mptcp: fix lockless access in subflow ULP diag

commit b8adb69a7d29c2d33eb327bca66476fb6066516b upstream.

Since the introduction of the subflow ULP diag interface, the
dump callback accessed all the subflow data with lockless.

We need either to annotate all the read and write operation accordingly,
or acquire the subflow socket lock. Let's do latter, even if slower, to
avoid a diffstat havoc.

Fixes: 5147dfb50832 ("mptcp: allow dumping subflow context to userspace")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 4c838f7290dd97ab0ea810732f7841437148ab8b..8ea1fba84eff96a3566a658f61fce68f39a050d4 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2290,7 +2290,7 @@ struct tcp_ulp_ops {
        /* cleanup ulp */
        void (*release)(struct sock *sk);
        /* diagnostic */
-       int (*get_info)(const struct sock *sk, struct sk_buff *skb);
+       int (*get_info)(struct sock *sk, struct sk_buff *skb);
        size_t (*get_info_size)(const struct sock *sk);
        /* clone ulp */
        void (*clone)(const struct request_sock *req, struct sock *newsk,

diff --git a/net/mptcp/diag.c b/net/mptcp/diag.c
index a536586742f28c1ddd54c79e62eb56fea267a8fa..e57c5f47f0351a37c9e83e111b2ee5308c141ff6 100644 (file)
--- a/net/mptcp/diag.c
+++ b/net/mptcp/diag.c
@@ -13,17 +13,19 @@
 #include <uapi/linux/mptcp.h>
 #include "protocol.h"
 
-static int subflow_get_info(const struct sock *sk, struct sk_buff *skb)
+static int subflow_get_info(struct sock *sk, struct sk_buff *skb)
 {
        struct mptcp_subflow_context *sf;
        struct nlattr *start;
        u32 flags = 0;
+       bool slow;
        int err;
 
        start = nla_nest_start_noflag(skb, INET_ULP_INFO_MPTCP);
        if (!start)
                return -EMSGSIZE;
 
+       slow = lock_sock_fast(sk);
        rcu_read_lock();
        sf = rcu_dereference(inet_csk(sk)->icsk_ulp_data);
        if (!sf) {
@@ -69,11 +71,13 @@ static int subflow_get_info(const struct sock *sk, struct sk_buff *skb)
        }
 
        rcu_read_unlock();
+       unlock_sock_fast(sk, slow);
        nla_nest_end(skb, start);
        return 0;
 
 nla_failure:
        rcu_read_unlock();
+       unlock_sock_fast(sk, slow);
        nla_nest_cancel(skb, start);
        return err;
 }

diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index 80b42a3e78830b88f05239c48ab54765b69db4a6..6b7189a520af77246d081556ea884817e3e8b116 100644 (file)
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -1098,7 +1098,7 @@ static u16 tls_user_config(struct tls_context *ctx, bool tx)
        return 0;
 }
 
-static int tls_get_info(const struct sock *sk, struct sk_buff *skb)
+static int tls_get_info(struct sock *sk, struct sk_buff *skb)
 {
        u16 version, cipher_type;
        struct tls_context *ctx;