sr_mpls_steering.c

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/*
 * sr_steering.c: ipv6 segment routing steering into SR policy
 *
 * Copyright (c) 2016 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.
 */

/**
 * @file
 * @brief Packet steering into SR-MPLS Policies
 *
 * This file is in charge of handling the FIB appropiatly to steer packets
 * through SR Policies as defined in 'sr_mpls_policy.c'. Notice that here
 * we are only doing steering. SR policy application is done in
 * sr_policy_rewrite.c
 *
 * Supports:
 *  - Steering of IPv6 traffic Destination Address based
 *  - Steering of IPv4 traffic Destination Address based
 */

#include <vlib/vlib.h>
#include <vnet/vnet.h>
#include <vnet/srmpls/sr.h>
#include <vnet/ip/ip4_packet.h>
#include <vnet/ip/ip6_packet.h>
#include <vnet/fib/mpls_fib.h>

#include <vppinfra/error.h>
#include <vppinfra/elog.h>

/**
 * @brief Steer traffic L3 traffic through a given SR-MPLS policy
 *
 * @param is_del
 * @param bsid is the bindingSID of the SR Policy (alt to sr_policy_index)
 * @param sr_policy is the index of the SR Policy (alt to bsid)
 * @param table_id is the VRF where to install the FIB entry for the BSID
 * @param prefix is the IPv4/v6 address for L3 traffic type
 * @param mask_width is the mask for L3 traffic type
 * @param traffic_type describes the type of traffic
 *
 * @return 0 if correct, else error
 */
int
sr_mpls_steering_policy (int is_del, mpls_label_t bsid, u32 sr_policy_index,
                         u32 table_id, ip46_address_t * prefix,
                         u32 mask_width, u8 traffic_type)
{
  mpls_sr_main_t *sm = &sr_mpls_main;
  sr_mpls_steering_key_t key;
  mpls_sr_steering_policy_t *steer_pl;
  fib_prefix_t pfx = { 0 };

  mpls_sr_policy_t *sr_policy = 0;
  uword *p = 0;

  memset (&key, 0, sizeof (sr_mpls_steering_key_t));

  /* Compute the steer policy key */
  if (traffic_type == SR_STEER_IPV4 || traffic_type == SR_STEER_IPV6)
    {
      key.prefix.as_u64[0] = prefix->as_u64[0];
      key.prefix.as_u64[1] = prefix->as_u64[1];
      key.mask_width = mask_width;
      key.fib_table = (table_id != (u32) ~ 0 ? table_id : 0);
    }
  else
    return -1;

  key.traffic_type = traffic_type;

  /* Search for the item */
  p = mhash_get (&sm->sr_steer_policies_hash, &key);

  if (p)
    {
      /* Retrieve Steer Policy function */
      steer_pl = pool_elt_at_index (sm->steer_policies, p[0]);

      if (is_del)
        {
          if (steer_pl->classify.traffic_type == SR_STEER_IPV6)
            {
              /* Remove FIB entry */
              pfx.fp_proto = FIB_PROTOCOL_IP6;
              pfx.fp_len = steer_pl->classify.mask_width;
              pfx.fp_addr.ip6 = steer_pl->classify.prefix.ip6;

              fib_table_entry_delete (fib_table_find
                                      (FIB_PROTOCOL_MPLS,
                                       steer_pl->classify.fib_table), &pfx,
                                      FIB_SOURCE_SR);
            }
          else if (steer_pl->classify.traffic_type == SR_STEER_IPV4)
            {
              /* Remove FIB entry */
              pfx.fp_proto = FIB_PROTOCOL_IP4;
              pfx.fp_len = steer_pl->classify.mask_width;
              pfx.fp_addr.ip4 = steer_pl->classify.prefix.ip4;

              fib_table_entry_delete (fib_table_find
                                      (FIB_PROTOCOL_MPLS,
                                       steer_pl->classify.fib_table), &pfx,
                                      FIB_SOURCE_SR);
            }

