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 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
  26                                                    const struct inetpeer_addr *daddr,
  27                                                    struct net *net, unsigned int hash);
  28
  29 struct tcp_fastopen_metrics {
  30         u16     mss;
  31         u16     syn_loss:10,            /* Recurring Fast Open SYN losses */
  32                 try_exp:2;              /* Request w/ exp. option (once) */
  33         unsigned long   last_syn_loss;  /* Last Fast Open SYN loss */
  34         struct  tcp_fastopen_cookie     cookie;
  35 };
  36
  37 /* TCP_METRIC_MAX includes 2 extra fields for userspace compatibility
  38  * Kernel only stores RTT and RTTVAR in usec resolution
  39  */
  40 #define TCP_METRIC_MAX_KERNEL (TCP_METRIC_MAX - 2)
  41
  42 struct tcp_metrics_block {
  43         struct tcp_metrics_block __rcu  *tcpm_next;
  44         possible_net_t                  tcpm_net;
  45         struct inetpeer_addr            tcpm_saddr;
  46         struct inetpeer_addr            tcpm_daddr;
  47         unsigned long                   tcpm_stamp;
  48         u32                             tcpm_lock;
  49         u32                             tcpm_vals[TCP_METRIC_MAX_KERNEL + 1];
  50         struct tcp_fastopen_metrics     tcpm_fastopen;
  51
  52         struct rcu_head                 rcu_head;
  53 };
  54
  55 static inline struct net *tm_net(struct tcp_metrics_block *tm)
  56 {
  57         return read_pnet(&tm->tcpm_net);
  58 }
  59
  60 static bool tcp_metric_locked(struct tcp_metrics_block *tm,
  61                               enum tcp_metric_index idx)
  62 {
  63         return tm->tcpm_lock & (1 << idx);
  64 }
  65
  66 static u32 tcp_metric_get(struct tcp_metrics_block *tm,
  67                           enum tcp_metric_index idx)
  68 {
  69         return tm->tcpm_vals[idx];
  70 }
  71
  72 static void tcp_metric_set(struct tcp_metrics_block *tm,
  73                            enum tcp_metric_index idx,
  74                            u32 val)
  75 {
  76         tm->tcpm_vals[idx] = val;
  77 }
  78
  79 static bool addr_same(const struct inetpeer_addr *a,
  80                       const struct inetpeer_addr *b)
  81 {
  82         return inetpeer_addr_cmp(a, b) == 0;
  83 }
  84
  85 struct tcpm_hash_bucket {
  86         struct tcp_metrics_block __rcu  *chain;
  87 };
  88
  89 static struct tcpm_hash_bucket  *tcp_metrics_hash __read_mostly;
  90 static unsigned int             tcp_metrics_hash_log __read_mostly;
  91
  92 static DEFINE_SPINLOCK(tcp_metrics_lock);
  93
  94 static void tcpm_suck_dst(struct tcp_metrics_block *tm,
  95                           const struct dst_entry *dst,
  96                           bool fastopen_clear)
  97 {
  98         u32 msval;
  99         u32 val;
 100
 101         tm->tcpm_stamp = jiffies;
 102
 103         val = 0;
 104         if (dst_metric_locked(dst, RTAX_RTT))
 105                 val |= 1 << TCP_METRIC_RTT;
 106         if (dst_metric_locked(dst, RTAX_RTTVAR))
 107                 val |= 1 << TCP_METRIC_RTTVAR;
 108         if (dst_metric_locked(dst, RTAX_SSTHRESH))
 109                 val |= 1 << TCP_METRIC_SSTHRESH;
 110         if (dst_metric_locked(dst, RTAX_CWND))
 111                 val |= 1 << TCP_METRIC_CWND;
 112         if (dst_metric_locked(dst, RTAX_REORDERING))
 113                 val |= 1 << TCP_METRIC_REORDERING;
 114         tm->tcpm_lock = val;
 115
 116         msval = dst_metric_raw(dst, RTAX_RTT);
 117         tm->tcpm_vals[TCP_METRIC_RTT] = msval * USEC_PER_MSEC;
 118
 119         msval = dst_metric_raw(dst, RTAX_RTTVAR);
 120         tm->tcpm_vals[TCP_METRIC_RTTVAR] = msval * USEC_PER_MSEC;
 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         if (fastopen_clear) {
 125                 tm->tcpm_fastopen.mss = 0;
 126                 tm->tcpm_fastopen.syn_loss = 0;
 127                 tm->tcpm_fastopen.try_exp = 0;
 128                 tm->tcpm_fastopen.cookie.exp = false;
 129                 tm->tcpm_fastopen.cookie.len = 0;
 130         }
 131 }
 132
 133 #define TCP_METRICS_TIMEOUT             (60 * 60 * HZ)
 134
 135 static void tcpm_check_stamp(struct tcp_metrics_block *tm, struct dst_entry *dst)
 136 {
 137         if (tm && unlikely(time_after(jiffies, tm->tcpm_stamp + TCP_METRICS_TIMEOUT)))
 138                 tcpm_suck_dst(tm, dst, false);
 139 }
 140
 141 #define TCP_METRICS_RECLAIM_DEPTH       5
 142 #define TCP_METRICS_RECLAIM_PTR         (struct tcp_metrics_block *) 0x1UL
