1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 2002 Andre Oppermann, Internet Business Solutions AG
5 * Copyright (c) 2021 Gleb Smirnoff <glebius@FreeBSD.org>
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. The name of the author may not be used to endorse or promote
17 * products derived from this software without specific prior written
18 * permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 /*
34 * The tcp_hostcache moves the tcp-specific cached metrics from the routing
35 * table to a dedicated structure indexed by the remote IP address. It keeps
36 * information on the measured TCP parameters of past TCP sessions to allow
37 * better initial start values to be used with later connections to/from the
38 * same source. Depending on the network parameters (delay, max MTU,
39 * congestion window) between local and remote sites, this can lead to
40 * significant speed-ups for new TCP connections after the first one.
41 *
42 * Due to the tcp_hostcache, all TCP-specific metrics information in the
43 * routing table have been removed. The inpcb no longer keeps a pointer to
44 * the routing entry, and protocol-initiated route cloning has been removed
45 * as well. With these changes, the routing table has gone back to being
46 * more lightwight and only carries information related to packet forwarding.
47 *
48 * tcp_hostcache is designed for multiple concurrent access in SMP
49 * environments and high contention. It is a straight hash. Each bucket row
50 * is protected by its own lock for modification. Readers are protected by
51 * SMR. This puts certain restrictions on writers, e.g. a writer shall only
52 * insert a fully populated entry into a row. Writer can't reuse least used
53 * entry if a hash is full. Value updates for an entry shall be atomic.
54 *
55 * TCP stack(s) communication with tcp_hostcache() is done via KBI functions
56 * tcp_hc_*() and the hc_metrics_lite structure.
57 *
58 * Since tcp_hostcache is only caching information, there are no fatal
59 * consequences if we either can't allocate a new entry or have to drop
60 * an existing entry, or return somewhat stale information.
61 */
62
63 /*
64 * Many thanks to jlemon for basic structure of tcp_syncache which is being
65 * followed here.
66 */
67
68 #include "opt_inet6.h"
69
70 #include <sys/param.h>
71 #include <sys/systm.h>
72 #include <sys/hash.h>
73 #include <sys/jail.h>
74 #include <sys/kernel.h>
75 #include <sys/lock.h>
76 #include <sys/mutex.h>
77 #include <sys/malloc.h>
78 #include <sys/proc.h>
79 #include <sys/sbuf.h>
80 #include <sys/smr.h>
81 #include <sys/socket.h>
82 #include <sys/sysctl.h>
83
84 #include <net/vnet.h>
85
86 #include <netinet/in.h>
87 #include <netinet/in_pcb.h>
88 #include <netinet/tcp.h>
89 #include <netinet/tcp_var.h>
90
91 #include <vm/uma.h>
92
93 struct hc_head {
94 CK_SLIST_HEAD(hc_qhead, hc_metrics) hch_bucket;
95 u_int hch_length;
96 struct mtx hch_mtx;
97 };
98
99 struct hc_metrics {
100 /* housekeeping */
101 CK_SLIST_ENTRY(hc_metrics) hc_q;
102 struct in_addr ip4; /* IP address */
103 struct in6_addr ip6; /* IP6 address */
104 uint32_t ip6_zoneid; /* IPv6 scope zone id */
105 /* endpoint specific values for tcp */
106 uint32_t hc_mtu; /* MTU for this path */
107 uint32_t hc_ssthresh; /* outbound gateway buffer limit */
108 uint32_t hc_rtt; /* estimated round trip time */
109 uint32_t hc_rttvar; /* estimated rtt variance */
110 uint32_t hc_cwnd; /* congestion window */
111 uint32_t hc_sendpipe; /* outbound delay-bandwidth product */
112 uint32_t hc_recvpipe; /* inbound delay-bandwidth product */
113 /* TCP hostcache internal data */
114 int hc_expire; /* lifetime for object */
115 #ifdef TCP_HC_COUNTERS
116 u_long hc_hits; /* number of hits */
117 u_long hc_updates; /* number of updates */
118 #endif
119 };
120
121 struct tcp_hostcache {
122 struct hc_head *hashbase;
123 uma_zone_t zone;
124 smr_t smr;
125 u_int hashsize;
126 u_int hashmask;
127 u_int hashsalt;
128 u_int bucket_limit;
129 u_int cache_count;
