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 #include <linux/tcp_metrics.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 {
 101         u32 val;
 102
 103         tm->tcpm_stamp = jiffies;
 104
 105         val = 0;
 106         if (dst_metric_locked(dst, RTAX_RTT))
 107                 val |= 1 << TCP_METRIC_RTT;
 108         if (dst_metric_locked(dst, RTAX_RTTVAR))
 109                 val |= 1 << TCP_METRIC_RTTVAR;
 110         if (dst_metric_locked(dst, RTAX_SSTHRESH))
 111                 val |= 1 << TCP_METRIC_SSTHRESH;
 112         if (dst_metric_locked(dst, RTAX_CWND))
 113                 val |= 1 << TCP_METRIC_CWND;
 114         if (dst_metric_locked(dst, RTAX_REORDERING))
 115                 val |= 1 << TCP_METRIC_REORDERING;
 116         tm->tcpm_lock = val;
 117
 118         tm->tcpm_vals[TCP_METRIC_RTT] = dst_metric_raw(dst, RTAX_RTT);
 119         tm->tcpm_vals[TCP_METRIC_RTTVAR] = dst_metric_raw(dst, RTAX_RTTVAR);
 120         tm->tcpm_vals[TCP_METRIC_SSTHRESH] = dst_metric_raw(dst, RTAX_SSTHRESH);
 121         tm->tcpm_vals[TCP_METRIC_CWND] = dst_metric_raw(dst, RTAX_CWND);
 122         tm->tcpm_vals[TCP_METRIC_REORDERING] = dst_metric_raw(dst, RTAX_REORDERING);
 123         tm->tcpm_ts = 0;
 124         tm->tcpm_ts_stamp = 0;
 125         tm->tcpm_fastopen.mss = 0;
 126         tm->tcpm_fastopen.syn_loss = 0;
 127         tm->tcpm_fastopen.cookie.len = 0;
 128 }
 129
 130 static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
 131                                           struct inetpeer_addr *addr,
 132                                           unsigned int hash,
 133                                           bool reclaim)
 134 {
 135         struct tcp_metrics_block *tm;
 136         struct net *net;
 137
 138         spin_lock_bh(&tcp_metrics_lock);
 139         net = dev_net(dst->dev);
 140         if (unlikely(reclaim)) {
 141                 struct tcp_metrics_block *oldest;
 142
 143                 oldest = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain);
 144                 for (tm = rcu_dereference(oldest->tcpm_next); tm;
 145                      tm = rcu_dereference(tm->tcpm_next)) {
 146                         if (time_before(tm->tcpm_stamp, oldest->tcpm_stamp))
 147                                 oldest = tm;
 148                 }
 149                 tm = oldest;
 150         } else {
 151                 tm = kmalloc(sizeof(*tm), GFP_ATOMIC);
 152                 if (!tm)
 153                         goto out_unlock;
 154         }
 155         tm->tcpm_addr = *addr;
 156
 157         tcpm_suck_dst(tm, dst);
 158
 159         if (likely(!reclaim)) {
 160                 tm->tcpm_next = net->ipv4.tcp_metrics_hash[hash].chain;
 161                 rcu_assign_pointer(net->ipv4.tcp_metrics_hash[hash].chain, tm);
 162         }
 163
 164 out_unlock:
 165         spin_unlock_bh(&tcp_metrics_lock);
 166         return tm;
 167 }
 168
 169 #define TCP_METRICS_TIMEOUT             (60 * 60 * HZ)
 170
 171 static void tcpm_check_stamp(struct tcp_metrics_block *tm, struct dst_entry *dst)
 172 {
 173         if (tm && unlikely(time_after(jiffies, tm->tcpm_stamp + TCP_METRICS_TIMEOUT)))
 174                 tcpm_suck_dst(tm, dst);
 175 }
 176
 177 #define TCP_METRICS_RECLAIM_DEPTH       5
 178 #define TCP_METRICS_RECLAIM_PTR         (struct tcp_metrics_block *) 0x1UL
 179
 180 static struct tcp_metrics_block *tcp_get_encode(struct tcp_metrics_block *tm, int depth)
 181 {
 182         if (tm)
 183                 return tm;
 184         if (depth > TCP_METRICS_RECLAIM_DEPTH)
 185                 return TCP_METRICS_RECLAIM_PTR;
 186         return NULL;
 187 }
 188
 189 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *addr,
 190                                                    struct net *net, unsigned int hash)
 191 {
 192         struct tcp_metrics_block *tm;
 193         int depth = 0;
 194
 195         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 196              tm = rcu_dereference(tm->tcpm_next)) {
 197                 if (addr_same(&tm->tcpm_addr, addr))
 198                         break;
 199                 depth++;
 200         }
 201         return tcp_get_encode(tm, depth);
 202 }
 203
 204 static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
 205                                                        struct dst_entry *dst)
 206 {
 207         struct tcp_metrics_block *tm;
 208         struct inetpeer_addr addr;
 209         unsigned int hash;
 210         struct net *net;
 211
 212         addr.family = req->rsk_ops->family;
