cnat: Prepare extended snat policies

Type: refactor

Change-Id: I9ca3333274d6f32b6aff57f0fb3d2049c066337a
Signed-off-by: Nathan Skrzypczak <nathan.skrzypczak@gmail.com>

1 files changed, 542 insertions, 0 deletions

diff --git a/src/plugins/cnat/cnat_snat_policy.c b/src/plugins/cnat/cnat_snat_policy.c
new file mode 100644
index 00000000000..83a79c0544d
--- /dev/null
+++ b/src/plugins/cnat/cnat_snat_policy.c
@@ -0,0 +1,542 @@
+/*
+ * Copyright (c) 2020 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <vnet/ip/ip.h>
+#include <cnat/cnat_snat_policy.h>
+#include <cnat/cnat_translation.h>
+
+cnat_snat_policy_main_t cnat_snat_policy_main;
+
+uword
+unformat_cnat_snat_interface_map_type (unformat_input_t *input, va_list *args)
+{
+  u8 *a = va_arg (*args, u8 *);
+  if (unformat (input, "include-v4"))
+    *a = CNAT_SNAT_IF_MAP_INCLUDE_V4;
+  else if (unformat (input, "include-v6"))
+    *a = CNAT_SNAT_IF_MAP_INCLUDE_V6;
+  else
+    return 0;
+  return 1;
+}
+
+u8 *
+format_cnat_snat_interface_map_type (u8 *s, va_list *args)
+{
+  cnat_snat_interface_map_type_t mtype = va_arg (*args, int);
+  switch (mtype)
+    {
+    case CNAT_SNAT_IF_MAP_INCLUDE_V4:
+      s = format (s, "Included v4");
+      break;
+    case CNAT_SNAT_IF_MAP_INCLUDE_V6:
+      s = format (s, "Included v6");
+      break;
+    default:
+      s = format (s, "(unknown)");
+      break;
+    }
+  return (s);
+}
+
+u8 *
+format_cnat_snat_prefix (u8 *s, va_list *args)
+{
+  clib_bihash_kv_24_8_t *kv = va_arg (*args, clib_bihash_kv_24_8_t *);
+  CLIB_UNUSED (int verbose) = va_arg (*args, int);
+  u32 af = kv->key[2] >> 32;
+  u32 len = kv->key[2] & 0xffffffff;
+  if (AF_IP4 == af)
+    s = format (s, "%U/%d", format_ip4_address, &kv->key[0], len);
+  else
+    s = format (s, "%U/%d", format_ip6_address, &kv->key[0], len);
+  return (s);
+}
+
+static void
+cnat_compute_prefix_lengths_in_search_order (
+  cnat_snat_exclude_pfx_table_t *table, ip_address_family_t af)
+{
+  int i;
+  vec_reset_length (table->meta[af].prefix_lengths_in_search_order);
+  /* Note: bitmap reversed so this is in fact a longest prefix match */
+  clib_bitmap_foreach (i, table->meta[af].non_empty_dst_address_length_bitmap)
+    {
+      int dst_address_length = 128 - i;
+      vec_add1 (table->meta[af].prefix_lengths_in_search_order,
+		dst_address_length);
+    }
+}
+
+int
+cnat_snat_policy_add_del_if (u32 sw_if_index, u8 is_add,
+			     cnat_snat_interface_map_type_t table)
+{
+  cnat_snat_policy_main_t *cpm = &cnat_snat_policy_main;
+
+  if (table > ARRAY_LEN (cpm->interface_maps))
+    return VNET_API_ERROR_INVALID_VALUE;
+
+  clib_bitmap_t **map = &cpm->interface_maps[table];
+
+  *map = clib_bitmap_set (*map, sw_if_index, is_add);
+  return 0;
+}
+
+static clib_error_t *
+cnat_snat_policy_add_del_if_command_fn (vlib_main_t *vm,
+					unformat_input_t *input,
+					vlib_cli_command_t *cmd)
+{
+  vnet_main_t *vnm = vnet_get_main ();
+  int is_add = 1;
+  u32 sw_if_index = ~0;
+  u32 table;
+  int rv;
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "del"))
+	is_add = 0;
+      else if (unformat (input, "table %U",
+			 unformat_cnat_snat_interface_map_type, &table))
+	;
+      else if (unformat (input, "%U", unformat_vnet_sw_interface, vnm,
+			 &sw_if_index))
+	;
+      else
+	return clib_error_return (0, "unknown input '%U'",
