1 files changed, 1054 insertions, 0 deletions

diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c
new file mode 100644
index 000000000..f823a15b9
--- /dev/null
+++ b/net/ipv4/tcp_metrics.c
@@ -0,0 +1,1054 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/rcupdate.h>
+#include <linux/spinlock.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/cache.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/tcp.h>
+#include <linux/hash.h>
+#include <linux/tcp_metrics.h>
+#include <linux/vmalloc.h>
+
+#include <net/inet_connection_sock.h>
+#include <net/net_namespace.h>
+#include <net/request_sock.h>
+#include <net/inetpeer.h>
+#include <net/sock.h>
+#include <net/ipv6.h>
+#include <net/dst.h>
+#include <net/tcp.h>
+#include <net/genetlink.h>
+
+static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
+						   const struct inetpeer_addr *daddr,
+						   struct net *net, unsigned int hash);
+
+struct tcp_fastopen_metrics {
+	u16	mss;
+	u16	syn_loss:10,		/* Recurring Fast Open SYN losses */
+		try_exp:2;		/* Request w/ exp. option (once) */
+	unsigned long	last_syn_loss;	/* Last Fast Open SYN loss */
+	struct	tcp_fastopen_cookie	cookie;
+};
+
+/* TCP_METRIC_MAX includes 2 extra fields for userspace compatibility
+ * Kernel only stores RTT and RTTVAR in usec resolution
+ */
+#define TCP_METRIC_MAX_KERNEL (TCP_METRIC_MAX - 2)
+
+struct tcp_metrics_block {
+	struct tcp_metrics_block __rcu	*tcpm_next;
+	struct net			*tcpm_net;
+	struct inetpeer_addr		tcpm_saddr;
+	struct inetpeer_addr		tcpm_daddr;
+	unsigned long			tcpm_stamp;
+	u32				tcpm_lock;
+	u32				tcpm_vals[TCP_METRIC_MAX_KERNEL + 1];
+	struct tcp_fastopen_metrics	tcpm_fastopen;
+
+	struct rcu_head			rcu_head;
+};
+
+static inline struct net *tm_net(const struct tcp_metrics_block *tm)
+{
+	/* Paired with the WRITE_ONCE() in tcpm_new() */
+	return READ_ONCE(tm->tcpm_net);
+}
+
+static bool tcp_metric_locked(struct tcp_metrics_block *tm,
+			      enum tcp_metric_index idx)
+{
+	/* Paired with WRITE_ONCE() in tcpm_suck_dst() */
+	return READ_ONCE(tm->tcpm_lock) & (1 << idx);
+}
+
+static u32 tcp_metric_get(const struct tcp_metrics_block *tm,
+			  enum tcp_metric_index idx)
+{
+	/* Paired with WRITE_ONCE() in tcp_metric_set() */
+	return READ_ONCE(tm->tcpm_vals[idx]);
+}
+
+static void tcp_metric_set(struct tcp_metrics_block *tm,
+			   enum tcp_metric_index idx,
+			   u32 val)
+{
+	/* Paired with READ_ONCE() in tcp_metric_get() */
+	WRITE_ONCE(tm->tcpm_vals[idx], val);
+}
+
+static bool addr_same(const struct inetpeer_addr *a,
+		      const struct inetpeer_addr *b)
+{
+	return (a->family == b->family) && !inetpeer_addr_cmp(a, b);
+}
+
+struct tcpm_hash_bucket {
+	struct tcp_metrics_block __rcu	*chain;
+};
+
+static struct tcpm_hash_bucket	*tcp_metrics_hash __read_mostly;
+static unsigned int		tcp_metrics_hash_log __read_mostly;
+
+static DEFINE_SPINLOCK(tcp_metrics_lock);
+static DEFINE_SEQLOCK(fastopen_seqlock);
+
+static void tcpm_suck_dst(struct tcp_metrics_block *tm,
+			  const struct dst_entry *dst,
+			  bool fastopen_clear)
+{
+	u32 msval;
+	u32 val;
+
+	WRITE_ONCE(tm->tcpm_stamp, jiffies);
+
+	val = 0;
+	if (dst_metric_locked(dst, RTAX_RTT))
+		val |= 1 << TCP_METRIC_RTT;
+	if (dst_metric_locked(dst, RTAX_RTTVAR))
+		val |= 1 << TCP_METRIC_RTTVAR;
+	if (dst_metric_locked(dst, RTAX_SSTHRESH))
+		val |= 1 << TCP_METRIC_SSTHRESH;
+	if (dst_metric_locked(dst, RTAX_CWND))
+		val |= 1 << TCP_METRIC_CWND;
+	if (dst_metric_locked(dst, RTAX_REORDERING))
+		val |= 1 << TCP_METRIC_REORDERING;
+	/* Paired with READ_ONCE() in tcp_metric_locked() */
+	WRITE_ONCE(tm->tcpm_lock, val);
