net: rework recvmsg handler msg_name and msg_namelen logic

[mirror_ubuntu-bionic-kernel.git] / include / linux / net.h

diff --git a/include/linux/net.h b/include/linux/net.h
index b292a04355717a503b093e2d2c424cf92951415f..4bcee94cef9314c44dfaa94fb17d3c905fefee08 100644 (file)
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -164,6 +164,14 @@ struct proto_ops {
 #endif
        int             (*sendmsg)   (struct kiocb *iocb, struct socket *sock,
                                      struct msghdr *m, size_t total_len);
+       /* Notes for implementing recvmsg:
+        * ===============================
+        * msg->msg_namelen should get updated by the recvmsg handlers
+        * iff msg_name != NULL. It is by default 0 to prevent
+        * returning uninitialized memory to user space.  The recvfrom
+        * handlers can assume that msg.msg_name is either NULL or has
+        * a minimum size of sizeof(struct sockaddr_storage).
+        */
        int             (*recvmsg)   (struct kiocb *iocb, struct socket *sock,
                                      struct msghdr *m, size_t total_len,
                                      int flags);