 143
 144 #define deref_locked(p) \
 145         rcu_dereference_protected(p, lockdep_is_held(&tcp_metrics_lock))
 146
 147 static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
 148                                           struct inetpeer_addr *saddr,
 149                                           struct inetpeer_addr *daddr,
 150                                           unsigned int hash)
 151 {
 152         struct tcp_metrics_block *tm;
 153         struct net *net;
 154         bool reclaim = false;
 155
 156         spin_lock_bh(&tcp_metrics_lock);
 157         net = dev_net(dst->dev);
 158
 159         /* While waiting for the spin-lock the cache might have been populated
 160          * with this entry and so we have to check again.
 161          */
 162         tm = __tcp_get_metrics(saddr, daddr, net, hash);
 163         if (tm == TCP_METRICS_RECLAIM_PTR) {
 164                 reclaim = true;
 165                 tm = NULL;
 166         }
 167         if (tm) {
 168                 tcpm_check_stamp(tm, dst);
 169                 goto out_unlock;
 170         }
 171
 172         if (unlikely(reclaim)) {
 173                 struct tcp_metrics_block *oldest;
 174
 175                 oldest = deref_locked(tcp_metrics_hash[hash].chain);
 176                 for (tm = deref_locked(oldest->tcpm_next); tm;
 177                      tm = deref_locked(tm->tcpm_next)) {
 178                         if (time_before(tm->tcpm_stamp, oldest->tcpm_stamp))
 179                                 oldest = tm;
 180                 }
 181                 tm = oldest;
 182         } else {
 183                 tm = kmalloc(sizeof(*tm), GFP_ATOMIC);
 184                 if (!tm)
 185                         goto out_unlock;
 186         }
 187         write_pnet(&tm->tcpm_net, net);
 188         tm->tcpm_saddr = *saddr;
 189         tm->tcpm_daddr = *daddr;
 190
 191         tcpm_suck_dst(tm, dst, true);
 192
 193         if (likely(!reclaim)) {
 194                 tm->tcpm_next = tcp_metrics_hash[hash].chain;
 195                 rcu_assign_pointer(tcp_metrics_hash[hash].chain, tm);
 196         }
 197
 198 out_unlock:
 199         spin_unlock_bh(&tcp_metrics_lock);
 200         return tm;
 201 }
 202
 203 static struct tcp_metrics_block *tcp_get_encode(struct tcp_metrics_block *tm, int depth)
 204 {
 205         if (tm)
 206                 return tm;
 207         if (depth > TCP_METRICS_RECLAIM_DEPTH)
 208                 return TCP_METRICS_RECLAIM_PTR;
 209         return NULL;
 210 }
 211
 212 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
 213                                                    const struct inetpeer_addr *daddr,
 214                                                    struct net *net, unsigned int hash)
 215 {
 216         struct tcp_metrics_block *tm;
 217         int depth = 0;
 218
 219         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
 220              tm = rcu_dereference(tm->tcpm_next)) {
 221                 if (addr_same(&tm->tcpm_saddr, saddr) &&
 222                     addr_same(&tm->tcpm_daddr, daddr) &&
 223                     net_eq(tm_net(tm), net))
 224                         break;
 225                 depth++;
 226         }
 227         return tcp_get_encode(tm, depth);
 228 }
 229
 230 static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
 231                                                        struct dst_entry *dst)
 232 {
 233         struct tcp_metrics_block *tm;
 234         struct inetpeer_addr saddr, daddr;
 235         unsigned int hash;
 236         struct net *net;
 237
 238         saddr.family = req->rsk_ops->family;
 239         daddr.family = req->rsk_ops->family;
 240         switch (daddr.family) {
 241         case AF_INET:
 242                 inetpeer_set_addr_v4(&saddr, inet_rsk(req)->ir_loc_addr);
 243                 inetpeer_set_addr_v4(&daddr, inet_rsk(req)->ir_rmt_addr);
 244                 hash = ipv4_addr_hash(inet_rsk(req)->ir_rmt_addr);
 245                 break;
 246 #if IS_ENABLED(CONFIG_IPV6)
 247         case AF_INET6:
 248                 inetpeer_set_addr_v6(&saddr, &inet_rsk(req)->ir_v6_loc_addr);
 249                 inetpeer_set_addr_v6(&daddr, &inet_rsk(req)->ir_v6_rmt_addr);
 250                 hash = ipv6_addr_hash(&inet_rsk(req)->ir_v6_rmt_addr);
 251                 break;
 252 #endif
 253         default:
 254                 return NULL;
 255         }
 256
 257         net = dev_net(dst->dev);
 258         hash ^= net_hash_mix(net);
 259         hash = hash_32(hash, tcp_metrics_hash_log);
