netdev - [PATCH v1 net-next 06/15] af_unix: Set error only when needed in unix_dgram

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Message-ID: <20241206052607.1197-7-kuniyu@amazon.com>
Date: Fri, 6 Dec 2024 14:25:58 +0900
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>
CC: Kuniyuki Iwashima <kuniyu@...zon.com>, Kuniyuki Iwashima
	<kuni1840@...il.com>, <netdev@...r.kernel.org>
Subject: [PATCH v1 net-next 06/15] af_unix: Set error only when needed in unix_dgram_sendmsg().

We will introduce skb drop reason for AF_UNIX, then we need to
set an errno and a drop reason for each path.

Let's set an error only when it's needed in unix_dgram_sendmsg().

Then, we need not (re)set 0 to err.

Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
 net/unix/af_unix.c | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 7e6241ba7604..e439829efc56 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1978,9 +1978,10 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 
 	wait_for_unix_gc(scm.fp);
 
-	err = -EOPNOTSUPP;
-	if (msg->msg_flags&MSG_OOB)
+	if (msg->msg_flags & MSG_OOB) {
+		err = -EOPNOTSUPP;
 		goto out;
+	}
 
 	if (msg->msg_namelen) {
 		err = unix_validate_addr(sunaddr, msg->msg_namelen);
@@ -1995,10 +1996,11 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 			goto out;
 	} else {
 		sunaddr = NULL;
-		err = -ENOTCONN;
 		other = unix_peer_get(sk);
-		if (!other)
+		if (!other) {
+			err = -ENOTCONN;
 			goto out;
+		}
 	}
 
 	if ((test_bit(SOCK_PASSCRED, &sock->flags) ||
@@ -2009,9 +2011,10 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 			goto out;
 	}
 
-	err = -EMSGSIZE;
-	if (len > READ_ONCE(sk->sk_sndbuf) - 32)
+	if (len > READ_ONCE(sk->sk_sndbuf) - 32) {
+		err = -EMSGSIZE;
 		goto out;
+	}
 
 	if (len > SKB_MAX_ALLOC) {
 		data_len = min_t(size_t,
@@ -2043,9 +2046,10 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 
 restart:
 	if (!other) {
-		err = -ECONNRESET;
-		if (sunaddr == NULL)
+		if (!sunaddr) {
+			err = -ECONNRESET;
 			goto out_free;
+		}
 
 		other = unix_find_other(sock_net(sk), sunaddr, msg->msg_namelen,
 					sk->sk_type);
@@ -2065,9 +2069,11 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 	sk_locked = 0;
 	unix_state_lock(other);
 restart_locked:
-	err = -EPERM;
-	if (!unix_may_send(sk, other))
+
+	if (!unix_may_send(sk, other)) {
+		err = -EPERM;
 		goto out_unlock;
+	}
 
 	if (unlikely(sock_flag(other, SOCK_DEAD))) {
 		/*
@@ -2080,7 +2086,6 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 		if (!sk_locked)
 			unix_state_lock(sk);
 
-		err = 0;
 		if (sk->sk_type == SOCK_SEQPACKET) {
 			/* We are here only when racing with unix_release_sock()
 			 * is clearing @other. Never change state to TCP_CLOSE
@@ -2108,9 +2113,10 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 		goto restart;
 	}
 
-	err = -EPIPE;
-	if (other->sk_shutdown & RCV_SHUTDOWN)
+	if (other->sk_shutdown & RCV_SHUTDOWN) {
+		err = -EPIPE;
 		goto out_unlock;
+	}
 
 	if (sk->sk_type != SOCK_SEQPACKET) {
 		err = security_unix_may_send(sk->sk_socket, other->sk_socket);
-- 
2.39.5 (Apple Git-154)