130 u_int cache_limit;
131 int expire;
132 int prune;
133 int purgeall;
134 };
135
136 /* Arbitrary values */
137 #define TCP_HOSTCACHE_HASHSIZE 512
138 #define TCP_HOSTCACHE_BUCKETLIMIT 30
139 #define TCP_HOSTCACHE_EXPIRE 60*60 /* one hour */
140 #define TCP_HOSTCACHE_PRUNE 5*60 /* every 5 minutes */
141
142 VNET_DEFINE_STATIC(struct tcp_hostcache, tcp_hostcache);
143 #define V_tcp_hostcache VNET(tcp_hostcache)
144
145 VNET_DEFINE_STATIC(struct callout, tcp_hc_callout);
146 #define V_tcp_hc_callout VNET(tcp_hc_callout)
147
148 static struct hc_metrics *tcp_hc_lookup(const struct in_conninfo *);
149 static int sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS);
150 static int sysctl_tcp_hc_histo(SYSCTL_HANDLER_ARGS);
151 static int sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS);
152 static void tcp_hc_purge_internal(int);
153 static void tcp_hc_purge(void *);
154
155 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, hostcache,
156 CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
157 "TCP Host cache");
158
159 VNET_DEFINE(int, tcp_use_hostcache) = 1;
160 #define V_tcp_use_hostcache VNET(tcp_use_hostcache)
161 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, enable, CTLFLAG_VNET | CTLFLAG_RW,
162 &VNET_NAME(tcp_use_hostcache), 0,
163 "Enable the TCP hostcache");
164
165 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, cachelimit, CTLFLAG_VNET | CTLFLAG_RDTUN,
166 &VNET_NAME(tcp_hostcache.cache_limit), 0,
167 "Overall entry limit for hostcache");
168
169 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, hashsize, CTLFLAG_VNET | CTLFLAG_RDTUN,
170 &VNET_NAME(tcp_hostcache.hashsize), 0,
171 "Size of TCP hostcache hashtable");
172
173 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, bucketlimit,
174 CTLFLAG_VNET | CTLFLAG_RDTUN, &VNET_NAME(tcp_hostcache.bucket_limit), 0,
175 "Per-bucket hash limit for hostcache");
176
177 SYSCTL_UINT(_net_inet_tcp_hostcache, OID_AUTO, count, CTLFLAG_VNET | CTLFLAG_RD,
178 &VNET_NAME(tcp_hostcache.cache_count), 0,
179 "Current number of entries in hostcache");
180
181 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, expire, CTLFLAG_VNET | CTLFLAG_RW,
182 &VNET_NAME(tcp_hostcache.expire), 0,
183 "Expire time of TCP hostcache entries");
184
185 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, prune, CTLFLAG_VNET | CTLFLAG_RW,
186 &VNET_NAME(tcp_hostcache.prune), 0,
187 "Time between purge runs");
188
189 SYSCTL_INT(_net_inet_tcp_hostcache, OID_AUTO, purge, CTLFLAG_VNET | CTLFLAG_RW,
190 &VNET_NAME(tcp_hostcache.purgeall), 0,
191 "Expire all entries on next purge run");
192
193 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, list,
194 CTLFLAG_VNET | CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP | CTLFLAG_MPSAFE,
195 0, 0, sysctl_tcp_hc_list, "A",
196 "List of all hostcache entries");
197
198 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, histo,
199 CTLFLAG_VNET | CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_SKIP | CTLFLAG_MPSAFE,
200 0, 0, sysctl_tcp_hc_histo, "A",
201 "Print a histogram of hostcache hashbucket utilization");
202
203 SYSCTL_PROC(_net_inet_tcp_hostcache, OID_AUTO, purgenow,
204 CTLFLAG_VNET | CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
205 NULL, 0, sysctl_tcp_hc_purgenow, "I",
206 "Immediately purge all entries");
207
208 static MALLOC_DEFINE(M_HOSTCACHE, "hostcache", "TCP hostcache");
209
210 /* Use jenkins_hash32(), as in other parts of the tcp stack */
211 #define HOSTCACHE_HASH(inc) \
212 ((inc)->inc_flags & INC_ISIPV6) ? \
213 (jenkins_hash32((inc)->inc6_faddr.s6_addr32, 4, \
214 V_tcp_hostcache.hashsalt) & V_tcp_hostcache.hashmask) \
215 : \
216 (jenkins_hash32(&(inc)->inc_faddr.s_addr, 1, \
217 V_tcp_hostcache.hashsalt) & V_tcp_hostcache.hashmask)
218
219 #define THC_LOCK(h) mtx_lock(&(h)->hch_mtx)
220 #define THC_UNLOCK(h) mtx_unlock(&(h)->hch_mtx)
221
222 void
tcp_hc_init(void)223 tcp_hc_init(void)
224 {
225 u_int cache_limit;
226 int i;
227
228 /*
229 * Initialize hostcache structures.
