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