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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Eric Dumazet <edumazet@google.com>,
        Thomas Bartschies <Thomas.Bartschies@cvk.de>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 5.3 124/140] net: ensure correct skb->tstamp in various fragmenters
Date:   Fri,  8 Nov 2019 19:50:52 +0100
Message-Id: <20191108174912.529483559@linuxfoundation.org>
In-Reply-To: <20191108174900.189064908@linuxfoundation.org>
References: <20191108174900.189064908@linuxfoundation.org>
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From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 9669fffc1415bb0c30e5d2ec98a8e1c3a418cb9c ]

Thomas found that some forwarded packets would be stuck
in FQ packet scheduler because their skb->tstamp contained
timestamps far in the future.

We thought we addressed this point in commit 8203e2d844d3
("net: clear skb->tstamp in forwarding paths") but there
is still an issue when/if a packet needs to be fragmented.

In order to meet EDT requirements, we have to make sure all
fragments get the original skb->tstamp.

Note that this original skb->tstamp should be zero in
forwarding path, but might have a non zero value in
output path if user decided so.

Fixes: fb420d5d91c1 ("tcp/fq: move back to CLOCK_MONOTONIC")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Thomas Bartschies <Thomas.Bartschies@cvk.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/bridge/netfilter/nf_conntrack_bridge.c |    3 +++
 net/ipv4/ip_output.c                       |    3 +++
 net/ipv6/ip6_output.c                      |    3 +++
 net/ipv6/netfilter.c                       |    3 +++
 4 files changed, 12 insertions(+)

--- a/net/bridge/netfilter/nf_conntrack_bridge.c
+++ b/net/bridge/netfilter/nf_conntrack_bridge.c
@@ -34,6 +34,7 @@ static int nf_br_ip_fragment(struct net
 {
 	int frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size;
 	unsigned int hlen, ll_rs, mtu;
+	ktime_t tstamp = skb->tstamp;
 	struct ip_frag_state state;
 	struct iphdr *iph;
 	int err;
@@ -81,6 +82,7 @@ static int nf_br_ip_fragment(struct net
 			if (iter.frag)
 				ip_fraglist_prepare(skb, &iter);
 
+			skb->tstamp = tstamp;
 			err = output(net, sk, data, skb);
 			if (err || !iter.frag)
 				break;
@@ -105,6 +107,7 @@ slow_path:
 			goto blackhole;
 		}
 
+		skb2->tstamp = tstamp;
 		err = output(net, sk, data, skb2);
 		if (err)
 			goto blackhole;
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -771,6 +771,7 @@ int ip_do_fragment(struct net *net, stru
 	struct rtable *rt = skb_rtable(skb);
 	unsigned int mtu, hlen, ll_rs;
 	struct ip_fraglist_iter iter;
+	ktime_t tstamp = skb->tstamp;
 	struct ip_frag_state state;
 	int err = 0;
 
@@ -846,6 +847,7 @@ int ip_do_fragment(struct net *net, stru
 				ip_fraglist_prepare(skb, &iter);
 			}
 
+			skb->tstamp = tstamp;
 			err = output(net, sk, skb);
 
 			if (!err)
@@ -901,6 +903,7 @@ slow_path:
 		/*
 		 *	Put this fragment into the sending queue.
 		 */
+		skb2->tstamp = tstamp;
 		err = output(net, sk, skb2);
 		if (err)
 			goto fail;
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -768,6 +768,7 @@ int ip6_fragment(struct net *net, struct
 				inet6_sk(skb->sk) : NULL;
 	struct ip6_frag_state state;
 	unsigned int mtu, hlen, nexthdr_offset;
+	ktime_t tstamp = skb->tstamp;
 	int hroom, err = 0;
 	__be32 frag_id;
 	u8 *prevhdr, nexthdr = 0;
@@ -855,6 +856,7 @@ int ip6_fragment(struct net *net, struct
 			if (iter.frag)
 				ip6_fraglist_prepare(skb, &iter);
 
+			skb->tstamp = tstamp;
 			err = output(net, sk, skb);
 			if (!err)
 				IP6_INC_STATS(net, ip6_dst_idev(&rt->dst),
@@ -913,6 +915,7 @@ slow_path:
 		/*
 		 *	Put this fragment into the sending queue.
 		 */
+		frag->tstamp = tstamp;
 		err = output(net, sk, frag);
 		if (err)
 			goto fail;
--- a/net/ipv6/netfilter.c
+++ b/net/ipv6/netfilter.c
@@ -119,6 +119,7 @@ int br_ip6_fragment(struct net *net, str
 				  struct sk_buff *))
 {
 	int frag_max_size = BR_INPUT_SKB_CB(skb)->frag_max_size;
+	ktime_t tstamp = skb->tstamp;
 	struct ip6_frag_state state;
 	u8 *prevhdr, nexthdr = 0;
 	unsigned int mtu, hlen;
@@ -183,6 +184,7 @@ int br_ip6_fragment(struct net *net, str
 			if (iter.frag)
 				ip6_fraglist_prepare(skb, &iter);
 
+			skb->tstamp = tstamp;
 			err = output(net, sk, data, skb);
 			if (err || !iter.frag)
 				break;
@@ -215,6 +217,7 @@ slow_path:
 			goto blackhole;
 		}
 
+		skb2->tstamp = tstamp;
 		err = output(net, sk, data, skb2);
 		if (err)
 			goto blackhole;