+
+	msval = dst_metric_raw(dst, RTAX_RTT);
+	tcp_metric_set(tm, TCP_METRIC_RTT, msval * USEC_PER_MSEC);
+
+	msval = dst_metric_raw(dst, RTAX_RTTVAR);
+	tcp_metric_set(tm, TCP_METRIC_RTTVAR, msval * USEC_PER_MSEC);
+	tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
+		       dst_metric_raw(dst, RTAX_SSTHRESH));
+	tcp_metric_set(tm, TCP_METRIC_CWND,
+		       dst_metric_raw(dst, RTAX_CWND));
+	tcp_metric_set(tm, TCP_METRIC_REORDERING,
+		       dst_metric_raw(dst, RTAX_REORDERING));
+	if (fastopen_clear) {
+		write_seqlock(&fastopen_seqlock);
+		tm->tcpm_fastopen.mss = 0;
+		tm->tcpm_fastopen.syn_loss = 0;
+		tm->tcpm_fastopen.try_exp = 0;
+		tm->tcpm_fastopen.cookie.exp = false;
+		tm->tcpm_fastopen.cookie.len = 0;
+		write_sequnlock(&fastopen_seqlock);
+	}
+}
+
+#define TCP_METRICS_TIMEOUT		(60 * 60 * HZ)
+
+static void tcpm_check_stamp(struct tcp_metrics_block *tm,
+			     const struct dst_entry *dst)
+{
+	unsigned long limit;
+
+	if (!tm)
+		return;
+	limit = READ_ONCE(tm->tcpm_stamp) + TCP_METRICS_TIMEOUT;
+	if (unlikely(time_after(jiffies, limit)))
+		tcpm_suck_dst(tm, dst, false);
+}
+
+#define TCP_METRICS_RECLAIM_DEPTH	5
+#define TCP_METRICS_RECLAIM_PTR		(struct tcp_metrics_block *) 0x1UL
+
+#define deref_locked(p)	\
+	rcu_dereference_protected(p, lockdep_is_held(&tcp_metrics_lock))
+
+static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
+					  struct inetpeer_addr *saddr,
+					  struct inetpeer_addr *daddr,
+					  unsigned int hash)
+{
+	struct tcp_metrics_block *tm;
+	struct net *net;
+	bool reclaim = false;
+
+	spin_lock_bh(&tcp_metrics_lock);
+	net = dev_net(dst->dev);
+
+	/* While waiting for the spin-lock the cache might have been populated
+	 * with this entry and so we have to check again.
+	 */
+	tm = __tcp_get_metrics(saddr, daddr, net, hash);
+	if (tm == TCP_METRICS_RECLAIM_PTR) {
+		reclaim = true;
+		tm = NULL;
+	}
+	if (tm) {
+		tcpm_check_stamp(tm, dst);
+		goto out_unlock;
+	}
+
+	if (unlikely(reclaim)) {
+		struct tcp_metrics_block *oldest;
+
+		oldest = deref_locked(tcp_metrics_hash[hash].chain);
+		for (tm = deref_locked(oldest->tcpm_next); tm;
+		     tm = deref_locked(tm->tcpm_next)) {
+			if (time_before(READ_ONCE(tm->tcpm_stamp),
+					READ_ONCE(oldest->tcpm_stamp)))
+				oldest = tm;
+		}
+		tm = oldest;
+	} else {
+		tm = kzalloc(sizeof(*tm), GFP_ATOMIC);
+		if (!tm)
+			goto out_unlock;
+	}
+	/* Paired with the READ_ONCE() in tm_net() */
+	WRITE_ONCE(tm->tcpm_net, net);
+
+	tm->tcpm_saddr = *saddr;
+	tm->tcpm_daddr = *daddr;
+
+	tcpm_suck_dst(tm, dst, reclaim);
+
+	if (likely(!reclaim)) {
+		tm->tcpm_next = tcp_metrics_hash[hash].chain;
+		rcu_assign_pointer(tcp_metrics_hash[hash].chain, tm);
+	}
+
+out_unlock:
+	spin_unlock_bh(&tcp_metrics_lock);
+	return tm;
+}
+
+static struct tcp_metrics_block *tcp_get_encode(struct tcp_metrics_block *tm, int depth)
+{
+	if (tm)
+		return tm;
+	if (depth > TCP_METRICS_RECLAIM_DEPTH)
+		return TCP_METRICS_RECLAIM_PTR;
+	return NULL;
+}
+
+static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *saddr,
+						   const struct inetpeer_addr *daddr,
+						   struct net *net, unsigned int hash)
+{
+	struct tcp_metrics_block *tm;
+	int depth = 0;
+
+	for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
+	     tm = rcu_dereference(tm->tcpm_next)) {
+		if (addr_same(&tm->tcpm_saddr, saddr) &&
+		    addr_same(&tm->tcpm_daddr, daddr) &&
+		    net_eq(tm_net(tm), net))
+			break;
+		depth++;
+	}
+	return tcp_get_encode(tm, depth);
+}
+
+static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
+						       struct dst_entry *dst)
+{
