NetBSD/sys/netinet/ip_flow.c

686 lines
16 KiB
C

/* $NetBSD: ip_flow.c,v 1.85 2021/02/19 14:51:59 christos Exp $ */
/*-
* Copyright (c) 1998 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by the 3am Software Foundry ("3am"). It was developed by Matt Thomas.
*
* 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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>
__KERNEL_RCSID(0, "$NetBSD: ip_flow.c,v 1.85 2021/02/19 14:51:59 christos Exp $");
#ifdef _KERNEL_OPT
#include "opt_net_mpsafe.h"
#endif
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socketvar.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/pool.h>
#include <sys/sysctl.h>
#include <sys/workqueue.h>
#include <sys/atomic.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/route.h>
#include <net/pfil.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/ip_private.h>
/*
* Similar code is very well commented in netinet6/ip6_flow.c
*/
#define IPFLOW_HASHBITS 6 /* should not be a multiple of 8 */
static struct pool ipflow_pool;
TAILQ_HEAD(ipflowhead, ipflow);
#define IPFLOW_TIMER (5 * PR_SLOWHZ)
#define IPFLOW_DEFAULT_HASHSIZE (1 << IPFLOW_HASHBITS)
/*
* ip_flow.c internal lock.
* If we use softnet_lock, it would cause recursive lock.
*
* This is a tentative workaround.
* We should make it scalable somehow in the future.
*/
static kmutex_t ipflow_lock;
static struct ipflowhead *ipflowtable = NULL;
static struct ipflowhead ipflowlist;
static int ipflow_inuse;
#define IPFLOW_INSERT(hashidx, ipf) \
do { \
(ipf)->ipf_hashidx = (hashidx); \
TAILQ_INSERT_HEAD(&ipflowtable[(hashidx)], (ipf), ipf_hash); \
TAILQ_INSERT_HEAD(&ipflowlist, (ipf), ipf_list); \
} while (/*CONSTCOND*/ 0)
#define IPFLOW_REMOVE(hashidx, ipf) \
do { \
TAILQ_REMOVE(&ipflowtable[(hashidx)], (ipf), ipf_hash); \
TAILQ_REMOVE(&ipflowlist, (ipf), ipf_list); \
} while (/*CONSTCOND*/ 0)
#ifndef IPFLOW_MAX
#define IPFLOW_MAX 256
#endif
static int ip_maxflows = IPFLOW_MAX;
static int ip_hashsize = IPFLOW_DEFAULT_HASHSIZE;
static struct ipflow *ipflow_reap(bool);
static void ipflow_sysctl_init(struct sysctllog **);
static void ipflow_slowtimo_work(struct work *, void *);
static struct workqueue *ipflow_slowtimo_wq;
static struct work ipflow_slowtimo_wk;
static size_t
ipflow_hash(const struct ip *ip)
{
size_t hash = ip->ip_tos;
size_t idx;
for (idx = 0; idx < 32; idx += IPFLOW_HASHBITS) {
hash += (ip->ip_dst.s_addr >> (32 - idx)) +
(ip->ip_src.s_addr >> idx);
}
return hash & (ip_hashsize-1);
}
static struct ipflow *
ipflow_lookup(const struct ip *ip)
{
size_t hash;
struct ipflow *ipf;
KASSERT(mutex_owned(&ipflow_lock));
hash = ipflow_hash(ip);
TAILQ_FOREACH(ipf, &ipflowtable[hash], ipf_hash) {
if (ip->ip_dst.s_addr == ipf->ipf_dst.s_addr
&& ip->ip_src.s_addr == ipf->ipf_src.s_addr
&& ip->ip_tos == ipf->ipf_tos)
break;
}
return ipf;
}
void
ipflow_poolinit(void)
{
pool_init(&ipflow_pool, sizeof(struct ipflow), 0, 0, 0, "ipflowpl",
NULL, IPL_NET);
}
static int
ipflow_reinit(int table_size)
{
struct ipflowhead *new_table;
