1 /* $NetBSD: npf_handler.c,v 1.36 2017/01/29 00:15:54 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2009-2013 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 * Note: pfil(9) hooks are currently locked by softnet_lock and kernel-lock. 36 */ 37 38 #ifdef _KERNEL 39 #include <sys/cdefs.h> 40 __KERNEL_RCSID(0, "$NetBSD: npf_handler.c,v 1.36 2017/01/29 00:15:54 christos Exp $"); 41 42 #include <sys/types.h> 43 #include <sys/param.h> 44 45 #include <sys/mbuf.h> 46 #include <sys/mutex.h> 47 #include <net/if.h> 48 #include <net/pfil.h> 49 #include <sys/socketvar.h> 50 51 #include <netinet/in_systm.h> 52 #include <netinet/in.h> 53 #include <netinet/ip_var.h> 54 #include <netinet/ip6.h> 55 #include <netinet6/ip6_var.h> 56 #endif 57 58 #include "npf_impl.h" 59 #include "npf_conn.h" 60 61 #if defined(_NPF_STANDALONE) 62 #define m_freem(m) npf->mbufops->free(m) 63 #define m_clear_flag(m,f) 64 #else 65 #define m_clear_flag(m,f) (m)->m_flags &= ~(f) 66 #endif 67 68 #ifndef INET6 69 #define ip6_reass_packet(x, y) ENOTSUP 70 #endif 71 72 static int 73 npf_reassembly(npf_t *npf, npf_cache_t *npc, struct mbuf **mp) 74 { 75 nbuf_t *nbuf = npc->npc_nbuf; 76 int error = EINVAL; 77 78 /* Reset the mbuf as it may have changed. */ 79 *mp = nbuf_head_mbuf(nbuf); 80 nbuf_reset(nbuf); 81 82 if (npf_iscached(npc, NPC_IP4)) { 83 struct ip *ip = nbuf_dataptr(nbuf); 84 error = ip_reass_packet(mp, ip); 85 } else if (npf_iscached(npc, NPC_IP6)) { 86 /* 87 * Note: ip6_reass_packet() offset is the start of 88 * the fragment header. 89 */ 90 error = ip6_reass_packet(mp, npc->npc_hlen); 91 if (error && *mp == NULL) { 92 memset(nbuf, 0, sizeof(nbuf_t)); 93 } 94 } 95 if (error) { 96 npf_stats_inc(npf, NPF_STAT_REASSFAIL); 97 return error; 98 } 99 if (*mp == NULL) { 100 /* More fragments should come. */ 101 npf_stats_inc(npf, NPF_STAT_FRAGMENTS); 102 return 0; 103 } 104 105 /* 106 * Reassembly is complete, we have the final packet. 107 * Cache again, since layer 4 data is accessible now. 108 */ 109 nbuf_init(npf, nbuf, *mp, nbuf->nb_ifp); 110 npc->npc_info = 0; 111 112 if (npf_cache_all(npc) & NPC_IPFRAG) { 113 return EINVAL; 114 } 115 npf_stats_inc(npf, NPF_STAT_REASSEMBLY); 116 return 0; 117 } 118 119 /* 120 * npf_packet_handler: main packet handling routine for layer 3. 121 * 122 * Note: packet flow and inspection logic is in strict order. 123 */ 124 __dso_public int 125 npf_packet_handler(npf_t *npf, struct mbuf **mp, ifnet_t *ifp, int di) 126 { 127 nbuf_t nbuf; 128 npf_cache_t npc; 129 npf_conn_t *con; 130 npf_rule_t *rl; 131 npf_rproc_t *rp; 132 int error, decision; 133 uint32_t ntag; 134 npf_match_info_t mi; 135 136 /* QSBR checkpoint. */ 137 pserialize_checkpoint(npf->qsbr); 138 KASSERT(ifp != NULL); 139 140 /* 141 * Initialise packet information cache. 142 * Note: it is enough to clear the info bits. 143 */ 144 npc.npc_ctx = npf; 145 nbuf_init(npf, &nbuf, *mp, ifp); 146 npc.npc_nbuf = &nbuf; 147 npc.npc_info = 0; 148 149 mi.mi_di = di; 150 mi.mi_rid = 0; 151 mi.mi_retfl = 0; 152 153 decision = NPF_DECISION_BLOCK; 154 error = 0; 155 rp = NULL; 156 157 /* Cache everything. Determine whether it is an IP fragment. */ 158 if (__predict_false(npf_cache_all(&npc) & NPC_IPFRAG)) { 159 /* 160 * Pass to IPv4 or IPv6 reassembly mechanism. 