7 files changed, 42 insertions, 9 deletions

diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 4370f4246e86..073273b751f8 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -287,6 +287,7 @@ static const struct snmp_mib snmp4_net_list[] = {
         SNMP_MIB_ITEM("TCPAckCompressed", LINUX_MIB_TCPACKCOMPRESSED),
         SNMP_MIB_ITEM("TCPZeroWindowDrop", LINUX_MIB_TCPZEROWINDOWDROP),
         SNMP_MIB_ITEM("TCPRcvQDrop", LINUX_MIB_TCPRCVQDROP),
+        SNMP_MIB_ITEM("TCPWqueueTooBig", LINUX_MIB_TCPWQUEUETOOBIG),
         SNMP_MIB_SENTINEL
 };
 
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index fa213bd8e233..b6f14af926fa 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -39,6 +39,8 @@ static int ip_local_port_range_min[] = { 1, 1 };
 static int ip_local_port_range_max[] = { 65535, 65535 };
 static int tcp_adv_win_scale_min = -31;
 static int tcp_adv_win_scale_max = 31;
+static int tcp_min_snd_mss_min = TCP_MIN_SND_MSS;
+static int tcp_min_snd_mss_max = 65535;
 static int ip_privileged_port_min;
 static int ip_privileged_port_max = 65535;
 static int ip_ttl_min = 1;
@@ -770,6 +772,15 @@ static struct ctl_table ipv4_net_table[] = {
                 .proc_handler   = proc_dointvec,
         },
         {
+                .procname       = "tcp_min_snd_mss",
+                .data           = &init_net.ipv4.sysctl_tcp_min_snd_mss,
+                .maxlen         = sizeof(int),
+                .mode           = 0644,
+                .proc_handler   = proc_dointvec_minmax,
+                .extra1         = &tcp_min_snd_mss_min,
+                .extra2         = &tcp_min_snd_mss_max,
+        },
+        {
                 .procname       = "tcp_probe_threshold",
                 .data           = &init_net.ipv4.sysctl_tcp_probe_threshold,
                 .maxlen         = sizeof(int),
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index f448a288d158..7dc9ab84bb69 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3873,6 +3873,7 @@ void __init tcp_init(void)
         unsigned long limit;
         unsigned int i;
 
+        BUILD_BUG_ON(TCP_MIN_SND_MSS <= MAX_TCP_OPTION_SPACE);
         BUILD_BUG_ON(sizeof(struct tcp_skb_cb) >
                      FIELD_SIZEOF(struct sk_buff, cb));
 
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 38dfc308c0fb..d95ee40df6c2 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1302,7 +1302,7 @@ static bool tcp_shifted_skb(struct sock *sk, struct sk_buff *prev,
         TCP_SKB_CB(skb)->seq += shifted;
 
         tcp_skb_pcount_add(prev, pcount);
-        BUG_ON(tcp_skb_pcount(skb) < pcount);
+        WARN_ON_ONCE(tcp_skb_pcount(skb) < pcount);
         tcp_skb_pcount_add(skb, -pcount);
 
         /* When we're adding to gso_segs == 1, gso_size will be zero,
@@ -1368,6 +1368,21 @@ static int skb_can_shift(const struct sk_buff *skb)
         return !skb_headlen(skb) && skb_is_nonlinear(skb);
 }
 
+int tcp_skb_shift(struct sk_buff *to, struct sk_buff *from,
+                  int pcount, int shiftlen)
+{
+        /* TCP min gso_size is 8 bytes (TCP_MIN_GSO_SIZE)
+         * Since TCP_SKB_CB(skb)->tcp_gso_segs is 16 bits, we need
+         * to make sure not storing more than 65535 * 8 bytes per skb,
+         * even if current MSS is bigger.
+         */
+        if (unlikely(to->len + shiftlen >= 65535 * TCP_MIN_GSO_SIZE))
+                return 0;
+        if (unlikely(tcp_skb_pcount(to) + pcount > 65535))
+                return 0;
+        return skb_shift(to, from, shiftlen);
+}
+
 /* Try collapsing SACK blocks spanning across multiple skbs to a single
  * skb.
  */
@@ -1473,7 +1488,7 @@ static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
         if (!after(TCP_SKB_CB(skb)->seq + len, tp->snd_una))
                 goto fallback;
 
-        if (!skb_shift(prev, skb, len))
+        if (!tcp_skb_shift(prev, skb, pcount, len))
                 goto fallback;
         if (!tcp_shifted_skb(sk, prev, skb, state, pcount, len, mss, dup_sack))
                 goto out;
@@ -1491,11 +1506,10 @@ static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
                 goto out;
 
         len = skb->len;
-        if (skb_shift(prev, skb, len)) {
-                pcount += tcp_skb_pcount(skb);
-                tcp_shifted_skb(sk, prev, skb, state, tcp_skb_pcount(skb),
+        pcount = tcp_skb_pcount(skb);
+        if (tcp_skb_shift(prev, skb, pcount, len))
+                tcp_shifted_skb(sk, prev, skb, state, pcount,
                                 len, mss, 0);
-        }
 
 out:
         return prev;
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index bc86f9735f45..cfa81190a1b1 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2628,6 +2628,7 @@ static int __net_init tcp_sk_init(struct net *net)
         net->ipv4.sysctl_tcp_ecn_fallback = 1;
 
         net->ipv4.sysctl_tcp_base_mss = TCP_BASE_MSS;
+        net->ipv4.sysctl_tcp_min_snd_mss = TCP_MIN_SND_MSS;
         net->ipv4.sysctl_tcp_probe_threshold = TCP_PROBE_THRESHOLD;
         net->ipv4.sysctl_tcp_probe_interval = TCP_PROBE_INTERVAL;
 
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index f429e856e263..00c01a01b547 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1296,6 +1296,11 @@ int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
         if (nsize < 0)
                 nsize = 0;
 
+        if (unlikely((sk->sk_wmem_queued >> 1) > sk->sk_sndbuf)) {
+                NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPWQUEUETOOBIG);
+                return -ENOMEM;
+        }
+
         if (skb_unclone(skb, gfp))
                 return -ENOMEM;
 
@@ -1454,8 +1459,7 @@ static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu)
         mss_now -= icsk->icsk_ext_hdr_len;
 
         /* Then reserve room for full set of TCP options and 8 bytes of data */
-        if (mss_now < 48)
-                mss_now = 48;
+        mss_now = max(mss_now, sock_net(sk)->ipv4.sysctl_tcp_min_snd_mss);
         return mss_now;
 }
 
@@ -2747,7 +2751,7 @@ static bool tcp_collapse_retrans(struct sock *sk, struct sk_buff *skb)
                 if (next_skb_size <= skb_availroom(skb))
                         skb_copy_bits(next_skb, 0, skb_put(skb, next_skb_size),
                                       next_skb_size);
-                else if (!skb_shift(skb, next_skb, next_skb_size))
+                else if (!tcp_skb_shift(skb, next_skb, 1, next_skb_size))
                         return false;
         }
         tcp_highest_sack_replace(sk, next_skb, skb);
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 5bad937ce779..c801cd37cc2a 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -155,6 +155,7 @@ static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk)
                 mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1;
                 mss = min(net->ipv4.sysctl_tcp_base_mss, mss);
                 mss = max(mss, 68 - tcp_sk(sk)->tcp_header_len);
+                mss = max(mss, net->ipv4.sysctl_tcp_min_snd_mss);
                 icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss);
         }
         tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);