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Date: Mon, 17 Jun 2019 20:08:20 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>,
torvalds@...ux-foundation.org, stable@...r.kernel.org
Cc: lwn@....net, Jiri Slaby <jslaby@...e.cz>
Subject: Re: Linux 4.4.182
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 709d24b4b533..21ad4f3cece8 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -220,6 +220,14 @@ tcp_base_mss - INTEGER
Path MTU discovery (MTU probing). If MTU probing is enabled,
this is the initial MSS used by the connection.
+tcp_min_snd_mss - INTEGER
+ TCP SYN and SYNACK messages usually advertise an ADVMSS option,
+ as described in RFC 1122 and RFC 6691.
+ If this ADVMSS option is smaller than tcp_min_snd_mss,
+ it is silently capped to tcp_min_snd_mss.
+
+ Default : 48 (at least 8 bytes of payload per segment)
+
tcp_congestion_control - STRING
Set the congestion control algorithm to be used for new
connections. The algorithm "reno" is always available, but
diff --git a/Makefile b/Makefile
index b33f3ecf84fc..fcfede5e39de 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
VERSION = 4
PATCHLEVEL = 4
-SUBLEVEL = 181
+SUBLEVEL = 182
EXTRAVERSION =
NAME = Blurry Fish Butt
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 747404dbe506..085da1707cea 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -419,4 +419,7 @@ static inline void tcp_saved_syn_free(struct tcp_sock *tp)
tp->saved_syn = NULL;
}
+int tcp_skb_shift(struct sk_buff *to, struct sk_buff *from, int pcount,
+ int shiftlen);
+
#endif /* _LINUX_TCP_H */
diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h
index c68926b4899c..61c38f87ea07 100644
--- a/include/net/netns/ipv4.h
+++ b/include/net/netns/ipv4.h
@@ -88,6 +88,7 @@ struct netns_ipv4 {
int sysctl_tcp_fwmark_accept;
int sysctl_tcp_mtu_probing;
int sysctl_tcp_base_mss;
+ int sysctl_tcp_min_snd_mss;
int sysctl_tcp_probe_threshold;
u32 sysctl_tcp_probe_interval;
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 14ec97309581..bf8a0dae977a 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -54,6 +54,8 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
#define MAX_TCP_HEADER (128 + MAX_HEADER)
#define MAX_TCP_OPTION_SPACE 40
+#define TCP_MIN_SND_MSS 48
+#define TCP_MIN_GSO_SIZE (TCP_MIN_SND_MSS - MAX_TCP_OPTION_SPACE)
/*
* Never offer a window over 32767 without using window scaling. Some
diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h
index 9de808ebce05..422183f396d5 100644
--- a/include/uapi/linux/snmp.h
+++ b/include/uapi/linux/snmp.h
@@ -281,6 +281,7 @@ enum
LINUX_MIB_TCPKEEPALIVE, /* TCPKeepAlive */
LINUX_MIB_TCPMTUPFAIL, /* TCPMTUPFail */
LINUX_MIB_TCPMTUPSUCCESS, /* TCPMTUPSuccess */
+ LINUX_MIB_TCPWQUEUETOOBIG, /* TCPWqueueTooBig */
__LINUX_MIB_MAX
};
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index b001ad668108..555586fc7840 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -303,6 +303,7 @@ static const struct snmp_mib snmp4_net_list[] = {
SNMP_MIB_ITEM("TCPKeepAlive", LINUX_MIB_TCPKEEPALIVE),
SNMP_MIB_ITEM("TCPMTUPFail", LINUX_MIB_TCPMTUPFAIL),
SNMP_MIB_ITEM("TCPMTUPSuccess", LINUX_MIB_TCPMTUPSUCCESS),
+ 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 167ca0fddf9e..6413e36d639d 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -36,6 +36,8 @@ 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_ttl_min = 1;
static int ip_ttl_max = 255;
static int tcp_syn_retries_min = 1;
@@ -941,6 +943,15 @@ static struct ctl_table ipv4_net_table[] = {
.mode = 0644,
.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,
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index f3a4d2dcbf7a..303be2b76855 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3144,6 +3144,7 @@ void __init tcp_init(void)
int max_rshare, max_wshare, cnt;
unsigned int i;
+ BUILD_BUG_ON(TCP_MIN_SND_MSS <= MAX_TCP_OPTION_SPACE);
sock_skb_cb_check_size(sizeof(struct tcp_skb_cb));
percpu_counter_init(&tcp_sockets_allocated, 0, GFP_KERNEL);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 44a3aa7a41e2..30c5500b0899 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1275,7 +1275,7 @@ static bool tcp_shifted_skb(struct sock *sk, struct sk_buff *skb,
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,
@@ -1337,6 +1337,21 @@ 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.
*/
@@ -1348,6 +1363,7 @@ static struct sk_buff *tcp_shift_skb_data(struct sock *sk, struct sk_buff *skb,
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *prev;
int mss;
+ int next_pcount;
int pcount = 0;
int len;
int in_sack;
@@ -1442,7 +1458,7 @@ 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, skb, state, pcount, len, mss, dup_sack))
goto out;
@@ -1461,11 +1477,11 @@ 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, skb, state, tcp_skb_pcount(skb), len, mss, 0);
+ next_pcount = tcp_skb_pcount(skb);
+ if (tcp_skb_shift(prev, skb, next_pcount, len)) {
+ pcount += next_pcount;
+ tcp_shifted_skb(sk, skb, state, next_pcount, len, mss, 0);
}
-
out:
state->fack_count += pcount;
return prev;
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index b3d6b8e77300..744afb4fbf84 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2419,6 +2419,7 @@ 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 b55b8954dae5..bed83990847a 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1161,6 +1161,11 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len,
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;
@@ -1327,8 +1332,7 @@ 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;
}
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 35f638cfc675..61359944acc7 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -132,6 +132,7 @@ 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 - tp->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);
}
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