1 files changed, 150 insertions, 227 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 509912a5ff98..536d40929ba6 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -65,28 +65,24 @@ int sysctl_tcp_base_mss __read_mostly = TCP_BASE_MSS;
 /* By default, RFC2861 behavior.  */
 int sysctl_tcp_slow_start_after_idle __read_mostly = 1;
 
-int sysctl_tcp_cookie_size __read_mostly = 0; /* TCP_COOKIE_MAX */
-EXPORT_SYMBOL_GPL(sysctl_tcp_cookie_size);
-
 static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
                            int push_one, gfp_t gfp);
 
 /* Account for new data that has been sent to the network. */
 static void tcp_event_new_data_sent(struct sock *sk, const struct sk_buff *skb)
 {
+        struct inet_connection_sock *icsk = inet_csk(sk);
         struct tcp_sock *tp = tcp_sk(sk);
         unsigned int prior_packets = tp->packets_out;
 
         tcp_advance_send_head(sk, skb);
         tp->snd_nxt = TCP_SKB_CB(skb)->end_seq;
 
-        /* Don't override Nagle indefinitely with F-RTO */
-        if (tp->frto_counter == 2)
-                tp->frto_counter = 3;
-
         tp->packets_out += tcp_skb_pcount(skb);
-        if (!prior_packets || tp->early_retrans_delayed)
+        if (!prior_packets || icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS ||
+            icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) {
                 tcp_rearm_rto(sk);
+        }
 }
 
 /* SND.NXT, if window was not shrunk.
@@ -384,7 +380,6 @@ static inline bool tcp_urg_mode(const struct tcp_sock *tp)
 #define OPTION_TS               (1 << 1)
 #define OPTION_MD5              (1 << 2)
 #define OPTION_WSCALE           (1 << 3)
-#define OPTION_COOKIE_EXTENSION (1 << 4)
 #define OPTION_FAST_OPEN_COOKIE (1 << 8)
 
 struct tcp_out_options {
@@ -398,36 +393,6 @@ struct tcp_out_options {
         struct tcp_fastopen_cookie *fastopen_cookie;    /* Fast open cookie */
 };
 
-/* The sysctl int routines are generic, so check consistency here.
- */
-static u8 tcp_cookie_size_check(u8 desired)
-{
-        int cookie_size;
-
-        if (desired > 0)
-                /* previously specified */
-                return desired;
-
-        cookie_size = ACCESS_ONCE(sysctl_tcp_cookie_size);
-        if (cookie_size <= 0)
-                /* no default specified */
-                return 0;
-
-        if (cookie_size <= TCP_COOKIE_MIN)
-                /* value too small, specify minimum */
-                return TCP_COOKIE_MIN;
-
-        if (cookie_size >= TCP_COOKIE_MAX)
-                /* value too large, specify maximum */
-                return TCP_COOKIE_MAX;
-
-        if (cookie_size & 1)
-                /* 8-bit multiple, illegal, fix it */
-                cookie_size++;
-
-        return (u8)cookie_size;
-}
-
 /* Write previously computed TCP options to the packet.
  *
  * Beware: Something in the Internet is very sensitive to the ordering of
@@ -446,27 +411,9 @@ static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
 {
         u16 options = opts->options;    /* mungable copy */
 
-        /* Having both authentication and cookies for security is redundant,
-         * and there's certainly not enough room.  Instead, the cookie-less
-         * extension variant is proposed.
-         *
-         * Consider the pessimal case with authentication.  The options
-         * could look like:
-         *   COOKIE|MD5(20) + MSS(4) + SACK|TS(12) + WSCALE(4) == 40
-         */
         if (unlikely(OPTION_MD5 & options)) {
-                if (unlikely(OPTION_COOKIE_EXTENSION & options)) {
-                        *ptr++ = htonl((TCPOPT_COOKIE << 24) |
-                                       (TCPOLEN_COOKIE_BASE << 16) |
-                                       (TCPOPT_MD5SIG << 8) |
-                                       TCPOLEN_MD5SIG);
-                } else {
-                        *ptr++ = htonl((TCPOPT_NOP << 24) |
-                                       (TCPOPT_NOP << 16) |
-                                       (TCPOPT_MD5SIG << 8) |
-                                       TCPOLEN_MD5SIG);
-                }
-                options &= ~OPTION_COOKIE_EXTENSION;
+                *ptr++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
+                               (TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG);
                 /* overload cookie hash location */
                 opts->hash_location = (__u8 *)ptr;
                 ptr += 4;
@@ -495,44 +442,6 @@ static void tcp_options_write(__be32 *ptr, struct tcp_sock *tp,
                 *ptr++ = htonl(opts->tsecr);
         }
 
