| 1 | /* $NetBSD: pfil.c,v 1.28 2013/06/29 21:06:58 rmind Exp $ */ |
| 2 | |
| 3 | /* |
| 4 | * Copyright (c) 2013 Mindaugas Rasiukevicius <rmind at NetBSD org> |
| 5 | * Copyright (c) 1996 Matthew R. Green |
| 6 | * All rights reserved. |
| 7 | * |
| 8 | * Redistribution and use in source and binary forms, with or without |
| 9 | * modification, are permitted provided that the following conditions |
| 10 | * are met: |
| 11 | * 1. Redistributions of source code must retain the above copyright |
| 12 | * notice, this list of conditions and the following disclaimer. |
| 13 | * 2. Redistributions in binary form must reproduce the above copyright |
| 14 | * notice, this list of conditions and the following disclaimer in the |
| 15 | * documentation and/or other materials provided with the distribution. |
| 16 | * |
| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
| 22 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| 23 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
| 24 | * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| 25 | * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 26 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 27 | * SUCH DAMAGE. |
| 28 | */ |
| 29 | |
| 30 | #include <sys/cdefs.h> |
| 31 | __KERNEL_RCSID(0, "$NetBSD: pfil.c,v 1.28 2013/06/29 21:06:58 rmind Exp $" ); |
| 32 | |
| 33 | #include <sys/param.h> |
| 34 | #include <sys/systm.h> |
| 35 | #include <sys/queue.h> |
| 36 | #include <sys/kmem.h> |
| 37 | |
| 38 | #include <net/if.h> |
| 39 | #include <net/pfil.h> |
| 40 | |
| 41 | #define MAX_HOOKS 8 |
| 42 | |
| 43 | typedef struct { |
| 44 | pfil_func_t pfil_func; |
| 45 | void * pfil_arg; |
| 46 | } pfil_hook_t; |
| 47 | |
| 48 | typedef struct { |
| 49 | pfil_hook_t hooks[MAX_HOOKS]; |
| 50 | u_int nhooks; |
| 51 | } pfil_list_t; |
| 52 | |
| 53 | struct pfil_head { |
| 54 | pfil_list_t ph_in; |
| 55 | pfil_list_t ph_out; |
| 56 | pfil_list_t ph_ifaddr; |
| 57 | pfil_list_t ph_ifevent; |
| 58 | int ph_type; |
| 59 | void * ph_key; |
| 60 | LIST_ENTRY(pfil_head) ph_list; |
| 61 | }; |
| 62 | |
| 63 | static const int pfil_flag_cases[] = { |
| 64 | PFIL_IN, PFIL_OUT, PFIL_IFADDR, PFIL_IFNET |
| 65 | }; |
| 66 | |
| 67 | static LIST_HEAD(, pfil_head) pfil_head_list __read_mostly = |
| 68 | LIST_HEAD_INITIALIZER(&pfil_head_list); |
| 69 | |
| 70 | /* |
| 71 | * pfil_head_create: create and register a packet filter head. |
| 72 | */ |
| 73 | pfil_head_t * |
| 74 | pfil_head_create(int type, void *key) |
| 75 | { |
| 76 | pfil_head_t *ph; |
| 77 | |
| 78 | if (pfil_head_get(type, key)) { |
| 79 | return NULL; |
| 80 | } |
| 81 | ph = kmem_zalloc(sizeof(pfil_head_t), KM_SLEEP); |
| 82 | ph->ph_type = type; |
| 83 | ph->ph_key = key; |
| 84 | |
| 85 | LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list); |
| 86 | return ph; |
| 87 | } |
| 88 | |
| 89 | /* |
