net/ipv4/tcp_metrics.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/rcupdate.h>
   3 #include <linux/spinlock.h>
   4 #include <linux/jiffies.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 #include <linux/vmalloc.h>
  13
  14 #include <net/inet_connection_sock.h>
  15 #include <net/net_namespace.h>
  16 #include <net/request_sock.h>
  17 #include <net/inetpeer.h>
  18 #include <net/sock.h>
  19 #include <net/ipv6.h>
  20 #include <net/dst.h>
  21 #include <net/tcp.h>
  22 #include <net/genetlink.h>
  23
  24 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
  25                                                    const struct inetpeer_addr *daddr,
  26                                                    struct net *net, unsigned int hash);
  27
  28 struct tcp_fastopen_metrics {
  29         u16     mss;
  30         u16     syn_loss:10,            /* Recurring Fast Open SYN losses */
  31                 try_exp:2;              /* Request w/ exp. option (once) */
  32         unsigned long   last_syn_loss;  /* Last Fast Open SYN loss */
  33         struct  tcp_fastopen_cookie     cookie;
  34 };
  35
  36 /* TCP_METRIC_MAX includes 2 extra fields for userspace compatibility
  37  * Kernel only stores RTT and RTTVAR in usec resolution
  38  */
  39 #define TCP_METRIC_MAX_KERNEL (TCP_METRIC_MAX - 2)
  40
  41 struct tcp_metrics_block {
  42         struct tcp_metrics_block __rcu  *tcpm_next;
  43         possible_net_t                  tcpm_net;
  44         struct inetpeer_addr            tcpm_saddr;
  45         struct inetpeer_addr            tcpm_daddr;
  46         unsigned long                   tcpm_stamp;
  47         u32                             tcpm_lock;
  48         u32                             tcpm_vals[TCP_METRIC_MAX_KERNEL + 1];
  49         struct tcp_fastopen_metrics     tcpm_fastopen;
  50
  51         struct rcu_head                 rcu_head;
  52 };
  53
  54 static inline struct net *tm_net(struct tcp_metrics_block *tm)
  55 {
  56         return read_pnet(&tm->tcpm_net);
  57 }
  58
  59 static bool tcp_metric_locked(struct tcp_metrics_block *tm,
  60                               enum tcp_metric_index idx)
  61 {
  62         return tm->tcpm_lock & (1 << idx);
  63 }
  64
  65 static u32 tcp_metric_get(struct tcp_metrics_block *tm,
  66                           enum tcp_metric_index idx)
  67 {
  68         return tm->tcpm_vals[idx];
  69 }
  70
  71 static void tcp_metric_set(struct tcp_metrics_block *tm,
  72                            enum tcp_metric_index idx,
  73                            u32 val)
  74 {
  75         tm->tcpm_vals[idx] = val;
  76 }
  77
  78 static bool addr_same(const struct inetpeer_addr *a,
  79                       const struct inetpeer_addr *b)
  80 {
  81         return inetpeer_addr_cmp(a, b) == 0;
  82 }
  83
  84 struct tcpm_hash_bucket {
  85         struct tcp_metrics_block __rcu  *chain;
  86 };
  87
  88 static struct tcpm_hash_bucket  *tcp_metrics_hash __read_mostly;
  89 static unsigned int             tcp_metrics_hash_log __read_mostly;
  90
  91 static DEFINE_SPINLOCK(tcp_metrics_lock);
  92
  93 static void tcpm_suck_dst(struct tcp_metrics_block *tm,
  94                           const struct dst_entry *dst,
  95                           bool fastopen_clear)
  96 {
  97         u32 msval;
  98         u32 val;
  99
 100         tm->tcpm_stamp = jiffies;
 101
 102         val = 0;
 103         if (dst_metric_locked(dst, RTAX_RTT))
 104                 val |= 1 << TCP_METRIC_RTT;
 105         if (dst_metric_locked(dst, RTAX_RTTVAR))
 106                 val |= 1 << TCP_METRIC_RTTVAR;
 107         if (dst_metric_locked(dst, RTAX_SSTHRESH))
 108                 val |= 1 << TCP_METRIC_SSTHRESH;
 109         if (dst_metric_locked(dst, RTAX_CWND))
 110                 val |= 1 << TCP_METRIC_CWND;
 111         if (dst_metric_locked(dst, RTAX_REORDERING))
 112                 val |= 1 << TCP_METRIC_REORDERING;
 113         tm->tcpm_lock = val;
 114
 115         msval = dst_metric_raw(dst, RTAX_RTT);
 116         tm->tcpm_vals[TCP_METRIC_RTT] = msval * USEC_PER_MSEC;
 117
 118         msval = dst_metric_raw(dst, RTAX_RTTVAR);
 119         tm->tcpm_vals[TCP_METRIC_RTTVAR] = msval * USEC_PER_MSEC;
 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         if (fastopen_clear) {
 124                 tm->tcpm_fastopen.mss = 0;
 125                 tm->tcpm_fastopen.syn_loss = 0;
 126                 tm->tcpm_fastopen.try_exp = 0;
 127                 tm->tcpm_fastopen.cookie.exp = false;
 128                 tm->tcpm_fastopen.cookie.len = 0;
 129         }
 130 }
 131
 132 #define TCP_METRICS_TIMEOUT             (60 * 60 * HZ)
 133
 134 static void tcpm_check_stamp(struct tcp_metrics_block *tm, struct dst_entry *dst)
 135 {
 136         if (tm && unlikely(time_after(jiffies, tm->tcpm_stamp + TCP_METRICS_TIMEOUT)))
 137                 tcpm_suck_dst(tm, dst, false);
 138 }
 139
 140 #define TCP_METRICS_RECLAIM_DEPTH       5
 141 #define TCP_METRICS_RECLAIM_PTR         (struct tcp_metrics_block *) 0x1UL
 142
 143 #define deref_locked(p) \
 144         rcu_dereference_protected(p, lockdep_is_held(&tcp_metrics_lock))
 145
 146 static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
 147                                           struct inetpeer_addr *saddr,
 148                                           struct inetpeer_addr *daddr,
 149                                           unsigned int hash)
 150 {
 151         struct tcp_metrics_block *tm;
 152         struct net *net;
 153         bool reclaim = false;
 154
 155         spin_lock_bh(&tcp_metrics_lock);
 156         net = dev_net(dst->dev);
 157
 158         /* While waiting for the spin-lock the cache might have been populated
 159          * with this entry and so we have to check again.
