net/ipv4/tcp_metrics.c

   1 #include <linux/rcupdate.h>
   2 #include <linux/spinlock.h>
   3 #include <linux/jiffies.h>
   4 #include <linux/module.h>
   5 #include <linux/cache.h>
   6 #include <linux/slab.h>
   7 #include <linux/init.h>
   8 #include <linux/tcp.h>
   9 #include <linux/hash.h>
  10 #include <linux/tcp_metrics.h>
  11 #include <linux/vmalloc.h>
  12
  13 #include <net/inet_connection_sock.h>
  14 #include <net/net_namespace.h>
  15 #include <net/request_sock.h>
  16 #include <net/inetpeer.h>
  17 #include <net/sock.h>
  18 #include <net/ipv6.h>
  19 #include <net/dst.h>
  20 #include <net/tcp.h>
  21 #include <net/genetlink.h>
  22
  23 int sysctl_tcp_nometrics_save __read_mostly;
  24
  25 struct tcp_fastopen_metrics {
  26         u16     mss;
  27         u16     syn_loss:10;            /* Recurring Fast Open SYN losses */
  28         unsigned long   last_syn_loss;  /* Last Fast Open SYN loss */
  29         struct  tcp_fastopen_cookie     cookie;
  30 };
  31
  32 struct tcp_metrics_block {
  33         struct tcp_metrics_block __rcu  *tcpm_next;
  34         struct inetpeer_addr            tcpm_addr;
  35         unsigned long                   tcpm_stamp;
  36         u32                             tcpm_ts;
  37         u32                             tcpm_ts_stamp;
  38         u32                             tcpm_lock;
  39         u32                             tcpm_vals[TCP_METRIC_MAX + 1];
  40         struct tcp_fastopen_metrics     tcpm_fastopen;
  41
  42         struct rcu_head                 rcu_head;
  43 };
  44
  45 static bool tcp_metric_locked(struct tcp_metrics_block *tm,
  46                               enum tcp_metric_index idx)
  47 {
  48         return tm->tcpm_lock & (1 << idx);
  49 }
  50
  51 static u32 tcp_metric_get(struct tcp_metrics_block *tm,
  52                           enum tcp_metric_index idx)
  53 {
  54         return tm->tcpm_vals[idx];
  55 }
  56
  57 static u32 tcp_metric_get_jiffies(struct tcp_metrics_block *tm,
  58                                   enum tcp_metric_index idx)
  59 {
  60         return msecs_to_jiffies(tm->tcpm_vals[idx]);
  61 }
  62
  63 static void tcp_metric_set(struct tcp_metrics_block *tm,
  64                            enum tcp_metric_index idx,
  65                            u32 val)
  66 {
  67         tm->tcpm_vals[idx] = val;
  68 }
  69
  70 static void tcp_metric_set_msecs(struct tcp_metrics_block *tm,
  71                                  enum tcp_metric_index idx,
  72                                  u32 val)
  73 {
  74         tm->tcpm_vals[idx] = jiffies_to_msecs(val);
  75 }
  76
  77 static bool addr_same(const struct inetpeer_addr *a,
  78                       const struct inetpeer_addr *b)
  79 {
  80         const struct in6_addr *a6, *b6;
  81
  82         if (a->family != b->family)
  83                 return false;
  84         if (a->family == AF_INET)
  85                 return a->addr.a4 == b->addr.a4;
  86
  87         a6 = (const struct in6_addr *) &a->addr.a6[0];
  88         b6 = (const struct in6_addr *) &b->addr.a6[0];
  89
  90         return ipv6_addr_equal(a6, b6);
  91 }
  92
  93 struct tcpm_hash_bucket {
  94         struct tcp_metrics_block __rcu  *chain;
  95 };
  96
  97 static DEFINE_SPINLOCK(tcp_metrics_lock);
  98
  99 static void tcpm_suck_dst(struct tcp_metrics_block *tm, struct dst_entry *dst,
 100                           bool fastopen_clear)
 101 {
 102         u32 val;
 103
 104         tm->tcpm_stamp = jiffies;
 105
 106         val = 0;
 107         if (dst_metric_locked(dst, RTAX_RTT))
 108                 val |= 1 << TCP_METRIC_RTT;
 109         if (dst_metric_locked(dst, RTAX_RTTVAR))
 110                 val |= 1 << TCP_METRIC_RTTVAR;
 111         if (dst_metric_locked(dst, RTAX_SSTHRESH))
 112                 val |= 1 << TCP_METRIC_SSTHRESH;
 113         if (dst_metric_locked(dst, RTAX_CWND))
 114                 val |= 1 << TCP_METRIC_CWND;
 115         if (dst_metric_locked(dst, RTAX_REORDERING))
 116                 val |= 1 << TCP_METRIC_REORDERING;
 117         tm->tcpm_lock = val;
 118
 119         tm->tcpm_vals[TCP_METRIC_RTT] = dst_metric_raw(dst, RTAX_RTT);
 120         tm->tcpm_vals[TCP_METRIC_RTTVAR] = dst_metric_raw(dst, RTAX_RTTVAR);
 121         tm->tcpm_vals[TCP_METRIC_SSTHRESH] = dst_metric_raw(dst, RTAX_SSTHRESH);
 122         tm->tcpm_vals[TCP_METRIC_CWND] = dst_metric_raw(dst, RTAX_CWND);
 123         tm->tcpm_vals[TCP_METRIC_REORDERING] = dst_metric_raw(dst, RTAX_REORDERING);
 124         tm->tcpm_ts = 0;
 125         tm->tcpm_ts_stamp = 0;
 126         if (fastopen_clear) {
 127                 tm->tcpm_fastopen.mss = 0;
 128                 tm->tcpm_fastopen.syn_loss = 0;
 129                 tm->tcpm_fastopen.cookie.len = 0;
 130         }
 131 }
 132
 133 static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
 134                                           struct inetpeer_addr *addr,
 135                                           unsigned int hash,
 136                                           bool reclaim)
 137 {
 138         struct tcp_metrics_block *tm;
 139         struct net *net;
 140
 141         spin_lock_bh(&tcp_metrics_lock);
 142         net = dev_net(dst->dev);
 143         if (unlikely(reclaim)) {
 144                 struct tcp_metrics_block *oldest;
 145
 146                 oldest = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain);
 147                 for (tm = rcu_dereference(oldest->tcpm_next); tm;
 148                      tm = rcu_dereference(tm->tcpm_next)) {
 149                         if (time_before(tm->tcpm_stamp, oldest->tcpm_stamp))
 150                                 oldest = tm;
 151                 }
 152                 tm = oldest;
 153         } else {
 154                 tm = kmalloc(sizeof(*tm), GFP_ATOMIC);
 155                 if (!tm)
 156                         goto out_unlock;
 157         }
 158         tm->tcpm_addr = *addr;
 159
 160         tcpm_suck_dst(tm, dst, true);
 161
 162         if (likely(!reclaim)) {
 163                 tm->tcpm_next = net->ipv4.tcp_metrics_hash[hash].chain;
 164                 rcu_assign_pointer(net->ipv4.tcp_metrics_hash[hash].chain, tm);
 165         }
 166
 167 out_unlock:
 168         spin_unlock_bh(&tcp_metrics_lock);
 169         return tm;
 170 }
 171
 172 #define TCP_METRICS_TIMEOUT             (60 * 60 * HZ)
 173
 174 static void tcpm_check_stamp(struct tcp_metrics_block *tm, struct dst_entry *dst)
 175 {
 176         if (tm && unlikely(time_after(jiffies, tm->tcpm_stamp + TCP_METRICS_TIMEOUT)))
 177                 tcpm_suck_dst(tm, dst, false);
 178 }
 179
 180 #define TCP_METRICS_RECLAIM_DEPTH       5
 181 #define TCP_METRICS_RECLAIM_PTR         (struct tcp_metrics_block *) 0x1UL
 182
 183 static struct tcp_metrics_block *tcp_get_encode(struct tcp_metrics_block *tm, int depth)
 184 {
 185         if (tm)
 186                 return tm;
 187         if (depth > TCP_METRICS_RECLAIM_DEPTH)
 188                 return TCP_METRICS_RECLAIM_PTR;
 189         return NULL;
 190 }
 191
 192 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *addr,
 193                                                    struct net *net, unsigned int hash)
 194 {
 195         struct tcp_metrics_block *tm;
 196         int depth = 0;
 197
 198         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 199              tm = rcu_dereference(tm->tcpm_next)) {
 200                 if (addr_same(&tm->tcpm_addr, addr))
 201                         break;
 202                 depth++;
 203         }
 204         return tcp_get_encode(tm, depth);
 205 }
 206
 207 static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
 208                                                        struct dst_entry *dst)
 209 {
 210         struct tcp_metrics_block *tm;
 211         struct inetpeer_addr addr;
 212         unsigned int hash;
 213         struct net *net;
 214
 215         addr.family = req->rsk_ops->family;
 216         switch (addr.family) {
 217         case AF_INET:
 218                 addr.addr.a4 = inet_rsk(req)->rmt_addr;
 219                 hash = (__force unsigned int) addr.addr.a4;
 220                 break;
 221         case AF_INET6:
 222                 *(struct in6_addr *)addr.addr.a6 = inet6_rsk(req)->rmt_addr;
 223                 hash = ipv6_addr_hash(&inet6_rsk(req)->rmt_addr);
 224                 break;
 225         default:
 226                 return NULL;
 227         }
 228
 229         net = dev_net(dst->dev);
 230         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 231
 232         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 233              tm = rcu_dereference(tm->tcpm_next)) {
 234                 if (addr_same(&tm->tcpm_addr, &addr))
 235                         break;
 236         }
 237         tcpm_check_stamp(tm, dst);
 238         return tm;
 239 }
 240
 241 static struct tcp_metrics_block *__tcp_get_metrics_tw(struct inet_timewait_sock *tw)
 242 {
 243         struct inet6_timewait_sock *tw6;
 244         struct tcp_metrics_block *tm;
 245         struct inetpeer_addr addr;
 246         unsigned int hash;
 247         struct net *net;
 248
 249         addr.family = tw->tw_family;
 250         switch (addr.family) {
 251         case AF_INET:
 252                 addr.addr.a4 = tw->tw_daddr;
 253                 hash = (__force unsigned int) addr.addr.a4;
 254                 break;
 255         case AF_INET6:
 256                 tw6 = inet6_twsk((struct sock *)tw);
 257                 *(struct in6_addr *)addr.addr.a6 = tw6->tw_v6_daddr;
 258                 hash = ipv6_addr_hash(&tw6->tw_v6_daddr);
 259                 break;
 260         default:
 261                 return NULL;
 262         }
 263
 264         net = twsk_net(tw);
 265         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 266
 267         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 268              tm = rcu_dereference(tm->tcpm_next)) {
 269                 if (addr_same(&tm->tcpm_addr, &addr))
 270                         break;
 271         }
 272         return tm;
 273 }
 274
 275 static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
 276                                                  struct dst_entry *dst,
 277                                                  bool create)
 278 {
 279         struct tcp_metrics_block *tm;
 280         struct inetpeer_addr addr;
 281         unsigned int hash;
 282         struct net *net;
 283         bool reclaim;
 284
 285         addr.family = sk->sk_family;
 286         switch (addr.family) {
 287         case AF_INET:
 288                 addr.addr.a4 = inet_sk(sk)->inet_daddr;
 289                 hash = (__force unsigned int) addr.addr.a4;
 290                 break;
 291         case AF_INET6:
 292                 *(struct in6_addr *)addr.addr.a6 = inet6_sk(sk)->daddr;
 293                 hash = ipv6_addr_hash(&inet6_sk(sk)->daddr);
 294                 break;
 295         default:
 296                 return NULL;
 297         }
 298
 299         net = dev_net(dst->dev);
 300         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 301
 302         tm = __tcp_get_metrics(&addr, net, hash);
 303         reclaim = false;
 304         if (tm == TCP_METRICS_RECLAIM_PTR) {
 305                 reclaim = true;
 306                 tm = NULL;
 307         }
 308         if (!tm && create)
 309                 tm = tcpm_new(dst, &addr, hash, reclaim);
 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 tcp_metrics_block *tm;
 326         unsigned long rtt;
 327         u32 val;
 328         int m;
 329
 330         if (sysctl_tcp_nometrics_save || !dst)
 331                 return;
 332
 333         if (dst->flags & DST_HOST)
 334                 dst_confirm(dst);
 335
 336         rcu_read_lock();
 337         if (icsk->icsk_backoff || !tp->srtt) {
 338                 /* This session failed to estimate rtt. Why?
 339                  * Probably, no packets returned in time.  Reset our
 340                  * results.
 341                  */
 342                 tm = tcp_get_metrics(sk, dst, false);
 343                 if (tm && !tcp_metric_locked(tm, TCP_METRIC_RTT))
 344                         tcp_metric_set(tm, TCP_METRIC_RTT, 0);
 345                 goto out_unlock;
 346         } else
 347                 tm = tcp_get_metrics(sk, dst, true);
 348
 349         if (!tm)
 350                 goto out_unlock;
 351
 352         rtt = tcp_metric_get_jiffies(tm, TCP_METRIC_RTT);
 353         m = rtt - tp->srtt;
 354
 355         /* If newly calculated rtt larger than stored one, store new
 356          * one. Otherwise, use EWMA. Remember, rtt overestimation is
 357          * always better than underestimation.
 358          */
 359         if (!tcp_metric_locked(tm, TCP_METRIC_RTT)) {
 360                 if (m <= 0)
 361                         rtt = tp->srtt;
 362                 else
 363                         rtt -= (m >> 3);
 364                 tcp_metric_set_msecs(tm, TCP_METRIC_RTT, rtt);
 365         }
 366
 367         if (!tcp_metric_locked(tm, TCP_METRIC_RTTVAR)) {
 368                 unsigned long var;
 369
 370                 if (m < 0)
 371                         m = -m;
 372
 373                 /* Scale deviation to rttvar fixed point */
 374                 m >>= 1;
 375                 if (m < tp->mdev)
 376                         m = tp->mdev;
 377
 378                 var = tcp_metric_get_jiffies(tm, TCP_METRIC_RTTVAR);
 379                 if (m >= var)
 380                         var = m;
 381                 else
 382                         var -= (var - m) >> 2;
 383
 384                 tcp_metric_set_msecs(tm, TCP_METRIC_RTTVAR, var);
 385         }
 386
 387         if (tcp_in_initial_slowstart(tp)) {
 388                 /* Slow start still did not finish. */
 389                 if (!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 (tp->snd_cwnd > tp->snd_ssthresh &&
 402                    icsk->icsk_ca_state == TCP_CA_Open) {
 403                 /* Cong. avoidance phase, cwnd is reliable. */
 404                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
 405                         tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 406                                        max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
 407                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 408                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 409                         tcp_metric_set(tm, TCP_METRIC_CWND, (val + tp->snd_cwnd) >> 1);
 410                 }
 411         } else {
 412                 /* Else slow start did not finish, cwnd is non-sense,
 413                  * ssthresh may be also invalid.
 414                  */
 415                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 416                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 417                         tcp_metric_set(tm, TCP_METRIC_CWND,
 418                                        (val + tp->snd_ssthresh) >> 1);
 419                 }
 420                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 421                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 422                         if (val && tp->snd_ssthresh > val)
 423                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 424                                                tp->snd_ssthresh);
 425                 }
 426                 if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {
 427                         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 428                         if (val < tp->reordering &&
 429                             tp->reordering != sysctl_tcp_reordering)
 430                                 tcp_metric_set(tm, TCP_METRIC_REORDERING,
 431                                                tp->reordering);
 432                 }
 433         }
 434         tm->tcpm_stamp = jiffies;
 435 out_unlock:
 436         rcu_read_unlock();
 437 }
 438
 439 /* Initialize metrics on socket. */
 440
 441 void tcp_init_metrics(struct sock *sk)
 442 {
 443         struct dst_entry *dst = __sk_dst_get(sk);
 444         struct tcp_sock *tp = tcp_sk(sk);
 445         struct tcp_metrics_block *tm;
 446         u32 val;
 447
 448         if (dst == NULL)
 449                 goto reset;
 450
 451         dst_confirm(dst);
 452
 453         rcu_read_lock();
 454         tm = tcp_get_metrics(sk, dst, true);
 455         if (!tm) {
 456                 rcu_read_unlock();
 457                 goto reset;
 458         }
 459
 460         if (tcp_metric_locked(tm, TCP_METRIC_CWND))
 461                 tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
 462
 463         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 464         if (val) {
 465                 tp->snd_ssthresh = val;
 466                 if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
 467                         tp->snd_ssthresh = tp->snd_cwnd_clamp;
 468         } else {
 469                 /* ssthresh may have been reduced unnecessarily during.
 470                  * 3WHS. Restore it back to its initial default.
 471                  */
 472                 tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
 473         }
 474         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 475         if (val && tp->reordering != val) {
 476                 tcp_disable_fack(tp);
 477                 tcp_disable_early_retrans(tp);
 478                 tp->reordering = val;
 479         }
 480
 481         val = tcp_metric_get(tm, TCP_METRIC_RTT);
 482         if (val == 0 || tp->srtt == 0) {
 483                 rcu_read_unlock();
 484                 goto reset;
 485         }
 486         /* Initial rtt is determined from SYN,SYN-ACK.
 487          * The segment is small and rtt may appear much
 488          * less than real one. Use per-dst memory
 489          * to make it more realistic.
 490          *
 491          * A bit of theory. RTT is time passed after "normal" sized packet
 492          * is sent until it is ACKed. In normal circumstances sending small
 493          * packets force peer to delay ACKs and calculation is correct too.
 494          * The algorithm is adaptive and, provided we follow specs, it
 495          * NEVER underestimate RTT. BUT! If peer tries to make some clever
 496          * tricks sort of "quick acks" for time long enough to decrease RTT
 497          * to low value, and then abruptly stops to do it and starts to delay
 498          * ACKs, wait for troubles.
 499          */
 500         val = msecs_to_jiffies(val);
 501         if (val > tp->srtt) {
 502                 tp->srtt = val;
 503                 tp->rtt_seq = tp->snd_nxt;
 504         }
 505         val = tcp_metric_get_jiffies(tm, TCP_METRIC_RTTVAR);
 506         if (val > tp->mdev) {
 507                 tp->mdev = val;
 508                 tp->mdev_max = tp->rttvar = max(tp->mdev, tcp_rto_min(sk));
 509         }
 510         rcu_read_unlock();
 511
 512         tcp_set_rto(sk);
 513 reset:
 514         if (tp->srtt == 0) {
 515                 /* RFC6298: 5.7 We've failed to get a valid RTT sample from
 516                  * 3WHS. This is most likely due to retransmission,
 517                  * including spurious one. Reset the RTO back to 3secs
 518                  * from the more aggressive 1sec to avoid more spurious
 519                  * retransmission.
 520                  */
 521                 tp->mdev = tp->mdev_max = tp->rttvar = TCP_TIMEOUT_FALLBACK;
 522                 inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
 523         }
 524         /* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
 525          * retransmitted. In light of RFC6298 more aggressive 1sec
 526          * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
 527          * retransmission has occurred.
 528          */
 529         if (tp->total_retrans > 1)
 530                 tp->snd_cwnd = 1;
 531         else
 532                 tp->snd_cwnd = tcp_init_cwnd(tp, dst);
 533         tp->snd_cwnd_stamp = tcp_time_stamp;
 534 }
 535
 536 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, bool paws_check)
 537 {
 538         struct tcp_metrics_block *tm;
 539         bool ret;
 540
 541         if (!dst)
 542                 return false;
 543
 544         rcu_read_lock();
 545         tm = __tcp_get_metrics_req(req, dst);
 546         if (paws_check) {
 547                 if (tm &&
 548                     (u32)get_seconds() - tm->tcpm_ts_stamp < TCP_PAWS_MSL &&
 549                     (s32)(tm->tcpm_ts - req->ts_recent) > TCP_PAWS_WINDOW)
 550                         ret = false;
 551                 else
 552                         ret = true;
 553         } else {
 554                 if (tm && tcp_metric_get(tm, TCP_METRIC_RTT) && tm->tcpm_ts_stamp)
 555                         ret = true;
 556                 else
 557                         ret = false;
 558         }
 559         rcu_read_unlock();
 560
 561         return ret;
 562 }
 563 EXPORT_SYMBOL_GPL(tcp_peer_is_proven);
 564
 565 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst)
 566 {
 567         struct tcp_metrics_block *tm;
 568
 569         rcu_read_lock();
 570         tm = tcp_get_metrics(sk, dst, true);
 571         if (tm) {
 572                 struct tcp_sock *tp = tcp_sk(sk);
 573
 574                 if ((u32)get_seconds() - tm->tcpm_ts_stamp <= TCP_PAWS_MSL) {
 575                         tp->rx_opt.ts_recent_stamp = tm->tcpm_ts_stamp;
 576                         tp->rx_opt.ts_recent = tm->tcpm_ts;
 577                 }
 578         }
 579         rcu_read_unlock();
 580 }
 581 EXPORT_SYMBOL_GPL(tcp_fetch_timewait_stamp);
 582
 583 /* VJ's idea. Save last timestamp seen from this destination and hold
 584  * it at least for normal timewait interval to use for duplicate
 585  * segment detection in subsequent connections, before they enter
 586  * synchronized state.
 587  */
 588 bool tcp_remember_stamp(struct sock *sk)
 589 {
 590         struct dst_entry *dst = __sk_dst_get(sk);
 591         bool ret = false;
 592
 593         if (dst) {
 594                 struct tcp_metrics_block *tm;
 595
 596                 rcu_read_lock();
 597                 tm = tcp_get_metrics(sk, dst, true);
 598                 if (tm) {
 599                         struct tcp_sock *tp = tcp_sk(sk);
 600
 601                         if ((s32)(tm->tcpm_ts - tp->rx_opt.ts_recent) <= 0 ||
 602                             ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 603                              tm->tcpm_ts_stamp <= (u32)tp->rx_opt.ts_recent_stamp)) {
 604                                 tm->tcpm_ts_stamp = (u32)tp->rx_opt.ts_recent_stamp;
 605                                 tm->tcpm_ts = tp->rx_opt.ts_recent;
 606                         }
 607                         ret = true;
 608                 }
 609                 rcu_read_unlock();
 610         }
 611         return ret;
 612 }
 613
 614 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw)
 615 {
 616         struct tcp_metrics_block *tm;
 617         bool ret = false;
 618
 619         rcu_read_lock();
 620         tm = __tcp_get_metrics_tw(tw);
 621         if (tm) {
 622                 const struct tcp_timewait_sock *tcptw;
 623                 struct sock *sk = (struct sock *) tw;
 624
 625                 tcptw = tcp_twsk(sk);
 626                 if ((s32)(tm->tcpm_ts - tcptw->tw_ts_recent) <= 0 ||
 627                     ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 628                      tm->tcpm_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) {
 629                         tm->tcpm_ts_stamp = (u32)tcptw->tw_ts_recent_stamp;
 630                         tm->tcpm_ts        = tcptw->tw_ts_recent;
 631                 }
 632                 ret = true;
 633         }
 634         rcu_read_unlock();
 635
 636         return ret;
 637 }
 638
 639 static DEFINE_SEQLOCK(fastopen_seqlock);
 640
 641 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
 642                             struct tcp_fastopen_cookie *cookie,
 643                             int *syn_loss, unsigned long *last_syn_loss)
 644 {
 645         struct tcp_metrics_block *tm;
 646
 647         rcu_read_lock();
 648         tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
 649         if (tm) {
 650                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 651                 unsigned int seq;
 652
 653                 do {
 654                         seq = read_seqbegin(&fastopen_seqlock);
 655                         if (tfom->mss)
 656                                 *mss = tfom->mss;
 657                         *cookie = tfom->cookie;
 658                         *syn_loss = tfom->syn_loss;
 659                         *last_syn_loss = *syn_loss ? tfom->last_syn_loss : 0;
 660                 } while (read_seqretry(&fastopen_seqlock, seq));
 661         }
 662         rcu_read_unlock();
 663 }
 664
 665 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
 666                             struct tcp_fastopen_cookie *cookie, bool syn_lost)
 667 {
 668         struct tcp_metrics_block *tm;
 669
 670         rcu_read_lock();
 671         tm = tcp_get_metrics(sk, __sk_dst_get(sk), true);
 672         if (tm) {
 673                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 674
 675                 write_seqlock_bh(&fastopen_seqlock);
 676                 tfom->mss = mss;
 677                 if (cookie->len > 0)
 678                         tfom->cookie = *cookie;
 679                 if (syn_lost) {
 680                         ++tfom->syn_loss;
 681                         tfom->last_syn_loss = jiffies;
 682                 } else
 683                         tfom->syn_loss = 0;
 684                 write_sequnlock_bh(&fastopen_seqlock);
 685         }
 686         rcu_read_unlock();
 687 }
 688
 689 static struct genl_family tcp_metrics_nl_family = {
 690         .id             = GENL_ID_GENERATE,
 691         .hdrsize        = 0,
 692         .name           = TCP_METRICS_GENL_NAME,
 693         .version        = TCP_METRICS_GENL_VERSION,
 694         .maxattr        = TCP_METRICS_ATTR_MAX,
 695         .netnsok        = true,
 696 };
 697
 698 static struct nla_policy tcp_metrics_nl_policy[TCP_METRICS_ATTR_MAX + 1] = {
 699         [TCP_METRICS_ATTR_ADDR_IPV4]    = { .type = NLA_U32, },
 700         [TCP_METRICS_ATTR_ADDR_IPV6]    = { .type = NLA_BINARY,
 701                                             .len = sizeof(struct in6_addr), },
 702         /* Following attributes are not received for GET/DEL,
 703          * we keep them for reference
 704          */
 705 #if 0
 706         [TCP_METRICS_ATTR_AGE]          = { .type = NLA_MSECS, },
 707         [TCP_METRICS_ATTR_TW_TSVAL]     = { .type = NLA_U32, },
 708         [TCP_METRICS_ATTR_TW_TS_STAMP]  = { .type = NLA_S32, },
 709         [TCP_METRICS_ATTR_VALS]         = { .type = NLA_NESTED, },
 710         [TCP_METRICS_ATTR_FOPEN_MSS]    = { .type = NLA_U16, },
 711         [TCP_METRICS_ATTR_FOPEN_SYN_DROPS]      = { .type = NLA_U16, },
 712         [TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS]    = { .type = NLA_MSECS, },
 713         [TCP_METRICS_ATTR_FOPEN_COOKIE] = { .type = NLA_BINARY,
 714                                             .len = TCP_FASTOPEN_COOKIE_MAX, },
 715 #endif
 716 };
 717
 718 /* Add attributes, caller cancels its header on failure */
 719 static int tcp_metrics_fill_info(struct sk_buff *msg,
 720                                  struct tcp_metrics_block *tm)
 721 {
 722         struct nlattr *nest;
 723         int i;
 724
 725         switch (tm->tcpm_addr.family) {
 726         case AF_INET:
 727                 if (nla_put_be32(msg, TCP_METRICS_ATTR_ADDR_IPV4,
 728                                 tm->tcpm_addr.addr.a4) < 0)
 729                         goto nla_put_failure;
 730                 break;
 731         case AF_INET6:
 732                 if (nla_put(msg, TCP_METRICS_ATTR_ADDR_IPV6, 16,
 733                             tm->tcpm_addr.addr.a6) < 0)
 734                         goto nla_put_failure;
 735                 break;
 736         default:
 737                 return -EAFNOSUPPORT;
 738         }
 739
 740         if (nla_put_msecs(msg, TCP_METRICS_ATTR_AGE,
 741                           jiffies - tm->tcpm_stamp) < 0)
 742                 goto nla_put_failure;
 743         if (tm->tcpm_ts_stamp) {
 744                 if (nla_put_s32(msg, TCP_METRICS_ATTR_TW_TS_STAMP,
 745                                 (s32) (get_seconds() - tm->tcpm_ts_stamp)) < 0)
 746                         goto nla_put_failure;
 747                 if (nla_put_u32(msg, TCP_METRICS_ATTR_TW_TSVAL,
 748                                 tm->tcpm_ts) < 0)
 749                         goto nla_put_failure;
 750         }
 751
 752         {
 753                 int n = 0;
 754
 755                 nest = nla_nest_start(msg, TCP_METRICS_ATTR_VALS);
 756                 if (!nest)
 757                         goto nla_put_failure;
 758                 for (i = 0; i < TCP_METRIC_MAX + 1; i++) {
 759                         if (!tm->tcpm_vals[i])
 760                                 continue;
 761                         if (nla_put_u32(msg, i + 1, tm->tcpm_vals[i]) < 0)
 762                                 goto nla_put_failure;
 763                         n++;
 764                 }
 765                 if (n)
 766                         nla_nest_end(msg, nest);
 767                 else
 768                         nla_nest_cancel(msg, nest);
 769         }
 770
 771         {
 772                 struct tcp_fastopen_metrics tfom_copy[1], *tfom;
 773                 unsigned int seq;
 774
 775                 do {
 776                         seq = read_seqbegin(&fastopen_seqlock);
 777                         tfom_copy[0] = tm->tcpm_fastopen;
 778                 } while (read_seqretry(&fastopen_seqlock, seq));
 779
 780                 tfom = tfom_copy;
 781                 if (tfom->mss &&
 782                     nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_MSS,
 783                                 tfom->mss) < 0)
 784                         goto nla_put_failure;
 785                 if (tfom->syn_loss &&
 786                     (nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROPS,
 787                                 tfom->syn_loss) < 0 ||
 788                      nla_put_msecs(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS,
 789                                 jiffies - tfom->last_syn_loss) < 0))
 790                         goto nla_put_failure;
 791                 if (tfom->cookie.len > 0 &&
 792                     nla_put(msg, TCP_METRICS_ATTR_FOPEN_COOKIE,
 793                             tfom->cookie.len, tfom->cookie.val) < 0)
 794                         goto nla_put_failure;
 795         }
 796
 797         return 0;
 798
 799 nla_put_failure:
 800         return -EMSGSIZE;
 801 }
 802
 803 static int tcp_metrics_dump_info(struct sk_buff *skb,
 804                                  struct netlink_callback *cb,
 805                                  struct tcp_metrics_block *tm)
 806 {
 807         void *hdr;
 808
 809         hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
 810                           &tcp_metrics_nl_family, NLM_F_MULTI,
 811                           TCP_METRICS_CMD_GET);
 812         if (!hdr)
 813                 return -EMSGSIZE;
 814
 815         if (tcp_metrics_fill_info(skb, tm) < 0)
 816                 goto nla_put_failure;
 817
 818         return genlmsg_end(skb, hdr);
 819
 820 nla_put_failure:
 821         genlmsg_cancel(skb, hdr);
 822         return -EMSGSIZE;
 823 }
 824
 825 static int tcp_metrics_nl_dump(struct sk_buff *skb,
 826                                struct netlink_callback *cb)
 827 {
 828         struct net *net = sock_net(skb->sk);
 829         unsigned int max_rows = 1U << net->ipv4.tcp_metrics_hash_log;
 830         unsigned int row, s_row = cb->args[0];
 831         int s_col = cb->args[1], col = s_col;
 832
 833         for (row = s_row; row < max_rows; row++, s_col = 0) {
 834                 struct tcp_metrics_block *tm;
 835                 struct tcpm_hash_bucket *hb = net->ipv4.tcp_metrics_hash + row;
 836
 837                 rcu_read_lock();
 838                 for (col = 0, tm = rcu_dereference(hb->chain); tm;
 839                      tm = rcu_dereference(tm->tcpm_next), col++) {
 840                         if (col < s_col)
 841                                 continue;
 842                         if (tcp_metrics_dump_info(skb, cb, tm) < 0) {
 843                                 rcu_read_unlock();
 844                                 goto done;
 845                         }
 846                 }
 847                 rcu_read_unlock();
 848         }
 849
 850 done:
 851         cb->args[0] = row;
 852         cb->args[1] = col;
 853         return skb->len;
 854 }
 855
 856 static int parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 857                          unsigned int *hash, int optional)
 858 {
 859         struct nlattr *a;
 860
 861         a = info->attrs[TCP_METRICS_ATTR_ADDR_IPV4];
 862         if (a) {
 863                 addr->family = AF_INET;
 864                 addr->addr.a4 = nla_get_be32(a);
 865                 *hash = (__force unsigned int) addr->addr.a4;
 866                 return 0;
 867         }
 868         a = info->attrs[TCP_METRICS_ATTR_ADDR_IPV6];
 869         if (a) {
 870                 if (nla_len(a) != sizeof(struct in6_addr))
 871                         return -EINVAL;
 872                 addr->family = AF_INET6;
 873                 memcpy(addr->addr.a6, nla_data(a), sizeof(addr->addr.a6));
 874                 *hash = ipv6_addr_hash((struct in6_addr *) addr->addr.a6);
 875                 return 0;
 876         }
 877         return optional ? 1 : -EAFNOSUPPORT;
 878 }
 879
 880 static int tcp_metrics_nl_cmd_get(struct sk_buff *skb, struct genl_info *info)
 881 {
 882         struct tcp_metrics_block *tm;
 883         struct inetpeer_addr addr;
 884         unsigned int hash;
 885         struct sk_buff *msg;
 886         struct net *net = genl_info_net(info);
 887         void *reply;
 888         int ret;
 889
 890         ret = parse_nl_addr(info, &addr, &hash, 0);
 891         if (ret < 0)
 892                 return ret;
 893
 894         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 895         if (!msg)
 896                 return -ENOMEM;
 897
 898         reply = genlmsg_put_reply(msg, info, &tcp_metrics_nl_family, 0,
 899                                   info->genlhdr->cmd);
 900         if (!reply)
 901                 goto nla_put_failure;
 902
 903         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 904         ret = -ESRCH;
 905         rcu_read_lock();
 906         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 907              tm = rcu_dereference(tm->tcpm_next)) {
 908                 if (addr_same(&tm->tcpm_addr, &addr)) {
 909                         ret = tcp_metrics_fill_info(msg, tm);
 910                         break;
 911                 }
 912         }
 913         rcu_read_unlock();
 914         if (ret < 0)
 915                 goto out_free;
 916
 917         genlmsg_end(msg, reply);
 918         return genlmsg_reply(msg, info);
 919
 920 nla_put_failure:
 921         ret = -EMSGSIZE;
 922
 923 out_free:
 924         nlmsg_free(msg);
 925         return ret;
 926 }
 927
 928 #define deref_locked_genl(p)    \
 929         rcu_dereference_protected(p, lockdep_genl_is_held() && \
 930                                      lockdep_is_held(&tcp_metrics_lock))
 931
 932 #define deref_genl(p)   rcu_dereference_protected(p, lockdep_genl_is_held())
 933
 934 static int tcp_metrics_flush_all(struct net *net)
 935 {
 936         unsigned int max_rows = 1U << net->ipv4.tcp_metrics_hash_log;
 937         struct tcpm_hash_bucket *hb = net->ipv4.tcp_metrics_hash;
 938         struct tcp_metrics_block *tm;
 939         unsigned int row;
 940
 941         for (row = 0; row < max_rows; row++, hb++) {
 942                 spin_lock_bh(&tcp_metrics_lock);
 943                 tm = deref_locked_genl(hb->chain);
 944                 if (tm)
 945                         hb->chain = NULL;
 946                 spin_unlock_bh(&tcp_metrics_lock);
 947                 while (tm) {
 948                         struct tcp_metrics_block *next;
 949
 950                         next = deref_genl(tm->tcpm_next);
 951                         kfree_rcu(tm, rcu_head);
 952                         tm = next;
 953                 }
 954         }
 955         return 0;
 956 }
 957
 958 static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info)
 959 {
 960         struct tcpm_hash_bucket *hb;
 961         struct tcp_metrics_block *tm;
 962         struct tcp_metrics_block __rcu **pp;
 963         struct inetpeer_addr addr;
 964         unsigned int hash;
 965         struct net *net = genl_info_net(info);
 966         int ret;
 967
 968         ret = parse_nl_addr(info, &addr, &hash, 1);
 969         if (ret < 0)
 970                 return ret;
 971         if (ret > 0)
 972                 return tcp_metrics_flush_all(net);
 973
 974         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 975         hb = net->ipv4.tcp_metrics_hash + hash;
 976         pp = &hb->chain;
 977         spin_lock_bh(&tcp_metrics_lock);
 978         for (tm = deref_locked_genl(*pp); tm;
 979              pp = &tm->tcpm_next, tm = deref_locked_genl(*pp)) {
 980                 if (addr_same(&tm->tcpm_addr, &addr)) {
 981                         *pp = tm->tcpm_next;
 982                         break;
 983                 }
 984         }
 985         spin_unlock_bh(&tcp_metrics_lock);
 986         if (!tm)
 987                 return -ESRCH;
 988         kfree_rcu(tm, rcu_head);
 989         return 0;
 990 }
 991
 992 static struct genl_ops tcp_metrics_nl_ops[] = {
 993         {
 994                 .cmd = TCP_METRICS_CMD_GET,
 995                 .doit = tcp_metrics_nl_cmd_get,
 996                 .dumpit = tcp_metrics_nl_dump,
 997                 .policy = tcp_metrics_nl_policy,
 998                 .flags = GENL_ADMIN_PERM,
 999         },
1000         {
1001                 .cmd = TCP_METRICS_CMD_DEL,
1002                 .doit = tcp_metrics_nl_cmd_del,
1003                 .policy = tcp_metrics_nl_policy,
1004                 .flags = GENL_ADMIN_PERM,
1005         },
1006 };
1007
1008 static unsigned int tcpmhash_entries;
1009 static int __init set_tcpmhash_entries(char *str)
1010 {
1011         ssize_t ret;
1012
1013         if (!str)
1014                 return 0;
1015
1016         ret = kstrtouint(str, 0, &tcpmhash_entries);
1017         if (ret)
1018                 return 0;
1019
1020         return 1;
1021 }
1022 __setup("tcpmhash_entries=", set_tcpmhash_entries);
1023
1024 static int __net_init tcp_net_metrics_init(struct net *net)
1025 {
1026         size_t size;
1027         unsigned int slots;
1028
1029         slots = tcpmhash_entries;
1030         if (!slots) {
1031                 if (totalram_pages >= 128 * 1024)
1032                         slots = 16 * 1024;
1033                 else
1034                         slots = 8 * 1024;
1035         }
1036
1037         net->ipv4.tcp_metrics_hash_log = order_base_2(slots);
1038         size = sizeof(struct tcpm_hash_bucket) << net->ipv4.tcp_metrics_hash_log;
1039
1040         net->ipv4.tcp_metrics_hash = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
1041         if (!net->ipv4.tcp_metrics_hash)
1042                 net->ipv4.tcp_metrics_hash = vzalloc(size);
1043
1044         if (!net->ipv4.tcp_metrics_hash)
1045                 return -ENOMEM;
1046
1047         return 0;
1048 }
1049
1050 static void __net_exit tcp_net_metrics_exit(struct net *net)
1051 {
1052         unsigned int i;
1053
1054         for (i = 0; i < (1U << net->ipv4.tcp_metrics_hash_log) ; i++) {
1055                 struct tcp_metrics_block *tm, *next;
1056
1057                 tm = rcu_dereference_protected(net->ipv4.tcp_metrics_hash[i].chain, 1);
1058                 while (tm) {
1059                         next = rcu_dereference_protected(tm->tcpm_next, 1);
1060                         kfree(tm);
1061                         tm = next;
1062                 }
1063         }
1064         if (is_vmalloc_addr(net->ipv4.tcp_metrics_hash))
1065                 vfree(net->ipv4.tcp_metrics_hash);
1066         else
1067                 kfree(net->ipv4.tcp_metrics_hash);
1068 }
1069
1070 static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
1071         .init   =       tcp_net_metrics_init,
1072         .exit   =       tcp_net_metrics_exit,
1073 };
1074
1075 void __init tcp_metrics_init(void)
1076 {
1077         int ret;
1078
1079         ret = register_pernet_subsys(&tcp_net_metrics_ops);
1080         if (ret < 0)
1081                 goto cleanup;
1082         ret = genl_register_family_with_ops(&tcp_metrics_nl_family,
1083                                             tcp_metrics_nl_ops,
1084                                             ARRAY_SIZE(tcp_metrics_nl_ops));
1085         if (ret < 0)
1086                 goto cleanup_subsys;
1087         return;
1088
1089 cleanup_subsys:
1090         unregister_pernet_subsys(&tcp_net_metrics_ops);
1091
1092 cleanup:
1093         return;
1094 }