+	struct tcp_metrics_block *tm;
+	struct inetpeer_addr saddr, daddr;
+	unsigned int hash;
+	struct net *net;
+
+	saddr.family = req->rsk_ops->family;
+	daddr.family = req->rsk_ops->family;
+	switch (daddr.family) {
+	case AF_INET:
+		inetpeer_set_addr_v4(&saddr, inet_rsk(req)->ir_loc_addr);
+		inetpeer_set_addr_v4(&daddr, inet_rsk(req)->ir_rmt_addr);
+		hash = ipv4_addr_hash(inet_rsk(req)->ir_rmt_addr);
+		break;
+#if IS_ENABLED(CONFIG_IPV6)
+	case AF_INET6:
+		inetpeer_set_addr_v6(&saddr, &inet_rsk(req)->ir_v6_loc_addr);
+		inetpeer_set_addr_v6(&daddr, &inet_rsk(req)->ir_v6_rmt_addr);
+		hash = ipv6_addr_hash(&inet_rsk(req)->ir_v6_rmt_addr);
+		break;
+#endif
+	default:
+		return NULL;
+	}
+
+	net = dev_net(dst->dev);
+	hash ^= net_hash_mix(net);
+	hash = hash_32(hash, tcp_metrics_hash_log);
+
+	for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
+	     tm = rcu_dereference(tm->tcpm_next)) {
+		if (addr_same(&tm->tcpm_saddr, &saddr) &&
+		    addr_same(&tm->tcpm_daddr, &daddr) &&
+		    net_eq(tm_net(tm), net))
+			break;
+	}
+	tcpm_check_stamp(tm, dst);
+	return tm;
+}
+
+static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
+						 struct dst_entry *dst,
+						 bool create)
+{
+	struct tcp_metrics_block *tm;
+	struct inetpeer_addr saddr, daddr;
+	unsigned int hash;
+	struct net *net;
+
+	if (sk->sk_family == AF_INET) {
+		inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
+		inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
+		hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
+	}
+#if IS_ENABLED(CONFIG_IPV6)
+	else if (sk->sk_family == AF_INET6) {
+		if (ipv6_addr_v4mapped(&sk->sk_v6_daddr)) {
+			inetpeer_set_addr_v4(&saddr, inet_sk(sk)->inet_saddr);
+			inetpeer_set_addr_v4(&daddr, inet_sk(sk)->inet_daddr);
+			hash = ipv4_addr_hash(inet_sk(sk)->inet_daddr);
+		} else {
+			inetpeer_set_addr_v6(&saddr, &sk->sk_v6_rcv_saddr);
+			inetpeer_set_addr_v6(&daddr, &sk->sk_v6_daddr);
+			hash = ipv6_addr_hash(&sk->sk_v6_daddr);
+		}
+	}
+#endif
+	else
+		return NULL;
+
+	net = dev_net(dst->dev);
+	hash ^= net_hash_mix(net);
+	hash = hash_32(hash, tcp_metrics_hash_log);
+
+	tm = __tcp_get_metrics(&saddr, &daddr, net, hash);
+	if (tm == TCP_METRICS_RECLAIM_PTR)
+		tm = NULL;
+	if (!tm && create)
+		tm = tcpm_new(dst, &saddr, &daddr, hash);
+	else
+		tcpm_check_stamp(tm, dst);
+
+	return tm;
+}
+
+/* Save metrics learned by this TCP session.  This function is called
+ * only, when TCP finishes successfully i.e. when it enters TIME-WAIT
+ * or goes from LAST-ACK to CLOSE.
+ */
+void tcp_update_metrics(struct sock *sk)
+{
+	const struct inet_connection_sock *icsk = inet_csk(sk);
+	struct dst_entry *dst = __sk_dst_get(sk);
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct net *net = sock_net(sk);
+	struct tcp_metrics_block *tm;
+	unsigned long rtt;
+	u32 val;
+	int m;
+
+	sk_dst_confirm(sk);
+	if (READ_ONCE(net->ipv4.sysctl_tcp_nometrics_save) || !dst)
+		return;
+
+	rcu_read_lock();
+	if (icsk->icsk_backoff || !tp->srtt_us) {
+		/* This session failed to estimate rtt. Why?
+		 * Probably, no packets returned in time.  Reset our
+		 * results.
+		 */
+		tm = tcp_get_metrics(sk, dst, false);
+		if (tm && !tcp_metric_locked(tm, TCP_METRIC_RTT))
+			tcp_metric_set(tm, TCP_METRIC_RTT, 0);
+		goto out_unlock;
+	} else
+		tm = tcp_get_metrics(sk, dst, true);
+
+	if (!tm)
+		goto out_unlock;
+
+	rtt = tcp_metric_get(tm, TCP_METRIC_RTT);
+	m = rtt - tp->srtt_us;
+
+	/* If newly calculated rtt larger than stored one, store new
+	 * one. Otherwise, use EWMA. Remember, rtt overestimation is
+	 * always better than underestimation.
