained_ops (vm, op, chunks, n_ops);
+
+  while (n_fail)
+    {
+      ASSERT (op - ops < n_ops);
+      if (op->status != VNET_CRYPTO_OP_STATUS_COMPLETED)
+       {
+         u32 err, bi = op->user_data;
+         if (op->status == VNET_CRYPTO_OP_STATUS_FAIL_BAD_HMAC)
+           err = e;
+         else
+           err = ESP_DECRYPT_ERROR_CRYPTO_ENGINE_ERROR;
+         b[bi]->error = node->errors[err];
+         nexts[bi] = ESP_DECRYPT_NEXT_DROP;
+         n_fail--;
+       }
+      op++;
+    }
+}
+
+always_inline void
+esp_remove_tail (vlib_main_t * vm, vlib_buffer_t * b, vlib_buffer_t * last,
+                u16 tail)
+{
+  vlib_buffer_t *before_last = b;
+
+  if (last->current_length > tail)
+    {
+      last->current_length -= tail;
+      return;
+    }
+  ASSERT (b->flags & VLIB_BUFFER_NEXT_PRESENT);
+
+  while (b->flags & VLIB_BUFFER_NEXT_PRESENT)
+    {
+      before_last = b;
+      b = vlib_get_buffer (vm, b->next_buffer);
+    }
+  before_last->current_length -= tail - last->current_length;
+  vlib_buffer_free_one (vm, before_last->next_buffer);
+  before_last->flags &= ~VLIB_BUFFER_NEXT_PRESENT;
+}
+
+/* ICV is splitted in last two buffers so move it to the last buffer and
+   return pointer to it */
+static_always_inline u8 *
+esp_move_icv (vlib_main_t * vm, vlib_buffer_t * first,
+             esp_decrypt_packet_data_t * pd, u16 icv_sz)
+{
+  vlib_buffer_t *before_last, *bp;
+  u16 last_sz = pd->lb->current_length;
+  u16 first_sz = icv_sz - last_sz;
+
+  bp = before_last = first;
+  while (bp->flags & VLIB_BUFFER_NEXT_PRESENT)
+    {
+      before_last = bp;
+      bp = vlib_get_buffer (vm, bp->next_buffer);
+    }
+
+  u8 *lb_curr = vlib_buffer_get_current (pd->lb);
+  memmove (lb_curr + first_sz, lb_curr, last_sz);
+  clib_memcpy_fast (lb_curr, vlib_buffer_get_tail (before_last) - first_sz,
+                   first_sz);
+  before_last->current_length -= first_sz;
+  pd->lb = before_last;
+  pd->icv_removed = 1;
+  pd->free_buffer_index = before_last->next_buffer;
+  before_last->flags &= ~VLIB_BUFFER_NEXT_PRESENT;
+  return lb_curr;
+}
+
 always_inline uword
 esp_decrypt_inline (vlib_main_t * vm,
                    vlib_node_runtime_t * node, vlib_frame_t * from_frame,
@@ -131,7 +249,7 @@ esp_decrypt_inline (vlib_main_t * vm,
   u16 len;
   ipsec_per_thread_data_t *ptd = vec_elt_at_index (im->ptd, thread_index);
   u32 *from = vlib_frame_vector_args (from_frame);
-  u32 n, n_left = from_frame->n_vectors;
+  u32 n_left = from_frame->n_vectors;
   vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b = bufs;
   u16 nexts[VLIB_FRAME_SIZE], *next = nexts;
   esp_decrypt_packet_data_t pkt_data[VLIB_FRAME_SIZE], *pd = pkt_data;
@@ -139,10 +257,16 @@ esp_decrypt_inline (vlib_main_t * vm,
   u32 current_sa_index = ~0, current_sa_bytes = 0, current_sa_pkts = 0;
   const u8 esp_sz = sizeof (esp_header_t);
   ipsec_sa_t *sa0 = 0;
+  vnet_crypto_op_chunk_t *ch;
+  vnet_crypto_op_t **crypto_ops = &ptd->crypto_ops;
+  vnet_crypto_op_t **integ_ops = &ptd->integ_ops;
 