 160          */
 161         tm = __tcp_get_metrics(saddr, daddr, net, hash);
 162         if (tm == TCP_METRICS_RECLAIM_PTR) {
 163                 reclaim = true;
 164                 tm = NULL;
 165         }
 166         if (tm) {
 167                 tcpm_check_stamp(tm, dst);
 168                 goto out_unlock;
 169         }
 170
 171         if (unlikely(reclaim)) {
 172                 struct tcp_metrics_block *oldest;
 173
 174                 oldest = deref_locked(tcp_metrics_hash[hash].chain);
 175                 for (tm = deref_locked(oldest->tcpm_next); tm;
 176                      tm = deref_locked(tm->tcpm_next)) {
 177                         if (time_before(tm->tcpm_stamp, oldest->tcpm_stamp))
 178                                 oldest = tm;
 179                 }
 180                 tm = oldest;
 181         } else {
 182                 tm = kmalloc(sizeof(*tm), GFP_ATOMIC);
 183                 if (!tm)
 184                         goto out_unlock;
 185         }
 186         write_pnet(&tm->tcpm_net, net);
 187         tm->tcpm_saddr = *saddr;
 188         tm->tcpm_daddr = *daddr;
 189
 190         tcpm_suck_dst(tm, dst, true);
 191
 192         if (likely(!reclaim)) {
 193                 tm->tcpm_next = tcp_metrics_hash[hash].chain;
 194                 rcu_assign_pointer(tcp_metrics_hash[hash].chain, tm);
 195         }
 196
 197 out_unlock:
 198         spin_unlock_bh(&tcp_metrics_lock);
 199         return tm;
 200 }
 201
 202 static struct tcp_metrics_block *tcp_get_encode(struct tcp_metrics_block *tm, int depth)
 203 {
 204         if (tm)
 205                 return tm;
 206         if (depth > TCP_METRICS_RECLAIM_DEPTH)
 207                 return TCP_METRICS_RECLAIM_PTR;
 208         return NULL;
 209 }
 210
 211 static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
 212                                                    const struct inetpeer_addr *daddr,
 213                                                    struct net *net, unsigned int hash)
 214 {
 215         struct tcp_metrics_block *tm;
 216         int depth = 0;
 217
 218         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
 219              tm = rcu_dereference(tm->tcpm_next)) {
 220                 if (addr_same(&tm->tcpm_saddr, saddr) &&
 221                     addr_same(&tm->tcpm_daddr, daddr) &&
 222                     net_eq(tm_net(tm), net))
 223                         break;
 224                 depth++;
 225         }
 226         return tcp_get_encode(tm, depth);
 227 }
 228
 229 static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
 230                                                        struct dst_entry *dst)
 231 {
 232         struct tcp_metrics_block *tm;
 233         struct inetpeer_addr saddr, daddr;
 234         unsigned int hash;
 235         struct net *net;
 236
 237         saddr.family = req->rsk_ops->family;
 238         daddr.family = req->rsk_ops->family;
 239         switch (daddr.family) {
 240         case AF_INET:
 241                 inetpeer_set_addr_v4(&saddr, inet_rsk(req)->ir_loc_addr);
 242                 inetpeer_set_addr_v4(&daddr, inet_rsk(req)->ir_rmt_addr);
 243                 hash = ipv4_addr_hash(inet_rsk(req)->ir_rmt_addr);
 244                 break;
 245 #if IS_ENABLED(CONFIG_IPV6)
 246         case AF_INET6:
 247                 inetpeer_set_addr_v6(&saddr, &inet_rsk(req)->ir_v6_loc_addr);
 248                 inetpeer_set_addr_v6(&daddr, &inet_rsk(req)->ir_v6_rmt_addr);
 249                 hash = ipv6_addr_hash(&inet_rsk(req)->ir_v6_rmt_addr);
 250                 break;
 251 #endif
 252         default:
 253                 return NULL;
 254         }
 255
 256         net = dev_net(dst->dev);
 257         hash ^= net_hash_mix(net);
 258         hash = hash_32(hash, tcp_metrics_hash_log);
 259
 260         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
 261              tm = rcu_dereference(tm->tcpm_next)) {
