1 | /* $NetBSD: bpf_stub.c,v 1.6 2012/01/30 23:31:27 matt Exp $ */ |
2 | |
3 | /* |
4 | * Copyright (c) 2010 The NetBSD Foundation, 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 | #include <sys/cdefs.h> |
30 | __KERNEL_RCSID(0, "$NetBSD: bpf_stub.c,v 1.6 2012/01/30 23:31:27 matt Exp $" ); |
31 | |
32 | #include <sys/param.h> |
33 | #include <sys/kmem.h> |
34 | #include <sys/mbuf.h> |
35 | |
36 | #include <net/bpf.h> |
37 | |
38 | struct laglist { |
39 | struct ifnet *lag_ifp; |
40 | u_int lag_dlt; |
41 | u_int lag_hlen; |
42 | struct bpf_if **lag_drvp; |
43 | |
44 | TAILQ_ENTRY(laglist) lag_entries; |
45 | }; |
46 | |
47 | static TAILQ_HEAD(, laglist) lagdrvs = TAILQ_HEAD_INITIALIZER(lagdrvs); |
48 | |
49 | static void bpf_stub_attach(struct ifnet *, u_int, u_int, struct bpf_if **); |
50 | static void bpf_stub_detach(struct ifnet *); |
51 | |
52 | static void bpf_stub_null(void); |
53 | static void bpf_stub_warn(void); |
54 | |
55 | static kmutex_t handovermtx; |
56 | static kcondvar_t handovercv; |
57 | static bool handover; |
58 | |
59 | struct bpf_ops bpf_ops_stub = { |
60 | .bpf_attach = bpf_stub_attach, |
61 | .bpf_detach = bpf_stub_detach, |
62 | .bpf_change_type = (void *)bpf_stub_null, |
63 | |
64 | .bpf_tap = (void *)bpf_stub_warn, |
65 | .bpf_mtap = (void *)bpf_stub_warn, |
66 | .bpf_mtap2 = (void *)bpf_stub_warn, |
67 | .bpf_mtap_af = (void *)bpf_stub_warn, |
68 | .bpf_mtap_sl_in = (void *)bpf_stub_warn, |
69 | .bpf_mtap_sl_out = (void *)bpf_stub_warn, |
70 | }; |
71 | struct bpf_ops *bpf_ops; |
72 | |
73 | static void |
74 | bpf_stub_attach(struct ifnet *ifp, u_int dlt, u_int hlen, struct bpf_if **drvp) |
75 | { |
76 | struct laglist *lag; |
77 | bool storeattach = true; |
78 | |
79 | lag = kmem_alloc(sizeof(*lag), KM_SLEEP); |
80 | lag->lag_ifp = ifp; |
81 | lag->lag_dlt = dlt; |
82 | lag->lag_hlen = hlen; |
83 | lag->lag_drvp = drvp; |
84 | |
85 | mutex_enter(&handovermtx); |
86 | /* |
87 | * If handover is in progress, wait for it to finish and complete |
88 | * attach after that. Otherwise record ourselves. |
89 | */ |
90 | while (handover) { |
91 | storeattach = false; |
92 | cv_wait(&handovercv, &handovermtx); |
93 | } |
94 | |
95 | if (storeattach == false) { |
96 | mutex_exit(&handovermtx); |
97 | kmem_free(lag, sizeof(*lag)); |
98 | KASSERT(bpf_ops != &bpf_ops_stub); /* revisit when unloadable */ |
99 | bpf_ops->bpf_attach(ifp, dlt, hlen, drvp); |
100 | } else { |
101 | *drvp = NULL; |
102 | TAILQ_INSERT_TAIL(&lagdrvs, lag, lag_entries); |
103 | mutex_exit(&handovermtx); |
104 | } |
105 | } |
106 | |
107 | static void |
108 | bpf_stub_detach(struct ifnet *ifp) |
109 | { |
110 | TAILQ_HEAD(, laglist) rmlist; |
111 | struct laglist *lag, *lag_next; |
112 | bool didhand; |
113 | |
114 | TAILQ_INIT(&rmlist); |
115 | |
116 | didhand = false; |
117 | mutex_enter(&handovermtx); |
118 | while (handover) { |
119 | didhand = true; |
120 | cv_wait(&handovercv, &handovermtx); |
121 | } |
122 | |
123 | if (didhand == false) { |
124 | /* atomically remove all */ |
125 | for (lag = TAILQ_FIRST(&lagdrvs); lag; lag = lag_next) { |
126 | lag_next = TAILQ_NEXT(lag, lag_entries); |
127 | if (lag->lag_ifp == ifp) { |
128 | TAILQ_REMOVE(&lagdrvs, lag, lag_entries); |
129 | TAILQ_INSERT_HEAD(&rmlist, lag, lag_entries); |
130 | } |
131 | } |
132 | mutex_exit(&handovermtx); |
133 | while ((lag = TAILQ_FIRST(&rmlist)) != NULL) { |
134 | TAILQ_REMOVE(&rmlist, lag, lag_entries); |
135 | kmem_free(lag, sizeof(*lag)); |
136 | } |
137 | } else { |
138 | mutex_exit(&handovermtx); |
139 | KASSERT(bpf_ops != &bpf_ops_stub); /* revisit when unloadable */ |
140 | bpf_ops->bpf_detach(ifp); |
141 | } |
142 | } |
143 | |
144 | static void |
145 | bpf_stub_null(void) |
146 | { |
147 | |
148 | } |
149 | |
150 | static void |
151 | bpf_stub_warn(void) |
152 | { |
153 | |
154 | #ifdef DEBUG |
155 | panic("bpf method called without attached bpf_if" ); |
156 | #endif |
157 | #ifdef DIAGNOSTIC |
158 | printf("bpf method called without attached bpf_if\n" ); |
159 | #endif |
160 | } |
161 | |
162 | void |
163 | bpf_setops(void) |
164 | { |
165 | |
166 | mutex_init(&handovermtx, MUTEX_DEFAULT, IPL_NONE); |
167 | cv_init(&handovercv, "bpfops" ); |
168 | bpf_ops = &bpf_ops_stub; |
169 | } |
170 | |
171 | /* |
172 | * Party's over, prepare for handover. |
173 | * It needs to happen *before* bpf_ops is set to make it atomic |
174 | * to callers (see also stub implementations, which wait if |
175 | * called during handover). The likelyhood of seeing a full |
176 | * attach-detach *during* handover comes close to astronomical, |
177 | * but handle it anyway since it's relatively easy. |
178 | */ |
179 | void |
180 | bpf_ops_handover_enter(struct bpf_ops *newops) |
181 | { |
182 | struct laglist *lag; |
183 | |
184 | mutex_enter(&handovermtx); |
185 | handover = true; |
186 | |
187 | while ((lag = TAILQ_FIRST(&lagdrvs)) != NULL) { |
188 | TAILQ_REMOVE(&lagdrvs, lag, lag_entries); |
189 | mutex_exit(&handovermtx); |
190 | newops->bpf_attach(lag->lag_ifp, lag->lag_dlt, |
191 | lag->lag_hlen, lag->lag_drvp); |
192 | kmem_free(lag, sizeof(*lag)); |
193 | mutex_enter(&handovermtx); |
194 | } |
195 | mutex_exit(&handovermtx); |
196 | } |
197 | |
198 | /* hangover done */ |
199 | void |
200 | bpf_ops_handover_exit(void) |
201 | { |
202 | |
203 | mutex_enter(&handovermtx); |
204 | handover = false; |
205 | cv_broadcast(&handovercv); |
206 | mutex_exit(&handovermtx); |
207 | } |
208 | |