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 (!net->ipv4.sysctl_tcp_no_ssthresh_metrics_save &&
 389                     !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 (!net->ipv4.sysctl_tcp_no_ssthresh_metrics_save &&
 405                     !tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
 406                         tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 407                                        max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
 408                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 409                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 410                         tcp_metric_set(tm, TCP_METRIC_CWND, (val + tp->snd_cwnd) >> 1);
 411                 }
 412         } else {
 413                 /* Else slow start did not finish, cwnd is non-sense,
 414                  * ssthresh may be also invalid.
 415                  */
 416                 if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
 417                         val = tcp_metric_get(tm, TCP_METRIC_CWND);
 418                         tcp_metric_set(tm, TCP_METRIC_CWND,
 419                                        (val + tp->snd_ssthresh) >> 1);
 420                 }
 421                 if (!net->ipv4.sysctl_tcp_no_ssthresh_metrics_save &&
 422                     !tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
 423                         val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 424                         if (val && tp->snd_ssthresh > val)
 425                                 tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
 426                                                tp->snd_ssthresh);
 427                 }
 428                 if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {
 429                         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 430                         if (val < tp->reordering &&
 431                             tp->reordering != net->ipv4.sysctl_tcp_reordering)
 432                                 tcp_metric_set(tm, TCP_METRIC_REORDERING,
 433                                                tp->reordering);
 434                 }
 435         }
 436         tm->tcpm_stamp = jiffies;
 437 out_unlock:
 438         rcu_read_unlock();
 439 }
 440
 441 /* Initialize metrics on socket. */
 442
 443 void tcp_init_metrics(struct sock *sk)
 444 {
 445         struct dst_entry *dst = __sk_dst_get(sk);
 446         struct tcp_sock *tp = tcp_sk(sk);
 447         struct net *net = sock_net(sk);
 448         struct tcp_metrics_block *tm;
 449         u32 val, crtt = 0; /* cached RTT scaled by 8 */
 450
 451         sk_dst_confirm(sk);
 452         if (!dst)
 453                 goto reset;
 454
 455         rcu_read_lock();
 456         tm = tcp_get_metrics(sk, dst, true);
 457         if (!tm) {
 458                 rcu_read_unlock();
 459                 goto reset;
 460         }
 461
 462         if (tcp_metric_locked(tm, TCP_METRIC_CWND))
 463                 tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
 464
 465         val = net->ipv4.sysctl_tcp_no_ssthresh_metrics_save ?
 466               0 : tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
 467         if (val) {
 468                 tp->snd_ssthresh = val;
 469                 if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
 470                         tp->snd_ssthresh = tp->snd_cwnd_clamp;
 471         } else {
 472                 /* ssthresh may have been reduced unnecessarily during.
 473                  * 3WHS. Restore it back to its initial default.
 474                  */
 475                 tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
 476         }
 477         val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
 478         if (val && tp->reordering != val)
 479                 tp->reordering = val;
 480
 481         crtt = tcp_metric_get(tm, TCP_METRIC_RTT);
 482         rcu_read_unlock();
 483 reset:
 484         /* The initial RTT measurement from the SYN/SYN-ACK is not ideal
 485          * to seed the RTO for later data packets because SYN packets are
 486          * small. Use the per-dst cached values to seed the RTO but keep
 487          * the RTT estimator variables intact (e.g., srtt, mdev, rttvar).
 488          * Later the RTO will be updated immediately upon obtaining the first
 489          * data RTT sample (tcp_rtt_estimator()). Hence the cached RTT only
 490          * influences the first RTO but not later RTT estimation.
 491          *
 492          * But if RTT is not available from the SYN (due to retransmits or
 493          * syn cookies) or the cache, force a conservative 3secs timeout.
 494          *
 495          * A bit of theory. RTT is time passed after "normal" sized packet
 496          * is sent until it is ACKed. In normal circumstances sending small
 497          * packets force peer to delay ACKs and calculation is correct too.
 498          * The algorithm is adaptive and, provided we follow specs, it
 499          * NEVER underestimate RTT. BUT! If peer tries to make some clever
 500          * tricks sort of "quick acks" for time long enough to decrease RTT
 501          * to low value, and then abruptly stops to do it and starts to delay
 502          * ACKs, wait for troubles.
