1 /* $NetBSD: npf_handler.c,v 1.44 2018/07/10 16:49:09 maxv 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 1.44 2018/07/10 16:49:09 maxv 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, bool *mff) 74 { 75 nbuf_t *nbuf = npc->npc_nbuf; 76 int error = EINVAL; 77 struct mbuf *m; 78 79 *mff = false; 80 m = nbuf_head_mbuf(nbuf); 81 82 if (npf_iscached(npc, NPC_IP4)) { 83 error = ip_reass_packet(&m); 84 } else if (npf_iscached(npc, NPC_IP6)) { 85 error = ip6_reass_packet(&m, npc->npc_hlen); 86 } 87 88 if (error) { 89 /* Reass failed. Free the mbuf, clear the nbuf. */ 90 npf_stats_inc(npf, NPF_STAT_REASSFAIL); 91 m_freem(m); 92 memset(nbuf, 0, sizeof(nbuf_t)); 93 return error; 94 } 95 if (m == NULL) { 96 /* More fragments should come. */ 97 npf_stats_inc(npf, NPF_STAT_FRAGMENTS); 98 *mff = true; 99 return 0; 100 } 101 102 /* 103 * Reassembly is complete, we have the final packet. 104 * Cache again, since layer 4 data is accessible now. 105 */ 106 nbuf_init(npf, nbuf, m, nbuf->nb_ifp); 107 npc->npc_info = 0; 108 109 if (npf_cache_all(npc) & (NPC_IPFRAG|NPC_FMTERR)) { 110 return EINVAL; 111 } 112 npf_stats_inc(npf, NPF_STAT_REASSEMBLY); 113 return 0; 114 } 115 116 /* 117 * npf_packet_handler: main packet handling routine for layer 3. 118 * 119 * Note: packet flow and inspection logic is in strict order. 120 */ 121 __dso_public int 122 npf_packet_handler(npf_t *npf, struct mbuf **mp, ifnet_t *ifp, int di) 123 { 124 nbuf_t nbuf; 125 npf_cache_t npc; 126 npf_conn_t *con; 127 npf_rule_t *rl; 128 npf_rproc_t *rp; 129 int error, decision, flags; 130 uint32_t ntag; 131 npf_match_info_t mi; 132 bool mff; 133 134 /* QSBR checkpoint. */ 135 pserialize_checkpoint(npf->qsbr); 136 KASSERT(ifp != NULL); 137 138 /* 139 * Initialise packet information cache. 140 * Note: it is enough to clear the info bits. 141 */ 142 npc.npc_ctx = npf; 143 nbuf_init(npf, &nbuf, *mp, ifp); 144 npc.npc_nbuf = &nbuf; 145 npc.npc_info = 0; 146 147 mi.mi_di = di; 148 mi.mi_rid = 0; 149 mi.mi_retfl = 0; 150 151 *mp = NULL; 152 decision = NPF_DECISION_BLOCK; 153 error = 0; 154 rp = NULL; 155 con = NULL; 156 157 /* Cache everything. */ 158 flags = npf_cache_all(&npc); 159 160 /* If error on the format, leave quickly. */ 161 if (flags & NPC_FMTERR) { 162 error = EINVAL; 163 goto out; 164 } 165 166 /* Determine whether it is an IP fragment. */ 167 if (__predict_false(flags & NPC_IPFRAG)) { 168 /* Pass to IPv4/IPv6 reassembly mechanism. */ 169 error = npf_reassembly(npf, &npc, &mff); 170 if (error) { 171 goto out; 172 } 173 if (mff) { 174 /* More fragments should come. */ 175 return 0; 176 } 177 } 178 179 /* Just pass-through if specially tagged. */ 180 if (nbuf_find_tag(&nbuf, &ntag) == 0 && (ntag & NPF_NTAG_PASS) != 0) { 181 goto pass; 182 } 183 184 /* Inspect the list of connections (if found, acquires a reference). */ 185 con = npf_conn_inspect(&npc, di, &error); 186 187 /* If "passing" connection found - skip the ruleset inspection. */ 188 if (con && npf_conn_pass(con, &mi, &rp)) { 189 npf_stats_inc(npf, NPF_STAT_PASS_CONN); 190 KASSERT(error == 0); 191 goto pass; 192 } 193 if (__predict_false(error)) { 