1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2020 Alexander V. Chernikov 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 #include <sys/cdefs.h> 29 #include "opt_inet.h" 30 #include "opt_route.h" 31 32 #include <sys/param.h> 33 #include <sys/systm.h> 34 #include <sys/lock.h> 35 #include <sys/rwlock.h> 36 #include <sys/malloc.h> 37 #include <sys/mbuf.h> 38 #include <sys/socket.h> 39 #include <sys/kernel.h> 40 41 #include <net/if.h> 42 #include <net/if_var.h> 43 #include <net/route.h> 44 #include <net/route/route_var.h> 45 #include <net/route/nhop_utils.h> 46 #include <net/route/nhop.h> 47 #include <net/route/nhop_var.h> 48 #include <net/vnet.h> 49 50 #define DEBUG_MOD_NAME nhop 51 #define DEBUG_MAX_LEVEL LOG_DEBUG 52 #include <net/route/route_debug.h> 53 _DECLARE_DEBUG(LOG_INFO); 54 55 /* 56 * This file contains data structures management logic for the nexthop ("nhop") 57 * route subsystem. 58 * 59 * Nexthops in the original sense are the objects containing all the necessary 60 * information to forward the packet to the selected destination. 61 * In particular, nexthop is defined by a combination of 62 * ifp, ifa, aifp, mtu, gw addr(if set), nh_type, nh_family, mask of rt_flags and 63 * NHF_DEFAULT 64 * 65 * All nexthops are stored in the resizable hash table. 66 * Additionally, each nexthop gets assigned its unique index (nexthop index) 67 * so userland programs can interact with the nexthops easier. Index allocation 68 * is backed by the bitmask array. 69 */ 70 71 MALLOC_DEFINE(M_NHOP, "nhops", "nexthops data"); 72 73 /* Hash management functions */ 74 75 int 76 nhops_init_rib(struct rib_head *rh) 77 { 78 struct nh_control *ctl; 79 size_t alloc_size; 80 uint32_t num_buckets, num_items; 81 void *ptr; 82 83 ctl = malloc(sizeof(struct nh_control), M_NHOP, M_WAITOK | M_ZERO); 84 85 /* 86 * Allocate nexthop hash. Start with 16 items by default (128 bytes). 87 * This will be enough for most of the cases. 88 */ 89 num_buckets = 16; 90 alloc_size = CHT_SLIST_GET_RESIZE_SIZE(num_buckets); 91 ptr = malloc(alloc_size, M_NHOP, M_WAITOK | M_ZERO); 92 CHT_SLIST_INIT(&ctl->nh_head, ptr, num_buckets); 93 94 /* 95 * Allocate nexthop index bitmask. 96 */ 97 num_items = 128 * 8; /* 128 bytes */ 98 ptr = malloc(bitmask_get_size(num_items), M_NHOP, M_WAITOK | M_ZERO); 99 bitmask_init(&ctl->nh_idx_head, ptr, num_items); 100 101 NHOPS_LOCK_INIT(ctl); 102 103 rh->nh_control = ctl; 104 ctl->ctl_rh = rh; 105 106 FIB_CTL_LOG(LOG_DEBUG2, ctl, "nhops init: ctl %p rh %p", ctl, rh); 107 108 return (0); 109 } 110 111 static void 112 destroy_ctl(struct nh_control *ctl) 113 { 114 115 NHOPS_LOCK_DESTROY(ctl); 116 free(ctl->nh_head.ptr, M_NHOP); 117 free(ctl->nh_idx_head.idx, M_NHOP); 118 #ifdef ROUTE_MPATH 119 nhgrp_ctl_free(ctl); 120 #endif 121 free(ctl, M_NHOP); 122 } 123 124 /* 125 * Epoch callback indicating ctl is safe to destroy 126 */ 127 static void 128 destroy_ctl_epoch(epoch_context_t ctx) 129 { 130 struct nh_control *ctl; 131 132 ctl = __containerof(ctx, struct nh_control, ctl_epoch_ctx); 133 134 destroy_ctl(ctl); 135 } 136 137 void 138 nhops_destroy_rib(struct rib_head *rh) 139 { 140 struct nh_control *ctl; 141 struct nhop_priv *nh_priv; 142 143 ctl = rh->nh_control; 144 145 /* 146 * All routes should have been deleted in rt_table_destroy(). 147 * However, TCP stack or other consumers may store referenced 148 * nexthop pointers. When these references go to zero, 149 * nhop_free() will try to unlink these records from the 150 * datastructures, most likely leading to panic. 151 * 152 * Avoid that by explicitly marking all of the remaining 153 * nexthops as unlinked by removing a reference from a special 154 * counter. Please see nhop_free() comments for more 155 * details. 156 */ 157 158 NHOPS_WLOCK(ctl); 159 CHT_SLIST_FOREACH(&ctl->nh_head, nhops, nh_priv) { 160 FIB_RH_LOG(LOG_DEBUG3, rh, "marking nhop %u unlinked", nh_priv->nh_idx); 161 refcount_release(&nh_priv->nh_linked); 162 } CHT_SLIST_FOREACH_END; 163 #ifdef ROUTE_MPATH 164 nhgrp_ctl_unlink_all(ctl); 165 #endif 166 NHOPS_WUNLOCK(ctl); 167 168 /* 169 * Postpone destruction till the end of current epoch 170 * so nhop_free() can safely use nh_control pointer. 171 */ 172 NET_EPOCH_CALL(destroy_ctl_epoch, &ctl->ctl_epoch_ctx); 173 } 174 175 /* 176 * Nexhop hash calculation: 177 * 178 * Nexthops distribution: 179 * 2 "mandatory" nexthops per interface ("interface route", "loopback"). 180 * For direct peering: 1 nexthop for the peering router per ifp/af. 181 * For Ix-like peering: tens to hundreds nexthops of neghbors per ifp/af. 182 * IGP control plane & broadcast segment: tens of nexthops per ifp/af. 183 * 184 * Each fib/af combination has its own hash table. 185 * With that in mind, hash nexthops by the combination of the interface 186 * and GW IP address. 187 * 188 * To optimize hash calculation, ignore lower bits of ifnet pointer, 189 * as they give very little entropy. 190 * Similarly, use lower 4 bytes of IPv6 address to distinguish between the 191 * neighbors. 192 */ 193 struct _hash_data { 194 uint16_t ifentropy; 195 uint8_t family; 196 uint8_t nh_type; 197 uint32_t gw_addr; 198 }; 199 200 static unsigned 201 djb_hash(const unsigned char *h, const int len) 202 { 203 unsigned int result = 0; 204 int i; 205 206 for (i = 0; i < len; i++) 207 result = 33 * result ^ h[i]; 208 209 return (result); 210 } 211 212 static uint32_t 213 hash_priv(const struct nhop_priv *priv) 214 { 215 struct nhop_object *nh = priv->nh; 216 struct _hash_data key = { 217 .ifentropy = (uint16_t)((((uintptr_t)nh->nh_ifp) >> 6) & 0xFFFF), 218 .family = nh->gw_sa.sa_family, 219 .nh_type = priv->nh_type & 0xFF, 220 .gw_addr = (nh->gw_sa.sa_family == AF_INET6) ? 221 nh->gw6_sa.sin6_addr.s6_addr32[3] : 222 nh->gw4_sa.sin_addr.s_addr 223 }; 224 225 return (uint32_t)(djb_hash((const unsigned char *)&key, sizeof(key))); 226 } 227 228 /* 229 * Checks if hash needs resizing and performs this resize if necessary 230 * 231 */ 232 static void 233 consider_resize(struct nh_control *ctl, uint32_t new_nh_buckets, uint32_t new_idx_items) 234 { 235 void *nh_ptr, *nh_idx_ptr; 236 void *old_idx_ptr; 237 size_t alloc_size; 238 239 nh_ptr = NULL; 240 if (new_nh_buckets != 0) { 241 alloc_size = CHT_SLIST_GET_RESIZE_SIZE(new_nh_buckets); 242 nh_ptr = malloc(alloc_size, M_NHOP, M_NOWAIT | M_ZERO); 243 } 244 245 nh_idx_ptr = NULL; 246 if (new_idx_items != 0) { 247 alloc_size = bitmask_get_size(new_idx_items); 248 nh_idx_ptr = malloc(alloc_size, M_NHOP, M_NOWAIT | M_ZERO); 249 } 250 251 if (nh_ptr == NULL && nh_idx_ptr == NULL) { 252 /* Either resize is not required or allocations have failed. */ 253 return; 254 } 255 256 FIB_CTL_LOG(LOG_DEBUG, ctl, 257 "going to resize: nh:[ptr:%p sz:%u] idx:[ptr:%p sz:%u]", 258 nh_ptr, new_nh_buckets, nh_idx_ptr, new_idx_items); 259 260 old_idx_ptr = NULL; 261 262 NHOPS_WLOCK(ctl); 263 if (nh_ptr != NULL) { 264 CHT_SLIST_RESIZE(&ctl->nh_head, nhops, nh_ptr, new_nh_buckets); 265 } 266 if (nh_idx_ptr != NULL) { 267 if (bitmask_copy(&ctl->nh_idx_head, nh_idx_ptr, new_idx_items) == 0) 268 bitmask_swap(&ctl->nh_idx_head, nh_idx_ptr, new_idx_items, &old_idx_ptr); 269 } 270 NHOPS_WUNLOCK(ctl); 271 272 if (nh_ptr != NULL) 273 free(nh_ptr, M_NHOP); 274 if (old_idx_ptr != NULL) 275 free(old_idx_ptr, M_NHOP); 276 } 277 278 /* 279 * Links nextop @nh_priv to the nexhop hash table and allocates 280 * nexhop index. 281 * Returns allocated index or 0 on failure. 282 */ 283 int 284 link_nhop(struct nh_control *ctl, struct nhop_priv *nh_priv) 285 { 286 uint16_t idx; 287 uint32_t num_buckets_new, num_items_new; 288 289 KASSERT((nh_priv->nh_idx == 0), ("nhop index is already allocated")); 290 NHOPS_WLOCK(ctl); 291 292 /* 293 * Check if we need to resize hash and index. 294 * The following 2 functions returns either new size or 0 295 * if resize is not required. 296 */ 297 num_buckets_new = CHT_SLIST_GET_RESIZE_BUCKETS(&ctl->nh_head); 298 num_items_new = bitmask_get_resize_items(&ctl->nh_idx_head); 299 300 if (bitmask_alloc_idx(&ctl->nh_idx_head, &idx) != 0) { 301 NHOPS_WUNLOCK(ctl); 302 FIB_CTL_LOG(LOG_INFO, ctl, "Unable to allocate nhop index"); 303 RTSTAT_INC(rts_nh_idx_alloc_failure); 304 consider_resize(ctl, num_buckets_new, num_items_new); 305 return (0); 306 } 307 308 nh_priv->nh_idx = idx; 309 nh_priv->nh_control = ctl; 310 nh_priv->nh_finalized = 1; 311 312 CHT_SLIST_INSERT_HEAD(&ctl->nh_head, nhops, nh_priv); 313 314 NHOPS_WUNLOCK(ctl); 315 316 FIB_RH_LOG(LOG_DEBUG2, ctl->ctl_rh, 317 "Linked nhop priv %p to %d, hash %u, ctl %p", 318 nh_priv, idx, hash_priv(nh_priv), ctl); 319 consider_resize(ctl, num_buckets_new, num_items_new); 320 321 return (idx); 322 } 323 324 /* 325 * Unlinks nexthop specified by @nh_priv data from the hash. 326 * 327 * Returns found nexthop or NULL. 328 */ 329 struct nhop_priv * 330 unlink_nhop(struct nh_control *ctl, struct nhop_priv *nh_priv_del) 331 { 332 struct nhop_priv *priv_ret; 333 int idx; 334 uint32_t num_buckets_new, num_items_new; 335 336 idx = 0; 337 338 NHOPS_WLOCK(ctl); 339 CHT_SLIST_REMOVE(&ctl->nh_head, nhops, nh_priv_del, priv_ret); 340 341 if (priv_ret != NULL) { 342 idx = priv_ret->nh_idx; 343 priv_ret->nh_idx = 0; 344 345 KASSERT((idx != 0), ("bogus nhop index 0")); 346 if ((bitmask_free_idx(&ctl->nh_idx_head, idx)) != 0) { 347 FIB_CTL_LOG(LOG_DEBUG, ctl, 348 "Unable to remove index %d from fib %u af %d", 349 idx, ctl->ctl_rh->rib_fibnum, ctl->ctl_rh->rib_family); 350 } 351 } 352 353 /* Check if hash or index needs to be resized */ 354 num_buckets_new = CHT_SLIST_GET_RESIZE_BUCKETS(&ctl->nh_head); 355 num_items_new = bitmask_get_resize_items(&ctl->nh_idx_head); 356 357 NHOPS_WUNLOCK(ctl); 358 359 if (priv_ret == NULL) { 360 FIB_CTL_LOG(LOG_INFO, ctl, 361 "Unable to unlink nhop priv %p from hash, hash %u ctl %p", 362 nh_priv_del, hash_priv(nh_priv_del), ctl); 363 } else { 364 FIB_CTL_LOG(LOG_DEBUG2, ctl, "Unlinked nhop %p priv idx %d", 365 priv_ret, idx); 366 } 367 368 consider_resize(ctl, num_buckets_new, num_items_new); 369 370 return (priv_ret); 371 } 372 373 /* 374 * Searches for the nexthop by data specifcied in @nh_priv. 375 * Returns referenced nexthop or NULL. 376 */ 377 struct nhop_priv * 378 find_nhop(struct nh_control *ctl, const struct nhop_priv *nh_priv) 379 { 380 struct nhop_priv *nh_priv_ret; 381 382 NHOPS_RLOCK(ctl); 383 CHT_SLIST_FIND_BYOBJ(&ctl->nh_head, nhops, nh_priv, nh_priv_ret); 384 if (nh_priv_ret != NULL) { 385 if (refcount_acquire_if_not_zero(&nh_priv_ret->nh_refcnt) == 0){ 386 /* refcount was 0 -> nhop is being deleted */ 387 nh_priv_ret = NULL; 388 } 389 } 390 NHOPS_RUNLOCK(ctl); 391 392 return (nh_priv_ret); 393 } 394