 503          */
 504         if (crtt > tp->srtt_us) {
 505                 /* Set RTO like tcp_rtt_estimator(), but from cached RTT. */
 506                 crtt /= 8 * USEC_PER_SEC / HZ;
 507                 inet_csk(sk)->icsk_rto = crtt + max(2 * crtt, tcp_rto_min(sk));
 508         } else if (tp->srtt_us == 0) {
 509                 /* RFC6298: 5.7 We've failed to get a valid RTT sample from
 510                  * 3WHS. This is most likely due to retransmission,
 511                  * including spurious one. Reset the RTO back to 3secs
 512                  * from the more aggressive 1sec to avoid more spurious
 513                  * retransmission.
 514                  */
 515                 tp->rttvar_us = jiffies_to_usecs(TCP_TIMEOUT_FALLBACK);
 516                 tp->mdev_us = tp->mdev_max_us = tp->rttvar_us;
 517
 518                 inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
 519         }
 520 }
 521
 522 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst)
 523 {
 524         struct tcp_metrics_block *tm;
 525         bool ret;
 526
 527         if (!dst)
 528                 return false;
 529
 530         rcu_read_lock();
 531         tm = __tcp_get_metrics_req(req, dst);
 532         if (tm && tcp_metric_get(tm, TCP_METRIC_RTT))
 533                 ret = true;
 534         else
 535                 ret = false;
 536         rcu_read_unlock();
 537
 538         return ret;
 539 }
 540
 541 static DEFINE_SEQLOCK(fastopen_seqlock);
 542
 543 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
 544                             struct tcp_fastopen_cookie *cookie)
 545 {
 546         struct tcp_metrics_block *tm;
 547
 548         rcu_read_lock();
 549         tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
 550         if (tm) {
 551                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 552                 unsigned int seq;
 553
 554                 do {
 555                         seq = read_seqbegin(&fastopen_seqlock);
 556                         if (tfom->mss)
 557                                 *mss = tfom->mss;
 558                         *cookie = tfom->cookie;
 559                         if (cookie->len <= 0 && tfom->try_exp == 1)
 560                                 cookie->exp = true;
 561                 } while (read_seqretry(&fastopen_seqlock, seq));
 562         }
 563         rcu_read_unlock();
 564 }
 565
 566 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
 567                             struct tcp_fastopen_cookie *cookie, bool syn_lost,
 568                             u16 try_exp)
 569 {
 570         struct dst_entry *dst = __sk_dst_get(sk);
 571         struct tcp_metrics_block *tm;
 572
 573         if (!dst)
 574                 return;
 575         rcu_read_lock();
 576         tm = tcp_get_metrics(sk, dst, true);
 577         if (tm) {
 578                 struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
 579
 580                 write_seqlock_bh(&fastopen_seqlock);
 581                 if (mss)
 582                         tfom->mss = mss;
 583                 if (cookie && cookie->len > 0)
 584                         tfom->cookie = *cookie;
 585                 else if (try_exp > tfom->try_exp &&
 586                          tfom->cookie.len <= 0 && !tfom->cookie.exp)
 587                         tfom->try_exp = try_exp;
 588                 if (syn_lost) {
 589                         ++tfom->syn_loss;
 590                         tfom->last_syn_loss = jiffies;
 591                 } else
 592                         tfom->syn_loss = 0;
 593                 write_sequnlock_bh(&fastopen_seqlock);
 594         }
 595         rcu_read_unlock();
 596 }
 597
 598 static struct genl_family tcp_metrics_nl_family;
 599
 600 static const struct nla_policy tcp_metrics_nl_policy[TCP_METRICS_ATTR_MAX + 1] = {
 601         [TCP_METRICS_ATTR_ADDR_IPV4]    = { .type = NLA_U32, },
 602         [TCP_METRICS_ATTR_ADDR_IPV6]    = { .type = NLA_BINARY,
 603                                             .len = sizeof(struct in6_addr), },
 604         /* Following attributes are not received for GET/DEL,
 605          * we keep them for reference
 606          */
