bpf: Add sk_is_inet and IS_ICSK check in tls_sw_has_ctx_tx/rx

As the introduction of the support for vsock and unix sockets in sockmap,
tls_sw_has_ctx_tx/rx cannot presume the socket passed in must be IS_ICSK.
vsock and af_unix sockets have vsock_sock and unix_sock instead of
inet_connection_sock. For these sockets, tls_get_ctx may return an invalid
pointer and cause page fault in function tls_sw_ctx_rx.

BUG: unable to handle page fault for address: 0000000000040030
Workqueue: vsock-loopback vsock_loopback_work
RIP: 0010:sk_psock_strp_data_ready+0x23/0x60
Call Trace:
 ? __die+0x81/0xc3
 ? no_context+0x194/0x350
 ? do_page_fault+0x30/0x110
 ? async_page_fault+0x3e/0x50
 ? sk_psock_strp_data_ready+0x23/0x60
 virtio_transport_recv_pkt+0x750/0x800
 ? update_load_avg+0x7e/0x620
 vsock_loopback_work+0xd0/0x100
 process_one_work+0x1a7/0x360
 worker_thread+0x30/0x390
 ? create_worker+0x1a0/0x1a0
 kthread+0x112/0x130
 ? __kthread_cancel_work+0x40/0x40
 ret_from_fork+0x1f/0x40

v2:
  - Add IS_ICSK check

Fixes: 0608c69 ("bpf: sk_msg, sock{map|hash} redirect through ULP")
Fixes: e91de6a ("bpf: Fix running sk_skb program types with ktls")

Signed-off-by: Zijian Zhang <[email protected]>
Reviewed-by: Cong Wang <[email protected]>
Acked-by: Jakub Kicinski <[email protected]>

include/net/tls.h

@@ -390,17 +390,25 @@ tls_offload_ctx_tx(const struct tls_context *tls_ctx)
 
 static inline bool tls_sw_has_ctx_tx(const struct sock *sk)
 {
-	struct tls_context *ctx = tls_get_ctx(sk);
+	struct tls_context *ctx;
+
+	if (!sk_is_inet(sk) || !inet_test_bit(IS_ICSK, sk))
+		return false;
 
+	ctx = tls_get_ctx(sk);
 	if (!ctx)
 		return false;
 	return !!tls_sw_ctx_tx(ctx);
 }
 
 static inline bool tls_sw_has_ctx_rx(const struct sock *sk)
 {
-	struct tls_context *ctx = tls_get_ctx(sk);
+	struct tls_context *ctx;
+
+	if (!sk_is_inet(sk) || !inet_test_bit(IS_ICSK, sk))
+		return false;
 
+	ctx = tls_get_ctx(sk);
 	if (!ctx)
 		return false;
 	return !!tls_sw_ctx_rx(ctx);