1 /* $NetBSD: npf_handler.c,v 1.10 2011/11/06 02:49:03 rmind Exp $ */ 2 3 /*- 4 * Copyright (c) 2009-2010 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 1.10 2011/11/06 02:49:03 rmind Exp $"); 38 39 #include <sys/param.h> 40 #include <sys/systm.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 registers. 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 static bool default_pass = true; 65 66 int npf_packet_handler(void *, struct mbuf **, ifnet_t *, int); 67 68 /* 69 * npf_ifhook: hook handling interface changes. 70 */ 71 static int 72 npf_ifhook(void *arg, struct mbuf **mp, ifnet_t *ifp, int di) 73 { 74 75 return 0; 76 } 77 78 /* 79 * npf_packet_handler: main packet handling routine for layer 3. 80 * 81 * Note: packet flow and inspection logic is in strict order. 82 */ 83 int 84 npf_packet_handler(void *arg, struct mbuf **mp, ifnet_t *ifp, int di) 85 { 86 nbuf_t *nbuf = *mp; 87 npf_cache_t npc; 88 npf_session_t *se; 89 npf_ruleset_t *rlset; 90 npf_rule_t *rl; 91 npf_rproc_t *rp; 92 int retfl, error, ret; 93 94 /* 95 * Initialise packet information cache. 96 * Note: it is enough to clear the info bits. 97 */ 98 npc.npc_info = 0; 99 error = 0; 100 retfl = 0; 101 rp = NULL; 102 ret = 0; 103 104 /* Cache everything. Determine whether it is an IP fragment. */ 105 npf_cache_all(&npc, nbuf); 106 107 if (npf_iscached(&npc, NPC_IPFRAG)) { 108 /* Pass to IPv4 or IPv6 reassembly mechanism. */ 109 if (npf_iscached(&npc, NPC_IP4)) { 110 struct ip *ip = nbuf_dataptr(*mp); 111 ret = ip_reass_packet(mp, ip); 112 } else { 113 KASSERT(npf_iscached(&npc, NPC_IP6)); 114 #ifdef INET6 115 /* 116 * Note: frag6_input() offset is the start of the 117 * fragment header. 118 */ 119 size_t hlen = npf_cache_hlen(&npc, nbuf); 120 ret = ip6_reass_packet(mp, hlen); 121 #else 122 ret = -1; 123 #endif 124 } 125 126 if (ret) { 127 error = EINVAL; 128 se = NULL; 129 goto out; 130 } 131 if (*mp == NULL) { 132 /* More fragments should come; return. */ 133 return 0; 134 } 135 136 /* 137 * Reassembly is complete, we have the final packet. 138 * Cache again, since layer 3 daya is accessible now. 139 */ 140 nbuf = (nbuf_t *)*mp; 141 npc.npc_info = 0; 142 npf_cache_all(&npc, nbuf); 143 } 144 145 /* Inspect the list of sessions. */ 146 se = npf_session_inspect(&npc, nbuf, di); 147 148 /* If "passing" session found - skip the ruleset inspection. */ 149 if (se && npf_session_pass(se, &rp)) { 150 npf_stats_inc(NPF_STAT_PASS_SESSION); 151 goto pass; 152 } 153 154 /* Acquire the lock, inspect the ruleset using this packet. */ 155 npf_core_enter(); 156 rlset = npf_core_ruleset(); 157 rl = npf_ruleset_inspect(&npc, nbuf, rlset, ifp, di, NPF_LAYER_3); 158 if (rl == NULL) { 159 if (default_pass) { 160 npf_stats_inc(NPF_STAT_PASS_DEFAULT); 161 goto pass; 162 } 163 npf_stats_inc(NPF_STAT_BLOCK_DEFAULT); 164 error = ENETUNREACH; 165 goto block; 166 } 167 168 /* Get rule procedure for assocation and/or execution. */ 169 KASSERT(rp == NULL); 170 rp = npf_rproc_return(rl); 171 172 /* Apply the rule, release the lock. */ 173 error = npf_rule_apply(&npc, nbuf, rl, &retfl); 174 if (error) { 175 npf_stats_inc(NPF_STAT_BLOCK_RULESET); 176 goto block; 177 } 178 