 607 #if 0
 608         [TCP_METRICS_ATTR_AGE]          = { .type = NLA_MSECS, },
 609         [TCP_METRICS_ATTR_TW_TSVAL]     = { .type = NLA_U32, },
 610         [TCP_METRICS_ATTR_TW_TS_STAMP]  = { .type = NLA_S32, },
 611         [TCP_METRICS_ATTR_VALS]         = { .type = NLA_NESTED, },
 612         [TCP_METRICS_ATTR_FOPEN_MSS]    = { .type = NLA_U16, },
 613         [TCP_METRICS_ATTR_FOPEN_SYN_DROPS]      = { .type = NLA_U16, },
 614         [TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS]    = { .type = NLA_MSECS, },
 615         [TCP_METRICS_ATTR_FOPEN_COOKIE] = { .type = NLA_BINARY,
 616                                             .len = TCP_FASTOPEN_COOKIE_MAX, },
 617 #endif
 618 };
 619
 620 /* Add attributes, caller cancels its header on failure */
 621 static int tcp_metrics_fill_info(struct sk_buff *msg,
 622                                  struct tcp_metrics_block *tm)
 623 {
 624         struct nlattr *nest;
 625         int i;
 626
 627         switch (tm->tcpm_daddr.family) {
 628         case AF_INET:
 629                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_ADDR_IPV4,
 630                                     inetpeer_get_addr_v4(&tm->tcpm_daddr)) < 0)
 631                         goto nla_put_failure;
 632                 if (nla_put_in_addr(msg, TCP_METRICS_ATTR_SADDR_IPV4,
 633                                     inetpeer_get_addr_v4(&tm->tcpm_saddr)) < 0)
 634                         goto nla_put_failure;
 635                 break;
 636         case AF_INET6:
 637                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_ADDR_IPV6,
 638                                      inetpeer_get_addr_v6(&tm->tcpm_daddr)) < 0)
 639                         goto nla_put_failure;
 640                 if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_SADDR_IPV6,
 641                                      inetpeer_get_addr_v6(&tm->tcpm_saddr)) < 0)
 642                         goto nla_put_failure;
 643                 break;
 644         default:
 645                 return -EAFNOSUPPORT;
 646         }
 647
 648         if (nla_put_msecs(msg, TCP_METRICS_ATTR_AGE,
 649                           jiffies - tm->tcpm_stamp,
 650                           TCP_METRICS_ATTR_PAD) < 0)
 651                 goto nla_put_failure;
 652
 653         {
 654                 int n = 0;
 655
 656                 nest = nla_nest_start_noflag(msg, TCP_METRICS_ATTR_VALS);
 657                 if (!nest)
 658                         goto nla_put_failure;
 659                 for (i = 0; i < TCP_METRIC_MAX_KERNEL + 1; i++) {
 660                         u32 val = tm->tcpm_vals[i];
 661
 662                         if (!val)
 663                                 continue;
 664                         if (i == TCP_METRIC_RTT) {
 665                                 if (nla_put_u32(msg, TCP_METRIC_RTT_US + 1,
 666                                                 val) < 0)
 667                                         goto nla_put_failure;
 668                                 n++;
 669                                 val = max(val / 1000, 1U);
 670                         }
 671                         if (i == TCP_METRIC_RTTVAR) {
 672                                 if (nla_put_u32(msg, TCP_METRIC_RTTVAR_US + 1,
 673                                                 val) < 0)
 674                                         goto nla_put_failure;
 675                                 n++;
 676                                 val = max(val / 1000, 1U);
 677                         }
 678                         if (nla_put_u32(msg, i + 1, val) < 0)
 679                                 goto nla_put_failure;
 680                         n++;
 681                 }
 682                 if (n)
 683                         nla_nest_end(msg, nest);
 684                 else
 685                         nla_nest_cancel(msg, nest);
 686         }
 687
 688         {
 689                 struct tcp_fastopen_metrics tfom_copy[1], *tfom;
 690                 unsigned int seq;
 691
 692                 do {
 693                         seq = read_seqbegin(&fastopen_seqlock);
 694                         tfom_copy[0] = tm->tcpm_fastopen;