 260
 261         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
 262              tm = rcu_dereference(tm->tcpm_next)) {
 263                 if (addr_same(&tm->tcpm_saddr, &saddr) &&
 264                     addr_same(&tm->tcpm_daddr, &daddr) &&
 265                     net_eq(tm_net(tm), net))
 266                         break;
 267         }
 268         tcpm_check_stamp(tm, dst);
 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 saddr, daddr;
 278         unsigned int hash;
 279         struct net *net;
 280
 281         if (sk->sk_family == AF_INET) {
 282                 inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
 283                 inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
 284                 hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
 285         }
 286 #if IS_ENABLED(CONFIG_IPV6)
 287         else if (sk->sk_family == AF_INET6) {
 288                 if (ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
 289                         inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
 290                         inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
 291                         hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
 292                 } else {
 293                         inetpeer_set_addr_v6(&saddr, &sk->sk_v6_rcv_saddr);
 294                         inetpeer_set_addr_v6(&daddr, &sk->sk_v6_daddr);
 295                         hash = ipv6_addr_hash(&sk->sk_v6_daddr);
 296                 }
 297         }
 298 #endif
 299         else
 300                 return NULL;
 301
 302         net = dev_net(dst->dev);
 303         hash ^= net_hash_mix(net);
 304         hash = hash_32(hash, tcp_metrics_hash_log);
 305
 306         tm = __tcp_get_metrics(&saddr, &daddr, net, hash);
 307         if (tm == TCP_METRICS_RECLAIM_PTR)
 308                 tm = NULL;
 309         if (!tm && create)
 310                 tm = tcpm_new(dst, &saddr, &daddr, hash);
 311         else
 312                 tcpm_check_stamp(tm, dst);
 313
 314         return tm;
 315 }
 316
 317 /* Save metrics learned by this TCP session.  This function is called
 318  * only, when TCP finishes successfully i.e. when it enters TIME-WAIT
 319  * or goes from LAST-ACK to CLOSE.
 320  */
 321 void tcp_update_metrics(struct sock *sk)
 322 {
 323         const struct inet_connection_sock *icsk = inet_csk(sk);
 324         struct dst_entry *dst = __sk_dst_get(sk);
 325         struct tcp_sock *tp = tcp_sk(sk);
 326         struct net *net = sock_net(sk);
 327         struct tcp_metrics_block *tm;
 328         unsigned long rtt;
 329         u32 val;
 330         int m;
 331
 332         sk_dst_confirm(sk);
 333         if (sysctl_tcp_nometrics_save || !dst)
 334                 return;
 335
 336         rcu_read_lock();
 337         if (icsk->icsk_backoff || !tp->srtt_us) {
 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(tm, TCP_METRIC_RTT);
 353         m = rtt - tp->srtt_us;
 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_us;
 362                 else
 363                         rtt -= (m >> 3);
 364                 tcp_metric_set(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_us)
 376                         m = tp->mdev_us;
 377
 378                 var = tcp_metric_get(tm, TCP_METRIC_RTTVAR);
 379                 if (m >= var)
 380                         var = m;
 381                 else
 382                         var -= (var - m) >> 2;
 383
 384                 tcp_metric_set(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 (!tcp_in_slow_start(tp) &&
 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 != net->ipv4.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, crtt = 0; /* cached RTT scaled by 8 */
 447
 448         sk_dst_confirm(sk);
 449         if (!dst)
 450                 goto reset;
 451
 452         rcu_read_lock();
 453         tm = tcp_get_metrics(sk, dst, true);
 454         if (!tm) {
 455                 rcu_read_unlock();
 456                 goto reset;
 457         }
 458
 459         if (tcp_metric_locked(tm, TCP_METRIC_CWND))
 460                 tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
 461
 462         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 463         if (val) {
 464                 tp->snd_ssthresh = val;
 465                 if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
 466                         tp->snd_ssthresh = tp->snd_cwnd_clamp;
 467         } else {
 468                 /* ssthresh may have been reduced unnecessarily during.