 213         switch (addr.family) {
 214         case AF_INET:
 215                 addr.addr.a4 = inet_rsk(req)->rmt_addr;
 216                 hash = (__force unsigned int) addr.addr.a4;
 217                 break;
 218         case AF_INET6:
 219                 *(struct in6_addr *)addr.addr.a6 = inet6_rsk(req)->rmt_addr;
 220                 hash = ipv6_addr_hash(&inet6_rsk(req)->rmt_addr);
 221                 break;
 222         default:
 223                 return NULL;
 224         }
 225
 226         net = dev_net(dst->dev);
 227         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 228
 229         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 230              tm = rcu_dereference(tm->tcpm_next)) {
 231                 if (addr_same(&tm->tcpm_addr, &addr))
 232                         break;
 233         }
 234         tcpm_check_stamp(tm, dst);
 235         return tm;
 236 }
 237
 238 static struct tcp_metrics_block *__tcp_get_metrics_tw(struct inet_timewait_sock *tw)
 239 {
 240         struct inet6_timewait_sock *tw6;
 241         struct tcp_metrics_block *tm;
 242         struct inetpeer_addr addr;
 243         unsigned int hash;
 244         struct net *net;
 245
 246         addr.family = tw->tw_family;
 247         switch (addr.family) {
 248         case AF_INET:
 249                 addr.addr.a4 = tw->tw_daddr;
 250                 hash = (__force unsigned int) addr.addr.a4;
 251                 break;
 252         case AF_INET6:
 253                 tw6 = inet6_twsk((struct sock *)tw);
 254                 *(struct in6_addr *)addr.addr.a6 = tw6->tw_v6_daddr;
 255                 hash = ipv6_addr_hash(&tw6->tw_v6_daddr);
 256                 break;
 257         default:
 258                 return NULL;
 259         }
 260
 261         net = twsk_net(tw);
 262         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 263
 264         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 265              tm = rcu_dereference(tm->tcpm_next)) {
 266                 if (addr_same(&tm->tcpm_addr, &addr))
 267                         break;
 268         }
 269         return tm;
 270 }
 271
 272 static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
 273                                                  struct dst_entry *dst,
 274                                                  bool create)
 275 {
 276         struct tcp_metrics_block *tm;
 277         struct inetpeer_addr addr;
 278         unsigned int hash;
 279         struct net *net;
 280         bool reclaim;
 281
 282         addr.family = sk->sk_family;
 283         switch (addr.family) {
 284         case AF_INET:
 285                 addr.addr.a4 = inet_sk(sk)->inet_daddr;
 286                 hash = (__force unsigned int) addr.addr.a4;
 287                 break;
 288         case AF_INET6:
 289                 *(struct in6_addr *)addr.addr.a6 = inet6_sk(sk)->daddr;
 290                 hash = ipv6_addr_hash(&inet6_sk(sk)->daddr);
 291                 break;
 292         default:
 293                 return NULL;
 294         }
 295
 296         net = dev_net(dst->dev);
 297         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 298
 299         tm = __tcp_get_metrics(&addr, net, hash);
 300         reclaim = false;
 301         if (tm == TCP_METRICS_RECLAIM_PTR) {
 302                 reclaim = true;
 303                 tm = NULL;
 304         }
 305         if (!tm && create)
 306                 tm = tcpm_new(dst, &addr, hash, reclaim);
 307         else
 308                 tcpm_check_stamp(tm, dst);
 309
 310         return tm;
 311 }
 312
 313 /* Save metrics learned by this TCP session.  This function is called
 314  * only, when TCP finishes successfully i.e. when it enters TIME-WAIT
 315  * or goes from LAST-ACK to CLOSE.
 316  */
 317 void tcp_update_metrics(struct sock *sk)
 318 {
 319         const struct inet_connection_sock *icsk = inet_csk(sk);
 320         struct dst_entry *dst = __sk_dst_get(sk);
 321         struct tcp_sock *tp = tcp_sk(sk);
 322         struct tcp_metrics_block *tm;
 323         unsigned long rtt;
 324         u32 val;
 325         int m;
 326
 327         if (sysctl_tcp_nometrics_save || !dst)
 328                 return;
 329
 330         if (dst->flags & DST_HOST)
 331                 dst_confirm(dst);
 332
 333         rcu_read_lock();
 334         if (icsk->icsk_backoff || !tp->srtt) {
 335                 /* This session failed to estimate rtt. Why?
 336                  * Probably, no packets returned in time.  Reset our
 337                  * results.
