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From: ebiederm@xmission.com (Eric W. Biederman)
To: Christian Brauner <christian.brauner@ubuntu.com>
Cc: davem@davemloft.net,  netdev@vger.kernel.org,
	 linux-kernel@vger.kernel.org,  avagin@virtuozzo.com,
	 ktkhai@virtuozzo.com,  serge@hallyn.com,
	 gregkh@linuxfoundation.org
Subject: Re: [PATCH net-next 2/2 v4] netns: restrict uevents
Date: Sat, 28 Apr 2018 23:23:58 -0500	[thread overview]
Message-ID: <87in8ad4ip.fsf@xmission.com> (raw)
In-Reply-To: <20180428192025.2075-3-christian.brauner@ubuntu.com> (Christian Brauner's message of "Sat, 28 Apr 2018 21:20:25 +0200")


> +	/* fix credentials */
> +	if (owning_user_ns != &init_user_ns) {
> +		struct netlink_skb_parms *parms = &NETLINK_CB(skb);
> +		kuid_t root_uid;
> +		kgid_t root_gid;
> +
> +		/* fix uid */
> +		root_uid = make_kuid(owning_user_ns, 0);
> +		if (!uid_valid(root_uid))
> +			root_uid = GLOBAL_ROOT_UID;
> +		parms->creds.uid = root_uid;
> +
> +		/* fix gid */
> +		root_gid = make_kgid(owning_user_ns, 0);
> +		if (!gid_valid(root_gid))
> +			root_gid = GLOBAL_ROOT_GID;
> +		parms->creds.gid = root_gid;

One last nit:

	You can only make the assignment if the uid is valid.
        Leaving it GLBOAL_ROOT_UID if the composed uid is invalid.
        AKA

		/* fix uid */
		root_uid = make_kuid(owning_user_ns, 0);
		if (uid_valid(root_uid))
                	parms->creds.uid = root_uid;

                /* fix gid */
		root_gid = make_kgid(owning_user_ns, 0);
                if (gid_valid(root_gid))
                	params->creds.gid = root_gid;


One line shorter and I think a little clearer.  I suspect
it even results in better code.

Eric

  reply	other threads:[~2018-04-29  4:23 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-28 19:20 [PATCH net-next 0/2 v4] netns: uevent filtering Christian Brauner
2018-04-28 19:20 ` [PATCH net-next 1/2 v4] uevent: add alloc_uevent_skb() helper Christian Brauner
2018-04-28 19:20 ` [PATCH net-next 2/2 v4] netns: restrict uevents Christian Brauner
2018-04-29  4:23   ` Eric W. Biederman [this message]
2018-04-29  9:59     ` Christian Brauner
2018-04-29  4:25 ` [PATCH net-next 0/2 v4] netns: uevent filtering Eric W. Biederman

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