230 */
231 atomic_store_int(&V_tcp_hostcache.cache_count, 0);
232 V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE;
233 V_tcp_hostcache.bucket_limit = TCP_HOSTCACHE_BUCKETLIMIT;
234 V_tcp_hostcache.expire = TCP_HOSTCACHE_EXPIRE;
235 V_tcp_hostcache.prune = TCP_HOSTCACHE_PRUNE;
236 V_tcp_hostcache.hashsalt = arc4random();
237
238 TUNABLE_INT_FETCH("net.inet.tcp.hostcache.hashsize",
239 &V_tcp_hostcache.hashsize);
240 if (!powerof2(V_tcp_hostcache.hashsize)) {
241 printf("WARNING: hostcache hash size is not a power of 2.\n");
242 V_tcp_hostcache.hashsize = TCP_HOSTCACHE_HASHSIZE; /* default */
243 }
244 V_tcp_hostcache.hashmask = V_tcp_hostcache.hashsize - 1;
245
246 TUNABLE_INT_FETCH("net.inet.tcp.hostcache.bucketlimit",
247 &V_tcp_hostcache.bucket_limit);
248
249 cache_limit = V_tcp_hostcache.hashsize * V_tcp_hostcache.bucket_limit;
250 V_tcp_hostcache.cache_limit = cache_limit;
251 TUNABLE_INT_FETCH("net.inet.tcp.hostcache.cachelimit",
252 &V_tcp_hostcache.cache_limit);
253 if (V_tcp_hostcache.cache_limit > cache_limit)
254 V_tcp_hostcache.cache_limit = cache_limit;
255
256 /*
257 * Allocate the hash table.
258 */
259 V_tcp_hostcache.hashbase = (struct hc_head *)
260 malloc(V_tcp_hostcache.hashsize * sizeof(struct hc_head),
261 M_HOSTCACHE, M_WAITOK | M_ZERO);
262
263 /*
264 * Initialize the hash buckets.
265 */
266 for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
267 CK_SLIST_INIT(&V_tcp_hostcache.hashbase[i].hch_bucket);
268 V_tcp_hostcache.hashbase[i].hch_length = 0;
269 mtx_init(&V_tcp_hostcache.hashbase[i].hch_mtx, "tcp_hc_entry",
270 NULL, MTX_DEF);
271 }
272
273 /*
274 * Allocate the hostcache entries.
275 */
276 V_tcp_hostcache.zone =
277 uma_zcreate("hostcache", sizeof(struct hc_metrics),
278 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_SMR);
279 uma_zone_set_max(V_tcp_hostcache.zone, V_tcp_hostcache.cache_limit);
280 V_tcp_hostcache.smr = uma_zone_get_smr(V_tcp_hostcache.zone);
281
282 /*
283 * Set up periodic cache cleanup.
284 */
285 callout_init(&V_tcp_hc_callout, 1);
286 callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
287 tcp_hc_purge, curvnet);
288 }
289
290 #ifdef VIMAGE
291 void
tcp_hc_destroy(void)292 tcp_hc_destroy(void)
293 {
294 int i;
295
296 callout_drain(&V_tcp_hc_callout);
297
298 /* Purge all hc entries. */
299 tcp_hc_purge_internal(1);
300
301 /* Free the uma zone and the allocated hash table. */
302 uma_zdestroy(V_tcp_hostcache.zone);
303
304 for (i = 0; i < V_tcp_hostcache.hashsize; i++)
305 mtx_destroy(&V_tcp_hostcache.hashbase[i].hch_mtx);
306 free(V_tcp_hostcache.hashbase, M_HOSTCACHE);
307 }
308 #endif
309
310 /*
311 * Internal function: compare cache entry to a connection.