 695                 } while (read_seqretry(&fastopen_seqlock, seq));
 696
 697                 tfom = tfom_copy;
 698                 if (tfom->mss &&
 699                     nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_MSS,
 700                                 tfom->mss) < 0)
 701                         goto nla_put_failure;
 702                 if (tfom->syn_loss &&
 703                     (nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROPS,
 704                                 tfom->syn_loss) < 0 ||
 705                      nla_put_msecs(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS,
 706                                 jiffies - tfom->last_syn_loss,
 707                                 TCP_METRICS_ATTR_PAD) < 0))
 708                         goto nla_put_failure;
 709                 if (tfom->cookie.len > 0 &&
 710                     nla_put(msg, TCP_METRICS_ATTR_FOPEN_COOKIE,
 711                             tfom->cookie.len, tfom->cookie.val) < 0)
 712                         goto nla_put_failure;
 713         }
 714
 715         return 0;
 716
 717 nla_put_failure:
 718         return -EMSGSIZE;
 719 }
 720
 721 static int tcp_metrics_dump_info(struct sk_buff *skb,
 722                                  struct netlink_callback *cb,
 723                                  struct tcp_metrics_block *tm)
 724 {
 725         void *hdr;
 726
 727         hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
 728                           &tcp_metrics_nl_family, NLM_F_MULTI,
 729                           TCP_METRICS_CMD_GET);
 730         if (!hdr)
 731                 return -EMSGSIZE;
 732
 733         if (tcp_metrics_fill_info(skb, tm) < 0)
 734                 goto nla_put_failure;
 735
 736         genlmsg_end(skb, hdr);
 737         return 0;
 738
 739 nla_put_failure:
 740         genlmsg_cancel(skb, hdr);
 741         return -EMSGSIZE;
 742 }
 743
 744 static int tcp_metrics_nl_dump(struct sk_buff *skb,
 745                                struct netlink_callback *cb)
 746 {
 747         struct net *net = sock_net(skb->sk);
 748         unsigned int max_rows = 1U << tcp_metrics_hash_log;
 749         unsigned int row, s_row = cb->args[0];
 750         int s_col = cb->args[1], col = s_col;
 751
 752         for (row = s_row; row < max_rows; row++, s_col = 0) {
 753                 struct tcp_metrics_block *tm;
 754                 struct tcpm_hash_bucket *hb = tcp_metrics_hash + row;
 755
 756                 rcu_read_lock();
 757                 for (col = 0, tm = rcu_dereference(hb->chain); tm;
 758                      tm = rcu_dereference(tm->tcpm_next), col++) {
 759                         if (!net_eq(tm_net(tm), net))
 760                                 continue;
 761                         if (col < s_col)
 762                                 continue;
 763                         if (tcp_metrics_dump_info(skb, cb, tm) < 0) {
 764                                 rcu_read_unlock();
 765                                 goto done;
 766                         }
 767                 }
 768                 rcu_read_unlock();
 769         }
 770
 771 done:
 772         cb->args[0] = row;
 773         cb->args[1] = col;
 774         return skb->len;
 775 }
 776
 777 static int __parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 778                            unsigned int *hash, int optional, int v4, int v6)
 779 {
 780         struct nlattr *a;
 781
 782         a = info->attrs[v4];
 783         if (a) {
 784                 inetpeer_set_addr_v4(addr, nla_get_in_addr(a));
 785                 if (hash)
 786                         *hash = ipv4_addr_hash(inetpeer_get_addr_v4(addr));
 787                 return 0;
 788         }
 789         a = info->attrs[v6];
 790         if (a) {
 791                 struct in6_addr in6;
 792
 793                 if (nla_len(a) != sizeof(struct in6_addr))
 794                         return -EINVAL;
 795                 in6 = nla_get_in6_addr(a);
 796                 inetpeer_set_addr_v6(addr, &in6);
 797                 if (hash)
 798                         *hash = ipv6_addr_hash(inetpeer_get_addr_v6(addr));
 799                 return 0;
 800         }
 801         return optional ? 1 : -EAFNOSUPPORT;
