net/ipv4/tcp_metrics.c

   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         struct net                      *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(const struct tcp_metrics_block *tm)
  55 {
  56         /* Paired with the WRITE_ONCE() in tcpm_new() */
  57         return READ_ONCE(tm->tcpm_net);
  58 }
  59
  60 static bool tcp_metric_locked(struct tcp_metrics_block *tm,
  61                               enum tcp_metric_index idx)
  62 {
  63         /* Paired with WRITE_ONCE() in tcpm_suck_dst() */
  64         return READ_ONCE(tm->tcpm_lock) & (1 << idx);
  65 }
  66
  67 static u32 tcp_metric_get(const struct tcp_metrics_block *tm,
  68                           enum tcp_metric_index idx)
  69 {
  70         /* Paired with WRITE_ONCE() in tcp_metric_set() */
  71         return READ_ONCE(tm->tcpm_vals[idx]);
  72 }
  73
  74 static void tcp_metric_set(struct tcp_metrics_block *tm,
  75                            enum tcp_metric_index idx,
  76                            u32 val)
  77 {
  78         /* Paired with READ_ONCE() in tcp_metric_get() */
  79         WRITE_ONCE(tm->tcpm_vals[idx], val);
  80 }
  81
  82 static bool addr_same(const struct inetpeer_addr *a,
  83                       const struct inetpeer_addr *b)
  84 {
  85         return (a->family == b->family) && !inetpeer_addr_cmp(a, b);
  86 }
  87
  88 struct tcpm_hash_bucket {
  89         struct tcp_metrics_block __rcu  *chain;
  90 };
  91
  92 static struct tcpm_hash_bucket  *tcp_metrics_hash __read_mostly;
  93 static unsigned int             tcp_metrics_hash_log __read_mostly;
  94
  95 static DEFINE_SPINLOCK(tcp_metrics_lock);
  96 static DEFINE_SEQLOCK(fastopen_seqlock);
  97
  98 static void tcpm_suck_dst(struct tcp_metrics_block *tm,
  99                           const struct dst_entry *dst,
 100                           bool fastopen_clear)
 101 {
 102         u32 msval;
 103         u32 val;
 104
 105         WRITE_ONCE(tm->tcpm_stamp, jiffies);
 106
 107         val = 0;
 108         if (dst_metric_locked(dst, RTAX_RTT))
 109                 val |= 1 << TCP_METRIC_RTT;
 110         if (dst_metric_locked(dst, RTAX_RTTVAR))
 111                 val |= 1 << TCP_METRIC_RTTVAR;
 112         if (dst_metric_locked(dst, RTAX_SSTHRESH))
 113                 val |= 1 << TCP_METRIC_SSTHRESH;
 114         if (dst_metric_locked(dst, RTAX_CWND))
 115                 val |= 1 << TCP_METRIC_CWND;
 116         if (dst_metric_locked(dst, RTAX_REORDERING))
 117                 val |= 1 << TCP_METRIC_REORDERING;
 118         /* Paired with READ_ONCE() in tcp_metric_locked() */
 119         WRITE_ONCE(tm->tcpm_lock, val);
 120
 121         msval = dst_metric_raw(dst, RTAX_RTT);
 122         tcp_metric_set(tm, TCP_METRIC_RTT, msval * USEC_PER_MSEC);
 123
 124         msval = dst_metric_raw(dst, RTAX_RTTVAR);
 125         tcp_metric_set(tm, TCP_METRIC_RTTVAR, msval * USEC_PER_MSEC);
 126         tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 127                        dst_metric_raw(dst, RTAX_SSTHRESH));
 128         tcp_metric_set(tm, TCP_METRIC_CWND,
 129                        dst_metric_raw(dst, RTAX_CWND));
 130         tcp_metric_set(tm, TCP_METRIC_REORDERING,
 131                        dst_metric_raw(dst, RTAX_REORDERING));
 132         if (fastopen_clear) {
 133                 write_seqlock(&fastopen_seqlock);
 134                 tm->tcpm_fastopen.mss = 0;
 135                 tm->tcpm_fastopen.syn_loss = 0;
 136                 tm->tcpm_fastopen.try_exp = 0;
 137                 tm->tcpm_fastopen.cookie.exp = false;
 138                 tm->tcpm_fastopen.cookie.len = 0;
 139                 write_sequnlock(&fastopen_seqlock);
 140         }
 141 }
 142
 143 #define TCP_METRICS_TIMEOUT             (60 * 60 * HZ)
 144
 145 static void tcpm_check_stamp(struct tcp_metrics_block *tm,
 146                              const struct dst_entry *dst)
 147 {
 148         unsigned long limit;
 149
 150         if (!tm)
 151                 return;
 152         limit = READ_ONCE(tm->tcpm_stamp) + TCP_METRICS_TIMEOUT;
 153         if (unlikely(time_after(jiffies, limit)))
 154                 tcpm_suck_dst(tm, dst, false);
 155 }
 156
 157 #define TCP_METRICS_RECLAIM_DEPTH       5
 158 #define TCP_METRICS_RECLAIM_PTR         (struct tcp_metrics_block *) 0x1UL
 159
 160 #define deref_locked(p) \
 161         rcu_dereference_protected(p, lockdep_is_held(&tcp_metrics_lock))
 162
 163 static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
 164                                           struct inetpeer_addr *saddr,
 165                                           struct inetpeer_addr *daddr,
 166                                           unsigned int hash)
 167 {
 168         struct tcp_metrics_block *tm;
 169         struct net *net;
 170         bool reclaim = false;
 171
 172         spin_lock_bh(&tcp_metrics_lock);
 173         net = dev_net(dst->dev);
 174
 175         /* While waiting for the spin-lock the cache might have been populated
 176          * with this entry and so we have to check again.
 177          */
 178         tm = __tcp_get_metrics(saddr, daddr, net, hash);
 179         if (tm == TCP_METRICS_RECLAIM_PTR) {
 180                 reclaim = true;
 181                 tm = NULL;
 182         }
 183         if (tm) {
 184                 tcpm_check_stamp(tm, dst);
 185                 goto out_unlock;
 186         }
 187
 188         if (unlikely(reclaim)) {
 189                 struct tcp_metrics_block *oldest;
 190
 191                 oldest = deref_locked(tcp_metrics_hash[hash].chain);
 192                 for (tm = deref_locked(oldest->tcpm_next); tm;
 193                      tm = deref_locked(tm->tcpm_next)) {
 194                         if (time_before(READ_ONCE(tm->tcpm_stamp),
 195                                         READ_ONCE(oldest->tcpm_stamp)))
 196                                 oldest = tm;
 197                 }
 198                 tm = oldest;
 199         } else {
 200                 tm = kzalloc(sizeof(*tm), GFP_ATOMIC);
 201                 if (!tm)
 202                         goto out_unlock;
 203         }
 204         /* Paired with the READ_ONCE() in tm_net() */
 205         WRITE_ONCE(tm->tcpm_net, net);
 206
 207         tm->tcpm_saddr = *saddr;
 208         tm->tcpm_daddr = *daddr;
 209
 210         tcpm_suck_dst(tm, dst, reclaim);
 211
 212         if (likely(!reclaim)) {
 213                 tm->tcpm_next = tcp_metrics_hash[hash].chain;
 214                 rcu_assign_pointer(tcp_metrics_hash[hash].chain, tm);
 215         }
 216
 217 out_unlock:
 218         spin_unlock_bh(&tcp_metrics_lock);
 219         return tm;
 220 }
 221
 222 static struct tcp_metrics_block *tcp_get_encode(struct tcp_metrics_block *tm, int depth)
 223 {
 224         if (tm)
 225                 return tm;
 226         if (depth > TCP_METRICS_RECLAIM_DEPTH)
 227                 return TCP_METRICS_RECLAIM_PTR;
 228         return NULL;
 229 }
 230
 231 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
 232                                                    const struct inetpeer_addr *daddr,
 233                                                    struct net *net, unsigned int hash)
 234 {
 235         struct tcp_metrics_block *tm;
 236         int depth = 0;
 237
 238         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
 239              tm = rcu_dereference(tm->tcpm_next)) {
 240                 if (addr_same(&tm->tcpm_saddr, saddr) &&
 241                     addr_same(&tm->tcpm_daddr, daddr) &&
 242                     net_eq(tm_net(tm), net))
 243                         break;
 244                 depth++;
 245         }
 246         return tcp_get_encode(tm, depth);
 247 }
 248
 249 static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
 250                                                        struct dst_entry *dst)
 251 {
 252         struct tcp_metrics_block *tm;
 253         struct inetpeer_addr saddr, daddr;
 254         unsigned int hash;
 255         struct net *net;
 256
 257         saddr.family = req->rsk_ops->family;
 258         daddr.family = req->rsk_ops->family;
 259         switch (daddr.family) {
 260         case AF_INET:
 261                 inetpeer_set_addr_v4(&saddr, inet_rsk(req)->ir_loc_addr);
 262                 inetpeer_set_addr_v4(&daddr, inet_rsk(req)->ir_rmt_addr);
 263                 hash = ipv4_addr_hash(inet_rsk(req)->ir_rmt_addr);
 264                 break;
 265 #if IS_ENABLED(CONFIG_IPV6)
 266         case AF_INET6:
 267                 inetpeer_set_addr_v6(&saddr, &inet_rsk(req)->ir_v6_loc_addr);
 268                 inetpeer_set_addr_v6(&daddr, &inet_rsk(req)->ir_v6_rmt_addr);
 269                 hash = ipv6_addr_hash(&inet_rsk(req)->ir_v6_rmt_addr);
 270                 break;
 271 #endif
 272         default:
 273                 return NULL;
 274         }
 275
 276         net = dev_net(dst->dev);
 277         hash ^= net_hash_mix(net);
 278         hash = hash_32(hash, tcp_metrics_hash_log);
 279
 280         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
 281              tm = rcu_dereference(tm->tcpm_next)) {
 282                 if (addr_same(&tm->tcpm_saddr, &saddr) &&
 283                     addr_same(&tm->tcpm_daddr, &daddr) &&
 284                     net_eq(tm_net(tm), net))
 285                         break;
 286         }
 287         tcpm_check_stamp(tm, dst);
 288         return tm;
 289 }
 290
 291 static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
 292                                                  struct dst_entry *dst,
 293                                                  bool create)
 294 {
 295         struct tcp_metrics_block *tm;
 296         struct inetpeer_addr saddr, daddr;
 297         unsigned int hash;
 298         struct net *net;
 299
 300         if (sk->sk_family == AF_INET) {
 301                 inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
 302                 inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
 303                 hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
 304         }
 305 #if IS_ENABLED(CONFIG_IPV6)
 306         else if (sk->sk_family == AF_INET6) {
 307                 if (ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
 308                         inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
 309                         inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
 310                         hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
 311                 } else {
 312                         inetpeer_set_addr_v6(&saddr, &sk->sk_v6_rcv_saddr);
 313                         inetpeer_set_addr_v6(&daddr, &sk->sk_v6_daddr);
 314                         hash = ipv6_addr_hash(&sk->sk_v6_daddr);
 315                 }
 316         }
 317 #endif
 318         else
 319                 return NULL;
 320
 321         net = dev_net(dst->dev);
 322         hash ^= net_hash_mix(net);
 323         hash = hash_32(hash, tcp_metrics_hash_log);
 324
 325         tm = __tcp_get_metrics(&saddr, &daddr, net, hash);
 326         if (tm == TCP_METRICS_RECLAIM_PTR)
 327                 tm = NULL;
 328         if (!tm && create)
 329                 tm = tcpm_new(dst, &saddr, &daddr, hash);
 330         else
 331                 tcpm_check_stamp(tm, dst);
 332
 333         return tm;
 334 }
 335
 336 /* Save metrics learned by this TCP session.  This function is called
 337  * only, when TCP finishes successfully i.e. when it enters TIME-WAIT
 338  * or goes from LAST-ACK to CLOSE.
 339  */
 340 void tcp_update_metrics(struct sock *sk)
 341 {
 342         const struct inet_connection_sock *icsk = inet_csk(sk);
 343         struct dst_entry *dst = __sk_dst_get(sk);
 344         struct tcp_sock *tp = tcp_sk(sk);
 345         struct net *net = sock_net(sk);
 346         struct tcp_metrics_block *tm;
 347         unsigned long rtt;
 348         u32 val;
 349         int m;
 350
 351         sk_dst_confirm(sk);
 352         if (READ_ONCE(net->ipv4.sysctl_tcp_nometrics_save) || !dst)
 353                 return;
 354
 355         rcu_read_lock();
 356         if (icsk->icsk_backoff || !tp->srtt_us) {
 357                 /* This session failed to estimate rtt. Why?
 358                  * Probably, no packets returned in time.  Reset our
 359                  * results.
 360                  */
 361                 tm = tcp_get_metrics(sk, dst, false);
 362                 if (tm && !tcp_metric_locked(tm, TCP_METRIC_RTT))
 363                         tcp_metric_set(tm, TCP_METRIC_RTT, 0);
 364                 goto out_unlock;
 365         } else
 366                 tm = tcp_get_metrics(sk, dst, true);
 367
 368         if (!tm)
 369                 goto out_unlock;
 370
 371         rtt = tcp_metric_get(tm, TCP_METRIC_RTT);
 372         m = rtt - tp->srtt_us;
 373
 374         /* If newly calculated rtt larger than stored one, store new
 375          * one. Otherwise, use EWMA. Remember, rtt overestimation is
 376          * always better than underestimation.
 377          */
 378         if (!tcp_metric_locked(tm, TCP_METRIC_RTT)) {
 379                 if (m <= 0)
 380                         rtt = tp->srtt_us;
 381                 else
 382                         rtt -= (m >> 3);
 383                 tcp_metric_set(tm, TCP_METRIC_RTT, rtt);
 384         }
 385
 386         if (!tcp_metric_locked(tm, TCP_METRIC_RTTVAR)) {
 387                 unsigned long var;
 388
 389                 if (m < 0)
 390                         m = -m;
 391
 392                 /* Scale deviation to rttvar fixed point */
 393                 m >>= 1;
 394                 if (m < tp->mdev_us)
 395                         m = tp->mdev_us;
 396
 397                 var = tcp_metric_get(tm, TCP_METRIC_RTTVAR);
 398                 if (m >= var)
 399                         var = m;
 400                 else
 401                         var -= (var - m) >> 2;
 402
 403                 tcp_metric_set(tm, TCP_METRIC_RTTVAR, var);
 404         }
 405
 406         if (tcp_in_initial_slowstart(tp)) {
 407                 /* Slow start still did not finish. */
 408                 if (!READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) &&
 409                     !tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 410                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 411                         if (val && (tcp_snd_cwnd(tp) >> 1) > val)
 412                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 413                                                tcp_snd_cwnd(tp) >> 1);
 414                 }
 415                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 416                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 417                         if (tcp_snd_cwnd(tp) > val)
 418                                 tcp_metric_set(tm, TCP_METRIC_CWND,
 419                                                tcp_snd_cwnd(tp));
 420                 }
 421         } else if (!tcp_in_slow_start(tp) &&
 422                    icsk->icsk_ca_state == TCP_CA_Open) {
 423                 /* Cong. avoidance phase, cwnd is reliable. */
 424                 if (!READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) &&
 425                     !tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
 426                         tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 427                                        max(tcp_snd_cwnd(tp) >> 1, tp->snd_ssthresh));
 428                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 429                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 430                         tcp_metric_set(tm, TCP_METRIC_CWND, (val + tcp_snd_cwnd(tp)) >> 1);
 431                 }
 432         } else {
 433                 /* Else slow start did not finish, cwnd is non-sense,
 434                  * ssthresh may be also invalid.
 435                  */
 436                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 437                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 438                         tcp_metric_set(tm, TCP_METRIC_CWND,
 439                                        (val + tp->snd_ssthresh) >> 1);
 440                 }
 441                 if (!READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) &&
 442                     !tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 443                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 444                         if (val && tp->snd_ssthresh > val)
 445                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 446                                                tp->snd_ssthresh);
 447                 }
 448                 if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {
 449                         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 450                         if (val < tp->reordering &&
 451                             tp->reordering !=
 452                             READ_ONCE(net->ipv4.sysctl_tcp_reordering))
 453                                 tcp_metric_set(tm, TCP_METRIC_REORDERING,
 454                                                tp->reordering);
 455                 }
 456         }
 457         WRITE_ONCE(tm->tcpm_stamp, jiffies);
 458 out_unlock:
 459         rcu_read_unlock();
 460 }
 461
 462 /* Initialize metrics on socket. */
 463
 464 void tcp_init_metrics(struct sock *sk)
 465 {
 466         struct dst_entry *dst = __sk_dst_get(sk);
 467         struct tcp_sock *tp = tcp_sk(sk);
 468         struct net *net = sock_net(sk);
 469         struct tcp_metrics_block *tm;
 470         u32 val, crtt = 0; /* cached RTT scaled by 8 */
 471
 472         sk_dst_confirm(sk);
 473         if (!dst)
 474                 goto reset;
 475
 476         rcu_read_lock();
 477         tm = tcp_get_metrics(sk, dst, true);
 478         if (!tm) {
 479                 rcu_read_unlock();
 480                 goto reset;
 481         }
 482
 483         if (tcp_metric_locked(tm, TCP_METRIC_CWND))
 484                 tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
 485
 486         val = READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) ?
 487               0 : tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 488         if (val) {
 489                 tp->snd_ssthresh = val;
 490                 if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
 491                         tp->snd_ssthresh = tp->snd_cwnd_clamp;
 492         } else {
 493                 /* ssthresh may have been reduced unnecessarily during.
 494                  * 3WHS. Restore it back to its initial default.
 495                  */
 496                 tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
 497         }
 498         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 499         if (val && tp->reordering != val)
 500                 tp->reordering = val;
 501
 502         crtt = tcp_metric_get(tm, TCP_METRIC_RTT);
 503         rcu_read_unlock();
 504 reset:
 505         /* The initial RTT measurement from the SYN/SYN-ACK is not ideal
 506          * to seed the RTO for later data packets because SYN packets are
 507          * small. Use the per-dst cached values to seed the RTO but keep
 508          * the RTT estimator variables intact (e.g., srtt, mdev, rttvar).
 509          * Later the RTO will be updated immediately upon obtaining the first
 510          * data RTT sample (tcp_rtt_estimator()). Hence the cached RTT only
 511          * influences the first RTO but not later RTT estimation.
 512          *
 513          * But if RTT is not available from the SYN (due to retransmits or
 514          * syn cookies) or the cache, force a conservative 3secs timeout.
 515          *
 516          * A bit of theory. RTT is time passed after "normal" sized packet
 517          * is sent until it is ACKed. In normal circumstances sending small
 518          * packets force peer to delay ACKs and calculation is correct too.
 519          * The algorithm is adaptive and, provided we follow specs, it
 520          * NEVER underestimate RTT. BUT! If peer tries to make some clever
 521          * tricks sort of "quick acks" for time long enough to decrease RTT
 522          * to low value, and then abruptly stops to do it and starts to delay
 523          * ACKs, wait for troubles.
 524          */
 525         if (crtt > tp->srtt_us) {
 526                 /* Set RTO like tcp_rtt_estimator(), but from cached RTT. */
 527                 crtt /= 8 * USEC_PER_SEC / HZ;
 528                 inet_csk(sk)->icsk_rto = crtt + max(2 * crtt, tcp_rto_min(sk));
 529         } else if (tp->srtt_us == 0) {
 530                 /* RFC6298: 5.7 We've failed to get a valid RTT sample from
 531                  * 3WHS. This is most likely due to retransmission,
 532                  * including spurious one. Reset the RTO back to 3secs
 533                  * from the more aggressive 1sec to avoid more spurious
 534                  * retransmission.
 535                  */
 536                 tp->rttvar_us = jiffies_to_usecs(TCP_TIMEOUT_FALLBACK);
 537                 tp->mdev_us = tp->mdev_max_us = tp->rttvar_us;
 538
 539                 inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
 540         }
 541 }
 542
 543 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst)
 544 {
 545         struct tcp_metrics_block *tm;
 546         bool ret;
 547
 548         if (!dst)
 549                 return false;
 550
 551         rcu_read_lock();
 552         tm = __tcp_get_metrics_req(req, dst);
 553         if (tm && tcp_metric_get(tm, TCP_METRIC_RTT))
 554                 ret = true;
 555         else
 556                 ret = false;
 557         rcu_read_unlock();
 558
 559         return ret;
 560 }
 561
 562 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
 563                             struct tcp_fastopen_cookie *cookie)
 564 {
 565         struct tcp_metrics_block *tm;
 566
 567         rcu_read_lock();
 568         tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
 569         if (tm) {
 570                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 571                 unsigned int seq;
 572
 573                 do {
 574                         seq = read_seqbegin(&fastopen_seqlock);
 575                         if (tfom->mss)
 576                                 *mss = tfom->mss;
 577                         *cookie = tfom->cookie;
 578                         if (cookie->len <= 0 && tfom->try_exp == 1)
 579                                 cookie->exp = true;
 580                 } while (read_seqretry(&fastopen_seqlock, seq));
 581         }
 582         rcu_read_unlock();
 583 }
 584
 585 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
 586                             struct tcp_fastopen_cookie *cookie, bool syn_lost,
 587                             u16 try_exp)
 588 {
 589         struct dst_entry *dst = __sk_dst_get(sk);
 590         struct tcp_metrics_block *tm;
 591
 592         if (!dst)
 593                 return;
 594         rcu_read_lock();
 595         tm = tcp_get_metrics(sk, dst, true);
 596         if (tm) {
 597                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 598
 599                 write_seqlock_bh(&fastopen_seqlock);
 600                 if (mss)
 601                         tfom->mss = mss;
 602                 if (cookie && cookie->len > 0)
 603                         tfom->cookie = *cookie;
 604                 else if (try_exp > tfom->try_exp &&
 605                          tfom->cookie.len <= 0 && !tfom->cookie.exp)
 606                         tfom->try_exp = try_exp;
 607                 if (syn_lost) {
 608                         ++tfom->syn_loss;
 609                         tfom->last_syn_loss = jiffies;
 610                 } else
 611                         tfom->syn_loss = 0;
 612                 write_sequnlock_bh(&fastopen_seqlock);
 613         }
 614         rcu_read_unlock();
 615 }
 616
 617 static struct genl_family tcp_metrics_nl_family;
 618
 619 static const struct nla_policy tcp_metrics_nl_policy[TCP_METRICS_ATTR_MAX + 1] = {
 620         [TCP_METRICS_ATTR_ADDR_IPV4]    = { .type = NLA_U32, },
 621         [TCP_METRICS_ATTR_ADDR_IPV6]    = { .type = NLA_BINARY,
 622                                             .len = sizeof(struct in6_addr), },
 623         /* Following attributes are not received for GET/DEL,
 624          * we keep them for reference
 625          */
 626 #if 0
 627         [TCP_METRICS_ATTR_AGE]          = { .type = NLA_MSECS, },
 628         [TCP_METRICS_ATTR_TW_TSVAL]     = { .type = NLA_U32, },
 629         [TCP_METRICS_ATTR_TW_TS_STAMP]  = { .type = NLA_S32, },
 630         [TCP_METRICS_ATTR_VALS]         = { .type = NLA_NESTED, },
 631         [TCP_METRICS_ATTR_FOPEN_MSS]    = { .type = NLA_U16, },
 632         [TCP_METRICS_ATTR_FOPEN_SYN_DROPS]      = { .type = NLA_U16, },
 633         [TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS]    = { .type = NLA_MSECS, },
 634         [TCP_METRICS_ATTR_FOPEN_COOKIE] = { .type = NLA_BINARY,
 635                                             .len = TCP_FASTOPEN_COOKIE_MAX, },
 636 #endif
 637 };
 638
 639 /* Add attributes, caller cancels its header on failure */
 640 static int tcp_metrics_fill_info(struct sk_buff *msg,
 641                                  struct tcp_metrics_block *tm)
 642 {
 643         struct nlattr *nest;
 644         int i;
 645
 646         switch (tm->tcpm_daddr.family) {
 647         case AF_INET:
 648                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_ADDR_IPV4,
 649                                     inetpeer_get_addr_v4(&tm->tcpm_daddr)) < 0)
 650                         goto nla_put_failure;
 651                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_SADDR_IPV4,
 652                                     inetpeer_get_addr_v4(&tm->tcpm_saddr)) < 0)
 653                         goto nla_put_failure;
 654                 break;
 655         case AF_INET6:
 656                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_ADDR_IPV6,
 657                                      inetpeer_get_addr_v6(&tm->tcpm_daddr)) < 0)
 658                         goto nla_put_failure;
 659                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_SADDR_IPV6,
 660                                      inetpeer_get_addr_v6(&tm->tcpm_saddr)) < 0)
 661                         goto nla_put_failure;
 662                 break;
 663         default:
 664                 return -EAFNOSUPPORT;
 665         }
 666
 667         if (nla_put_msecs(msg, TCP_METRICS_ATTR_AGE,
 668                           jiffies - READ_ONCE(tm->tcpm_stamp),
 669                           TCP_METRICS_ATTR_PAD) < 0)
 670                 goto nla_put_failure;
 671
 672         {
 673                 int n = 0;
 674
 675                 nest = nla_nest_start_noflag(msg, TCP_METRICS_ATTR_VALS);
 676                 if (!nest)
 677                         goto nla_put_failure;
 678                 for (i = 0; i < TCP_METRIC_MAX_KERNEL + 1; i++) {
 679                         u32 val = tcp_metric_get(tm, i);
 680
 681                         if (!val)
 682                                 continue;
 683                         if (i == TCP_METRIC_RTT) {
 684                                 if (nla_put_u32(msg, TCP_METRIC_RTT_US + 1,
 685                                                 val) < 0)
 686                                         goto nla_put_failure;
 687                                 n++;
 688                                 val = max(val / 1000, 1U);
 689                         }
 690                         if (i == TCP_METRIC_RTTVAR) {
 691                                 if (nla_put_u32(msg, TCP_METRIC_RTTVAR_US + 1,
 692                                                 val) < 0)
 693                                         goto nla_put_failure;
 694                                 n++;
 695                                 val = max(val / 1000, 1U);
 696                         }
 697                         if (nla_put_u32(msg, i + 1, val) < 0)
 698                                 goto nla_put_failure;
 699                         n++;
 700                 }
 701                 if (n)
 702                         nla_nest_end(msg, nest);
 703                 else
 704                         nla_nest_cancel(msg, nest);
 705         }
 706
 707         {
 708                 struct tcp_fastopen_metrics tfom_copy[1], *tfom;
 709                 unsigned int seq;
 710
 711                 do {
 712                         seq = read_seqbegin(&fastopen_seqlock);
 713                         tfom_copy[0] = tm->tcpm_fastopen;
 714                 } while (read_seqretry(&fastopen_seqlock, seq));
 715
 716                 tfom = tfom_copy;
 717                 if (tfom->mss &&
 718                     nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_MSS,
 719                                 tfom->mss) < 0)
 720                         goto nla_put_failure;
 721                 if (tfom->syn_loss &&
 722                     (nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROPS,
 723                                 tfom->syn_loss) < 0 ||
 724                      nla_put_msecs(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS,
 725                                 jiffies - tfom->last_syn_loss,
 726                                 TCP_METRICS_ATTR_PAD) < 0))
 727                         goto nla_put_failure;
 728                 if (tfom->cookie.len > 0 &&
 729                     nla_put(msg, TCP_METRICS_ATTR_FOPEN_COOKIE,
 730                             tfom->cookie.len, tfom->cookie.val) < 0)
 731                         goto nla_put_failure;
 732         }
 733
 734         return 0;
 735
 736 nla_put_failure:
 737         return -EMSGSIZE;
 738 }
 739
 740 static int tcp_metrics_dump_info(struct sk_buff *skb,
 741                                  struct netlink_callback *cb,
 742                                  struct tcp_metrics_block *tm)
 743 {
 744         void *hdr;
 745
 746         hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
 747                           &tcp_metrics_nl_family, NLM_F_MULTI,
 748                           TCP_METRICS_CMD_GET);
 749         if (!hdr)
 750                 return -EMSGSIZE;
 751
 752         if (tcp_metrics_fill_info(skb, tm) < 0)
 753                 goto nla_put_failure;
 754
 755         genlmsg_end(skb, hdr);
 756         return 0;
 757
 758 nla_put_failure:
 759         genlmsg_cancel(skb, hdr);
 760         return -EMSGSIZE;
 761 }
 762
 763 static int tcp_metrics_nl_dump(struct sk_buff *skb,
 764                                struct netlink_callback *cb)
 765 {
 766         struct net *net = sock_net(skb->sk);
 767         unsigned int max_rows = 1U << tcp_metrics_hash_log;
 768         unsigned int row, s_row = cb->args[0];
 769         int s_col = cb->args[1], col = s_col;
 770
 771         for (row = s_row; row < max_rows; row++, s_col = 0) {
 772                 struct tcp_metrics_block *tm;
 773                 struct tcpm_hash_bucket *hb = tcp_metrics_hash + row;
 774
 775                 rcu_read_lock();
 776                 for (col = 0, tm = rcu_dereference(hb->chain); tm;
 777                      tm = rcu_dereference(tm->tcpm_next), col++) {
 778                         if (!net_eq(tm_net(tm), net))
 779                                 continue;
 780                         if (col < s_col)
 781                                 continue;
 782                         if (tcp_metrics_dump_info(skb, cb, tm) < 0) {
 783                                 rcu_read_unlock();
 784                                 goto done;
 785                         }
 786                 }
 787                 rcu_read_unlock();
 788         }
 789
 790 done:
 791         cb->args[0] = row;
 792         cb->args[1] = col;
 793         return skb->len;
 794 }
 795
 796 static int __parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 797                            unsigned int *hash, int optional, int v4, int v6)
 798 {
 799         struct nlattr *a;
 800
 801         a = info->attrs[v4];
 802         if (a) {
 803                 inetpeer_set_addr_v4(addr, nla_get_in_addr(a));
 804                 if (hash)
 805                         *hash = ipv4_addr_hash(inetpeer_get_addr_v4(addr));
 806                 return 0;
 807         }
 808         a = info->attrs[v6];
 809         if (a) {
 810                 struct in6_addr in6;
 811
 812                 if (nla_len(a) != sizeof(struct in6_addr))
 813                         return -EINVAL;
 814                 in6 = nla_get_in6_addr(a);
 815                 inetpeer_set_addr_v6(addr, &in6);
 816                 if (hash)
 817                         *hash = ipv6_addr_hash(inetpeer_get_addr_v6(addr));
 818                 return 0;
 819         }
 820         return optional ? 1 : -EAFNOSUPPORT;
 821 }
 822
 823 static int parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 824                          unsigned int *hash, int optional)
 825 {
 826         return __parse_nl_addr(info, addr, hash, optional,
 827                                TCP_METRICS_ATTR_ADDR_IPV4,
 828                                TCP_METRICS_ATTR_ADDR_IPV6);
 829 }
 830
 831 static int parse_nl_saddr(struct genl_info *info, struct inetpeer_addr *addr)
 832 {
 833         return __parse_nl_addr(info, addr, NULL, 0,
 834                                TCP_METRICS_ATTR_SADDR_IPV4,
 835                                TCP_METRICS_ATTR_SADDR_IPV6);
 836 }
 837
 838 static int tcp_metrics_nl_cmd_get(struct sk_buff *skb, struct genl_info *info)
 839 {
 840         struct tcp_metrics_block *tm;
 841         struct inetpeer_addr saddr, daddr;
 842         unsigned int hash;
 843         struct sk_buff *msg;
 844         struct net *net = genl_info_net(info);
 845         void *reply;
 846         int ret;
 847         bool src = true;
 848
 849         ret = parse_nl_addr(info, &daddr, &hash, 0);
 850         if (ret < 0)
 851                 return ret;
 852
 853         ret = parse_nl_saddr(info, &saddr);
 854         if (ret < 0)
 855                 src = false;
 856
 857         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 858         if (!msg)
 859                 return -ENOMEM;
 860
 861         reply = genlmsg_put_reply(msg, info, &tcp_metrics_nl_family, 0,
 862                                   info->genlhdr->cmd);
 863         if (!reply)
 864                 goto nla_put_failure;
 865
 866         hash ^= net_hash_mix(net);
 867         hash = hash_32(hash, tcp_metrics_hash_log);
 868         ret = -ESRCH;
 869         rcu_read_lock();
 870         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
 871              tm = rcu_dereference(tm->tcpm_next)) {
 872                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
 873                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
 874                     net_eq(tm_net(tm), net)) {
 875                         ret = tcp_metrics_fill_info(msg, tm);
 876                         break;
 877                 }
 878         }
 879         rcu_read_unlock();
 880         if (ret < 0)
 881                 goto out_free;
 882
 883         genlmsg_end(msg, reply);
 884         return genlmsg_reply(msg, info);
 885
 886 nla_put_failure:
 887         ret = -EMSGSIZE;
 888
 889 out_free:
 890         nlmsg_free(msg);
 891         return ret;
 892 }
 893
 894 static void tcp_metrics_flush_all(struct net *net)
 895 {
 896         unsigned int max_rows = 1U << tcp_metrics_hash_log;
 897         struct tcpm_hash_bucket *hb = tcp_metrics_hash;
 898         struct tcp_metrics_block *tm;
 899         unsigned int row;
 900
 901         for (row = 0; row < max_rows; row++, hb++) {
 902                 struct tcp_metrics_block __rcu **pp;
 903                 bool match;
 904
 905                 spin_lock_bh(&tcp_metrics_lock);
 906                 pp = &hb->chain;
 907                 for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
 908                         match = net ? net_eq(tm_net(tm), net) :
 909                                 !refcount_read(&tm_net(tm)->ns.count);
 910                         if (match) {
 911                                 *pp = tm->tcpm_next;
 912                                 kfree_rcu(tm, rcu_head);
 913                         } else {
 914                                 pp = &tm->tcpm_next;
 915                         }
 916                 }
 917                 spin_unlock_bh(&tcp_metrics_lock);
 918         }
 919 }
 920
 921 static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info)
 922 {
 923         struct tcpm_hash_bucket *hb;
 924         struct tcp_metrics_block *tm;
 925         struct tcp_metrics_block __rcu **pp;
 926         struct inetpeer_addr saddr, daddr;
 927         unsigned int hash;
 928         struct net *net = genl_info_net(info);
 929         int ret;
 930         bool src = true, found = false;
 931
 932         ret = parse_nl_addr(info, &daddr, &hash, 1);
 933         if (ret < 0)
 934                 return ret;
 935         if (ret > 0) {
 936                 tcp_metrics_flush_all(net);
 937                 return 0;
 938         }
 939         ret = parse_nl_saddr(info, &saddr);
 940         if (ret < 0)
 941                 src = false;
 942
 943         hash ^= net_hash_mix(net);
 944         hash = hash_32(hash, tcp_metrics_hash_log);
 945         hb = tcp_metrics_hash + hash;
 946         pp = &hb->chain;
 947         spin_lock_bh(&tcp_metrics_lock);
 948         for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
 949                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
 950                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
 951                     net_eq(tm_net(tm), net)) {
 952                         *pp = tm->tcpm_next;
 953                         kfree_rcu(tm, rcu_head);
 954                         found = true;
 955                 } else {
 956                         pp = &tm->tcpm_next;
 957                 }
 958         }
 959         spin_unlock_bh(&tcp_metrics_lock);
 960         if (!found)
 961                 return -ESRCH;
 962         return 0;
 963 }
 964
 965 static const struct genl_small_ops tcp_metrics_nl_ops[] = {
 966         {
 967                 .cmd = TCP_METRICS_CMD_GET,
 968                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 969                 .doit = tcp_metrics_nl_cmd_get,
 970                 .dumpit = tcp_metrics_nl_dump,
 971         },
 972         {
 973                 .cmd = TCP_METRICS_CMD_DEL,
 974                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 975                 .doit = tcp_metrics_nl_cmd_del,
 976                 .flags = GENL_ADMIN_PERM,
 977         },
 978 };
 979
 980 static struct genl_family tcp_metrics_nl_family __ro_after_init = {
 981         .hdrsize        = 0,
 982         .name           = TCP_METRICS_GENL_NAME,
 983         .version        = TCP_METRICS_GENL_VERSION,
 984         .maxattr        = TCP_METRICS_ATTR_MAX,
 985         .policy = tcp_metrics_nl_policy,
 986         .netnsok        = true,
 987         .module         = THIS_MODULE,
 988         .small_ops      = tcp_metrics_nl_ops,
 989         .n_small_ops    = ARRAY_SIZE(tcp_metrics_nl_ops),
 990         .resv_start_op  = TCP_METRICS_CMD_DEL + 1,
 991 };
 992
 993 static unsigned int tcpmhash_entries __initdata;
 994 static int __init set_tcpmhash_entries(char *str)
 995 {
 996         ssize_t ret;
 997
 998         if (!str)
 999                 return 0;
1000
1001         ret = kstrtouint(str, 0, &tcpmhash_entries);
1002         if (ret)
1003                 return 0;
1004
1005         return 1;
1006 }
1007 __setup("tcpmhash_entries=", set_tcpmhash_entries);
1008
1009 static void __init tcp_metrics_hash_alloc(void)
1010 {
1011         unsigned int slots = tcpmhash_entries;
1012         size_t size;
1013
1014         if (!slots) {
1015                 if (totalram_pages() >= 128 * 1024)
1016                         slots = 16 * 1024;
1017                 else
1018                         slots = 8 * 1024;
1019         }
1020
1021         tcp_metrics_hash_log = order_base_2(slots);
1022         size = sizeof(struct tcpm_hash_bucket) << tcp_metrics_hash_log;
1023
1024         tcp_metrics_hash = kvzalloc(size, GFP_KERNEL);
1025         if (!tcp_metrics_hash)
1026                 panic("Could not allocate the tcp_metrics hash table\n");
1027 }
1028
1029 static void __net_exit tcp_net_metrics_exit_batch(struct list_head *net_exit_list)
1030 {
1031         tcp_metrics_flush_all(NULL);
1032 }
1033
1034 static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
1035         .exit_batch     =       tcp_net_metrics_exit_batch,
1036 };
1037
1038 void __init tcp_metrics_init(void)
1039 {
1040         int ret;
1041
1042         tcp_metrics_hash_alloc();
1043
1044         ret = register_pernet_subsys(&tcp_net_metrics_ops);
1045         if (ret < 0)
1046                 panic("Could not register tcp_net_metrics_ops\n");
1047
1048         ret = genl_register_family(&tcp_metrics_nl_family);
1049         if (ret < 0)
1050                 panic("Could not register tcp_metrics generic netlink\n");
1051 }