size_t i;
KASSERT(mutex_owned(&ipflow_lock));
new_table = (struct ipflowhead *)malloc(sizeof(struct ipflowhead) *
table_size, M_RTABLE, M_NOWAIT);
if (new_table == NULL)
return 1;
if (ipflowtable != NULL)
free(ipflowtable, M_RTABLE);
ipflowtable = new_table;
ip_hashsize = table_size;
TAILQ_INIT(&ipflowlist);
for (i = 0; i < ip_hashsize; i++)
TAILQ_INIT(&ipflowtable[i]);
return 0;
}
void
ipflow_init(void)
{
int error;
error = workqueue_create(&ipflow_slowtimo_wq, "ipflow_slowtimo",
ipflow_slowtimo_work, NULL, PRI_SOFTNET, IPL_SOFTNET, WQ_MPSAFE);
if (error != 0)
panic("%s: workqueue_create failed (%d)\n", __func__, error);
mutex_init(&ipflow_lock, MUTEX_DEFAULT, IPL_NONE);
mutex_enter(&ipflow_lock);
(void)ipflow_reinit(ip_hashsize);
mutex_exit(&ipflow_lock);
ipflow_sysctl_init(NULL);
}
int
ipflow_fastforward(struct mbuf *m)
{
struct ip *ip;
struct ip ip_store;
struct ipflow *ipf;
struct rtentry *rt = NULL;
const struct sockaddr *dst;
int error;
int iplen;
struct ifnet *ifp;
int s;
int ret = 0;
mutex_enter(&ipflow_lock);
/*
* Are we forwarding packets? Big enough for an IP packet?
*/
if (!ipforwarding || ipflow_inuse == 0 || m->m_len < sizeof(struct ip))
goto out;
/*
* Was packet received as a link-level multicast or broadcast?
* If so, don't try to fast forward..
*/
if ((m->m_flags & (M_BCAST|M_MCAST)) != 0)
goto out;
/*
* IP header with no option and valid version and length
*/
ip = mtod(m, struct ip *);
if (!ACCESSIBLE_POINTER(ip, struct ip)) {
memcpy(&ip_store, mtod(m, const void *), sizeof(ip_store));
ip = &ip_store;
}
iplen = ntohs(ip->ip_len);
if (ip->ip_v != IPVERSION || ip->ip_hl != (sizeof(struct ip) >> 2) ||
iplen < sizeof(struct ip) || iplen > m->m_pkthdr.len)
goto out;
/*
* Find a flow.
*/
if ((ipf = ipflow_lookup(ip)) == NULL)
goto out;
ifp = m_get_rcvif(m, &s);
if (__predict_false(ifp == NULL))
goto out_unref;
/*
* Verify the IP header checksum.
*/
switch (m->m_pkthdr.csum_flags &
((ifp->if_csum_flags_rx & M_CSUM_IPv4) |
M_CSUM_IPv4_BAD)) {
case M_CSUM_IPv4|M_CSUM_IPv4_BAD:
m_put_rcvif(ifp, &s);
goto out_unref;
case M_CSUM_IPv4:
/* Checksum was okay. */
break;
default:
/* Must compute it ourselves. */
if (in_cksum(m, sizeof(struct ip)) != 0) {
m_put_rcvif(ifp, &s);
goto out_unref;
}
break;
}
m_put_rcvif(ifp, &s);
/*
* Route and interface still up?
*/
rt = rtcache_validate(&ipf->ipf_ro);
if (rt == NULL || (rt->rt_ifp->if_flags & IFF_UP) == 0 ||
(rt->rt_flags & (RTF_BLACKHOLE | RTF_BROADCAST)) != 0)
goto out_unref;
/*
* Packet size OK? TTL?
*/
if (m->m_pkthdr.len > rt->rt_ifp->if_mtu || ip->ip_ttl <= IPTTLDEC)
goto out_unref;
/*
* Clear any in-bound checksum flags for this packet.
*/
m->m_pkthdr.csum_flags = 0;
/*
* Everything checks out and so we can forward this packet.
* Modify the TTL and incrementally change the checksum.
*
* This method of adding the checksum works on either endian CPU.
* If htons() is inlined, all the arithmetic is folded; otherwise
* the htons()s are combined by CSE due to the const attribute.
