tcp: Fix data-races around sysctl knobs related to SYN option.

While reading these knobs, they can be changed concurrently.
Thus, we need to add READ_ONCE() to their readers.

  - tcp_sack
  - tcp_window_scaling
  - tcp_timestamps

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 7c760aa..ddfe920 100644 (file)
--- a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c
+++ b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c
@@ -1236,8 +1236,8 @@ static struct sock *chtls_recv_sock(struct sock *lsk,
        csk->sndbuf = newsk->sk_sndbuf;
        csk->smac_idx = ((struct port_info *)netdev_priv(ndev))->smt_idx;
        RCV_WSCALE(tp) = select_rcv_wscale(tcp_full_space(newsk),
-                                          sock_net(newsk)->
-                                               ipv4.sysctl_tcp_window_scaling,
+                                          READ_ONCE(sock_net(newsk)->
+                                                    ipv4.sysctl_tcp_window_scaling),
                                           tp->window_clamp);
        neigh_release(n);
        inet_inherit_port(&tcp_hashinfo, lsk, newsk);
@@ -1384,7 +1384,7 @@ static void chtls_pass_accept_request(struct sock *sk,
 #endif
        }
        if (req->tcpopt.wsf <= 14 &&
-           sock_net(sk)->ipv4.sysctl_tcp_window_scaling) {
+           READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_window_scaling)) {
                inet_rsk(oreq)->wscale_ok = 1;
                inet_rsk(oreq)->snd_wscale = req->tcpopt.wsf;
        }

diff --git a/net/core/secure_seq.c b/net/core/secure_seq.c
index 5f85e01..b0ff615 100644 (file)
--- a/net/core/secure_seq.c
+++ b/net/core/secure_seq.c
@@ -64,7 +64,7 @@ u32 secure_tcpv6_ts_off(const struct net *net,
                .daddr = *(struct in6_addr *)daddr,
        };
 
-       if (net->ipv4.sysctl_tcp_timestamps != 1)
+       if (READ_ONCE(net->ipv4.sysctl_tcp_timestamps) != 1)
                return 0;
 
        ts_secret_init();
@@ -120,7 +120,7 @@ EXPORT_SYMBOL(secure_ipv6_port_ephemeral);
 #ifdef CONFIG_INET
 u32 secure_tcp_ts_off(const struct net *net, __be32 saddr, __be32 daddr)
 {
-       if (net->ipv4.sysctl_tcp_timestamps != 1)
+       if (READ_ONCE(net->ipv4.sysctl_tcp_timestamps) != 1)
                return 0;
 
        ts_secret_init();

diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 9b234b4..942d2df 100644 (file)
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -247,12 +247,12 @@ bool cookie_timestamp_decode(const struct net *net,
                return true;
        }
 
-       if (!net->ipv4.sysctl_tcp_timestamps)
+       if (!READ_ONCE(net->ipv4.sysctl_tcp_timestamps))
                return false;
 
        tcp_opt->sack_ok = (options & TS_OPT_SACK) ? TCP_SACK_SEEN : 0;
 
-       if (tcp_opt->sack_ok && !net->ipv4.sysctl_tcp_sack)
+       if (tcp_opt->sack_ok && !READ_ONCE(net->ipv4.sysctl_tcp_sack))
                return false;
 
        if ((options & TS_OPT_WSCALE_MASK) == TS_OPT_WSCALE_MASK)
@@ -261,7 +261,7 @@ bool cookie_timestamp_decode(const struct net *net,
        tcp_opt->wscale_ok = 1;
        tcp_opt->snd_wscale = options & TS_OPT_WSCALE_MASK;
 
-       return net->ipv4.sysctl_tcp_window_scaling != 0;
+       return READ_ONCE(net->ipv4.sysctl_tcp_window_scaling) != 0;
 }
 EXPORT_SYMBOL(cookie_timestamp_decode);
 

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index d451248..92626e1 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4060,7 +4060,7 @@ void tcp_parse_options(const struct net *net,
                                break;
                        case TCPOPT_WINDOW:
                                if (opsize == TCPOLEN_WINDOW && th->syn &&
-                                   !estab && net->ipv4.sysctl_tcp_window_scaling) {
+                                   !estab && READ_ONCE(net->ipv4.sysctl_tcp_window_scaling)) {
                                        __u8 snd_wscale = *(__u8 *)ptr;
                                        opt_rx->wscale_ok = 1;
                                        if (snd_wscale > TCP_MAX_WSCALE) {
@@ -4076,7 +4076,7 @@ void tcp_parse_options(const struct net *net,
                        case TCPOPT_TIMESTAMP:
                                if ((opsize == TCPOLEN_TIMESTAMP) &&
                                    ((estab && opt_rx->tstamp_ok) ||
-                                    (!estab && net->ipv4.sysctl_tcp_timestamps))) {
+                                    (!estab && READ_ONCE(net->ipv4.sysctl_tcp_timestamps)))) {
                                        opt_rx->saw_tstamp = 1;
                                        opt_rx->rcv_tsval = get_unaligned_be32(ptr);
                                        opt_rx->rcv_tsecr = get_unaligned_be32(ptr + 4);
@@ -4084,7 +4084,7 @@ void tcp_parse_options(const struct net *net,
                                break;
                        case TCPOPT_SACK_PERM:
                                if (opsize == TCPOLEN_SACK_PERM && th->syn &&
-                                   !estab && net->ipv4.sysctl_tcp_sack) {
+                                   !estab && READ_ONCE(net->ipv4.sysctl_tcp_sack)) {
                                        opt_rx->sack_ok = TCP_SACK_SEEN;
                                        tcp_sack_reset(opt_rx);
                                }

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 3b3552d..38a71e7 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -791,18 +791,18 @@ static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
        opts->mss = tcp_advertise_mss(sk);
        remaining -= TCPOLEN_MSS_ALIGNED;
 
-       if (likely(sock_net(sk)->ipv4.sysctl_tcp_timestamps && !*md5)) {
+       if (likely(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_timestamps) && !*md5)) {
                opts->options |= OPTION_TS;
                opts->tsval = tcp_skb_timestamp(skb) + tp->tsoffset;
                opts->tsecr = tp->rx_opt.ts_recent;
                remaining -= TCPOLEN_TSTAMP_ALIGNED;
        }
-       if (likely(sock_net(sk)->ipv4.sysctl_tcp_window_scaling)) {
+       if (likely(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_window_scaling))) {
                opts->ws = tp->rx_opt.rcv_wscale;
                opts->options |= OPTION_WSCALE;
                remaining -= TCPOLEN_WSCALE_ALIGNED;
        }
-       if (likely(sock_net(sk)->ipv4.sysctl_tcp_sack)) {
+       if (likely(READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_sack))) {
                opts->options |= OPTION_SACK_ADVERTISE;
                if (unlikely(!(OPTION_TS & opts->options)))
                        remaining -= TCPOLEN_SACKPERM_ALIGNED;
@@ -3647,7 +3647,7 @@ static void tcp_connect_init(struct sock *sk)
         * See tcp_input.c:tcp_rcv_state_process case TCP_SYN_SENT.
         */
        tp->tcp_header_len = sizeof(struct tcphdr);
-       if (sock_net(sk)->ipv4.sysctl_tcp_timestamps)
+       if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_timestamps))
                tp->tcp_header_len += TCPOLEN_TSTAMP_ALIGNED;
 
 #ifdef CONFIG_TCP_MD5SIG
@@ -3683,7 +3683,7 @@ static void tcp_connect_init(struct sock *sk)
                                  tp->advmss - (tp->rx_opt.ts_recent_stamp ? tp->tcp_header_len - sizeof(struct tcphdr) : 0),
                                  &tp->rcv_wnd,
                                  &tp->window_clamp,
-                                 sock_net(sk)->ipv4.sysctl_tcp_window_scaling,
+                                 READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_window_scaling),
                                  &rcv_wscale,
                                  rcv_wnd);