[PATCH 4.19 28/41] selinux: add support for RTM_NEWCHAIN, RTM_DELCHAIN, and RTM_GETCHAIN

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Paul Moore <paul@paul-moore.com>

commit 598e1a42e9626213565d3b22ea948ce78556512a upstream.

Commit 32a4f5ecd738 ("net: sched: introduce chain object to uapi")
added new RTM_* definitions without properly updating SELinux, this
patch adds the necessary SELinux support.

While there was a BUILD_BUG_ON() in the SELinux code to protect from
exactly this case, it was bypassed in the broken commit.  In order to
hopefully prevent this from happening in the future, add additional
comments which provide some instructions on how to resolve the
BUILD_BUG_ON() failures.

Fixes: 32a4f5ecd738 ("net: sched: introduce chain object to uapi")
Cc: <stable@vger.kernel.org> # 4.19
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 security/selinux/nlmsgtab.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

--- a/security/selinux/nlmsgtab.c
+++ b/security/selinux/nlmsgtab.c
@@ -80,6 +80,9 @@ static const struct nlmsg_perm nlmsg_rou
 	{ RTM_NEWSTATS,		NETLINK_ROUTE_SOCKET__NLMSG_READ },
 	{ RTM_GETSTATS,		NETLINK_ROUTE_SOCKET__NLMSG_READ  },
 	{ RTM_NEWCACHEREPORT,	NETLINK_ROUTE_SOCKET__NLMSG_READ },
+	{ RTM_NEWCHAIN,		NETLINK_ROUTE_SOCKET__NLMSG_WRITE },
+	{ RTM_DELCHAIN,		NETLINK_ROUTE_SOCKET__NLMSG_WRITE },
+	{ RTM_GETCHAIN,		NETLINK_ROUTE_SOCKET__NLMSG_READ  },
 };
 
 static const struct nlmsg_perm nlmsg_tcpdiag_perms[] =
@@ -158,7 +161,11 @@ int selinux_nlmsg_lookup(u16 sclass, u16
 
 	switch (sclass) {
 	case SECCLASS_NETLINK_ROUTE_SOCKET:
-		/* RTM_MAX always point to RTM_SETxxxx, ie RTM_NEWxxx + 3 */
+		/* RTM_MAX always points to RTM_SETxxxx, ie RTM_NEWxxx + 3.
+		 * If the BUILD_BUG_ON() below fails you must update the
+		 * structures at the top of this file with the new mappings
+		 * before updating the BUILD_BUG_ON() macro!
+		 */
 		BUILD_BUG_ON(RTM_MAX != (RTM_NEWCHAIN + 3));
 		err = nlmsg_perm(nlmsg_type, perm, nlmsg_route_perms,
 				 sizeof(nlmsg_route_perms));
@@ -170,6 +177,10 @@ int selinux_nlmsg_lookup(u16 sclass, u16
 		break;
 
 	case SECCLASS_NETLINK_XFRM_SOCKET:
+		/* If the BUILD_BUG_ON() below fails you must update the
+		 * structures at the top of this file with the new mappings
+		 * before updating the BUILD_BUG_ON() macro!
+		 */
 		BUILD_BUG_ON(XFRM_MSG_MAX != XFRM_MSG_MAPPING);
 		err = nlmsg_perm(nlmsg_type, perm, nlmsg_xfrm_perms,
 				 sizeof(nlmsg_xfrm_perms));