*
* Don't bother using HW checksumming here -- the incremental
* update is pretty fast.
*/
ip->ip_ttl -= IPTTLDEC;
if (ip->ip_sum >= (u_int16_t) ~htons(IPTTLDEC << 8))
ip->ip_sum -= ~htons(IPTTLDEC << 8);
else
ip->ip_sum += htons(IPTTLDEC << 8);
/*
* Done modifying the header; copy it back, if necessary.
*
* XXX Use m_copyback_cow(9) here? --dyoung
*/
if (!ACCESSIBLE_POINTER(mtod(m, void *), struct ip))
memcpy(mtod(m, void *), &ip_store, sizeof(ip_store));
/*
* Trim the packet in case it's too long..
*/
if (m->m_pkthdr.len > iplen) {
if (m->m_len == m->m_pkthdr.len) {
m->m_len = iplen;
m->m_pkthdr.len = iplen;
} else
m_adj(m, iplen - m->m_pkthdr.len);
}
/*
* Send the packet on its way. All we can get back is ENOBUFS
*/
ipf->ipf_uses++;
#if 0
/*
* Sorting list is too heavy for fast path(packet processing path).
* It degrades about 10% performance. So, we does not sort ipflowtable,
* and then we use FIFO cache replacement instead fo LRU.
*/
/* move to head (LRU) for ipflowlist. ipflowtable ooes not care LRU. */
TAILQ_REMOVE(&ipflowlist, ipf, ipf_list);
TAILQ_INSERT_HEAD(&ipflowlist, ipf, ipf_list);
#endif
PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER);
if (rt->rt_flags & RTF_GATEWAY)
dst = rt->rt_gateway;
else
dst = rtcache_getdst(&ipf->ipf_ro);
if ((error = if_output_lock(rt->rt_ifp, rt->rt_ifp, m, dst, rt)) != 0) {
if (error == ENOBUFS)
ipf->ipf_dropped++;
else
ipf->ipf_errors++;
}
ret = 1;
out_unref:
rtcache_unref(rt, &ipf->ipf_ro);
out:
mutex_exit(&ipflow_lock);
return ret;
}
static void
ipflow_addstats(struct ipflow *ipf)
{
struct rtentry *rt;
uint64_t *ips;
rt = rtcache_validate(&ipf->ipf_ro);
if (rt != NULL) {
rt->rt_use += ipf->ipf_uses;
rtcache_unref(rt, &ipf->ipf_ro);
}
ips = IP_STAT_GETREF();
ips[IP_STAT_CANTFORWARD] += ipf->ipf_errors + ipf->ipf_dropped;
ips[IP_STAT_TOTAL] += ipf->ipf_uses;
ips[IP_STAT_FORWARD] += ipf->ipf_uses;
ips[IP_STAT_FASTFORWARD] += ipf->ipf_uses;
IP_STAT_PUTREF();
}
static void
ipflow_free(struct ipflow *ipf)
{
KASSERT(mutex_owned(&ipflow_lock));
/*
* Remove the flow from the hash table (at elevated IPL).
* Once it's off the list, we can deal with it at normal
* network IPL.
*/
IPFLOW_REMOVE(ipf->ipf_hashidx, ipf);
ipflow_addstats(ipf);
rtcache_free(&ipf->ipf_ro);
ipflow_inuse--;
pool_put(&ipflow_pool, ipf);
}
static struct ipflow *
ipflow_reap(bool just_one)
{
struct ipflow *ipf;
KASSERT(mutex_owned(&ipflow_lock));
/*
* This case must remove one ipflow. Furthermore, this case is used in
* fast path(packet processing path). So, simply remove TAILQ_LAST one.
*/
if (just_one) {
ipf = TAILQ_LAST(&ipflowlist, ipflowhead);
KASSERT(ipf != NULL);
IPFLOW_REMOVE(ipf->ipf_hashidx, ipf);
ipflow_addstats(ipf);
rtcache_free(&ipf->ipf_ro);
return ipf;
}
/*
* This case is used in slow path(sysctl).
* At first, remove invalid rtcache ipflow, and then remove TAILQ_LAST
* ipflow if it is ensured least recently used by comparing last_uses.