 262                 if (addr_same(&tm->tcpm_saddr, &saddr) &&
 263                     addr_same(&tm->tcpm_daddr, &daddr) &&
 264                     net_eq(tm_net(tm), net))
 265                         break;
 266         }
 267         tcpm_check_stamp(tm, dst);
 268         return tm;
 269 }
 270
 271 static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
 272                                                  struct dst_entry *dst,
 273                                                  bool create)
 274 {
 275         struct tcp_metrics_block *tm;
 276         struct inetpeer_addr saddr, daddr;
 277         unsigned int hash;
 278         struct net *net;
 279
 280         if (sk->sk_family == AF_INET) {
 281                 inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
 282                 inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
 283                 hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
 284         }
 285 #if IS_ENABLED(CONFIG_IPV6)
 286         else if (sk->sk_family == AF_INET6) {
 287                 if (ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
 288                         inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
 289                         inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
 290                         hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
 291                 } else {
 292                         inetpeer_set_addr_v6(&saddr, &sk->sk_v6_rcv_saddr);
 293                         inetpeer_set_addr_v6(&daddr, &sk->sk_v6_daddr);
 294                         hash = ipv6_addr_hash(&sk->sk_v6_daddr);
 295                 }
 296         }
 297 #endif
 298         else
 299                 return NULL;
 300
 301         net = dev_net(dst->dev);
 302         hash ^= net_hash_mix(net);
 303         hash = hash_32(hash, tcp_metrics_hash_log);
 304
 305         tm = __tcp_get_metrics(&saddr, &daddr, net, hash);
 306         if (tm == TCP_METRICS_RECLAIM_PTR)
 307                 tm = NULL;
 308         if (!tm && create)
 309                 tm = tcpm_new(dst, &saddr, &daddr, hash);
 310         else
 311                 tcpm_check_stamp(tm, dst);
 312
 313         return tm;
 314 }
 315
 316 /* Save metrics learned by this TCP session.  This function is called
 317  * only, when TCP finishes successfully i.e. when it enters TIME-WAIT
 318  * or goes from LAST-ACK to CLOSE.
 319  */
 320 void tcp_update_metrics(struct sock *sk)
 321 {
 322         const struct inet_connection_sock *icsk = inet_csk(sk);
 323         struct dst_entry *dst = __sk_dst_get(sk);
 324         struct tcp_sock *tp = tcp_sk(sk);
 325         struct net *net = sock_net(sk);
 326         struct tcp_metrics_block *tm;
 327         unsigned long rtt;
 328         u32 val;
 329         int m;
 330
 331         sk_dst_confirm(sk);
 332         if (net->ipv4.sysctl_tcp_nometrics_save || !dst)
 333                 return;
 334
 335         rcu_read_lock();
 336         if (icsk->icsk_backoff || !tp->srtt_us) {
 337                 /* This session failed to estimate rtt. Why?
 338                  * Probably, no packets returned in time.  Reset our
 339                  * results.
 340                  */
 341                 tm = tcp_get_metrics(sk, dst, false);
 342                 if (tm && !tcp_metric_locked(tm, TCP_METRIC_RTT))
 343                         tcp_metric_set(tm, TCP_METRIC_RTT, 0);
 344                 goto out_unlock;
 345         } else
 346                 tm = tcp_get_metrics(sk, dst, true);
 347
 348         if (!tm)
 349                 goto out_unlock;
 350
 351         rtt = tcp_metric_get(tm, TCP_METRIC_RTT);
 352         m = rtt - tp->srtt_us;
 353
 354         /* If newly calculated rtt larger than stored one, store new
 355          * one. Otherwise, use EWMA. Remember, rtt overestimation is
 356          * always better than underestimation.
