1 /*- 2 * Copyright (c) 2019 Mindaugas Rasiukevicius <rmind at noxt eu> 3 * Copyright (c) 2013 The NetBSD Foundation, Inc. 4 * All rights reserved. 5 * 6 * This code is derived from software contributed to The NetBSD Foundation 7 * by Mindaugas Rasiukevicius. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28 * POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 /* 32 * NPF network interface handling. 33 * 34 * NPF uses its own interface IDs (npf-if-id). These IDs start from 1. 35 * Zero is reserved to indicate "no interface" case or an interface of 36 * no interest (i.e. not registered). 37 * 38 * This module provides an interface to primarily handle the following: 39 * 40 * - Bind a symbolic interface name to NPF interface ID. 41 * - Associate NPF interface ID when the network interface is attached. 42 * 43 * When NPF configuration is (re)loaded, each referenced network interface 44 * name is registered with a unique ID. If the network interface is already 45 * attached, then the ID is associated with it immediately; otherwise, IDs 46 * are associated/disassociated on interface events which are monitored 47 * using pfil(9) hooks. 48 * 49 * To avoid race conditions when an active NPF configuration is updated or 50 * interfaces are detached/attached, the interface names are never removed 51 * and therefore IDs are never re-assigned. The only point when interface 52 * names and IDs are cleared is when the configuration is flushed. 53 * 54 * A linear counter is used for IDs. 55 */ 56 57 #ifdef _KERNEL 58 #include <sys/cdefs.h> 59 __KERNEL_RCSID(0, "$NetBSD: npf_if.c,v 1.12 2019/09/30 22:04:33 rmind Exp $"); 60 61 #include <sys/param.h> 62 #include <sys/types.h> 63 #include <sys/kmem.h> 64 #include <net/if.h> 65 #endif 66 67 #include "npf_impl.h" 68 69 typedef struct npf_ifmap { 70 char ifname[IFNAMSIZ + 1]; 71 } npf_ifmap_t; 72 73 #define NPF_IFMAP_NOID (0U) 74 #define NPF_IFMAP_SLOT2ID(npf, slot) ((npf)->ifmap_off + (slot) + 1) 75 #define NPF_IFMAP_ID2SLOT(npf, id) ((id) - (npf)->ifmap_off - 1) 76 77 void 78 npf_ifmap_init(npf_t *npf, const npf_ifops_t *ifops) 79 { 80 const size_t nbytes = sizeof(npf_ifmap_t) * NPF_MAX_IFMAP; 81 82 KASSERT(ifops != NULL); 83 ifops->flush((void *)(uintptr_t)0); 84 85 mutex_init(&npf->ifmap_lock, MUTEX_DEFAULT, IPL_SOFTNET); 86 npf->ifmap = kmem_zalloc(nbytes, KM_SLEEP); 87 npf->ifmap_cnt = 0; 88 npf->ifmap_off = 0; 89 npf->ifops = ifops; 90 } 91 92 void 93 npf_ifmap_fini(npf_t *npf) 94 { 95 const size_t nbytes = sizeof(npf_ifmap_t) * NPF_MAX_IFMAP; 96 mutex_destroy(&npf->ifmap_lock); 97 kmem_free(npf->ifmap, nbytes); 98 } 99 100 static unsigned 101 npf_ifmap_lookup(npf_t *npf, const char *ifname) 102 { 103 KASSERT(mutex_owned(&npf->ifmap_lock)); 104 105 for (unsigned i = 0; i < npf->ifmap_cnt; i++) { 106 npf_ifmap_t *ifmap = &npf->ifmap[i]; 107 108 if (strcmp(ifmap->ifname, ifname) == 0) { 109 return NPF_IFMAP_SLOT2ID(npf, i); 110 } 111 } 112 return NPF_IFMAP_NOID; 113 } 114 115 /* 116 * npf_ifmap_register: register an interface name; return an assigned 117 * NPF network ID on success (non-zero). 118 * 119 * This routine is mostly called on NPF configuration (re)load for the 120 * interfaces names referenced by the rules. 121 */ 122 unsigned 123 npf_ifmap_register(npf_t *npf, const char *ifname) 124 { 125 npf_ifmap_t *ifmap; 126 unsigned id, i; 127 ifnet_t *ifp; 128 129 mutex_enter(&npf->ifmap_lock); 130 if ((id = npf_ifmap_lookup(npf, ifname)) != NPF_IFMAP_NOID) { 131 goto out; 132 } 133 if (npf->ifmap_cnt == NPF_MAX_IFMAP) { 134 printf("npf_ifmap_new: out of slots; bump NPF_MAX_IFMAP\n"); 135 id = NPF_IFMAP_NOID; 136 goto out; 137 } 138 KASSERT(npf->ifmap_cnt < NPF_MAX_IFMAP); 139 140 /* Allocate a new slot and convert and assign an ID. */ 141 i = npf->ifmap_cnt++; 142 ifmap = &npf->ifmap[i]; 143 strlcpy(ifmap->ifname, ifname, IFNAMSIZ); 144 id = NPF_IFMAP_SLOT2ID(npf, i); 145 146 if ((ifp = npf->ifops->lookup(ifname)) != NULL) { 147 npf->ifops->setmeta(ifp, (void *)(uintptr_t)id); 148 } 149 out: 150 mutex_exit(&npf->ifmap_lock); 151 return id; 152 } 153 154 void 155 npf_ifmap_flush(npf_t *npf) 156 { 157 mutex_enter(&npf->ifmap_lock); 158 npf->ifops->flush((void *)(uintptr_t)NPF_IFMAP_NOID); 159 for (unsigned i = 0; i < npf->ifmap_cnt; i++) { 160 npf->ifmap[i].ifname[0] = '\0'; 161 } 162 npf->ifmap_cnt = 0; 163 164 /* 165 * Reset the ID counter if reaching the overflow; this is not 166 * realistic, but we maintain correctness. 167 */ 168 if (npf->ifmap_off < (UINT_MAX - NPF_MAX_IFMAP)) { 169 npf->ifmap_off += NPF_MAX_IFMAP; 170 } else { 171 npf->ifmap_off = 0; 172 } 173 mutex_exit(&npf->ifmap_lock); 174 } 175 176 /* 177 * npf_ifmap_getid: get the ID for the given network interface. 178 * 179 * => This routine is typically called from the packet handler when 180 * matching whether the packet is on particular network interface. 181 * 182 * => This routine is lock-free; if the NPF configuration is flushed 183 * while the packet is in-flight, the ID will not match because we 184 * keep the IDs linear. 185 */ 186 unsigned 187 npf_ifmap_getid(npf_t *npf, const ifnet_t *ifp) 188 { 189 const unsigned id = (uintptr_t)npf->ifops->getmeta(ifp); 190 return id; 191 } 192 193 /* 194 * npf_ifmap_copylogname: this function is toxic; it can return garbage 195 * as we don't lock, but it is only used temporarily and only for logging. 196 */ 197 void 198 npf_ifmap_copylogname(npf_t *npf, unsigned id, char *buf, size_t len) 199 { 200 const unsigned i = NPF_IFMAP_ID2SLOT(npf, id); 201 202 membar_consumer(); 203 204 if (id != NPF_IFMAP_NOID && i < NPF_MAX_IFMAP) { 205 /* 206 * Lock-free access is safe as there is an extra byte 207 * with a permanent NUL terminator at the end. 208 */ 209 const npf_ifmap_t *ifmap = &npf->ifmap[i]; 210 strlcpy(buf, ifmap->ifname, MIN(len, IFNAMSIZ)); 211 } else { 212 strlcpy(buf, "???", len); 213 } 214 } 215 216 void 217 npf_ifmap_copyname(npf_t *npf, unsigned id, char *buf, size_t len) 218 { 219 mutex_enter(&npf->ifmap_lock); 220 npf_ifmap_copylogname(npf, id, buf, len); 221 mutex_exit(&npf->ifmap_lock); 222 } 223 224 __dso_public void 225 npfk_ifmap_attach(npf_t *npf, ifnet_t *ifp) 226 { 227 const npf_ifops_t *ifops = npf->ifops; 228 unsigned id; 229 230 mutex_enter(&npf->ifmap_lock); 231 id = npf_ifmap_lookup(npf, ifops->getname(ifp)); 232 ifops->setmeta(ifp, (void *)(uintptr_t)id); 233 mutex_exit(&npf->ifmap_lock); 234 } 235 236 __dso_public void 237 npfk_ifmap_detach(npf_t *npf, ifnet_t *ifp) 238 { 239 /* Diagnostic. */ 240 mutex_enter(&npf->ifmap_lock); 241 npf->ifops->setmeta(ifp, (void *)(uintptr_t)NPF_IFMAP_NOID); 242 mutex_exit(&npf->ifmap_lock); 243 } 244