312 */
313 static bool
tcp_hc_cmp(struct hc_metrics * hc_entry,const struct in_conninfo * inc)314 tcp_hc_cmp(struct hc_metrics *hc_entry, const struct in_conninfo *inc)
315 {
316
317 if (inc->inc_flags & INC_ISIPV6) {
318 /* XXX: check ip6_zoneid */
319 if (memcmp(&inc->inc6_faddr, &hc_entry->ip6,
320 sizeof(inc->inc6_faddr)) == 0)
321 return (true);
322 } else {
323 if (memcmp(&inc->inc_faddr, &hc_entry->ip4,
324 sizeof(inc->inc_faddr)) == 0)
325 return (true);
326 }
327
328 return (false);
329 }
330
331 /*
332 * Internal function: look up an entry in the hostcache for read.
333 * On success returns in SMR section.
334 */
335 static struct hc_metrics *
tcp_hc_lookup(const struct in_conninfo * inc)336 tcp_hc_lookup(const struct in_conninfo *inc)
337 {
338 struct hc_head *hc_head;
339 struct hc_metrics *hc_entry;
340
341 KASSERT(inc != NULL, ("%s: NULL in_conninfo", __func__));
342
343 hc_head = &V_tcp_hostcache.hashbase[HOSTCACHE_HASH(inc)];
344
345 /*
346 * Iterate through entries in bucket row looking for a match.
347 */
348 smr_enter(V_tcp_hostcache.smr);
349 CK_SLIST_FOREACH(hc_entry, &hc_head->hch_bucket, hc_q)
350 if (tcp_hc_cmp(hc_entry, inc))
351 break;
352
353 if (hc_entry != NULL) {
354 if (atomic_load_int(&hc_entry->hc_expire) !=
355 V_tcp_hostcache.expire)
356 atomic_store_int(&hc_entry->hc_expire,
357 V_tcp_hostcache.expire);
358 #ifdef TCP_HC_COUNTERS
359 hc_entry->hc_hits++;
360 #endif
361 } else
362 smr_exit(V_tcp_hostcache.smr);
363
364 return (hc_entry);
365 }
366
367 /*
368 * External function: look up an entry in the hostcache and fill out the
369 * supplied TCP metrics structure. Fills in NULL when no entry was found or
370 * a value is not set.
371 */
372 void
tcp_hc_get(const struct in_conninfo * inc,struct hc_metrics_lite * hc_metrics_lite)373 tcp_hc_get(const struct in_conninfo *inc,
374 struct hc_metrics_lite *hc_metrics_lite)
375 {
376 struct hc_metrics *hc_entry;
377
378 if (!V_tcp_use_hostcache) {
379 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
380 return;
381 }
382
383 /*
384 * Find the right bucket.
385 */
386 hc_entry = tcp_hc_lookup(inc);
387
388 /*
389 * If we don't have an existing object.
390 */
391 if (hc_entry == NULL) {
392 bzero(hc_metrics_lite, sizeof(*hc_metrics_lite));
393 return;
394 }
395
396 hc_metrics_lite->hc_mtu = atomic_load_32(&hc_entry->hc_mtu);
397 hc_metrics_lite->hc_ssthresh = atomic_load_32(&hc_entry->hc_ssthresh);
398 hc_metrics_lite->hc_rtt = atomic_load_32(&hc_entry->hc_rtt);
399 hc_metrics_lite->hc_rttvar = atomic_load_32(&hc_entry->hc_rttvar);
400 hc_metrics_lite->hc_cwnd = atomic_load_32(&hc_entry->hc_cwnd);
401 hc_metrics_lite->hc_sendpipe = atomic_load_32(&hc_entry->hc_sendpipe);
402 hc_metrics_lite->hc_recvpipe = atomic_load_32(&hc_entry->hc_recvpipe);
403
404 smr_exit(V_tcp_hostcache.smr);
405 }
406
407 /*
408 * External function: look up an entry in the hostcache and return the
409 * discovered path MTU. Returns 0 if no entry is found or value is not
410 * set.
