tcp: Fix data-races around sysctl_tcp_ecn.

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>

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 4af5561..7c760aa 100644 (file)
--- 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 f33c31d..b387c48 100644 (file)
--- 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 66159d4..5e308c1 100644 (file)
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -676,6 +676,8 @@ 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 2e2a9ec..3ec4edc 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6729,7 +6729,7 @@ 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 1c05443..3dc1755 100644 (file)
--- 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) {