Message-ID: <511FED8E.7020308@RedHat.com>
Date: Sat, 16 Feb 2013 15:35:26 -0500
From: Steve Dickson <SteveD@redhat.com>
MIME-Version: 1.0
To: "J. Bruce Fields" <bfields@fieldses.org>
CC: Trond Myklebust <Trond.Myklebust@netapp.com>,
        "J. Bruce Fields" <bfields@redhat.com>,
        "David P. Quigley" <dpquigl@tycho.nsa.gov>,
        Linux NFS list <linux-nfs@vger.kernel.org>,
        Linux FS devel list <linux-fsdevel@vger.kernel.org>,
        Linux Security List <linux-security-module@vger.kernel.org>,
        SELinux List <selinux@tycho.nsa.gov>
Subject: Re: [PATCH 10/15] NFS: Client implementation of Labeled-NFS
References: <1360327163-20360-1-git-send-email-SteveD@redhat.com> <1360327163-20360-11-git-send-email-SteveD@redhat.com> <20130212230346.GN10267@fieldses.org>
In-Reply-To: <20130212230346.GN10267@fieldses.org>
Content-Type: text/plain; charset=ISO-8859-1
Sender: linux-nfs-owner@vger.kernel.org

On 12/02/13 18:03, J. Bruce Fields wrote:
>> +static int decode_attr_security_label(struct xdr_stream *xdr, uint32_t *bitmap,
>> > +					struct nfs4_label *label)
>> > +{
>> > +	uint32_t pi = 0;
>> > +	uint32_t lfs = 0;
>> > +	__u32 len;
>> > +	__be32 *p;
>> > +	int status = 0;
>> > +
>> > +	if (unlikely(bitmap[2] & (FATTR4_WORD2_SECURITY_LABEL - 1U)))
>> > +		return -EIO;
>> > +	if (likely(bitmap[2] & FATTR4_WORD2_SECURITY_LABEL)) {
>> > +		p = xdr_inline_decode(xdr, 4);
>> > +		if (unlikely(!p))
>> > +			goto out_overflow;
>> > +		lfs = be32_to_cpup(p++);
>> > +		p = xdr_inline_decode(xdr, 4);
>> > +		if (unlikely(!p))
>> > +			goto out_overflow;
>> > +		pi = be32_to_cpup(p++);
>> > +		p = xdr_inline_decode(xdr, 4);
>> > +		if (unlikely(!p))
>> > +			goto out_overflow;
>> > +		len = be32_to_cpup(p++);
>> > +		p = xdr_inline_decode(xdr, len);
>> > +		if (unlikely(!p))
>> > +			goto out_overflow;
>> > +		if (len < XDR_MAX_NETOBJ) {
>> > +			if (label) {
>> > +				nfs4_label_init(label);
>> > +				if (label->len < len) {
> If I remember the earlier patch right, nfs4_label_init() just set
> label->len to NFS4_MAXLABELLEN.
Good good catch... XDR_MAX_NETOBJ should be NFS4_MAXLABELLEN.

> 
> Doesn't that overwrite the length that was passed into
> nfs4_get_security_label?
Yes... the len will be set to the actual size of the label which
will be less than NFS4_MAXLABELLEN. So I'm thinking this overwrite 
of the is fine.

This is the reason nfs4_label_init() resets len to NFS4_MAXLABELLEN

steved.