 338                  */
 339                 tm = tcp_get_metrics(sk, dst, false);
 340                 if (tm && !tcp_metric_locked(tm, TCP_METRIC_RTT))
 341                         tcp_metric_set(tm, TCP_METRIC_RTT, 0);
 342                 goto out_unlock;
 343         } else
 344                 tm = tcp_get_metrics(sk, dst, true);
 345
 346         if (!tm)
 347                 goto out_unlock;
 348
 349         rtt = tcp_metric_get_jiffies(tm, TCP_METRIC_RTT);
 350         m = rtt - tp->srtt;
 351
 352         /* If newly calculated rtt larger than stored one, store new
 353          * one. Otherwise, use EWMA. Remember, rtt overestimation is
 354          * always better than underestimation.
 355          */
 356         if (!tcp_metric_locked(tm, TCP_METRIC_RTT)) {
 357                 if (m <= 0)
 358                         rtt = tp->srtt;
 359                 else
 360                         rtt -= (m >> 3);
 361                 tcp_metric_set_msecs(tm, TCP_METRIC_RTT, rtt);
 362         }
 363
 364         if (!tcp_metric_locked(tm, TCP_METRIC_RTTVAR)) {
 365                 unsigned long var;
 366
 367                 if (m < 0)
 368                         m = -m;
 369
 370                 /* Scale deviation to rttvar fixed point */
 371                 m >>= 1;
 372                 if (m < tp->mdev)
 373                         m = tp->mdev;
 374
 375                 var = tcp_metric_get_jiffies(tm, TCP_METRIC_RTTVAR);
 376                 if (m >= var)
 377                         var = m;
 378                 else
 379                         var -= (var - m) >> 2;
 380
 381                 tcp_metric_set_msecs(tm, TCP_METRIC_RTTVAR, var);
 382         }
 383
 384         if (tcp_in_initial_slowstart(tp)) {
 385                 /* Slow start still did not finish. */
 386                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 387                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 388                         if (val && (tp->snd_cwnd >> 1) > val)
 389                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 390                                                tp->snd_cwnd >> 1);
 391                 }
 392                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 393                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 394                         if (tp->snd_cwnd > val)
 395                                 tcp_metric_set(tm, TCP_METRIC_CWND,
 396                                                tp->snd_cwnd);
 397                 }
 398         } else if (tp->snd_cwnd > tp->snd_ssthresh &&
 399                    icsk->icsk_ca_state == TCP_CA_Open) {
 400                 /* Cong. avoidance phase, cwnd is reliable. */
 401                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
 402                         tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 403                                        max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
 404                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 405                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 406                         tcp_metric_set(tm, TCP_METRIC_CWND, (val + tp->snd_cwnd) >> 1);
 407                 }
 408         } else {
 409                 /* Else slow start did not finish, cwnd is non-sense,
 410                  * ssthresh may be also invalid.
 411                  */
 412                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 413                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 414                         tcp_metric_set(tm, TCP_METRIC_CWND,
 415                                        (val + tp->snd_ssthresh) >> 1);
 416                 }
 417                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 418                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 419                         if (val && tp->snd_ssthresh > val)
 420                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 421                                                tp->snd_ssthresh);
 422                 }
 423                 if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {
 424                         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 425                         if (val < tp->reordering &&
 426                             tp->reordering != sysctl_tcp_reordering)
 427                                 tcp_metric_set(tm, TCP_METRIC_REORDERING,
 428                                                tp->reordering);
 429                 }
 430         }
 431         tm->tcpm_stamp = jiffies;
 432 out_unlock:
 433         rcu_read_unlock();
 434 }
 435
 436 /* Initialize metrics on socket. */
 437
 438 void tcp_init_metrics(struct sock *sk)
 439 {
 440         struct dst_entry *dst = __sk_dst_get(sk);
 441         struct tcp_sock *tp = tcp_sk(sk);
 442         struct tcp_metrics_block *tm;
 443         u32 val;
 444
 445         if (dst == NULL)
 446                 goto reset;
 447
 448         dst_confirm(dst);
 449
 450         rcu_read_lock();
 451         tm = tcp_get_metrics(sk, dst, true);
 452         if (!tm) {
 453                 rcu_read_unlock();
 454                 goto reset;
 455         }
 456
 457         if (tcp_metric_locked(tm, TCP_METRIC_CWND))
 458                 tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
 459
 460         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 461         if (val) {
 462                 tp->snd_ssthresh = val;
 463                 if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
 464                         tp->snd_ssthresh = tp->snd_cwnd_clamp;
 465         } else {
 466                 /* ssthresh may have been reduced unnecessarily during.
 467                  * 3WHS. Restore it back to its initial default.
 468                  */
 469                 tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
 470         }
 471         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 472         if (val && tp->reordering != val) {
 473                 tcp_disable_fack(tp);
 474                 tcp_disable_early_retrans(tp);
 475                 tp->reordering = val;
 476         }
 477
 478         val = tcp_metric_get(tm, TCP_METRIC_RTT);
 479         if (val == 0 || tp->srtt == 0) {
 480                 rcu_read_unlock();
 481                 goto reset;
 482         }
 483         /* Initial rtt is determined from SYN,SYN-ACK.
