1 files changed, 48 insertions, 30 deletions

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 52b155123985..a8895786e016 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -646,9 +646,6 @@ static void unix_sock_destructor(struct sock *sk)
 		return;
 	}
 
-	if (sk->sk_peer_pid)
-		pidfs_put_pid(sk->sk_peer_pid);
-
 	if (u->addr)
 		unix_release_addr(u->addr);
 
@@ -780,7 +777,6 @@ static void drop_peercred(struct unix_peercred *peercred)
 	swap(peercred->peer_pid, pid);
 	swap(peercred->peer_cred, cred);
 
-	pidfs_put_pid(pid);
 	put_pid(pid);
 	put_cred(cred);
 }
@@ -813,7 +809,6 @@ static void copy_peercred(struct sock *sk, struct sock *peersk)
 
 	spin_lock(&sk->sk_peer_lock);
 	sk->sk_peer_pid = get_pid(peersk->sk_peer_pid);
-	pidfs_get_pid(sk->sk_peer_pid);
 	sk->sk_peer_cred = get_cred(peersk->sk_peer_cred);
 	spin_unlock(&sk->sk_peer_lock);
 }
@@ -1945,7 +1940,7 @@ static void unix_destruct_scm(struct sk_buff *skb)
 	struct scm_cookie scm;
 
 	memset(&scm, 0, sizeof(scm));
-	scm.pid  = UNIXCB(skb).pid;
+	scm.pid = UNIXCB(skb).pid;
 	if (UNIXCB(skb).fp)
 		unix_detach_fds(&scm, skb);
 
@@ -1971,22 +1966,46 @@ static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool sen
 	return err;
 }
 
-/*
+static void unix_skb_to_scm(struct sk_buff *skb, struct scm_cookie *scm)
+{
+	scm_set_cred(scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid);
+	unix_set_secdata(scm, skb);
+}
+
+/**
+ * unix_maybe_add_creds() - Adds current task uid/gid and struct pid to skb if needed.
+ * @skb: skb to attach creds to.
+ * @sk: Sender sock.
+ * @other: Receiver sock.
+ *
  * Some apps rely on write() giving SCM_CREDENTIALS
  * We include credentials if source or destination socket
  * asserted SOCK_PASSCRED.
+ *
+ * Context: May sleep.
+ * Return: On success zero, on error a negative error code is returned.
  */
-static void unix_maybe_add_creds(struct sk_buff *skb, const struct sock *sk,
-				 const struct sock *other)
+static int unix_maybe_add_creds(struct sk_buff *skb, const struct sock *sk,
+				const struct sock *other)
 {
 	if (UNIXCB(skb).pid)
-		return;
+		return 0;
 
 	if (unix_may_passcred(sk) || unix_may_passcred(other) ||
 	    !other->sk_socket) {
-		UNIXCB(skb).pid = get_pid(task_tgid(current));
+		struct pid *pid;
+		int err;
+
+		pid = task_tgid(current);
+		err = pidfs_register_pid(pid);
+		if (unlikely(err))
+			return err;
+
+		UNIXCB(skb).pid = get_pid(pid);
 		current_uid_gid(&UNIXCB(skb).uid, &UNIXCB(skb).gid);
 	}
+
+	return 0;
 }
 
 static bool unix_skb_scm_eq(struct sk_buff *skb,
@@ -2121,6 +2140,10 @@ lookup:
 		goto out_sock_put;
 	}
 
+	err = unix_maybe_add_creds(skb, sk, other);
+	if (err)
+		goto out_sock_put;
+
 restart:
 	sk_locked = 0;
 	unix_state_lock(other);
@@ -2229,7 +2252,6 @@ restart_locked:
 	if (sock_flag(other, SOCK_RCVTSTAMP))
 		__net_timestamp(skb);
 
-	unix_maybe_add_creds(skb, sk, other);
 	scm_stat_add(other, skb);
 	skb_queue_tail(&other->sk_receive_queue, skb);
 	unix_state_unlock(other);
@@ -2273,6 +2295,10 @@ static int queue_oob(struct sock *sk, struct msghdr *msg, struct sock *other,
 	if (err < 0)
 		goto out;
 
+	err = unix_maybe_add_creds(skb, sk, other);
+	if (err)
+		goto out;
+
 	skb_put(skb, 1);
 	err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, 1);
 
@@ -2292,7 +2318,6 @@ static int queue_oob(struct sock *sk, struct msghdr *msg, struct sock *other,
 		goto out_unlock;
 	}
 
-	unix_maybe_add_creds(skb, sk, other);
 	scm_stat_add(other, skb);
 
 	spin_lock(&other->sk_receive_queue.lock);
@@ -2386,6 +2411,10 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg,
 
 		fds_sent = true;
 
+		err = unix_maybe_add_creds(skb, sk, other);
+		if (err)
+			goto out_free;
+
 		if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES)) {
 			skb->ip_summed = CHECKSUM_UNNECESSARY;
 			err = skb_splice_from_iter(skb, &msg->msg_iter, size,
@@ -2416,7 +2445,6 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg,
 			goto out_free;
 		}
 
-		unix_maybe_add_creds(skb, sk, other);
 		scm_stat_add(other, skb);
 		skb_queue_tail(&other->sk_receive_queue, skb);
 		unix_state_unlock(other);
@@ -2564,8 +2592,7 @@ int __unix_dgram_recvmsg(struct sock *sk, struct msghdr *msg, size_t size,
 
 	memset(&scm, 0, sizeof(scm));
 
-	scm_set_cred(&scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid);
-	unix_set_secdata(&scm, skb);
+	unix_skb_to_scm(skb, &scm);
 
 	if (!(flags & MSG_PEEK)) {
 		if (UNIXCB(skb).fp)
@@ -2954,8 +2981,7 @@ unlock:
 				break;
 		} else if (unix_may_passcred(sk)) {
 			/* Copy credentials */
-			scm_set_cred(&scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid);
-			unix_set_secdata(&scm, skb);
+			unix_skb_to_scm(skb, &scm);
 			check_creds = true;
 		}
 
@@ -3191,7 +3217,6 @@ EXPORT_SYMBOL_GPL(unix_outq_len);
 
 static int unix_open_file(struct sock *sk)
 {
-	struct path path;
 	struct file *f;
 	int fd;
 
@@ -3201,27 +3226,20 @@ static int unix_open_file(struct sock *sk)
 	if (!smp_load_acquire(&unix_sk(sk)->addr))
 		return -ENOENT;
 
-	path = unix_sk(sk)->path;
-	if (!path.dentry)
+	if (!unix_sk(sk)->path.dentry)
 		return -ENOENT;
 
-	path_get(&path);
-
 	fd = get_unused_fd_flags(O_CLOEXEC);
 	if (fd < 0)
-		goto out;
+		return fd;
 
-	f = dentry_open(&path, O_PATH, current_cred());
+	f = dentry_open(&unix_sk(sk)->path, O_PATH, current_cred());
 	if (IS_ERR(f)) {
 		put_unused_fd(fd);
-		fd = PTR_ERR(f);
-		goto out;
+		return PTR_ERR(f);
 	}
 
 	fd_install(fd, f);
-out:
-	path_put(&path);
-
 	return fd;
 }