[Openvpn-devel] [XS] Change in openvpn[master]: sitnl: set FD_CLOEXEC on socket to prevent abuse

[ordex (C. Review) <ge...@op...>]

Attention is currently required from: flichtenheld, plaisthos.

Hello plaisthos, flichtenheld,

I'd like you to do a code review.
Please visit

    http://gerrit.openvpn.net/c/openvpn/+/1314?usp=email

to review the following change.


Change subject: sitnl: set FD_CLOEXEC on socket to prevent abuse
......................................................................

sitnl: set FD_CLOEXEC on socket to prevent abuse

Since OpenVPN spawns various child processes, it is important
that sockets are closed after calling exec.

The sitnl socket didn't have the right flag set, resulting
in it surviving in, for example, connect/disconnect scripts
and giving the latter a chance to abuse the socket.

Ensure this doesn't happen by setting FD_CLOEXEC on
this socket right after creation.

Reported-by: ZeroPath (https://zeropath.com/)
Change-Id: I54845bf4dd17d06cfc3b402f188795f74f4b1d3e
Signed-off-by: Antonio Quartulli <an...@ma...>
---
M src/openvpn/networking_sitnl.c
1 file changed, 3 insertions(+), 0 deletions(-)



  git pull ssh://gerrit.openvpn.net:29418/openvpn refs/changes/14/1314/1

diff --git a/src/openvpn/networking_sitnl.c b/src/openvpn/networking_sitnl.c
index b3adb16..a959fa8 100644
--- a/src/openvpn/networking_sitnl.c
+++ b/src/openvpn/networking_sitnl.c
@@ -181,6 +181,9 @@
         return fd;
     }
 
+    /* set close on exec to avoid child processes access the socket */
+    set_cloexec(fd);
+
     if (setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &sndbuf, sizeof(sndbuf)) < 0)
     {
         msg(M_WARN | M_ERRNO, "%s: SO_SNDBUF", __func__);

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Gerrit-MessageType: newchange
Gerrit-Project: openvpn
Gerrit-Branch: master
Gerrit-Change-Id: I54845bf4dd17d06cfc3b402f188795f74f4b1d3e
Gerrit-Change-Number: 1314
Gerrit-PatchSet: 1
Gerrit-Owner: ordex <an...@ma...>
Gerrit-Reviewer: flichtenheld <fr...@li...>
Gerrit-Reviewer: plaisthos <arn...@rf...>
Gerrit-CC: openvpn-devel <ope...@li...>
Gerrit-Attention: plaisthos <arn...@rf...>
Gerrit-Attention: flichtenheld <fr...@li...>