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Date: Tue, 29 Dec 2020 05:59:20 +0800
From: Pengcheng Yang <yangpc@...gsu.com>
To: edumazet@...gle.com, davem@...emloft.net
Cc: netdev@...r.kernel.org, Pengcheng Yang <yangpc@...gsu.com>
Subject: [PATCH net] tcp: fix TCP_SKB_CB(skb)->tcp_tw_isn not being used
TCP_SKB_CB(skb)->tcp_tw_isn contains an ISN, chosen by
tcp_timewait_state_process() , when SYN is received in TIMEWAIT state.
But tcp_tw_isn is not used because it is overwritten by
tcp_v4_restore_cb() after commit eeea10b83a13 ("tcp: add
tcp_v4_fill_cb()/tcp_v4_restore_cb()").
To fix this case, we record tcp_tw_isn before tcp_v4_restore_cb() and
then set it in tcp_v4_fill_cb(). V6 does the same.
Fixes: eeea10b83a13 ("tcp: add tcp_v4_fill_cb()/tcp_v4_restore_cb()")
Reported-by: chenc <chenc9@...gsu.com>
Signed-off-by: Pengcheng Yang <yangpc@...gsu.com>
---
net/ipv4/tcp_ipv4.c | 14 ++++++++------
net/ipv6/tcp_ipv6.c | 14 ++++++++------
2 files changed, 16 insertions(+), 12 deletions(-)
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 58207c7..c8cceaa 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1892,7 +1892,7 @@ static void tcp_v4_restore_cb(struct sk_buff *skb)
}
static void tcp_v4_fill_cb(struct sk_buff *skb, const struct iphdr *iph,
- const struct tcphdr *th)
+ const struct tcphdr *th, __u32 isn)
{
/* This is tricky : We move IPCB at its correct location into TCP_SKB_CB()
* barrier() makes sure compiler wont play fool^Waliasing games.
@@ -1906,7 +1906,7 @@ static void tcp_v4_fill_cb(struct sk_buff *skb, const struct iphdr *iph,
skb->len - th->doff * 4);
TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th);
- TCP_SKB_CB(skb)->tcp_tw_isn = 0;
+ TCP_SKB_CB(skb)->tcp_tw_isn = isn;
TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph);
TCP_SKB_CB(skb)->sacked = 0;
TCP_SKB_CB(skb)->has_rxtstamp =
@@ -1927,6 +1927,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
const struct tcphdr *th;
bool refcounted;
struct sock *sk;
+ __u32 isn = 0;
int ret;
if (skb->pkt_type != PACKET_HOST)
@@ -1993,7 +1994,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
if (!tcp_filter(sk, skb)) {
th = (const struct tcphdr *)skb->data;
iph = ip_hdr(skb);
- tcp_v4_fill_cb(skb, iph, th);
+ tcp_v4_fill_cb(skb, iph, th, isn);
nsk = tcp_check_req(sk, skb, req, false, &req_stolen);
}
if (!nsk) {
@@ -2038,7 +2039,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
goto discard_and_relse;
th = (const struct tcphdr *)skb->data;
iph = ip_hdr(skb);
- tcp_v4_fill_cb(skb, iph, th);
+ tcp_v4_fill_cb(skb, iph, th, isn);
skb->dev = NULL;
@@ -2075,7 +2076,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
goto discard_it;
- tcp_v4_fill_cb(skb, iph, th);
+ tcp_v4_fill_cb(skb, iph, th, isn);
if (tcp_checksum_complete(skb)) {
csum_error:
@@ -2103,7 +2104,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
goto discard_it;
}
- tcp_v4_fill_cb(skb, iph, th);
+ tcp_v4_fill_cb(skb, iph, th, isn);
if (tcp_checksum_complete(skb)) {
inet_twsk_put(inet_twsk(sk));
@@ -2121,6 +2122,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
if (sk2) {
inet_twsk_deschedule_put(inet_twsk(sk));
sk = sk2;
+ isn = TCP_SKB_CB(skb)->tcp_tw_isn;
tcp_v4_restore_cb(skb);
refcounted = false;
goto process;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 0e1509b..a2ff19d 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1557,7 +1557,7 @@ static int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
}
static void tcp_v6_fill_cb(struct sk_buff *skb, const struct ipv6hdr *hdr,
- const struct tcphdr *th)
+ const struct tcphdr *th, __u32 isn)
{
/* This is tricky: we move IP6CB at its correct location into
* TCP_SKB_CB(). It must be done after xfrm6_policy_check(), because
@@ -1573,7 +1573,7 @@ static void tcp_v6_fill_cb(struct sk_buff *skb, const struct ipv6hdr *hdr,
skb->len - th->doff*4);
TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th);
- TCP_SKB_CB(skb)->tcp_tw_isn = 0;
+ TCP_SKB_CB(skb)->tcp_tw_isn = isn;
TCP_SKB_CB(skb)->ip_dsfield = ipv6_get_dsfield(hdr);
TCP_SKB_CB(skb)->sacked = 0;
TCP_SKB_CB(skb)->has_rxtstamp =
@@ -1589,6 +1589,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
const struct ipv6hdr *hdr;
bool refcounted;
struct sock *sk;
+ __u32 isn = 0;
int ret;
struct net *net = dev_net(skb->dev);
@@ -1652,7 +1653,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
if (!tcp_filter(sk, skb)) {
th = (const struct tcphdr *)skb->data;
hdr = ipv6_hdr(skb);
- tcp_v6_fill_cb(skb, hdr, th);
+ tcp_v6_fill_cb(skb, hdr, th, isn);
nsk = tcp_check_req(sk, skb, req, false, &req_stolen);
}
if (!nsk) {
@@ -1695,7 +1696,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
goto discard_and_relse;
th = (const struct tcphdr *)skb->data;
hdr = ipv6_hdr(skb);
- tcp_v6_fill_cb(skb, hdr, th);
+ tcp_v6_fill_cb(skb, hdr, th, isn);
skb->dev = NULL;
@@ -1730,7 +1731,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
goto discard_it;
- tcp_v6_fill_cb(skb, hdr, th);
+ tcp_v6_fill_cb(skb, hdr, th, isn);
if (tcp_checksum_complete(skb)) {
csum_error:
@@ -1757,7 +1758,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
goto discard_it;
}
- tcp_v6_fill_cb(skb, hdr, th);
+ tcp_v6_fill_cb(skb, hdr, th, isn);
if (tcp_checksum_complete(skb)) {
inet_twsk_put(inet_twsk(sk));
@@ -1780,6 +1781,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
struct inet_timewait_sock *tw = inet_twsk(sk);
inet_twsk_deschedule_put(tw);
sk = sk2;
+ isn = TCP_SKB_CB(skb)->tcp_tw_isn;
tcp_v6_restore_cb(skb);
refcounted = false;
goto process;
--
1.8.3.1
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