 469                  * 3WHS. Restore it back to its initial default.
 470                  */
 471                 tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
 472         }
 473         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 474         if (val && tp->reordering != val) {
 475                 tcp_disable_fack(tp);
 476                 tp->reordering = val;
 477         }
 478
 479         crtt = tcp_metric_get(tm, TCP_METRIC_RTT);
 480         rcu_read_unlock();
 481 reset:
 482         /* The initial RTT measurement from the SYN/SYN-ACK is not ideal
 483          * to seed the RTO for later data packets because SYN packets are
 484          * small. Use the per-dst cached values to seed the RTO but keep
 485          * the RTT estimator variables intact (e.g., srtt, mdev, rttvar).
 486          * Later the RTO will be updated immediately upon obtaining the first
 487          * data RTT sample (tcp_rtt_estimator()). Hence the cached RTT only
 488          * influences the first RTO but not later RTT estimation.
 489          *
 490          * But if RTT is not available from the SYN (due to retransmits or
 491          * syn cookies) or the cache, force a conservative 3secs timeout.
 492          *
 493          * A bit of theory. RTT is time passed after "normal" sized packet
 494          * is sent until it is ACKed. In normal circumstances sending small
 495          * packets force peer to delay ACKs and calculation is correct too.
 496          * The algorithm is adaptive and, provided we follow specs, it
 497          * NEVER underestimate RTT. BUT! If peer tries to make some clever
 498          * tricks sort of "quick acks" for time long enough to decrease RTT
 499          * to low value, and then abruptly stops to do it and starts to delay
 500          * ACKs, wait for troubles.
 501          */
 502         if (crtt > tp->srtt_us) {
 503                 /* Set RTO like tcp_rtt_estimator(), but from cached RTT. */
 504                 crtt /= 8 * USEC_PER_SEC / HZ;
 505                 inet_csk(sk)->icsk_rto = crtt + max(2 * crtt, tcp_rto_min(sk));
 506         } else if (tp->srtt_us == 0) {
 507                 /* RFC6298: 5.7 We've failed to get a valid RTT sample from
 508                  * 3WHS. This is most likely due to retransmission,
 509                  * including spurious one. Reset the RTO back to 3secs
 510                  * from the more aggressive 1sec to avoid more spurious
 511                  * retransmission.
 512                  */
 513                 tp->rttvar_us = jiffies_to_usecs(TCP_TIMEOUT_FALLBACK);
 514                 tp->mdev_us = tp->mdev_max_us = tp->rttvar_us;
 515
 516                 inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
 517         }
 518         /* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
 519          * retransmitted. In light of RFC6298 more aggressive 1sec
 520          * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
 521          * retransmission has occurred.
 522          */
 523         if (tp->total_retrans > 1)
 524                 tp->snd_cwnd = 1;
 525         else
 526                 tp->snd_cwnd = tcp_init_cwnd(tp, dst);
 527         tp->snd_cwnd_stamp = tcp_jiffies32;
 528 }
 529
 530 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst)
 531 {
 532         struct tcp_metrics_block *tm;
 533         bool ret;
 534
 535         if (!dst)
 536                 return false;
 537
 538         rcu_read_lock();
 539         tm = __tcp_get_metrics_req(req, dst);
 540         if (tm && tcp_metric_get(tm, TCP_METRIC_RTT))
 541                 ret = true;
 542         else
 543                 ret = false;
 544         rcu_read_unlock();
 545
 546         return ret;
 547 }
 548
 549 static DEFINE_SEQLOCK(fastopen_seqlock);
 550
 551 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
 552                             struct tcp_fastopen_cookie *cookie,
 553                             int *syn_loss, unsigned long *last_syn_loss)
 554 {
 555         struct tcp_metrics_block *tm;
 556
 557         rcu_read_lock();
 558         tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
 559         if (tm) {
 560                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 561                 unsigned int seq;
 562
 563                 do {
 564                         seq = read_seqbegin(&fastopen_seqlock);
 565                         if (tfom->mss)
 566                                 *mss = tfom->mss;
 567                         *cookie = tfom->cookie;
 568                         if (cookie->len <= 0 && tfom->try_exp == 1)
 569                                 cookie->exp = true;
