1 /* $NetBSD: npf_handler.c,v 1.21 2012/08/12 03:35:14 rmind Exp $ */ 2 3 /*- 4 * Copyright (c) 2009-2012 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This material is based upon work partially supported by The 8 * NetBSD Foundation under a contract with Mindaugas Rasiukevicius. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /* 33 * NPF packet handler. 34 */ 35 36 #include <sys/cdefs.h> 37 __KERNEL_RCSID(0, "$NetBSD: npf_handler.c,v 1.21 2012/08/12 03:35:14 rmind Exp $"); 38 39 #include <sys/types.h> 40 #include <sys/param.h> 41 42 #include <sys/mbuf.h> 43 #include <sys/mutex.h> 44 #include <net/if.h> 45 #include <net/pfil.h> 46 #include <sys/socketvar.h> 47 48 #include <netinet/in_systm.h> 49 #include <netinet/in.h> 50 #include <netinet/ip_var.h> 51 #include <netinet/ip6.h> 52 #include <netinet6/ip6_var.h> 53 54 #include "npf_impl.h" 55 56 /* 57 * If npf_ph_if != NULL, pfil hooks are registered. If NULL, not registered. 58 * Used to check the state. Locked by: softnet_lock + KERNEL_LOCK (XXX). 59 */ 60 static struct pfil_head * npf_ph_if = NULL; 61 static struct pfil_head * npf_ph_inet = NULL; 62 static struct pfil_head * npf_ph_inet6 = NULL; 63 64 /* 65 * npf_ifhook: hook handling interface changes. 66 */ 67 static int 68 npf_ifhook(void *arg, struct mbuf **mp, ifnet_t *ifp, int di) 69 { 70 71 return 0; 72 } 73 74 /* 75 * npf_packet_handler: main packet handling routine for layer 3. 76 * 77 * Note: packet flow and inspection logic is in strict order. 78 */ 79 int 80 npf_packet_handler(void *arg, struct mbuf **mp, ifnet_t *ifp, int di) 81 { 82 nbuf_t *nbuf = *mp; 83 npf_cache_t npc; 84 npf_session_t *se; 85 npf_ruleset_t *rlset; 86 npf_rule_t *rl; 87 npf_rproc_t *rp; 88 int error, retfl; 89 int decision; 90 91 /* 92 * Initialise packet information cache. 93 * Note: it is enough to clear the info bits. 94 */ 95 npc.npc_info = 0; 96 decision = NPF_DECISION_BLOCK; 97 error = 0; 98 retfl = 0; 99 rp = NULL; 100 101 /* Cache everything. Determine whether it is an IP fragment. */ 102 if (npf_cache_all(&npc, nbuf) & NPC_IPFRAG) { 103 /* 104 * Pass to IPv4 or IPv6 reassembly mechanism. 105 */ 106 error = EINVAL; 107 108 if (npf_iscached(&npc, NPC_IP4)) { 109 struct ip *ip = nbuf_dataptr(*mp); 110 error = ip_reass_packet(mp, ip); 111 } else if (npf_iscached(&npc, NPC_IP6)) { 112 #ifdef INET6 113 /* 114 * Note: ip6_reass_packet() offset is the start of 115 * the fragment header. 116 */ 117 const u_int hlen = npf_cache_hlen(&npc); 118 error = ip6_reass_packet(mp, hlen); 119 #endif 120 } 121 if (error) { 122 npf_stats_inc(NPF_STAT_REASSFAIL); 123 se = NULL; 124 goto out; 125 } 126 if (*mp == NULL) { 127 /* More fragments should come; return. */ 128 npf_stats_inc(NPF_STAT_FRAGMENTS); 129 return 0; 130 } 131 132 /* 133 * Reassembly is complete, we have the final packet. 134 * Cache again, since layer 4 data is accessible now. 135 */ 136 nbuf = (nbuf_t *)*mp; 137 npc.npc_info = 0; 138 139 int ret __unused = npf_cache_all(&npc, nbuf); 140 KASSERT((ret & NPC_IPFRAG) == 0); 141 npf_stats_inc(NPF_STAT_REASSEMBLY); 142 } 143 144 /* Inspect the list of sessions. */ 145 se = npf_session_inspect(&npc, nbuf, ifp, di, &error); 146 147 /* If "passing" session found - skip the ruleset inspection. */ 148 if (se && npf_session_pass(se, &rp)) { 149 npf_stats_inc(NPF_STAT_PASS_SESSION); 150 KASSERT(error == 0); 151 goto pass; 152 } 153 if (error) { 154 goto block; 155 } 156 157 /* Acquire the lock, inspect the ruleset using this packet. */ 158 npf_core_enter(); 159 rlset = npf_core_ruleset(); 160 rl = npf_ruleset_inspect(&npc, nbuf, rlset, ifp, di, NPF_LAYER_3); 161 if (rl == NULL) { 162 bool default_pass = npf_default_pass(); 163 npf_core_exit(); 164 165 if (default_pass) { 166 npf_stats_inc(NPF_STAT_PASS_DEFAULT); 167 goto pass; 168 } 169 npf_stats_inc(NPF_STAT_BLOCK_DEFAULT); 170 goto block; 171 } 172 173 /* 174 * Get the rule procedure (acquires a reference) for assocation 175 * with a session (if any) and execution. 