linux-kernel - Re: [PATCH 2/2] net: Use ns_capable_noaudit() when determining net sysctl permissions

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Message-ID: <20160509042420.GB22508@ubuntumail>
Date:	Mon, 9 May 2016 04:24:20 +0000
From:	Serge Hallyn <serge.hallyn@...ntu.com>
To:	Tyler Hicks <tyhicks@...onical.com>
Cc:	linux-security-module@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Serge Hallyn <serge.hallyn@...onical.com>,
	"David S . Miller" <davem@...emloft.net>
Subject: Re: [PATCH 2/2] net: Use ns_capable_noaudit() when determining net
 sysctl permissions

Quoting Tyler Hicks (tyhicks@...onical.com):
> The capability check should not be audited since it is only being used
> to determine the inode permissions. A failed check does not indicate a
> violation of security policy but, when an LSM is enabled, a denial audit
> message was being generated.
> 
> The denial audit message caused confusion for some application authors
> because root-running Go applications always triggered the denial. To
> prevent this confusion, the capability check in net_ctl_permissions() is
> switched to the noaudit variant.
> 
> BugLink: https://launchpad.net/bugs/1465724
> 
> Signed-off-by: Tyler Hicks <tyhicks@...onical.com>

Acked-by: Serge E. Hallyn <serge.hallyn@...ntu.com>

> ---
>  net/sysctl_net.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/sysctl_net.c b/net/sysctl_net.c
> index ed98c1f..46a71c7 100644
> --- a/net/sysctl_net.c
> +++ b/net/sysctl_net.c
> @@ -46,7 +46,7 @@ static int net_ctl_permissions(struct ctl_table_header *head,
>  	kgid_t root_gid = make_kgid(net->user_ns, 0);
>  
>  	/* Allow network administrator to have same access as root. */
> -	if (ns_capable(net->user_ns, CAP_NET_ADMIN) ||
> +	if (ns_capable_noaudit(net->user_ns, CAP_NET_ADMIN) ||
>  	    uid_eq(root_uid, current_euid())) {
>  		int mode = (table->mode >> 6) & 7;
>  		return (mode << 6) | (mode << 3) | mode;
> -- 
> 2.7.4
>