 484          * The segment is small and rtt may appear much
 485          * less than real one. Use per-dst memory
 486          * to make it more realistic.
 487          *
 488          * A bit of theory. RTT is time passed after "normal" sized packet
 489          * is sent until it is ACKed. In normal circumstances sending small
 490          * packets force peer to delay ACKs and calculation is correct too.
 491          * The algorithm is adaptive and, provided we follow specs, it
 492          * NEVER underestimate RTT. BUT! If peer tries to make some clever
 493          * tricks sort of "quick acks" for time long enough to decrease RTT
 494          * to low value, and then abruptly stops to do it and starts to delay
 495          * ACKs, wait for troubles.
 496          */
 497         val = msecs_to_jiffies(val);
 498         if (val > tp->srtt) {
 499                 tp->srtt = val;
 500                 tp->rtt_seq = tp->snd_nxt;
 501         }
 502         val = tcp_metric_get_jiffies(tm, TCP_METRIC_RTTVAR);
 503         if (val > tp->mdev) {
 504                 tp->mdev = val;
 505                 tp->mdev_max = tp->rttvar = max(tp->mdev, tcp_rto_min(sk));
 506         }
 507         rcu_read_unlock();
 508
 509         tcp_set_rto(sk);
 510 reset:
 511         if (tp->srtt == 0) {
 512                 /* RFC6298: 5.7 We've failed to get a valid RTT sample from
 513                  * 3WHS. This is most likely due to retransmission,
 514                  * including spurious one. Reset the RTO back to 3secs
 515                  * from the more aggressive 1sec to avoid more spurious
 516                  * retransmission.
 517                  */
 518                 tp->mdev = tp->mdev_max = tp->rttvar = TCP_TIMEOUT_FALLBACK;
 519                 inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
 520         }
 521         /* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
 522          * retransmitted. In light of RFC6298 more aggressive 1sec
 523          * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
 524          * retransmission has occurred.
 525          */
 526         if (tp->total_retrans > 1)
 527                 tp->snd_cwnd = 1;
 528         else
 529                 tp->snd_cwnd = tcp_init_cwnd(tp, dst);
 530         tp->snd_cwnd_stamp = tcp_time_stamp;
 531 }
 532
 533 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, bool paws_check)
 534 {
 535         struct tcp_metrics_block *tm;
 536         bool ret;
 537
 538         if (!dst)
 539                 return false;
 540
 541         rcu_read_lock();
 542         tm = __tcp_get_metrics_req(req, dst);
 543         if (paws_check) {
 544                 if (tm &&
 545                     (u32)get_seconds() - tm->tcpm_ts_stamp < TCP_PAWS_MSL &&
 546                     (s32)(tm->tcpm_ts - req->ts_recent) > TCP_PAWS_WINDOW)
 547                         ret = false;
 548                 else
 549                         ret = true;
 550         } else {
 551                 if (tm && tcp_metric_get(tm, TCP_METRIC_RTT) && tm->tcpm_ts_stamp)
 552                         ret = true;
 553                 else
 554                         ret = false;
 555         }
 556         rcu_read_unlock();
 557
 558         return ret;
 559 }
 560 EXPORT_SYMBOL_GPL(tcp_peer_is_proven);
 561
 562 void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst)
 563 {
 564         struct tcp_metrics_block *tm;
 565
 566         rcu_read_lock();
 567         tm = tcp_get_metrics(sk, dst, true);
 568         if (tm) {
 569                 struct tcp_sock *tp = tcp_sk(sk);
 570
 571                 if ((u32)get_seconds() - tm->tcpm_ts_stamp <= TCP_PAWS_MSL) {
 572                         tp->rx_opt.ts_recent_stamp = tm->tcpm_ts_stamp;
 573                         tp->rx_opt.ts_recent = tm->tcpm_ts;
 574                 }
 575         }
 576         rcu_read_unlock();
 577 }
 578 EXPORT_SYMBOL_GPL(tcp_fetch_timewait_stamp);
 579
 580 /* VJ's idea. Save last timestamp seen from this destination and hold
 581  * it at least for normal timewait interval to use for duplicate
 582  * segment detection in subsequent connections, before they enter
 583  * synchronized state.
