[PATCH bpf-next v4 1/5] net: Add connect_socket() helper

[Mahe Tardy <mahe.tardy@gmail.com>]

Add a helper that connects an existing socket while invoking the LSM
hook. Reuse it in __sys_connect_file() to avoid duplicating the connect
logic. Other socket operations have equivalent helpers that trigger the
appropriate LSM hooks that can be reused, this one was the only one
missing.

Signed-off-by: Mahe Tardy <mahe.tardy@gmail.com>
---
 include/linux/socket.h |  2 ++
 net/socket.c           | 32 ++++++++++++++++++--------------
 2 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/include/linux/socket.h b/include/linux/socket.h
index 2a8d7b14f1d1..8964528e3823 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -461,6 +461,8 @@ extern struct file *__sys_socket_file(int family, int type, int protocol);
 extern int __sys_bind(int fd, struct sockaddr __user *umyaddr, int addrlen);
 extern int __sys_bind_socket(struct socket *sock, struct sockaddr_storage *address,
 			     int addrlen);
+extern int connect_socket(struct socket *sock, struct sockaddr_storage *addr,
+				int addrlen, int flags);
 extern int __sys_connect_file(struct file *file, struct sockaddr_storage *addr,
 			      int addrlen, int file_flags);
 extern int __sys_connect(int fd, struct sockaddr __user *uservaddr,
diff --git a/net/socket.c b/net/socket.c
index 63c69a0fa74e..126a674f534d 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2103,6 +2103,20 @@ SYSCALL_DEFINE3(accept, int, fd, struct sockaddr __user *, upeer_sockaddr,
 	return __sys_accept4(fd, upeer_sockaddr, upeer_addrlen, 0);
 }

+int connect_socket(struct socket *sock, struct sockaddr_storage *address,
+			 int addrlen, int flags)
+{
+	int err;
+
+	err = security_socket_connect(sock, (struct sockaddr *)address, addrlen);
+	if (err)
+		return err;
+
+	return READ_ONCE(sock->ops)->connect(sock,
+				    (struct sockaddr_unsized *)address,
+				    addrlen, flags);
+}
+
 /*
  *	Attempt to connect to a socket with the server address.  The address
  *	is in user space so we verify it is OK and move it to kernel space.
@@ -2119,23 +2133,13 @@ int __sys_connect_file(struct file *file, struct sockaddr_storage *address,
 		       int addrlen, int file_flags)
 {
 	struct socket *sock;
-	int err;

 	sock = sock_from_file(file);
-	if (!sock) {
-		err = -ENOTSOCK;
-		goto out;
-	}
-
-	err =
-	    security_socket_connect(sock, (struct sockaddr *)address, addrlen);
-	if (err)
-		goto out;
+	if (!sock)
+		return -ENOTSOCK;

-	err = READ_ONCE(sock->ops)->connect(sock, (struct sockaddr_unsized *)address,
-					    addrlen, sock->file->f_flags | file_flags);
-out:
-	return err;
+	return connect_socket(sock, address, addrlen,
+				    sock->file->f_flags | file_flags);
 }

 int __sys_connect(int fd, struct sockaddr __user *uservaddr, int addrlen)
--
2.34.1