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freebsd-dev/sys/netinet/ip_encap.c
Andrey V. Elsukov 6d8fdfa9d5 Rework IP encapsulation handling code. 
Currently it has several disadvantages:
- it uses single mutex to protect internal structures. It is used by
  data- and control- path, thus there are no parallelism at all.
- it uses single list to keep encap handlers for both INET and INET6
  families.
- struct encaptab keeps unneeded information (src, dst, masks, protosw),
  that isn't used by code in the source tree.
- matches are prioritized and when many tunneling interfaces are
  registered, encapcheck handler of each interface is invoked for each
  packet. The search takes O(n) for n interfaces. All this work is done
  with exclusive lock held.

What this patch includes:
- the datapath is converted to be lockless using epoch(9) KPI.
- struct encaptab now linked using CK_LIST.
- all unused fields removed from struct encaptab. Several new fields
  addedr: min_length is the minimum packet length, that encapsulation
  handler expects to see; exact_match is maximum number of bits, that
  can return an encapsulation handler, when it wants to consume a packet.
- IPv6 and IPv4 handlers are stored in separate lists;
- added new "encap_lookup_t" method, that will be used later. It is
  targeted to speedup lookup of needed interface, when gif(4)/gre(4) have
  many interfaces.
- the need to use protosw structure is eliminated. The only pr_input
  method was used from this structure, so I don't see the need to keep
  using it.
- encap_input_t method changed to avoid using mbuf tags to store softc
  pointer. Now it is passed directly trough encap_input_t method.
  encap_getarg() funtions is removed.
- all sockaddr structures and code that uses them removed. We don't have
  any code in the tree that uses them. All consumers use encap_attach_func()
  method, that relies on invoking of encapcheck() to determine the needed
  handler.
- introduced struct encap_config, it contains parameters of encap handler
  that is going to be registered by encap_attach() function.
- encap handlers are stored in lists ordered by exact_match value, thus
  handlers that need more bits to match will be checked first, and if
  encapcheck method returns exact_match value, the search will be stopped.
- all current consumers changed to use new KPI.

Reviewed by:	mmacy
Sponsored by:	Yandex LLC
Differential Revision:	https://reviews.freebsd.org/D15617
2018-06-05 20:51:01 +00:00

