[PATCH 5.10 068/105] tcp: Fix data-races around sysctl knobs related to SYN option.

Greg Kroah-Hartman
2022-07-27T16:54:07Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 3666f666e99600518ab20982af04a078bbdad277 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../ethernet/chelsio/inline_crypto/chtls/chtls_cm.c | 6 +++---
net/core/secure_seq.c | 4 ++--
net/ipv4/syncookies.c | 6 +++---
net/ipv4/tcp_input.c | 6 +++---
net/ipv4/tcp_output.c | 10 +++++-----
5 files changed, 16 insertions(+), 16 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 51e071c20e39..cd6e016e6210 100644
--- a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c
+++ b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c
@@ -1235,8 +1235,8 @@ 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);
@@ -1383,7 +1383,7 @@ 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 7131cd1fb2ad..189eea1372d5 100644
--- 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 b52cc46bdadd..41afc9155f31 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -249,12 +249,12 @@ 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)
@@ -263,7 +263,7 @@ 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 5cbabe0e42c9..8ac3acde08b4 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4007,7 +4007,7 @@ 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) {
@@ -4023,7 +4023,7 @@ 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);
@@ -4031,7 +4031,7 @@ 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 e7348e70e6e3..772dd6241b70 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -789,18 +789,18 @@ 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;
@@ -3648,7 +3648,7 @@ 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
@@ -3684,7 +3684,7 @@ 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);

--
2.35.1