 570                         *syn_loss = tfom->syn_loss;
 571                         *last_syn_loss = *syn_loss ? tfom->last_syn_loss : 0;
 572                 } while (read_seqretry(&fastopen_seqlock, seq));
 573         }
 574         rcu_read_unlock();
 575 }
 576
 577 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
 578                             struct tcp_fastopen_cookie *cookie, bool syn_lost,
 579                             u16 try_exp)
 580 {
 581         struct dst_entry *dst = __sk_dst_get(sk);
 582         struct tcp_metrics_block *tm;
 583
 584         if (!dst)
 585                 return;
 586         rcu_read_lock();
 587         tm = tcp_get_metrics(sk, dst, true);
 588         if (tm) {
 589                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 590
 591                 write_seqlock_bh(&fastopen_seqlock);
 592                 if (mss)
 593                         tfom->mss = mss;
 594                 if (cookie && cookie->len > 0)
 595                         tfom->cookie = *cookie;
 596                 else if (try_exp > tfom->try_exp &&
 597                          tfom->cookie.len <= 0 && !tfom->cookie.exp)
 598                         tfom->try_exp = try_exp;
 599                 if (syn_lost) {
 600                         ++tfom->syn_loss;
 601                         tfom->last_syn_loss = jiffies;
 602                 } else
 603                         tfom->syn_loss = 0;
 604                 write_sequnlock_bh(&fastopen_seqlock);
 605         }
 606         rcu_read_unlock();
 607 }
 608
 609 static struct genl_family tcp_metrics_nl_family;
 610
 611 static const struct nla_policy tcp_metrics_nl_policy[TCP_METRICS_ATTR_MAX + 1] = {
 612         [TCP_METRICS_ATTR_ADDR_IPV4]    = { .type = NLA_U32, },
 613         [TCP_METRICS_ATTR_ADDR_IPV6]    = { .type = NLA_BINARY,
 614                                             .len = sizeof(struct in6_addr), },
 615         /* Following attributes are not received for GET/DEL,
 616          * we keep them for reference
 617          */
 618 #if 0
 619         [TCP_METRICS_ATTR_AGE]          = { .type = NLA_MSECS, },
 620         [TCP_METRICS_ATTR_TW_TSVAL]     = { .type = NLA_U32, },
 621         [TCP_METRICS_ATTR_TW_TS_STAMP]  = { .type = NLA_S32, },
 622         [TCP_METRICS_ATTR_VALS]         = { .type = NLA_NESTED, },
 623         [TCP_METRICS_ATTR_FOPEN_MSS]    = { .type = NLA_U16, },
 624         [TCP_METRICS_ATTR_FOPEN_SYN_DROPS]      = { .type = NLA_U16, },
 625         [TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS]    = { .type = NLA_MSECS, },
 626         [TCP_METRICS_ATTR_FOPEN_COOKIE] = { .type = NLA_BINARY,
 627                                             .len = TCP_FASTOPEN_COOKIE_MAX, },
 628 #endif
 629 };
 630
 631 /* Add attributes, caller cancels its header on failure */
 632 static int tcp_metrics_fill_info(struct sk_buff *msg,
 633                                  struct tcp_metrics_block *tm)
 634 {
 635         struct nlattr *nest;
 636         int i;
 637
 638         switch (tm->tcpm_daddr.family) {
 639         case AF_INET:
 640                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_ADDR_IPV4,
 641                                     inetpeer_get_addr_v4(&tm->tcpm_daddr)) < 0)
 642                         goto nla_put_failure;
 643                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_SADDR_IPV4,
 644                                     inetpeer_get_addr_v4(&tm->tcpm_saddr)) < 0)
 645                         goto nla_put_failure;
 646                 break;
 647         case AF_INET6:
 648                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_ADDR_IPV6,
 649                                      inetpeer_get_addr_v6(&tm->tcpm_daddr)) < 0)
 650                         goto nla_put_failure;
 651                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_SADDR_IPV6,
 652                                      inetpeer_get_addr_v6(&tm->tcpm_saddr)) < 0)
 653                         goto nla_put_failure;
 654                 break;
 655         default:
 656                 return -EAFNOSUPPORT;
 657         }
 658
 659         if (nla_put_msecs(msg, TCP_METRICS_ATTR_AGE,
 660                           jiffies - tm->tcpm_stamp,
 661                           TCP_METRICS_ATTR_PAD) < 0)
 662                 goto nla_put_failure;
 663
 664         {
 665                 int n = 0;
 666
 667                 nest = nla_nest_start(msg, TCP_METRICS_ATTR_VALS);
 668                 if (!nest)
 669                         goto nla_put_failure;
 670                 for (i = 0; i < TCP_METRIC_MAX_KERNEL + 1; i++) {