-        /* Specification requires after timestamp, so do it now.
-         *
-         * Consider the pessimal case without authentication.  The options
-         * could look like:
-         *   MSS(4) + SACK|TS(12) + COOKIE(20) + WSCALE(4) == 40
-         */
-        if (unlikely(OPTION_COOKIE_EXTENSION & options)) {
-                __u8 *cookie_copy = opts->hash_location;
-                u8 cookie_size = opts->hash_size;
-
-                /* 8-bit multiple handled in tcp_cookie_size_check() above,
-                 * and elsewhere.
-                 */
-                if (0x2 & cookie_size) {
-                        __u8 *p = (__u8 *)ptr;
-
-                        /* 16-bit multiple */
-                        *p++ = TCPOPT_COOKIE;
-                        *p++ = TCPOLEN_COOKIE_BASE + cookie_size;
-                        *p++ = *cookie_copy++;
-                        *p++ = *cookie_copy++;
-                        ptr++;
-                        cookie_size -= 2;
-                } else {
-                        /* 32-bit multiple */
-                        *ptr++ = htonl(((TCPOPT_NOP << 24) |
-                                        (TCPOPT_NOP << 16) |
-                                        (TCPOPT_COOKIE << 8) |
-                                        TCPOLEN_COOKIE_BASE) +
-                                       cookie_size);
-                }
-
-                if (cookie_size > 0) {
-                        memcpy(ptr, cookie_copy, cookie_size);
-                        ptr += (cookie_size / 4);
-                }
-        }
-
         if (unlikely(OPTION_SACK_ADVERTISE & options)) {
                 *ptr++ = htonl((TCPOPT_NOP << 24) |
                                (TCPOPT_NOP << 16) |
@@ -591,11 +500,7 @@ static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
                                 struct tcp_md5sig_key **md5)
 {
         struct tcp_sock *tp = tcp_sk(sk);
-        struct tcp_cookie_values *cvp = tp->cookie_values;
         unsigned int remaining = MAX_TCP_OPTION_SPACE;
-        u8 cookie_size = (!tp->rx_opt.cookie_out_never && cvp != NULL) ?
-                         tcp_cookie_size_check(cvp->cookie_desired) :
-                         0;
         struct tcp_fastopen_request *fastopen = tp->fastopen_req;
 
 #ifdef CONFIG_TCP_MD5SIG
@@ -647,52 +552,7 @@ static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
                         tp->syn_fastopen = 1;
                 }
         }
-        /* Note that timestamps are required by the specification.
-         *
-         * Odd numbers of bytes are prohibited by the specification, ensuring
-         * that the cookie is 16-bit aligned, and the resulting cookie pair is
-         * 32-bit aligned.
-         */
-        if (*md5 == NULL &&
-            (OPTION_TS & opts->options) &&
-            cookie_size > 0) {
-                int need = TCPOLEN_COOKIE_BASE + cookie_size;
-
-                if (0x2 & need) {
-                        /* 32-bit multiple */
-                        need += 2; /* NOPs */
-
-                        if (need > remaining) {
-                                /* try shrinking cookie to fit */
-                                cookie_size -= 2;
-                                need -= 4;
-                        }
-                }
-                while (need > remaining && TCP_COOKIE_MIN <= cookie_size) {
-                        cookie_size -= 4;
-                        need -= 4;
-                }
-                if (TCP_COOKIE_MIN <= cookie_size) {
-                        opts->options |= OPTION_COOKIE_EXTENSION;
-                        opts->hash_location = (__u8 *)&cvp->cookie_pair[0];
-                        opts->hash_size = cookie_size;
-
-                        /* Remember for future incarnations. */
-                        cvp->cookie_desired = cookie_size;
-
-                        if (cvp->cookie_desired != cvp->cookie_pair_size) {
-                                /* Currently use random bytes as a nonce,
-                                 * assuming these are completely unpredictable
-                                 * by hostile users of the same system.
-                                 */
-                                get_random_bytes(&cvp->cookie_pair[0],
-                                                 cookie_size);
-                                cvp->cookie_pair_size = cookie_size;
-                        }
 
-                        remaining -= need;
-                }
-        }
         return MAX_TCP_OPTION_SPACE - remaining;
 }
 