161 */ 162 error = npf_reassembly(npf, &npc, mp); 163 if (error) { 164 con = NULL; 165 goto out; 166 } 167 if (*mp == NULL) { 168 /* More fragments should come; return. */ 169 return 0; 170 } 171 } 172 173 /* Just pass-through if specially tagged. */ 174 if (nbuf_find_tag(&nbuf, &ntag) == 0 && (ntag & NPF_NTAG_PASS) != 0) { 175 con = NULL; 176 goto pass; 177 } 178 179 /* Inspect the list of connections (if found, acquires a reference). */ 180 con = npf_conn_inspect(&npc, di, &error); 181 182 /* If "passing" connection found - skip the ruleset inspection. */ 183 if (con && npf_conn_pass(con, &mi, &rp)) { 184 npf_stats_inc(npf, NPF_STAT_PASS_CONN); 185 KASSERT(error == 0); 186 goto pass; 187 } 188 if (__predict_false(error)) { 189 if (error == ENETUNREACH) 190 goto block; 191 goto out; 192 } 193 194 /* Acquire the lock, inspect the ruleset using this packet. */ 195 int slock = npf_config_read_enter(); 196 npf_ruleset_t *rlset = npf_config_ruleset(npf); 197 198 rl = npf_ruleset_inspect(&npc, rlset, di, NPF_LAYER_3); 199 if (__predict_false(rl == NULL)) { 200 const bool pass = npf_default_pass(npf); 201 npf_config_read_exit(slock); 202 203 if (pass) { 204 npf_stats_inc(npf, NPF_STAT_PASS_DEFAULT); 205 goto pass; 206 } 207 npf_stats_inc(npf, NPF_STAT_BLOCK_DEFAULT); 208 goto block; 209 } 210 211 /* 212 * Get the rule procedure (acquires a reference) for association 213 * with a connection (if any) and execution. 214 */ 215 KASSERT(rp == NULL); 216 rp = npf_rule_getrproc(rl); 217 218 /* Conclude with the rule and release the lock. */ 219 error = npf_rule_conclude(rl, &mi); 220 npf_config_read_exit(slock); 221 222 if (error) { 223 npf_stats_inc(npf, NPF_STAT_BLOCK_RULESET); 224 goto block; 225 } 226 npf_stats_inc(npf, NPF_STAT_PASS_RULESET); 227 228 /* 229 * Establish a "pass" connection, if required. Just proceed if 230 * connection creation fails (e.g. due to unsupported protocol). 231 */ 232 if ((mi.mi_retfl & NPF_RULE_STATEFUL) != 0 && !con) { 233 con = npf_conn_establish(&npc, di, 234 (mi.mi_retfl & NPF_RULE_MULTIENDS) == 0); 235 if (con) { 236 /* 237 * Note: the reference on the rule procedure is 238 * transfered to the connection. It will be 239 * released on connection destruction. 240 */ 241 npf_conn_setpass(con, &mi, rp); 242 } 243 } 244 pass: 245 decision = NPF_DECISION_PASS; 246 KASSERT(error == 0); 247 /* 248 * Perform NAT. 249 */ 250 error = npf_do_nat(&npc, con, di); 251 block: 252 /* 253 * Execute the rule procedure, if any is associated. 254 * It may reverse the decision from pass to block. 255 */ 256 if (rp && !npf_rproc_run(&npc, rp, &mi, &decision)) { 257 if (con) { 258 npf_conn_release(con); 259 } 260 npf_rproc_release(rp); 261 *mp = NULL; 262 return 0; 263 } 264 out: 265 /* 266 * Release the reference on a connection. Release the reference 267 * on a rule procedure only if there was no association. 268 */ 269 if (con) { 270 npf_conn_release(con); 271 } else if (rp) { 272 npf_rproc_release(rp); 273 } 274 275 /* Reset mbuf pointer before returning to the caller. */ 276 if ((*mp = nbuf_head_mbuf(&nbuf)) == NULL) { 277 return error ? error : ENOMEM; 278 } 279 280 /* Pass the packet if decided and there is no error. */ 281 if (decision == NPF_DECISION_PASS && !error) { 282 /* 283 * XXX: Disable for now, it will be set accordingly later, 284 * for optimisations (to reduce inspection). 285 */ 286 m_clear_flag(*mp, M_CANFASTFWD); 287 return 0; 288 } 289 290 /* 291 * Block the packet. ENETUNREACH is used to indicate blocking. 292 * Depending on the flags and protocol, return TCP reset (RST) or 293 * ICMP destination unreachable. 294 */ 295 if (mi.mi_retfl && npf_return_block(&npc, mi.mi_retfl)) { 296 *mp = NULL; 297 } 298 299 if (!error) { 300 error = ENETUNREACH; 301 } 302 303 if (*mp) { 304 /* Free the mbuf chain. */ 305 m_freem(*mp); 306 *mp = NULL; 307 } 308 return error; 309 } 310