npf_stats_inc(NPF_STAT_PASS_RULESET); 179 180 /* Establish a "pass" session, if required. */ 181 if ((retfl & NPF_RULE_KEEPSTATE) != 0 && !se) { 182 se = npf_session_establish(&npc, nbuf, di); 183 if (se == NULL) { 184 error = ENOMEM; 185 goto out; 186 } 187 npf_session_setpass(se, rp); 188 } 189 pass: 190 KASSERT(error == 0); 191 /* 192 * Perform NAT. 193 */ 194 error = npf_do_nat(&npc, se, nbuf, ifp, di); 195 block: 196 /* 197 * Perform rule procedure, if any. 198 */ 199 if (rp) { 200 npf_rproc_run(&npc, nbuf, rp, error); 201 } 202 out: 203 /* Release the reference on session, or rule procedure. */ 204 if (se) { 205 npf_session_release(se); 206 } else if (rp) { 207 npf_rproc_release(rp); /* XXXkmem */ 208 } 209 210 /* 211 * If error is set - drop the packet. 212 * Normally, ENETUNREACH is used for "block". 213 */ 214 if (error) { 215 /* 216 * Depending on flags and protocol, return TCP reset (RST) 217 * or ICMP destination unreachable 218 */ 219 if (retfl) { 220 npf_return_block(&npc, nbuf, retfl); 221 } 222 if (error != ENETUNREACH) { 223 NPF_PRINTF(("NPF: error in handler '%d'\n", error)); 224 npf_stats_inc(NPF_STAT_ERROR); 225 } 226 m_freem(*mp); 227 *mp = NULL; 228 } else { 229 /* 230 * XXX: Disable for now, it will be set accordingly later, 231 * for optimisations (to reduce inspection). 232 */ 233 (*mp)->m_flags &= ~M_CANFASTFWD; 234 } 235 return error; 236 } 237 238 /* 239 * npf_register_pfil: register pfil(9) hooks. 240 */ 241 int 242 npf_register_pfil(void) 243 { 244 int error; 245 246 mutex_enter(softnet_lock); 247 KERNEL_LOCK(1, NULL); 248 249 /* Check if pfil hooks are not already registered. */ 250 if (npf_ph_if) { 251 error = EEXIST; 252 goto fail; 253 } 254 255 /* Capture point of any activity in interfaces and IP layer. */ 256 npf_ph_if = pfil_head_get(PFIL_TYPE_IFNET, 0); 257 npf_ph_inet = pfil_head_get(PFIL_TYPE_AF, AF_INET); 258 npf_ph_inet6 = pfil_head_get(PFIL_TYPE_AF, AF_INET6); 259 if (npf_ph_if == NULL || npf_ph_inet == NULL) { 260 npf_ph_if = NULL; 261 error = ENOENT; 262 goto fail; 263 } 264 265 /* Interface re-config or attach/detach hook. */ 266 error = pfil_add_hook(npf_ifhook, NULL, 267 PFIL_WAITOK | PFIL_IFADDR | PFIL_IFNET, npf_ph_if); 268 KASSERT(error == 0); 269 270 /* Packet IN/OUT handler on all interfaces and IP layer. */ 271 error = pfil_add_hook(npf_packet_handler, NULL, 272 PFIL_WAITOK | PFIL_ALL, npf_ph_inet); 273 KASSERT(error == 0); 274 275 error = pfil_add_hook(npf_packet_handler, NULL, 276 PFIL_WAITOK | PFIL_ALL, npf_ph_inet6); 277 KASSERT(error == 0); 278 fail: 279 KERNEL_UNLOCK_ONE(NULL); 280 mutex_exit(softnet_lock); 281 282 return error; 283 } 284 285 /* 286 * npf_unregister: unregister pfil(9) hooks. 287 */ 288 void 289 npf_unregister_pfil(void) 290 { 291 292 mutex_enter(softnet_lock); 293 KERNEL_LOCK(1, NULL); 294 295 if (npf_ph_if) { 296 (void)pfil_remove_hook(npf_packet_handler, NULL, 297 PFIL_ALL, npf_ph_inet6); 298 (void)pfil_remove_hook(npf_packet_handler, NULL, 299 PFIL_ALL, npf_ph_inet); 300 (void)pfil_remove_hook(npf_ifhook, NULL, 301 PFIL_IFADDR | PFIL_IFNET, npf_ph_if); 302 303 npf_ph_if = NULL; 304 } 305 306 KERNEL_UNLOCK_ONE(NULL); 307 mutex_exit(softnet_lock); 308 } 309