+	 */
+	if (!tcp_metric_locked(tm, TCP_METRIC_RTT)) {
+		if (m <= 0)
+			rtt = tp->srtt_us;
+		else
+			rtt -= (m >> 3);
+		tcp_metric_set(tm, TCP_METRIC_RTT, rtt);
+	}
+
+	if (!tcp_metric_locked(tm, TCP_METRIC_RTTVAR)) {
+		unsigned long var;
+
+		if (m < 0)
+			m = -m;
+
+		/* Scale deviation to rttvar fixed point */
+		m >>= 1;
+		if (m < tp->mdev_us)
+			m = tp->mdev_us;
+
+		var = tcp_metric_get(tm, TCP_METRIC_RTTVAR);
+		if (m >= var)
+			var = m;
+		else
+			var -= (var - m) >> 2;
+
+		tcp_metric_set(tm, TCP_METRIC_RTTVAR, var);
+	}
+
+	if (tcp_in_initial_slowstart(tp)) {
+		/* Slow start still did not finish. */
+		if (!READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) &&
+		    !tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
+			val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
+			if (val && (tp->snd_cwnd >> 1) > val)
+				tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
+					       tp->snd_cwnd >> 1);
+		}
+		if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
+			val = tcp_metric_get(tm, TCP_METRIC_CWND);
+			if (tp->snd_cwnd > val)
+				tcp_metric_set(tm, TCP_METRIC_CWND,
+					       tp->snd_cwnd);
+		}
+	} else if (!tcp_in_slow_start(tp) &&
+		   icsk->icsk_ca_state == TCP_CA_Open) {
+		/* Cong. avoidance phase, cwnd is reliable. */
+		if (!READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) &&
+		    !tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
+			tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
+				       max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
+		if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
+			val = tcp_metric_get(tm, TCP_METRIC_CWND);
+			tcp_metric_set(tm, TCP_METRIC_CWND, (val + tp->snd_cwnd) >> 1);
+		}
+	} else {
+		/* Else slow start did not finish, cwnd is non-sense,
+		 * ssthresh may be also invalid.
+		 */
+		if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
+			val = tcp_metric_get(tm, TCP_METRIC_CWND);
+			tcp_metric_set(tm, TCP_METRIC_CWND,
+				       (val + tp->snd_ssthresh) >> 1);
+		}
+		if (!READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) &&
+		    !tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
+			val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
+			if (val && tp->snd_ssthresh > val)
+				tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
+					       tp->snd_ssthresh);
+		}
+		if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {
+			val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
+			if (val < tp->reordering &&
+			    tp->reordering !=
+			    READ_ONCE(net->ipv4.sysctl_tcp_reordering))
+				tcp_metric_set(tm, TCP_METRIC_REORDERING,
+					       tp->reordering);
+		}
+	}
+	WRITE_ONCE(tm->tcpm_stamp, jiffies);
+out_unlock:
+	rcu_read_unlock();
+}
+
+/* Initialize metrics on socket. */
+
+void tcp_init_metrics(struct sock *sk)
+{
+	struct dst_entry *dst = __sk_dst_get(sk);
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct net *net = sock_net(sk);
+	struct tcp_metrics_block *tm;
+	u32 val, crtt = 0; /* cached RTT scaled by 8 */
+
+	sk_dst_confirm(sk);
+	/* ssthresh may have been reduced unnecessarily during.
+	 * 3WHS. Restore it back to its initial default.
+	 */
+	tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
+	if (!dst)
+		goto reset;
+
+	rcu_read_lock();
+	tm = tcp_get_metrics(sk, dst, false);
+	if (!tm) {
+		rcu_read_unlock();
+		goto reset;
+	}
+
+	if (tcp_metric_locked(tm, TCP_METRIC_CWND))
+		tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
+
+	val = READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) ?
+	      0 : tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
+	if (val) {
+		tp->snd_ssthresh = val;
+		if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
+			tp->snd_ssthresh = tp->snd_cwnd_clamp;
+	}
+	val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
+	if (val && tp->reordering != val)
+		tp->reordering = val;
+
+	crtt = tcp_metric_get(tm, TCP_METRIC_RTT);
+	rcu_read_unlock();
+reset:
+	/* The initial RTT measurement from the SYN/SYN-ACK is not ideal
+	 * to seed the RTO for later data packets because SYN packets are
+	 * small. Use the per-dst cached values to seed the RTO but keep
+	 * the RTT estimator variables intact (e.g., srtt, mdev, rttvar).
+	 * Later the RTO will be updated immediately upon obtaining the first
+	 * data RTT sample (tcp_rtt_estimator()). Hence the cached RTT only
+	 * influences the first RTO but not later RTT estimation.
+	 *
+	 * But if RTT is not available from the SYN (due to retransmits or
+	 * syn cookies) or the cache, force a conservative 3secs timeout.