@@ -702,14 +562,10 @@ static unsigned int tcp_synack_options(struct sock *sk,
                                    unsigned int mss, struct sk_buff *skb,
                                    struct tcp_out_options *opts,
                                    struct tcp_md5sig_key **md5,
-                                   struct tcp_extend_values *xvp,
                                    struct tcp_fastopen_cookie *foc)
 {
         struct inet_request_sock *ireq = inet_rsk(req);
         unsigned int remaining = MAX_TCP_OPTION_SPACE;
-        u8 cookie_plus = (xvp != NULL && !xvp->cookie_out_never) ?
-                         xvp->cookie_plus :
-                         0;
 
 #ifdef CONFIG_TCP_MD5SIG
         *md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req);
@@ -757,28 +613,7 @@ static unsigned int tcp_synack_options(struct sock *sk,
                         remaining -= need;
                 }
         }
-        /* Similar rationale to tcp_syn_options() applies here, too.
-         * If the <SYN> options fit, the same options should fit now!
-         */
-        if (*md5 == NULL &&
-            ireq->tstamp_ok &&
-            cookie_plus > TCPOLEN_COOKIE_BASE) {
-                int need = cookie_plus; /* has TCPOLEN_COOKIE_BASE */
-
-                if (0x2 & need) {
-                        /* 32-bit multiple */
-                        need += 2; /* NOPs */
-                }
-                if (need <= remaining) {
-                        opts->options |= OPTION_COOKIE_EXTENSION;
-                        opts->hash_size = cookie_plus - TCPOLEN_COOKIE_BASE;
-                        remaining -= need;
-                } else {
-                        /* There's no error return, so flag it. */
-                        xvp->cookie_out_never = 1; /* true */
-                        opts->hash_size = 0;
-                }
-        }
+
         return MAX_TCP_OPTION_SPACE - remaining;
 }
 
@@ -953,7 +788,7 @@ void __init tcp_tasklet_init(void)
  * We cant xmit new skbs from this context, as we might already
  * hold qdisc lock.
  */
-static void tcp_wfree(struct sk_buff *skb)
+void tcp_wfree(struct sk_buff *skb)
 {
         struct sock *sk = skb->sk;
         struct tcp_sock *tp = tcp_sk(sk);
@@ -1012,6 +847,13 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
                 __net_timestamp(skb);
 
         if (likely(clone_it)) {
+                const struct sk_buff *fclone = skb + 1;
+
+                if (unlikely(skb->fclone == SKB_FCLONE_ORIG &&
+                             fclone->fclone == SKB_FCLONE_CLONE))
+                        NET_INC_STATS_BH(sock_net(sk),
+                                         LINUX_MIB_TCPSPURIOUS_RTX_HOSTQUEUES);
+
                 if (unlikely(skb_cloned(skb)))
                         skb = pskb_copy(skb, gfp_mask);
                 else
@@ -1632,11 +1474,8 @@ static inline bool tcp_nagle_test(const struct tcp_sock *tp, const struct sk_buf
         if (nonagle & TCP_NAGLE_PUSH)
                 return true;
 
-        /* Don't use the nagle rule for urgent data (or for the final FIN).
-         * Nagle can be ignored during F-RTO too (see RFC4138).
-         */
-        if (tcp_urg_mode(tp) || (tp->frto_counter == 2) ||
-            (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
+        /* Don't use the nagle rule for urgent data (or for the final FIN). */
+        if (tcp_urg_mode(tp) || (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
                 return true;
 
         if (!tcp_nagle_check(tp, skb, cur_mss, nonagle))
@@ -1961,6 +1800,9 @@ static int tcp_mtu_probe(struct sock *sk)
  * snd_up-64k-mss .. snd_up cannot be large. However, taking into
  * account rare use of URG, this is not a big flaw.
  *
+ * Send at most one packet when push_one > 0. Temporarily ignore
+ * cwnd limit to force at most one packet out when push_one == 2.
+
  * Returns true, if no segments are in flight and we have queued segments,
  * but cannot send anything now because of SWS or another problem.
  */
@@ -1996,8 +1838,13 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
                         goto repair; /* Skip network transmission */
 
                 cwnd_quota = tcp_cwnd_test(tp, skb);
-                if (!cwnd_quota)
-                        break;
+                if (!cwnd_quota) {
+                        if (push_one == 2)
+                                /* Force out a loss probe pkt. */
+                                cwnd_quota = 1;
+                        else
+                                break;
+                }
 
