net/socket: Break down __sys_getsockopt

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

do_sock_getsockopt() will be called by io_uring getsockopt() command
operation in the following patch.

The same was done for the setsockopt pair.

Suggested-by: Martin KaFai Lau <martin.lau@linux.dev>
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20231016134750.1381153-5-leitao@debian.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 41 insertions, 23 deletions

diff --git a/net/socket.c b/net/socket.c
index 63be25d762f6..eb6960958026 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2333,6 +2333,43 @@ SYSCALL_DEFINE5(setsockopt, int, fd, int, level, int, optname,
 INDIRECT_CALLABLE_DECLARE(bool tcp_bpf_bypass_getsockopt(int level,
 							 int optname));
 
+int do_sock_getsockopt(struct socket *sock, bool compat, int level,
+		       int optname, sockptr_t optval, sockptr_t optlen)
+{
+	int max_optlen __maybe_unused;
+	const struct proto_ops *ops;
+	int err;
+
+	err = security_socket_getsockopt(sock, level, optname);
+	if (err)
+		return err;
+
+	if (!compat)
+		max_optlen = BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN(optlen);
+
+	ops = READ_ONCE(sock->ops);
+	if (level == SOL_SOCKET) {
+		err = sk_getsockopt(sock->sk, level, optname, optval, optlen);
+	} else if (unlikely(!ops->getsockopt)) {
+		err = -EOPNOTSUPP;
+	} else {
+		if (WARN_ONCE(optval.is_kernel || optlen.is_kernel,
+			      "Invalid argument type"))
+			return -EOPNOTSUPP;
+
+		err = ops->getsockopt(sock, level, optname, optval.user,
+				      optlen.user);
+	}
+
+	if (!compat)
+		err = BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock->sk, level, optname,
+						     optval, optlen, max_optlen,
+						     err);
+
+	return err;
+}
+EXPORT_SYMBOL(do_sock_getsockopt);
+
 /*
  *	Get a socket option. Because we don't know the option lengths we have
  *	to pass a user mode parameter for the protocols to sort out.
@@ -2340,37 +2377,18 @@ INDIRECT_CALLABLE_DECLARE(bool tcp_bpf_bypass_getsockopt(int level,
 int __sys_getsockopt(int fd, int level, int optname, char __user *optval,
 		int __user *optlen)
 {
-	int max_optlen __maybe_unused;
-	const struct proto_ops *ops;
 	int err, fput_needed;
 	struct socket *sock;
+	bool compat;
 
 	sock = sockfd_lookup_light(fd, &err, &fput_needed);
 	if (!sock)
 		return err;
 
-	err = security_socket_getsockopt(sock, level, optname);
-	if (err)
-		goto out_put;
+	compat = in_compat_syscall();
+	err = do_sock_getsockopt(sock, compat, level, optname,
+				 USER_SOCKPTR(optval), USER_SOCKPTR(optlen));
 
-	if (!in_compat_syscall())
-		max_optlen = BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN(optlen);
-
-	ops = READ_ONCE(sock->ops);
-	if (level == SOL_SOCKET)
-		err = sock_getsockopt(sock, level, optname, optval, optlen);
-	else if (unlikely(!ops->getsockopt))
-		err = -EOPNOTSUPP;
-	else
-		err = ops->getsockopt(sock, level, optname, optval,
-					    optlen);
-
-	if (!in_compat_syscall())
-		err = BPF_CGROUP_RUN_PROG_GETSOCKOPT(sock->sk, level, optname,
-						     USER_SOCKPTR(optval),
-						     USER_SOCKPTR(optlen),
-						     max_optlen, err);
-out_put:
 	fput_light(sock->file, fput_needed);
 	return err;
 }