net: Allow MSG_EOR in each msghdr of sendmmsg

This patch allows setting MSG_EOR in each individual msghdr passed
in sendmmsg. This allows a sendmmsg to send multiple messages when
using SOCK_SEQPACKET.
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/socket.c

@@ -1875,7 +1875,8 @@ static int copy_msghdr_from_user(struct msghdr *kmsg,
 
 static int ___sys_sendmsg(struct socket *sock, struct user_msghdr __user *msg,
 			 struct msghdr *msg_sys, unsigned int flags,
-			 struct used_address *used_address)
+			 struct used_address *used_address,
+			 unsigned int allowed_msghdr_flags)
 {
 	struct compat_msghdr __user *msg_compat =
 	    (struct compat_msghdr __user *)msg;
@@ -1901,6 +1902,7 @@ static int ___sys_sendmsg(struct socket *sock, struct user_msghdr __user *msg,
 
 	if (msg_sys->msg_controllen > INT_MAX)
 		goto out_freeiov;
+	flags |= (msg_sys->msg_flags & allowed_msghdr_flags);
 	ctl_len = msg_sys->msg_controllen;
 	if ((MSG_CMSG_COMPAT & flags) && ctl_len) {
 		err =
@@ -1979,7 +1981,7 @@ long __sys_sendmsg(int fd, struct user_msghdr __user *msg, unsigned flags)
 	if (!sock)
 		goto out;
 
-	err = ___sys_sendmsg(sock, msg, &msg_sys, flags, NULL);
+	err = ___sys_sendmsg(sock, msg, &msg_sys, flags, NULL, 0);
 
 	fput_light(sock->file, fput_needed);
 out:
@@ -2024,7 +2026,7 @@ int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
 	while (datagrams < vlen) {
 		if (MSG_CMSG_COMPAT & flags) {
 			err = ___sys_sendmsg(sock, (struct user_msghdr __user *)compat_entry,
-					     &msg_sys, flags, &used_address);
+					     &msg_sys, flags, &used_address, MSG_EOR);
 			if (err < 0)
 				break;
 			err = __put_user(err, &compat_entry->msg_len);
@@ -2032,7 +2034,7 @@ int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
 		} else {
 			err = ___sys_sendmsg(sock,
 					     (struct user_msghdr __user *)entry,
-					     &msg_sys, flags, &used_address);
+					     &msg_sys, flags, &used_address, MSG_EOR);
 			if (err < 0)
 				break;
 			err = put_user(err, &entry->msg_len);