+	 *
+	 * A bit of theory. RTT is time passed after "normal" sized packet
+	 * is sent until it is ACKed. In normal circumstances sending small
+	 * packets force peer to delay ACKs and calculation is correct too.
+	 * The algorithm is adaptive and, provided we follow specs, it
+	 * NEVER underestimate RTT. BUT! If peer tries to make some clever
+	 * tricks sort of "quick acks" for time long enough to decrease RTT
+	 * to low value, and then abruptly stops to do it and starts to delay
+	 * ACKs, wait for troubles.
+	 */
+	if (crtt > tp->srtt_us) {
+		/* Set RTO like tcp_rtt_estimator(), but from cached RTT. */
+		crtt /= 8 * USEC_PER_SEC / HZ;
+		inet_csk(sk)->icsk_rto = crtt + max(2 * crtt, tcp_rto_min(sk));
+	} else if (tp->srtt_us == 0) {
+		/* RFC6298: 5.7 We've failed to get a valid RTT sample from
+		 * 3WHS. This is most likely due to retransmission,
+		 * including spurious one. Reset the RTO back to 3secs
+		 * from the more aggressive 1sec to avoid more spurious
+		 * retransmission.
+		 */
+		tp->rttvar_us = jiffies_to_usecs(TCP_TIMEOUT_FALLBACK);
+		tp->mdev_us = tp->mdev_max_us = tp->rttvar_us;
+
+		inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
+	}
+}
+
+bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst)
+{
+	struct tcp_metrics_block *tm;
+	bool ret;
+
+	if (!dst)
+		return false;
+
+	rcu_read_lock();
+	tm = __tcp_get_metrics_req(req, dst);
+	if (tm && tcp_metric_get(tm, TCP_METRIC_RTT))
+		ret = true;
+	else
+		ret = false;
+	rcu_read_unlock();
+
+	return ret;
+}
+
+void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
+			    struct tcp_fastopen_cookie *cookie)
+{
+	struct tcp_metrics_block *tm;
+
+	rcu_read_lock();
+	tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
+	if (tm) {
+		struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
+		unsigned int seq;
+
+		do {
+			seq = read_seqbegin(&fastopen_seqlock);
+			if (tfom->mss)
+				*mss = tfom->mss;
+			*cookie = tfom->cookie;
+			if (cookie->len <= 0 && tfom->try_exp == 1)
+				cookie->exp = true;
+		} while (read_seqretry(&fastopen_seqlock, seq));
+	}
+	rcu_read_unlock();
+}
+
+void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
+			    struct tcp_fastopen_cookie *cookie, bool syn_lost,
+			    u16 try_exp)
+{
+	struct dst_entry *dst = __sk_dst_get(sk);
+	struct tcp_metrics_block *tm;
+
+	if (!dst)
+		return;
+	rcu_read_lock();
+	tm = tcp_get_metrics(sk, dst, true);
+	if (tm) {
+		struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
+
+		write_seqlock_bh(&fastopen_seqlock);
+		if (mss)
+			tfom->mss = mss;
+		if (cookie && cookie->len > 0)
+			tfom->cookie = *cookie;
+		else if (try_exp > tfom->try_exp &&
+			 tfom->cookie.len <= 0 && !tfom->cookie.exp)
+			tfom->try_exp = try_exp;
+		if (syn_lost) {
+			++tfom->syn_loss;
+			tfom->last_syn_loss = jiffies;
+		} else
+			tfom->syn_loss = 0;
+		write_sequnlock_bh(&fastopen_seqlock);
+	}
+	rcu_read_unlock();
+}
+
+static struct genl_family tcp_metrics_nl_family;
+
+static const struct nla_policy tcp_metrics_nl_policy[TCP_METRICS_ATTR_MAX + 1] = {
+	[TCP_METRICS_ATTR_ADDR_IPV4]	= { .type = NLA_U32, },
+	[TCP_METRICS_ATTR_ADDR_IPV6]	= { .type = NLA_BINARY,
+					    .len = sizeof(struct in6_addr), },
+	/* Following attributes are not received for GET/DEL,
+	 * we keep them for reference
+	 */
+#if 0
+	[TCP_METRICS_ATTR_AGE]		= { .type = NLA_MSECS, },
+	[TCP_METRICS_ATTR_TW_TSVAL]	= { .type = NLA_U32, },
+	[TCP_METRICS_ATTR_TW_TS_STAMP]	= { .type = NLA_S32, },
+	[TCP_METRICS_ATTR_VALS]		= { .type = NLA_NESTED, },
