net/ipv4/tcp_metrics.c

   1 #include <linux/rcupdate.h>
   2 #include <linux/spinlock.h>
   3 #include <linux/jiffies.h>
   4 #include <linux/bootmem.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
  12 #include <net/inet_connection_sock.h>
  13 #include <net/net_namespace.h>
  14 #include <net/request_sock.h>
  15 #include <net/inetpeer.h>
  16 #include <net/sock.h>
  17 #include <net/ipv6.h>
  18 #include <net/dst.h>
  19 #include <net/tcp.h>
  20
  21 int sysctl_tcp_nometrics_save __read_mostly;
  22
  23 enum tcp_metric_index {
  24         TCP_METRIC_RTT,
  25         TCP_METRIC_RTTVAR,
  26         TCP_METRIC_SSTHRESH,
  27         TCP_METRIC_CWND,
  28         TCP_METRIC_REORDERING,
  29
  30         /* Always last.  */
  31         TCP_METRIC_MAX,
  32 };
  33
  34 struct tcp_fastopen_metrics {
  35         u16     mss;
  36         u16     syn_loss:10;            /* Recurring Fast Open SYN losses */
  37         unsigned long   last_syn_loss;  /* Last Fast Open SYN loss */
  38         struct  tcp_fastopen_cookie     cookie;
  39 };
  40
  41 struct tcp_metrics_block {
  42         struct tcp_metrics_block __rcu  *tcpm_next;
  43         struct inetpeer_addr            tcpm_addr;
  44         unsigned long                   tcpm_stamp;
  45         u32                             tcpm_ts;
  46         u32                             tcpm_ts_stamp;
  47         u32                             tcpm_lock;
  48         u32                             tcpm_vals[TCP_METRIC_MAX];
  49         struct tcp_fastopen_metrics     tcpm_fastopen;
  50 };
  51
  52 static bool tcp_metric_locked(struct tcp_metrics_block *tm,
  53                               enum tcp_metric_index idx)
  54 {
  55         return tm->tcpm_lock & (1 << idx);
  56 }
  57
  58 static u32 tcp_metric_get(struct tcp_metrics_block *tm,
  59                           enum tcp_metric_index idx)
  60 {
  61         return tm->tcpm_vals[idx];
  62 }
  63
  64 static u32 tcp_metric_get_jiffies(struct tcp_metrics_block *tm,
  65                                   enum tcp_metric_index idx)
  66 {
  67         return msecs_to_jiffies(tm->tcpm_vals[idx]);
  68 }
  69
  70 static void tcp_metric_set(struct tcp_metrics_block *tm,
  71                            enum tcp_metric_index idx,
  72                            u32 val)
  73 {
  74         tm->tcpm_vals[idx] = val;
  75 }
  76
  77 static void tcp_metric_set_msecs(struct tcp_metrics_block *tm,
  78                                  enum tcp_metric_index idx,
  79                                  u32 val)
  80 {
  81         tm->tcpm_vals[idx] = jiffies_to_msecs(val);
  82 }
  83
  84 static bool addr_same(const struct inetpeer_addr *a,
  85                       const struct inetpeer_addr *b)
  86 {
  87         const struct in6_addr *a6, *b6;
  88
  89         if (a->family != b->family)
  90                 return false;
  91         if (a->family == AF_INET)
  92                 return a->addr.a4 == b->addr.a4;
  93
  94         a6 = (const struct in6_addr *) &a->addr.a6[0];
  95         b6 = (const struct in6_addr *) &b->addr.a6[0];
  96
  97         return ipv6_addr_equal(a6, b6);
  98 }
  99
 100 struct tcpm_hash_bucket {
 101         struct tcp_metrics_block __rcu  *chain;
 102 };
 103
 104 static DEFINE_SPINLOCK(tcp_metrics_lock);
 105
 106 static void tcpm_suck_dst(struct tcp_metrics_block *tm, struct dst_entry *dst)
 107 {
 108         u32 val;
 109
 110         tm->tcpm_stamp = jiffies;
 111
 112         val = 0;
 113         if (dst_metric_locked(dst, RTAX_RTT))
 114                 val |= 1 << TCP_METRIC_RTT;
 115         if (dst_metric_locked(dst, RTAX_RTTVAR))
 116                 val |= 1 << TCP_METRIC_RTTVAR;
 117         if (dst_metric_locked(dst, RTAX_SSTHRESH))
 118                 val |= 1 << TCP_METRIC_SSTHRESH;
 119         if (dst_metric_locked(dst, RTAX_CWND))
 120                 val |= 1 << TCP_METRIC_CWND;
 121         if (dst_metric_locked(dst, RTAX_REORDERING))
 122                 val |= 1 << TCP_METRIC_REORDERING;
 123         tm->tcpm_lock = val;
 124
 125         tm->tcpm_vals[TCP_METRIC_RTT] = dst_metric_raw(dst, RTAX_RTT);
 126         tm->tcpm_vals[TCP_METRIC_RTTVAR] = dst_metric_raw(dst, RTAX_RTTVAR);
 127         tm->tcpm_vals[TCP_METRIC_SSTHRESH] = dst_metric_raw(dst, RTAX_SSTHRESH);
 128         tm->tcpm_vals[TCP_METRIC_CWND] = dst_metric_raw(dst, RTAX_CWND);
 129         tm->tcpm_vals[TCP_METRIC_REORDERING] = dst_metric_raw(dst, RTAX_REORDERING);
 130         tm->tcpm_ts = 0;
 131         tm->tcpm_ts_stamp = 0;
 132         tm->tcpm_fastopen.mss = 0;
 133         tm->tcpm_fastopen.syn_loss = 0;
 134         tm->tcpm_fastopen.cookie.len = 0;
 135 }
 136
 137 static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
 138                                           struct inetpeer_addr *addr,
 139                                           unsigned int hash,
 140                                           bool reclaim)
 141 {
 142         struct tcp_metrics_block *tm;
 143         struct net *net;
 144
 145         spin_lock_bh(&tcp_metrics_lock);
 146         net = dev_net(dst->dev);
 147         if (unlikely(reclaim)) {
 148                 struct tcp_metrics_block *oldest;
 149
 150                 oldest = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain);
 151                 for (tm = rcu_dereference(oldest->tcpm_next); tm;
 152                      tm = rcu_dereference(tm->tcpm_next)) {
 153                         if (time_before(tm->tcpm_stamp, oldest->tcpm_stamp))
 154                                 oldest = tm;
 155                 }
 156                 tm = oldest;
 157         } else {
 158                 tm = kmalloc(sizeof(*tm), GFP_ATOMIC);
 159                 if (!tm)
 160                         goto out_unlock;
 161         }
 162         tm->tcpm_addr = *addr;
 163
 164         tcpm_suck_dst(tm, dst);
 165
 166         if (likely(!reclaim)) {
 167                 tm->tcpm_next = net->ipv4.tcp_metrics_hash[hash].chain;
 168                 rcu_assign_pointer(net->ipv4.tcp_metrics_hash[hash].chain, tm);
 169         }
 170
 171 out_unlock:
 172         spin_unlock_bh(&tcp_metrics_lock);
 173         return tm;
 174 }
 175
 176 #define TCP_METRICS_TIMEOUT             (60 * 60 * HZ)
 177
 178 static void tcpm_check_stamp(struct tcp_metrics_block *tm, struct dst_entry *dst)
 179 {
 180         if (tm && unlikely(time_after(jiffies, tm->tcpm_stamp + TCP_METRICS_TIMEOUT)))
 181                 tcpm_suck_dst(tm, dst);
 182 }
 183
 184 #define TCP_METRICS_RECLAIM_DEPTH       5
 185 #define TCP_METRICS_RECLAIM_PTR         (struct tcp_metrics_block *) 0x1UL
 186
 187 static struct tcp_metrics_block *tcp_get_encode(struct tcp_metrics_block *tm, int depth)
 188 {
 189         if (tm)
 190                 return tm;
 191         if (depth > TCP_METRICS_RECLAIM_DEPTH)
 192                 return TCP_METRICS_RECLAIM_PTR;
 193         return NULL;
 194 }
 195
 196 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *addr,
 197                                                    struct net *net, unsigned int hash)
 198 {
 199         struct tcp_metrics_block *tm;
 200         int depth = 0;
 201
 202         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 203              tm = rcu_dereference(tm->tcpm_next)) {
 204                 if (addr_same(&tm->tcpm_addr, addr))
 205                         break;
 206                 depth++;
 207         }
 208         return tcp_get_encode(tm, depth);
 209 }
 210
 211 static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
 212                                                        struct dst_entry *dst)
 213 {
 214         struct tcp_metrics_block *tm;
 215         struct inetpeer_addr addr;
 216         unsigned int hash;
 217         struct net *net;
 218
 219         addr.family = req->rsk_ops->family;
 220         switch (addr.family) {
 221         case AF_INET:
 222                 addr.addr.a4 = inet_rsk(req)->rmt_addr;
 223                 hash = (__force unsigned int) addr.addr.a4;
 224                 break;
 225         case AF_INET6:
 226                 *(struct in6_addr *)addr.addr.a6 = inet6_rsk(req)->rmt_addr;
 227                 hash = ipv6_addr_hash(&inet6_rsk(req)->rmt_addr);
 228                 break;
 229         default:
 230                 return NULL;
 231         }
 232
 233         net = dev_net(dst->dev);
 234         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 235
 236         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 237              tm = rcu_dereference(tm->tcpm_next)) {
 238                 if (addr_same(&tm->tcpm_addr, &addr))
 239                         break;
 240         }
 241         tcpm_check_stamp(tm, dst);
 242         return tm;
 243 }
 244
 245 static struct tcp_metrics_block *__tcp_get_metrics_tw(struct inet_timewait_sock *tw)
 246 {
 247         struct inet6_timewait_sock *tw6;
 248         struct tcp_metrics_block *tm;
 249         struct inetpeer_addr addr;
 250         unsigned int hash;
 251         struct net *net;
 252
 253         addr.family = tw->tw_family;
 254         switch (addr.family) {
 255         case AF_INET:
 256                 addr.addr.a4 = tw->tw_daddr;
 257                 hash = (__force unsigned int) addr.addr.a4;
 258                 break;
 259         case AF_INET6:
 260                 tw6 = inet6_twsk((struct sock *)tw);
 261                 *(struct in6_addr *)addr.addr.a6 = tw6->tw_v6_daddr;
 262                 hash = ipv6_addr_hash(&tw6->tw_v6_daddr);
 263                 break;
 264         default:
 265                 return NULL;
 266         }
 267
 268         net = twsk_net(tw);
 269         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 270
 271         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 272              tm = rcu_dereference(tm->tcpm_next)) {
 273                 if (addr_same(&tm->tcpm_addr, &addr))
 274                         break;
 275         }
 276         return tm;
 277 }
 278
 279 static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
 280                                                  struct dst_entry *dst,
 281                                                  bool create)
 282 {
 283         struct tcp_metrics_block *tm;
 284         struct inetpeer_addr addr;
 285         unsigned int hash;
 286         struct net *net;
 287         bool reclaim;
 288
 289         addr.family = sk->sk_family;
 290         switch (addr.family) {
 291         case AF_INET:
 292                 addr.addr.a4 = inet_sk(sk)->inet_daddr;
 293                 hash = (__force unsigned int) addr.addr.a4;
 294                 break;
 295         case AF_INET6:
 296                 *(struct in6_addr *)addr.addr.a6 = inet6_sk(sk)->daddr;
 297                 hash = ipv6_addr_hash(&inet6_sk(sk)->daddr);
 298                 break;
 299         default:
 300                 return NULL;
 301         }
 302
 303         net = dev_net(dst->dev);
 304         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 305
 306         tm = __tcp_get_metrics(&addr, net, hash);
 307         reclaim = false;
 308         if (tm == TCP_METRICS_RECLAIM_PTR) {
 309                 reclaim = true;
 310                 tm = NULL;
 311         }
 312         if (!tm && create)
 313                 tm = tcpm_new(dst, &addr, hash, reclaim);
 314         else
 315                 tcpm_check_stamp(tm, dst);
 316
 317         return tm;
 318 }
 319
 320 /* Save metrics learned by this TCP session.  This function is called
 321  * only, when TCP finishes successfully i.e. when it enters TIME-WAIT
 322  * or goes from LAST-ACK to CLOSE.
 323  */
 324 void tcp_update_metrics(struct sock *sk)
 325 {
 326         const struct inet_connection_sock *icsk = inet_csk(sk);
 327         struct dst_entry *dst = __sk_dst_get(sk);
 328         struct tcp_sock *tp = tcp_sk(sk);
 329         struct tcp_metrics_block *tm;
 330         unsigned long rtt;
 331         u32 val;
 332         int m;
 333
 334         if (sysctl_tcp_nometrics_save || !dst)
 335                 return;
 336
 337         if (dst->flags & DST_HOST)
 338                 dst_confirm(dst);
 339
 340         rcu_read_lock();
 341         if (icsk->icsk_backoff || !tp->srtt) {
 342                 /* This session failed to estimate rtt. Why?
 343                  * Probably, no packets returned in time.  Reset our
 344                  * results.
 345                  */
 346                 tm = tcp_get_metrics(sk, dst, false);
 347                 if (tm && !tcp_metric_locked(tm, TCP_METRIC_RTT))
 348                         tcp_metric_set(tm, TCP_METRIC_RTT, 0);
 349                 goto out_unlock;
 350         } else
 351                 tm = tcp_get_metrics(sk, dst, true);
 352
 353         if (!tm)
 354                 goto out_unlock;
 355
 356         rtt = tcp_metric_get_jiffies(tm, TCP_METRIC_RTT);
 357         m = rtt - tp->srtt;
 358
 359         /* If newly calculated rtt larger than stored one, store new
 360          * one. Otherwise, use EWMA. Remember, rtt overestimation is
 361          * always better than underestimation.
 362          */
 363         if (!tcp_metric_locked(tm, TCP_METRIC_RTT)) {
 364                 if (m <= 0)
 365                         rtt = tp->srtt;
 366                 else
 367                         rtt -= (m >> 3);
 368                 tcp_metric_set_msecs(tm, TCP_METRIC_RTT, rtt);
 369         }
 370
 371         if (!tcp_metric_locked(tm, TCP_METRIC_RTTVAR)) {
 372                 unsigned long var;
 373
 374                 if (m < 0)
 375                         m = -m;
 376
 377                 /* Scale deviation to rttvar fixed point */
 378                 m >>= 1;
 379                 if (m < tp->mdev)
 380                         m = tp->mdev;
 381
 382                 var = tcp_metric_get_jiffies(tm, TCP_METRIC_RTTVAR);
 383                 if (m >= var)
 384                         var = m;
 385                 else
 386                         var -= (var - m) >> 2;
 387
 388                 tcp_metric_set_msecs(tm, TCP_METRIC_RTTVAR, var);
 389         }
 390
 391         if (tcp_in_initial_slowstart(tp)) {
 392                 /* Slow start still did not finish. */
 393                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 394                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 395                         if (val && (tp->snd_cwnd >> 1) > val)
 396                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 397                                                tp->snd_cwnd >> 1);
 398                 }
 399                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 400                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 401                         if (tp->snd_cwnd > val)
 402                                 tcp_metric_set(tm, TCP_METRIC_CWND,
 403                                                tp->snd_cwnd);
 404                 }
 405         } else if (tp->snd_cwnd > tp->snd_ssthresh &&
 406                    icsk->icsk_ca_state == TCP_CA_Open) {
 407                 /* Cong. avoidance phase, cwnd is reliable. */
 408                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
 409                         tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 410                                        max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
 411                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 412                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 413                         tcp_metric_set(tm, TCP_METRIC_CWND, (val + tp->snd_cwnd) >> 1);
 414                 }
 415         } else {
 416                 /* Else slow start did not finish, cwnd is non-sense,
 417                  * ssthresh may be also invalid.
 418                  */
 419                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 420                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 421                         tcp_metric_set(tm, TCP_METRIC_CWND,
 422                                        (val + tp->snd_ssthresh) >> 1);
 423                 }
 424                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 425                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 426                         if (val && tp->snd_ssthresh > val)
 427                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 428                                                tp->snd_ssthresh);
 429                 }
 430                 if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {
 431                         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 432                         if (val < tp->reordering &&
 433                             tp->reordering != sysctl_tcp_reordering)
 434                                 tcp_metric_set(tm, TCP_METRIC_REORDERING,
 435                                                tp->reordering);
 436                 }
 437         }
 438         tm->tcpm_stamp = jiffies;
 439 out_unlock:
 440         rcu_read_unlock();
 441 }
 442
 443 /* Initialize metrics on socket. */
 444
 445 void tcp_init_metrics(struct sock *sk)
 446 {
 447         struct dst_entry *dst = __sk_dst_get(sk);
 448         struct tcp_sock *tp = tcp_sk(sk);
 449         struct tcp_metrics_block *tm;
 450         u32 val;
 451
 452         if (dst == NULL)
 453                 goto reset;
 454
 455         dst_confirm(dst);
 456
 457         rcu_read_lock();
 458         tm = tcp_get_metrics(sk, dst, true);
 459         if (!tm) {
 460                 rcu_read_unlock();
 461                 goto reset;
 462         }
 463
 464         if (tcp_metric_locked(tm, TCP_METRIC_CWND))
 465                 tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
 466
 467         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 468         if (val) {
 469                 tp->snd_ssthresh = val;
 470                 if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
 471                         tp->snd_ssthresh = tp->snd_cwnd_clamp;
 472         } else {
 473                 /* ssthresh may have been reduced unnecessarily during.
 474                  * 3WHS. Restore it back to its initial default.
 475                  */
 476                 tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
 477         }
 478         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 479         if (val && tp->reordering != val) {
 480                 tcp_disable_fack(tp);
 481                 tcp_disable_early_retrans(tp);
 482                 tp->reordering = val;
 483         }
 484
 485         val = tcp_metric_get(tm, TCP_METRIC_RTT);
 486         if (val == 0 || tp->srtt == 0) {
 487                 rcu_read_unlock();
 488                 goto reset;
 489         }
 490         /* Initial rtt is determined from SYN,SYN-ACK.
 491          * The segment is small and rtt may appear much
 492          * less than real one. Use per-dst memory
 493          * to make it more realistic.
 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         val = msecs_to_jiffies(val);
 505         if (val > tp->srtt) {
 506                 tp->srtt = val;
 507                 tp->rtt_seq = tp->snd_nxt;
 508         }
 509         val = tcp_metric_get_jiffies(tm, TCP_METRIC_RTTVAR);
 510         if (val > tp->mdev) {
 511                 tp->mdev = val;
 512                 tp->mdev_max = tp->rttvar = max(tp->mdev, tcp_rto_min(sk));
 513         }
 514         rcu_read_unlock();
 515
 516         tcp_set_rto(sk);
 517 reset:
 518         if (tp->srtt == 0) {
 519                 /* RFC6298: 5.7 We've failed to get a valid RTT sample from
 520                  * 3WHS. This is most likely due to retransmission,
 521                  * including spurious one. Reset the RTO back to 3secs
 522                  * from the more aggressive 1sec to avoid more spurious
 523                  * retransmission.
 524                  */
 525                 tp->mdev = tp->mdev_max = tp->rttvar = TCP_TIMEOUT_FALLBACK;
 526                 inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
 527         }
 528         /* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
 529          * retransmitted. In light of RFC6298 more aggressive 1sec
 530          * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
 531          * retransmission has occurred.
 532          */
 533         if (tp->total_retrans > 1)
 534                 tp->snd_cwnd = 1;
 535         else
 536                 tp->snd_cwnd = tcp_init_cwnd(tp, dst);
 537         tp->snd_cwnd_stamp = tcp_time_stamp;
 538 }
 539
 540 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, bool paws_check)
 541 {
 542         struct tcp_metrics_block *tm;
 543         bool ret;
 544
 545         if (!dst)
 546                 return false;
 547
 548         rcu_read_lock();
 549         tm = __tcp_get_metrics_req(req, dst);
 550         if (paws_check) {
 551                 if (tm &&
 552                     (u32)get_seconds() - tm->tcpm_ts_stamp < TCP_PAWS_MSL &&
 553                     (s32)(tm->tcpm_ts - req->ts_recent) > TCP_PAWS_WINDOW)
 554                         ret = false;
 555                 else
 556                         ret = true;
 557         } else {
 558                 if (tm && tcp_metric_get(tm, TCP_METRIC_RTT) && tm->tcpm_ts_stamp)
 559                         ret = true;
 560                 else
 561                         ret = false;
 562         }
 563         rcu_read_unlock();
 564
 565         return ret;
 566 }
 567 EXPORT_SYMBOL_GPL(tcp_peer_is_proven);
 568
 569 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst)
 570 {
 571         struct tcp_metrics_block *tm;
 572
 573         rcu_read_lock();
 574         tm = tcp_get_metrics(sk, dst, true);
 575         if (tm) {
 576                 struct tcp_sock *tp = tcp_sk(sk);
 577
 578                 if ((u32)get_seconds() - tm->tcpm_ts_stamp <= TCP_PAWS_MSL) {
 579                         tp->rx_opt.ts_recent_stamp = tm->tcpm_ts_stamp;
 580                         tp->rx_opt.ts_recent = tm->tcpm_ts;
 581                 }
 582         }
 583         rcu_read_unlock();
 584 }
 585 EXPORT_SYMBOL_GPL(tcp_fetch_timewait_stamp);
 586
 587 /* VJ's idea. Save last timestamp seen from this destination and hold
 588  * it at least for normal timewait interval to use for duplicate
 589  * segment detection in subsequent connections, before they enter
 590  * synchronized state.
 591  */
 592 bool tcp_remember_stamp(struct sock *sk)
 593 {
 594         struct dst_entry *dst = __sk_dst_get(sk);
 595         bool ret = false;
 596
 597         if (dst) {
 598                 struct tcp_metrics_block *tm;
 599
 600                 rcu_read_lock();
 601                 tm = tcp_get_metrics(sk, dst, true);
 602                 if (tm) {
 603                         struct tcp_sock *tp = tcp_sk(sk);
 604
 605                         if ((s32)(tm->tcpm_ts - tp->rx_opt.ts_recent) <= 0 ||
 606                             ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 607                              tm->tcpm_ts_stamp <= (u32)tp->rx_opt.ts_recent_stamp)) {
 608                                 tm->tcpm_ts_stamp = (u32)tp->rx_opt.ts_recent_stamp;
 609                                 tm->tcpm_ts = tp->rx_opt.ts_recent;
 610                         }
 611                         ret = true;
 612                 }
 613                 rcu_read_unlock();
 614         }
 615         return ret;
 616 }
 617
 618 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw)
 619 {
 620         struct tcp_metrics_block *tm;
 621         bool ret = false;
 622
 623         rcu_read_lock();
 624         tm = __tcp_get_metrics_tw(tw);
 625         if (tm) {
 626                 const struct tcp_timewait_sock *tcptw;
 627                 struct sock *sk = (struct sock *) tw;
 628
 629                 tcptw = tcp_twsk(sk);
 630                 if ((s32)(tm->tcpm_ts - tcptw->tw_ts_recent) <= 0 ||
 631                     ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 632                      tm->tcpm_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) {
 633                         tm->tcpm_ts_stamp = (u32)tcptw->tw_ts_recent_stamp;
 634                         tm->tcpm_ts        = tcptw->tw_ts_recent;
 635                 }
 636                 ret = true;
 637         }
 638         rcu_read_unlock();
 639
 640         return ret;
 641 }
 642
 643 static DEFINE_SEQLOCK(fastopen_seqlock);
 644
 645 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
 646                             struct tcp_fastopen_cookie *cookie,
 647                             int *syn_loss, unsigned long *last_syn_loss)
 648 {
 649         struct tcp_metrics_block *tm;
 650
 651         rcu_read_lock();
 652         tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
 653         if (tm) {
 654                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 655                 unsigned int seq;
 656
 657                 do {
 658                         seq = read_seqbegin(&fastopen_seqlock);
 659                         if (tfom->mss)
 660                                 *mss = tfom->mss;
 661                         *cookie = tfom->cookie;
 662                         *syn_loss = tfom->syn_loss;
 663                         *last_syn_loss = *syn_loss ? tfom->last_syn_loss : 0;
 664                 } while (read_seqretry(&fastopen_seqlock, seq));
 665         }
 666         rcu_read_unlock();
 667 }
 668
 669 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
 670                             struct tcp_fastopen_cookie *cookie, bool syn_lost)
 671 {
 672         struct tcp_metrics_block *tm;
 673
 674         rcu_read_lock();
 675         tm = tcp_get_metrics(sk, __sk_dst_get(sk), true);
 676         if (tm) {
 677                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 678
 679                 write_seqlock_bh(&fastopen_seqlock);
 680                 tfom->mss = mss;
 681                 if (cookie->len > 0)
 682                         tfom->cookie = *cookie;
 683                 if (syn_lost) {
 684                         ++tfom->syn_loss;
 685                         tfom->last_syn_loss = jiffies;
 686                 } else
 687                         tfom->syn_loss = 0;
 688                 write_sequnlock_bh(&fastopen_seqlock);
 689         }
 690         rcu_read_unlock();
 691 }
 692
 693 static unsigned int tcpmhash_entries;
 694 static int __init set_tcpmhash_entries(char *str)
 695 {
 696         ssize_t ret;
 697
 698         if (!str)
 699                 return 0;
 700
 701         ret = kstrtouint(str, 0, &tcpmhash_entries);
 702         if (ret)
 703                 return 0;
 704
 705         return 1;
 706 }
 707 __setup("tcpmhash_entries=", set_tcpmhash_entries);
 708
 709 static int __net_init tcp_net_metrics_init(struct net *net)
 710 {
 711         size_t size;
 712         unsigned int slots;
 713
 714         slots = tcpmhash_entries;
 715         if (!slots) {
 716                 if (totalram_pages >= 128 * 1024)
 717                         slots = 16 * 1024;
 718                 else
 719                         slots = 8 * 1024;
 720         }
 721
 722         net->ipv4.tcp_metrics_hash_log = order_base_2(slots);
 723         size = sizeof(struct tcpm_hash_bucket) << net->ipv4.tcp_metrics_hash_log;
 724
 725         net->ipv4.tcp_metrics_hash = kzalloc(size, GFP_KERNEL);
 726         if (!net->ipv4.tcp_metrics_hash)
 727                 return -ENOMEM;
 728
 729         return 0;
 730 }
 731
 732 static void __net_exit tcp_net_metrics_exit(struct net *net)
 733 {
 734         unsigned int i;
 735
 736         for (i = 0; i < (1U << net->ipv4.tcp_metrics_hash_log) ; i++) {
 737                 struct tcp_metrics_block *tm, *next;
 738
 739                 tm = rcu_dereference_protected(net->ipv4.tcp_metrics_hash[i].chain, 1);
 740                 while (tm) {
 741                         next = rcu_dereference_protected(tm->tcpm_next, 1);
 742                         kfree(tm);
 743                         tm = next;
 744                 }
 745         }
 746         kfree(net->ipv4.tcp_metrics_hash);
 747 }
 748
 749 static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
 750         .init   =       tcp_net_metrics_init,
 751         .exit   =       tcp_net_metrics_exit,
 752 };
 753
 754 void __init tcp_metrics_init(void)
 755 {
 756         register_pernet_subsys(&tcp_net_metrics_ops);
 757 }