[src/trunk]: src/lib/librumphijack rumphijack: don't modify a cmsg on just va...

[ozaki-r <ozaki-r%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/040e8ecc99c8
branches:  trunk
changeset: 323737:040e8ecc99c8
user:      ozaki-r <ozaki-r%NetBSD.org@localhost>
date:      Thu Jun 28 06:20:36 2018 +0000

description:
rumphijack: don't modify a cmsg on just validating it

Pointed out by k-goda@IIJ

diffstat:

 lib/librumphijack/hijack.c |  31 +++++++++++++++++++++++--------
 1 files changed, 23 insertions(+), 8 deletions(-)

diffs (88 lines):

diff -r bda396269434 -r 040e8ecc99c8 lib/librumphijack/hijack.c
--- a/lib/librumphijack/hijack.c        Thu Jun 28 06:02:24 2018 +0000
+++ b/lib/librumphijack/hijack.c        Thu Jun 28 06:20:36 2018 +0000
@@ -1,4 +1,4 @@
-/*      $NetBSD: hijack.c,v 1.124 2017/10/23 06:52:17 ozaki-r Exp $    */
+/*      $NetBSD: hijack.c,v 1.125 2018/06/28 06:20:36 ozaki-r Exp $    */
 
 /*-
  * Copyright (c) 2011 Antti Kantee.  All Rights Reserved.
@@ -34,7 +34,7 @@
 #include <rump/rumpuser_port.h>
 
 #if !defined(lint)
-__RCSID("$NetBSD: hijack.c,v 1.124 2017/10/23 06:52:17 ozaki-r Exp $");
+__RCSID("$NetBSD: hijack.c,v 1.125 2018/06/28 06:20:36 ozaki-r Exp $");
 #endif
 
 #include <sys/param.h>
@@ -1587,7 +1587,7 @@
  */
 
 static int
-msg_convert(struct msghdr *msg, int (*func)(int))
+_msg_convert_fds(struct msghdr *msg, int (*func)(int), bool dryrun)
 {
        struct cmsghdr *cmsg;
 
@@ -1607,7 +1607,8 @@
                                if (newval < 0) {
                                        return ENOTSUP;
                                }
-                               *fdp = newval;
+                               if (!dryrun)
+                                       *fdp = newval;
                                fdp++;
                        }
                }
@@ -1615,6 +1616,20 @@
        return 0;
 }
 
+static int
+msg_convert_fds(struct msghdr *msg, int (*func)(int))
+{
+
+       return _msg_convert_fds(msg, func, false);
+}
+
+static int
+msg_check_fds(struct msghdr *msg, int (*func)(int))
+{
+
+       return _msg_convert_fds(msg, func, true);
+}
+
 ssize_t
 recvmsg(int fd, struct msghdr *msg, int flags)
 {
@@ -1636,9 +1651,9 @@
         * convert descriptors in the message.
         */
        if (isrump) {
-               msg_convert(msg, fd_rump2host);
+               msg_convert_fds(msg, fd_rump2host);
        } else {
-               msg_convert(msg, fd_host2host);
+               msg_convert_fds(msg, fd_host2host);
        }
        return ret;
 }
@@ -1681,7 +1696,7 @@
        /*
         * reject descriptors from a different kernel.
         */
-       error = msg_convert(__UNCONST(msg),
+       error = msg_check_fds(__UNCONST(msg),
            isrump ? fd_check_rump: fd_check_host);
        if (error != 0) {
                errno = error;
@@ -1700,7 +1715,7 @@
                 *
                 * it's safer to copy and modify instead.
                 */
-               msg_convert(__UNCONST(msg), fd_host2rump);
+               msg_convert_fds(__UNCONST(msg), fd_host2rump);
                op_sendmsg = GETSYSCALL(rump, SENDMSG);
        } else {
                op_sendmsg = GETSYSCALL(host, SENDMSG);