commit a7b75c5a8c41445f33efb663887ff5f5c3b4454b
author Christoph Hellwig <hch@lst.de> Thu Jul 23 08:09:07 2020 +0200
committer David S. Miller <davem@davemloft.net> Fri Jul 24 15:41:54 2020 -0700
tree a87e011ba3a0d76fda030b3a62080caa97fae1ef
parent d38d2b00ba64b3f2f30d70a7929000606d2c4509

net: pass a sockptr_t into ->setsockopt

Rework the remaining setsockopt code to pass a sockptr_t instead of a
plain user pointer.  This removes the last remaining set_fs(KERNEL_DS)
outside of architecture specific code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Stefan Schmidt <stefan@datenfreihafen.org> [ieee802154]
Acked-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/socket.c

diff --git a/net/socket.c b/net/socket.c
index c97f83d..e44b8ac 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2094,10 +2094,10 @@ static bool sock_use_custom_sol_socket(const struct socket *sock)
  *	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 *optval,
+int __sys_setsockopt(int fd, int level, int optname, char __user *user_optval,
 		int optlen)
 {
-	mm_segment_t oldfs = get_fs();
+	sockptr_t optval = USER_SOCKPTR(user_optval);
 	char *kernel_optval = NULL;
 	int err, fput_needed;
 	struct socket *sock;
@@ -2115,7 +2115,7 @@ int __sys_setsockopt(int fd, int level, int optname, char __user *optval,
 
 	if (!in_compat_syscall())
 		err = BPF_CGROUP_RUN_PROG_SETSOCKOPT(sock->sk, &level, &optname,
-						     optval, &optlen,
+						     user_optval, &optlen,
 						     &kernel_optval);
 	if (err < 0)
 		goto out_put;
@@ -2124,25 +2124,16 @@ int __sys_setsockopt(int fd, int level, int optname, char __user *optval,
 		goto out_put;
 	}
 
-	if (kernel_optval) {
-		set_fs(KERNEL_DS);
-		optval = (char __user __force *)kernel_optval;
-	}
-
+	if (kernel_optval)
+		optval = KERNEL_SOCKPTR(kernel_optval);
 	if (level == SOL_SOCKET && !sock_use_custom_sol_socket(sock))
-		err = sock_setsockopt(sock, level, optname,
-				      USER_SOCKPTR(optval), optlen);
+		err = sock_setsockopt(sock, level, optname, optval, optlen);
 	else if (unlikely(!sock->ops->setsockopt))
 		err = -EOPNOTSUPP;
 	else
 		err = sock->ops->setsockopt(sock, level, optname, optval,
 					    optlen);
-
-	if (kernel_optval) {
-		set_fs(oldfs);
-		kfree(kernel_optval);
-	}
-
+	kfree(kernel_optval);
 out_put:
 	fput_light(sock->file, fput_needed);
 	return err;