                 if (unlikely(!tcp_snd_wnd_test(tp, skb, mss_now)))
                         break;
@@ -2051,10 +1898,129 @@ repair:
         if (likely(sent_pkts)) {
                 if (tcp_in_cwnd_reduction(sk))
                         tp->prr_out += sent_pkts;
+
+                /* Send one loss probe per tail loss episode. */
+                if (push_one != 2)
+                        tcp_schedule_loss_probe(sk);
                 tcp_cwnd_validate(sk);
                 return false;
         }
-        return !tp->packets_out && tcp_send_head(sk);
+        return (push_one == 2) || (!tp->packets_out && tcp_send_head(sk));
+}
+
+bool tcp_schedule_loss_probe(struct sock *sk)
+{
+        struct inet_connection_sock *icsk = inet_csk(sk);
+        struct tcp_sock *tp = tcp_sk(sk);
+        u32 timeout, tlp_time_stamp, rto_time_stamp;
+        u32 rtt = tp->srtt >> 3;
+
+        if (WARN_ON(icsk->icsk_pending == ICSK_TIME_EARLY_RETRANS))
+                return false;
+        /* No consecutive loss probes. */
+        if (WARN_ON(icsk->icsk_pending == ICSK_TIME_LOSS_PROBE)) {
+                tcp_rearm_rto(sk);
+                return false;
+        }
+        /* Don't do any loss probe on a Fast Open connection before 3WHS
+         * finishes.
+         */
+        if (sk->sk_state == TCP_SYN_RECV)
+                return false;
+
+        /* TLP is only scheduled when next timer event is RTO. */
+        if (icsk->icsk_pending != ICSK_TIME_RETRANS)
+                return false;
+
+        /* Schedule a loss probe in 2*RTT for SACK capable connections
+         * in Open state, that are either limited by cwnd or application.
+         */
+        if (sysctl_tcp_early_retrans < 3 || !rtt || !tp->packets_out ||
+            !tcp_is_sack(tp) || inet_csk(sk)->icsk_ca_state != TCP_CA_Open)
+                return false;
+
+        if ((tp->snd_cwnd > tcp_packets_in_flight(tp)) &&
+             tcp_send_head(sk))
+                return false;
+
+        /* Probe timeout is at least 1.5*rtt + TCP_DELACK_MAX to account
+         * for delayed ack when there's one outstanding packet.
+         */
+        timeout = rtt << 1;
+        if (tp->packets_out == 1)
+                timeout = max_t(u32, timeout,
+                                (rtt + (rtt >> 1) + TCP_DELACK_MAX));
+        timeout = max_t(u32, timeout, msecs_to_jiffies(10));
+
+        /* If RTO is shorter, just schedule TLP in its place. */
+        tlp_time_stamp = tcp_time_stamp + timeout;
+        rto_time_stamp = (u32)inet_csk(sk)->icsk_timeout;
+        if ((s32)(tlp_time_stamp - rto_time_stamp) > 0) {
+                s32 delta = rto_time_stamp - tcp_time_stamp;
+                if (delta > 0)
+                        timeout = delta;
+        }
+
+        inet_csk_reset_xmit_timer(sk, ICSK_TIME_LOSS_PROBE, timeout,
+                                  TCP_RTO_MAX);
+        return true;
+}
+
+/* When probe timeout (PTO) fires, send a new segment if one exists, else
+ * retransmit the last segment.
+ */
+void tcp_send_loss_probe(struct sock *sk)
+{
+        struct tcp_sock *tp = tcp_sk(sk);
+        struct sk_buff *skb;
+        int pcount;
+        int mss = tcp_current_mss(sk);
+        int err = -1;
+
+        if (tcp_send_head(sk) != NULL) {
+                err = tcp_write_xmit(sk, mss, TCP_NAGLE_OFF, 2, GFP_ATOMIC);
+                goto rearm_timer;
+        }
+
+        /* At most one outstanding TLP retransmission. */
+        if (tp->tlp_high_seq)
+                goto rearm_timer;
+
+        /* Retransmit last segment. */
+        skb = tcp_write_queue_tail(sk);
+        if (WARN_ON(!skb))
+                goto rearm_timer;
+
+        pcount = tcp_skb_pcount(skb);
+        if (WARN_ON(!pcount))
+                goto rearm_timer;
+
+        if ((pcount > 1) && (skb->len > (pcount - 1) * mss)) {
+                if (unlikely(tcp_fragment(sk, skb, (pcount - 1) * mss, mss)))
+                        goto rearm_timer;
+                skb = tcp_write_queue_tail(sk);
+        }
+
+        if (WARN_ON(!skb || !tcp_skb_pcount(skb)))
+                goto rearm_timer;
+
+        /* Probe with zero data doesn't trigger fast recovery. */
+        if (skb->len > 0)
+                err = __tcp_retransmit_skb(sk, skb);
+
+        /* Record snd_nxt for loss detection. */
+        if (likely(!err))
+                tp->tlp_high_seq = tp->snd_nxt;
+
+rearm_timer:
+        inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
+                                  inet_csk(sk)->icsk_rto,
+                                  TCP_RTO_MAX);
+
+        if (likely(!err))
+                NET_INC_STATS_BH(sock_net(sk),
+                                 LINUX_MIB_TCPLOSSPROBES);
+        return;
 }
 
