Commit d5bee737 authored by Jakub Sitnicki's avatar Jakub Sitnicki Committed by David S. Miller
Browse files

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: default avatarJakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5bb4c45d

net/tls/tls_device.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

		}

net/tls/tls_main.c

+5 −4
Original line number Diff line number Diff line
@@ -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 &&

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