svn commit: r364409 - in head/sys: kern sys

[Rick Macklem]

Author: rmacklem
Date: Wed Aug 19 23:42:33 2020
New Revision: 364409
URL: https://svnweb.freebsd.org/changeset/base/364409

Log:
  Add the MSG_TLSAPPDATA flag to indicate "return ENXIO" for non-application TLS
  data records.
  
  The kernel RPC cannot process non-application data records when
  using TLS. It must to an upcall to a userspace daemon that will
  call SSL_read() to process them.
  
  This patch adds a new flag called MSG_TLSAPPDATA that the kernel
  RPC can use to tell sorecieve() to return ENXIO instead of a non-application
  data record, when that is what is at the top of the receive queue.
  I put the code in #ifdef KERN_TLS/#endif, although it will build without
  that, so that it is recognized as only useful when KERN_TLS is enabled.
  The alternative to doing this is to have the kernel RPC re-queue the
  non-application data message after receiving it, but that seems more
  complicated and might introduce message ordering issues when there
  are multiple non-application data records one after another.
  
  I do not know what, if any, changes will be required to support TLS1.3.
  
  Reviewed by:	glebius
  Differential Revision:	https://reviews.freebsd.org/D25923

Modified:
  head/sys/kern/uipc_socket.c
  head/sys/sys/socket.h

Modified: head/sys/kern/uipc_socket.c
==============================================================================
--- head/sys/kern/uipc_socket.c	Wed Aug 19 20:41:22 2020	(r364408)
+++ head/sys/kern/uipc_socket.c	Wed Aug 19 23:42:33 2020	(r364409)
@@ -2056,6 +2056,32 @@ dontblock:
 	if (m != NULL && m->m_type == MT_CONTROL) {
 		struct mbuf *cm = NULL, *cmn;
 		struct mbuf **cme = &cm;
+#ifdef KERN_TLS
+		struct cmsghdr *cmsg;
+		struct tls_get_record tgr;
+
+		/*
+		 * For MSG_TLSAPPDATA, check for a non-application data
+		 * record.  If found, return ENXIO without removing
+		 * it from the receive queue.  This allows a subsequent
+		 * call without MSG_TLSAPPDATA to receive it.
+		 * Note that, for TLS, there should only be a single
+		 * control mbuf with the TLS_GET_RECORD message in it.
+		 */
+		if (flags & MSG_TLSAPPDATA) {
+			cmsg = mtod(m, struct cmsghdr *);
+			if (cmsg->cmsg_type == TLS_GET_RECORD &&
+			    cmsg->cmsg_len == CMSG_LEN(sizeof(tgr))) {
+				memcpy(&tgr, CMSG_DATA(cmsg), sizeof(tgr));
+				/* This will need to change for TLS 1.3. */
+				if (tgr.tls_type != TLS_RLTYPE_APP) {
+					SOCKBUF_UNLOCK(&so->so_rcv);
+					error = ENXIO;
+					goto release;
+				}
+			}
+		}
+#endif
 
 		do {
 			if (flags & MSG_PEEK) {

Modified: head/sys/sys/socket.h
==============================================================================
--- head/sys/sys/socket.h	Wed Aug 19 20:41:22 2020	(r364408)
+++ head/sys/sys/socket.h	Wed Aug 19 23:42:33 2020	(r364409)
@@ -468,6 +468,7 @@ struct msghdr {
 #endif
 #ifdef _KERNEL
 #define	MSG_MORETOCOME	 0x00100000	/* additional data pending */
+#define	MSG_TLSAPPDATA	 0x00200000	/* only soreceive() app. data (TLS) */
 #endif
 
 /*