[PATCH v3] Allow UDP cmsghdrs through io_uring

[Victor Stewart]

---
 net/ipv4/af_inet.c  | 1 +
 net/ipv6/af_inet6.c | 1 +
 net/socket.c        | 8 +++++---
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index b7260c8cef2e..c9fd5e7cfd6e 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1052,6 +1052,7 @@ EXPORT_SYMBOL(inet_stream_ops);
 
 const struct proto_ops inet_dgram_ops = {
        .family            = PF_INET,
+       .flags             = PROTO_CMSG_DATA_ONLY,
        .owner             = THIS_MODULE,
        .release           = inet_release,
        .bind              = inet_bind,
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index e648fbebb167..560f45009d06 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -695,6 +695,7 @@ const struct proto_ops inet6_stream_ops = {
 
 const struct proto_ops inet6_dgram_ops = {
        .family            = PF_INET6,
+       .flags             = PROTO_CMSG_DATA_ONLY,
        .owner             = THIS_MODULE,
        .release           = inet6_release,
        .bind              = inet6_bind,
diff --git a/net/socket.c b/net/socket.c
index 6e6cccc2104f..6995835d6355 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2416,9 +2416,11 @@ static int ___sys_sendmsg(struct socket *sock, struct 
user_msghdr __user *msg,
 long __sys_sendmsg_sock(struct socket *sock, struct msghdr *msg,
                        unsigned int flags)
 {
-       /* disallow ancillary data requests from this path */
-       if (msg->msg_control || msg->msg_controllen)
-               return -EINVAL;
+       if (msg->msg_control || msg->msg_controllen) {
+               /* disallow ancillary data reqs unless cmsg is plain data */
+               if (!(sock->ops->flags & PROTO_CMSG_DATA_ONLY))
+                       return -EINVAL;
+       }
 
        return ____sys_sendmsg(sock, msg, flags, NULL, 0);
 }
-- 
2.26.2