   vlib_get_buffers (vm, from, b, n_left);
   vec_reset_length (ptd->crypto_ops);
   vec_reset_length (ptd->integ_ops);
+  vec_reset_length (ptd->chained_crypto_ops);
+  vec_reset_length (ptd->chained_integ_ops);
+  vec_reset_length (ptd->chunks);
   clib_memset_u16 (nexts, -1, n_left);
 
   while (n_left > 0)
@@ -159,9 +283,10 @@ esp_decrypt_inline (vlib_main_t * vm,
          CLIB_PREFETCH (p, CLIB_CACHE_LINE_BYTES, LOAD);
        }
 
-      if (vlib_buffer_chain_linearize (vm, b[0]) != 1)
+      u32 n_bufs = vlib_buffer_chain_linearize (vm, b[0]);
+      if (n_bufs == 0)
        {
-         b[0]->error = node->errors[ESP_DECRYPT_ERROR_CHAINED_BUFFER];
+         b[0]->error = node->errors[ESP_DECRYPT_ERROR_NO_BUFFERS];
          next[0] = ESP_DECRYPT_NEXT_DROP;
          goto next;
        }
@@ -205,10 +330,26 @@ esp_decrypt_inline (vlib_main_t * vm,
       pd->hdr_sz = pd->current_data - vnet_buffer (b[0])->l3_hdr_offset;
       payload = b[0]->data + pd->current_data;
       pd->seq = clib_host_to_net_u32 (((esp_header_t *) payload)->seq);
+      pd->free_buffer_index = 0;
+      pd->icv_removed = 0;
+
+      pd->lb = b[0];
+      if (n_bufs > 1)
+       {
+         /* find last buffer in the chain */
+         while (pd->lb->flags & VLIB_BUFFER_NEXT_PRESENT)
+           pd->lb = vlib_get_buffer (vm, pd->lb->next_buffer);
+
+         crypto_ops = &ptd->chained_crypto_ops;
+         integ_ops = &ptd->chained_integ_ops;
+       }
+      pd->current_length = b[0]->current_length;
 
       /* we need 4 extra bytes for HMAC calculation when ESN are used */
-      if (ipsec_sa_is_set_USE_ESN (sa0) && pd->icv_sz &&
-         (pd->current_data + pd->current_length + 4 > buffer_data_size))
+      /* Chained buffers can process ESN as a separate chunk */
+      if (pd->lb == b[0] && ipsec_sa_is_set_USE_ESN (sa0) && cpd.icv_sz &&
+         (pd->lb->current_data + pd->lb->current_length + 4
+          > buffer_data_size))
        {
          b[0]->error = node->errors[ESP_DECRYPT_ERROR_NO_TAIL_SPACE];
          next[0] = ESP_DECRYPT_NEXT_DROP;
@@ -232,12 +373,12 @@ esp_decrypt_inline (vlib_main_t * vm,
 
       len = pd->current_length - cpd.icv_sz;
       current_sa_pkts += 1;
-      current_sa_bytes += pd->current_length;
+      current_sa_bytes += vlib_buffer_length_in_chain (vm, b[0]);
 
       if (PREDICT_TRUE (sa0->integ_op_id != VNET_CRYPTO_OP_NONE))
        {
          vnet_crypto_op_t *op;
-         vec_add2_aligned (ptd->integ_ops, op, 1, CLIB_CACHE_LINE_BYTES);
+         vec_add2_aligned (integ_ops[0], op, 1, CLIB_CACHE_LINE_BYTES);
 
