From 1f466e1f15cf1dac7c86798d694649fc42cd868a Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 11 May 2020 13:59:13 +0200 Subject: net: cleanly handle kernel vs user buffers for ->msg_control The msg_control field in struct msghdr can either contain a user pointer when used with the recvmsg system call, or a kernel pointer when used with sendmsg. To complicate things further kernel_recvmsg can stuff a kernel pointer in and then use set_fs to make the uaccess helpers accept it. Replace it with a union of a kernel pointer msg_control field, and a user pointer msg_control_user one, and allow kernel_recvmsg operate on a proper kernel pointer using a bitfield to override the normal choice of a user pointer for recvmsg. Signed-off-by: Christoph Hellwig Signed-off-by: David S. Miller --- net/ipv4/ip_sockglue.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'net/ipv4/ip_sockglue.c') diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index aa3fd61818c4..8206047d70b6 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -1492,7 +1492,8 @@ static int do_ip_getsockopt(struct sock *sk, int level, int optname, if (sk->sk_type != SOCK_STREAM) return -ENOPROTOOPT; - msg.msg_control = (__force void *) optval; + msg.msg_control_is_user = true; + msg.msg_control_user = optval; msg.msg_controllen = len; msg.msg_flags = flags; -- cgit v1.2.3-70-g09d2