411 */
412 uint32_t
tcp_hc_getmtu(const struct in_conninfo * inc)413 tcp_hc_getmtu(const struct in_conninfo *inc)
414 {
415 struct hc_metrics *hc_entry;
416 uint32_t mtu;
417
418 if (!V_tcp_use_hostcache)
419 return (0);
420
421 hc_entry = tcp_hc_lookup(inc);
422 if (hc_entry == NULL) {
423 return (0);
424 }
425
426 mtu = atomic_load_32(&hc_entry->hc_mtu);
427 smr_exit(V_tcp_hostcache.smr);
428
429 return (mtu);
430 }
431
432 /*
433 * External function: update the MTU value of an entry in the hostcache.
434 * Creates a new entry if none was found.
435 */
436 void
tcp_hc_updatemtu(const struct in_conninfo * inc,uint32_t mtu)437 tcp_hc_updatemtu(const struct in_conninfo *inc, uint32_t mtu)
438 {
439 struct hc_metrics_lite hcml = { .hc_mtu = mtu };
440
441 return (tcp_hc_update(inc, &hcml));
442 }
443
444 /*
445 * External function: update the TCP metrics of an entry in the hostcache.
446 * Creates a new entry if none was found.
447 */
448 void
tcp_hc_update(const struct in_conninfo * inc,struct hc_metrics_lite * hcml)449 tcp_hc_update(const struct in_conninfo *inc, struct hc_metrics_lite *hcml)
450 {
451 struct hc_head *hc_head;
452 struct hc_metrics *hc_entry, *hc_prev;
453 uint32_t v;
454 bool new;
455
456 if (!V_tcp_use_hostcache)
457 return;
458
459 hc_head = &V_tcp_hostcache.hashbase[HOSTCACHE_HASH(inc)];
460 hc_prev = NULL;
461
462 THC_LOCK(hc_head);
463 CK_SLIST_FOREACH(hc_entry, &hc_head->hch_bucket, hc_q) {
464 if (tcp_hc_cmp(hc_entry, inc))
465 break;
466 if (CK_SLIST_NEXT(hc_entry, hc_q) != NULL)
467 hc_prev = hc_entry;
468 }
469
470 if (hc_entry != NULL) {
471 if (atomic_load_int(&hc_entry->hc_expire) !=
472 V_tcp_hostcache.expire)
473 atomic_store_int(&hc_entry->hc_expire,
474 V_tcp_hostcache.expire);
475 #ifdef TCP_HC_COUNTERS
476 hc_entry->hc_updates++;
477 #endif
478 new = false;
479 } else {
480 /*
481 * Try to allocate a new entry. If the bucket limit is
482 * reached, delete the least-used element, located at the end
483 * of the CK_SLIST. During lookup we saved the pointer to
484 * the second to last element, in case if list has at least 2
485 * elements. This will allow to delete last element without
486 * extra traversal.
487 *
488 * Give up if the row is empty.
489 */
490 if (hc_head->hch_length >= V_tcp_hostcache.bucket_limit ||
491 atomic_load_int(&V_tcp_hostcache.cache_count) >=
492 V_tcp_hostcache.cache_limit) {
493 if (hc_prev != NULL) {
494 hc_entry = CK_SLIST_NEXT(hc_prev, hc_q);
495 KASSERT(CK_SLIST_NEXT(hc_entry, hc_q) == NULL,
496 ("%s: %p is not one to last",
497 __func__, hc_prev));
498 CK_SLIST_REMOVE_AFTER(hc_prev, hc_q);
499 } else if ((hc_entry =
500 CK_SLIST_FIRST(&hc_head->hch_bucket)) != NULL) {
501 KASSERT(CK_SLIST_NEXT(hc_entry, hc_q) == NULL,
502 ("%s: %p is not the only element",
503 __func__, hc_entry));
504 CK_SLIST_REMOVE_HEAD(&hc_head->hch_bucket,
505 hc_q);
506 } else {
507 THC_UNLOCK(hc_head);
508 return;
509 }
510 KASSERT(hc_head->hch_length > 0 &&
511 hc_head->hch_length <= V_tcp_hostcache.bucket_limit,
512 ("tcp_hostcache: bucket length violated at %p",
513 hc_head));
514 hc_head->hch_length--;
515 atomic_subtract_int(&V_tcp_hostcache.cache_count, 1);
516 TCPSTAT_INC(tcps_hc_bucketoverflow);
517 uma_zfree_smr(V_tcp_hostcache.zone, hc_entry);
518 }
519
520 /*
521 * Allocate a new entry, or balk if not possible.
522 */
523 hc_entry = uma_zalloc_smr(V_tcp_hostcache.zone, M_NOWAIT);
524 if (hc_entry == NULL) {
525 THC_UNLOCK(hc_head);
526 return;
527 }
528
529 /*
530 * Initialize basic information of hostcache entry.
531 */
532 bzero(hc_entry, sizeof(*hc_entry));
533 if (inc->inc_flags & INC_ISIPV6) {
534 hc_entry->ip6 = inc->inc6_faddr;
535 hc_entry->ip6_zoneid = inc->inc6_zoneid;
536 } else
537 hc_entry->ip4 = inc->inc_faddr;
538 hc_entry->hc_expire = V_tcp_hostcache.expire;
539 new = true;
540 }
541
542 /*
543 * Fill in data. Use atomics, since an existing entry is
544 * accessible by readers in SMR section.
545 */
546 if (hcml->hc_mtu != 0) {
547 atomic_store_32(&hc_entry->hc_mtu, hcml->hc_mtu);
548 }
549 if (hcml->hc_rtt != 0) {
550 if (hc_entry->hc_rtt == 0)
551 v = hcml->hc_rtt;
552 else
553 v = ((uint64_t)hc_entry->hc_rtt +
554 (uint64_t)hcml->hc_rtt) / 2;
555 atomic_store_32(&hc_entry->hc_rtt, v);
556 TCPSTAT_INC(tcps_cachedrtt);
557 }
558 if (hcml->hc_rttvar != 0) {
559 if (hc_entry->hc_rttvar == 0)
560 v = hcml->hc_rttvar;
561 else
562 v = ((uint64_t)hc_entry->hc_rttvar +
563 (uint64_t)hcml->hc_rttvar) / 2;
564 atomic_store_32(&hc_entry->hc_rttvar, v);
565 TCPSTAT_INC(tcps_cachedrttvar);
566 }
567 if (hcml->hc_ssthresh != 0) {
568 if (hc_entry->hc_ssthresh == 0)
569 v = hcml->hc_ssthresh;
570 else
571 v = (hc_entry->hc_ssthresh + hcml->hc_ssthresh) / 2;
572 atomic_store_32(&hc_entry->hc_ssthresh, v);
573 TCPSTAT_INC(tcps_cachedssthresh);
574 }
575 if (hcml->hc_cwnd != 0) {
576 if (hc_entry->hc_cwnd == 0)
577 v = hcml->hc_cwnd;
578 else
579 v = ((uint64_t)hc_entry->hc_cwnd +
580 (uint64_t)hcml->hc_cwnd) / 2;
581 atomic_store_32(&hc_entry->hc_cwnd, v);
582 /* TCPSTAT_INC(tcps_cachedcwnd); */
583 }
584 if (hcml->hc_sendpipe != 0) {
585 if (hc_entry->hc_sendpipe == 0)
586 v = hcml->hc_sendpipe;
587 else
588 v = ((uint64_t)hc_entry->hc_sendpipe +
589 (uint64_t)hcml->hc_sendpipe) /2;
590 atomic_store_32(&hc_entry->hc_sendpipe, v);
591 /* TCPSTAT_INC(tcps_cachedsendpipe); */
592 }
593 if (hcml->hc_recvpipe != 0) {
594 if (hc_entry->hc_recvpipe == 0)
595 v = hcml->hc_recvpipe;
596 else
597 v = ((uint64_t)hc_entry->hc_recvpipe +
598 (uint64_t)hcml->hc_recvpipe) /2;
599 atomic_store_32(&hc_entry->hc_recvpipe, v);
600 /* TCPSTAT_INC(tcps_cachedrecvpipe); */
601 }
602
603 /*
604 * Put it upfront.
605 */
606 if (new) {
607 CK_SLIST_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, hc_q);
608 hc_head->hch_length++;
609 KASSERT(hc_head->hch_length <= V_tcp_hostcache.bucket_limit,
610 ("tcp_hostcache: bucket length too high at %p", hc_head));
611 atomic_add_int(&V_tcp_hostcache.cache_count, 1);
612 TCPSTAT_INC(tcps_hc_added);
613 } else if (hc_entry != CK_SLIST_FIRST(&hc_head->hch_bucket)) {
614 KASSERT(CK_SLIST_NEXT(hc_prev, hc_q) == hc_entry,
615 ("%s: %p next is not %p", __func__, hc_prev, hc_entry));
616 CK_SLIST_REMOVE_AFTER(hc_prev, hc_q);
617 CK_SLIST_INSERT_HEAD(&hc_head->hch_bucket, hc_entry, hc_q);
618 }
619 THC_UNLOCK(hc_head);
620 }
621
622 /*
623 * Sysctl function: prints the list and values of all hostcache entries in
624 * unsorted order.
625 */
626 static int
sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS)627 sysctl_tcp_hc_list(SYSCTL_HANDLER_ARGS)
628 {
629 const int linesize = 128;
630 struct sbuf sb;
631 int i, error, len;
632 struct hc_metrics *hc_entry;
633 char ip4buf[INET_ADDRSTRLEN];
634 #ifdef INET6
635 char ip6buf[INET6_ADDRSTRLEN];
636 #endif
637
638 if (jailed_without_vnet(curthread->td_ucred) != 0)
639 return (EPERM);
640
641 /* Optimize Buffer length query by sbin/sysctl */
642 if (req->oldptr == NULL) {
643 len = (atomic_load_int(&V_tcp_hostcache.cache_count) + 1) *
644 linesize;
645 return (SYSCTL_OUT(req, NULL, len));
646 }
647
648 error = sysctl_wire_old_buffer(req, 0);
649 if (error != 0) {
650 return(error);
651 }
652
653 /* Use a buffer sized for one full bucket */
654 sbuf_new_for_sysctl(&sb, NULL, V_tcp_hostcache.bucket_limit *
655 linesize, req);
656
657 sbuf_printf(&sb,
658 "\nIP address MTU SSTRESH RTT RTTVAR "
659 " CWND SENDPIPE RECVPIPE "
660 #ifdef TCP_HC_COUNTERS
661 "HITS UPD "
662 #endif
663 "EXP\n");
664 sbuf_drain(&sb);
665
666 #define msec(u) (((u) + 500) / 1000)
667 for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
668 THC_LOCK(&V_tcp_hostcache.hashbase[i]);
669 CK_SLIST_FOREACH(hc_entry,
670 &V_tcp_hostcache.hashbase[i].hch_bucket, hc_q) {
671 sbuf_printf(&sb,
672 "%-15s %5u %8u %6lums %6lums %8u %8u %8u "
673 #ifdef TCP_HC_COUNTERS
674 "%4lu %4lu "
675 #endif
676 "%4i\n",
677 hc_entry->ip4.s_addr ?
678 inet_ntoa_r(hc_entry->ip4, ip4buf) :
679 #ifdef INET6
680 ip6_sprintf(ip6buf, &hc_entry->ip6),
681 #else
682 "IPv6?",
683 #endif
684 hc_entry->hc_mtu,
685 hc_entry->hc_ssthresh,
686 msec((u_long)hc_entry->hc_rtt *
687 (RTM_RTTUNIT / (hz * TCP_RTT_SCALE))),
688 msec((u_long)hc_entry->hc_rttvar *
689 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE))),
690 hc_entry->hc_cwnd,
691 hc_entry->hc_sendpipe,
692 hc_entry->hc_recvpipe,
693 #ifdef TCP_HC_COUNTERS
694 hc_entry->hc_hits,
695 hc_entry->hc_updates,
696 #endif
697 hc_entry->hc_expire);
698 }
699 THC_UNLOCK(&V_tcp_hostcache.hashbase[i]);
700 sbuf_drain(&sb);
701 }
702 #undef msec
703 error = sbuf_finish(&sb);
704 sbuf_delete(&sb);
705 return(error);
706 }
707
708 /*
709 * Sysctl function: prints a histogram of the hostcache hashbucket
710 * utilization.
711 */
712 static int
sysctl_tcp_hc_histo(SYSCTL_HANDLER_ARGS)713 sysctl_tcp_hc_histo(SYSCTL_HANDLER_ARGS)
714 {
715 const int linesize = 50;
716 struct sbuf sb;
717 int i, error;
718 int *histo;
719 u_int hch_length;
720
721 if (jailed_without_vnet(curthread->td_ucred) != 0)
722 return (EPERM);
723
724 histo = (int *)malloc(sizeof(int) * (V_tcp_hostcache.bucket_limit + 1),
725 M_TEMP, M_NOWAIT|M_ZERO);
726 if (histo == NULL)
727 return(ENOMEM);
728
729 for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
730 hch_length = V_tcp_hostcache.hashbase[i].hch_length;
731 KASSERT(hch_length <= V_tcp_hostcache.bucket_limit,
732 ("tcp_hostcache: bucket limit exceeded at %u: %u",
733 i, hch_length));
734 histo[hch_length]++;
735 }
736
737 /* Use a buffer for 16 lines */
738 sbuf_new_for_sysctl(&sb, NULL, 16 * linesize, req);
739
740 sbuf_printf(&sb, "\nLength\tCount\n");
741 for (i = 0; i <= V_tcp_hostcache.bucket_limit; i++) {
742 sbuf_printf(&sb, "%u\t%u\n", i, histo[i]);
743 }
744 error = sbuf_finish(&sb);
745 sbuf_delete(&sb);
746 free(histo, M_TEMP);
747 return(error);
748 }
749
750 /*
751 * Caller has to make sure the curvnet is set properly.
752 */
753 static void
tcp_hc_purge_internal(int all)754 tcp_hc_purge_internal(int all)
755 {
756 struct hc_head *head;
757 struct hc_metrics *hc_entry, *hc_next, *hc_prev;
758 int i;
759
760 for (i = 0; i < V_tcp_hostcache.hashsize; i++) {
761 head = &V_tcp_hostcache.hashbase[i];
762 hc_prev = NULL;
763 THC_LOCK(head);
764 CK_SLIST_FOREACH_SAFE(hc_entry, &head->hch_bucket, hc_q,
765 hc_next) {
766 KASSERT(head->hch_length > 0 && head->hch_length <=
767 V_tcp_hostcache.bucket_limit, ("tcp_hostcache: "
768 "bucket length out of range at %u: %u", i,
769 head->hch_length));
770 if (all ||
771 atomic_load_int(&hc_entry->hc_expire) <= 0) {
772 if (hc_prev != NULL) {
773 KASSERT(hc_entry ==
774 CK_SLIST_NEXT(hc_prev, hc_q),
775 ("%s: %p is not next to %p",
776 __func__, hc_entry, hc_prev));
777 CK_SLIST_REMOVE_AFTER(hc_prev, hc_q);
778 } else {
779 KASSERT(hc_entry ==
780 CK_SLIST_FIRST(&head->hch_bucket),
781 ("%s: %p is not first",
782 __func__, hc_entry));
783 CK_SLIST_REMOVE_HEAD(&head->hch_bucket,
784 hc_q);
785 }
786 uma_zfree_smr(V_tcp_hostcache.zone, hc_entry);
787 head->hch_length--;
788 atomic_subtract_int(&V_tcp_hostcache.cache_count, 1);
789 } else {
790 atomic_subtract_int(&hc_entry->hc_expire,
791 V_tcp_hostcache.prune);
792 hc_prev = hc_entry;
793 }
794 }
795 THC_UNLOCK(head);
796 }
797 }
798
799 /*
800 * Expire and purge (old|all) entries in the tcp_hostcache. Runs
801 * periodically from the callout.
802 */
803 static void
tcp_hc_purge(void * arg)804 tcp_hc_purge(void *arg)
805 {
806 CURVNET_SET((struct vnet *) arg);
807 int all = 0;
808
809 if (V_tcp_hostcache.purgeall) {
810 if (V_tcp_hostcache.purgeall == 2)
811 V_tcp_hostcache.hashsalt = arc4random();
812 all = 1;
813 V_tcp_hostcache.purgeall = 0;
814 }
815
816 tcp_hc_purge_internal(all);
817
818 callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
819 tcp_hc_purge, arg);
820 CURVNET_RESTORE();
821 }
822
823 /*
824 * Expire and purge all entries in hostcache immediately.
825 */
826 static int
sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS)827 sysctl_tcp_hc_purgenow(SYSCTL_HANDLER_ARGS)
828 {
829 int error, val;
830
831 val = 0;
832 error = sysctl_handle_int(oidp, &val, 0, req);
833 if (error || !req->newptr)
834 return (error);
835
836 if (val == 2)
837 V_tcp_hostcache.hashsalt = arc4random();
838 tcp_hc_purge_internal(1);
839
840 callout_reset(&V_tcp_hc_callout, V_tcp_hostcache.prune * hz,
841 tcp_hc_purge, curvnet);
842
843 return (0);
844 }
845