          vnet_crypto_op_init (op, sa0->integ_op_id);
          op->key_index = sa0->integ_key_index;
@@ -247,7 +388,100 @@ esp_decrypt_inline (vlib_main_t * vm,
          op->digest = payload + len;
          op->digest_len = cpd.icv_sz;
          op->len = len;
-         if (ipsec_sa_is_set_USE_ESN (sa0))
+
+         if (pd->lb != b[0])
+           {
+             /* buffer is chained */
+             vlib_buffer_t *cb = b[0];
+             op->flags |= VNET_CRYPTO_OP_FLAG_CHAINED_BUFFERS;
+             op->chunk_index = vec_len (ptd->chunks);
+
+             if (pd->lb->current_length < cpd.icv_sz)
+               op->digest = esp_move_icv (vm, b[0], pd, cpd.icv_sz);
+             else
+               op->digest = vlib_buffer_get_tail (pd->lb) - cpd.icv_sz;
+
+             vec_add2 (ptd->chunks, ch, 1);
+             ch->len = pd->current_length;
+             ch->src = payload;
+             cb = vlib_get_buffer (vm, cb->next_buffer);
+             op->n_chunks = 1;
+             while (1)
+               {
+                 vec_add2 (ptd->chunks, ch, 1);
+                 op->n_chunks += 1;
+                 ch->src = vlib_buffer_get_current (cb);
+                 if (pd->lb == cb)
+                   {
+                     if (pd->icv_removed)
+                       ch->len = cb->current_length;
+                     else
+                       ch->len = cb->current_length - cpd.icv_sz;
+                     if (ipsec_sa_is_set_USE_ESN (sa0))
+                       {
+                         u32 seq_hi = clib_host_to_net_u32 (sa0->seq_hi);
+                         u8 tmp[ESP_MAX_ICV_SIZE], sz = sizeof (sa0->seq_hi);
+                         u8 *esn;
+                         vlib_buffer_t *tmp_b;
+                         u16 space_left = vlib_buffer_space_left_at_end
+                           (vm, pd->lb);
+                         if (space_left < sz)
+                           {
+                             if (pd->icv_removed)
+                               {
+                                 /* use pre-data area from the last bufer
+                                    that was removed from the chain */
+                                 tmp_b =
+                                   vlib_get_buffer (vm,
+                                                    pd->free_buffer_index);
+                                 esn = tmp_b->data - sz;
+                               }
+                             else
+                               {
+                                 /* no space, need to allocate new buffer */
+                                 u32 tmp_bi = 0;
+                                 vlib_buffer_alloc (vm, &tmp_bi, 1);
+                                 tmp_b = vlib_get_buffer (vm, tmp_bi);
+                                 esn = tmp_b->data;
+                                 pd->free_buffer_index = tmp_bi;
+                               }
+                             clib_memcpy_fast (esn, &seq_hi, sz);
+
+                             vec_add2 (ptd->chunks, ch, 1);
+                             op->n_chunks += 1;
+                             ch->src = esn;
+                             ch->len = sz;
+                           }
+                         else
+                           {
+                             if (pd->icv_removed)
+                               {
+                                 clib_memcpy_fast (vlib_buffer_get_tail
+                                                   (pd->lb), &seq_hi, sz);
+                               }
+                             else
+                               {
+                                 clib_memcpy_fast (tmp, op->digest,
+                                                   ESP_MAX_ICV_SIZE);
+                                 clib_memcpy_fast (op->digest, &seq_hi, sz);
+                                 clib_memcpy_fast (op->digest + sz, tmp,
+                                                   ESP_MAX_ICV_SIZE);
+                                 op->digest += sz;
+                               }
+                             ch->len += sz;
+                           }
+                       }
+                   }
+                 else
+                   ch->len = cb->current_length;
+
+                 if (!(cb->flags & VLIB_BUFFER_NEXT_PRESENT))
+                   break;
+
+                 cb = vlib_get_buffer (vm, cb->next_buffer);
+               }
+           }
+         else if (ipsec_sa_is_set_USE_ESN (sa0))
            {
              /* shift ICV by 4 bytes to insert ESN */
              u32 seq_hi = clib_host_to_net_u32 (sa0->seq_hi);
@@ -263,10 +497,10 @@ esp_decrypt_inline (vlib_main_t * vm,
       payload += esp_sz;
       len -= esp_sz;
 
