linux-kernel - Re: [RFC PATCH 2/5] ima: Add ns_status for storing namespaced iint data

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Message-Id: <9a2ae1ef-95c3-6eb3-bf4d-78b84d5a77e4@linux.vnet.ibm.com>
Date:   Fri, 11 Aug 2017 11:00:52 -0400
From:   Stefan Berger <stefanb@...ux.vnet.ibm.com>
To:     Mehmet Kayaalp <mkayaalp@...ux.vnet.ibm.com>,
        ima-devel <linux-ima-devel@...ts.sourceforge.net>
Cc:     containers <containers@...ts.linux-foundation.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-security-module <linux-security-module@...r.kernel.org>,
        Tycho Andersen <tycho@...ker.com>,
        "Serge E . Hallyn" <serge@...lyn.com>,
        Yuqiong Sun <sunyuqiong1988@...il.com>,
        David Safford <david.safford@...com>,
        Mehmet Kayaalp <mkayaalp@...binghamton.edu>
Subject: Re: [RFC PATCH 2/5] ima: Add ns_status for storing namespaced iint
 data

On 07/20/2017 06:50 PM, Mehmet Kayaalp wrote:
> This patch adds an rbtree to the IMA namespace structure that stores a
> namespaced version of iint->flags in ns_status struct. Similar to the
> integrity_iint_cache, both the iint ns_struct are looked up using the
> inode pointer value. The lookup, allocate, and insertion code is also
> similar, except ns_struct is not free'd when the inode is free'd.
> Instead, the lookup verifies the i_ino and i_generation fields are also a
> match. A lazy clean up of the rbtree that removes free'd inodes could be
> implemented to reclaim the invalid entries.
>
> Signed-off-by: Mehmet Kayaalp <mkayaalp@...ux.vnet.ibm.com>
> ---
>   include/linux/ima.h             |   3 +
>   security/integrity/ima/ima.h    |  16 ++++++
>   security/integrity/ima/ima_ns.c | 120 ++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 139 insertions(+)
>
>
> @@ -181,3 +198,106 @@ struct ima_namespace init_ima_ns = {
>   	.parent = NULL,
>   };
>   EXPORT_SYMBOL(init_ima_ns);
> +
> +/*
> + * __ima_ns_status_find - return the ns_status associated with an inode
> + */
> +static struct ns_status *__ima_ns_status_find(struct ima_namespace *ns,
> +					      struct inode *inode)
> +{
> +	struct ns_status *status;
> +	struct rb_node *n = ns->ns_status_tree.rb_node;
> +
> +	while (n) {
> +		status = rb_entry(n, struct ns_status, rb_node);
> +
> +		if (inode < status->inode)
> +			n = n->rb_left;
> +		else if (inode->i_ino > status->i_ino)
> +			n = n->rb_right;

Above you are comparing with the inode ptr, here with i_ino. Why can you 
not compare with inode both times. Also the insertion only seems to 
consider the inode ptr.

    Stefan