 671                         u32 val = tm->tcpm_vals[i];
 672
 673                         if (!val)
 674                                 continue;
 675                         if (i == TCP_METRIC_RTT) {
 676                                 if (nla_put_u32(msg, TCP_METRIC_RTT_US + 1,
 677                                                 val) < 0)
 678                                         goto nla_put_failure;
 679                                 n++;
 680                                 val = max(val / 1000, 1U);
 681                         }
 682                         if (i == TCP_METRIC_RTTVAR) {
 683                                 if (nla_put_u32(msg, TCP_METRIC_RTTVAR_US + 1,
 684                                                 val) < 0)
 685                                         goto nla_put_failure;
 686                                 n++;
 687                                 val = max(val / 1000, 1U);
 688                         }
 689                         if (nla_put_u32(msg, i + 1, val) < 0)
 690                                 goto nla_put_failure;
 691                         n++;
 692                 }
 693                 if (n)
 694                         nla_nest_end(msg, nest);
 695                 else
 696                         nla_nest_cancel(msg, nest);
 697         }
 698
 699         {
 700                 struct tcp_fastopen_metrics tfom_copy[1], *tfom;
 701                 unsigned int seq;
 702
 703                 do {
 704                         seq = read_seqbegin(&fastopen_seqlock);
 705                         tfom_copy[0] = tm->tcpm_fastopen;
 706                 } while (read_seqretry(&fastopen_seqlock, seq));
 707
 708                 tfom = tfom_copy;
 709                 if (tfom->mss &&
 710                     nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_MSS,
 711                                 tfom->mss) < 0)
 712                         goto nla_put_failure;
 713                 if (tfom->syn_loss &&
 714                     (nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROPS,
 715                                 tfom->syn_loss) < 0 ||
 716                      nla_put_msecs(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS,
 717                                 jiffies - tfom->last_syn_loss,
 718                                 TCP_METRICS_ATTR_PAD) < 0))
 719                         goto nla_put_failure;
 720                 if (tfom->cookie.len > 0 &&
 721                     nla_put(msg, TCP_METRICS_ATTR_FOPEN_COOKIE,
 722                             tfom->cookie.len, tfom->cookie.val) < 0)
 723                         goto nla_put_failure;
 724         }
 725
 726         return 0;
 727
 728 nla_put_failure:
 729         return -EMSGSIZE;
 730 }
 731
 732 static int tcp_metrics_dump_info(struct sk_buff *skb,
 733                                  struct netlink_callback *cb,
 734                                  struct tcp_metrics_block *tm)
 735 {
 736         void *hdr;
 737
 738         hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
 739                           &tcp_metrics_nl_family, NLM_F_MULTI,
 740                           TCP_METRICS_CMD_GET);
 741         if (!hdr)
 742                 return -EMSGSIZE;
 743
 744         if (tcp_metrics_fill_info(skb, tm) < 0)
 745                 goto nla_put_failure;
 746
 747         genlmsg_end(skb, hdr);
 748         return 0;
 749
 750 nla_put_failure:
 751         genlmsg_cancel(skb, hdr);
 752         return -EMSGSIZE;
 753 }
 754
 755 static int tcp_metrics_nl_dump(struct sk_buff *skb,
 756                                struct netlink_callback *cb)
 757 {
 758         struct net *net = sock_net(skb->sk);
 759         unsigned int max_rows = 1U << tcp_metrics_hash_log;
 760         unsigned int row, s_row = cb->args[0];
 761         int s_col = cb->args[1], col = s_col;
 762
 763         for (row = s_row; row < max_rows; row++, s_col = 0) {
 764                 struct tcp_metrics_block *tm;
 765                 struct tcpm_hash_bucket *hb = tcp_metrics_hash + row;
 766
 767                 rcu_read_lock();
 768                 for (col = 0, tm = rcu_dereference(hb->chain); tm;
 769                      tm = rcu_dereference(tm->tcpm_next), col++) {
 770                         if (!net_eq(tm_net(tm), net))
 771                                 continue;
 772                         if (col < s_col)
 773                                 continue;
 774                         if (tcp_metrics_dump_info(skb, cb, tm) < 0) {
 775                                 rcu_read_unlock();
 776                                 goto done;
 777                         }
