1/* $NetBSD: if_l2tp.h,v 1.6 2018/10/19 00:12:56 knakahara Exp $ */
2
3/*
4 * Copyright (c) 2017 Internet Initiative Japan Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29/*
30 * L2TPv3 kernel interface
31 */
32
33#ifndef _NET_IF_L2TP_H_
34#define _NET_IF_L2TP_H_
35
36#include <sys/queue.h>
37#include <sys/ioccom.h>
38#ifdef _KERNEL
39#include <sys/pserialize.h>
40#include <sys/psref.h>
41#include <sys/pslist.h>
42#endif
43
44#include <net/if_ether.h>
45#include <netinet/in.h>
46
47#define SIOCSL2TPSESSION _IOW('i', 151, struct l2tp_req)
48#define SIOCDL2TPSESSION _IOW('i', 152, struct l2tp_req)
49#define SIOCSL2TPCOOKIE _IOW('i', 153, struct l2tp_req)
50#define SIOCDL2TPCOOKIE _IOW('i', 154, struct l2tp_req)
51#define SIOCSL2TPSTATE _IOW('i', 155, struct l2tp_req)
52#define SIOCGL2TP SIOCGIFGENERIC
53
54struct l2tp_req {
55 int state;
56 u_int my_cookie_len;
57 u_int peer_cookie_len;
58 uint32_t my_sess_id;
59 uint32_t peer_sess_id;
60 uint64_t my_cookie;
61 uint64_t peer_cookie;
62};
63
64#define L2TP_STATE_UP 1
65#define L2TP_STATE_DOWN 0
66
67#define L2TP_COOKIE_ON 1
68#define L2TP_COOKIE_OFF 0
69
70#ifdef _KERNEL
71extern struct psref_class *lv_psref_class;
72
73struct l2tp_variant {
74 struct l2tp_softc *lv_softc;
75
76 struct sockaddr *lv_psrc; /* Physical src addr */
77 struct sockaddr *lv_pdst; /* Physical dst addr */
78 const struct encaptab *lv_encap_cookie;
79
80 /* L2TP session info */
81 int lv_state;
82 uint32_t lv_my_sess_id; /* my session ID */
83 uint32_t lv_peer_sess_id; /* peer session ID */
84
85 int lv_use_cookie;
86 u_int lv_my_cookie_len;
87 u_int lv_peer_cookie_len;
88 uint64_t lv_my_cookie; /* my cookie */
89 uint64_t lv_peer_cookie; /* peer cookie */
90
91 struct psref_target lv_psref;
92};
93
94struct l2tp_ro {
95 struct route lr_ro;
96 kmutex_t *lr_lock;
97};
98
99struct l2tp_softc {
100 struct ethercom l2tp_ec; /* common area - must be at the top */
101 /* to use ether_input(), we must have this */
102 percpu_t *l2tp_ro_percpu; /* struct l2tp_ro */
103 struct l2tp_variant *l2tp_var; /*
104 * reader must use l2tp_getref_variant()
105 * instead of direct dereference.
106 */
107 kmutex_t l2tp_lock; /* writer lock for l2tp_var */
108 pserialize_t l2tp_psz;
109
110 LIST_ENTRY(l2tp_softc) l2tp_list; /* list of all l2tps */
111 struct pslist_entry l2tp_hash; /* hashed list to lookup by session id */
112};
113
114#define L2TP_ROUTE_TTL 10
115
116#define L2TP_MTU (1280) /* Default MTU */
117#define L2TP_MTU_MIN (1280) /* Minimum MTU */
118#define L2TP_MTU_MAX (8192) /* Maximum MTU */
119
120/*
121 * Get l2tp_variant from l2tp_softc.
122 *
123 * l2tp_variant itself is protected not to be freed by lv_psref.
124 * In contrast, sc->sc_var can be changed to NULL even if reader critical
125 * section. see l2tp_variant_update().
126 * So, once a reader dereference sc->sc_var by this API, the reader must not
127 * re-dereference form sc->sc_var.
128 */
129static __inline struct l2tp_variant *
130l2tp_getref_variant(struct l2tp_softc *sc, struct psref *psref)
131{
132 struct l2tp_variant *var;
133 int s;
134
135 s = pserialize_read_enter();
136 var = sc->l2tp_var;
137 if (var == NULL) {
138 pserialize_read_exit(s);
139 return NULL;
140 }
141 membar_datadep_consumer();
142 psref_acquire(psref, &var->lv_psref, lv_psref_class);
143 pserialize_read_exit(s);
144
145 return var;
146}
147
148static __inline void
149l2tp_putref_variant(struct l2tp_variant *var, struct psref *psref)
150{
151
152 if (var == NULL)
153 return;
154 psref_release(psref, &var->lv_psref, lv_psref_class);
155}
156
157static __inline bool
158l2tp_heldref_variant(struct l2tp_variant *var)
159{
160
161 return psref_held(&var->lv_psref, lv_psref_class);
162}
163
164
165/* Prototypes */
166void l2tpattach(int);
167int l2tpattach0(struct l2tp_softc *);
168void l2tp_input(struct mbuf *, struct ifnet *);
169int l2tp_ioctl(struct ifnet *, u_long, void *);
170
171struct l2tp_variant *l2tp_lookup_session_ref(uint32_t, struct psref *);
172int l2tp_check_nesting(struct ifnet *, struct mbuf *);
173
174/* TODO IP_TCPMSS support */
175#ifdef IP_TCPMSS
176struct mbuf *l2tp_tcpmss_clamp(struct ifnet *, struct mbuf *);
177#endif /* IP_TCPMSS */
178#endif /* _KERNEL */
179
180/*
181 * Locking notes:
182 * + l2tp_softc_list is protected by l2tp_list_lock (an adaptive mutex)
183 * l2tp_softc_list is list of all l2tp_softcs, and it is used to avoid
184 * unload while busy.
185 * + l2tp_hashed_list is protected by
186 * - l2tp_hash_lock (an adaptive mutex) for writer
187 * - pserialize for reader
188 * l2tp_hashed_list is hashed list of all l2tp_softcs, and it is used by
189 * input processing to find appropriate softc.
190 * + l2tp_softc->l2tp_var is protected by
191 * - l2tp_softc->l2tp_lock (an adaptive mutex) for writer
192 * - l2tp_var->lv_psref for reader
193 * l2tp_softc->l2tp_var is used for variant values while the l2tp tunnel
194 * exists.
195 * + struct l2tp_ro->lr_ro is protected by struct l2tp_ro->lr_lock.
196 * This lock is required to exclude softnet/0 lwp(such as output
197 * processing softint) and processing lwp(such as DAD timer processing).
198 *
199 * Locking order:
200 * - encap_lock => struct l2tp_softc->l2tp_lock
201 * Other mutexes must not hold simultaneously.
202 *
203 * NOTICE
204 * - l2tp_softc must not have a variant value while the l2tp tunnel exists.
205 * Such variant values must be in l2tp_softc->l2tp_var.
206 * - l2tp_softc->l2tp_var is modified like read-copy-update.
207 * So, once we dereference l2tp_softc->l2tp_var, we must
208 * keep the pointer during the same context. If we re-derefence
209 * l2tp_softc->l2tp_var, the l2tp_var may be other one because of
210 * concurrent writer processing.
211 */
212#endif /* _NET_IF_L2TP_H_ */
213