| 90 | * pfil_head_destroy: remove and destroy a packet filter head. |
| 91 | */ |
| 92 | void |
| 93 | pfil_head_destroy(pfil_head_t *pfh) |
| 94 | { |
| 95 | LIST_REMOVE(pfh, ph_list); |
| 96 | kmem_free(pfh, sizeof(pfil_head_t)); |
| 97 | } |
| 98 | |
| 99 | /* |
| 100 | * pfil_head_get: returns the packer filter head for a given key. |
| 101 | */ |
| 102 | pfil_head_t * |
| 103 | pfil_head_get(int type, void *key) |
| 104 | { |
| 105 | pfil_head_t *ph; |
| 106 | |
| 107 | LIST_FOREACH(ph, &pfil_head_list, ph_list) { |
| 108 | if (ph->ph_type == type && ph->ph_key == key) |
| 109 | break; |
| 110 | } |
| 111 | return ph; |
| 112 | } |
| 113 | |
| 114 | static pfil_list_t * |
| 115 | pfil_hook_get(int dir, pfil_head_t *ph) |
| 116 | { |
| 117 | switch (dir) { |
| 118 | case PFIL_IN: |
| 119 | return &ph->ph_in; |
| 120 | case PFIL_OUT: |
| 121 | return &ph->ph_out; |
| 122 | case PFIL_IFADDR: |
| 123 | return &ph->ph_ifaddr; |
| 124 | case PFIL_IFNET: |
| 125 | return &ph->ph_ifevent; |
| 126 | } |
| 127 | return NULL; |
| 128 | } |
| 129 | |
| 130 | static int |
| 131 | pfil_list_add(pfil_list_t *phlist, pfil_func_t func, void *arg, int flags) |
| 132 | { |
| 133 | const u_int nhooks = phlist->nhooks; |
| 134 | pfil_hook_t *pfh; |
| 135 | |
| 136 | /* Check if we have a free slot. */ |
| 137 | if (nhooks == MAX_HOOKS) { |
| 138 | return ENOSPC; |
| 139 | } |
| 140 | KASSERT(nhooks < MAX_HOOKS); |
| 141 | |
| 142 | /* Make sure the hook is not already added. */ |
| 143 | for (u_int i = 0; i < nhooks; i++) { |
| 144 | pfh = &phlist->hooks[i]; |
| 145 | if (pfh->pfil_func == func && pfh->pfil_arg == arg) |
| 146 | return EEXIST; |
| 147 | } |
| 148 | |
| 149 | /* |
| 150 | * Finally, add the hook. Note: for PFIL_IN we insert the hooks in |
| 151 | * reverse order of the PFIL_OUT so that the same path is followed |
| 152 | * in or out of the kernel. |
| 153 | */ |
| 154 | if (flags & PFIL_IN) { |
| 155 | /* XXX: May want to revisit this later; */ |
| 156 | size_t len = sizeof(pfil_hook_t) * nhooks; |
| 157 | pfh = &phlist->hooks[0]; |
| 158 | memmove(&phlist->hooks[1], pfh, len); |
| 159 | } else { |
| 160 | pfh = &phlist->hooks[nhooks]; |
| 161 | } |
| 162 | phlist->nhooks++; |
| 163 | |
| 164 | pfh->pfil_func = func; |
| 165 | pfh->pfil_arg = arg; |
| 166 | return 0; |
| 167 | } |
| 168 | |
| 169 | /* |
| 170 | * pfil_add_hook: add a function (hook) to the packet filter head. |
| 171 | * The possible flags are: |
| 172 | * |
| 173 | * PFIL_IN call on incoming packets |
| 174 | * PFIL_OUT call on outgoing packets |
| 175 | * PFIL_ALL call on all of the above |
| 176 | * PFIL_IFADDR call on interface reconfig (mbuf is ioctl #) |
| 177 | * PFIL_IFNET call on interface attach/detach (mbuf is PFIL_IFNET_*) |
| 178 | */ |
| 179 | int |
| 180 | pfil_add_hook(pfil_func_t func, void *arg, int flags, pfil_head_t *ph) |
| 181 | { |
| 182 | int error = 0; |
| 183 | |