          /* Delete SR steering policy entry */
          pool_put (sm->steer_policies, steer_pl);
          mhash_unset (&sm->sr_steer_policies_hash, &key, NULL);

          return 1;
        }
      else                      /* It means user requested to update an existing SR steering policy */
        {
          /* Retrieve SR steering policy */
          if (bsid)             //TODO FIXME
            {
              p = hash_get (sm->sr_policies_index_hash, bsid);
              if (p)
                sr_policy = pool_elt_at_index (sm->sr_policies, p[0]);
              else
                return -2;
            }
          else
            sr_policy = pool_elt_at_index (sm->sr_policies, sr_policy_index);

          if (!sr_policy)
            return -2;

          steer_pl->sr_policy = sr_policy - sm->sr_policies;

          /* Remove old FIB/hw redirection and create a new one */
          if (steer_pl->classify.traffic_type == SR_STEER_IPV6)
            {
              /* Remove FIB entry */
              pfx.fp_proto = FIB_PROTOCOL_IP6;
              pfx.fp_len = steer_pl->classify.mask_width;
              pfx.fp_addr.ip6 = steer_pl->classify.prefix.ip6;

              fib_table_entry_delete (fib_table_find
                                      (FIB_PROTOCOL_IP6,
                                       steer_pl->classify.fib_table), &pfx,
                                      FIB_SOURCE_SR);

              /* Create a new one */
              goto update_fib;
            }
          else if (steer_pl->classify.traffic_type == SR_STEER_IPV4)
            {
              /* Remove FIB entry */
              pfx.fp_proto = FIB_PROTOCOL_IP4;
              pfx.fp_len = steer_pl->classify.mask_width;
              pfx.fp_addr.ip4 = steer_pl->classify.prefix.ip4;

              fib_table_entry_delete (fib_table_find
                                      (FIB_PROTOCOL_IP4,
                                       steer_pl->classify.fib_table), &pfx,
                                      FIB_SOURCE_SR);

              /* Create a new one */
              goto update_fib;
            }
        }
    }
  else
    /* delete; steering policy does not exist; complain */
  if (is_del)
    return -4;

  /* Retrieve SR policy */
  if (bsid)                     //FIX
    {
      p = hash_get (sm->sr_policies_index_hash, bsid);
      if (p)
        sr_policy = pool_elt_at_index (sm->sr_policies, p[0]);
      else
        return -2;
    }
  else
    sr_policy = pool_elt_at_index (sm->sr_policies, sr_policy_index);

  /* Create a new steering policy */
  pool_get (sm->steer_policies, steer_pl);
  memset (steer_pl, 0, sizeof (*steer_pl));

  if (traffic_type == SR_STEER_IPV4 || traffic_type == SR_STEER_IPV6)
    {
      clib_memcpy (&steer_pl->classify.prefix, prefix,
                   sizeof (ip46_address_t));
      steer_pl->classify.mask_width = mask_width;
      steer_pl->classify.fib_table = (table_id != (u32) ~ 0 ? table_id : 0);
      steer_pl->classify.traffic_type = traffic_type;
    }
  else
    {
      /* Incorrect API usage. Should never get here */
      pool_put (sm->steer_policies, steer_pl);
      mhash_unset (&sm->sr_steer_policies_hash, &key, NULL);
      return -1;
    }
  steer_pl->sr_policy = sr_policy - sm->sr_policies;

  /* Create and store key */
  mhash_set (&sm->sr_steer_policies_hash, &key, steer_pl - sm->steer_policies,
             NULL);

update_fib:;

  fib_route_path_t path = {
    .frp_proto = FIB_PROTOCOL_MPLS,
    .frp_local_label = sr_policy->bsid,
    .frp_eos = MPLS_EOS,
    .frp_sw_if_index = ~0,
    .frp_fib_index = 0,
    .frp_weight = 1,
    .frp_flags = FIB_ROUTE_PATH_FLAG_NONE,
    .frp_label_stack = NULL
  };

  fib_route_path_t *paths = NULL;

  /* FIB API calls - Recursive route through the BindingSID */
  if (traffic_type == SR_STEER_IPV6)
    {
      pfx.fp_proto = FIB_PROTOCOL_IP6;
      pfx.fp_len = steer_pl->classify.mask_width;
      pfx.fp_addr.ip6 = steer_pl->classify.prefix.ip6;
      path.frp_fib_index = 0;

      vec_add1 (paths, path);

      fib_table_entry_path_add2 (fib_table_find
                                 (FIB_PROTOCOL_IP6,
                                  (table_id != (u32) ~ 0 ? table_id : 0)),
                                 &pfx, FIB_SOURCE_SR,
                                 FIB_ENTRY_FLAG_LOOSE_URPF_EXEMPT, paths);

      vec_free (paths);
    }
  else if (traffic_type == SR_STEER_IPV4)
    {
      pfx.fp_proto = FIB_PROTOCOL_IP4;
      pfx.fp_len = steer_pl->classify.mask_width;
      pfx.fp_addr.ip4 = steer_pl->classify.prefix.ip4;
      path.frp_fib_index = 0;

      vec_add1 (paths, path);

      fib_table_entry_path_add2 (fib_table_find
                                 (FIB_PROTOCOL_IP4,
                                  (table_id != (u32) ~ 0 ? table_id : 0)),
                                 &pfx, FIB_SOURCE_SR,
                                 FIB_ENTRY_FLAG_LOOSE_URPF_EXEMPT, paths);

      vec_free (paths);
    }

  return 0;
}

static clib_error_t *
sr_mpls_steer_policy_command_fn (vlib_main_t * vm, unformat_input_t * input,
                                 vlib_cli_command_t * cmd)
{
  int is_del = 0;

  ip46_address_t prefix;
  u32 dst_mask_width = 0;
  u8 traffic_type = 0;
  u32 fib_table = (u32) ~ 0;

  mpls_label_t bsid;
  u32 sr_policy_index = (u32) ~ 0;

  u8 sr_policy_set = 0;

  memset (&prefix, 0, sizeof (ip46_address_t));

  int rv;
  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
    {
      if (unformat (input, "del"))
        is_del = 1;
      else if (!traffic_type
               && unformat (input, "l3 %U/%d", unformat_ip6_address,
                            &prefix.ip6, &dst_mask_width))
        traffic_type = SR_STEER_IPV6;
      else if (!traffic_type
               && unformat (input, "l3 %U/%d", unformat_ip4_address,
                            &prefix.ip4, &dst_mask_width))
        traffic_type = SR_STEER_IPV4;
      else if (!sr_policy_set
               && unformat (input, "via sr policy index %d",
                            &sr_policy_index))
        sr_policy_set = 1;
      else if (!sr_policy_set
               && unformat (input, "via sr policy bsid %U",
                            unformat_mpls_unicast_label, &bsid))
        sr_policy_set = 1;
      else if (fib_table == (u32) ~ 0
               && unformat (input, "fib-table %d", &fib_table));
      else
        break;
    }

  if (!traffic_type)
    return clib_error_return (0, "No L3 traffic specified");
  if (!sr_policy_set)
    return clib_error_return (0, "No SR policy specified");

  /* Make sure that the prefixes are clean */
  if (traffic_type == SR_STEER_IPV4)
    {
      u32 mask =
        (dst_mask_width ? (0xFFFFFFFFu >> (32 - dst_mask_width)) : 0);
      prefix.ip4.as_u32 &= mask;
    }
  else if (traffic_type == SR_STEER_IPV6)
    {
      ip6_address_t mask;
      ip6_address_mask_from_width (&mask, dst_mask_width);
      ip6_address_mask (&prefix.ip6, &mask);
    }

  rv =
    sr_mpls_steering_policy (is_del, bsid,
                             sr_policy_index, fib_table, &prefix,
                             dst_mask_width, traffic_type);

  switch (rv)
    {
    case 0:
      break;
    case 1:
      return 0;
    case -1:
      return clib_error_return (0, "Incorrect API usage.");
    case -2:
      return clib_error_return (0,
                                "The requested SR policy could not be located. Review the BSID/index.");
    case -3:
      return clib_error_return (0,
                                "Unable to do SW redirect. Incorrect interface.");
    case -4:
      return clib_error_return (0,
                                "The requested SR steering policy could not be deleted.");
    case -5:
      return clib_error_return (0,
                                "The SR policy is not an encapsulation one.");
    default:
      return clib_error_return (0, "BUG: sr steer policy returns %d", rv);
    }
  return 0;
}

/* *INDENT-OFF* */
VLIB_CLI_COMMAND (sr_mpls_steer_policy_command, static) = {
  .path = "sr mpls steer",
  .short_help = "sr mpls steer (del) l3 <ip_addr/mask>"
    "via sr policy bsid <mpls_label> (fib-table <fib_table_index>)",
  .long_help =
    "\tSteer L3 traffic through an existing SR policy.\n"
    "\tExamples:\n"
    "\t\tsr steer l3 2001::/64 via sr_policy index 5\n"
    "\t\tsr steer l3 2001::/64 via sr_policy bsid 29999\n"
    "\t\tsr steer del l3 2001::/64 via sr_policy index 5\n",
  .function = sr_mpls_steer_policy_command_fn,
};
/* *INDENT-ON* */

static clib_error_t *
show_sr_mpls_steering_policies_command_fn (vlib_main_t * vm,
                                           unformat_input_t * input,
                                           vlib_cli_command_t * cmd)
{
  mpls_sr_main_t *sm = &sr_mpls_main;
  mpls_sr_steering_policy_t **steer_policies = 0;
  mpls_sr_steering_policy_t *steer_pl;

  mpls_sr_policy_t *pl = 0;
  int i;

  vlib_cli_output (vm, "SR MPLS steering policies:");
  /* *INDENT-OFF* */
  pool_foreach (steer_pl, sm->steer_policies, ({vec_add1(steer_policies, steer_pl);}));
  /* *INDENT-ON* */
  vlib_cli_output (vm, "Traffic\t\tSR policy BSID");
  for (i = 0; i < vec_len (steer_policies); i++)
    {
      steer_pl = steer_policies[i];
      pl = pool_elt_at_index (sm->sr_policies, steer_pl->sr_policy);
      if (steer_pl->classify.traffic_type == SR_STEER_IPV4)
        {
          vlib_cli_output (vm, "L3 %U/%d\t%U",
                           format_ip4_address,
                           &steer_pl->classify.prefix.ip4,
                           steer_pl->classify.mask_width,
                           format_mpls_unicast_label, pl->bsid);
        }
      else if (steer_pl->classify.traffic_type == SR_STEER_IPV6)
        {
          vlib_cli_output (vm, "L3 %U/%d\t%U",
                           format_ip6_address,
                           &steer_pl->classify.prefix.ip6,
                           steer_pl->classify.mask_width,
                           format_mpls_unicast_label, pl->bsid);
        }
    }
  return 0;
}

/* *INDENT-OFF* */
VLIB_CLI_COMMAND (show_sr_mpls_steering_policies_command, static) = {
  .path = "show sr mpls steering policies",
  .short_help = "show sr mpls steering policies",
  .function = show_sr_mpls_steering_policies_command_fn,
};
/* *INDENT-ON* */

clib_error_t *
sr_mpls_steering_init (vlib_main_t * vm)
{
  mpls_sr_main_t *sm = &sr_mpls_main;

  /* Init memory for function keys */
  mhash_init (&sm->sr_steer_policies_hash, sizeof (uword),
              sizeof (sr_mpls_steering_key_t));

  return 0;
}

/* *INDENT-OFF* */
VLIB_INIT_FUNCTION (sr_mpls_steering_init);
/* *INDENT-ON* */

/*
* fd.io coding-style-patch-verification: ON
*
* Local Variables:
* eval: (c-set-style "gnu")
* End:
*/