mss_clamp: TCP MSS clamping plugin

Type: feature

Configure TCP MSS clamping on an interface as follows:
set interface tcp-mss-clamp [rx|tx] <interface-name>
  ip4 [enable|disable|rx|tx] ip4-mss <size>
  ip6 [enable|disable|rx|tx] ip6-mss <size>

Change-Id: I45b04e50a0b70a33e14a9066f981c651292ebffb
Signed-off-by: Neale Ranns <neale.ranns@cisco.com>
Signed-off-by: Paul Vinciguerra <pvinci@vinciconsulting.com>
Signed-off-by: Miklos Tirpak <miklos.tirpak@gmail.com>
Signed-off-by: Matthew Smith <mgsmith@netgate.com>

1 files changed, 292 insertions, 0 deletions

diff --git a/src/plugins/mss_clamp/mss_clamp.c b/src/plugins/mss_clamp/mss_clamp.c
new file mode 100644
index 00000000000..cdac5456641
--- /dev/null
+++ b/src/plugins/mss_clamp/mss_clamp.c
@@ -0,0 +1,292 @@
+/*
+ * mss_clamp.c - TCP MSS clamping plug-in
+ *
+ * Copyright (c) 2018 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/vnet.h>
+#include <vnet/plugin/plugin.h>
+#include <mss_clamp/mss_clamp.h>
+#include <mss_clamp/mss_clamp.api_types.h>
+
+mssc_main_t mssc_main;
+
+/* Action function shared between message handler and debug CLI */
+
+static void
+mssc_enable_disable_feat (u32 sw_if_index, u8 dir4, u8 dir6, int enable)
+{
+  if (dir4 == MSS_CLAMP_DIR_NONE && dir6 == MSS_CLAMP_DIR_NONE)
+    return;
+
+  // ip4
+  if ((dir4 & MSS_CLAMP_DIR_RX) != MSS_CLAMP_DIR_NONE)
+    vnet_feature_enable_disable ("ip4-unicast", "tcp-mss-clamping-ip4-in",
+				 sw_if_index, enable, 0, 0);
+  if ((dir4 & MSS_CLAMP_DIR_TX) != MSS_CLAMP_DIR_NONE)
+    vnet_feature_enable_disable ("ip4-output", "tcp-mss-clamping-ip4-out",
+				 sw_if_index, enable, 0, 0);
+  // ip6
+  if ((dir6 & MSS_CLAMP_DIR_RX) != MSS_CLAMP_DIR_NONE)
+    vnet_feature_enable_disable ("ip6-unicast", "tcp-mss-clamping-ip6-in",
+				 sw_if_index, enable, 0, 0);
+  if ((dir6 & MSS_CLAMP_DIR_TX) != MSS_CLAMP_DIR_NONE)
+    vnet_feature_enable_disable ("ip6-output", "tcp-mss-clamping-ip6-out",
+				 sw_if_index, enable, 0, 0);
+}
+
+int
+mssc_enable_disable (u32 sw_if_index, u8 dir4, u8 dir6, u16 mss4, u16 mss6)
+{
+  mssc_main_t *cm = &mssc_main;
+  u8 *dir_enabled4, *dir_enabled6;
+  int rv = 0;
+
+  if (dir4 == MSS_CLAMP_DIR_NONE)
+    mss4 = MSS_CLAMP_UNSET;
+  if (dir6 == MSS_CLAMP_DIR_NONE)
+    mss6 = MSS_CLAMP_UNSET;
+
+  vec_validate_init_empty (cm->dir_enabled4, sw_if_index, MSS_CLAMP_DIR_NONE);
+  vec_validate_init_empty (cm->dir_enabled6, sw_if_index, MSS_CLAMP_DIR_NONE);
+  vec_validate_init_empty (cm->max_mss4, sw_if_index, MSS_CLAMP_UNSET);
+  vec_validate_init_empty (cm->max_mss6, sw_if_index, MSS_CLAMP_UNSET);
+
+  cm->max_mss4[sw_if_index] = mss4;
+  cm->max_mss6[sw_if_index] = mss6;
+  dir_enabled4 = &cm->dir_enabled4[sw_if_index];
+  dir_enabled6 = &cm->dir_enabled6[sw_if_index];
+
+  // Disable the directions that are no longer needed
+  mssc_enable_disable_feat (sw_if_index, (*dir_enabled4) & ~dir4,
+			    (*dir_enabled6) & ~dir6, 0);
+  // Enable the new directions
+  mssc_enable_disable_feat (sw_if_index, ~(*dir_enabled4) & dir4,
+			    ~(*dir_enabled6) & dir6, 1);
+
+  *dir_enabled4 = dir4;
+  *dir_enabled6 = dir6;
+
+  return rv;
+}
+
+int
+mssc_get_mss (u32 sw_if_index, u8 *dir4, u8 *dir6, u16 *mss4, u16 *mss6)
+{
+  mssc_main_t *cm = &mssc_main;
+  int rv = VNET_API_ERROR_FEATURE_DISABLED;
+
+  if (vec_len (cm->dir_enabled4) > sw_if_index &&
+      MSS_CLAMP_DIR_NONE != cm->dir_enabled4[sw_if_index])
+    {
+      *mss4 = cm->max_mss4[sw_if_index];
+      *dir4 = cm->dir_enabled4[sw_if_index];
+      rv = 0;
+    }
+  else
+    {
+      *mss4 = MSS_CLAMP_DIR_NONE;
+      *dir4 = 0;
+    }
+
+  if (vec_len (cm->dir_enabled6) > sw_if_index &&
+      MSS_CLAMP_DIR_NONE != cm->dir_enabled6[sw_if_index])
+    {
+      *mss6 = cm->max_mss6[sw_if_index];
+      *dir6 = cm->dir_enabled6[sw_if_index];
+      rv = 0;
+    }
+  else
+    {
+      *mss6 = MSS_CLAMP_DIR_NONE;
+      *dir6 = 0;
+    }
+  return rv;
+}
+
+static uword
+unformat_mssc_dir (unformat_input_t *input, va_list *args)
+{
+  u8 *result = va_arg (*args, u8 *);
+  u8 dir = MSS_CLAMP_DIR_RX | MSS_CLAMP_DIR_TX;
+
+  if (unformat (input, "disable"))
+    dir = MSS_CLAMP_DIR_NONE;
+  else if (unformat (input, "enable"))
+    dir = MSS_CLAMP_DIR_RX | MSS_CLAMP_DIR_TX;
+  else if (unformat (input, "rx"))
+    dir = MSS_CLAMP_DIR_RX;
+  else if (unformat (input, "tx"))
+    dir = MSS_CLAMP_DIR_TX;
+  else
+    return 0;
+
+  *result = dir;
+  return 1;
+}
+
+static clib_error_t *
+mssc_enable_command_fn (vlib_main_t *vm, unformat_input_t *input,
+			vlib_cli_command_t *cmd)
+{
+  u32 sw_if_index = ~0;
+  u8 dir4 = ~0, dir6 = ~0;
+  u32 mss4 = ~0, mss6 = ~0;
+  int rv;
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "ip4 %U", unformat_mssc_dir, &dir4))
+	;
+      else if (unformat (input, "ip6 %U", unformat_mssc_dir, &dir6))
+	;
+      else if (unformat (input, "ip4-mss %d", &mss4))
+	;
+      else if (unformat (input, "ip6-mss %d", &mss6))
+	;
+      else if (unformat (input, "%U", unformat_vnet_sw_interface,
+			 vnet_get_main (), &sw_if_index))
+	;
+      else
+	break;
+    }
+
+  if (sw_if_index == ~0)
+    return clib_error_return (0, "Please specify an interface");
+
+  if (dir4 == (u8) ~0 || dir6 == (u8) ~0)
+    return clib_error_return (
+      0, "Please specify the MSS clamping direction for ip4 and ip6");
+
+  if (dir4 != MSS_CLAMP_DIR_NONE)
+    {
+      if (mss4 == ~0)
+	return clib_error_return (
+	  0, "Please specify the Max Segment Size for ip4");
+      if (mss4 >= MSS_CLAMP_UNSET)
+	return clib_error_return (0, "Invalid Max Segment Size");
+    }
+  if (dir6 != MSS_CLAMP_DIR_NONE)
+    {
+      if (mss6 == ~0)
+	return clib_error_return (
+	  0, "Please specify the Max Segment Size for ip6");
+      if (mss6 >= MSS_CLAMP_UNSET)
+	return clib_error_return (0, "Invalid Max Segment Size");
+    }
+
+  rv = mssc_enable_disable (sw_if_index, dir4, dir6, mss4, mss6);
+
+  if (rv)
+    return clib_error_return (0, "Failed: %d = %U", rv, format_vnet_api_errno,
+			      rv);
+
+  return (NULL);
+}
+
+VLIB_CLI_COMMAND (mssc_enable_disable_command, static) = {
+  .path = "set interface tcp-mss-clamp",
+  .short_help = "set interface tcp-mss-clamp <interface-name> "
+		"ip4 [enable|disable|rx|tx] ip4-mss <size> "
+		"ip6 [enable|disable|rx|tx] ip6-mss <size>",
+  .function = mssc_enable_command_fn,
+};
+
+static u8 *
+format_mssc_clamping (u8 *s, va_list *args)
+{
+  u8 dir = va_arg (*args, u32);
+  u16 mss = va_arg (*args, u32);
+#define DIR2S(d)                                                              \
+  (((d) == (MSS_CLAMP_DIR_RX | MSS_CLAMP_DIR_TX)) ?                           \
+     "" :                                                                     \
+     (((d) == MSS_CLAMP_DIR_RX) ? " [RX]" : " [TX]"))
+
+  if (MSS_CLAMP_DIR_NONE == dir)
+    {
+      return format (s, "disabled");
+    }
+  u32 mss_u32 = mss;
+  return format (s, "%d%s", mss_u32, DIR2S (dir));
+}
+
+static clib_error_t *
+mssc_show_command_fn (vlib_main_t *vm, unformat_input_t *input,
+		      vlib_cli_command_t *cmd)
+{
+  mssc_main_t *cm = &mssc_main;
+  u32 sw_if_index = ~0;
+  u32 ii;
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "%U", unformat_vnet_sw_interface, vnet_get_main (),
+		    &sw_if_index))
+	;
+      else
+	break;
+    }
+
+  if (sw_if_index == ~0)
+    {
+      vec_foreach_index (ii, cm->dir_enabled4)
+	{
+	  u8 dir4 = cm->dir_enabled4[ii];
+	  u8 dir6 = cm->dir_enabled6[ii];
+	  if (MSS_CLAMP_DIR_NONE != dir4 || MSS_CLAMP_DIR_NONE != dir6)
+	    {
+	      u16 mss4 = cm->max_mss4[ii];
+	      u16 mss6 = cm->max_mss6[ii];
+	      vlib_cli_output (vm, "%U: ip4: %U ip6: %U",
+			       format_vnet_sw_if_index_name, vnet_get_main (),
+			       ii, format_mssc_clamping, dir4, mss4,
+			       format_mssc_clamping, dir6, mss6);
+	    }
+	}
+    }
+  else
+    {
+      u16 mss4, mss6;
+      u8 dir4, dir6;
+      mssc_get_mss (sw_if_index, &dir4, &dir6, &mss4, &mss6);
+      vlib_cli_output (vm, "%U: ip4: %U ip6: %U", format_vnet_sw_if_index_name,
+		       vnet_get_main (), sw_if_index, format_mssc_clamping,
+		       dir4, mss4, format_mssc_clamping, dir6, mss6);
+    }
+
+  return (NULL);
+}
+
+VLIB_CLI_COMMAND (mssc_show_command, static) = {
+  .path = "show interface tcp-mss-clamp",
+  .short_help = "show interface tcp-mss-clamp [interface-name]",
+  .long_help = "show TCP MSS clamping configurations",
+  .function = mssc_show_command_fn,
+};
+
+static clib_error_t *
+mssc_init (vlib_main_t *vm)
+{
+  return NULL;
+}
+
+VLIB_INIT_FUNCTION (mssc_init);
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */