Pileus Git - ~andy/linux/blob - 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)->ir_rmt_addr;
 219                 hash = (__force unsigned int) addr.addr.a4;
 220                 break;
 221 #if IS_ENABLED(CONFIG_IPV6)
 222         case AF_INET6:
 223                 *(struct in6_addr *)addr.addr.a6 = inet_rsk(req)->ir_v6_rmt_addr;
 224                 hash = ipv6_addr_hash(&inet_rsk(req)->ir_v6_rmt_addr);
 225                 break;
 226 #endif
 227         default:
 228                 return NULL;
 229         }
 230
 231         net = dev_net(dst->dev);
 232         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 233
 234         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 235              tm = rcu_dereference(tm->tcpm_next)) {
 236                 if (addr_same(&tm->tcpm_addr, &addr))
 237                         break;
 238         }
 239         tcpm_check_stamp(tm, dst);
 240         return tm;
 241 }
 242
 243 static struct tcp_metrics_block *__tcp_get_metrics_tw(struct inet_timewait_sock *tw)
 244 {
 245         struct tcp_metrics_block *tm;
 246         struct inetpeer_addr addr;
 247         unsigned int hash;
 248         struct net *net;
 249
 250         addr.family = tw->tw_family;
 251         switch (addr.family) {
 252         case AF_INET:
 253                 addr.addr.a4 = tw->tw_daddr;
 254                 hash = (__force unsigned int) addr.addr.a4;
 255                 break;
 256 #if IS_ENABLED(CONFIG_IPV6)
 257         case AF_INET6:
 258                 *(struct in6_addr *)addr.addr.a6 = tw->tw_v6_daddr;
 259                 hash = ipv6_addr_hash(&tw->tw_v6_daddr);
 260                 break;
 261 #endif
 262         default:
 263                 return NULL;
 264         }
 265
 266         net = twsk_net(tw);
 267         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 268
 269         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 270              tm = rcu_dereference(tm->tcpm_next)) {
 271                 if (addr_same(&tm->tcpm_addr, &addr))
 272                         break;
 273         }
 274         return tm;
 275 }
 276
 277 static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
 278                                                  struct dst_entry *dst,
 279                                                  bool create)
 280 {
 281         struct tcp_metrics_block *tm;
 282         struct inetpeer_addr addr;
 283         unsigned int hash;
 284         struct net *net;
 285         bool reclaim;
 286
 287         addr.family = sk->sk_family;
 288         switch (addr.family) {
 289         case AF_INET:
 290                 addr.addr.a4 = inet_sk(sk)->inet_daddr;
 291                 hash = (__force unsigned int) addr.addr.a4;
 292                 break;
 293 #if IS_ENABLED(CONFIG_IPV6)
 294         case AF_INET6:
 295                 *(struct in6_addr *)addr.addr.a6 = sk->sk_v6_daddr;
 296                 hash = ipv6_addr_hash(&sk->sk_v6_daddr);
 297                 break;
 298 #endif
 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, crtt = 0; /* cached RTT scaled by 8 */
 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         crtt = tcp_metric_get_jiffies(tm, TCP_METRIC_RTT);
 486         rcu_read_unlock();
 487 reset:
 488         /* The initial RTT measurement from the SYN/SYN-ACK is not ideal
 489          * to seed the RTO for later data packets because SYN packets are
 490          * small. Use the per-dst cached values to seed the RTO but keep
 491          * the RTT estimator variables intact (e.g., srtt, mdev, rttvar).
 492          * Later the RTO will be updated immediately upon obtaining the first
 493          * data RTT sample (tcp_rtt_estimator()). Hence the cached RTT only
 494          * influences the first RTO but not later RTT estimation.
 495          *
 496          * But if RTT is not available from the SYN (due to retransmits or
 497          * syn cookies) or the cache, force a conservative 3secs timeout.
 498          *
 499          * A bit of theory. RTT is time passed after "normal" sized packet
 500          * is sent until it is ACKed. In normal circumstances sending small
 501          * packets force peer to delay ACKs and calculation is correct too.
 502          * The algorithm is adaptive and, provided we follow specs, it
 503          * NEVER underestimate RTT. BUT! If peer tries to make some clever
 504          * tricks sort of "quick acks" for time long enough to decrease RTT
 505          * to low value, and then abruptly stops to do it and starts to delay
 506          * ACKs, wait for troubles.
 507          */
 508         if (crtt > tp->srtt) {
 509                 /* Set RTO like tcp_rtt_estimator(), but from cached RTT. */
 510                 crtt >>= 3;
 511                 inet_csk(sk)->icsk_rto = crtt + max(2 * crtt, tcp_rto_min(sk));
 512         } else if (tp->srtt == 0) {
 513                 /* RFC6298: 5.7 We've failed to get a valid RTT sample from
 514                  * 3WHS. This is most likely due to retransmission,
 515                  * including spurious one. Reset the RTO back to 3secs
 516                  * from the more aggressive 1sec to avoid more spurious
 517                  * retransmission.
 518                  */
 519                 tp->mdev = tp->mdev_max = tp->rttvar = TCP_TIMEOUT_FALLBACK;
 520                 inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
 521         }
 522         /* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
 523          * retransmitted. In light of RFC6298 more aggressive 1sec
 524          * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
 525          * retransmission has occurred.
 526          */
 527         if (tp->total_retrans > 1)
 528                 tp->snd_cwnd = 1;
 529         else
 530                 tp->snd_cwnd = tcp_init_cwnd(tp, dst);
 531         tp->snd_cwnd_stamp = tcp_time_stamp;
 532 }
 533
 534 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, bool paws_check)
 535 {
 536         struct tcp_metrics_block *tm;
 537         bool ret;
 538
 539         if (!dst)
 540                 return false;
 541
 542         rcu_read_lock();
 543         tm = __tcp_get_metrics_req(req, dst);
 544         if (paws_check) {
 545                 if (tm &&
 546                     (u32)get_seconds() - tm->tcpm_ts_stamp < TCP_PAWS_MSL &&
 547                     (s32)(tm->tcpm_ts - req->ts_recent) > TCP_PAWS_WINDOW)
 548                         ret = false;
 549                 else
 550                         ret = true;
 551         } else {
 552                 if (tm && tcp_metric_get(tm, TCP_METRIC_RTT) && tm->tcpm_ts_stamp)
 553                         ret = true;
 554                 else
 555                         ret = false;
 556         }
 557         rcu_read_unlock();
 558
 559         return ret;
 560 }
 561 EXPORT_SYMBOL_GPL(tcp_peer_is_proven);
 562
 563 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst)
 564 {
 565         struct tcp_metrics_block *tm;
 566
 567         rcu_read_lock();
 568         tm = tcp_get_metrics(sk, dst, true);
 569         if (tm) {
 570                 struct tcp_sock *tp = tcp_sk(sk);
 571
 572                 if ((u32)get_seconds() - tm->tcpm_ts_stamp <= TCP_PAWS_MSL) {
 573                         tp->rx_opt.ts_recent_stamp = tm->tcpm_ts_stamp;
 574                         tp->rx_opt.ts_recent = tm->tcpm_ts;
 575                 }
 576         }
 577         rcu_read_unlock();
 578 }
 579 EXPORT_SYMBOL_GPL(tcp_fetch_timewait_stamp);
 580
 581 /* VJ's idea. Save last timestamp seen from this destination and hold
 582  * it at least for normal timewait interval to use for duplicate
 583  * segment detection in subsequent connections, before they enter
 584  * synchronized state.
 585  */
 586 bool tcp_remember_stamp(struct sock *sk)
 587 {
 588         struct dst_entry *dst = __sk_dst_get(sk);
 589         bool ret = false;
 590
 591         if (dst) {
 592                 struct tcp_metrics_block *tm;
 593
 594                 rcu_read_lock();
 595                 tm = tcp_get_metrics(sk, dst, true);
 596                 if (tm) {
 597                         struct tcp_sock *tp = tcp_sk(sk);
 598
 599                         if ((s32)(tm->tcpm_ts - tp->rx_opt.ts_recent) <= 0 ||
 600                             ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 601                              tm->tcpm_ts_stamp <= (u32)tp->rx_opt.ts_recent_stamp)) {
 602                                 tm->tcpm_ts_stamp = (u32)tp->rx_opt.ts_recent_stamp;
 603                                 tm->tcpm_ts = tp->rx_opt.ts_recent;
 604                         }
 605                         ret = true;
 606                 }
 607                 rcu_read_unlock();
 608         }
 609         return ret;
 610 }
 611
 612 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw)
 613 {
 614         struct tcp_metrics_block *tm;
 615         bool ret = false;
 616
 617         rcu_read_lock();
 618         tm = __tcp_get_metrics_tw(tw);
 619         if (tm) {
 620                 const struct tcp_timewait_sock *tcptw;
 621                 struct sock *sk = (struct sock *) tw;
 622
 623                 tcptw = tcp_twsk(sk);
 624                 if ((s32)(tm->tcpm_ts - tcptw->tw_ts_recent) <= 0 ||
 625                     ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 626                      tm->tcpm_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) {
 627                         tm->tcpm_ts_stamp = (u32)tcptw->tw_ts_recent_stamp;
 628                         tm->tcpm_ts        = tcptw->tw_ts_recent;
 629                 }
 630                 ret = true;
 631         }
 632         rcu_read_unlock();
 633
 634         return ret;
 635 }
 636
 637 static DEFINE_SEQLOCK(fastopen_seqlock);
 638
 639 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
 640                             struct tcp_fastopen_cookie *cookie,
 641                             int *syn_loss, unsigned long *last_syn_loss)
 642 {
 643         struct tcp_metrics_block *tm;
 644
 645         rcu_read_lock();
 646         tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
 647         if (tm) {
 648                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 649                 unsigned int seq;
 650
 651                 do {
 652                         seq = read_seqbegin(&fastopen_seqlock);
 653                         if (tfom->mss)
 654                                 *mss = tfom->mss;
 655                         *cookie = tfom->cookie;
 656                         *syn_loss = tfom->syn_loss;
 657                         *last_syn_loss = *syn_loss ? tfom->last_syn_loss : 0;
 658                 } while (read_seqretry(&fastopen_seqlock, seq));
 659         }
 660         rcu_read_unlock();
 661 }
 662
 663 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
 664                             struct tcp_fastopen_cookie *cookie, bool syn_lost)
 665 {
 666         struct tcp_metrics_block *tm;
 667
 668         rcu_read_lock();
 669         tm = tcp_get_metrics(sk, __sk_dst_get(sk), true);
 670         if (tm) {
 671                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 672
 673                 write_seqlock_bh(&fastopen_seqlock);
 674                 tfom->mss = mss;
 675                 if (cookie->len > 0)
 676                         tfom->cookie = *cookie;
 677                 if (syn_lost) {
 678                         ++tfom->syn_loss;
 679                         tfom->last_syn_loss = jiffies;
 680                 } else
 681                         tfom->syn_loss = 0;
 682                 write_sequnlock_bh(&fastopen_seqlock);
 683         }
 684         rcu_read_unlock();
 685 }
 686
 687 static struct genl_family tcp_metrics_nl_family = {
 688         .id             = GENL_ID_GENERATE,
 689         .hdrsize        = 0,
 690         .name           = TCP_METRICS_GENL_NAME,
 691         .version        = TCP_METRICS_GENL_VERSION,
 692         .maxattr        = TCP_METRICS_ATTR_MAX,
 693         .netnsok        = true,
 694 };
 695
 696 static struct nla_policy tcp_metrics_nl_policy[TCP_METRICS_ATTR_MAX + 1] = {
 697         [TCP_METRICS_ATTR_ADDR_IPV4]    = { .type = NLA_U32, },
 698         [TCP_METRICS_ATTR_ADDR_IPV6]    = { .type = NLA_BINARY,
 699                                             .len = sizeof(struct in6_addr), },
 700         /* Following attributes are not received for GET/DEL,
 701          * we keep them for reference
 702          */
 703 #if 0
 704         [TCP_METRICS_ATTR_AGE]          = { .type = NLA_MSECS, },
 705         [TCP_METRICS_ATTR_TW_TSVAL]     = { .type = NLA_U32, },
 706         [TCP_METRICS_ATTR_TW_TS_STAMP]  = { .type = NLA_S32, },
 707         [TCP_METRICS_ATTR_VALS]         = { .type = NLA_NESTED, },
 708         [TCP_METRICS_ATTR_FOPEN_MSS]    = { .type = NLA_U16, },
 709         [TCP_METRICS_ATTR_FOPEN_SYN_DROPS]      = { .type = NLA_U16, },
 710         [TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS]    = { .type = NLA_MSECS, },
 711         [TCP_METRICS_ATTR_FOPEN_COOKIE] = { .type = NLA_BINARY,
 712                                             .len = TCP_FASTOPEN_COOKIE_MAX, },
 713 #endif
 714 };
 715
 716 /* Add attributes, caller cancels its header on failure */
 717 static int tcp_metrics_fill_info(struct sk_buff *msg,
 718                                  struct tcp_metrics_block *tm)
 719 {
 720         struct nlattr *nest;
 721         int i;
 722
 723         switch (tm->tcpm_addr.family) {
 724         case AF_INET:
 725                 if (nla_put_be32(msg, TCP_METRICS_ATTR_ADDR_IPV4,
 726                                 tm->tcpm_addr.addr.a4) < 0)
 727                         goto nla_put_failure;
 728                 break;
 729         case AF_INET6:
 730                 if (nla_put(msg, TCP_METRICS_ATTR_ADDR_IPV6, 16,
 731                             tm->tcpm_addr.addr.a6) < 0)
 732                         goto nla_put_failure;
 733                 break;
 734         default:
 735                 return -EAFNOSUPPORT;
 736         }
 737
 738         if (nla_put_msecs(msg, TCP_METRICS_ATTR_AGE,
 739                           jiffies - tm->tcpm_stamp) < 0)
 740                 goto nla_put_failure;
 741         if (tm->tcpm_ts_stamp) {
 742                 if (nla_put_s32(msg, TCP_METRICS_ATTR_TW_TS_STAMP,
 743                                 (s32) (get_seconds() - tm->tcpm_ts_stamp)) < 0)
 744                         goto nla_put_failure;
 745                 if (nla_put_u32(msg, TCP_METRICS_ATTR_TW_TSVAL,
 746                                 tm->tcpm_ts) < 0)
 747                         goto nla_put_failure;
 748         }
 749
 750         {
 751                 int n = 0;
 752
 753                 nest = nla_nest_start(msg, TCP_METRICS_ATTR_VALS);
 754                 if (!nest)
 755                         goto nla_put_failure;
 756                 for (i = 0; i < TCP_METRIC_MAX + 1; i++) {
 757                         if (!tm->tcpm_vals[i])
 758                                 continue;
 759                         if (nla_put_u32(msg, i + 1, tm->tcpm_vals[i]) < 0)
 760                                 goto nla_put_failure;
 761                         n++;
 762                 }
 763                 if (n)
 764                         nla_nest_end(msg, nest);
 765                 else
 766                         nla_nest_cancel(msg, nest);
 767         }
 768
 769         {
 770                 struct tcp_fastopen_metrics tfom_copy[1], *tfom;
 771                 unsigned int seq;
 772
 773                 do {
 774                         seq = read_seqbegin(&fastopen_seqlock);
 775                         tfom_copy[0] = tm->tcpm_fastopen;
 776                 } while (read_seqretry(&fastopen_seqlock, seq));
 777
 778                 tfom = tfom_copy;
 779                 if (tfom->mss &&
 780                     nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_MSS,
 781                                 tfom->mss) < 0)
 782                         goto nla_put_failure;
 783                 if (tfom->syn_loss &&
 784                     (nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROPS,
 785                                 tfom->syn_loss) < 0 ||
 786                      nla_put_msecs(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS,
 787                                 jiffies - tfom->last_syn_loss) < 0))
 788                         goto nla_put_failure;
 789                 if (tfom->cookie.len > 0 &&
 790                     nla_put(msg, TCP_METRICS_ATTR_FOPEN_COOKIE,
 791                             tfom->cookie.len, tfom->cookie.val) < 0)
 792                         goto nla_put_failure;
 793         }
 794
 795         return 0;
 796
 797 nla_put_failure:
 798         return -EMSGSIZE;
 799 }
 800
 801 static int tcp_metrics_dump_info(struct sk_buff *skb,
 802                                  struct netlink_callback *cb,
 803                                  struct tcp_metrics_block *tm)
 804 {
 805         void *hdr;
 806
 807         hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
 808                           &tcp_metrics_nl_family, NLM_F_MULTI,
 809                           TCP_METRICS_CMD_GET);
 810         if (!hdr)
 811                 return -EMSGSIZE;
 812
 813         if (tcp_metrics_fill_info(skb, tm) < 0)
 814                 goto nla_put_failure;
 815
 816         return genlmsg_end(skb, hdr);
 817
 818 nla_put_failure:
 819         genlmsg_cancel(skb, hdr);
 820         return -EMSGSIZE;
 821 }
 822
 823 static int tcp_metrics_nl_dump(struct sk_buff *skb,
 824                                struct netlink_callback *cb)
 825 {
 826         struct net *net = sock_net(skb->sk);
 827         unsigned int max_rows = 1U << net->ipv4.tcp_metrics_hash_log;
 828         unsigned int row, s_row = cb->args[0];
 829         int s_col = cb->args[1], col = s_col;
 830
 831         for (row = s_row; row < max_rows; row++, s_col = 0) {
 832                 struct tcp_metrics_block *tm;
 833                 struct tcpm_hash_bucket *hb = net->ipv4.tcp_metrics_hash + row;
 834
 835                 rcu_read_lock();
 836                 for (col = 0, tm = rcu_dereference(hb->chain); tm;
 837                      tm = rcu_dereference(tm->tcpm_next), col++) {
 838                         if (col < s_col)
 839                                 continue;
 840                         if (tcp_metrics_dump_info(skb, cb, tm) < 0) {
 841                                 rcu_read_unlock();
 842                                 goto done;
 843                         }
 844                 }
 845                 rcu_read_unlock();
 846         }
 847
 848 done:
 849         cb->args[0] = row;
 850         cb->args[1] = col;
 851         return skb->len;
 852 }
 853
 854 static int parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 855                          unsigned int *hash, int optional)
 856 {
 857         struct nlattr *a;
 858
 859         a = info->attrs[TCP_METRICS_ATTR_ADDR_IPV4];
 860         if (a) {
 861                 addr->family = AF_INET;
 862                 addr->addr.a4 = nla_get_be32(a);
 863                 *hash = (__force unsigned int) addr->addr.a4;
 864                 return 0;
 865         }
 866         a = info->attrs[TCP_METRICS_ATTR_ADDR_IPV6];
 867         if (a) {
 868                 if (nla_len(a) != sizeof(struct in6_addr))
 869                         return -EINVAL;
 870                 addr->family = AF_INET6;
 871                 memcpy(addr->addr.a6, nla_data(a), sizeof(addr->addr.a6));
 872                 *hash = ipv6_addr_hash((struct in6_addr *) addr->addr.a6);
 873                 return 0;
 874         }
 875         return optional ? 1 : -EAFNOSUPPORT;
 876 }
 877
 878 static int tcp_metrics_nl_cmd_get(struct sk_buff *skb, struct genl_info *info)
 879 {
 880         struct tcp_metrics_block *tm;
 881         struct inetpeer_addr addr;
 882         unsigned int hash;
 883         struct sk_buff *msg;
 884         struct net *net = genl_info_net(info);
 885         void *reply;
 886         int ret;
 887
 888         ret = parse_nl_addr(info, &addr, &hash, 0);
 889         if (ret < 0)
 890                 return ret;
 891
 892         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 893         if (!msg)
 894                 return -ENOMEM;
 895
 896         reply = genlmsg_put_reply(msg, info, &tcp_metrics_nl_family, 0,
 897                                   info->genlhdr->cmd);
 898         if (!reply)
 899                 goto nla_put_failure;
 900
 901         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 902         ret = -ESRCH;
 903         rcu_read_lock();
 904         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 905              tm = rcu_dereference(tm->tcpm_next)) {
 906                 if (addr_same(&tm->tcpm_addr, &addr)) {
 907                         ret = tcp_metrics_fill_info(msg, tm);
 908                         break;
 909                 }
 910         }
 911         rcu_read_unlock();
 912         if (ret < 0)
 913                 goto out_free;
 914
 915         genlmsg_end(msg, reply);
 916         return genlmsg_reply(msg, info);
 917
 918 nla_put_failure:
 919         ret = -EMSGSIZE;
 920
 921 out_free:
 922         nlmsg_free(msg);
 923         return ret;
 924 }
 925
 926 #define deref_locked_genl(p)    \
 927         rcu_dereference_protected(p, lockdep_genl_is_held() && \
 928                                      lockdep_is_held(&tcp_metrics_lock))
 929
 930 #define deref_genl(p)   rcu_dereference_protected(p, lockdep_genl_is_held())
 931
 932 static int tcp_metrics_flush_all(struct net *net)
 933 {
 934         unsigned int max_rows = 1U << net->ipv4.tcp_metrics_hash_log;
 935         struct tcpm_hash_bucket *hb = net->ipv4.tcp_metrics_hash;
 936         struct tcp_metrics_block *tm;
 937         unsigned int row;
 938
 939         for (row = 0; row < max_rows; row++, hb++) {
 940                 spin_lock_bh(&tcp_metrics_lock);
 941                 tm = deref_locked_genl(hb->chain);
 942                 if (tm)
 943                         hb->chain = NULL;
 944                 spin_unlock_bh(&tcp_metrics_lock);
 945                 while (tm) {
 946                         struct tcp_metrics_block *next;
 947
 948                         next = deref_genl(tm->tcpm_next);
 949                         kfree_rcu(tm, rcu_head);
 950                         tm = next;
 951                 }
 952         }
 953         return 0;
 954 }
 955
 956 static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info)
 957 {
 958         struct tcpm_hash_bucket *hb;
 959         struct tcp_metrics_block *tm;
 960         struct tcp_metrics_block __rcu **pp;
 961         struct inetpeer_addr addr;
 962         unsigned int hash;
 963         struct net *net = genl_info_net(info);
 964         int ret;
 965
 966         ret = parse_nl_addr(info, &addr, &hash, 1);
 967         if (ret < 0)
 968                 return ret;
 969         if (ret > 0)
 970                 return tcp_metrics_flush_all(net);
 971
 972         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 973         hb = net->ipv4.tcp_metrics_hash + hash;
 974         pp = &hb->chain;
 975         spin_lock_bh(&tcp_metrics_lock);
 976         for (tm = deref_locked_genl(*pp); tm;
 977              pp = &tm->tcpm_next, tm = deref_locked_genl(*pp)) {
 978                 if (addr_same(&tm->tcpm_addr, &addr)) {
 979                         *pp = tm->tcpm_next;
 980                         break;
 981                 }
 982         }
 983         spin_unlock_bh(&tcp_metrics_lock);
 984         if (!tm)
 985                 return -ESRCH;
 986         kfree_rcu(tm, rcu_head);
 987         return 0;
 988 }
 989
 990 static struct genl_ops tcp_metrics_nl_ops[] = {
 991         {
 992                 .cmd = TCP_METRICS_CMD_GET,
 993                 .doit = tcp_metrics_nl_cmd_get,
 994                 .dumpit = tcp_metrics_nl_dump,
 995                 .policy = tcp_metrics_nl_policy,
 996                 .flags = GENL_ADMIN_PERM,
 997         },
 998         {
 999                 .cmd = TCP_METRICS_CMD_DEL,
1000                 .doit = tcp_metrics_nl_cmd_del,
1001                 .policy = tcp_metrics_nl_policy,
1002                 .flags = GENL_ADMIN_PERM,
1003         },
1004 };
1005
1006 static unsigned int tcpmhash_entries;
1007 static int __init set_tcpmhash_entries(char *str)
1008 {
1009         ssize_t ret;
1010
1011         if (!str)
1012                 return 0;
1013
1014         ret = kstrtouint(str, 0, &tcpmhash_entries);
1015         if (ret)
1016                 return 0;
1017
1018         return 1;
1019 }
1020 __setup("tcpmhash_entries=", set_tcpmhash_entries);
1021
1022 static int __net_init tcp_net_metrics_init(struct net *net)
1023 {
1024         size_t size;
1025         unsigned int slots;
1026
1027         slots = tcpmhash_entries;
1028         if (!slots) {
1029                 if (totalram_pages >= 128 * 1024)
1030                         slots = 16 * 1024;
1031                 else
1032                         slots = 8 * 1024;
1033         }
1034
1035         net->ipv4.tcp_metrics_hash_log = order_base_2(slots);
1036         size = sizeof(struct tcpm_hash_bucket) << net->ipv4.tcp_metrics_hash_log;
1037
1038         net->ipv4.tcp_metrics_hash = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
1039         if (!net->ipv4.tcp_metrics_hash)
1040                 net->ipv4.tcp_metrics_hash = vzalloc(size);
1041
1042         if (!net->ipv4.tcp_metrics_hash)
1043                 return -ENOMEM;
1044
1045         return 0;
1046 }
1047
1048 static void __net_exit tcp_net_metrics_exit(struct net *net)
1049 {
1050         unsigned int i;
1051
1052         for (i = 0; i < (1U << net->ipv4.tcp_metrics_hash_log) ; i++) {
1053                 struct tcp_metrics_block *tm, *next;
1054
1055                 tm = rcu_dereference_protected(net->ipv4.tcp_metrics_hash[i].chain, 1);
1056                 while (tm) {
1057                         next = rcu_dereference_protected(tm->tcpm_next, 1);
1058                         kfree(tm);
1059                         tm = next;
1060                 }
1061         }
1062         if (is_vmalloc_addr(net->ipv4.tcp_metrics_hash))
1063                 vfree(net->ipv4.tcp_metrics_hash);
1064         else
1065                 kfree(net->ipv4.tcp_metrics_hash);
1066 }
1067
1068 static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
1069         .init   =       tcp_net_metrics_init,
1070         .exit   =       tcp_net_metrics_exit,
1071 };
1072
1073 void __init tcp_metrics_init(void)
1074 {
1075         int ret;
1076
1077         ret = register_pernet_subsys(&tcp_net_metrics_ops);
1078         if (ret < 0)
1079                 goto cleanup;
1080         ret = genl_register_family_with_ops(&tcp_metrics_nl_family,
1081                                             tcp_metrics_nl_ops,
1082                                             ARRAY_SIZE(tcp_metrics_nl_ops));
1083         if (ret < 0)
1084                 goto cleanup_subsys;
1085         return;
1086
1087 cleanup_subsys:
1088         unregister_pernet_subsys(&tcp_net_metrics_ops);
1089
1090 cleanup:
1091         return;
1092 }