5 files changed, 56 insertions, 44 deletions

diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index 743d85fcd651..1c2e3ec2eb57 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -226,7 +226,7 @@ static inline void dccp_csum_outgoing(struct sk_buff *skb)
 
 extern void dccp_v4_send_check(struct sock *sk, int len, struct sk_buff *skb);
 
-extern int  dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb);
+extern int  dccp_retransmit_skb(struct sock *sk);
 
 extern void dccp_send_ack(struct sock *sk);
 extern void dccp_reqsk_send_ack(struct sk_buff *sk, struct request_sock *rsk);
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index a835b88237cb..882c5c4de69e 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -196,8 +196,8 @@ static inline void dccp_do_pmtu_discovery(struct sock *sk,
 static void dccp_v4_err(struct sk_buff *skb, u32 info)
 {
         const struct iphdr *iph = (struct iphdr *)skb->data;
-        const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data +
-                                                        (iph->ihl << 2));
+        const u8 offset = iph->ihl << 2;
+        const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset);
         struct dccp_sock *dp;
         struct inet_sock *inet;
         const int type = icmp_hdr(skb)->type;
@@ -207,7 +207,8 @@ static void dccp_v4_err(struct sk_buff *skb, u32 info)
         int err;
         struct net *net = dev_net(skb->dev);
 
-        if (skb->len < (iph->ihl << 2) + 8) {
+        if (skb->len < offset + sizeof(*dh) ||
+            skb->len < offset + __dccp_basic_hdr_len(dh)) {
                 ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
                 return;
         }
@@ -238,7 +239,7 @@ static void dccp_v4_err(struct sk_buff *skb, u32 info)
         dp = dccp_sk(sk);
         seq = dccp_hdr_seq(dh);
         if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
-            !between48(seq, dp->dccps_swl, dp->dccps_swh)) {
+            !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
                 NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
                 goto out;
         }
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index da509127e00c..5e1ee0da2c40 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -89,12 +89,19 @@ static void dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 {
         struct ipv6hdr *hdr = (struct ipv6hdr *)skb->data;
         const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset);
+        struct dccp_sock *dp;
         struct ipv6_pinfo *np;
         struct sock *sk;
         int err;
         __u64 seq;
         struct net *net = dev_net(skb->dev);
 
+        if (skb->len < offset + sizeof(*dh) ||
+            skb->len < offset + __dccp_basic_hdr_len(dh)) {
+                ICMP6_INC_STATS_BH(__in6_dev_get(skb->dev), ICMP6_MIB_INERRORS);
+                return;
+        }
+
         sk = inet6_lookup(net, &dccp_hashinfo,
                         &hdr->daddr, dh->dccph_dport,
                         &hdr->saddr, dh->dccph_sport, inet6_iif(skb));
@@ -116,6 +123,14 @@ static void dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
         if (sk->sk_state == DCCP_CLOSED)
                 goto out;
 
+        dp = dccp_sk(sk);
+        seq = dccp_hdr_seq(dh);
+        if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_LISTEN) &&
+            !between48(seq, dp->dccps_awl, dp->dccps_awh)) {
+                NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
+                goto out;
+        }
+
         np = inet6_sk(sk);
 
         if (type == ICMPV6_PKT_TOOBIG) {
@@ -168,7 +183,6 @@ static void dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 
         icmpv6_err_convert(type, code, &err);
 
-        seq = dccp_hdr_seq(dh);
         /* Might be for an request_sock */
         switch (sk->sk_state) {
                 struct request_sock *req, **prev;
diff --git a/net/dccp/output.c b/net/dccp/output.c
index fe20068c5d8e..d06945c7d3df 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -53,8 +53,11 @@ static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb)
                                           dccp_packet_hdr_len(dcb->dccpd_type);
                 int err, set_ack = 1;
                 u64 ackno = dp->dccps_gsr;
-
-                dccp_inc_seqno(&dp->dccps_gss);
+                /*
+                 * Increment GSS here already in case the option code needs it.
+                 * Update GSS for real only if option processing below succeeds.
+                 */
+                dcb->dccpd_seq = ADD48(dp->dccps_gss, 1);
 
                 switch (dcb->dccpd_type) {
                 case DCCP_PKT_DATA:
@@ -66,6 +69,9 @@ static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb)
 
                 case DCCP_PKT_REQUEST:
                         set_ack = 0;
+                        /* Use ISS on the first (non-retransmitted) Request. */
+                        if (icsk->icsk_retransmits == 0)
+                                dcb->dccpd_seq = dp->dccps_iss;
                         /* fall through */
 
                 case DCCP_PKT_SYNC:
@@ -84,8 +90,6 @@ static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb)
                         break;
                 }
 
-                dcb->dccpd_seq = dp->dccps_gss;
-
                 if (dccp_insert_options(sk, skb)) {
                         kfree_skb(skb);
                         return -EPROTO;
@@ -103,7 +107,7 @@ static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb)
                 /* XXX For now we're using only 48 bits sequence numbers */
                 dh->dccph_x     = 1;
 
-                dp->dccps_awh = dp->dccps_gss;
+                dccp_update_gss(sk, dcb->dccpd_seq);
                 dccp_hdr_set_seq(dh, dp->dccps_gss);
                 if (set_ack)
                         dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
@@ -112,6 +116,11 @@ static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb)
                 case DCCP_PKT_REQUEST:
                         dccp_hdr_request(skb)->dccph_req_service =
                                                         dp->dccps_service;
+                        /*
+                         * Limit Ack window to ISS <= P.ackno <= GSS, so that
+                         * only Responses to Requests we sent are considered.
+                         */
+                        dp->dccps_awl = dp->dccps_iss;
                         break;
                 case DCCP_PKT_RESET:
                         dccp_hdr_reset(skb)->dccph_reset_code =
@@ -284,14 +293,26 @@ void dccp_write_xmit(struct sock *sk, int block)
         }
 }
 
-int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
+/**
+ * dccp_retransmit_skb  -  Retransmit Request, Close, or CloseReq packets
+ * There are only four retransmittable packet types in DCCP:
+ * - Request  in client-REQUEST  state (sec. 8.1.1),
+ * - CloseReq in server-CLOSEREQ state (sec. 8.3),
+ * - Close    in   node-CLOSING  state (sec. 8.3),
+ * - Acks in client-PARTOPEN state (sec. 8.1.5, handled by dccp_delack_timer()).
+ * This function expects sk->sk_send_head to contain the original skb.
+ */
+int dccp_retransmit_skb(struct sock *sk)
 {
+        WARN_ON(sk->sk_send_head == NULL);
+
         if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk) != 0)
                 return -EHOSTUNREACH; /* Routing failure or similar. */
 
-        return dccp_transmit_skb(sk, (skb_cloned(skb) ?
-                                      pskb_copy(skb, GFP_ATOMIC):
-                                      skb_clone(skb, GFP_ATOMIC)));
+        /* this count is used to distinguish original and retransmitted skb */
+        inet_csk(sk)->icsk_retransmits++;
+
+        return dccp_transmit_skb(sk, skb_clone(sk->sk_send_head, GFP_ATOMIC));
 }
 
 struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
@@ -437,19 +458,7 @@ static inline void dccp_connect_init(struct sock *sk)
 
         dccp_sync_mss(sk, dst_mtu(dst));
 
-        /*
-         * SWL and AWL are initially adjusted so that they are not less than
-         * the initial Sequence Numbers received and sent, respectively:
-         *      SWL := max(GSR + 1 - floor(W/4), ISR),
-         *      AWL := max(GSS - W' + 1, ISS).
-         * These adjustments MUST be applied only at the beginning of the
-         * connection.
-         */
-        dccp_update_gss(sk, dp->dccps_iss);
-        dccp_set_seqno(&dp->dccps_awl, max48(dp->dccps_awl, dp->dccps_iss));
-
-        /* S.GAR - greatest valid acknowledgement number received on a non-Sync;
-         *         initialized to S.ISS (sec. 8.5)                            */
+        /* Initialise GAR as per 8.5; AWL/AWH are set in dccp_transmit_skb() */
         dp->dccps_gar = dp->dccps_iss;
 
         icsk->icsk_retransmits = 0;
diff --git a/net/dccp/timer.c b/net/dccp/timer.c
index 6a5b961b6f5c..54b3c7e9e016 100644
--- a/net/dccp/timer.c
+++ b/net/dccp/timer.c
@@ -99,21 +99,11 @@ static void dccp_retransmit_timer(struct sock *sk)
         }
 
         /*
-         * sk->sk_send_head has to have one skb with
-         * DCCP_SKB_CB(skb)->dccpd_type set to one of the retransmittable DCCP
-         * packet types. The only packets eligible for retransmission are:
-         *      -- Requests in client-REQUEST  state (sec. 8.1.1)
-         *      -- Acks     in client-PARTOPEN state (sec. 8.1.5)
-         *      -- CloseReq in server-CLOSEREQ state (sec. 8.3)
-         *      -- Close    in   node-CLOSING  state (sec. 8.3)                */
-        WARN_ON(sk->sk_send_head == NULL);
-
-        /*
          * More than than 4MSL (8 minutes) has passed, a RESET(aborted) was
          * sent, no need to retransmit, this sock is dead.
          */
         if (dccp_write_timeout(sk))
-                goto out;
+                return;
 
         /*
          * We want to know the number of packets retransmitted, not the
@@ -122,30 +112,28 @@ static void dccp_retransmit_timer(struct sock *sk)
         if (icsk->icsk_retransmits == 0)
                 DCCP_INC_STATS_BH(DCCP_MIB_TIMEOUTS);
 
-        if (dccp_retransmit_skb(sk, sk->sk_send_head) < 0) {
+        if (dccp_retransmit_skb(sk) != 0) {
                 /*
                  * Retransmission failed because of local congestion,
                  * do not backoff.
                  */
-                if (icsk->icsk_retransmits == 0)
+                if (--icsk->icsk_retransmits == 0)
                         icsk->icsk_retransmits = 1;
                 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
                                           min(icsk->icsk_rto,
                                               TCP_RESOURCE_PROBE_INTERVAL),
                                           DCCP_RTO_MAX);
-                goto out;
+                return;
         }
 
 backoff:
         icsk->icsk_backoff++;
-        icsk->icsk_retransmits++;
 
         icsk->icsk_rto = min(icsk->icsk_rto << 1, DCCP_RTO_MAX);
         inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto,
                                   DCCP_RTO_MAX);
         if (icsk->icsk_retransmits > sysctl_dccp_retries1)
                 __sk_dst_reset(sk);
-out:;
 }
 
 static void dccp_write_timer(unsigned long data)