| 184 | KASSERT(func != NULL); |
| 185 | |
| 186 | for (u_int i = 0; i < __arraycount(pfil_flag_cases); i++) { |
| 187 | const int fcase = pfil_flag_cases[i]; |
| 188 | pfil_list_t *phlist; |
| 189 | |
| 190 | if ((flags & fcase) == 0) { |
| 191 | continue; |
| 192 | } |
| 193 | phlist = pfil_hook_get(fcase, ph); |
| 194 | if ((error = pfil_list_add(phlist, func, arg, flags)) != 0) { |
| 195 | break; |
| 196 | } |
| 197 | } |
| 198 | if (error) { |
| 199 | pfil_remove_hook(func, arg, flags, ph); |
| 200 | } |
| 201 | return error; |
| 202 | } |
| 203 | |
| 204 | /* |
| 205 | * pfil_list_remove: remove the hook from a specified list. |
| 206 | */ |
| 207 | static int |
| 208 | pfil_list_remove(pfil_list_t *phlist, pfil_func_t func, void *arg) |
| 209 | { |
| 210 | const u_int nhooks = phlist->nhooks; |
| 211 | |
| 212 | for (u_int i = 0; i < nhooks; i++) { |
| 213 | pfil_hook_t *last, *pfh = &phlist->hooks[i]; |
| 214 | |
| 215 | if (pfh->pfil_func != func || pfh->pfil_arg != arg) { |
| 216 | continue; |
| 217 | } |
| 218 | if ((last = &phlist->hooks[nhooks - 1]) != pfh) { |
| 219 | memcpy(pfh, last, sizeof(pfil_hook_t)); |
| 220 | } |
| 221 | phlist->nhooks--; |
| 222 | return 0; |
| 223 | } |
| 224 | return ENOENT; |
| 225 | } |
| 226 | |
| 227 | /* |
| 228 | * pfil_remove_hook: remove the hook from the packet filter head. |
| 229 | */ |
| 230 | int |
| 231 | pfil_remove_hook(pfil_func_t func, void *arg, int flags, pfil_head_t *ph) |
| 232 | { |
| 233 | for (u_int i = 0; i < __arraycount(pfil_flag_cases); i++) { |
| 234 | const int fcase = pfil_flag_cases[i]; |
| 235 | pfil_list_t *pflist; |
| 236 | |
| 237 | if ((flags & fcase) == 0) { |
| 238 | continue; |
| 239 | } |
| 240 | pflist = pfil_hook_get(fcase, ph); |
| 241 | (void)pfil_list_remove(pflist, func, arg); |
| 242 | } |
| 243 | return 0; |
| 244 | } |
| 245 | |
| 246 | /* |
| 247 | * pfil_run_hooks: run the specified packet filter hooks. |
| 248 | */ |
| 249 | int |
| 250 | pfil_run_hooks(pfil_head_t *ph, struct mbuf **mp, ifnet_t *ifp, int dir) |
| 251 | { |
| 252 | const bool pass_mbuf = (dir & PFIL_ALL) != 0 && mp; |
| 253 | struct mbuf *m = pass_mbuf ? *mp : NULL; |
| 254 | pfil_list_t *phlist; |
| 255 | int ret = 0; |
| 256 | |
| 257 | if ((phlist = pfil_hook_get(dir, ph)) == NULL) { |
| 258 | return ret; |
| 259 | } |
| 260 | |
| 261 | for (u_int i = 0; i < phlist->nhooks; i++) { |
| 262 | pfil_hook_t *pfh = &phlist->hooks[i]; |
| 263 | pfil_func_t func = pfh->pfil_func; |
| 264 | |
| 265 | if (__predict_true(dir & PFIL_ALL)) { |
| 266 | ret = (*func)(pfh->pfil_arg, &m, ifp, dir); |
| 267 | if (m == NULL) |
| 268 | break; |
| 269 | } else { |
| 270 | ret = (*func)(pfh->pfil_arg, mp, ifp, dir); |
| 271 | } |
| 272 | if (ret) |
| 273 | break; |
| 274 | } |
| 275 | |
| 276 | if (pass_mbuf) { |
| 277 | *mp = m; |
| 278 | } |
| 279 | return ret; |
| 280 | } |
| 281 | |