 357          */
 358         if (!tcp_metric_locked(tm, TCP_METRIC_RTT)) {
 359                 if (m <= 0)
 360                         rtt = tp->srtt_us;
 361                 else
 362                         rtt -= (m >> 3);
 363                 tcp_metric_set(tm, TCP_METRIC_RTT, rtt);
 364         }
 365
 366         if (!tcp_metric_locked(tm, TCP_METRIC_RTTVAR)) {
 367                 unsigned long var;
 368
 369                 if (m < 0)
 370                         m = -m;
 371
 372                 /* Scale deviation to rttvar fixed point */
 373                 m >>= 1;
 374                 if (m < tp->mdev_us)
 375                         m = tp->mdev_us;
 376
 377                 var = tcp_metric_get(tm, TCP_METRIC_RTTVAR);
 378                 if (m >= var)
 379                         var = m;
 380                 else
 381                         var -= (var - m) >> 2;
 382
 383                 tcp_metric_set(tm, TCP_METRIC_RTTVAR, var);
 384         }
 385
 386         if (tcp_in_initial_slowstart(tp)) {
 387                 /* Slow start still did not finish. */
 388                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 389                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 390                         if (val && (tp->snd_cwnd >> 1) > val)
 391                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 392                                                tp->snd_cwnd >> 1);
 393                 }
 394                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 395                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 396                         if (tp->snd_cwnd > val)
 397                                 tcp_metric_set(tm, TCP_METRIC_CWND,
 398                                                tp->snd_cwnd);
 399                 }
 400         } else if (!tcp_in_slow_start(tp) &&
 401                    icsk->icsk_ca_state == TCP_CA_Open) {
 402                 /* Cong. avoidance phase, cwnd is reliable. */
 403                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
 404                         tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 405                                        max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
 406                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 407                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 408                         tcp_metric_set(tm, TCP_METRIC_CWND, (val + tp->snd_cwnd) >> 1);
 409                 }
 410         } else {
 411                 /* Else slow start did not finish, cwnd is non-sense,
 412                  * ssthresh may be also invalid.
 413                  */
 414                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 415                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 416                         tcp_metric_set(tm, TCP_METRIC_CWND,
 417                                        (val + tp->snd_ssthresh) >> 1);
 418                 }
 419                 if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 420                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 421                         if (val && tp->snd_ssthresh > val)
 422                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 423                                                tp->snd_ssthresh);
 424                 }
 425                 if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {
 426                         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 427                         if (val < tp->reordering &&
 428                             tp->reordering != net->ipv4.sysctl_tcp_reordering)
 429                                 tcp_metric_set(tm, TCP_METRIC_REORDERING,
 430                                                tp->reordering);
 431                 }
 432         }
 433         tm->tcpm_stamp = jiffies;
 434 out_unlock:
 435         rcu_read_unlock();
 436 }
 437
 438 /* Initialize metrics on socket. */
 439
 440 void tcp_init_metrics(struct sock *sk)
 441 {
 442         struct dst_entry *dst = __sk_dst_get(sk);
 443         struct tcp_sock *tp = tcp_sk(sk);
 444         struct tcp_metrics_block *tm;
 445         u32 val, crtt = 0; /* cached RTT scaled by 8 */
 446
 447         sk_dst_confirm(sk);
 448         if (!dst)
 449                 goto reset;
 450
 451         rcu_read_lock();
 452         tm = tcp_get_metrics(sk, dst, true);
 453         if (!tm) {
 454                 rcu_read_unlock();
 455                 goto reset;
 456         }
 457
 458         if (tcp_metric_locked(tm, TCP_METRIC_CWND))
 459                 tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
 460
 461         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 462         if (val) {
 463                 tp->snd_ssthresh = val;
 464                 if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
 465                         tp->snd_ssthresh = tp->snd_cwnd_clamp;
 466         } else {
 467                 /* ssthresh may have been reduced unnecessarily during.
 468                  * 3WHS. Restore it back to its initial default.
 469                  */
 470                 tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
 471         }
 472         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 473         if (val && tp->reordering != val)
 474                 tp->reordering = val;
 475
 476         crtt = tcp_metric_get(tm, TCP_METRIC_RTT);
 477         rcu_read_unlock();
 478 reset:
 479         /* The initial RTT measurement from the SYN/SYN-ACK is not ideal
 480          * to seed the RTO for later data packets because SYN packets are
 481          * small. Use the per-dst cached values to seed the RTO but keep
 482          * the RTT estimator variables intact (e.g., srtt, mdev, rttvar).
 483          * Later the RTO will be updated immediately upon obtaining the first
 484          * data RTT sample (tcp_rtt_estimator()). Hence the cached RTT only
 485          * influences the first RTO but not later RTT estimation.
 486          *
 487          * But if RTT is not available from the SYN (due to retransmits or
 488          * syn cookies) or the cache, force a conservative 3secs timeout.
 489          *
 490          * A bit of theory. RTT is time passed after "normal" sized packet
 491          * is sent until it is ACKed. In normal circumstances sending small
 492          * packets force peer to delay ACKs and calculation is correct too.
 493          * The algorithm is adaptive and, provided we follow specs, it
 494          * NEVER underestimate RTT. BUT! If peer tries to make some clever
 495          * tricks sort of "quick acks" for time long enough to decrease RTT
 496          * to low value, and then abruptly stops to do it and starts to delay
 497          * ACKs, wait for troubles.
 498          */
 499         if (crtt > tp->srtt_us) {
 500                 /* Set RTO like tcp_rtt_estimator(), but from cached RTT. */
 501                 crtt /= 8 * USEC_PER_SEC / HZ;
 502                 inet_csk(sk)->icsk_rto = crtt + max(2 * crtt, tcp_rto_min(sk));
 503         } else if (tp->srtt_us == 0) {
 504                 /* RFC6298: 5.7 We've failed to get a valid RTT sample from
 505                  * 3WHS. This is most likely due to retransmission,
 506                  * including spurious one. Reset the RTO back to 3secs
 507                  * from the more aggressive 1sec to avoid more spurious
 508                  * retransmission.
