[PATCH v2] selinux: vsock: Set SID for socket returned by accept()

From: David Brazdil <dbrazdil@google.com>
To: selinux@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
	Paul Moore <paul@paul-moore.com>,
	Stephen Smalley <stephen.smalley.work@gmail.com>,
	Eric Paris <eparis@parisplace.org>,
	Jeff Vander Stoep <jeffv@google.com>,
	Alistair Delva <adelva@google.com>,
	David Brazdil <dbrazdil@google.com>
Subject: [PATCH v2] selinux: vsock: Set SID for socket returned by accept()
Date: Fri, 19 Mar 2021 13:05:41 +0000	[thread overview]
Message-ID: <20210319130541.2188184-1-dbrazdil@google.com> (raw)

For AF_VSOCK, accept() currently returns sockets that are unlabelled.
Other socket families derive the child's SID from the SID of the parent
and the SID of the incoming packet. This is typically done as the
connected socket is placed in the queue that accept() removes from.

Reuse the existing 'security_sk_clone' hook to copy the SID from the
parent (server) socket to the child. There is no packet SID in this
case.

Fixes: d021c344051a ("VSOCK: Introduce VM Sockets")
Signed-off-by: David Brazdil <dbrazdil@google.com>
---
Tested on Android AOSP and Fedora 33 with v5.12-rc3.
Unit test is available here:
  https://github.com/SELinuxProject/selinux-testsuite/pull/75

Changes since v1:
  * reuse security_sk_clone instead of adding a new hook

 net/vmw_vsock/af_vsock.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 5546710d8ac1..bc7fb9bf3351 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -755,6 +755,7 @@ static struct sock *__vsock_create(struct net *net,
 		vsk->buffer_size = psk->buffer_size;
 		vsk->buffer_min_size = psk->buffer_min_size;
 		vsk->buffer_max_size = psk->buffer_max_size;
+		security_sk_clone(parent, sk);
 	} else {
 		vsk->trusted = ns_capable_noaudit(&init_user_ns, CAP_NET_ADMIN);
 		vsk->owner = get_current_cred();
-- 
2.31.0.rc2.261.g7f71774620-goog

