mptcp: fix lockless access in subflow ULP diag

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>

diff --git a/include/net/tcp.h b/include/net/tcp.h
index dd78a11810310e84ef1c1ed8c3e0e274ddd77d7f..f6eba9652d010fbc8482bfd3c99377d631686324 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2506,7 +2506,7 @@ 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 1c2c6800949dd4c2800f76326b7500f9743c4720..b4674f03d71a9fb9a5526555d7aca9b9cc5e665c 100644 (file)
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -1003,7 +1003,7 @@ 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;