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/route/shared.h> 50 #include <net/vnet.h> 51 52 /* 53 * This file contains data structures management logic for the nexthop ("nhop") 54 * route subsystem. 55 * 56 * Nexthops in the original sense are the objects containing all the necessary 57 * information to forward the packet to the selected destination. 58 * In particular, nexthop is defined by a combination of 59 * ifp, ifa, aifp, mtu, gw addr(if set), nh_type, nh_family, mask of rt_flags and 60 * NHF_DEFAULT 61 * 62 * All nexthops are stored in the resizable hash table. 63 * Additionally, each nexthop gets assigned its unique index (nexthop index) 64 * so userland programs can interact with the nexthops easier. Index allocation 65 * is backed by the bitmask array. 66 */ 67 68 static MALLOC_DEFINE(M_NHOP, "nhops", "nexthops data"); 69 70 71 /* Hash management functions */ 72 73 int 74 nhops_init_rib(struct rib_head *rh) 75 { 76 struct nh_control *ctl; 77 size_t alloc_size; 78 uint32_t num_buckets, num_items; 79 void *ptr; 80 81 ctl = malloc(sizeof(struct nh_control), M_NHOP, M_WAITOK | M_ZERO); 82 83 /* 84 * Allocate nexthop hash. Start with 16 items by default (128 bytes). 85 * This will be enough for most of the cases. 86 */ 87 num_buckets = 16; 88 alloc_size = CHT_SLIST_GET_RESIZE_SIZE(num_buckets); 89 ptr = malloc(alloc_size, M_NHOP, M_WAITOK | M_ZERO); 90 CHT_SLIST_INIT(&ctl->nh_head, ptr, num_buckets); 91 92 /* 93 * Allocate nexthop index bitmask. 94 */ 95 num_items = 128 * 8; /* 128 bytes */ 96 ptr = malloc(bitmask_get_size(num_items), M_NHOP, M_WAITOK | M_ZERO); 97 bitmask_init(&ctl->nh_idx_head, ptr, num_items); 98 99 NHOPS_LOCK_INIT(ctl); 100 101 rh->nh_control = ctl; 102 ctl->ctl_rh = rh; 103 104 DPRINTF("NHOPS init for fib %u af %u: ctl %p rh %p", rh->rib_fibnum, 105 rh->rib_family, ctl, rh); 106 107 return (0); 108 } 109 110 static void 111 destroy_ctl(struct nh_control *ctl) 112 { 113 114 NHOPS_LOCK_DESTROY(ctl); 115 free(ctl->nh_head.ptr, M_NHOP); 116 free(ctl->nh_idx_head.idx, M_NHOP); 117 free(ctl, M_NHOP); 118 } 119 120 /* 121 * Epoch callback indicating ctl is safe to destroy 122 */ 123 static void 124 destroy_ctl_epoch(epoch_context_t ctx) 125 { 126 struct nh_control *ctl; 127 128 ctl = __containerof(ctx, struct nh_control, ctl_epoch_ctx); 129 130 destroy_ctl(ctl); 131 } 132 133 void 134 nhops_destroy_rib(struct rib_head *rh) 135 { 136 struct nh_control *ctl; 137 struct nhop_priv *nh_priv; 138 139 ctl = rh->nh_control; 140 141 /* 142 * All routes should have been deleted in rt_table_destroy(). 143 * However, TCP stack or other consumers may store referenced 144 * nexthop pointers. When these references go to zero, 145 * nhop_free() will try to unlink these records from the 146 * datastructures, most likely leading to panic. 147 * 148 * Avoid that by explicitly marking all of the remaining 149 * nexthops as unlinked by removing a reference from a special 150 * counter. Please see nhop_free() comments for more 151 * details. 