+	[TCP_METRICS_ATTR_FOPEN_MSS]	= { .type = NLA_U16, },
+	[TCP_METRICS_ATTR_FOPEN_SYN_DROPS]	= { .type = NLA_U16, },
+	[TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS]	= { .type = NLA_MSECS, },
+	[TCP_METRICS_ATTR_FOPEN_COOKIE]	= { .type = NLA_BINARY,
+					    .len = TCP_FASTOPEN_COOKIE_MAX, },
+#endif
+};
+
+/* Add attributes, caller cancels its header on failure */
+static int tcp_metrics_fill_info(struct sk_buff *msg,
+				 struct tcp_metrics_block *tm)
+{
+	struct nlattr *nest;
+	int i;
+
+	switch (tm->tcpm_daddr.family) {
+	case AF_INET:
+		if (nla_put_in_addr(msg, TCP_METRICS_ATTR_ADDR_IPV4,
+				    inetpeer_get_addr_v4(&tm->tcpm_daddr)) < 0)
+			goto nla_put_failure;
+		if (nla_put_in_addr(msg, TCP_METRICS_ATTR_SADDR_IPV4,
+				    inetpeer_get_addr_v4(&tm->tcpm_saddr)) < 0)
+			goto nla_put_failure;
+		break;
+	case AF_INET6:
+		if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_ADDR_IPV6,
+				     inetpeer_get_addr_v6(&tm->tcpm_daddr)) < 0)
+			goto nla_put_failure;
+		if (nla_put_in6_addr(msg, TCP_METRICS_ATTR_SADDR_IPV6,
+				     inetpeer_get_addr_v6(&tm->tcpm_saddr)) < 0)
+			goto nla_put_failure;
+		break;
+	default:
+		return -EAFNOSUPPORT;
+	}
+
+	if (nla_put_msecs(msg, TCP_METRICS_ATTR_AGE,
+			  jiffies - READ_ONCE(tm->tcpm_stamp),
+			  TCP_METRICS_ATTR_PAD) < 0)
+		goto nla_put_failure;
+
+	{
+		int n = 0;
+
+		nest = nla_nest_start_noflag(msg, TCP_METRICS_ATTR_VALS);
+		if (!nest)
+			goto nla_put_failure;
+		for (i = 0; i < TCP_METRIC_MAX_KERNEL + 1; i++) {
+			u32 val = tcp_metric_get(tm, i);
+
+			if (!val)
+				continue;
+			if (i == TCP_METRIC_RTT) {
+				if (nla_put_u32(msg, TCP_METRIC_RTT_US + 1,
+						val) < 0)
+					goto nla_put_failure;
+				n++;
+				val = max(val / 1000, 1U);
+			}
+			if (i == TCP_METRIC_RTTVAR) {
+				if (nla_put_u32(msg, TCP_METRIC_RTTVAR_US + 1,
+						val) < 0)
+					goto nla_put_failure;
+				n++;
+				val = max(val / 1000, 1U);
+			}
+			if (nla_put_u32(msg, i + 1, val) < 0)
+				goto nla_put_failure;
+			n++;
+		}
+		if (n)
+			nla_nest_end(msg, nest);
+		else
+			nla_nest_cancel(msg, nest);
+	}
+
+	{
+		struct tcp_fastopen_metrics tfom_copy[1], *tfom;
+		unsigned int seq;
+
+		do {
+			seq = read_seqbegin(&fastopen_seqlock);
+			tfom_copy[0] = tm->tcpm_fastopen;
+		} while (read_seqretry(&fastopen_seqlock, seq));
+
+		tfom = tfom_copy;
+		if (tfom->mss &&
+		    nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_MSS,
+				tfom->mss) < 0)
+			goto nla_put_failure;
+		if (tfom->syn_loss &&
+		    (nla_put_u16(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROPS,
+				tfom->syn_loss) < 0 ||
+		     nla_put_msecs(msg, TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS,
+				jiffies - tfom->last_syn_loss,
+				TCP_METRICS_ATTR_PAD) < 0))
+			goto nla_put_failure;
+		if (tfom->cookie.len > 0 &&
+		    nla_put(msg, TCP_METRICS_ATTR_FOPEN_COOKIE,
+			    tfom->cookie.len, tfom->cookie.val) < 0)
+			goto nla_put_failure;
+	}
+
+	return 0;
+
+nla_put_failure:
+	return -EMSGSIZE;
+}
+
+static int tcp_metrics_dump_info(struct sk_buff *skb,
+				 struct netlink_callback *cb,
+				 struct tcp_metrics_block *tm)
+{
+	void *hdr;
+
+	hdr = genlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
+			  &tcp_metrics_nl_family, NLM_F_MULTI,
+			  TCP_METRICS_CMD_GET);
+	if (!hdr)
+		return -EMSGSIZE;
+
+	if (tcp_metrics_fill_info(skb, tm) < 0)
+		goto nla_put_failure;
+
+	genlmsg_end(skb, hdr);
+	return 0;
+
+nla_put_failure:
+	genlmsg_cancel(skb, hdr);
+	return -EMSGSIZE;
+}
+
+static int tcp_metrics_nl_dump(struct sk_buff *skb,