*/
while (ipflow_inuse > ip_maxflows) {
struct ipflow *maybe_ipf = TAILQ_LAST(&ipflowlist, ipflowhead);
TAILQ_FOREACH(ipf, &ipflowlist, ipf_list) {
struct rtentry *rt;
/*
* If this no longer points to a valid route
* reclaim it.
*/
rt = rtcache_validate(&ipf->ipf_ro);
if (rt == NULL)
goto done;
rtcache_unref(rt, &ipf->ipf_ro);
/*
* choose the one that's been least recently
* used or has had the least uses in the
* last 1.5 intervals.
*/
if (ipf->ipf_timer < maybe_ipf->ipf_timer
|| ((ipf->ipf_timer == maybe_ipf->ipf_timer)
&& (ipf->ipf_last_uses + ipf->ipf_uses
< maybe_ipf->ipf_last_uses + maybe_ipf->ipf_uses)))
maybe_ipf = ipf;
}
ipf = maybe_ipf;
done:
/*
* Remove the entry from the flow table.
*/
IPFLOW_REMOVE(ipf->ipf_hashidx, ipf);
ipflow_addstats(ipf);
rtcache_free(&ipf->ipf_ro);
pool_put(&ipflow_pool, ipf);
ipflow_inuse--;
}
return NULL;
}
static unsigned int ipflow_work_enqueued = 0;
static void
ipflow_slowtimo_work(struct work *wk, void *arg)
{
struct rtentry *rt;
struct ipflow *ipf, *next_ipf;
uint64_t *ips;
/* We can allow enqueuing another work at this point */
atomic_swap_uint(&ipflow_work_enqueued, 0);
SOFTNET_KERNEL_LOCK_UNLESS_NET_MPSAFE();
mutex_enter(&ipflow_lock);
for (ipf = TAILQ_FIRST(&ipflowlist); ipf != NULL; ipf = next_ipf) {
next_ipf = TAILQ_NEXT(ipf, ipf_list);
if (PRT_SLOW_ISEXPIRED(ipf->ipf_timer) ||
(rt = rtcache_validate(&ipf->ipf_ro)) == NULL) {
ipflow_free(ipf);
} else {
ipf->ipf_last_uses = ipf->ipf_uses;
rt->rt_use += ipf->ipf_uses;
rtcache_unref(rt, &ipf->ipf_ro);
ips = IP_STAT_GETREF();
ips[IP_STAT_TOTAL] += ipf->ipf_uses;
ips[IP_STAT_FORWARD] += ipf->ipf_uses;
ips[IP_STAT_FASTFORWARD] += ipf->ipf_uses;
IP_STAT_PUTREF();
ipf->ipf_uses = 0;
}
}
mutex_exit(&ipflow_lock);
SOFTNET_KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
}
void
ipflow_slowtimo(void)
{
/* Avoid enqueuing another work when one is already enqueued */
if (atomic_swap_uint(&ipflow_work_enqueued, 1) == 1)
return;
workqueue_enqueue(ipflow_slowtimo_wq, &ipflow_slowtimo_wk, NULL);
}
void
ipflow_create(struct route *ro, struct mbuf *m)
{
const struct ip *const ip = mtod(m, const struct ip *);
struct ipflow *ipf;
size_t hash;
KERNEL_LOCK_UNLESS_NET_MPSAFE();
mutex_enter(&ipflow_lock);
/*
* Don't create cache entries for ICMP messages.
*/
if (ip_maxflows == 0 || ip->ip_p == IPPROTO_ICMP)
goto out;
/*
* See if an existing flow struct exists. If so remove it from its
* list and free the old route. If not, try to malloc a new one
* (if we aren't at our limit).
*/
ipf = ipflow_lookup(ip);
if (ipf == NULL) {
if (ipflow_inuse >= ip_maxflows) {
ipf = ipflow_reap(true);
} else {
ipf = pool_get(&ipflow_pool, PR_NOWAIT);
if (ipf == NULL)
goto out;
ipflow_inuse++;
}
memset(ipf, 0, sizeof(*ipf));
} else {
IPFLOW_REMOVE(ipf->ipf_hashidx, ipf);
ipflow_addstats(ipf);
rtcache_free(&ipf->ipf_ro);
ipf->ipf_uses = ipf->ipf_last_uses = 0;
ipf->ipf_errors = ipf->ipf_dropped = 0;
}
/*
* Fill in the updated information.
