linux-kernel - Re: [RFC 4/7] selinux: mark __ro_mostly_after_init for selinux_hooks/selinux_nf

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Date:   Tue, 21 Feb 2017 19:35:21 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     Hoeun Ryu <hoeun.ryu@...il.com>,
        kernel-hardening@...ts.openwall.com, linux-kernel@...r.kernel.org
Cc:     Paul Moore <paul@...l-moore.com>,
        Stephen Smalley <sds@...ho.nsa.gov>,
        Eric Paris <eparis@...isplace.org>,
        James Morris <james.l.morris@...cle.com>,
        "Serge E. Hallyn" <serge@...lyn.com>, selinux@...ho.nsa.gov,
        linux-security-module@...r.kernel.org
Subject: Re: [RFC 4/7] selinux: mark __ro_mostly_after_init for
 selinux_hooks/selinux_nf_ops

On 2017/02/19 19:04, Hoeun Ryu wrote:
>  It would be good that selinux hooks objects are marked as
> `__ro_mostly_after_init`. They can not be simply marked as `__ro_after_init'
> because they should be writable during selinux_disable procedure.
> `__ro_mostly_after_init` section is temporarily read-write during
> selinux_disable procedure via set_ro_mostly_after_init_rw/ro pair. Now that
> they can be read-only except during the procedure.
> 
> -static struct security_hook_list selinux_hooks[] = {
> +static struct security_hook_list selinux_hooks[] __ro_mostly_after_init = {

This won't work. This variable is array of "struct list_head".
You need to set same attribute to variables pointed by
"struct list_head"->next and "struct list_head"->prev .

>  	LSM_HOOK_INIT(binder_set_context_mgr, selinux_binder_set_context_mgr),
>  	LSM_HOOK_INIT(binder_transaction, selinux_binder_transaction),
>  	LSM_HOOK_INIT(binder_transfer_binder, selinux_binder_transfer_binder),