+			       struct netlink_callback *cb)
+{
+	struct net *net = sock_net(skb->sk);
+	unsigned int max_rows = 1U << tcp_metrics_hash_log;
+	unsigned int row, s_row = cb->args[0];
+	int s_col = cb->args[1], col = s_col;
+
+	for (row = s_row; row < max_rows; row++, s_col = 0) {
+		struct tcp_metrics_block *tm;
+		struct tcpm_hash_bucket *hb = tcp_metrics_hash + row;
+
+		rcu_read_lock();
+		for (col = 0, tm = rcu_dereference(hb->chain); tm;
+		     tm = rcu_dereference(tm->tcpm_next), col++) {
+			if (!net_eq(tm_net(tm), net))
+				continue;
+			if (col < s_col)
+				continue;
+			if (tcp_metrics_dump_info(skb, cb, tm) < 0) {
+				rcu_read_unlock();
+				goto done;
+			}
+		}
+		rcu_read_unlock();
+	}
+
+done:
+	cb->args[0] = row;
+	cb->args[1] = col;
+	return skb->len;
+}
+
+static int __parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
+			   unsigned int *hash, int optional, int v4, int v6)
+{
+	struct nlattr *a;
+
+	a = info->attrs[v4];
+	if (a) {
+		inetpeer_set_addr_v4(addr, nla_get_in_addr(a));
+		if (hash)
+			*hash = ipv4_addr_hash(inetpeer_get_addr_v4(addr));
+		return 0;
+	}
+	a = info->attrs[v6];
+	if (a) {
+		struct in6_addr in6;
+
+		if (nla_len(a) != sizeof(struct in6_addr))
+			return -EINVAL;
+		in6 = nla_get_in6_addr(a);
+		inetpeer_set_addr_v6(addr, &in6);
+		if (hash)
+			*hash = ipv6_addr_hash(inetpeer_get_addr_v6(addr));
+		return 0;
+	}
+	return optional ? 1 : -EAFNOSUPPORT;
+}
+
+static int parse_nl_addr(struct genl_info *info, struct inetpeer_addr *addr,
+			 unsigned int *hash, int optional)
+{
+	return __parse_nl_addr(info, addr, hash, optional,
+			       TCP_METRICS_ATTR_ADDR_IPV4,
+			       TCP_METRICS_ATTR_ADDR_IPV6);
+}
+
+static int parse_nl_saddr(struct genl_info *info, struct inetpeer_addr *addr)
+{
+	return __parse_nl_addr(info, addr, NULL, 0,
+			       TCP_METRICS_ATTR_SADDR_IPV4,
+			       TCP_METRICS_ATTR_SADDR_IPV6);
+}
+
+static int tcp_metrics_nl_cmd_get(struct sk_buff *skb, struct genl_info *info)
+{
+	struct tcp_metrics_block *tm;
+	struct inetpeer_addr saddr, daddr;
+	unsigned int hash;
+	struct sk_buff *msg;
+	struct net *net = genl_info_net(info);
+	void *reply;
+	int ret;
+	bool src = true;
+
+	ret = parse_nl_addr(info, &daddr, &hash, 0);
+	if (ret < 0)
+		return ret;
+
+	ret = parse_nl_saddr(info, &saddr);
+	if (ret < 0)
+		src = false;
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	reply = genlmsg_put_reply(msg, info, &tcp_metrics_nl_family, 0,
+				  info->genlhdr->cmd);
+	if (!reply)
+		goto nla_put_failure;
+
+	hash ^= net_hash_mix(net);
+	hash = hash_32(hash, tcp_metrics_hash_log);
+	ret = -ESRCH;
+	rcu_read_lock();
+	for (tm = rcu_dereference(tcp_metrics_hash[hash].chain); tm;
+	     tm = rcu_dereference(tm->tcpm_next)) {
+		if (addr_same(&tm->tcpm_daddr, &daddr) &&
+		    (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
+		    net_eq(tm_net(tm), net)) {
+			ret = tcp_metrics_fill_info(msg, tm);
+			break;
+		}
+	}
+	rcu_read_unlock();
+	if (ret < 0)
+		goto out_free;
+
+	genlmsg_end(msg, reply);
+	return genlmsg_reply(msg, info);
+
+nla_put_failure:
+	ret = -EMSGSIZE;
+
+out_free:
+	nlmsg_free(msg);
+	return ret;
+}
+
+static void tcp_metrics_flush_all(struct net *net)
+{
+	unsigned int max_rows = 1U << tcp_metrics_hash_log;
+	struct tcpm_hash_bucket *hb = tcp_metrics_hash;
+	struct tcp_metrics_block *tm;
+	unsigned int row;
+
+	for (row = 0; row < max_rows; row++, hb++) {
+		struct tcp_metrics_block __rcu **pp;
+		bool match;
+
+		spin_lock_bh(&tcp_metrics_lock);
+		pp = &hb->chain;
+		for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