 802 }
 803
 804 static int parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
 805                          unsigned int *hash, int optional)
 806 {
 807         return __parse_nl_addr(info, addr, hash, optional,
 808                                TCP_METRICS_ATTR_ADDR_IPV4,
 809                                TCP_METRICS_ATTR_ADDR_IPV6);
 810 }
 811
 812 static int parse_nl_saddr(struct genl_info *info, struct inetpeer_addr *addr)
 813 {
 814         return __parse_nl_addr(info, addr, NULL, 0,
 815                                TCP_METRICS_ATTR_SADDR_IPV4,
 816                                TCP_METRICS_ATTR_SADDR_IPV6);
 817 }
 818
 819 static int tcp_metrics_nl_cmd_get(struct sk_buff *skb, struct genl_info *info)
 820 {
 821         struct tcp_metrics_block *tm;
 822         struct inetpeer_addr saddr, daddr;
 823         unsigned int hash;
 824         struct sk_buff *msg;
 825         struct net *net = genl_info_net(info);
 826         void *reply;
 827         int ret;
 828         bool src = true;
 829
 830         ret = parse_nl_addr(info, &daddr, &hash, 0);
 831         if (ret < 0)
 832                 return ret;
 833
 834         ret = parse_nl_saddr(info, &saddr);
 835         if (ret < 0)
 836                 src = false;
 837
 838         msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 839         if (!msg)
 840                 return -ENOMEM;
 841
 842         reply = genlmsg_put_reply(msg, info, &tcp_metrics_nl_family, 0,
 843                                   info->genlhdr->cmd);
 844         if (!reply)
 845                 goto nla_put_failure;
 846
 847         hash ^= net_hash_mix(net);
 848         hash = hash_32(hash, tcp_metrics_hash_log);
 849         ret = -ESRCH;
 850         rcu_read_lock();
 851         for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
 852              tm = rcu_dereference(tm->tcpm_next)) {
 853                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
 854                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
 855                     net_eq(tm_net(tm), net)) {
 856                         ret = tcp_metrics_fill_info(msg, tm);
 857                         break;
 858                 }
 859         }
 860         rcu_read_unlock();
 861         if (ret < 0)
 862                 goto out_free;
 863
 864         genlmsg_end(msg, reply);
 865         return genlmsg_reply(msg, info);
 866
 867 nla_put_failure:
 868         ret = -EMSGSIZE;
 869
 870 out_free:
 871         nlmsg_free(msg);
 872         return ret;
 873 }
 874
 875 static void tcp_metrics_flush_all(struct net *net)
 876 {
 877         unsigned int max_rows = 1U << tcp_metrics_hash_log;
 878         struct tcpm_hash_bucket *hb = tcp_metrics_hash;
 879         struct tcp_metrics_block *tm;
 880         unsigned int row;
 881
 882         for (row = 0; row < max_rows; row++, hb++) {
 883                 struct tcp_metrics_block __rcu **pp;
 884                 bool match;
 885
 886                 spin_lock_bh(&tcp_metrics_lock);
 887                 pp = &hb->chain;
 888                 for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
 889                         match = net ? net_eq(tm_net(tm), net) :
 890                                 !refcount_read(&tm_net(tm)->count);
 891                         if (match) {
 892                                 *pp = tm->tcpm_next;
 893                                 kfree_rcu(tm, rcu_head);
 894                         } else {
 895                                 pp = &tm->tcpm_next;
 896                         }
 897                 }
 898                 spin_unlock_bh(&tcp_metrics_lock);
 899         }
 900 }
 901
 902 static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info)
 903 {
 904         struct tcpm_hash_bucket *hb;
 905         struct tcp_metrics_block *tm;
 906         struct tcp_metrics_block __rcu **pp;
 907         struct inetpeer_addr saddr, daddr;
 908         unsigned int hash;
 909         struct net *net = genl_info_net(info);
 910         int ret;
 911         bool src = true, found = false;
 912
 913         ret = parse_nl_addr(info, &daddr, &hash, 1);
 914         if (ret < 0)
