selinux: suppress warning flood for retired DCCP netlink messages

When deploying linux-6.18.y stable kernel to production servers, we
observed kernel dmesg being flooded with SELinux warnings when running
`ss -l`:

  SELinux: unrecognized netlink message: protocol=4 nlmsg_type=19 \
    sclass=netlink_tcpdiag_socket pid=188945 comm=ss

The root cause is that DCCP support was retired in
commit 2a63dd0edf38 ("net: Retire DCCP socket."). Consequently,
DCCPDIAG_GETSOCK was removed from nlmsg_tcpdiag_perms. This causes
nlmsg_perm() to return -EINVAL, triggering the SELinux warning for every
`ss -l` invocation [0].

Use pr_warn_once() for the retired DCCPDIAG_GETSOCK to prevent message
flooding.

Link: https://github.com/iproute2/iproute2/blob/main/misc/ss.c#L3901 [0]
Fixes: 2a63dd0edf38 ("net: Retire DCCP socket.")
Suggested-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Kuniyuki Iwashima <kuniyu@google.com>
Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

0 files changed, 0 insertions, 0 deletions