 584  */
 585 bool tcp_remember_stamp(struct sock *sk)
 586 {
 587         struct dst_entry *dst = __sk_dst_get(sk);
 588         bool ret = false;
 589
 590         if (dst) {
 591                 struct tcp_metrics_block *tm;
 592
 593                 rcu_read_lock();
 594                 tm = tcp_get_metrics(sk, dst, true);
 595                 if (tm) {
 596                         struct tcp_sock *tp = tcp_sk(sk);
 597
 598                         if ((s32)(tm->tcpm_ts - tp->rx_opt.ts_recent) <= 0 ||
 599                             ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 600                              tm->tcpm_ts_stamp <= (u32)tp->rx_opt.ts_recent_stamp)) {
 601                                 tm->tcpm_ts_stamp = (u32)tp->rx_opt.ts_recent_stamp;
 602                                 tm->tcpm_ts = tp->rx_opt.ts_recent;
 603                         }
 604                         ret = true;
 605                 }
 606                 rcu_read_unlock();
 607         }
 608         return ret;
 609 }
 610
 611 bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw)
 612 {
 613         struct tcp_metrics_block *tm;
 614         bool ret = false;
 615
 616         rcu_read_lock();
 617         tm = __tcp_get_metrics_tw(tw);
 618         if (tm) {
 619                 const struct tcp_timewait_sock *tcptw;
 620                 struct sock *sk = (struct sock *) tw;
 621
 622                 tcptw = tcp_twsk(sk);
 623                 if ((s32)(tm->tcpm_ts - tcptw->tw_ts_recent) <= 0 ||
 624                     ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
 625                      tm->tcpm_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) {
 626                         tm->tcpm_ts_stamp = (u32)tcptw->tw_ts_recent_stamp;
 627                         tm->tcpm_ts        = tcptw->tw_ts_recent;
 628                 }
 629                 ret = true;
 630         }
 631         rcu_read_unlock();
 632
 633         return ret;
 634 }
 635
 636 static DEFINE_SEQLOCK(fastopen_seqlock);
 637
 638 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
 639                             struct tcp_fastopen_cookie *cookie,
 640                             int *syn_loss, unsigned long *last_syn_loss)
 641 {
 642         struct tcp_metrics_block *tm;
 643
 644         rcu_read_lock();
 645         tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
 646         if (tm) {
 647                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 648                 unsigned int seq;
 649
 650                 do {
 651                         seq = read_seqbegin(&fastopen_seqlock);
 652                         if (tfom->mss)
 653                                 *mss = tfom->mss;
 654                         *cookie = tfom->cookie;
 655                         *syn_loss = tfom->syn_loss;
 656                         *last_syn_loss = *syn_loss ? tfom->last_syn_loss : 0;
 657                 } while (read_seqretry(&fastopen_seqlock, seq));
 658         }
 659         rcu_read_unlock();
 660 }
 661
 662 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
 663                             struct tcp_fastopen_cookie *cookie, bool syn_lost)
 664 {
 665         struct tcp_metrics_block *tm;
 666
 667         rcu_read_lock();
 668         tm = tcp_get_metrics(sk, __sk_dst_get(sk), true);
 669         if (tm) {
 670                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 671
 672                 write_seqlock_bh(&fastopen_seqlock);
 673                 tfom->mss = mss;
 674                 if (cookie->len > 0)
 675                         tfom->cookie = *cookie;
 676                 if (syn_lost) {
 677                         ++tfom->syn_loss;
 678                         tfom->last_syn_loss = jiffies;
 679                 } else
 680                         tfom->syn_loss = 0;
 681                 write_sequnlock_bh(&fastopen_seqlock);
 682         }
 683         rcu_read_unlock();
 684 }
 685
 686 static struct genl_family tcp_metrics_nl_family = {
 687         .id             = GENL_ID_GENERATE,
 688         .hdrsize        = 0,
 689         .name           = TCP_METRICS_GENL_NAME,
 690         .version        = TCP_METRICS_GENL_VERSION,
 691         .maxattr        = TCP_METRICS_ATTR_MAX,
 692         .netnsok        = true,
 693 };
 694
 695 static struct nla_policy tcp_metrics_nl_policy[TCP_METRICS_ATTR_MAX + 1] = {
 696         [TCP_METRICS_ATTR_ADDR_IPV4]    = { .type = NLA_U32, },
 697         [TCP_METRICS_ATTR_ADDR_IPV6]    = { .type = NLA_BINARY,
 698                                             .len = sizeof(struct in6_addr), },
 699         /* Following attributes are not received for GET/DEL,
 700          * we keep them for reference
 701          */
 702 #if 0
 703         [TCP_METRICS_ATTR_AGE]          = { .type = NLA_MSECS, },