*/
rtcache_copy(&ipf->ipf_ro, ro);
ipf->ipf_dst = ip->ip_dst;
ipf->ipf_src = ip->ip_src;
ipf->ipf_tos = ip->ip_tos;
PRT_SLOW_ARM(ipf->ipf_timer, IPFLOW_TIMER);
/*
* Insert into the approriate bucket of the flow table.
*/
hash = ipflow_hash(ip);
IPFLOW_INSERT(hash, ipf);
out:
mutex_exit(&ipflow_lock);
KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
}
int
ipflow_invalidate_all(int new_size)
{
struct ipflow *ipf, *next_ipf;
int error;
error = 0;
mutex_enter(&ipflow_lock);
for (ipf = TAILQ_FIRST(&ipflowlist); ipf != NULL; ipf = next_ipf) {
next_ipf = TAILQ_NEXT(ipf, ipf_list);
ipflow_free(ipf);
}
if (new_size)
error = ipflow_reinit(new_size);
mutex_exit(&ipflow_lock);
return error;
}
/*
* sysctl helper routine for net.inet.ip.maxflows.
*/
static int
sysctl_net_inet_ip_maxflows(SYSCTLFN_ARGS)
{
int error;
error = sysctl_lookup(SYSCTLFN_CALL(rnode));
if (error || newp == NULL)
return (error);
SOFTNET_KERNEL_LOCK_UNLESS_NET_MPSAFE();
mutex_enter(&ipflow_lock);
ipflow_reap(false);
mutex_exit(&ipflow_lock);
SOFTNET_KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
return (0);
}
static int
sysctl_net_inet_ip_hashsize(SYSCTLFN_ARGS)
{
int error, tmp;
struct sysctlnode node;
node = *rnode;
tmp = ip_hashsize;
node.sysctl_data = &tmp;
error = sysctl_lookup(SYSCTLFN_CALL(&node));
if (error || newp == NULL)
return (error);
if ((tmp & (tmp - 1)) == 0 && tmp != 0) {
/*
* Can only fail due to malloc()
*/
SOFTNET_KERNEL_LOCK_UNLESS_NET_MPSAFE();
error = ipflow_invalidate_all(tmp);
SOFTNET_KERNEL_UNLOCK_UNLESS_NET_MPSAFE();
} else {
/*
* EINVAL if not a power of 2
*/
error = EINVAL;
}
return error;
}
static void
ipflow_sysctl_init(struct sysctllog **clog)
{
sysctl_createv(clog, 0, NULL, NULL,
CTLFLAG_PERMANENT,
CTLTYPE_NODE, "inet",
SYSCTL_DESCR("PF_INET related settings"),
NULL, 0, NULL, 0,
CTL_NET, PF_INET, CTL_EOL);
sysctl_createv(clog, 0, NULL, NULL,
CTLFLAG_PERMANENT,
CTLTYPE_NODE, "ip",
SYSCTL_DESCR("IPv4 related settings"),
NULL, 0, NULL, 0,
CTL_NET, PF_INET, IPPROTO_IP, CTL_EOL);
sysctl_createv(clog, 0, NULL, NULL,
CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
CTLTYPE_INT, "maxflows",
SYSCTL_DESCR("Number of flows for fast forwarding"),
sysctl_net_inet_ip_maxflows, 0, &ip_maxflows, 0,
CTL_NET, PF_INET, IPPROTO_IP,
IPCTL_MAXFLOWS, CTL_EOL);
sysctl_createv(clog, 0, NULL, NULL,
CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
CTLTYPE_INT, "hashsize",
SYSCTL_DESCR("Size of hash table for fast forwarding (IPv4)"),
sysctl_net_inet_ip_hashsize, 0, &ip_hashsize, 0,
CTL_NET, PF_INET, IPPROTO_IP,
CTL_CREATE, CTL_EOL);
}