 /* Push out any pending frames which were held back due to
@@ -2679,32 +2645,24 @@ int tcp_send_synack(struct sock *sk)
  * sk: listener socket
  * dst: dst entry attached to the SYNACK
  * req: request_sock pointer
- * rvp: request_values pointer
  *
  * Allocate one skb and build a SYNACK packet.
  * @dst is consumed : Caller should not use it again.
  */
 struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
                                 struct request_sock *req,
-                                struct request_values *rvp,
                                 struct tcp_fastopen_cookie *foc)
 {
         struct tcp_out_options opts;
-        struct tcp_extend_values *xvp = tcp_xv(rvp);
         struct inet_request_sock *ireq = inet_rsk(req);
         struct tcp_sock *tp = tcp_sk(sk);
-        const struct tcp_cookie_values *cvp = tp->cookie_values;
         struct tcphdr *th;
         struct sk_buff *skb;
         struct tcp_md5sig_key *md5;
         int tcp_header_size;
         int mss;
-        int s_data_desired = 0;
 
-        if (cvp != NULL && cvp->s_data_constant && cvp->s_data_desired)
-                s_data_desired = cvp->s_data_desired;
-        skb = alloc_skb(MAX_TCP_HEADER + 15 + s_data_desired,
-                        sk_gfp_atomic(sk, GFP_ATOMIC));
+        skb = alloc_skb(MAX_TCP_HEADER + 15, sk_gfp_atomic(sk, GFP_ATOMIC));
         if (unlikely(!skb)) {
                 dst_release(dst);
                 return NULL;
@@ -2747,9 +2705,8 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
         else
 #endif
         TCP_SKB_CB(skb)->when = tcp_time_stamp;
-        tcp_header_size = tcp_synack_options(sk, req, mss,
-                                             skb, &opts, &md5, xvp, foc)
-                        + sizeof(*th);
+        tcp_header_size = tcp_synack_options(sk, req, mss, skb, &opts, &md5,
+                                             foc) + sizeof(*th);
 
         skb_push(skb, tcp_header_size);
         skb_reset_transport_header(skb);
@@ -2767,40 +2724,6 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
         tcp_init_nondata_skb(skb, tcp_rsk(req)->snt_isn,
                              TCPHDR_SYN | TCPHDR_ACK);
 
-        if (OPTION_COOKIE_EXTENSION & opts.options) {
-                if (s_data_desired) {
-                        u8 *buf = skb_put(skb, s_data_desired);
-
-                        /* copy data directly from the listening socket. */
-                        memcpy(buf, cvp->s_data_payload, s_data_desired);
-                        TCP_SKB_CB(skb)->end_seq += s_data_desired;
-                }
-
-                if (opts.hash_size > 0) {
-                        __u32 workspace[SHA_WORKSPACE_WORDS];
-                        u32 *mess = &xvp->cookie_bakery[COOKIE_DIGEST_WORDS];
-                        u32 *tail = &mess[COOKIE_MESSAGE_WORDS-1];
-
-                        /* Secret recipe depends on the Timestamp, (future)
-                         * Sequence and Acknowledgment Numbers, Initiator
-                         * Cookie, and others handled by IP variant caller.
-                         */
-                        *tail-- ^= opts.tsval;
-                        *tail-- ^= tcp_rsk(req)->rcv_isn + 1;
-                        *tail-- ^= TCP_SKB_CB(skb)->seq + 1;
-
-                        /* recommended */
-                        *tail-- ^= (((__force u32)th->dest << 16) | (__force u32)th->source);
-                        *tail-- ^= (u32)(unsigned long)cvp; /* per sockopt */
-
-                        sha_transform((__u32 *)&xvp->cookie_bakery[0],
-                                      (char *)mess,
-                                      &workspace[0]);
-                        opts.hash_location =
-                                (__u8 *)&xvp->cookie_bakery[0];
-                }
-        }
-
         th->seq = htonl(TCP_SKB_CB(skb)->seq);
         /* XXX data is queued and acked as is. No buffer/window check */
         th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt);