[PATCH 5/5] net: sock_aio_write: set CMSG_MSG_COMPAT flag if is_compat_task

[Florian Westphal <fw@strlen.de>]

From: Florian Westphal <fwestphal@astaro.com>

some programs (e.g. pluto ike daemon), send netlink data to the
kernel via write().

So far, the CMSG_MSG_COMPAT flag is not set in this case, which
results in the kernel interpreting the netlink data the wrong way.

An alternative solution is to switch userspace to sendmsg() when
using netlink sockets.

Signed-off-by: Florian Westphal <fwestphal@astaro.com>
---
 net/socket.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/net/socket.c b/net/socket.c
index 769c386..e6a6a67 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -837,6 +837,10 @@ static ssize_t do_sock_write(struct msghdr *msg, struct kiocb *iocb,
 	msg->msg_iov = (struct iovec *)iov;
 	msg->msg_iovlen = nr_segs;
 	msg->msg_flags = (file->f_flags & O_NONBLOCK) ? MSG_DONTWAIT : 0;
+#ifdef CONFIG_COMPAT
+	if (is_compat_task())
+		msg->msg_flags |= MSG_CMSG_COMPAT;
+#endif
 	if (sock->type == SOCK_SEQPACKET)
 		msg->msg_flags |= MSG_EOR;
 
-- 
1.6.3.3