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 fe9fc568b2888b679e2b2067b93b256c88d064d5..08923ed4278f09b11ea57f6b21b9868212944fe2 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2233,7 +2233,7 @@ 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 20b8ba4d1dfc4fe0088ef406b6ea88f79fc480ec..79ea1ab34570ff0db7aabcb26321ef796fc9f339 100644 (file)
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -805,7 +805,7 @@ static void tls_update(struct sock *sk, struct proto *p,
        }
 }
 
-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;