From mboxrd@z Thu Jan  1 00:00:00 1970
Reply-To: kernel-hardening@lists.openwall.com
Date: Wed, 14 Sep 2016 14:20:55 -0700
From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Message-ID: <20160914212054.GC57174@ast-mbp.thefacebook.com>
References: <20160914072415.26021-1-mic@digikod.net>
 <20160914072415.26021-22-mic@digikod.net>
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In-Reply-To: <20160914072415.26021-22-mic@digikod.net>
Subject: [kernel-hardening] Re: [RFC v3 21/22] bpf,landlock: Add optional skb pointer in the
 Landlock context
To: =?iso-8859-1?Q?Micka=EBl_Sala=FCn?= <mic@digikod.net>
Cc: linux-kernel@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>, Andy Lutomirski <luto@amacapital.net>, Arnd Bergmann <arnd@arndb.de>, Casey Schaufler <casey@schaufler-ca.com>, Daniel Borkmann <daniel@iogearbox.net>, Daniel Mack <daniel@zonque.org>, David Drysdale <drysdale@google.com>, "David S . Miller" <davem@davemloft.net>, Elena Reshetova <elena.reshetova@intel.com>, "Eric W . Biederman" <ebiederm@xmission.com>, James Morris <james.l.morris@oracle.com>, Kees Cook <keescook@chromium.org>, Paul Moore <pmoore@redhat.com>, Sargun Dhillon <sargun@sargun.me>, "Serge E . Hallyn" <serge@hallyn.com>, Tejun Heo <tj@kernel.org>, Will Drewry <wad@chromium.org>, kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org, linux-security-module@vger.kernel.org, netdev@vger.kernel.org, cgroups@vger.kernel.org
List-ID: <kernel-hardening.lists.openwall.com>

On Wed, Sep 14, 2016 at 09:24:14AM +0200, Mickaël Salaün wrote:
> This is a proof of concept to expose optional values that could depend
> of the process access rights.
> 
> There is two dedicated flags: LANDLOCK_FLAG_ACCESS_SKB_READ and
> LANDLOCK_FLAG_ACCESS_SKB_WRITE. Each of them can be activated to access
> eBPF functions manipulating a skb in a read or write way.
> 
> Signed-off-by: Mickaël Salaün <mic@digikod.net>
...
>  /* Handle check flags */
>  #define LANDLOCK_FLAG_FS_DENTRY		(1 << 0)
> @@ -619,12 +621,15 @@ struct landlock_handle {
>   * @args: LSM hook arguments, see include/linux/lsm_hooks.h for there
>   *        description and the LANDLOCK_HOOK* definitions from
>   *        security/landlock/lsm.c for their types.
> + * @opt_skb: optional skb pointer, accessible with the
> + *           LANDLOCK_FLAG_ACCESS_SKB_* flags for network-related hooks.
>   */
>  struct landlock_data {
>  	__u32 hook; /* enum landlock_hook_id */
>  	__u16 origin; /* LANDLOCK_FLAG_ORIGIN_* */
>  	__u16 cookie; /* seccomp RET_LANDLOCK */
>  	__u64 args[6];
> +	__u64 opt_skb;
>  };

missing something here.
This patch doesn't make use of it.
That's something for the future?
How that field will be populated?
Why make it different vs the rest or args[6] ?