[PATCH 5.18 120/231] tcp: Fix data-races around sysctl_tcp_ecn.

Greg Kroah-Hartman
2022-07-19T13:04:01Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 4785a66702f086cf2ea84bdbe6ec921f274bd9f2 ]

While reading sysctl_tcp_ecn, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c | 2 +-
net/ipv4/syncookies.c | 2 +-
net/ipv4/sysctl_net_ipv4.c | 2 ++
net/ipv4/tcp_input.c | 2 +-
net/ipv4/tcp_output.c | 2 +-
5 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c
index 4af5561cbfc5..7c760aa65540 100644
--- a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c
+++ b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c
@@ -1392,7 +1392,7 @@ static void chtls_pass_accept_request(struct sock *sk,
th_ecn = tcph->ece && tcph->cwr;
if (th_ecn) {
ect = !INET_ECN_is_not_ect(ip_dsfield);
- ecn_ok = sock_net(sk)->ipv4.sysctl_tcp_ecn;
+ ecn_ok = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn);
if ((!ect && ecn_ok) || tcp_ca_needs_ecn(sk))
inet_rsk(oreq)->ecn_ok = 1;
}
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index f33c31dd7366..b387c4835155 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -273,7 +273,7 @@ bool cookie_ecn_ok(const struct tcp_options_received *tcp_opt,
if (!ecn_ok)
return false;

- if (net->ipv4.sysctl_tcp_ecn)
+ if (READ_ONCE(net->ipv4.sysctl_tcp_ecn))
return true;

return dst_feature(dst, RTAX_FEATURE_ECN);
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 33e65e79e46e..11add5214713 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -680,6 +680,8 @@ static struct ctl_table ipv4_net_table[] = {
.maxlen = sizeof(u8),
.mode = 0644,
.proc_handler = proc_dou8vec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_TWO,
},
{
.procname = "tcp_ecn_fallback",
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 6b8fcf79688b..2d71bcfcc759 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6712,7 +6712,7 @@ static void tcp_ecn_create_request(struct request_sock *req,

ect = !INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield);
ecn_ok_dst = dst_feature(dst, DST_FEATURE_ECN_MASK);
- ecn_ok = net->ipv4.sysctl_tcp_ecn || ecn_ok_dst;
+ ecn_ok = READ_ONCE(net->ipv4.sysctl_tcp_ecn) || ecn_ok_dst;

if (((!ect || th->res1) && ecn_ok) || tcp_ca_needs_ecn(listen_sk) ||
(ecn_ok_dst & DST_FEATURE_ECN_CA) ||
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 6b00c17c72aa..9eefe7f6370f 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -324,7 +324,7 @@ static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);
bool bpf_needs_ecn = tcp_bpf_ca_needs_ecn(sk);
- bool use_ecn = sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 ||
+ bool use_ecn = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn) == 1 ||
tcp_ca_needs_ecn(sk) || bpf_needs_ecn;

if (!use_ecn) {
--
2.35.1