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TOMOYO Linux Cross Reference
Linux/net/ipv4/tcp_metrics.c

Version: ~ [ linux-5.8 ] ~ [ linux-5.7.14 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.57 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.138 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.193 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.232 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.232 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.85 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  1 // SPDX-License-Identifier: GPL-2.0
  2 #include <linux/rcupdate.h>
  3 #include <linux/spinlock.h>
  4 #include <linux/jiffies.h>
  5 #include <linux/module.h>
  6 #include <linux/cache.h>
  7 #include <linux/slab.h>
  8 #include <linux/init.h>
  9 #include <linux/tcp.h>
 10 #include <linux/hash.h>
 11 #include <linux/tcp_metrics.h>
 12 #include <linux/vmalloc.h>
 13 
 14 #include <net/inet_connection_sock.h>
 15 #include <net/net_namespace.h>
 16 #include <net/request_sock.h>
 17 #include <net/inetpeer.h>
 18 #include <net/sock.h>
 19 #include <net/ipv6.h>
 20 #include <net/dst.h>
 21 #include <net/tcp.h>
 22 #include <net/genetlink.h>
 23 
 24 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
 25                                                    const struct inetpeer_addr *daddr,
 26                                                    struct net *net, unsigned int hash);
 27 
 28 struct tcp_fastopen_metrics {
 29         u16     mss;
 30         u16     syn_loss:10,            /* Recurring Fast Open SYN losses */
 31                 try_exp:2;              /* Request w/ exp. option (once) */
 32         unsigned long   last_syn_loss;  /* Last Fast Open SYN loss */
 33         struct  tcp_fastopen_cookie     cookie;
 34 };
 35 
 36 /* TCP_METRIC_MAX includes 2 extra fields for userspace compatibility
 37  * Kernel only stores RTT and RTTVAR in usec resolution
 38  */
 39 #define TCP_METRIC_MAX_KERNEL (TCP_METRIC_MAX - 2)
 40 
 41 struct tcp_metrics_block {
 42         struct tcp_metrics_block __rcu  *tcpm_next;
 43         possible_net_t                  tcpm_net;
 44         struct inetpeer_addr            tcpm_saddr;
 45         struct inetpeer_addr            tcpm_daddr;
 46         unsigned long                   tcpm_stamp;
 47         u32                             tcpm_lock;
 48         u32                             tcpm_vals[TCP_METRIC_MAX_KERNEL + 1];
 49         struct tcp_fastopen_metrics     tcpm_fastopen;
 50 
 51         struct rcu_head                 rcu_head;
 52 };
 53 
 54 static inline struct net *tm_net(struct tcp_metrics_block *tm)
 55 {
 56         return read_pnet(&tm->tcpm_net);
 57 }
 58 
 59 static bool tcp_metric_locked(struct tcp_metrics_block *tm,
 60                               enum tcp_metric_index idx)
 61 {
 62         return tm->tcpm_lock & (1 << idx);
 63 }
 64 
 65 static u32 tcp_metric_get(struct tcp_metrics_block *tm,
 66                           enum tcp_metric_index idx)
 67 {
 68         return tm->tcpm_vals[idx];
 69 }
 70 
 71 static void tcp_metric_set(struct tcp_metrics_block *tm,
 72                            enum tcp_metric_index idx,
 73                            u32 val)
 74 {
 75         tm->tcpm_vals[idx] = val;
 76 }
 77 
 78 static bool addr_same(const struct inetpeer_addr *a,
 79                       const struct inetpeer_addr *b)
 80 {
 81         return inetpeer_addr_cmp(a, b) == 0;
 82 }
 83 
 84 struct tcpm_hash_bucket {
 85         struct tcp_metrics_block __rcu  *chain;
 86 };
 87 
 88 static struct tcpm_hash_bucket  *tcp_metrics_hash __read_mostly;
 89 static unsigned int             tcp_metrics_hash_log __read_mostly;
 90 
 91 static DEFINE_SPINLOCK(tcp_metrics_lock);
 92 
 93 static void tcpm_suck_dst(struct tcp_metrics_block *tm,
 94                           const struct dst_entry *dst,
 95                           bool fastopen_clear)
 96 {
 97         u32 msval;
 98         u32 val;
 99 
100         tm->tcpm_stamp = jiffies;
101 
102         val = 0;
103         if (dst_metric_locked(dst, RTAX_RTT))
104                 val |= 1 << TCP_METRIC_RTT;
105         if (dst_metric_locked(dst, RTAX_RTTVAR))
106                 val |= 1 << TCP_METRIC_RTTVAR;
107         if (dst_metric_locked(dst, RTAX_SSTHRESH))
108                 val |= 1 << TCP_METRIC_SSTHRESH;
109         if (dst_metric_locked(dst, RTAX_CWND))
110                 val |= 1 << TCP_METRIC_CWND;
111         if (dst_metric_locked(dst, RTAX_REORDERING))
112                 val |= 1 << TCP_METRIC_REORDERING;
113         tm->tcpm_lock = val;
114 
115         msval = dst_metric_raw(dst, RTAX_RTT);
116         tm->tcpm_vals[TCP_METRIC_RTT] = msval * USEC_PER_MSEC;
117 
118         msval = dst_metric_raw(dst, RTAX_RTTVAR);
119         tm->tcpm_vals[TCP_METRIC_RTTVAR] = msval * USEC_PER_MSEC;
120         tm->tcpm_vals[TCP_METRIC_SSTHRESH] = dst_metric_raw(dst, RTAX_SSTHRESH);
121         tm->tcpm_vals[TCP_METRIC_CWND] = dst_metric_raw(dst, RTAX_CWND);
122         tm->tcpm_vals[TCP_METRIC_REORDERING] = dst_metric_raw(dst, RTAX_REORDERING);
123         if (fastopen_clear) {
124                 tm->tcpm_fastopen.mss = 0;
125                 tm->tcpm_fastopen.syn_loss = 0;
126                 tm->tcpm_fastopen.try_exp = 0;
127                 tm->tcpm_fastopen.cookie.exp = false;
128                 tm->tcpm_fastopen.cookie.len = 0;
129         }
130 }
131 
132 #define TCP_METRICS_TIMEOUT             (60 * 60 * HZ)
133 
134 static void tcpm_check_stamp(struct tcp_metrics_block *tm, struct dst_entry *dst)
135 {
136         if (tm && unlikely(time_after(jiffies, tm->tcpm_stamp + TCP_METRICS_TIMEOUT)))
137                 tcpm_suck_dst(tm, dst, false);
138 }
139 
140 #define TCP_METRICS_RECLAIM_DEPTH       5
141 #define TCP_METRICS_RECLAIM_PTR         (struct tcp_metrics_block *) 0x1UL
142 
143 #define deref_locked(p) \
144         rcu_dereference_protected(p, lockdep_is_held(&tcp_metrics_lock))
145 
146 static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
147                                           struct inetpeer_addr *saddr,
148                                           struct inetpeer_addr *daddr,
149                                           unsigned int hash)
150 {
151         struct tcp_metrics_block *tm;
152         struct net *net;
153         bool reclaim = false;
154 
155         spin_lock_bh(&tcp_metrics_lock);
156         net = dev_net(dst->dev);
157 
158         /* While waiting for the spin-lock the cache might have been populated
159          * with this entry and so we have to check again.
160          */
161         tm = __tcp_get_metrics(saddr, daddr, net, hash);
162         if (tm == TCP_METRICS_RECLAIM_PTR) {
163                 reclaim = true;
164                 tm = NULL;
165         }
166         if (tm) {
167                 tcpm_check_stamp(tm, dst);
168                 goto out_unlock;
169         }
170 
171         if (unlikely(reclaim)) {
172                 struct tcp_metrics_block *oldest;
173 
174                 oldest = deref_locked(tcp_metrics_hash[hash].chain);
175                 for (tm = deref_locked(oldest->tcpm_next); tm;
176                      tm = deref_locked(tm->tcpm_next)) {
177                         if (time_before(tm->tcpm_stamp, oldest->tcpm_stamp))
178                                 oldest = tm;
179                 }
180                 tm = oldest;
181         } else {
182                 tm = kmalloc(sizeof(*tm), GFP_ATOMIC);
183                 if (!tm)
184                         goto out_unlock;
185         }
186         write_pnet(&tm->tcpm_net, net);
187         tm->tcpm_saddr = *saddr;
188         tm->tcpm_daddr = *daddr;
189 
190         tcpm_suck_dst(tm, dst, true);
191 
192         if (likely(!reclaim)) {
193                 tm->tcpm_next = tcp_metrics_hash[hash].chain;
194                 rcu_assign_pointer(tcp_metrics_hash[hash].chain, tm);
195         }
196 
197 out_unlock:
198         spin_unlock_bh(&tcp_metrics_lock);
199         return tm;
200 }
201 
202 static struct tcp_metrics_block *tcp_get_encode(struct tcp_metrics_block *tm, int depth)
203 {
204         if (tm)
205                 return tm;
206         if (depth > TCP_METRICS_RECLAIM_DEPTH)
207                 return TCP_METRICS_RECLAIM_PTR;
208         return NULL;
209 }
210 
211 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
212                                                    const struct inetpeer_addr *daddr,
213                                                    struct net *net, unsigned int hash)
214 {
215         struct tcp_metrics_block *tm;
216         int depth = 0;
217 
218         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
219              tm = rcu_dereference(tm->tcpm_next)) {
220                 if (addr_same(&tm->tcpm_saddr, saddr) &&
221                     addr_same(&tm->tcpm_daddr, daddr) &&
222                     net_eq(tm_net(tm), net))
223                         break;
224                 depth++;
225         }
226         return tcp_get_encode(tm, depth);
227 }
228 
229 static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
230                                                        struct dst_entry *dst)
231 {
232         struct tcp_metrics_block *tm;
233         struct inetpeer_addr saddr, daddr;
234         unsigned int hash;
235         struct net *net;
236 
237         saddr.family = req->rsk_ops->family;
238         daddr.family = req->rsk_ops->family;
239         switch (daddr.family) {
240         case AF_INET:
241                 inetpeer_set_addr_v4(&saddr, inet_rsk(req)->ir_loc_addr);
242                 inetpeer_set_addr_v4(&daddr, inet_rsk(req)->ir_rmt_addr);
243                 hash = ipv4_addr_hash(inet_rsk(req)->ir_rmt_addr);
244                 break;
245 #if IS_ENABLED(CONFIG_IPV6)
246         case AF_INET6:
247                 inetpeer_set_addr_v6(&saddr, &inet_rsk(req)->ir_v6_loc_addr);
248                 inetpeer_set_addr_v6(&daddr, &inet_rsk(req)->ir_v6_rmt_addr);
249                 hash = ipv6_addr_hash(&inet_rsk(req)->ir_v6_rmt_addr);
250                 break;
251 #endif
252         default:
253                 return NULL;
254         }
255 
256         net = dev_net(dst->dev);
257         hash ^= net_hash_mix(net);
258         hash = hash_32(hash, tcp_metrics_hash_log);
259 
260         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
261              tm = rcu_dereference(tm->tcpm_next)) {
262                 if (addr_same(&tm->tcpm_saddr, &saddr) &&
263                     addr_same(&tm->tcpm_daddr, &daddr) &&
264                     net_eq(tm_net(tm), net))
265                         break;
266         }
267         tcpm_check_stamp(tm, dst);
268         return tm;
269 }
270 
271 static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
272                                                  struct dst_entry *dst,
273                                                  bool create)
274 {
275         struct tcp_metrics_block *tm;
276         struct inetpeer_addr saddr, daddr;
277         unsigned int hash;
278         struct net *net;
279 
280         if (sk->sk_family == AF_INET) {
281                 inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
282                 inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
283                 hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
284         }
285 #if IS_ENABLED(CONFIG_IPV6)
286         else if (sk->sk_family == AF_INET6) {
287                 if (ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
288                         inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
289                         inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
290                         hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
291                 } else {
292                         inetpeer_set_addr_v6(&saddr, &sk->sk_v6_rcv_saddr);
293                         inetpeer_set_addr_v6(&daddr, &sk->sk_v6_daddr);
294                         hash = ipv6_addr_hash(&sk->sk_v6_daddr);
295                 }
296         }
297 #endif
298         else
299                 return NULL;
300 
301         net = dev_net(dst->dev);
302         hash ^= net_hash_mix(net);
303         hash = hash_32(hash, tcp_metrics_hash_log);
304 
305         tm = __tcp_get_metrics(&saddr, &daddr, net, hash);
306         if (tm == TCP_METRICS_RECLAIM_PTR)
307                 tm = NULL;
308         if (!tm && create)
309                 tm = tcpm_new(dst, &saddr, &daddr, hash);
310         else
311                 tcpm_check_stamp(tm, dst);
312 
313         return tm;
314 }
315 
316 /* Save metrics learned by this TCP session.  This function is called
317  * only, when TCP finishes successfully i.e. when it enters TIME-WAIT
318  * or goes from LAST-ACK to CLOSE.
319  */
320 void tcp_update_metrics(struct sock *sk)
321 {
322         const struct inet_connection_sock *icsk = inet_csk(sk);
323         struct dst_entry *dst = __sk_dst_get(sk);
324         struct tcp_sock *tp = tcp_sk(sk);
325         struct net *net = sock_net(sk);
326         struct tcp_metrics_block *tm;
327         unsigned long rtt;
328         u32 val;
329         int m;
330 
331         sk_dst_confirm(sk);
332         if (net->ipv4.sysctl_tcp_nometrics_save || !dst)
333                 return;
334 
335         rcu_read_lock();
336         if (icsk->icsk_backoff || !tp->srtt_us) {
337                 /* This session failed to estimate rtt. Why?
338                  * Probably, no packets returned in time.  Reset our
339                  * results.
340                  */
341                 tm = tcp_get_metrics(sk, dst, false);
342                 if (tm && !tcp_metric_locked(tm, TCP_METRIC_RTT))
343                         tcp_metric_set(tm, TCP_METRIC_RTT, 0);
344                 goto out_unlock;
345         } else
346                 tm = tcp_get_metrics(sk, dst, true);
347 
348         if (!tm)
349                 goto out_unlock;
350 
351         rtt = tcp_metric_get(tm, TCP_METRIC_RTT);
352         m = rtt - tp->srtt_us;
353 
354         /* If newly calculated rtt larger than stored one, store new
355          * one. Otherwise, use EWMA. Remember, rtt overestimation is
356          * always better than underestimation.
357          */
358         if (!tcp_metric_locked(tm, TCP_METRIC_RTT)) {
359                 if (m <= 0)
360                         rtt = tp->srtt_us;
361                 else
362                         rtt -= (m >> 3);
363                 tcp_metric_set(tm, TCP_METRIC_RTT, rtt);
364         }
365 
366         if (!tcp_metric_locked(tm, TCP_METRIC_RTTVAR)) {
367                 unsigned long var;
368 
369                 if (m < 0)
370                         m = -m;
371 
372                 /* Scale deviation to rttvar fixed point */
373                 m >>= 1;
374                 if (m < tp->mdev_us)
375                         m = tp->mdev_us;
376 
377                 var = tcp_metric_get(tm, TCP_METRIC_RTTVAR);
378                 if (m >= var)
379                         var = m;
380                 else
381                         var -= (var - m) >> 2;
382 
383                 tcp_metric_set(tm, TCP_METRIC_RTTVAR, var);
384         }
385 
386         if (tcp_in_initial_slowstart(tp)) {
387                 /* Slow start still did not finish. */
388                 if (!net->ipv4.sysctl_tcp_no_ssthresh_metrics_save &&
389                     !tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
390                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
391                         if (val && (tp->snd_cwnd >> 1) > val)
392                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
393                                                tp->snd_cwnd >> 1);
394                 }
395                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
396                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
397                         if (tp->snd_cwnd > val)
398                                 tcp_metric_set(tm, TCP_METRIC_CWND,
399                                                tp->snd_cwnd);
400                 }
401         } else if (!tcp_in_slow_start(tp) &&
402                    icsk->icsk_ca_state == TCP_CA_Open) {
403                 /* Cong. avoidance phase, cwnd is reliable. */
404                 if (!net->ipv4.sysctl_tcp_no_ssthresh_metrics_save &&
405                     !tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
406                         tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
407                                        max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
408                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
409                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
410                         tcp_metric_set(tm, TCP_METRIC_CWND, (val + tp->snd_cwnd) >> 1);
411                 }
412         } else {
413                 /* Else slow start did not finish, cwnd is non-sense,
414                  * ssthresh may be also invalid.
415                  */
416                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
417                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
418                         tcp_metric_set(tm, TCP_METRIC_CWND,
419                                        (val + tp->snd_ssthresh) >> 1);
420                 }
421                 if (!net->ipv4.sysctl_tcp_no_ssthresh_metrics_save &&
422                     !tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
423                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
424                         if (val && tp->snd_ssthresh > val)
425                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
426                                                tp->snd_ssthresh);
427                 }
428                 if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {
429                         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
430                         if (val < tp->reordering &&
431                             tp->reordering != net->ipv4.sysctl_tcp_reordering)
432                                 tcp_metric_set(tm, TCP_METRIC_REORDERING,
433                                                tp->reordering);
434                 }
435         }
436         tm->tcpm_stamp = jiffies;
437 out_unlock:
438         rcu_read_unlock();
439 }
440 
441 /* Initialize metrics on socket. */
442 
443 void tcp_init_metrics(struct sock *sk)
444 {
445         struct dst_entry *dst = __sk_dst_get(sk);
446         struct tcp_sock *tp = tcp_sk(sk);
447         struct net *net = sock_net(sk);
448         struct tcp_metrics_block *tm;
449         u32 val, crtt = 0; /* cached RTT scaled by 8 */
450 
451         sk_dst_confirm(sk);
452         if (!dst)
453                 goto reset;
454 
455         rcu_read_lock();
456         tm = tcp_get_metrics(sk, dst, true);
457         if (!tm) {
458                 rcu_read_unlock();
459                 goto reset;
460         }
461 
462         if (tcp_metric_locked(tm, TCP_METRIC_CWND))
463                 tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
464 
465         val = net->ipv4.sysctl_tcp_no_ssthresh_metrics_save ?
466               0 : tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
467         if (val) {
468                 tp->snd_ssthresh = val;
469                 if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
470                         tp->snd_ssthresh = tp->snd_cwnd_clamp;
471         } else {
472                 /* ssthresh may have been reduced unnecessarily during.
473                  * 3WHS. Restore it back to its initial default.
474                  */
475                 tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
476         }
477         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
478         if (val && tp->reordering != val)
479                 tp->reordering = val;
480 
481         crtt = tcp_metric_get(tm, TCP_METRIC_RTT);
482         rcu_read_unlock();
483 reset:
484         /* The initial RTT measurement from the SYN/SYN-ACK is not ideal
485          * to seed the RTO for later data packets because SYN packets are
486          * small. Use the per-dst cached values to seed the RTO but keep
487          * the RTT estimator variables intact (e.g., srtt, mdev, rttvar).
488          * Later the RTO will be updated immediately upon obtaining the first
489          * data RTT sample (tcp_rtt_estimator()). Hence the cached RTT only
490          * influences the first RTO but not later RTT estimation.
491          *
492          * But if RTT is not available from the SYN (due to retransmits or
493          * syn cookies) or the cache, force a conservative 3secs timeout.
494          *
495          * A bit of theory. RTT is time passed after "normal" sized packet
496          * is sent until it is ACKed. In normal circumstances sending small
497          * packets force peer to delay ACKs and calculation is correct too.
498          * The algorithm is adaptive and, provided we follow specs, it
499          * NEVER underestimate RTT. BUT! If peer tries to make some clever
500          * tricks sort of "quick acks" for time long enough to decrease RTT
501          * to low value, and then abruptly stops to do it and starts to delay
502          * ACKs, wait for troubles.
503          */
504         if (crtt > tp->srtt_us) {
505                 /* Set RTO like tcp_rtt_estimator(), but from cached RTT. */
506                 crtt /= 8 * USEC_PER_SEC / HZ;
507                 inet_csk(sk)->icsk_rto = crtt + max(2 * crtt, tcp_rto_min(sk));
508         } else if (tp->srtt_us == 0) {
509                 /* RFC6298: 5.7 We've failed to get a valid RTT sample from
510                  * 3WHS. This is most likely due to retransmission,
511                  * including spurious one. Reset the RTO back to 3secs
512                  * from the more aggressive 1sec to avoid more spurious
513                  * retransmission.
514                  */
515                 tp->rttvar_us = jiffies_to_usecs(TCP_TIMEOUT_FALLBACK);
516                 tp->mdev_us = tp->mdev_max_us = tp->rttvar_us;
517 
518                 inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
519         }
520 }
521 
522 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst)
523 {
524         struct tcp_metrics_block *tm;
525         bool ret;
526 
527         if (!dst)
528                 return false;
529 
530         rcu_read_lock();
531         tm = __tcp_get_metrics_req(req, dst);
532         if (tm && tcp_metric_get(tm, TCP_METRIC_RTT))
533                 ret = true;
534         else
535                 ret = false;
536         rcu_read_unlock();
537 
538         return ret;
539 }
540 
541 static DEFINE_SEQLOCK(fastopen_seqlock);
542 
543 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
544                             struct tcp_fastopen_cookie *cookie)
545 {
546         struct tcp_metrics_block *tm;
547 
548         rcu_read_lock();
549         tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
550         if (tm) {
551                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
552                 unsigned int seq;
553 
554                 do {
555                         seq = read_seqbegin(&fastopen_seqlock);
556                         if (tfom->mss)
557                                 *mss = tfom->mss;
558                         *cookie = tfom->cookie;
559                         if (cookie->len <= 0 && tfom->try_exp == 1)
560                                 cookie->exp = true;
561                 } while (read_seqretry(&fastopen_seqlock, seq));
562         }
563         rcu_read_unlock();
564 }
565 
566 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
567                             struct tcp_fastopen_cookie *cookie, bool syn_lost,
568                             u16 try_exp)
569 {
570         struct dst_entry *dst = __sk_dst_get(sk);
571         struct tcp_metrics_block *tm;
572 
573         if (!dst)
574                 return;
575         rcu_read_lock();
576         tm = tcp_get_metrics(sk, dst, true);
577         if (tm) {
578                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
579 
580                 write_seqlock_bh(&fastopen_seqlock);
581                 if (mss)
582                         tfom->mss = mss;
583                 if (cookie && cookie->len > 0)
584                         tfom->cookie = *cookie;
585                 else if (try_exp > tfom->try_exp &&
586                          tfom->cookie.len <= 0 && !tfom->cookie.exp)
587                         tfom->try_exp = try_exp;
588                 if (syn_lost) {
589                         ++tfom->syn_loss;
590                         tfom->last_syn_loss = jiffies;
591                 } else
592                         tfom->syn_loss = 0;
593                 write_sequnlock_bh(&fastopen_seqlock);
594         }
595         rcu_read_unlock();
596 }
597 
598 static struct genl_family tcp_metrics_nl_family;
599 
600 static const struct nla_policy tcp_metrics_nl_policy[TCP_METRICS_ATTR_MAX + 1] = {
601         [TCP_METRICS_ATTR_ADDR_IPV4]    = { .type = NLA_U32, },
602         [TCP_METRICS_ATTR_ADDR_IPV6]    = { .type = NLA_BINARY,
603                                             .len = sizeof(struct in6_addr), },
604         /* Following attributes are not received for GET/DEL,
605          * we keep them for reference
606          */
607 #if 0
608         [TCP_METRICS_ATTR_AGE]          = { .type = NLA_MSECS, },
609         [TCP_METRICS_ATTR_TW_TSVAL]     = { .type = NLA_U32, },
610         [TCP_METRICS_ATTR_TW_TS_STAMP]  = { .type = NLA_S32, },
611         [TCP_METRICS_ATTR_VALS]         = { .type = NLA_NESTED, },
612         [TCP_METRICS_ATTR_FOPEN_MSS]    = { .type = NLA_U16, },
613         [TCP_METRICS_ATTR_FOPEN_SYN_DROPS]      = { .type = NLA_U16, },
614         [TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS]    = { .type = NLA_MSECS, },
615         [TCP_METRICS_ATTR_FOPEN_COOKIE] = { .type = NLA_BINARY,
616                                             .len = TCP_FASTOPEN_COOKIE_MAX, },
617 #endif
618 };
619 
620 /* Add attributes, caller cancels its header on failure */
621 static int tcp_metrics_fill_info(struct sk_buff *msg,
622                                  struct tcp_metrics_block *tm)
623 {
624         struct nlattr *nest;
625         int i;
626 
627         switch (tm->tcpm_daddr.family) {
628         case AF_INET:
629                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_ADDR_IPV4,
630                                     inetpeer_get_addr_v4(&tm->tcpm_daddr)) < 0)
631                         goto nla_put_failure;
632                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_SADDR_IPV4,
633                                     inetpeer_get_addr_v4(&tm->tcpm_saddr)) < 0)
634                         goto nla_put_failure;
635                 break;
636         case AF_INET6:
637                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_ADDR_IPV6,
638                                      inetpeer_get_addr_v6(&tm->tcpm_daddr)) < 0)
639                         goto nla_put_failure;
640                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_SADDR_IPV6,
641                                      inetpeer_get_addr_v6(&tm->tcpm_saddr)) < 0)
642                         goto nla_put_failure;
643                 break;
644         default:
645                 return -EAFNOSUPPORT;
646         }
647 
648         if (nla_put_msecs(msg, TCP_METRICS_ATTR_AGE,
649                           jiffies - tm->tcpm_stamp,
650                           TCP_METRICS_ATTR_PAD) < 0)
651                 goto nla_put_failure;
652 
653         {
654                 int n = 0;
655 
656                 nest = nla_nest_start_noflag(msg, TCP_METRICS_ATTR_VALS);
657                 if (!nest)
658                         goto nla_put_failure;
659                 for (i = 0; i < TCP_METRIC_MAX_KERNEL + 1; i++) {
660                         u32 val = tm->tcpm_vals[i];
661 
662                         if (!val)
663                                 continue;
664                         if (i == TCP_METRIC_RTT) {
665                                 if (nla_put_u32(msg, TCP_METRIC_RTT_US + 1,
666                                                 val) < 0)
667                                         goto nla_put_failure;
668                                 n++;
669                                 val = max(val / 1000, 1U);
670                         }
671                         if (i == TCP_METRIC_RTTVAR) {
672                                 if (nla_put_u32(msg, TCP_METRIC_RTTVAR_US + 1,
673                                                 val) < 0)
674                                         goto nla_put_failure;
675                                 n++;
676                                 val = max(val / 1000, 1U);
677                         }
678                         if (nla_put_u32(msg, i + 1, val) < 0)
679                                 goto nla_put_failure;
680                         n++;
681                 }
682                 if (n)
683                         nla_nest_end(msg, nest);
684                 else
685                         nla_nest_cancel(msg, nest);
686         }
687 
688         {
689                 struct tcp_fastopen_metrics tfom_copy[1], *tfom;
690                 unsigned int seq;
691 
692                 do {
693                         seq = read_seqbegin(&fastopen_seqlock);
694                         tfom_copy[0] = tm->tcpm_fastopen;
695                 } while (read_seqretry(&fastopen_seqlock, seq));
696 
697                 tfom = tfom_copy;
698                 if (tfom->mss &&
699                     nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_MSS,
700                                 tfom->mss) < 0)
701                         goto nla_put_failure;
702                 if (tfom->syn_loss &&
703                     (nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROPS,
704                                 tfom->syn_loss) < 0 ||
705                      nla_put_msecs(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS,
706                                 jiffies - tfom->last_syn_loss,
707                                 TCP_METRICS_ATTR_PAD) < 0))
708                         goto nla_put_failure;
709                 if (tfom->cookie.len > 0 &&
710                     nla_put(msg, TCP_METRICS_ATTR_FOPEN_COOKIE,
711                             tfom->cookie.len, tfom->cookie.val) < 0)
712                         goto nla_put_failure;
713         }
714 
715         return 0;
716 
717 nla_put_failure:
718         return -EMSGSIZE;
719 }
720 
721 static int tcp_metrics_dump_info(struct sk_buff *skb,
722                                  struct netlink_callback *cb,
723                                  struct tcp_metrics_block *tm)
724 {
725         void *hdr;
726 
727         hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
728                           &tcp_metrics_nl_family, NLM_F_MULTI,
729                           TCP_METRICS_CMD_GET);
730         if (!hdr)
731                 return -EMSGSIZE;
732 
733         if (tcp_metrics_fill_info(skb, tm) < 0)
734                 goto nla_put_failure;
735 
736         genlmsg_end(skb, hdr);
737         return 0;
738 
739 nla_put_failure:
740         genlmsg_cancel(skb, hdr);
741         return -EMSGSIZE;
742 }
743 
744 static int tcp_metrics_nl_dump(struct sk_buff *skb,
745                                struct netlink_callback *cb)
746 {
747         struct net *net = sock_net(skb->sk);
748         unsigned int max_rows = 1U << tcp_metrics_hash_log;
749         unsigned int row, s_row = cb->args[0];
750         int s_col = cb->args[1], col = s_col;
751 
752         for (row = s_row; row < max_rows; row++, s_col = 0) {
753                 struct tcp_metrics_block *tm;
754                 struct tcpm_hash_bucket *hb = tcp_metrics_hash + row;
755 
756                 rcu_read_lock();
757                 for (col = 0, tm = rcu_dereference(hb->chain); tm;
758                      tm = rcu_dereference(tm->tcpm_next), col++) {
759                         if (!net_eq(tm_net(tm), net))
760                                 continue;
761                         if (col < s_col)
762                                 continue;
763                         if (tcp_metrics_dump_info(skb, cb, tm) < 0) {
764                                 rcu_read_unlock();
765                                 goto done;
766                         }
767                 }
768                 rcu_read_unlock();
769         }
770 
771 done:
772         cb->args[0] = row;
773         cb->args[1] = col;
774         return skb->len;
775 }
776 
777 static int __parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
778                            unsigned int *hash, int optional, int v4, int v6)
779 {
780         struct nlattr *a;
781 
782         a = info->attrs[v4];
783         if (a) {
784                 inetpeer_set_addr_v4(addr, nla_get_in_addr(a));
785                 if (hash)
786                         *hash = ipv4_addr_hash(inetpeer_get_addr_v4(addr));
787                 return 0;
788         }
789         a = info->attrs[v6];
790         if (a) {
791                 struct in6_addr in6;
792 
793                 if (nla_len(a) != sizeof(struct in6_addr))
794                         return -EINVAL;
795                 in6 = nla_get_in6_addr(a);
796                 inetpeer_set_addr_v6(addr, &in6);
797                 if (hash)
798                         *hash = ipv6_addr_hash(inetpeer_get_addr_v6(addr));
799                 return 0;
800         }
801         return optional ? 1 : -EAFNOSUPPORT;
802 }
803 
804 static int parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
805                          unsigned int *hash, int optional)
806 {
807         return __parse_nl_addr(info, addr, hash, optional,
808                                TCP_METRICS_ATTR_ADDR_IPV4,
809                                TCP_METRICS_ATTR_ADDR_IPV6);
810 }
811 
812 static int parse_nl_saddr(struct genl_info *info, struct inetpeer_addr *addr)
813 {
814         return __parse_nl_addr(info, addr, NULL, 0,
815                                TCP_METRICS_ATTR_SADDR_IPV4,
816                                TCP_METRICS_ATTR_SADDR_IPV6);
817 }
818 
819 static int tcp_metrics_nl_cmd_get(struct sk_buff *skb, struct genl_info *info)
820 {
821         struct tcp_metrics_block *tm;
822         struct inetpeer_addr saddr, daddr;
823         unsigned int hash;
824         struct sk_buff *msg;
825         struct net *net = genl_info_net(info);
826         void *reply;
827         int ret;
828         bool src = true;
829 
830         ret = parse_nl_addr(info, &daddr, &hash, 0);
831         if (ret < 0)
832                 return ret;
833 
834         ret = parse_nl_saddr(info, &saddr);
835         if (ret < 0)
836                 src = false;
837 
838         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
839         if (!msg)
840                 return -ENOMEM;
841 
842         reply = genlmsg_put_reply(msg, info, &tcp_metrics_nl_family, 0,
843                                   info->genlhdr->cmd);
844         if (!reply)
845                 goto nla_put_failure;
846 
847         hash ^= net_hash_mix(net);
848         hash = hash_32(hash, tcp_metrics_hash_log);
849         ret = -ESRCH;
850         rcu_read_lock();
851         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
852              tm = rcu_dereference(tm->tcpm_next)) {
853                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
854                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
855                     net_eq(tm_net(tm), net)) {
856                         ret = tcp_metrics_fill_info(msg, tm);
857                         break;
858                 }
859         }
860         rcu_read_unlock();
861         if (ret < 0)
862                 goto out_free;
863 
864         genlmsg_end(msg, reply);
865         return genlmsg_reply(msg, info);
866 
867 nla_put_failure:
868         ret = -EMSGSIZE;
869 
870 out_free:
871         nlmsg_free(msg);
872         return ret;
873 }
874 
875 static void tcp_metrics_flush_all(struct net *net)
876 {
877         unsigned int max_rows = 1U << tcp_metrics_hash_log;
878         struct tcpm_hash_bucket *hb = tcp_metrics_hash;
879         struct tcp_metrics_block *tm;
880         unsigned int row;
881 
882         for (row = 0; row < max_rows; row++, hb++) {
883                 struct tcp_metrics_block __rcu **pp;
884                 bool match;
885 
886                 spin_lock_bh(&tcp_metrics_lock);
887                 pp = &hb->chain;
888                 for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
889                         match = net ? net_eq(tm_net(tm), net) :
890                                 !refcount_read(&tm_net(tm)->count);
891                         if (match) {
892                                 *pp = tm->tcpm_next;
893                                 kfree_rcu(tm, rcu_head);
894                         } else {
895                                 pp = &tm->tcpm_next;
896                         }
897                 }
898                 spin_unlock_bh(&tcp_metrics_lock);
899         }
900 }
901 
902 static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info)
903 {
904         struct tcpm_hash_bucket *hb;
905         struct tcp_metrics_block *tm;
906         struct tcp_metrics_block __rcu **pp;
907         struct inetpeer_addr saddr, daddr;
908         unsigned int hash;
909         struct net *net = genl_info_net(info);
910         int ret;
911         bool src = true, found = false;
912 
913         ret = parse_nl_addr(info, &daddr, &hash, 1);
914         if (ret < 0)
915                 return ret;
916         if (ret > 0) {
917                 tcp_metrics_flush_all(net);
918                 return 0;
919         }
920         ret = parse_nl_saddr(info, &saddr);
921         if (ret < 0)
922                 src = false;
923 
924         hash ^= net_hash_mix(net);
925         hash = hash_32(hash, tcp_metrics_hash_log);
926         hb = tcp_metrics_hash + hash;
927         pp = &hb->chain;
928         spin_lock_bh(&tcp_metrics_lock);
929         for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
930                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
931                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
932                     net_eq(tm_net(tm), net)) {
933                         *pp = tm->tcpm_next;
934                         kfree_rcu(tm, rcu_head);
935                         found = true;
936                 } else {
937                         pp = &tm->tcpm_next;
938                 }
939         }
940         spin_unlock_bh(&tcp_metrics_lock);
941         if (!found)
942                 return -ESRCH;
943         return 0;
944 }
945 
946 static const struct genl_ops tcp_metrics_nl_ops[] = {
947         {
948                 .cmd = TCP_METRICS_CMD_GET,
949                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
950                 .doit = tcp_metrics_nl_cmd_get,
951                 .dumpit = tcp_metrics_nl_dump,
952         },
953         {
954                 .cmd = TCP_METRICS_CMD_DEL,
955                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
956                 .doit = tcp_metrics_nl_cmd_del,
957                 .flags = GENL_ADMIN_PERM,
958         },
959 };
960 
961 static struct genl_family tcp_metrics_nl_family __ro_after_init = {
962         .hdrsize        = 0,
963         .name           = TCP_METRICS_GENL_NAME,
964         .version        = TCP_METRICS_GENL_VERSION,
965         .maxattr        = TCP_METRICS_ATTR_MAX,
966         .policy = tcp_metrics_nl_policy,
967         .netnsok        = true,
968         .module         = THIS_MODULE,
969         .ops            = tcp_metrics_nl_ops,
970         .n_ops          = ARRAY_SIZE(tcp_metrics_nl_ops),
971 };
972 
973 static unsigned int tcpmhash_entries;
974 static int __init set_tcpmhash_entries(char *str)
975 {
976         ssize_t ret;
977 
978         if (!str)
979                 return 0;
980 
981         ret = kstrtouint(str, 0, &tcpmhash_entries);
982         if (ret)
983                 return 0;
984 
985         return 1;
986 }
987 __setup("tcpmhash_entries=", set_tcpmhash_entries);
988 
989 static int __net_init tcp_net_metrics_init(struct net *net)
990 {
991         size_t size;
992         unsigned int slots;
993 
994         if (!net_eq(net, &init_net))
995                 return 0;
996 
997         slots = tcpmhash_entries;
998         if (!slots) {
999                 if (totalram_pages() >= 128 * 1024)
1000                         slots = 16 * 1024;
1001                 else
1002                         slots = 8 * 1024;
1003         }
1004 
1005         tcp_metrics_hash_log = order_base_2(slots);
1006         size = sizeof(struct tcpm_hash_bucket) << tcp_metrics_hash_log;
1007 
1008         tcp_metrics_hash = kvzalloc(size, GFP_KERNEL);
1009         if (!tcp_metrics_hash)
1010                 return -ENOMEM;
1011 
1012         return 0;
1013 }
1014 
1015 static void __net_exit tcp_net_metrics_exit_batch(struct list_head *net_exit_list)
1016 {
1017         tcp_metrics_flush_all(NULL);
1018 }
1019 
1020 static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
1021         .init           =       tcp_net_metrics_init,
1022         .exit_batch     =       tcp_net_metrics_exit_batch,
1023 };
1024 
1025 void __init tcp_metrics_init(void)
1026 {
1027         int ret;
1028 
1029         ret = register_pernet_subsys(&tcp_net_metrics_ops);
1030         if (ret < 0)
1031                 panic("Could not allocate the tcp_metrics hash table\n");
1032 
1033         ret = genl_register_family(&tcp_metrics_nl_family);
1034         if (ret < 0)
1035                 panic("Could not register tcp_metrics generic netlink\n");
1036 }
1037 

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