skmsg: Teach sk_psock_verdict_apply() to return errors

mainline inclusion
from mainline-v5.14-rc1
commit 1581a6c1
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4VIOZ?from=project-issue

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1581a6c1c3291a8320b080f4411345f60229976d

--------------------------------

Currently sk_psock_verdict_apply() is void, but it handles some
error conditions too. Its caller is impossible to learn whether
it succeeds or fails, especially sk_psock_verdict_recv().

Make it return int to indicate error cases and propagate errors
to callers properly.

Fixes: ef565928 ("bpf, sockmap: Allow skipping sk_skb parser program")
Signed-off-by: NCong Wang <cong.wang@bytedance.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Acked-by: NJakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20210615021342.7416-7-xiyou.wangcong@gmail.com
Conflicts:
	net/core/skmsg.c
Signed-off-by: NZiyang Xuan <william.xuanziyang@huawei.com>
Reviewed-by: NYue Haibing <yuehaibing@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

net/core/skmsg.c

@@ -765,7 +765,7 @@ static struct sk_psock *sk_psock_from_strp(struct strparser *strp)
 	return container_of(parser, struct sk_psock, parser);
 }
 
-static void sk_psock_skb_redirect(struct sk_buff *skb)
+static int sk_psock_skb_redirect(struct sk_buff *skb)
 {
 	struct sk_psock *psock_other;
 	struct sock *sk_other;
@@ -776,7 +776,7 @@ static void sk_psock_skb_redirect(struct sk_buff *skb)
 	 */
 	if (unlikely(!sk_other)) {
 		kfree_skb(skb);
-		return;
+		return -EIO;
 	}
 	psock_other = sk_psock(sk_other);
 	/* This error indicates the socket is being torn down or had another
@@ -786,11 +786,12 @@ static void sk_psock_skb_redirect(struct sk_buff *skb)
 	if (!psock_other || sock_flag(sk_other, SOCK_DEAD) ||
 	    !sk_psock_test_state(psock_other, SK_PSOCK_TX_ENABLED)) {
 		kfree_skb(skb);
-		return;
+		return -EIO;
 	}
 
 	skb_queue_tail(&psock_other->ingress_skb, skb);
 	schedule_work(&psock_other->work);
+	return 0;
 }
 
 static void sk_psock_tls_verdict_apply(struct sk_buff *skb, struct sock *sk, int verdict)
@@ -826,15 +827,16 @@ int sk_psock_tls_strp_read(struct sk_psock *psock, struct sk_buff *skb)
 }
 EXPORT_SYMBOL_GPL(sk_psock_tls_strp_read);
 
-static void sk_psock_verdict_apply(struct sk_psock *psock,
-				   struct sk_buff *skb, int verdict)
+static int sk_psock_verdict_apply(struct sk_psock *psock, struct sk_buff *skb,
+				  int verdict)
 {
 	struct tcp_skb_cb *tcp;
 	struct sock *sk_other;
-	int err = -EIO;
+	int err = 0;
 
 	switch (verdict) {
 	case __SK_PASS:
+		err = -EIO;
 		sk_other = psock->sk;
 		if (sock_flag(sk_other, SOCK_DEAD) ||
 		    !sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED)) {
@@ -859,13 +861,15 @@ static void sk_psock_verdict_apply(struct sk_psock *psock,
 		}
 		break;
 	case __SK_REDIRECT:
-		sk_psock_skb_redirect(skb);
+		err = sk_psock_skb_redirect(skb);
 		break;
 	case __SK_DROP:
 	default:
 out_free:
 		kfree_skb(skb);
 	}
+
+	return err;
 }
 
 static void sk_psock_strp_read(struct strparser *strp, struct sk_buff *skb)
@@ -967,7 +971,8 @@ static int sk_psock_verdict_recv(read_descriptor_t *desc, struct sk_buff *skb,
 		ret = sk_psock_map_verd(ret, tcp_skb_bpf_redirect_fetch(skb));
 		skb->sk = NULL;
 	}
-	sk_psock_verdict_apply(psock, skb, ret);
+	if (sk_psock_verdict_apply(psock, skb, ret) < 0)
+		len = 0;
 out:
 	rcu_read_unlock();
 	return len;