-      if (sa0->crypto_enc_op_id != VNET_CRYPTO_OP_NONE)
+      if (sa0->crypto_dec_op_id != VNET_CRYPTO_OP_NONE)
        {
          vnet_crypto_op_t *op;
-         vec_add2_aligned (ptd->crypto_ops, op, 1, CLIB_CACHE_LINE_BYTES);
+         vec_add2_aligned (crypto_ops[0], op, 1, CLIB_CACHE_LINE_BYTES);
          vnet_crypto_op_init (op, sa0->crypto_dec_op_id);
          op->key_index = sa0->crypto_key_index;
          op->iv = payload;
@@ -303,6 +537,61 @@ esp_decrypt_inline (vlib_main_t * vm,
          op->src = op->dst = payload += cpd.iv_sz;
          op->len = len - cpd.iv_sz;
          op->user_data = b - bufs;
+
+         if (pd->lb != b[0])
+           {
+             /* buffer is chained */
+             vlib_buffer_t *cb = b[0];
+             op->flags |= VNET_CRYPTO_OP_FLAG_CHAINED_BUFFERS;
+             op->chunk_index = vec_len (ptd->chunks);
+             vec_add2 (ptd->chunks, ch, 1);
+             ch->len = len - cpd.iv_sz + cpd.icv_sz;
+             ch->src = ch->dst = payload;
+             cb = vlib_get_buffer (vm, cb->next_buffer);
+             op->n_chunks = 1;
+
+             while (1)
+               {
+                 vec_add2 (ptd->chunks, ch, 1);
+                 op->n_chunks += 1;
+                 ch->src = ch->dst = vlib_buffer_get_current (cb);
+                 if (pd->lb == cb)
+                   {
+                     if (ipsec_sa_is_set_IS_AEAD (sa0))
+                       {
+                         if (pd->lb->current_length < cpd.icv_sz)
+                           {
+                             op->tag =
+                               esp_move_icv (vm, b[0], pd, cpd.icv_sz);
+
+                             /* this chunk does not contain crypto data */
+                             op->n_chunks -= 1;
+
+                             /* and fix previous chunk's length as it might have
+                                been changed */
+                             ASSERT (op->n_chunks > 0);
+                             ch[-1].len = pd->lb->current_length;
+                             break;
+                           }
+                         else
+                           op->tag =
+                             vlib_buffer_get_tail (pd->lb) - cpd.icv_sz;
+                       }
+
+                     if (pd->icv_removed)
+                       ch->len = cb->current_length;
+                     else
+                       ch->len = cb->current_length - cpd.icv_sz;
+                   }
+                 else
+                   ch->len = cb->current_length;
+
+                 if (!(cb->flags & VLIB_BUFFER_NEXT_PRESENT))
+                   break;
+
+                 cb = vlib_get_buffer (vm, cb->next_buffer);
+               }
+           }
        }
 
       /* next */
@@ -318,52 +607,15 @@ esp_decrypt_inline (vlib_main_t * vm,
                                     current_sa_index, current_sa_pkts,
                                     current_sa_bytes);
 
-  if ((n = vec_len (ptd->integ_ops)))
-    {
-      vnet_crypto_op_t *op = ptd->integ_ops;
-      n -= vnet_crypto_process_ops (vm, op, n);
-      while (n)
-       {
-         ASSERT (op - ptd->integ_ops < vec_len (ptd->integ_ops));
-         if (op->status != VNET_CRYPTO_OP_STATUS_COMPLETED)
-           {
-             u32 err, bi = op->user_data;
-             if (op->status == VNET_CRYPTO_OP_STATUS_FAIL_BAD_HMAC)
-               err = ESP_DECRYPT_ERROR_INTEG_ERROR;
-             else
-               err = ESP_DECRYPT_ERROR_CRYPTO_ENGINE_ERROR;
-             bufs[bi]->error = node->errors[err];
-             nexts[bi] = ESP_DECRYPT_NEXT_DROP;
-             n--;
-           }
-         op++;
-       }
-    }
-  if ((n = vec_len (ptd->crypto_ops)))
-    {
-      vnet_crypto_op_t *op = ptd->crypto_ops;
-      n -= vnet_crypto_process_ops (vm, op, n);
-      while (n)
-       {
-         ASSERT (op - ptd->crypto_ops < vec_len (ptd->crypto_ops));
-         if (op->status != VNET_CRYPTO_OP_STATUS_COMPLETED)
-           {
-             u32 err, bi;
-
-             bi = op->user_data;
-
-             if (op->status == VNET_CRYPTO_OP_STATUS_FAIL_BAD_HMAC)
-               err = ESP_DECRYPT_ERROR_DECRYPTION_FAILED;
-             else
-               err = ESP_DECRYPT_ERROR_CRYPTO_ENGINE_ERROR;
+  esp_process_ops (vm, node, ptd->integ_ops, bufs, nexts,
+                  ESP_DECRYPT_ERROR_INTEG_ERROR);
+  esp_process_chained_ops (vm, node, ptd->chained_integ_ops, bufs, nexts,
+                          ptd->chunks, ESP_DECRYPT_ERROR_INTEG_ERROR);
 
-             bufs[bi]->error = node->errors[err];
-             nexts[bi] = ESP_DECRYPT_NEXT_DROP;
-             n--;
-           }
-         op++;
-       }
-    }
+  esp_process_ops (vm, node, ptd->crypto_ops, bufs, nexts,
+                  ESP_DECRYPT_ERROR_DECRYPTION_FAILED);
+  esp_process_chained_ops (vm, node, ptd->chained_crypto_ops, bufs, nexts,
+                          ptd->chunks, ESP_DECRYPT_ERROR_DECRYPTION_FAILED);
 
   /* Post decryption ronud - adjust packet data start and length and next
      node */
@@ -430,11 +682,51 @@ esp_decrypt_inline (vlib_main_t * vm,
 
       ipsec_sa_anti_replay_advance (sa0, pd->seq);
 
-      esp_footer_t *f = (esp_footer_t *) (b[0]->data + pd->current_data +
-                                         pd->current_length - sizeof (*f) -
-                                         pd->icv_sz);
+      u8 pad_length = 0, next_header = 0;
+      u16 icv_sz = pd->icv_removed ? 0 : pd->icv_sz;
+
+      if (pd->free_buffer_index)
+       vlib_buffer_free_one (vm, pd->free_buffer_index);
+
+      if (pd->lb->current_length < sizeof (esp_footer_t) + icv_sz)
+       {
+         /* esp footer is either splitted in two buffers or in the before
+          * last buffer */
+
+         vlib_buffer_t *before_last = b[0], *bp = b[0];
+         while (bp->flags & VLIB_BUFFER_NEXT_PRESENT)
+           {
+             before_last = bp;
+             bp = vlib_get_buffer (vm, bp->next_buffer);
+           }
+         u8 *bt = vlib_buffer_get_tail (before_last);
+
+         if (pd->lb->current_length == icv_sz)
+           {
+             esp_footer_t *f = (esp_footer_t *) (bt - sizeof (*f));
+             pad_length = f->pad_length;
+             next_header = f->next_header;
+           }
+         else
+           {
+             pad_length = (bt - 1)[0];
+             next_header = ((u8 *) vlib_buffer_get_current (pd->lb))[0];
+           }
+       }
+      else
+       {
+         esp_footer_t *f =
+           (esp_footer_t *) (pd->lb->data + pd->lb->current_data +
+                             pd->lb->current_length - sizeof (esp_footer_t) -
+                             icv_sz);
+         pad_length = f->pad_length;
+         next_header = f->next_header;
+       }
+
       u16 adv = pd->iv_sz + esp_sz;
-      u16 tail = sizeof (esp_footer_t) + f->pad_length + pd->icv_sz;
+      u16 tail = sizeof (esp_footer_t) + pad_length + icv_sz;
+      u16 tail_orig = sizeof (esp_footer_t) + pad_length + pd->icv_sz;
+      b[0]->flags &= ~VLIB_BUFFER_TOTAL_LENGTH_VALID;
 
       if ((pd->flags & tun_flags) == 0 && !is_tun)     /* transport mode */
        {
@@ -450,15 +742,16 @@ esp_decrypt_inline (vlib_main_t * vm,
            clib_memcpy_le64 (ip, old_ip, ip_hdr_sz);
 