 509                  */
 510                 tp->rttvar_us = jiffies_to_usecs(TCP_TIMEOUT_FALLBACK);
 511                 tp->mdev_us = tp->mdev_max_us = tp->rttvar_us;
 512
 513                 inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
 514         }
 515         /* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
 516          * retransmitted. In light of RFC6298 more aggressive 1sec
 517          * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
 518          * retransmission has occurred.
 519          */
 520         if (tp->total_retrans > 1)
 521                 tp->snd_cwnd = 1;
 522         else
 523                 tp->snd_cwnd = tcp_init_cwnd(tp, dst);
 524         tp->snd_cwnd_stamp = tcp_jiffies32;
 525 }
 526
 527 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst)
 528 {
 529         struct tcp_metrics_block *tm;
 530         bool ret;
 531
 532         if (!dst)
 533                 return false;
 534
 535         rcu_read_lock();
 536         tm = __tcp_get_metrics_req(req, dst);
 537         if (tm && tcp_metric_get(tm, TCP_METRIC_RTT))
 538                 ret = true;
 539         else
 540                 ret = false;
 541         rcu_read_unlock();
 542
 543         return ret;
 544 }
 545
 546 static DEFINE_SEQLOCK(fastopen_seqlock);
 547
 548 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
 549                             struct tcp_fastopen_cookie *cookie)
 550 {
 551         struct tcp_metrics_block *tm;
 552
 553         rcu_read_lock();
 554         tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
 555         if (tm) {
 556                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 557                 unsigned int seq;
 558
 559                 do {
 560                         seq = read_seqbegin(&fastopen_seqlock);
 561                         if (tfom->mss)
 562                                 *mss = tfom->mss;
 563                         *cookie = tfom->cookie;
 564                         if (cookie->len <= 0 && tfom->try_exp == 1)
 565                                 cookie->exp = true;
 566                 } while (read_seqretry(&fastopen_seqlock, seq));
 567         }
 568         rcu_read_unlock();
 569 }
 570
 571 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
 572                             struct tcp_fastopen_cookie *cookie, bool syn_lost,
 573                             u16 try_exp)
 574 {
 575         struct dst_entry *dst = __sk_dst_get(sk);
 576         struct tcp_metrics_block *tm;
 577
 578         if (!dst)
 579                 return;
 580         rcu_read_lock();
 581         tm = tcp_get_metrics(sk, dst, true);
 582         if (tm) {
 583                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 584
 585                 write_seqlock_bh(&fastopen_seqlock);
 586                 if (mss)
 587                         tfom->mss = mss;
 588                 if (cookie && cookie->len > 0)
 589                         tfom->cookie = *cookie;
 590                 else if (try_exp > tfom->try_exp &&
 591                          tfom->cookie.len <= 0 && !tfom->cookie.exp)
 592                         tfom->try_exp = try_exp;
 593                 if (syn_lost) {
 594                         ++tfom->syn_loss;
 595                         tfom->last_syn_loss = jiffies;
 596                 } else
 597                         tfom->syn_loss = 0;
 598                 write_sequnlock_bh(&fastopen_seqlock);
 599         }
 600         rcu_read_unlock();
 601 }
 602
 603 static struct genl_family tcp_metrics_nl_family;
 604
 605 static const struct nla_policy tcp_metrics_nl_policy[TCP_METRICS_ATTR_MAX + 1] = {
 606         [TCP_METRICS_ATTR_ADDR_IPV4]    = { .type = NLA_U32, },
 607         [TCP_METRICS_ATTR_ADDR_IPV6]    = { .type = NLA_BINARY,
 608                                             .len = sizeof(struct in6_addr), },
 609         /* Following attributes are not received for GET/DEL,
 610          * we keep them for reference
 611          */
 612 #if 0
 613         [TCP_METRICS_ATTR_AGE]          = { .type = NLA_MSECS, },
 614         [TCP_METRICS_ATTR_TW_TSVAL]     = { .type = NLA_U32, },
 615         [TCP_METRICS_ATTR_TW_TS_STAMP]  = { .type = NLA_S32, },
 616         [TCP_METRICS_ATTR_VALS]         = { .type = NLA_NESTED, },
 617         [TCP_METRICS_ATTR_FOPEN_MSS]    = { .type = NLA_U16, },
 618         [TCP_METRICS_ATTR_FOPEN_SYN_DROPS]      = { .type = NLA_U16, },
 619         [TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS]    = { .type = NLA_MSECS, },
 620         [TCP_METRICS_ATTR_FOPEN_COOKIE] = { .type = NLA_BINARY,
 621                                             .len = TCP_FASTOPEN_COOKIE_MAX, },
 622 #endif
 623 };
 624
 625 /* Add attributes, caller cancels its header on failure */
 626 static int tcp_metrics_fill_info(struct sk_buff *msg,
 627                                  struct tcp_metrics_block *tm)
 628 {
 629         struct nlattr *nest;
 630         int i;
 631
 632         switch (tm->tcpm_daddr.family) {
 633         case AF_INET:
 634                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_ADDR_IPV4,
 635                                     inetpeer_get_addr_v4(&tm->tcpm_daddr)) < 0)
