net/tls: Annotate access to sk_prot with READ_ONCE/WRITE_ONCE

sockmap performs lockless writes to sk->sk_prot on the following paths:

tcp_bpf_{recvmsg|sendmsg} / sock_map_unref
  sk_psock_put
    sk_psock_drop
      sk_psock_restore_proto
        WRITE_ONCE(sk->sk_prot, proto)

To prevent load/store tearing [1], and to make tooling aware of intentional
shared access [2], we need to annotate other sites that access sk_prot with
READ_ONCE/WRITE_ONCE macros.

Change done with Coccinelle with following semantic patch:

@@
expression E;
identifier I;
struct sock *sk;
identifier sk_prot =~ "^sk_prot$";
@@
(
 E =
-sk->sk_prot
+READ_ONCE(sk->sk_prot)
|
-sk->sk_prot = E
+WRITE_ONCE(sk->sk_prot, E)
|
-sk->sk_prot
+READ_ONCE(sk->sk_prot)
 ->I
)

Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/tls/tls_device.c b/net/tls/tls_device.c
index 1c5574e..a562eba 100644 (file)
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -366,7 +366,7 @@ static int tls_do_allocation(struct sock *sk,
        if (!offload_ctx->open_record) {
                if (unlikely(!skb_page_frag_refill(prepend_size, pfrag,
                                                   sk->sk_allocation))) {
-                       sk->sk_prot->enter_memory_pressure(sk);
+                       READ_ONCE(sk->sk_prot)->enter_memory_pressure(sk);
                        sk_stream_moderate_sndbuf(sk);
                        return -ENOMEM;
                }

diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
index e7de030..156efce 100644 (file)
--- a/net/tls/tls_main.c
+++ b/net/tls/tls_main.c
@@ -69,7 +69,8 @@ void update_sk_prot(struct sock *sk, struct tls_context *ctx)
 {
        int ip_ver = sk->sk_family == AF_INET6 ? TLSV6 : TLSV4;
 
-       sk->sk_prot = &tls_prots[ip_ver][ctx->tx_conf][ctx->rx_conf];
+       WRITE_ONCE(sk->sk_prot,
+                  &tls_prots[ip_ver][ctx->tx_conf][ctx->rx_conf]);
 }
 
 int wait_on_pending_writer(struct sock *sk, long *timeo)
@@ -312,7 +313,7 @@ static void tls_sk_proto_close(struct sock *sk, long timeout)
        write_lock_bh(&sk->sk_callback_lock);
        if (free_ctx)
                rcu_assign_pointer(icsk->icsk_ulp_data, NULL);
-       sk->sk_prot = ctx->sk_proto;
+       WRITE_ONCE(sk->sk_prot, ctx->sk_proto);
        if (sk->sk_write_space == tls_write_space)
                sk->sk_write_space = ctx->sk_write_space;
        write_unlock_bh(&sk->sk_callback_lock);
@@ -621,14 +622,14 @@ struct tls_context *tls_ctx_create(struct sock *sk)
 
        mutex_init(&ctx->tx_lock);
        rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
-       ctx->sk_proto = sk->sk_prot;
+       ctx->sk_proto = READ_ONCE(sk->sk_prot);
        return ctx;
 }
 
 static void tls_build_proto(struct sock *sk)
 {
        int ip_ver = sk->sk_family == AF_INET6 ? TLSV6 : TLSV4;
-       const struct proto *prot = sk->sk_prot;
+       const struct proto *prot = READ_ONCE(sk->sk_prot);
 
        /* Build IPv6 TLS whenever the address of tcpv6 _prot changes */
        if (ip_ver == TLSV6 &&