net/socket: Break down __sys_setsockopt

Split __sys_setsockopt() into two functions by removing the core
logic into a sub-function (do_sock_setsockopt()). This will avoid
code duplication when doing the same operation in other callers, for
instance.

do_sock_setsockopt() will be called by io_uring setsockopt() command
operation in the following patch.

Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20231016134750.1381153-4-leitao@debian.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 25 insertions, 14 deletions

diff --git a/net/socket.c b/net/socket.c
index 9a43f6e850c7..63be25d762f6 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2262,31 +2262,21 @@ static bool sock_use_custom_sol_socket(const struct socket *sock)
 	return test_bit(SOCK_CUSTOM_SOCKOPT, &sock->flags);
 }
 
-/*
- *	Set a socket option. Because we don't know the option lengths we have
- *	to pass the user mode parameter for the protocols to sort out.
- */
-int __sys_setsockopt(int fd, int level, int optname, char __user *user_optval,
-		int optlen)
+int do_sock_setsockopt(struct socket *sock, bool compat, int level,
+		       int optname, sockptr_t optval, int optlen)
 {
-	sockptr_t optval = USER_SOCKPTR(user_optval);
 	const struct proto_ops *ops;
 	char *kernel_optval = NULL;
-	int err, fput_needed;
-	struct socket *sock;
+	int err;
 
 	if (optlen < 0)
 		return -EINVAL;
 
-	sock = sockfd_lookup_light(fd, &err, &fput_needed);
-	if (!sock)
-		return err;
-
 	err = security_socket_setsockopt(sock, level, optname);
 	if (err)
 		goto out_put;
 
-	if (!in_compat_syscall())
+	if (!compat)
 		err = BPF_CGROUP_RUN_PROG_SETSOCKOPT(sock->sk, &level, &optname,
 						     optval, &optlen,
 						     &kernel_optval);
@@ -2309,6 +2299,27 @@ int __sys_setsockopt(int fd, int level, int optname, char __user *user_optval,
 					    optlen);
 	kfree(kernel_optval);
 out_put:
+	return err;
+}
+EXPORT_SYMBOL(do_sock_setsockopt);
+
+/* Set a socket option. Because we don't know the option lengths we have
+ * to pass the user mode parameter for the protocols to sort out.
+ */
+int __sys_setsockopt(int fd, int level, int optname, char __user *user_optval,
+		     int optlen)
+{
+	sockptr_t optval = USER_SOCKPTR(user_optval);
+	bool compat = in_compat_syscall();
+	int err, fput_needed;
+	struct socket *sock;
+
+	sock = sockfd_lookup_light(fd, &err, &fput_needed);
+	if (!sock)
+		return err;
+
+	err = do_sock_setsockopt(sock, compat, level, optname, optval, optlen);
+
 	fput_light(sock->file, fput_needed);
 	return err;
 }