 915                 return ret;
 916         if (ret > 0) {
 917                 tcp_metrics_flush_all(net);
 918                 return 0;
 919         }
 920         ret = parse_nl_saddr(info, &saddr);
 921         if (ret < 0)
 922                 src = false;
 923
 924         hash ^= net_hash_mix(net);
 925         hash = hash_32(hash, tcp_metrics_hash_log);
 926         hb = tcp_metrics_hash + hash;
 927         pp = &hb->chain;
 928         spin_lock_bh(&tcp_metrics_lock);
 929         for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
 930                 if (addr_same(&tm->tcpm_daddr, &daddr) &&
 931                     (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
 932                     net_eq(tm_net(tm), net)) {
 933                         *pp = tm->tcpm_next;
 934                         kfree_rcu(tm, rcu_head);
 935                         found = true;
 936                 } else {
 937                         pp = &tm->tcpm_next;
 938                 }
 939         }
 940         spin_unlock_bh(&tcp_metrics_lock);
 941         if (!found)
 942                 return -ESRCH;
 943         return 0;
 944 }
 945
 946 static const struct genl_ops tcp_metrics_nl_ops[] = {
 947         {
 948                 .cmd = TCP_METRICS_CMD_GET,
 949                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 950                 .doit = tcp_metrics_nl_cmd_get,
 951                 .dumpit = tcp_metrics_nl_dump,
 952         },
 953         {
 954                 .cmd = TCP_METRICS_CMD_DEL,
 955                 .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
 956                 .doit = tcp_metrics_nl_cmd_del,
 957                 .flags = GENL_ADMIN_PERM,
 958         },
 959 };
 960
 961 static struct genl_family tcp_metrics_nl_family __ro_after_init = {
 962         .hdrsize        = 0,
 963         .name           = TCP_METRICS_GENL_NAME,
 964         .version        = TCP_METRICS_GENL_VERSION,
 965         .maxattr        = TCP_METRICS_ATTR_MAX,
 966         .policy = tcp_metrics_nl_policy,
 967         .netnsok        = true,
 968         .module         = THIS_MODULE,
 969         .ops            = tcp_metrics_nl_ops,
 970         .n_ops          = ARRAY_SIZE(tcp_metrics_nl_ops),
 971 };
 972
 973 static unsigned int tcpmhash_entries;
 974 static int __init set_tcpmhash_entries(char *str)
 975 {
 976         ssize_t ret;
 977
 978         if (!str)
 979                 return 0;
 980
 981         ret = kstrtouint(str, 0, &tcpmhash_entries);
 982         if (ret)
 983                 return 0;
 984
 985         return 1;
 986 }
 987 __setup("tcpmhash_entries=", set_tcpmhash_entries);
 988
 989 static int __net_init tcp_net_metrics_init(struct net *net)
 990 {
 991         size_t size;
 992         unsigned int slots;
 993
 994         if (!net_eq(net, &init_net))
 995                 return 0;
 996
 997         slots = tcpmhash_entries;
 998         if (!slots) {
 999                 if (totalram_pages() >= 128 * 1024)
1000                         slots = 16 * 1024;
1001                 else
1002                         slots = 8 * 1024;
1003         }
1004
1005         tcp_metrics_hash_log = order_base_2(slots);
1006         size = sizeof(struct tcpm_hash_bucket) << tcp_metrics_hash_log;
1007
1008         tcp_metrics_hash = kvzalloc(size, GFP_KERNEL);
1009         if (!tcp_metrics_hash)
1010                 return -ENOMEM;
1011
1012         return 0;
1013 }
1014
1015 static void __net_exit tcp_net_metrics_exit_batch(struct list_head *net_exit_list)
1016 {
1017         tcp_metrics_flush_all(NULL);
1018 }
1019
1020 static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
1021         .init           =       tcp_net_metrics_init,
1022         .exit_batch     =       tcp_net_metrics_exit_batch,
1023 };
1024
1025 void __init tcp_metrics_init(void)
1026 {
1027         int ret;
1028
1029         ret = register_pernet_subsys(&tcp_net_metrics_ops);
1030         if (ret < 0)
1031                 panic("Could not allocate the tcp_metrics hash table\n");
1032
1033         ret = genl_register_family(&tcp_metrics_nl_family);
1034         if (ret < 0)
1035                 panic("Could not register tcp_metrics generic netlink\n");
1036 }