152 */ 153 154 NHOPS_WLOCK(ctl); 155 CHT_SLIST_FOREACH(&ctl->nh_head, nhops, nh_priv) { 156 DPRINTF("Marking nhop %u unlinked", nh_priv->nh_idx); 157 refcount_release(&nh_priv->nh_linked); 158 } CHT_SLIST_FOREACH_END; 159 NHOPS_WUNLOCK(ctl); 160 161 /* 162 * Postpone destruction till the end of current epoch 163 * so nhop_free() can safely use nh_control pointer. 164 */ 165 epoch_call(net_epoch_preempt, destroy_ctl_epoch, 166 &ctl->ctl_epoch_ctx); 167 } 168 169 /* 170 * Nexhop hash calculation: 171 * 172 * Nexthops distribution: 173 * 2 "mandatory" nexthops per interface ("interface route", "loopback"). 174 * For direct peering: 1 nexthop for the peering router per ifp/af. 175 * For Ix-like peering: tens to hundreds nexthops of neghbors per ifp/af. 176 * IGP control plane & broadcast segment: tens of nexthops per ifp/af. 177 * 178 * Each fib/af combination has its own hash table. 179 * With that in mind, hash nexthops by the combination of the interface 180 * and GW IP address. 181 * 182 * To optimize hash calculation, ignore higher bytes of ifindex, as they 183 * give very little entropy. 184 * Similarly, use lower 4 bytes of IPv6 address to distinguish between the 185 * neighbors. 186 */ 187 struct _hash_data { 188 uint16_t ifindex; 189 uint8_t family; 190 uint8_t nh_type; 191 uint32_t gw_addr; 192 }; 193 194 static unsigned 195 djb_hash(const unsigned char *h, const int len) 196 { 197 unsigned int result = 0; 198 int i; 199 200 for (i = 0; i < len; i++) 201 result = 33 * result ^ h[i]; 202 203 return (result); 204 } 205 206 static uint32_t 207 hash_priv(const struct nhop_priv *priv) 208 { 209 struct nhop_object *nh; 210 uint16_t ifindex; 211 struct _hash_data key; 212 213 nh = priv->nh; 214 ifindex = nh->nh_ifp->if_index & 0xFFFF; 215 memset(&key, 0, sizeof(key)); 216 217 key.ifindex = ifindex; 218 key.family = nh->gw_sa.sa_family; 219 key.nh_type = priv->nh_type & 0xFF; 220 if (nh->gw_sa.sa_family == AF_INET6) 221 memcpy(&key.gw_addr, &nh->gw6_sa.sin6_addr.s6_addr32[3], 4); 222 else if (nh->gw_sa.sa_family == AF_INET) 223 memcpy(&key.gw_addr, &nh->gw4_sa.sin_addr, 4); 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 DPRINTF("going to resize: nh:[ptr:%p sz:%u] idx:[ptr:%p sz:%u]", nh_ptr, 257 new_nh_buckets, nh_idx_ptr, new_idx_items); 258 259 old_idx_ptr = NULL; 260 261 NHOPS_WLOCK(ctl); 262 if (nh_ptr != NULL) { 263 CHT_SLIST_RESIZE(&ctl->nh_head, nhops, nh_ptr, new_nh_buckets); 264 } 265 if (nh_idx_ptr != NULL) { 266 if (bitmask_copy(&ctl->nh_idx_head, nh_idx_ptr, new_idx_items) == 0) 267 bitmask_swap(&ctl->nh_idx_head, nh_idx_ptr, new_idx_items, &old_idx_ptr); 268 } 269 NHOPS_WUNLOCK(ctl); 270 271 if (nh_ptr != NULL) 272 free(nh_ptr, M_NHOP); 273 if (old_idx_ptr != NULL) 274 free(old_idx_ptr, M_NHOP); 275 } 276 277 /* 278 * Links nextop @nh_priv to the nexhop hash table and allocates 279 * nexhop index. 280 * Returns allocated index or 0 on failure. 