On Thu, Dec 3, 2020 at 12:24 PM Mat Martineau
[off-list ref] wrote:

On Wed, 2 Dec 2020, Paolo Abeni wrote:

quoted

On Wed, 2020-12-02 at 11:31 +0100, Paolo Abeni wrote:

quoted

The MPTCP protocol uses a specific protocol value, even if
it's an extension to TCP. Additionally, MPTCP sockets
could 'fall-back' to TCP at run-time, depending on peer MPTCP
support and available resources.

As a consequence of the specific protocol number, selinux
applies the raw_socket class to MPTCP sockets.

Existing TCP application converted to MPTCP - or forced to
use MPTCP socket with user-space hacks - will need an
updated policy to run successfully.

This change lets selinux attach the TCP socket class to
MPTCP sockets, too, so that no policy changes are needed in
the above scenario.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
 security/selinux/hooks.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 6b1826fc3658..9a6b4bf1bc5b 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c

@@ -1120,7 +1120,8 @@ static inline u16 inode_mode_to_security_class(umode_t mode)

 static inline int default_protocol_stream(int protocol)
 {
-    return (protocol == IPPROTO_IP || protocol == IPPROTO_TCP);
+    return (protocol == IPPROTO_IP || protocol == IPPROTO_TCP ||
+            protocol == IPPROTO_MPTCP);
 }

This looks like a good default to me.

quoted

quoted

 static inline int default_protocol_dgram(int protocol)

@@ -1152,7 +1153,7 @@ static inline u16 socket_type_to_security_class(int family, int type, int protoc
                             return SECCLASS_TCP_SOCKET;
                     else if (extsockclass && protocol == IPPROTO_SCTP)
                             return SECCLASS_SCTP_SOCKET;
-                    else
+                    elseextsockclass

Whoops, my bad! I don't know how this chunk slipped-in. I'll fix it in
the formal submission for inclusion, if there is agreement on this
change.

Ok, looks fine to send after fixup.

I'm not very well versed in MPTCP, but this *seems* okay to me, minus
the else-crud chunk.  Just to confirm my understanding, while MPTCP
allows one TCP connection/stream to be subdivided and distributed
across multiple interfaces, it does not allow multiple TCP streams to
be multiplexed on a single connection, yes?

I think there may be a small fix required to smack too, but that's an
entirely different patch.

It would probably be a good idea to CC the LSM list just to make sure
all of the LSMs are made aware (done on this email).

-- 
paul moore
www.paul-moore.com