 704         [TCP_METRICS_ATTR_TW_TSVAL]     = { .type = NLA_U32, },
 705         [TCP_METRICS_ATTR_TW_TS_STAMP]  = { .type = NLA_S32, },
 706         [TCP_METRICS_ATTR_VALS]         = { .type = NLA_NESTED, },
 707         [TCP_METRICS_ATTR_FOPEN_MSS]    = { .type = NLA_U16, },
 708         [TCP_METRICS_ATTR_FOPEN_SYN_DROPS]      = { .type = NLA_U16, },
 709         [TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS]    = { .type = NLA_MSECS, },
 710         [TCP_METRICS_ATTR_FOPEN_COOKIE] = { .type = NLA_BINARY,
 711                                             .len = TCP_FASTOPEN_COOKIE_MAX, },
 712 #endif
 713 };
 714
 715 /* Add attributes, caller cancels its header on failure */
 716 static int tcp_metrics_fill_info(struct sk_buff *msg,
 717                                  struct tcp_metrics_block *tm)
 718 {
 719         struct nlattr *nest;
 720         int i;
 721
 722         switch (tm->tcpm_addr.family) {
 723         case AF_INET:
 724                 if (nla_put_be32(msg, TCP_METRICS_ATTR_ADDR_IPV4,
 725                                 tm->tcpm_addr.addr.a4) < 0)
 726                         goto nla_put_failure;
 727                 break;
 728         case AF_INET6:
 729                 if (nla_put(msg, TCP_METRICS_ATTR_ADDR_IPV6, 16,
 730                             tm->tcpm_addr.addr.a6) < 0)
 731                         goto nla_put_failure;
 732                 break;
 733         default:
 734                 return -EAFNOSUPPORT;
 735         }
 736
 737         if (nla_put_msecs(msg, TCP_METRICS_ATTR_AGE,
 738                           jiffies - tm->tcpm_stamp) < 0)
 739                 goto nla_put_failure;
 740         if (tm->tcpm_ts_stamp) {
 741                 if (nla_put_s32(msg, TCP_METRICS_ATTR_TW_TS_STAMP,
 742                                 (s32) (get_seconds() - tm->tcpm_ts_stamp)) < 0)
 743                         goto nla_put_failure;
 744                 if (nla_put_u32(msg, TCP_METRICS_ATTR_TW_TSVAL,
 745                                 tm->tcpm_ts) < 0)
 746                         goto nla_put_failure;
 747         }
 748
 749         {
 750                 int n = 0;
 751
 752                 nest = nla_nest_start(msg, TCP_METRICS_ATTR_VALS);
 753                 if (!nest)
 754                         goto nla_put_failure;
 755                 for (i = 0; i < TCP_METRIC_MAX + 1; i++) {
 756                         if (!tm->tcpm_vals[i])
 757                                 continue;
 758                         if (nla_put_u32(msg, i + 1, tm->tcpm_vals[i]) < 0)
 759                                 goto nla_put_failure;
 760                         n++;
 761                 }
 762                 if (n)
 763                         nla_nest_end(msg, nest);
 764                 else
 765                         nla_nest_cancel(msg, nest);
 766         }
 767
 768         {
 769                 struct tcp_fastopen_metrics tfom_copy[1], *tfom;
 770                 unsigned int seq;
 771
 772                 do {
 773                         seq = read_seqbegin(&fastopen_seqlock);
 774                         tfom_copy[0] = tm->tcpm_fastopen;
 775                 } while (read_seqretry(&fastopen_seqlock, seq));
 776
 777                 tfom = tfom_copy;
 778                 if (tfom->mss &&
 779                     nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_MSS,
 780                                 tfom->mss) < 0)
 781                         goto nla_put_failure;
 782                 if (tfom->syn_loss &&
 783                     (nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROPS,
 784                                 tfom->syn_loss) < 0 ||
 785                      nla_put_msecs(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS,
 786                                 jiffies - tfom->last_syn_loss) < 0))
 787                         goto nla_put_failure;
 788                 if (tfom->cookie.len > 0 &&
 789                     nla_put(msg, TCP_METRICS_ATTR_FOPEN_COOKIE,
 790                             tfom->cookie.len, tfom->cookie.val) < 0)
 791                         goto nla_put_failure;
 792         }
 793
 794         return 0;
 795
 796 nla_put_failure:
 797         return -EMSGSIZE;
 798 }
 799
 800 static int tcp_metrics_dump_info(struct sk_buff *skb,
 801                                  struct netlink_callback *cb,
 802                                  struct tcp_metrics_block *tm)
 803 {
 804         void *hdr;
 805
 806         hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
 807                           &tcp_metrics_nl_family, NLM_F_MULTI,
 808                           TCP_METRICS_CMD_GET);
 809         if (!hdr)
 810                 return -EMSGSIZE;
 811
 812         if (tcp_metrics_fill_info(skb, tm) < 0)
