2da350beca
percpu(9) has a certain memory storage for each CPU and provides it by the piece to users. If the storages went short, percpu(9) enlarges them by allocating new larger memory areas, replacing old ones with them and destroying the old ones. A percpu storage referenced by a pointer gotten via percpu_getref can be destroyed by the mechanism after a running thread sleeps even if percpu_putref has not been called. Using rtcache, i.e., packet processing, typically involves sleepable operations such as rwlock so we must avoid dereferencing a rtcache that is directly stored in a percpu storage during packet processing. Address this situation by having just a pointer to a rtcache in a percpu storage instead. Reviewed by ozaki-r@ and yamaguchi@
211 lines
6.5 KiB
C
211 lines
6.5 KiB
C
/* $NetBSD: if_l2tp.h,v 1.8 2019/09/19 06:07:24 knakahara Exp $ */
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/*
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* Copyright (c) 2017 Internet Initiative Japan Inc.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* L2TPv3 kernel interface
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*/
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#ifndef _NET_IF_L2TP_H_
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#define _NET_IF_L2TP_H_
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#include <sys/queue.h>
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#include <sys/ioccom.h>
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#ifdef _KERNEL
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#include <sys/pserialize.h>
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#include <sys/psref.h>
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#include <sys/pslist.h>
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#endif
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#include <net/if_ether.h>
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#include <netinet/in.h>
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#define SIOCSL2TPSESSION _IOW('i', 151, struct l2tp_req)
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#define SIOCDL2TPSESSION _IOW('i', 152, struct l2tp_req)
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#define SIOCSL2TPCOOKIE _IOW('i', 153, struct l2tp_req)
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#define SIOCDL2TPCOOKIE _IOW('i', 154, struct l2tp_req)
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#define SIOCSL2TPSTATE _IOW('i', 155, struct l2tp_req)
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#define SIOCGL2TP SIOCGIFGENERIC
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struct l2tp_req {
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int state;
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u_int my_cookie_len;
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u_int peer_cookie_len;
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uint32_t my_sess_id;
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uint32_t peer_sess_id;
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uint64_t my_cookie;
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uint64_t peer_cookie;
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};
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#define L2TP_STATE_UP 1
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#define L2TP_STATE_DOWN 0
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#define L2TP_COOKIE_ON 1
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#define L2TP_COOKIE_OFF 0
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#ifdef _KERNEL
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extern struct psref_class *lv_psref_class;
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struct l2tp_variant {
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struct l2tp_softc *lv_softc;
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struct sockaddr *lv_psrc; /* Physical src addr */
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struct sockaddr *lv_pdst; /* Physical dst addr */
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const struct encaptab *lv_encap_cookie;
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/* L2TP session info */
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int lv_state;
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uint32_t lv_my_sess_id; /* my session ID */
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uint32_t lv_peer_sess_id; /* peer session ID */
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int lv_use_cookie;
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u_int lv_my_cookie_len;
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u_int lv_peer_cookie_len;
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uint64_t lv_my_cookie; /* my cookie */
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uint64_t lv_peer_cookie; /* peer cookie */
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struct psref_target lv_psref;
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};
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struct l2tp_softc {
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struct ethercom l2tp_ec; /* common area - must be at the top */
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/* to use ether_input(), we must have this */
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percpu_t *l2tp_ro_percpu; /* struct tunnel_ro */
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struct l2tp_variant *l2tp_var; /*
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* reader must use l2tp_getref_variant()
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* instead of direct dereference.
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*/
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kmutex_t l2tp_lock; /* writer lock for l2tp_var */
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pserialize_t l2tp_psz;
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void *l2tp_si;
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percpu_t *l2tp_ifq_percpu;
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LIST_ENTRY(l2tp_softc) l2tp_list; /* list of all l2tps */
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struct pslist_entry l2tp_hash; /* hashed list to lookup by session id */
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};
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#define L2TP_ROUTE_TTL 10
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#define L2TP_MTU (1280) /* Default MTU */
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#define L2TP_MTU_MIN (1280) /* Minimum MTU */
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#define L2TP_MTU_MAX (8192) /* Maximum MTU */
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/*
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* Get l2tp_variant from l2tp_softc.