+			match = net ? net_eq(tm_net(tm), net) :
+				!refcount_read(&tm_net(tm)->count);
+			if (match) {
+				rcu_assign_pointer(*pp, tm->tcpm_next);
+				kfree_rcu(tm, rcu_head);
+			} else {
+				pp = &tm->tcpm_next;
+			}
+		}
+		spin_unlock_bh(&tcp_metrics_lock);
+	}
+}
+
+static int tcp_metrics_nl_cmd_del(struct sk_buff *skb, struct genl_info *info)
+{
+	struct tcpm_hash_bucket *hb;
+	struct tcp_metrics_block *tm;
+	struct tcp_metrics_block __rcu **pp;
+	struct inetpeer_addr saddr, daddr;
+	unsigned int hash;
+	struct net *net = genl_info_net(info);
+	int ret;
+	bool src = true, found = false;
+
+	ret = parse_nl_addr(info, &daddr, &hash, 1);
+	if (ret < 0)
+		return ret;
+	if (ret > 0) {
+		tcp_metrics_flush_all(net);
+		return 0;
+	}
+	ret = parse_nl_saddr(info, &saddr);
+	if (ret < 0)
+		src = false;
+
+	hash ^= net_hash_mix(net);
+	hash = hash_32(hash, tcp_metrics_hash_log);
+	hb = tcp_metrics_hash + hash;
+	pp = &hb->chain;
+	spin_lock_bh(&tcp_metrics_lock);
+	for (tm = deref_locked(*pp); tm; tm = deref_locked(*pp)) {
+		if (addr_same(&tm->tcpm_daddr, &daddr) &&
+		    (!src || addr_same(&tm->tcpm_saddr, &saddr)) &&
+		    net_eq(tm_net(tm), net)) {
+			rcu_assign_pointer(*pp, tm->tcpm_next);
+			kfree_rcu(tm, rcu_head);
+			found = true;
+		} else {
+			pp = &tm->tcpm_next;
+		}
+	}
+	spin_unlock_bh(&tcp_metrics_lock);
+	if (!found)
+		return -ESRCH;
+	return 0;
+}
+
+static const struct genl_small_ops tcp_metrics_nl_ops[] = {
+	{
+		.cmd = TCP_METRICS_CMD_GET,
+		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
+		.doit = tcp_metrics_nl_cmd_get,
+		.dumpit = tcp_metrics_nl_dump,
+	},
+	{
+		.cmd = TCP_METRICS_CMD_DEL,
+		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
+		.doit = tcp_metrics_nl_cmd_del,
+		.flags = GENL_ADMIN_PERM,
+	},
+};
+
+static struct genl_family tcp_metrics_nl_family __ro_after_init = {
+	.hdrsize	= 0,
+	.name		= TCP_METRICS_GENL_NAME,
+	.version	= TCP_METRICS_GENL_VERSION,
+	.maxattr	= TCP_METRICS_ATTR_MAX,
+	.policy = tcp_metrics_nl_policy,
+	.netnsok	= true,
+	.module		= THIS_MODULE,
+	.small_ops	= tcp_metrics_nl_ops,
+	.n_small_ops	= ARRAY_SIZE(tcp_metrics_nl_ops),
+};
+
+static unsigned int tcpmhash_entries;
+static int __init set_tcpmhash_entries(char *str)
+{
+	ssize_t ret;
+
+	if (!str)
+		return 0;
+
+	ret = kstrtouint(str, 0, &tcpmhash_entries);
+	if (ret)
+		return 0;
+
+	return 1;
+}
+__setup("tcpmhash_entries=", set_tcpmhash_entries);
+
+static int __net_init tcp_net_metrics_init(struct net *net)
+{
+	size_t size;
+	unsigned int slots;
+
+	if (!net_eq(net, &init_net))
+		return 0;
+
+	slots = tcpmhash_entries;
+	if (!slots) {
+		if (totalram_pages() >= 128 * 1024)
+			slots = 16 * 1024;
+		else
+			slots = 8 * 1024;
+	}
+
+	tcp_metrics_hash_log = order_base_2(slots);
+	size = sizeof(struct tcpm_hash_bucket) << tcp_metrics_hash_log;
+
+	tcp_metrics_hash = kvzalloc(size, GFP_KERNEL);
+	if (!tcp_metrics_hash)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void __net_exit tcp_net_metrics_exit_batch(struct list_head *net_exit_list)
+{
+	tcp_metrics_flush_all(NULL);
+}
+
+static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
+	.init		=	tcp_net_metrics_init,
+	.exit_batch	=	tcp_net_metrics_exit_batch,
+};
+
+void __init tcp_metrics_init(void)
+{
+	int ret;
+
+	ret = register_pernet_subsys(&tcp_net_metrics_ops);
+	if (ret < 0)
+		panic("Could not allocate the tcp_metrics hash table\n");
+
+	ret = genl_register_family(&tcp_metrics_nl_family);
+	if (ret < 0)
+		panic("Could not register tcp_metrics generic netlink\n");
+}