| 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 | |