 813                 goto nla_put_failure;
 814
 815         return genlmsg_end(skb, hdr);
 816
 817 nla_put_failure:
 818         genlmsg_cancel(skb, hdr);
 819         return -EMSGSIZE;
 820 }
 821
 822 static int tcp_metrics_nl_dump(struct sk_buff *skb,
 823                                struct netlink_callback *cb)
 824 {
 825         struct net *net = sock_net(skb->sk);
 826         unsigned int max_rows = 1U << net->ipv4.tcp_metrics_hash_log;
 827         unsigned int row, s_row = cb->args[0];
 828         int s_col = cb->args[1], col = s_col;
 829
 830         for (row = s_row; row < max_rows; row++, s_col = 0) {
 831                 struct tcp_metrics_block *tm;
 832                 struct tcpm_hash_bucket *hb = net->ipv4.tcp_metrics_hash + row;
 833
 834                 rcu_read_lock();
 835                 for (col = 0, tm = rcu_dereference(hb->chain); tm;
 836                      tm = rcu_dereference(tm->tcpm_next), col++) {
 837                         if (col < s_col)
 838                                 continue;
 839                         if (tcp_metrics_dump_info(skb, cb, tm) < 0) {
 840                                 rcu_read_unlock();
 841                                 goto done;
 842                         }
 843                 }
 844                 rcu_read_unlock();
 845         }
 846
 847 done:
 848         cb->args[0] = row;
 849         cb->args[1] = col;
 850         return skb->len;
 851 }
 852
 853 static int parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 854                          unsigned int *hash, int optional)
 855 {
 856         struct nlattr *a;
 857
 858         a = info->attrs[TCP_METRICS_ATTR_ADDR_IPV4];
 859         if (a) {
 860                 addr->family = AF_INET;
 861                 addr->addr.a4 = nla_get_be32(a);
 862                 *hash = (__force unsigned int) addr->addr.a4;
 863                 return 0;
 864         }
 865         a = info->attrs[TCP_METRICS_ATTR_ADDR_IPV6];
 866         if (a) {
 867                 if (nla_len(a) != sizeof(sizeof(struct in6_addr)))
 868                         return -EINVAL;
 869                 addr->family = AF_INET6;
 870                 memcpy(addr->addr.a6, nla_data(a), sizeof(addr->addr.a6));
 871                 *hash = ipv6_addr_hash((struct in6_addr *) addr->addr.a6);
 872                 return 0;
 873         }
 874         return optional ? 1 : -EAFNOSUPPORT;
 875 }
 876
 877 static int tcp_metrics_nl_cmd_get(struct sk_buff *skb, struct genl_info *info)
 878 {
 879         struct tcp_metrics_block *tm;
 880         struct inetpeer_addr addr;
 881         unsigned int hash;
 882         struct sk_buff *msg;
 883         struct net *net = genl_info_net(info);
 884         void *reply;
 885         int ret;
 886
 887         ret = parse_nl_addr(info, &addr, &hash, 0);
 888         if (ret < 0)
 889                 return ret;
 890
 891         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 892         if (!msg)
 893                 return -ENOMEM;
 894
 895         reply = genlmsg_put_reply(msg, info, &tcp_metrics_nl_family, 0,
 896                                   info->genlhdr->cmd);
 897         if (!reply)
 898                 goto nla_put_failure;
 899
 900         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 901         ret = -ESRCH;
 902         rcu_read_lock();
 903         for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
 904              tm = rcu_dereference(tm->tcpm_next)) {
 905                 if (addr_same(&tm->tcpm_addr, &addr)) {
 906                         ret = tcp_metrics_fill_info(msg, tm);
 907                         break;
 908                 }
 909         }
 910         rcu_read_unlock();
 911         if (ret < 0)
 912                 goto out_free;
 913
 914         genlmsg_end(msg, reply);
 915         return genlmsg_reply(msg, info);
 916
 917 nla_put_failure:
 918         ret = -EMSGSIZE;
 919
 920 out_free:
 921         nlmsg_free(msg);
 922         return ret;
 923 }
 924
 925 #define deref_locked_genl(p)    \
 926         rcu_dereference_protected(p, lockdep_genl_is_held() && \
 927                                      lockdep_is_held(&tcp_metrics_lock))
 928
 929 #define deref_genl(p)   rcu_dereference_protected(p, lockdep_genl_is_held())
 930
 931 static int tcp_metrics_flush_all(struct net *net)
 932 {
 933         unsigned int max_rows = 1U << net->ipv4.tcp_metrics_hash_log;
 934         struct tcpm_hash_bucket *hb = net->ipv4.tcp_metrics_hash;
 935         struct tcp_metrics_block *tm;
 936         unsigned int row;
 937
 938         for (row = 0; row < max_rows; row++, hb++) {
 939                 spin_lock_bh(&tcp_metrics_lock);
 940                 tm = deref_locked_genl(hb->chain);
 941                 if (tm)
 942                         hb->chain = NULL;