 636                         goto nla_put_failure;
 637                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_SADDR_IPV4,
 638                                     inetpeer_get_addr_v4(&tm->tcpm_saddr)) < 0)
 639                         goto nla_put_failure;
 640                 break;
 641         case AF_INET6:
 642                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_ADDR_IPV6,
 643                                      inetpeer_get_addr_v6(&tm->tcpm_daddr)) < 0)
 644                         goto nla_put_failure;
 645                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_SADDR_IPV6,
 646                                      inetpeer_get_addr_v6(&tm->tcpm_saddr)) < 0)
 647                         goto nla_put_failure;
 648                 break;
 649         default:
 650                 return -EAFNOSUPPORT;
 651         }
 652
 653         if (nla_put_msecs(msg, TCP_METRICS_ATTR_AGE,
 654                           jiffies - tm->tcpm_stamp,
 655                           TCP_METRICS_ATTR_PAD) < 0)
 656                 goto nla_put_failure;
 657
 658         {
 659                 int n = 0;
 660
 661                 nest = nla_nest_start(msg, TCP_METRICS_ATTR_VALS);
 662                 if (!nest)
 663                         goto nla_put_failure;
 664                 for (i = 0; i < TCP_METRIC_MAX_KERNEL + 1; i++) {
 665                         u32 val = tm->tcpm_vals[i];
 666
 667                         if (!val)
 668                                 continue;
 669                         if (i == TCP_METRIC_RTT) {
 670                                 if (nla_put_u32(msg, TCP_METRIC_RTT_US + 1,
 671                                                 val) < 0)
 672                                         goto nla_put_failure;
 673                                 n++;
 674                                 val = max(val / 1000, 1U);
 675                         }
 676                         if (i == TCP_METRIC_RTTVAR) {
 677                                 if (nla_put_u32(msg, TCP_METRIC_RTTVAR_US + 1,
 678                                                 val) < 0)
 679                                         goto nla_put_failure;
 680                                 n++;
 681                                 val = max(val / 1000, 1U);
 682                         }
 683                         if (nla_put_u32(msg, i + 1, val) < 0)
 684                                 goto nla_put_failure;
 685                         n++;
 686                 }
 687                 if (n)
 688                         nla_nest_end(msg, nest);
 689                 else
 690                         nla_nest_cancel(msg, nest);
 691         }
 692
 693         {
 694                 struct tcp_fastopen_metrics tfom_copy[1], *tfom;
 695                 unsigned int seq;
 696
 697                 do {
 698                         seq = read_seqbegin(&fastopen_seqlock);
 699                         tfom_copy[0] = tm->tcpm_fastopen;
 700                 } while (read_seqretry(&fastopen_seqlock, seq));
 701
 702                 tfom = tfom_copy;
 703                 if (tfom->mss &&
 704                     nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_MSS,
 705                                 tfom->mss) < 0)
 706                         goto nla_put_failure;
 707                 if (tfom->syn_loss &&
 708                     (nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROPS,
 709                                 tfom->syn_loss) < 0 ||
 710                      nla_put_msecs(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS,
 711                                 jiffies - tfom->last_syn_loss,
 712                                 TCP_METRICS_ATTR_PAD) < 0))
 713                         goto nla_put_failure;
 714                 if (tfom->cookie.len > 0 &&
 715                     nla_put(msg, TCP_METRICS_ATTR_FOPEN_COOKIE,
 716                             tfom->cookie.len, tfom->cookie.val) < 0)
 717                         goto nla_put_failure;
 718         }
 719
 720         return 0;
 721
 722 nla_put_failure:
 723         return -EMSGSIZE;
 724 }
 725
 726 static int tcp_metrics_dump_info(struct sk_buff *skb,
 727                                  struct netlink_callback *cb,
 728                                  struct tcp_metrics_block *tm)
 729 {
 730         void *hdr;
 731
 732         hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
 733                           &tcp_metrics_nl_family, NLM_F_MULTI,
 734                           TCP_METRICS_CMD_GET);
 735         if (!hdr)
 736                 return -EMSGSIZE;
 737
 738         if (tcp_metrics_fill_info(skb, tm) < 0)
 739                 goto nla_put_failure;
 740
 741         genlmsg_end(skb, hdr);
 742         return 0;
 743
 744 nla_put_failure:
 745         genlmsg_cancel(skb, hdr);
 746         return -EMSGSIZE;
 747 }
 748
 749 static int tcp_metrics_nl_dump(struct sk_buff *skb,
 750                                struct netlink_callback *cb)
 751 {
 752         struct net *net = sock_net(skb->sk);
 753         unsigned int max_rows = 1U << tcp_metrics_hash_log;
