net: Use ns_capable_noaudit() when determining net sysctl permissions

The capability check should not be audited since it is only being used
to determine the inode permissions. A failed check does not indicate a
violation of security policy but, when an LSM is enabled, a denial audit
message was being generated.

The denial audit message caused confusion for some application authors
because root-running Go applications always triggered the denial. To
prevent this confusion, the capability check in net_ctl_permissions() is
switched to the noaudit variant.

BugLink: https://launchpad.net/bugs/1465724
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
[dtor: reapplied after e79c6a4fc923 ("net: make net namespace sysctls
belong to container's owner") accidentally reverted the change.]
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sysctl_net.c b/net/sysctl_net.c
index 5bc1a3d5740130a896e19f47b678f22cb5755853..e0c71bd8f7cfaac04150fbc449062f9452ddb2ce 100644 (file)
--- a/net/sysctl_net.c
+++ b/net/sysctl_net.c
@@ -44,7 +44,7 @@ static int net_ctl_permissions(struct ctl_table_header *head,
        struct net *net = container_of(head->set, struct net, sysctls);
 
        /* Allow network administrator to have same access as root. */
-       if (ns_capable(net->user_ns, CAP_NET_ADMIN)) {
+       if (ns_capable_noaudit(net->user_ns, CAP_NET_ADMIN)) {
                int mode = (table->mode >> 6) & 7;
                return (mode << 6) | (mode << 3) | mode;
        }