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/* $KAME: ip_encap.c,v 1.41 2001/03/15 08:35:08 itojun Exp $ */
/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
* Copyright (c) 2018 Andrey V. Elsukov <ae@FreeBSD.org>
* All rights reserved.
*
* 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.
* 3. Neither the name of the project nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE PROJECT 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 PROJECT 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.
*/
/*
* My grandfather said that there's a devil inside tunnelling technology...
*
* We have surprisingly many protocols that want packets with IP protocol
* #4 or #41. Here's a list of protocols that want protocol #41:
* RFC1933 configured tunnel
* RFC1933 automatic tunnel
* RFC2401 IPsec tunnel
* RFC2473 IPv6 generic packet tunnelling
* RFC2529 6over4 tunnel
* mobile-ip6 (uses RFC2473)
* RFC3056 6to4 tunnel
* isatap tunnel
* Here's a list of protocol that want protocol #4:
* RFC1853 IPv4-in-IPv4 tunnelling
* RFC2003 IPv4 encapsulation within IPv4
* RFC2344 reverse tunnelling for mobile-ip4
* RFC2401 IPsec tunnel
* Well, what can I say. They impose different en/decapsulation mechanism
* from each other, so they need separate protocol handler. The only one
* we can easily determine by protocol # is IPsec, which always has
* AH/ESP/IPComp header right after outer IP header.
*
* So, clearly good old protosw does not work for protocol #4 and #41.
* The code will let you match protocol via src/dst address pair.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_inet.h"
#include "opt_inet6.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/mbuf.h>
#include <sys/errno.h>
#include <sys/socket.h>
#include <net/if.h>
#include <net/if_var.h>
#include <netinet/in.h>
#include <netinet/ip_var.h>
#include <netinet/ip_encap.h>
#ifdef INET6
#include <netinet6/ip6_var.h>
#endif
static MALLOC_DEFINE(M_NETADDR, "encap_export_host",
"Export host address structure");
struct encaptab {
CK_LIST_ENTRY(encaptab) chain;
int proto;
int min_length;
int exact_match;
void *arg;
encap_lookup_t lookup;
encap_check_t check;
encap_input_t input;
};
CK_LIST_HEAD(encaptab_head, encaptab);
#ifdef INET
static struct encaptab_head ipv4_encaptab = CK_LIST_HEAD_INITIALIZER();
#endif
#ifdef INET6
static struct encaptab_head ipv6_encaptab = CK_LIST_HEAD_INITIALIZER();
#endif
static struct mtx encapmtx;
MTX_SYSINIT(encapmtx, &encapmtx, "encapmtx", MTX_DEF);
#define ENCAP_WLOCK() mtx_lock(&encapmtx)
#define ENCAP_WUNLOCK() mtx_unlock(&encapmtx)
#define ENCAP_RLOCK() epoch_enter_preempt(net_epoch_preempt)
#define ENCAP_RUNLOCK() epoch_exit_preempt(net_epoch_preempt)
#define ENCAP_WAIT() epoch_wait_preempt(net_epoch_preempt)
static struct encaptab *
encap_attach(struct encaptab_head *head, const struct encap_config *cfg,
void *arg, int mflags)
{
struct encaptab *ep, *tmp;
if (cfg == NULL || cfg->input == NULL ||
(cfg->check == NULL && cfg->lookup == NULL) ||
(cfg->lookup != NULL && cfg->exact_match != ENCAP_DRV_LOOKUP) ||
(cfg->exact_match == ENCAP_DRV_LOOKUP && cfg->lookup == NULL))
return (NULL);
ep = malloc(sizeof(*ep), M_NETADDR, mflags);
if (ep == NULL)
return (NULL);
ep->proto = cfg->proto;
ep->min_length = cfg->min_length;
ep->exact_match = cfg->exact_match;
ep->arg = arg;
ep->lookup = cfg->exact_match == ENCAP_DRV_LOOKUP ? cfg->lookup: NULL;
ep->check = cfg->exact_match != ENCAP_DRV_LOOKUP ? cfg->check: NULL;
ep->input = cfg->input;
ENCAP_WLOCK();
CK_LIST_FOREACH(tmp, head, chain) {
if (tmp->exact_match <= ep->exact_match)
break;
}
if (tmp == NULL)
CK_LIST_INSERT_HEAD(head, ep, chain);
else
CK_LIST_INSERT_BEFORE(tmp, ep, chain);
ENCAP_WUNLOCK();
return (ep);
}
static int
encap_detach(struct encaptab_head *head, const struct encaptab *cookie)
{
struct encaptab *ep;
ENCAP_WLOCK();
CK_LIST_FOREACH(ep, head, chain) {
if (ep == cookie) {
CK_LIST_REMOVE(ep, chain);
ENCAP_WUNLOCK();
ENCAP_WAIT();
free(ep, M_NETADDR);
return (0);
}
}
ENCAP_WUNLOCK();
return (EINVAL);
}
static int
encap_input(struct encaptab_head *head, struct mbuf *m, int off, int proto)
{
struct encaptab *ep, *match;
void *arg;
int matchprio, ret;
match = NULL;
matchprio = 0;
ENCAP_RLOCK();
CK_LIST_FOREACH(ep, head, chain) {
if (ep->proto >= 0 && ep->proto != proto)
continue;
if (ep->min_length > m->m_pkthdr.len)
continue;
if (ep->exact_match == ENCAP_DRV_LOOKUP)
ret = (*ep->lookup)(m, off, proto, &arg);
else
ret = (*ep->check)(m, off, proto, ep->arg);
if (ret <= 0)
continue;
if (ret > matchprio) {
match = ep;
if (ep->exact_match != ENCAP_DRV_LOOKUP)
arg = ep->arg;
/*
* No need to continue the search, we got the
* exact match.
*/
if (ret >= ep->exact_match)
break;
matchprio = ret;
}
}
if (match != NULL) {
/* found a match, "match" has the best one */
ret = (*match->input)(m, off, proto, arg);
ENCAP_RUNLOCK();
MPASS(ret == IPPROTO_DONE);
return (IPPROTO_DONE);
}
ENCAP_RUNLOCK();
return (0);
}
#ifdef INET
const struct encaptab *
ip_encap_attach(const struct encap_config *cfg, void *arg, int mflags)
{
return (encap_attach(&ipv4_encaptab, cfg, arg, mflags));
}
int
ip_encap_detach(const struct encaptab *cookie)
{
return (encap_detach(&ipv4_encaptab, cookie));
}
int
encap4_input(struct mbuf **mp, int *offp, int proto)
{
if (encap_input(&ipv4_encaptab, *mp, *offp, proto) != IPPROTO_DONE)
return (rip_input(mp, offp, proto));
return (IPPROTO_DONE);
}
#endif /* INET */
#ifdef INET6
const struct encaptab *
ip6_encap_attach(const struct encap_config *cfg, void *arg, int mflags)
{
return (encap_attach(&ipv6_encaptab, cfg, arg, mflags));
}
int
ip6_encap_detach(const struct encaptab *cookie)
{
return (encap_detach(&ipv6_encaptab, cookie));
}
int
encap6_input(struct mbuf **mp, int *offp, int proto)
{
if (encap_input(&ipv6_encaptab, *mp, *offp, proto) != IPPROTO_DONE)
return (rip6_input(mp, offp, proto));
return (IPPROTO_DONE);
}
#endif /* INET6 */
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