 943                 spin_unlock_bh(&tcp_metrics_lock);
 944                 while (tm) {
 945                         struct tcp_metrics_block *next;
 946
 947                         next = deref_genl(tm->tcpm_next);
 948                         kfree_rcu(tm, rcu_head);
 949                         tm = next;
 950                 }
 951         }
 952         return 0;
 953 }
 954
 955 static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info)
 956 {
 957         struct tcpm_hash_bucket *hb;
 958         struct tcp_metrics_block *tm;
 959         struct tcp_metrics_block __rcu **pp;
 960         struct inetpeer_addr addr;
 961         unsigned int hash;
 962         struct net *net = genl_info_net(info);
 963         int ret;
 964
 965         ret = parse_nl_addr(info, &addr, &hash, 1);
 966         if (ret < 0)
 967                 return ret;
 968         if (ret > 0)
 969                 return tcp_metrics_flush_all(net);
 970
 971         hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
 972         hb = net->ipv4.tcp_metrics_hash + hash;
 973         pp = &hb->chain;
 974         spin_lock_bh(&tcp_metrics_lock);
 975         for (tm = deref_locked_genl(*pp); tm;
 976              pp = &tm->tcpm_next, tm = deref_locked_genl(*pp)) {
 977                 if (addr_same(&tm->tcpm_addr, &addr)) {
 978                         *pp = tm->tcpm_next;
 979                         break;
 980                 }
 981         }
 982         spin_unlock_bh(&tcp_metrics_lock);
 983         if (!tm)
 984                 return -ESRCH;
 985         kfree_rcu(tm, rcu_head);
 986         return 0;
 987 }
 988
 989 static struct genl_ops tcp_metrics_nl_ops[] = {
 990         {
 991                 .cmd = TCP_METRICS_CMD_GET,
 992                 .doit = tcp_metrics_nl_cmd_get,
 993                 .dumpit = tcp_metrics_nl_dump,
 994                 .policy = tcp_metrics_nl_policy,
 995                 .flags = GENL_ADMIN_PERM,
 996         },
 997         {
 998                 .cmd = TCP_METRICS_CMD_DEL,
 999                 .doit = tcp_metrics_nl_cmd_del,
1000                 .policy = tcp_metrics_nl_policy,
1001                 .flags = GENL_ADMIN_PERM,
1002         },
1003 };
1004
1005 static unsigned int tcpmhash_entries;
1006 static int __init set_tcpmhash_entries(char *str)
1007 {
1008         ssize_t ret;
1009
1010         if (!str)
1011                 return 0;
1012
1013         ret = kstrtouint(str, 0, &tcpmhash_entries);
1014         if (ret)
1015                 return 0;
1016
1017         return 1;
1018 }
1019 __setup("tcpmhash_entries=", set_tcpmhash_entries);
1020
1021 static int __net_init tcp_net_metrics_init(struct net *net)
1022 {
1023         size_t size;
1024         unsigned int slots;
1025
1026         slots = tcpmhash_entries;
1027         if (!slots) {
1028                 if (totalram_pages >= 128 * 1024)
1029                         slots = 16 * 1024;
1030                 else
1031                         slots = 8 * 1024;
1032         }
1033
1034         net->ipv4.tcp_metrics_hash_log = order_base_2(slots);
1035         size = sizeof(struct tcpm_hash_bucket) << net->ipv4.tcp_metrics_hash_log;
1036
1037         net->ipv4.tcp_metrics_hash = kzalloc(size, GFP_KERNEL);
1038         if (!net->ipv4.tcp_metrics_hash)
1039                 return -ENOMEM;
1040
1041         return 0;
1042 }
1043
1044 static void __net_exit tcp_net_metrics_exit(struct net *net)
1045 {
1046         unsigned int i;
1047
1048         for (i = 0; i < (1U << net->ipv4.tcp_metrics_hash_log) ; i++) {
1049                 struct tcp_metrics_block *tm, *next;
1050
1051                 tm = rcu_dereference_protected(net->ipv4.tcp_metrics_hash[i].chain, 1);
1052                 while (tm) {
1053                         next = rcu_dereference_protected(tm->tcpm_next, 1);
1054                         kfree(tm);
1055                         tm = next;
1056                 }
1057         }
1058         kfree(net->ipv4.tcp_metrics_hash);
1059 }
1060
1061 static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
1062         .init   =       tcp_net_metrics_init,
1063         .exit   =       tcp_net_metrics_exit,
1064 };
1065
1066 void __init tcp_metrics_init(void)
1067 {
1068         int ret;
1069
1070         ret = register_pernet_subsys(&tcp_net_metrics_ops);
1071         if (ret < 0)
1072                 goto cleanup;
1073         ret = genl_register_family_with_ops(&tcp_metrics_nl_family,
1074                                             tcp_metrics_nl_ops,
1075                                             ARRAY_SIZE(tcp_metrics_nl_ops));
1076         if (ret < 0)
1077                 goto cleanup_subsys;
1078         return;
1079
1080 cleanup_subsys:
1081         unregister_pernet_subsys(&tcp_net_metrics_ops);
1082
1083 cleanup:
1084         return;
1085 }