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*
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* l2tp_variant itself is protected not to be freed by lv_psref.
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* In contrast, sc->sc_var can be changed to NULL even if reader critical
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* section. see l2tp_variant_update().
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* So, once a reader dereference sc->sc_var by this API, the reader must not
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* re-dereference form sc->sc_var.
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*/
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static __inline struct l2tp_variant *
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l2tp_getref_variant(struct l2tp_softc *sc, struct psref *psref)
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{
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struct l2tp_variant *var;
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int s;
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s = pserialize_read_enter();
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var = sc->l2tp_var;
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if (var == NULL) {
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pserialize_read_exit(s);
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return NULL;
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}
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membar_datadep_consumer();
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psref_acquire(psref, &var->lv_psref, lv_psref_class);
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pserialize_read_exit(s);
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return var;
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}
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static __inline void
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l2tp_putref_variant(struct l2tp_variant *var, struct psref *psref)
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{
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if (var == NULL)
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return;
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psref_release(psref, &var->lv_psref, lv_psref_class);
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}
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static __inline bool
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l2tp_heldref_variant(struct l2tp_variant *var)
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{
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return psref_held(&var->lv_psref, lv_psref_class);
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}
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/* Prototypes */
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void l2tpattach(int);
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int l2tpattach0(struct l2tp_softc *);
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void l2tp_input(struct mbuf *, struct ifnet *);
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int l2tp_ioctl(struct ifnet *, u_long, void *);
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struct l2tp_variant *l2tp_lookup_session_ref(uint32_t, struct psref *);
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int l2tp_check_nesting(struct ifnet *, struct mbuf *);
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/* TODO IP_TCPMSS support */
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#ifdef IP_TCPMSS
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struct mbuf *l2tp_tcpmss_clamp(struct ifnet *, struct mbuf *);
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#endif /* IP_TCPMSS */
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#endif /* _KERNEL */
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/*
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* Locking notes:
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* + l2tp_softc_list is protected by l2tp_list_lock (an adaptive mutex)
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* l2tp_softc_list is list of all l2tp_softcs, and it is used to avoid
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* unload while busy.
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* + l2tp_hashed_list is protected by
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* - l2tp_hash_lock (an adaptive mutex) for writer
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* - pserialize for reader
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* l2tp_hashed_list is hashed list of all l2tp_softcs, and it is used by
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* input processing to find appropriate softc.
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* + l2tp_softc->l2tp_var is protected by
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* - l2tp_softc->l2tp_lock (an adaptive mutex) for writer
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* - l2tp_var->lv_psref for reader
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* l2tp_softc->l2tp_var is used for variant values while the l2tp tunnel
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* exists.
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* + struct l2tp_ro->lr_ro is protected by struct tunnel_ro->tr_lock.
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* This lock is required to exclude softnet/0 lwp(such as output
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* processing softint) and processing lwp(such as DAD timer processing).
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*
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* Locking order:
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* - encap_lock => struct l2tp_softc->l2tp_lock
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* Other mutexes must not hold simultaneously.
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*
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* NOTICE
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* - l2tp_softc must not have a variant value while the l2tp tunnel exists.
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* Such variant values must be in l2tp_softc->l2tp_var.
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* - l2tp_softc->l2tp_var is modified like read-copy-update.
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* So, once we dereference l2tp_softc->l2tp_var, we must
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* keep the pointer during the same context. If we re-derefence
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* l2tp_softc->l2tp_var, the l2tp_var may be other one because of
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* concurrent writer processing.
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*/
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#endif /* _NET_IF_L2TP_H_ */
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