 778                 }
 779                 rcu_read_unlock();
 780         }
 781
 782 done:
 783         cb->args[0] = row;
 784         cb->args[1] = col;
 785         return skb->len;
 786 }
 787
 788 static int __parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 789                            unsigned int *hash, int optional, int v4, int v6)
 790 {
 791         struct nlattr *a;
 792
 793         a = info->attrs[v4];
 794         if (a) {
 795                 inetpeer_set_addr_v4(addr, nla_get_in_addr(a));
 796                 if (hash)
 797                         *hash = ipv4_addr_hash(inetpeer_get_addr_v4(addr));
 798                 return 0;
 799         }
 800         a = info->attrs[v6];
 801         if (a) {
 802                 struct in6_addr in6;
 803
 804                 if (nla_len(a) != sizeof(struct in6_addr))
 805                         return -EINVAL;
 806                 in6 = nla_get_in6_addr(a);
 807                 inetpeer_set_addr_v6(addr, &in6);
 808                 if (hash)
 809                         *hash = ipv6_addr_hash(inetpeer_get_addr_v6(addr));
 810                 return 0;
 811         }
 812         return optional ? 1 : -EAFNOSUPPORT;
 813 }
 814
 815 static int parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 816                          unsigned int *hash, int optional)
 817 {
 818         return __parse_nl_addr(info, addr, hash, optional,
 819                                TCP_METRICS_ATTR_ADDR_IPV4,
 820                                TCP_METRICS_ATTR_ADDR_IPV6);
 821 }
 822
 823 static int parse_nl_saddr(struct genl_info *info, struct inetpeer_addr *addr)
 824 {
 825         return __parse_nl_addr(info, addr, NULL, 0,
 826                                TCP_METRICS_ATTR_SADDR_IPV4,
 827                                TCP_METRICS_ATTR_SADDR_IPV6);
 828 }
 829
 830 static int tcp_metrics_nl_cmd_get(struct sk_buff *skb, struct genl_info *info)
 831 {
 832         struct tcp_metrics_block *tm;
 833         struct inetpeer_addr saddr, daddr;
 834         unsigned int hash;
 835         struct sk_buff *msg;
 836         struct net *net = genl_info_net(info);
 837         void *reply;
 838         int ret;
 839         bool src = true;
 840
 841         ret = parse_nl_addr(info, &daddr, &hash, 0);
 842         if (ret < 0)
 843                 return ret;
 844
 845         ret = parse_nl_saddr(info, &saddr);
 846         if (ret < 0)
 847                 src = false;
 848
 849         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 850         if (!msg)
 851                 return -ENOMEM;
 852
 853         reply = genlmsg_put_reply(msg, info, &tcp_metrics_nl_family, 0,
 854                                   info->genlhdr->cmd);
 855         if (!reply)
 856                 goto nla_put_failure;
 857
 858         hash ^= net_hash_mix(net);
 859         hash = hash_32(hash, tcp_metrics_hash_log);
 860         ret = -ESRCH;
 861         rcu_read_lock();
 862         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
 863              tm = rcu_dereference(tm->tcpm_next)) {
 864                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
 865                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
 866                     net_eq(tm_net(tm), net)) {
 867                         ret = tcp_metrics_fill_info(msg, tm);
 868                         break;
 869                 }
 870         }
 871         rcu_read_unlock();
 872         if (ret < 0)
 873                 goto out_free;
 874
 875         genlmsg_end(msg, reply);
 876         return genlmsg_reply(msg, info);
 877
 878 nla_put_failure:
 879         ret = -EMSGSIZE;
 880
 881 out_free:
 882         nlmsg_free(msg);
 883         return ret;
 884 }
 885
 886 static void tcp_metrics_flush_all(struct net *net)
 887 {
 888         unsigned int max_rows = 1U << tcp_metrics_hash_log;
 889         struct tcpm_hash_bucket *hb = tcp_metrics_hash;
 890         struct tcp_metrics_block *tm;
 891         unsigned int row;
 892
 893         for (row = 0; row < max_rows; row++, hb++) {
 894                 struct tcp_metrics_block __rcu **pp;
 895                 spin_lock_bh(&tcp_metrics_lock);
 896                 pp = &hb->chain;
 897                 for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
 898                         if (net_eq(tm_net(tm), net)) {
 899                                 *pp = tm->tcpm_next;
 900                                 kfree_rcu(tm, rcu_head);
 901                         } else {
 902                                 pp = &tm->tcpm_next;
 903                         }
 904                 }