194 if (error == ENETUNREACH) 195 goto block; 196 goto out; 197 } 198 199 /* Acquire the lock, inspect the ruleset using this packet. */ 200 int slock = npf_config_read_enter(); 201 npf_ruleset_t *rlset = npf_config_ruleset(npf); 202 203 rl = npf_ruleset_inspect(&npc, rlset, di, NPF_LAYER_3); 204 if (__predict_false(rl == NULL)) { 205 const bool pass = npf_default_pass(npf); 206 npf_config_read_exit(slock); 207 208 if (pass) { 209 npf_stats_inc(npf, NPF_STAT_PASS_DEFAULT); 210 goto pass; 211 } 212 npf_stats_inc(npf, NPF_STAT_BLOCK_DEFAULT); 213 goto block; 214 } 215 216 /* 217 * Get the rule procedure (acquires a reference) for association 218 * with a connection (if any) and execution. 219 */ 220 KASSERT(rp == NULL); 221 rp = npf_rule_getrproc(rl); 222 223 /* Conclude with the rule and release the lock. */ 224 error = npf_rule_conclude(rl, &mi); 225 npf_config_read_exit(slock); 226 227 if (error) { 228 npf_stats_inc(npf, NPF_STAT_BLOCK_RULESET); 229 goto block; 230 } 231 npf_stats_inc(npf, NPF_STAT_PASS_RULESET); 232 233 /* 234 * Establish a "pass" connection, if required. Just proceed if 235 * connection creation fails (e.g. due to unsupported protocol). 236 */ 237 if ((mi.mi_retfl & NPF_RULE_STATEFUL) != 0 && !con) { 238 con = npf_conn_establish(&npc, di, 239 (mi.mi_retfl & NPF_RULE_MULTIENDS) == 0); 240 if (con) { 241 /* 242 * Note: the reference on the rule procedure is 243 * transfered to the connection. It will be 244 * released on connection destruction. 245 */ 246 npf_conn_setpass(con, &mi, rp); 247 } 248 } 249 250 pass: 251 decision = NPF_DECISION_PASS; 252 KASSERT(error == 0); 253 /* 254 * Perform NAT. 255 */ 256 error = npf_do_nat(&npc, con, di); 257 258 block: 259 /* 260 * Execute the rule procedure, if any is associated. 261 * It may reverse the decision from pass to block. 262 */ 263 if (rp && !npf_rproc_run(&npc, rp, &mi, &decision)) { 264 if (con) { 265 npf_conn_release(con); 266 } 267 npf_rproc_release(rp); 268 /* mbuf already freed */ 269 return 0; 270 } 271 272 out: 273 /* 274 * Release the reference on a connection. Release the reference 275 * on a rule procedure only if there was no association. 276 */ 277 if (con) { 278 npf_conn_release(con); 279 } else if (rp) { 280 npf_rproc_release(rp); 281 } 282 283 /* Get the new mbuf pointer. */ 284 if ((*mp = nbuf_head_mbuf(&nbuf)) == NULL) { 285 return error ? error : ENOMEM; 286 } 287 288 /* Pass the packet if decided and there is no error. */ 289 if (decision == NPF_DECISION_PASS && !error) { 290 /* 291 * XXX: Disable for now, it will be set accordingly later, 292 * for optimisations (to reduce inspection). 293 */ 294 m_clear_flag(*mp, M_CANFASTFWD); 295 return 0; 296 } 297 298 /* 299 * Block the packet. ENETUNREACH is used to indicate blocking. 300 * Depending on the flags and protocol, return TCP reset (RST) or 301 * ICMP destination unreachable. 302 */ 303 if (mi.mi_retfl && npf_return_block(&npc, mi.mi_retfl)) { 304 *mp = NULL; 305 } 306 307 if (!error) { 308 error = ENETUNREACH; 309 } 310 311 if (*mp) { 312 /* Free the mbuf chain. */ 313 m_freem(*mp); 314 *mp = NULL; 315 } 316 return error; 317 } 318