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

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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>
This commit is contained in:
Jakub Sitnicki 2020-03-17 18:04:39 +01:00 committed by David S. Miller
parent 5bb4c45d46
commit d5bee7374b
2 changed files with 6 additions and 5 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

2
net/tls/tls_device.c
View file

@ -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;
}

9
net/tls/tls_main.c
View file

@ -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 &&