281 */ 282 int 283 link_nhop(struct nh_control *ctl, struct nhop_priv *nh_priv) 284 { 285 uint16_t idx; 286 uint32_t num_buckets_new, num_items_new; 287 288 KASSERT((nh_priv->nh_idx == 0), ("nhop index is already allocated")); 289 NHOPS_WLOCK(ctl); 290 291 /* 292 * Check if we need to resize hash and index. 293 * The following 2 functions returns either new size or 0 294 * if resize is not required. 295 */ 296 num_buckets_new = CHT_SLIST_GET_RESIZE_BUCKETS(&ctl->nh_head); 297 num_items_new = bitmask_get_resize_items(&ctl->nh_idx_head); 298 299 if (bitmask_alloc_idx(&ctl->nh_idx_head, &idx) != 0) { 300 NHOPS_WUNLOCK(ctl); 301 DPRINTF("Unable to allocate nhop index"); 302 RTSTAT_INC(rts_nh_idx_alloc_failure); 303 consider_resize(ctl, num_buckets_new, num_items_new); 304 return (0); 305 } 306 307 nh_priv->nh_idx = idx; 308 nh_priv->nh_control = ctl; 309 310 CHT_SLIST_INSERT_HEAD(&ctl->nh_head, nhops, nh_priv); 311 312 NHOPS_WUNLOCK(ctl); 313 314 DPRINTF("Linked nhop priv %p to %d, hash %u, ctl %p", nh_priv, idx, 315 hash_priv(nh_priv), ctl); 316 consider_resize(ctl, num_buckets_new, num_items_new); 317 318 return (idx); 319 } 320 321 /* 322 * Unlinks nexthop specified by @nh_priv data from the hash. 323 * 324 * Returns found nexthop or NULL. 325 */ 326 struct nhop_priv * 327 unlink_nhop(struct nh_control *ctl, struct nhop_priv *nh_priv_del) 328 { 329 struct nhop_priv *priv_ret; 330 int idx; 331 uint32_t num_buckets_new, num_items_new; 332 333 idx = 0; 334 335 NHOPS_WLOCK(ctl); 336 CHT_SLIST_REMOVE_BYOBJ(&ctl->nh_head, nhops, nh_priv_del, priv_ret); 337 338 if (priv_ret != NULL) { 339 idx = priv_ret->nh_idx; 340 priv_ret->nh_idx = 0; 341 342 KASSERT((idx != 0), ("bogus nhop index 0")); 343 if ((bitmask_free_idx(&ctl->nh_idx_head, idx)) != 0) { 344 DPRINTF("Unable to remove index %d from fib %u af %d", 345 idx, ctl->ctl_rh->rib_fibnum, 346 ctl->ctl_rh->rib_family); 347 } 348 } 349 350 /* Check if hash or index needs to be resized */ 351 num_buckets_new = CHT_SLIST_GET_RESIZE_BUCKETS(&ctl->nh_head); 352 num_items_new = bitmask_get_resize_items(&ctl->nh_idx_head); 353 354 NHOPS_WUNLOCK(ctl); 355 356 if (priv_ret == NULL) 357 DPRINTF("Unable to unlink nhop priv %p from hash, hash %u ctl %p", 358 nh_priv_del, hash_priv(nh_priv_del), ctl); 359 else 360 DPRINTF("Unlinked nhop %p priv idx %d", priv_ret, idx); 361 362 consider_resize(ctl, num_buckets_new, num_items_new); 363 364 return (priv_ret); 365 } 366 367 /* 368 * Searches for the nexthop by data specifcied in @nh_priv. 369 * Returns referenced nexthop or NULL. 370 */ 371 struct nhop_priv * 372 find_nhop(struct nh_control *ctl, const struct nhop_priv *nh_priv) 373 { 374 struct nhop_priv *nh_priv_ret; 375 376 NHOPS_RLOCK(ctl); 377 CHT_SLIST_FIND_BYOBJ(&ctl->nh_head, nhops, nh_priv, nh_priv_ret); 378 if (nh_priv_ret != NULL) { 379 if (refcount_acquire_if_not_zero(&nh_priv_ret->nh_refcnt) == 0){ 380 /* refcount was 0 -> nhop is being deleted */ 381 nh_priv_ret = NULL; 382 } 383 } 384 NHOPS_RUNLOCK(ctl); 385 386 return (nh_priv_ret); 387 } 388 389