 754         unsigned int row, s_row = cb->args[0];
 755         int s_col = cb->args[1], col = s_col;
 756
 757         for (row = s_row; row < max_rows; row++, s_col = 0) {
 758                 struct tcp_metrics_block *tm;
 759                 struct tcpm_hash_bucket *hb = tcp_metrics_hash + row;
 760
 761                 rcu_read_lock();
 762                 for (col = 0, tm = rcu_dereference(hb->chain); tm;
 763                      tm = rcu_dereference(tm->tcpm_next), col++) {
 764                         if (!net_eq(tm_net(tm), net))
 765                                 continue;
 766                         if (col < s_col)
 767                                 continue;
 768                         if (tcp_metrics_dump_info(skb, cb, tm) < 0) {
 769                                 rcu_read_unlock();
 770                                 goto done;
 771                         }
 772                 }
 773                 rcu_read_unlock();
 774         }
 775
 776 done:
 777         cb->args[0] = row;
 778         cb->args[1] = col;
 779         return skb->len;
 780 }
 781
 782 static int __parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 783                            unsigned int *hash, int optional, int v4, int v6)
 784 {
 785         struct nlattr *a;
 786
 787         a = info->attrs[v4];
 788         if (a) {
 789                 inetpeer_set_addr_v4(addr, nla_get_in_addr(a));
 790                 if (hash)
 791                         *hash = ipv4_addr_hash(inetpeer_get_addr_v4(addr));
 792                 return 0;
 793         }
 794         a = info->attrs[v6];
 795         if (a) {
 796                 struct in6_addr in6;
 797
 798                 if (nla_len(a) != sizeof(struct in6_addr))
 799                         return -EINVAL;
 800                 in6 = nla_get_in6_addr(a);
 801                 inetpeer_set_addr_v6(addr, &in6);
 802                 if (hash)
 803                         *hash = ipv6_addr_hash(inetpeer_get_addr_v6(addr));
 804                 return 0;
 805         }
 806         return optional ? 1 : -EAFNOSUPPORT;
 807 }
 808
 809 static int parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 810                          unsigned int *hash, int optional)
 811 {
 812         return __parse_nl_addr(info, addr, hash, optional,
 813                                TCP_METRICS_ATTR_ADDR_IPV4,
 814                                TCP_METRICS_ATTR_ADDR_IPV6);
 815 }
 816
 817 static int parse_nl_saddr(struct genl_info *info, struct inetpeer_addr *addr)
 818 {
 819         return __parse_nl_addr(info, addr, NULL, 0,
 820                                TCP_METRICS_ATTR_SADDR_IPV4,
 821                                TCP_METRICS_ATTR_SADDR_IPV6);
 822 }
 823
 824 static int tcp_metrics_nl_cmd_get(struct sk_buff *skb, struct genl_info *info)
 825 {
 826         struct tcp_metrics_block *tm;
 827         struct inetpeer_addr saddr, daddr;
 828         unsigned int hash;
 829         struct sk_buff *msg;
 830         struct net *net = genl_info_net(info);
 831         void *reply;
 832         int ret;
 833         bool src = true;
 834
 835         ret = parse_nl_addr(info, &daddr, &hash, 0);
 836         if (ret < 0)
 837                 return ret;
 838
 839         ret = parse_nl_saddr(info, &saddr);
 840         if (ret < 0)
 841                 src = false;
 842
 843         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 844         if (!msg)
 845                 return -ENOMEM;
 846
 847         reply = genlmsg_put_reply(msg, info, &tcp_metrics_nl_family, 0,
 848                                   info->genlhdr->cmd);
 849         if (!reply)
 850                 goto nla_put_failure;
 851
 852         hash ^= net_hash_mix(net);
 853         hash = hash_32(hash, tcp_metrics_hash_log);
 854         ret = -ESRCH;
 855         rcu_read_lock();
 856         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
 857              tm = rcu_dereference(tm->tcpm_next)) {
 858                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
 859                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
 860                     net_eq(tm_net(tm), net)) {
 861                         ret = tcp_metrics_fill_info(msg, tm);
 862                         break;
 863                 }
 864         }
 865         rcu_read_unlock();
 866         if (ret < 0)
 867                 goto out_free;
 868
 869         genlmsg_end(msg, reply);
 870         return genlmsg_reply(msg, info);
 871
 872 nla_put_failure:
 873         ret = -EMSGSIZE;
 874
 875 out_free:
 876         nlmsg_free(msg);
 877         return ret;
 878 }
 879
 880 static void tcp_metrics_flush_all(struct net *net)
 881 {
 882         unsigned int max_rows = 1U << tcp_metrics_hash_log;
 883         struct tcpm_hash_bucket *hb = tcp_metrics_hash;
 884         struct tcp_metrics_block *tm;
 885         unsigned int row;
 886
 887         for (row = 0; row < max_rows; row++, hb++) {
 888                 struct tcp_metrics_block __rcu **pp;
 889                 bool match;
 890
 891                 spin_lock_bh(&tcp_metrics_lock);
 892                 pp = &hb->chain;
 893                 for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
