On 09/25/2018 07:36 PM, TongZhang wrote:
ocfs2 is using sock_create instead of sock_create_kern in kernel v4.18.5.
fs/ocfs2/cluster/tcp.c: 1636
https://elixir.bootlin.com/linux/v4.18.5/source/fs/ocfs2/cluster/tcp.c#L1636
ret = sock_create(PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock);
fs/ocfs2/cluster/tcp.c: 2035
https://elixir.bootlin.com/linux/v4.18.5/source/fs/ocfs2/cluster/tcp.c#L2035
ret = sock_create(PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock);
Yes, I think that's the real bug here. Unless the socket is in fact
exposed for direct use by userspace, it ought to be using
sock_create_kern() or similar. I would suggest that you verify that the
socket is never returned to userspace, and then submit a patch switching
the code to using sock_create_kern().
On Sep 25, 2018, at 2:44 PM, Stephen Smalley <[email protected]> wrote:
On 09/25/2018 01:27 PM, Tong Zhang wrote:
Kernel Version: 4.18.5
Problem Description:
We found several leaking path or inconsistency LSM design issue in fs/net.
Currently we can only observe sock creation from kernel and all
bind/listen/connect are not sent to LSM.
So, we think that those net/socket related stuff should all go through LSM
check and being audited
even it is not a user thread or process.
Here’s an example where we have a check:
in fs/ocfs2/cluster/tcp.c:2035 o2net_open_listening_sock() a sock is created
using sock_create(),
where a LSM check security_socket_create is called(net/socket.c:1242)
And where we don’t have a check
fs/ocfs2/cluster/tcp.c:2052 bind
fs/ocfs2/cluster/tcp.c:2059 listen
fs/dlm/lowcomms.c:1264 bind
fs/dlm/lowcomms.c:1278 listen
fs/dlm/lowcomms.c:1354 listen
several places that use kernel_bind/kernel_listen/kernel_connect
net/socket.c:3231 kernel_bind
net/socket.c:3237 kernel_listen
net/socket.c:3286 kernel_connect
That's intentional. LSM isn't trying to mediate kernel-internal operations,
and we do not want to apply permission checks against the credentials of the
current userspace process for such operations. ocfs2 should likely be using
sock_create_kern.