+				  format_unformat_error, input);
+    }
+
+  if (sw_if_index == ~0)
+    return clib_error_return (0, "Interface not specified");
+
+  rv = cnat_snat_policy_add_del_if (sw_if_index, is_add, table);
+
+  if (rv)
+    return clib_error_return (0, "Error %d", rv);
+
+  return NULL;
+}
+
+VLIB_CLI_COMMAND (cnat_snat_policy_add_del_if_command, static) = {
+  .path = "set cnat snat-policy if",
+  .short_help = "set cnat snat-policy if [del]"
+		"[table [include-v4 include-v6]] [interface]",
+  .function = cnat_snat_policy_add_del_if_command_fn,
+};
+
+int
+cnat_snat_policy_add_pfx (ip_prefix_t *pfx)
+{
+  /* All packets destined to this prefix won't be source-NAT-ed */
+  cnat_snat_exclude_pfx_table_t *table = &cnat_snat_policy_main.excluded_pfx;
+  clib_bihash_kv_24_8_t kv;
+  ip6_address_t *mask;
+  u64 af = ip_prefix_version (pfx);
+  ;
+
+  mask = &table->ip_masks[pfx->len];
+  if (AF_IP4 == af)
+    {
+      kv.key[0] = (u64) ip_prefix_v4 (pfx).as_u32 & mask->as_u64[0];
+      kv.key[1] = 0;
+    }
+  else
+    {
+      kv.key[0] = ip_prefix_v6 (pfx).as_u64[0] & mask->as_u64[0];
+      kv.key[1] = ip_prefix_v6 (pfx).as_u64[1] & mask->as_u64[1];
+    }
+  kv.key[2] = ((u64) af << 32) | pfx->len;
+  clib_bihash_add_del_24_8 (&table->ip_hash, &kv, 1 /* is_add */);
+
+  table->meta[af].dst_address_length_refcounts[pfx->len]++;
+  table->meta[af].non_empty_dst_address_length_bitmap = clib_bitmap_set (
+    table->meta[af].non_empty_dst_address_length_bitmap, 128 - pfx->len, 1);
+  cnat_compute_prefix_lengths_in_search_order (table, af);
+  return 0;
+}
+
+int
+cnat_snat_policy_del_pfx (ip_prefix_t *pfx)
+{
+  cnat_snat_exclude_pfx_table_t *table = &cnat_snat_policy_main.excluded_pfx;
+  clib_bihash_kv_24_8_t kv, val;
+  ip6_address_t *mask;
+  u64 af = ip_prefix_version (pfx);
+  ;
+
+  mask = &table->ip_masks[pfx->len];
+  if (AF_IP4 == af)
+    {
+      kv.key[0] = (u64) ip_prefix_v4 (pfx).as_u32 & mask->as_u64[0];
+      kv.key[1] = 0;
+    }
+  else
+    {
+      kv.key[0] = ip_prefix_v6 (pfx).as_u64[0] & mask->as_u64[0];
+      kv.key[1] = ip_prefix_v6 (pfx).as_u64[1] & mask->as_u64[1];
+    }
+  kv.key[2] = ((u64) af << 32) | pfx->len;
+
+  if (clib_bihash_search_24_8 (&table->ip_hash, &kv, &val))
+    {
+      return 1;
+    }
+  clib_bihash_add_del_24_8 (&table->ip_hash, &kv, 0 /* is_add */);
+  /* refcount accounting */
+  ASSERT (table->meta[af].dst_address_length_refcounts[pfx->len] > 0);
+  if (--table->meta[af].dst_address_length_refcounts[pfx->len] == 0)
+    {
+      table->meta[af].non_empty_dst_address_length_bitmap =
+	clib_bitmap_set (table->meta[af].non_empty_dst_address_length_bitmap,
+			 128 - pfx->len, 0);
+      cnat_compute_prefix_lengths_in_search_order (table, af);
+    }
+  return 0;
+}
+
+int
+cnat_search_snat_prefix (ip46_address_t *addr, ip_address_family_t af)
+{
+  /* Returns 0 if addr matches any of the listed prefixes */
+  cnat_snat_exclude_pfx_table_t *table = &cnat_snat_policy_main.excluded_pfx;
+  clib_bihash_kv_24_8_t kv, val;
+  int i, n_p, rv;
+  n_p = vec_len (table->meta[af].prefix_lengths_in_search_order);
+  if (AF_IP4 == af)
+    {
+      kv.key[0] = addr->ip4.as_u32;
+      kv.key[1] = 0;
+    }
+  else
+    {
+      kv.key[0] = addr->as_u64[0];
+      kv.key[1] = addr->as_u64[1];
+    }
+
+  /*
+   * start search from a mask length same length or shorter.
+   * we don't want matches longer than the mask passed
+   */
+  i = 0;
+  for (; i < n_p; i++)
+    {
+      int dst_address_length =
+	table->meta[af].prefix_lengths_in_search_order[i];
+      ip6_address_t *mask = &table->ip_masks[dst_address_length];
+
+      ASSERT (dst_address_length >= 0 && dst_address_length <= 128);
+      /* As lengths are decreasing, masks are increasingly specific. */
+      kv.key[0] &= mask->as_u64[0];
+      kv.key[1] &= mask->as_u64[1];
+      kv.key[2] = ((u64) af << 32) | dst_address_length;
+      rv = clib_bihash_search_inline_2_24_8 (&table->ip_hash, &kv, &val);
+      if (rv == 0)
+	return 0;
+    }
+  return -1;
+}
+
+static_always_inline int
+cnat_snat_policy_interface_enabled (u32 sw_if_index, ip_address_family_t af)
+{
+  cnat_snat_policy_main_t *cpm = &cnat_snat_policy_main;
+  return clib_bitmap_get (cpm->interface_maps[af], sw_if_index);
+}
+
+int
+cnat_snat_policy_none (vlib_buffer_t *b, cnat_session_t *session)
+{
+  /* srcNAT everything by default */
+  return 1;
+}
+
+int
+cnat_snat_policy_if_pfx (vlib_buffer_t *b, cnat_session_t *session)
+{
+  ip46_address_t *dst_addr = &session->key.cs_ip[VLIB_TX];
+  u32 in_if = vnet_buffer (b)->sw_if_index[VLIB_RX];
+  ip_address_family_t af = session->key.cs_af;
+
+  /* source nat for outgoing connections */
+  if (cnat_snat_policy_interface_enabled (in_if, af))
+    if (cnat_search_snat_prefix (dst_addr, af))
+      /* Destination is not in the prefixes that don't require snat */
+      return 1;
+  return 0;
+}
+
+void
+cnat_set_snat (ip4_address_t *ip4, ip6_address_t *ip6, u32 sw_if_index)
+{
+  cnat_snat_policy_main_t *cpm = &cnat_snat_policy_main;
+
+  cnat_lazy_init ();
+
+  cnat_translation_unwatch_addr (INDEX_INVALID, CNAT_RESOLV_ADDR_SNAT);
+
+  ip_address_set (&cpm->snat_ip4.ce_ip, ip4, AF_IP4);
+  ip_address_set (&cpm->snat_ip6.ce_ip, ip6, AF_IP6);
+  cpm->snat_ip4.ce_sw_if_index = sw_if_index;
+  cpm->snat_ip6.ce_sw_if_index = sw_if_index;
+
+  cnat_resolve_ep (&cpm->snat_ip4);
+  cnat_resolve_ep (&cpm->snat_ip6);
+  cnat_translation_watch_addr (INDEX_INVALID, 0, &cpm->snat_ip4,
+			       CNAT_RESOLV_ADDR_SNAT);
+  cnat_translation_watch_addr (INDEX_INVALID, 0, &cpm->snat_ip6,
+			       CNAT_RESOLV_ADDR_SNAT);
+}
+
+static clib_error_t *
+cnat_set_snat_cli (vlib_main_t *vm, unformat_input_t *input,
+		   vlib_cli_command_t *cmd)
+{
+  unformat_input_t _line_input, *line_input = &_line_input;
+  vnet_main_t *vnm = vnet_get_main ();
+  ip4_address_t ip4 = { { 0 } };
+  ip6_address_t ip6 = { { 0 } };
+  clib_error_t *e = 0;
+  u32 sw_if_index = INDEX_INVALID;
+
+  cnat_lazy_init ();
+
+  /* Get a line of input. */
+  if (!unformat_user (input, unformat_line_input, line_input))
+    return 0;
+
+  while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat_user (line_input, unformat_ip4_address, &ip4))
+	;
+      else if (unformat_user (line_input, unformat_ip6_address, &ip6))
+	;
+      else if (unformat_user (line_input, unformat_vnet_sw_interface, vnm,
+			      &sw_if_index))
+	;
+      else
+	{
+	  e = clib_error_return (0, "unknown input '%U'",
+				 format_unformat_error, input);
+	  goto done;
+	}
+    }
+
+  cnat_set_snat (&ip4, &ip6, sw_if_index);
+
+done:
+  unformat_free (line_input);
+
+  return (e);
+}
+
+VLIB_CLI_COMMAND (cnat_set_snat_command, static) = {
+  .path = "set cnat snat-policy addr",
+  .short_help =
+    "set cnat snat-policy addr [<ip4-address>][<ip6-address>][sw_if_index]",
+  .function = cnat_set_snat_cli,
+};
+
+static clib_error_t *
+cnat_snat_policy_add_del_pfx_command_fn (vlib_main_t *vm,
+					 unformat_input_t *input,
+					 vlib_cli_command_t *cmd)
+{
+  ip_prefix_t pfx;
+  u8 is_add = 1;
+  int rv;
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "%U", unformat_ip_prefix, &pfx))
+	;
+      else if (unformat (input, "del"))
+	is_add = 0;
+      else
+	return (clib_error_return (0, "unknown input '%U'",
+				   format_unformat_error, input));
+    }
+
+  if (is_add)
+    rv = cnat_snat_policy_add_pfx (&pfx);
+  else
+    rv = cnat_snat_policy_del_pfx (&pfx);
+
+  if (rv)
+    return (clib_error_return (0, "error %d", rv, input));
+
+  return (NULL);
+}
+
+VLIB_CLI_COMMAND (cnat_snat_policy_add_del_pfx_command, static) = {
+  .path = "set cnat snat-policy prefix",
+  .short_help = "set cnat snat-policy prefix [del] [prefix]",
+  .function = cnat_snat_policy_add_del_pfx_command_fn,
+};
+
+static clib_error_t *
+cnat_show_snat (vlib_main_t *vm, unformat_input_t *input,
+		vlib_cli_command_t *cmd)
+{
+  cnat_snat_exclude_pfx_table_t *excluded_pfx =
+    &cnat_snat_policy_main.excluded_pfx;
+  cnat_snat_policy_main_t *cpm = &cnat_snat_policy_main;
+  vnet_main_t *vnm = vnet_get_main ();
+  u32 sw_if_index;
+
+  vlib_cli_output (vm, "Source NAT\n  ip4: %U\n  ip6: %U\n\n",
+		   format_cnat_endpoint, &cpm->snat_ip4, format_cnat_endpoint,
+		   &cpm->snat_ip6);
+  vlib_cli_output (vm, "Excluded prefixes:\n  %U\n", format_bihash_24_8,
+		   &excluded_pfx->ip_hash, 1);
+
+  for (int i = 0; i < CNAT_N_SNAT_IF_MAP; i++)
+    {
+      vlib_cli_output (vm, "\n%U interfaces:\n",
+		       format_cnat_snat_interface_map_type, i);
+      clib_bitmap_foreach (sw_if_index, cpm->interface_maps[i])
+	vlib_cli_output (vm, "  %U\n", format_vnet_sw_if_index_name, vnm,
+			 sw_if_index);
+    }
+
+  return (NULL);
+}
+
+VLIB_CLI_COMMAND (cnat_show_snat_command, static) = {
+  .path = "show cnat snat-policy",
+  .short_help = "show cnat snat-policy",
+  .function = cnat_show_snat,
+};
+
+int
+cnat_set_snat_policy (cnat_snat_policy_type_t policy)
+{
+  cnat_snat_policy_main_t *cpm = &cnat_snat_policy_main;
+  switch (policy)
+    {
+    case CNAT_SNAT_POLICY_NONE:
+      cpm->snat_policy = cnat_snat_policy_none;
+      break;
+    case CNAT_SNAT_POLICY_IF_PFX:
+      cpm->snat_policy = cnat_snat_policy_if_pfx;
+      break;
+    default:
+      return 1;
+    }
+  return 0;
+}
+
+static clib_error_t *
+cnat_snat_policy_set_cmd_fn (vlib_main_t *vm, unformat_input_t *input,
+			     vlib_cli_command_t *cmd)
+{
+  cnat_snat_policy_type_t policy = CNAT_SNAT_POLICY_NONE;
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "none"))
+	;
+      else if (unformat (input, "if-pfx"))
+	policy = CNAT_SNAT_POLICY_IF_PFX;
+      else
+	return clib_error_return (0, "unknown input '%U'",
+				  format_unformat_error, input);
+    }
+
+  cnat_set_snat_policy (policy);
+  return NULL;
+}
+
+VLIB_CLI_COMMAND (cnat_snat_policy_set_cmd, static) = {
+  .path = "set cnat snat-policy",
+  .short_help = "set cnat snat-policy [none][if-pfx]",
+  .function = cnat_snat_policy_set_cmd_fn,
+};
+
+static void
+cnat_if_addr_add_del_snat_cb (addr_resolution_t *ar, ip_address_t *address,
+			      u8 is_del)
+{
+  cnat_snat_policy_main_t *cpm = &cnat_snat_policy_main;
+  cnat_endpoint_t *ep;
+
+  ep = AF_IP4 == ar->af ? &cpm->snat_ip4 : &cpm->snat_ip6;
+
+  if (!is_del && ep->ce_flags & CNAT_EP_FLAG_RESOLVED)
+    return;
+
+  if (is_del)
+    {
+      ep->ce_flags &= ~CNAT_EP_FLAG_RESOLVED;
+      /* Are there remaining addresses ? */
+      if (0 == cnat_resolve_addr (ar->sw_if_index, ar->af, address))
+	is_del = 0;
+    }
+
+  if (!is_del)
+    {
+      ip_address_copy (&ep->ce_ip, address);
+      ep->ce_flags |= CNAT_EP_FLAG_RESOLVED;
+    }
+}
+
+static clib_error_t *
+cnat_snat_init (vlib_main_t *vm)
+{
+  cnat_snat_policy_main_t *cpm = &cnat_snat_policy_main;
+  cnat_main_t *cm = &cnat_main;
+  cnat_snat_exclude_pfx_table_t *excluded_pfx = &cpm->excluded_pfx;
+
+  int i;
+  for (i = 0; i < ARRAY_LEN (excluded_pfx->ip_masks); i++)
+    {
+      u32 j, i0, i1;
+
+      i0 = i / 32;
+      i1 = i % 32;
+
+      for (j = 0; j < i0; j++)
+	excluded_pfx->ip_masks[i].as_u32[j] = ~0;
+
+      if (i1)
+	excluded_pfx->ip_masks[i].as_u32[i0] =
+	  clib_host_to_net_u32 (pow2_mask (i1) << (32 - i1));
+    }
+  clib_bihash_init_24_8 (&excluded_pfx->ip_hash, "snat prefixes",
+			 cm->snat_hash_buckets, cm->snat_hash_memory);
+  clib_bihash_set_kvp_format_fn_24_8 (&excluded_pfx->ip_hash,
+				      format_cnat_snat_prefix);
+
+  for (int i = 0; i < CNAT_N_SNAT_IF_MAP; i++)
+    clib_bitmap_validate (cpm->interface_maps[i], cm->snat_if_map_length);
+
+  cnat_translation_register_addr_add_cb (CNAT_RESOLV_ADDR_SNAT,
+					 cnat_if_addr_add_del_snat_cb);
+
+  cpm->snat_policy = cnat_snat_policy_none;
+
+  return (NULL);
+}
+
+VLIB_INIT_FUNCTION (cnat_snat_init);
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */