/*-
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2020 Alexander V. Chernikov
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#include "opt_inet.h"
#include "opt_route.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/lock.h>
#include <sys/rwlock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/kernel.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/route.h>
#include <net/route/route_var.h>
#include <net/route/nhop_utils.h>
#include <net/route/nhop.h>
#include <net/route/nhop_var.h>
#include <net/vnet.h>
#define DEBUG_MOD_NAME nhop
#define DEBUG_MAX_LEVEL LOG_DEBUG
#include <net/route/route_debug.h>
_DECLARE_DEBUG(LOG_INFO);
/*
* This file contains data structures management logic for the nexthop ("nhop")
* route subsystem.
*
* Nexthops in the original sense are the objects containing all the necessary
* information to forward the packet to the selected destination.
* In particular, nexthop is defined by a combination of
* ifp, ifa, aifp, mtu, gw addr(if set), nh_type, nh_family, mask of rt_flags and
* NHF_DEFAULT
*
* All nexthops are stored in the resizable hash table.
* Additionally, each nexthop gets assigned its unique index (nexthop index)
* so userland programs can interact with the nexthops easier. Index allocation
* is backed by the bitmask array.
*/
MALLOC_DEFINE(M_NHOP, "nhops", "nexthops data");
/* Hash management functions */
int
nhops_init_rib(struct rib_head *rh)
{
struct nh_control *ctl;
size_t alloc_size;
uint32_t num_buckets, num_items;
void *ptr;
ctl = malloc(sizeof(struct nh_control), M_NHOP, M_WAITOK | M_ZERO);
/*
* Allocate nexthop hash. Start with 16 items by default (128 bytes).
* This will be enough for most of the cases.
*/
num_buckets = 16;
alloc_size = CHT_SLIST_GET_RESIZE_SIZE(num_buckets);
ptr = malloc(alloc_size, M_NHOP, M_WAITOK | M_ZERO);
CHT_SLIST_INIT(&ctl->nh_head, ptr, num_buckets);
/*
* Allocate nexthop index bitmask.
*/
num_items = 128 * 8; /* 128 bytes */
ptr = malloc(bitmask_get_size(num_items), M_NHOP, M_WAITOK | M_ZERO);
bitmask_init(&ctl->nh_idx_head, ptr, num_items);
NHOPS_LOCK_INIT(ctl);
rh->nh_control = ctl;
ctl->ctl_rh = rh;
FIB_CTL_LOG(LOG_DEBUG2, ctl, "nhops init: ctl %p rh %p", ctl, rh);
return (0);
}
static void
destroy_ctl(struct nh_control *ctl)
{
NHOPS_LOCK_DESTROY(ctl);
free(ctl->nh_head.ptr, M_NHOP);
free(ctl->nh_idx_head.idx, M_NHOP);
#ifdef ROUTE_MPATH
nhgrp_ctl_free(ctl);
#endif
free(ctl, M_NHOP);
}
/*
* Epoch callback indicating ctl is safe to destroy
*/
static void
destroy_ctl_epoch(epoch_context_t ctx)
{
struct nh_control *ctl;
ctl = __containerof(ctx, struct nh_control, ctl_epoch_ctx);
destroy_ctl(ctl);
}
void
nhops_destroy_rib(struct rib_head *rh)
{
struct nh_control *ctl;
struct nhop_priv *nh_priv;
ctl = rh->nh_control;
/*
* All routes should have been deleted in rt_table_destroy().
* However, TCP stack or other consumers may store referenced
* nexthop pointers. When these references go to zero,
* nhop_free() will try to unlink these records from the
* datastructures, most likely leading to panic.
*
* Avoid that by explicitly marking all of the remaining
* nexthops as unlinked by removing a reference from a special
* counter. Please see nhop_free() comments for more
* details.
*/
NHOPS_WLOCK(ctl);
CHT_SLIST_FOREACH(&ctl->nh_head, nhops, nh_priv) {
FIB_RH_LOG(LOG_DEBUG3, rh, "marking nhop %u unlinked", nh_priv->nh_idx);
refcount_release(&nh_priv->nh_linked);
} CHT_SLIST_FOREACH_END;
#ifdef ROUTE_MPATH
nhgrp_ctl_unlink_all(ctl);
#endif
NHOPS_WUNLOCK(ctl);
/*
* Postpone destruction till the end of current epoch
* so nhop_free() can safely use nh_control pointer.
*/
NET_EPOCH_CALL(destroy_ctl_epoch, &ctl->ctl_epoch_ctx);
}
/*
* Nexhop hash calculation:
*
* Nexthops distribution:
* 2 "mandatory" nexthops per interface ("interface route", "loopback").
* For direct peering: 1 nexthop for the peering router per ifp/af.
* For Ix-like peering: tens to hundreds nexthops of neghbors per ifp/af.
* IGP control plane & broadcast segment: tens of nexthops per ifp/af.
*
* Each fib/af combination has its own hash table.
* With that in mind, hash nexthops by the combination of the interface
* and GW IP address.
*
* To optimize hash calculation, ignore lower bits of ifnet pointer,
* as they give very little entropy.
* Similarly, use lower 4 bytes of IPv6 address to distinguish between the
* neighbors.
*/
struct _hash_data {
uint16_t ifentropy;
uint8_t family;
uint8_t nh_type;
uint32_t gw_addr;
};
static unsigned
djb_hash(const unsigned char *h, const int len)
{
unsigned int result = 0;
int i;
for (i = 0; i < len; i++)
result = 33 * result ^ h[i];
return (result);
}
static uint32_t
hash_priv(const struct nhop_priv *priv)
{
struct nhop_object *nh = priv->nh;
struct _hash_data key = {
.ifentropy = (uint16_t)((((uintptr_t)nh->nh_ifp) >> 6) & 0xFFFF),
.family = nh->gw_sa.sa_family,
.nh_type = priv->nh_type & 0xFF,
.gw_addr = (nh->gw_sa.sa_family == AF_INET6) ?
nh->gw6_sa.sin6_addr.s6_addr32[3] :
nh->gw4_sa.sin_addr.s_addr
};
return (uint32_t)(djb_hash((const unsigned char *)&key, sizeof(key)));
}
/*
* Checks if hash needs resizing and performs this resize if necessary
*
*/
static void
consider_resize(struct nh_control *ctl, uint32_t new_nh_buckets, uint32_t new_idx_items)
{
void *nh_ptr, *nh_idx_ptr;
void *old_idx_ptr;
size_t alloc_size;
nh_ptr = NULL;
if (new_nh_buckets != 0) {
alloc_size = CHT_SLIST_GET_RESIZE_SIZE(new_nh_buckets);
nh_ptr = malloc(alloc_size, M_NHOP, M_NOWAIT | M_ZERO);
}
nh_idx_ptr = NULL;
if (new_idx_items != 0) {
alloc_size = bitmask_get_size(new_idx_items);
nh_idx_ptr = malloc(alloc_size, M_NHOP, M_NOWAIT | M_ZERO);
}
if (nh_ptr == NULL && nh_idx_ptr == NULL) {
/* Either resize is not required or allocations have failed. */
return;
}
FIB_CTL_LOG(LOG_DEBUG, ctl,
"going to resize: nh:[ptr:%p sz:%u] idx:[ptr:%p sz:%u]",
nh_ptr, new_nh_buckets, nh_idx_ptr, new_idx_items);
old_idx_ptr = NULL;
NHOPS_WLOCK(ctl);
if (nh_ptr != NULL) {
CHT_SLIST_RESIZE(&ctl->nh_head, nhops, nh_ptr, new_nh_buckets);
}
if (nh_idx_ptr != NULL) {
if (bitmask_copy(&ctl->nh_idx_head, nh_idx_ptr, new_idx_items) == 0)
bitmask_swap(&ctl->nh_idx_head, nh_idx_ptr, new_idx_items, &old_idx_ptr);
}
NHOPS_WUNLOCK(ctl);
if (nh_ptr != NULL)
free(nh_ptr, M_NHOP);
if (old_idx_ptr != NULL)
free(old_idx_ptr, M_NHOP);
}
/*
* Links nextop @nh_priv to the nexhop hash table and allocates
* nexhop index.
* Returns allocated index or 0 on failure.
*/
int
link_nhop(struct nh_control *ctl, struct nhop_priv *nh_priv)
{
uint16_t idx;
uint32_t num_buckets_new, num_items_new;
KASSERT((nh_priv->nh_idx == 0), ("nhop index is already allocated"));
NHOPS_WLOCK(ctl);
/*
* Check if we need to resize hash and index.
* The following 2 functions returns either new size or 0
* if resize is not required.
*/
num_buckets_new = CHT_SLIST_GET_RESIZE_BUCKETS(&ctl->nh_head);
num_items_new = bitmask_get_resize_items(&ctl->nh_idx_head);
if (bitmask_alloc_idx(&ctl->nh_idx_head, &idx) != 0) {
NHOPS_WUNLOCK(ctl);
FIB_CTL_LOG(LOG_INFO, ctl, "Unable to allocate nhop index");
RTSTAT_INC(rts_nh_idx_alloc_failure);
consider_resize(ctl, num_buckets_new, num_items_new);
return (0);
}
nh_priv->nh_idx = idx;
nh_priv->nh_control = ctl;
nh_priv->nh_finalized = 1;
CHT_SLIST_INSERT_HEAD(&ctl->nh_head, nhops, nh_priv);
NHOPS_WUNLOCK(ctl);
FIB_RH_LOG(LOG_DEBUG2, ctl->ctl_rh,
"Linked nhop priv %p to %d, hash %u, ctl %p",
nh_priv, idx, hash_priv(nh_priv), ctl);
consider_resize(ctl, num_buckets_new, num_items_new);
return (idx);
}
/*
* Unlinks nexthop specified by @nh_priv data from the hash.
*
* Returns found nexthop or NULL.
*/
struct nhop_priv *
unlink_nhop(struct nh_control *ctl, struct nhop_priv *nh_priv_del)
{
struct nhop_priv *priv_ret;
int idx;
uint32_t num_buckets_new, num_items_new;
idx = 0;
NHOPS_WLOCK(ctl);
CHT_SLIST_REMOVE(&ctl->nh_head, nhops, nh_priv_del, priv_ret);
if (priv_ret != NULL) {
idx = priv_ret->nh_idx;
priv_ret->nh_idx = 0;
KASSERT((idx != 0), ("bogus nhop index 0"));
if ((bitmask_free_idx(&ctl->nh_idx_head, idx)) != 0) {
FIB_CTL_LOG(LOG_DEBUG, ctl,
"Unable to remove index %d from fib %u af %d",
idx, ctl->ctl_rh->rib_fibnum, ctl->ctl_rh->rib_family);
}
}
/* Check if hash or index needs to be resized */
num_buckets_new = CHT_SLIST_GET_RESIZE_BUCKETS(&ctl->nh_head);
num_items_new = bitmask_get_resize_items(&ctl->nh_idx_head);
NHOPS_WUNLOCK(ctl);
if (priv_ret == NULL) {
FIB_CTL_LOG(LOG_INFO, ctl,
"Unable to unlink nhop priv %p from hash, hash %u ctl %p",
nh_priv_del, hash_priv(nh_priv_del), ctl);
} else {
FIB_CTL_LOG(LOG_DEBUG2, ctl, "Unlinked nhop %p priv idx %d",
priv_ret, idx);
}
consider_resize(ctl, num_buckets_new, num_items_new);
return (priv_ret);
}
/*
* Searches for the nexthop by data specifcied in @nh_priv.
* Returns referenced nexthop or NULL.
*/
struct nhop_priv *
find_nhop(struct nh_control *ctl, const struct nhop_priv *nh_priv)
{
struct nhop_priv *nh_priv_ret;
NHOPS_RLOCK(ctl);
CHT_SLIST_FIND_BYOBJ(&ctl->nh_head, nhops, nh_priv, nh_priv_ret);
if (nh_priv_ret != NULL) {
if (refcount_acquire_if_not_zero(&nh_priv_ret->nh_refcnt) == 0){
/* refcount was 0 -> nhop is being deleted */
nh_priv_ret = NULL;
}
}
NHOPS_RUNLOCK(ctl);
return (nh_priv_ret);
}
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