 894                         match = net ? net_eq(tm_net(tm), net) :
 895                                 !refcount_read(&tm_net(tm)->count);
 896                         if (match) {
 897                                 *pp = tm->tcpm_next;
 898                                 kfree_rcu(tm, rcu_head);
 899                         } else {
 900                                 pp = &tm->tcpm_next;
 901                         }
 902                 }
 903                 spin_unlock_bh(&tcp_metrics_lock);
 904         }
 905 }
 906
 907 static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info)
 908 {
 909         struct tcpm_hash_bucket *hb;
 910         struct tcp_metrics_block *tm;
 911         struct tcp_metrics_block __rcu **pp;
 912         struct inetpeer_addr saddr, daddr;
 913         unsigned int hash;
 914         struct net *net = genl_info_net(info);
 915         int ret;
 916         bool src = true, found = false;
 917
 918         ret = parse_nl_addr(info, &daddr, &hash, 1);
 919         if (ret < 0)
 920                 return ret;
 921         if (ret > 0) {
 922                 tcp_metrics_flush_all(net);
 923                 return 0;
 924         }
 925         ret = parse_nl_saddr(info, &saddr);
 926         if (ret < 0)
 927                 src = false;
 928
 929         hash ^= net_hash_mix(net);
 930         hash = hash_32(hash, tcp_metrics_hash_log);
 931         hb = tcp_metrics_hash + hash;
 932         pp = &hb->chain;
 933         spin_lock_bh(&tcp_metrics_lock);
 934         for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
 935                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
 936                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
 937                     net_eq(tm_net(tm), net)) {
 938                         *pp = tm->tcpm_next;
 939                         kfree_rcu(tm, rcu_head);
 940                         found = true;
 941                 } else {
 942                         pp = &tm->tcpm_next;
 943                 }
 944         }
 945         spin_unlock_bh(&tcp_metrics_lock);
 946         if (!found)
 947                 return -ESRCH;
 948         return 0;
 949 }
 950
 951 static const struct genl_ops tcp_metrics_nl_ops[] = {
 952         {
 953                 .cmd = TCP_METRICS_CMD_GET,
 954                 .doit = tcp_metrics_nl_cmd_get,
 955                 .dumpit = tcp_metrics_nl_dump,
 956                 .policy = tcp_metrics_nl_policy,
 957         },
 958         {
 959                 .cmd = TCP_METRICS_CMD_DEL,
 960                 .doit = tcp_metrics_nl_cmd_del,
 961                 .policy = tcp_metrics_nl_policy,
 962                 .flags = GENL_ADMIN_PERM,
 963         },
 964 };
 965
 966 static struct genl_family tcp_metrics_nl_family __ro_after_init = {
 967         .hdrsize        = 0,
 968         .name           = TCP_METRICS_GENL_NAME,
 969         .version        = TCP_METRICS_GENL_VERSION,
 970         .maxattr        = TCP_METRICS_ATTR_MAX,
 971         .netnsok        = true,
 972         .module         = THIS_MODULE,
 973         .ops            = tcp_metrics_nl_ops,
 974         .n_ops          = ARRAY_SIZE(tcp_metrics_nl_ops),
 975 };
 976
 977 static unsigned int tcpmhash_entries;
 978 static int __init set_tcpmhash_entries(char *str)
 979 {
 980         ssize_t ret;
 981
 982         if (!str)
 983                 return 0;
 984
 985         ret = kstrtouint(str, 0, &tcpmhash_entries);
 986         if (ret)
 987                 return 0;
 988
 989         return 1;
 990 }
 991 __setup("tcpmhash_entries=", set_tcpmhash_entries);
 992
 993 static int __net_init tcp_net_metrics_init(struct net *net)
 994 {
 995         size_t size;
 996         unsigned int slots;
 997
 998         if (!net_eq(net, &init_net))
 999                 return 0;
1000
1001         slots = tcpmhash_entries;
1002         if (!slots) {
1003                 if (totalram_pages >= 128 * 1024)
1004                         slots = 16 * 1024;
1005                 else
1006                         slots = 8 * 1024;
1007         }
1008
1009         tcp_metrics_hash_log = order_base_2(slots);
1010         size = sizeof(struct tcpm_hash_bucket) << tcp_metrics_hash_log;
1011
1012         tcp_metrics_hash = kvzalloc(size, GFP_KERNEL);
1013         if (!tcp_metrics_hash)
1014                 return -ENOMEM;
1015
1016         return 0;
1017 }
1018
1019 static void __net_exit tcp_net_metrics_exit_batch(struct list_head *net_exit_list)
1020 {
1021         tcp_metrics_flush_all(NULL);
1022 }
1023
1024 static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
1025         .init           =       tcp_net_metrics_init,
1026         .exit_batch     =       tcp_net_metrics_exit_batch,
1027 };
1028
1029 void __init tcp_metrics_init(void)
1030 {
1031         int ret;
1032
1033         ret = register_pernet_subsys(&tcp_net_metrics_ops);
1034         if (ret < 0)
1035                 panic("Could not allocate the tcp_metrics hash table\n");
1036
1037         ret = genl_register_family(&tcp_metrics_nl_family);
1038         if (ret < 0)
1039                 panic("Could not register tcp_metrics generic netlink\n");
1040 }