 905                 spin_unlock_bh(&tcp_metrics_lock);
 906         }
 907 }
 908
 909 static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info)
 910 {
 911         struct tcpm_hash_bucket *hb;
 912         struct tcp_metrics_block *tm;
 913         struct tcp_metrics_block __rcu **pp;
 914         struct inetpeer_addr saddr, daddr;
 915         unsigned int hash;
 916         struct net *net = genl_info_net(info);
 917         int ret;
 918         bool src = true, found = false;
 919
 920         ret = parse_nl_addr(info, &daddr, &hash, 1);
 921         if (ret < 0)
 922                 return ret;
 923         if (ret > 0) {
 924                 tcp_metrics_flush_all(net);
 925                 return 0;
 926         }
 927         ret = parse_nl_saddr(info, &saddr);
 928         if (ret < 0)
 929                 src = false;
 930
 931         hash ^= net_hash_mix(net);
 932         hash = hash_32(hash, tcp_metrics_hash_log);
 933         hb = tcp_metrics_hash + hash;
 934         pp = &hb->chain;
 935         spin_lock_bh(&tcp_metrics_lock);
 936         for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
 937                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
 938                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
 939                     net_eq(tm_net(tm), net)) {
 940                         *pp = tm->tcpm_next;
 941                         kfree_rcu(tm, rcu_head);
 942                         found = true;
 943                 } else {
 944                         pp = &tm->tcpm_next;
 945                 }
 946         }
 947         spin_unlock_bh(&tcp_metrics_lock);
 948         if (!found)
 949                 return -ESRCH;
 950         return 0;
 951 }
 952
 953 static const struct genl_ops tcp_metrics_nl_ops[] = {
 954         {
 955                 .cmd = TCP_METRICS_CMD_GET,
 956                 .doit = tcp_metrics_nl_cmd_get,
 957                 .dumpit = tcp_metrics_nl_dump,
 958                 .policy = tcp_metrics_nl_policy,
 959         },
 960         {
 961                 .cmd = TCP_METRICS_CMD_DEL,
 962                 .doit = tcp_metrics_nl_cmd_del,
 963                 .policy = tcp_metrics_nl_policy,
 964                 .flags = GENL_ADMIN_PERM,
 965         },
 966 };
 967
 968 static struct genl_family tcp_metrics_nl_family __ro_after_init = {
 969         .hdrsize        = 0,
 970         .name           = TCP_METRICS_GENL_NAME,
 971         .version        = TCP_METRICS_GENL_VERSION,
 972         .maxattr        = TCP_METRICS_ATTR_MAX,
 973         .netnsok        = true,
 974         .module         = THIS_MODULE,
 975         .ops            = tcp_metrics_nl_ops,
 976         .n_ops          = ARRAY_SIZE(tcp_metrics_nl_ops),
 977 };
 978
 979 static unsigned int tcpmhash_entries;
 980 static int __init set_tcpmhash_entries(char *str)
 981 {
 982         ssize_t ret;
 983
 984         if (!str)
 985                 return 0;
 986
 987         ret = kstrtouint(str, 0, &tcpmhash_entries);
 988         if (ret)
 989                 return 0;
 990
 991         return 1;
 992 }
 993 __setup("tcpmhash_entries=", set_tcpmhash_entries);
 994
 995 static int __net_init tcp_net_metrics_init(struct net *net)
 996 {
 997         size_t size;
 998         unsigned int slots;
 999
1000         if (!net_eq(net, &init_net))
1001                 return 0;
1002
1003         slots = tcpmhash_entries;
1004         if (!slots) {
1005                 if (totalram_pages >= 128 * 1024)
1006                         slots = 16 * 1024;
1007                 else
1008                         slots = 8 * 1024;
1009         }
1010
1011         tcp_metrics_hash_log = order_base_2(slots);
1012         size = sizeof(struct tcpm_hash_bucket) << tcp_metrics_hash_log;
1013
1014         tcp_metrics_hash = kvzalloc(size, GFP_KERNEL);
1015         if (!tcp_metrics_hash)
1016                 return -ENOMEM;
1017
1018         return 0;
1019 }
1020
1021 static void __net_exit tcp_net_metrics_exit(struct net *net)
1022 {
1023         tcp_metrics_flush_all(net);
1024 }
1025
1026 static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
1027         .init   =       tcp_net_metrics_init,
1028         .exit   =       tcp_net_metrics_exit,
1029 };
1030
1031 void __init tcp_metrics_init(void)
1032 {
1033         int ret;
1034
1035         ret = register_pernet_subsys(&tcp_net_metrics_ops);
1036         if (ret < 0)
1037                 panic("Could not allocate the tcp_metrics hash table\n");
1038
1039         ret = genl_register_family(&tcp_metrics_nl_family);
1040         if (ret < 0)
1041                 panic("Could not register tcp_metrics generic netlink\n");
1042 }