176 */ 177 KASSERT(rp == NULL); 178 rp = npf_rule_getrproc(rl); 179 180 /* Apply the rule, release the lock. */ 181 error = npf_rule_apply(&npc, nbuf, rl, &retfl); 182 if (error) { 183 npf_stats_inc(NPF_STAT_BLOCK_RULESET); 184 goto block; 185 } 186 npf_stats_inc(NPF_STAT_PASS_RULESET); 187 188 /* 189 * Establish a "pass" session, if required. Just proceed, if session 190 * creation fails (e.g. due to unsupported protocol). 191 * 192 * Note: the reference on the rule procedure is transfered to the 193 * session. It will be released on session destruction. 194 */ 195 if ((retfl & NPF_RULE_STATEFUL) != 0 && !se) { 196 se = npf_session_establish(&npc, nbuf, ifp, di); 197 if (se) { 198 npf_session_setpass(se, rp); 199 } 200 } 201 pass: 202 decision = NPF_DECISION_PASS; 203 KASSERT(error == 0); 204 /* 205 * Perform NAT. 206 */ 207 error = npf_do_nat(&npc, se, nbuf, ifp, di); 208 block: 209 /* 210 * Execute rule procedure, if any. 211 */ 212 if (rp) { 213 npf_rproc_run(&npc, nbuf, rp, error); 214 } 215 out: 216 /* 217 * Release the reference on a session. Release the reference on a 218 * rule procedure only if there was no association. 219 */ 220 if (se) { 221 npf_session_release(se); 222 } else if (rp) { 223 npf_rproc_release(rp); 224 } 225 226 /* Pass the packet if decided and there is no error. */ 227 if (decision == NPF_DECISION_PASS && !error) { 228 /* 229 * XXX: Disable for now, it will be set accordingly later, 230 * for optimisations (to reduce inspection). 231 */ 232 (*mp)->m_flags &= ~M_CANFASTFWD; 233 return 0; 234 } 235 236 /* 237 * Block the packet. ENETUNREACH is used to indicate blocking. 238 * Depending on the flags and protocol, return TCP reset (RST) or 239 * ICMP destination unreachable. 240 */ 241 if (retfl && npf_return_block(&npc, nbuf, retfl)) { 242 *mp = NULL; 243 } 244 245 if (!error) { 246 error = ENETUNREACH; 247 } 248 249 if (*mp) { 250 m_freem(*mp); 251 *mp = NULL; 252 } 253 return error; 254 } 255 256 /* 257 * npf_pfil_register: register pfil(9) hooks. 258 */ 259 int 260 npf_pfil_register(void) 261 { 262 int error; 263 264 mutex_enter(softnet_lock); 265 KERNEL_LOCK(1, NULL); 266 267 /* Check if pfil hooks are not already registered. */ 268 if (npf_ph_if) { 269 error = EEXIST; 270 goto fail; 271 } 272 273 /* Capture point of any activity in interfaces and IP layer. */ 274 npf_ph_if = pfil_head_get(PFIL_TYPE_IFNET, 0); 275 npf_ph_inet = pfil_head_get(PFIL_TYPE_AF, AF_INET); 276 npf_ph_inet6 = pfil_head_get(PFIL_TYPE_AF, AF_INET6); 277 if (!npf_ph_if || (!npf_ph_inet && !npf_ph_inet6)) { 278 npf_ph_if = NULL; 279 error = ENOENT; 280 goto fail; 281 } 282 283 /* Interface re-config or attach/detach hook. */ 284 error = pfil_add_hook(npf_ifhook, NULL, 285 PFIL_WAITOK | PFIL_IFADDR | PFIL_IFNET, npf_ph_if); 286 KASSERT(error == 0); 287 288 /* Packet IN/OUT handler on all interfaces and IP layer. */ 289 if (npf_ph_inet) { 290 error = pfil_add_hook(npf_packet_handler, NULL, 291 PFIL_WAITOK | PFIL_ALL, npf_ph_inet); 292 KASSERT(error == 0); 293 } 294 if (npf_ph_inet6) { 295 error = pfil_add_hook(npf_packet_handler, NULL, 296 PFIL_WAITOK | PFIL_ALL, npf_ph_inet6); 297 KASSERT(error == 0); 298 } 299 fail: 300 KERNEL_UNLOCK_ONE(NULL); 301 mutex_exit(softnet_lock); 302 303 return error; 304 } 305 306 /* 307 * npf_pfil_unregister: unregister pfil(9) hooks. 308 */ 309 void 310 npf_pfil_unregister(void) 311 { 312 313 mutex_enter(softnet_lock); 314 KERNEL_LOCK(1, NULL); 315 316 if (npf_ph_if) { 317 (void)pfil_remove_hook(npf_ifhook, NULL, 318 PFIL_IFADDR | PFIL_IFNET, npf_ph_if); 319 } 320 if (npf_ph_inet) { 321 (void)pfil_remove_hook(npf_packet_handler, NULL, 322 PFIL_ALL, npf_ph_inet); 323 } 324 if (npf_ph_inet6) { 325 (void)pfil_remove_hook(npf_packet_handler, NULL, 326 PFIL_ALL, npf_ph_inet6); 327 } 328 329 npf_ph_if = NULL; 330 331 KERNEL_UNLOCK_ONE(NULL); 332 mutex_exit(softnet_lock); 333 } 334 335 bool 336 npf_pfil_registered_p(void) 337 { 338 return npf_ph_if != NULL; 339 } 340