          b[0]->current_data = pd->current_data + adv - ip_hdr_sz;
-         b[0]->current_length = pd->current_length + ip_hdr_sz - tail - adv;
+         b[0]->current_length = pd->current_length + ip_hdr_sz - adv;
+         esp_remove_tail (vm, b[0], pd->lb, tail);
 
          if (is_ip6)
            {
              ip6_header_t *ip6 = (ip6_header_t *) ip;
              u16 len = clib_net_to_host_u16 (ip6->payload_length);
-             len -= adv + tail;
+             len -= adv + tail_orig;
              ip6->payload_length = clib_host_to_net_u16 (len);
-             ip6->protocol = f->next_header;
+             ip6->protocol = next_header;
              next[0] = ESP_DECRYPT_NEXT_IP6_INPUT;
            }
          else
@@ -466,34 +759,36 @@ esp_decrypt_inline (vlib_main_t * vm,
              ip4_header_t *ip4 = (ip4_header_t *) ip;
              ip_csum_t sum = ip4->checksum;
              u16 len = clib_net_to_host_u16 (ip4->length);
-             len = clib_host_to_net_u16 (len - adv - tail - udp_sz);
-             sum = ip_csum_update (sum, ip4->protocol, f->next_header,
+             len = clib_host_to_net_u16 (len - adv - tail_orig - udp_sz);
+             sum = ip_csum_update (sum, ip4->protocol, next_header,
                                    ip4_header_t, protocol);
              sum = ip_csum_update (sum, ip4->length, len,
                                    ip4_header_t, length);
              ip4->checksum = ip_csum_fold (sum);
-             ip4->protocol = f->next_header;
+             ip4->protocol = next_header;
              ip4->length = len;
              next[0] = ESP_DECRYPT_NEXT_IP4_INPUT;
            }
        }
       else
        {
-         if (PREDICT_TRUE (f->next_header == IP_PROTOCOL_IP_IN_IP))
+         if (PREDICT_TRUE (next_header == IP_PROTOCOL_IP_IN_IP))
            {
              next[0] = ESP_DECRYPT_NEXT_IP4_INPUT;
              b[0]->current_data = pd->current_data + adv;
-             b[0]->current_length = pd->current_length - adv - tail;
+             b[0]->current_length = pd->current_length - adv;
+             esp_remove_tail (vm, b[0], pd->lb, tail);
            }
-         else if (f->next_header == IP_PROTOCOL_IPV6)
+         else if (next_header == IP_PROTOCOL_IPV6)
            {
              next[0] = ESP_DECRYPT_NEXT_IP6_INPUT;
              b[0]->current_data = pd->current_data + adv;
-             b[0]->current_length = pd->current_length - adv - tail;
+             b[0]->current_length = pd->current_length - adv;
+             esp_remove_tail (vm, b[0], pd->lb, tail);
            }
          else
            {
-             if (is_tun && f->next_header == IP_PROTOCOL_GRE)
+             if (is_tun && next_header == IP_PROTOCOL_GRE)
                {
                  gre_header_t *gre;
 
@@ -555,7 +850,7 @@ esp_decrypt_inline (vlib_main_t * vm,
                  itp = ipsec_tun_protect_get
                    (vnet_buffer (b[0])->ipsec.protect_index);
 
-                 if (PREDICT_TRUE (f->next_header == IP_PROTOCOL_IP_IN_IP))
+                 if (PREDICT_TRUE (next_header == IP_PROTOCOL_IP_IN_IP))
                    {
                      const ip4_header_t *ip4;
 
@@ -571,7 +866,7 @@ esp_decrypt_inline (vlib_main_t * vm,
                            node->errors[ESP_DECRYPT_ERROR_TUN_NO_PROTO];
                        }
                    }
-                 else if (f->next_header == IP_PROTOCOL_IPV6)
+                 else if (next_header == IP_PROTOCOL_IPV6)
                    {
                      const ip6_header_t *ip6;
 
@@ -618,7 +913,6 @@ esp_decrypt_inline (vlib_main_t * vm,
 
   vlib_buffer_enqueue_to_next (vm, node, from, nexts, n_left);
 
-  b = bufs;
   return n_left;
 }